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WO2013039189A1 - Plasma generation device and emission spectrophotometer - Google Patents

Plasma generation device and emission spectrophotometer Download PDF

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Publication number
WO2013039189A1
WO2013039189A1 PCT/JP2012/073585 JP2012073585W WO2013039189A1 WO 2013039189 A1 WO2013039189 A1 WO 2013039189A1 JP 2012073585 W JP2012073585 W JP 2012073585W WO 2013039189 A1 WO2013039189 A1 WO 2013039189A1
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WIPO (PCT)
Prior art keywords
narrow portion
channel
plasma
sectional area
cross
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PCT/JP2012/073585
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French (fr)
Japanese (ja)
Inventor
高村　禅
山本　保
Original Assignee
国立大学法人北陸先端科学技術大学院大学
株式会社マイクロエミッション
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Application filed by 国立大学法人北陸先端科学技術大学院大学, 株式会社マイクロエミッション filed Critical 国立大学法人北陸先端科学技術大学院大学
Priority to JP2013533727A priority Critical patent/JP6083047B2/en
Publication of WO2013039189A1 publication Critical patent/WO2013039189A1/en

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/48—Generating plasma using an arc
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/66—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light electrically excited, e.g. electroluminescence
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/71—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited
    • G01N21/73—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited using plasma burners or torches
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/0006—Investigating plasma, e.g. measuring the degree of ionisation or the electron temperature
    • H05H1/0012—Investigating plasma, e.g. measuring the degree of ionisation or the electron temperature using electromagnetic or particle radiation, e.g. interferometry
    • H05H1/0025—Investigating plasma, e.g. measuring the degree of ionisation or the electron temperature using electromagnetic or particle radiation, e.g. interferometry by using photoelectric means
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/0006—Investigating plasma, e.g. measuring the degree of ionisation or the electron temperature
    • H05H1/0012—Investigating plasma, e.g. measuring the degree of ionisation or the electron temperature using electromagnetic or particle radiation, e.g. interferometry
    • H05H1/0037—Investigating plasma, e.g. measuring the degree of ionisation or the electron temperature using electromagnetic or particle radiation, e.g. interferometry by spectrometry

Definitions

  • the present invention relates to a plasma generator and an emission spectroscopic analyzer. More specifically, the present invention relates to a plasma generation apparatus and an emission spectroscopic analysis apparatus for identifying and quantifying an element based on an emission spectrum from an element contained in a solution.
  • microfluids have been developed to apply semiconductor processes to create small flow channels, reaction vessels, analytical instruments, etc. on a wafer and complete a series of chemical experiments necessary for blood testing on a single chip.
  • Research fields called “ ⁇ TAS” and “Lab on a chip” are rapidly developing.
  • a method has been developed in which minute plasma is generated and a mist-like solution is introduced therein to perform elemental analysis.
  • Non-Patent Document 1 As another method of generating plasma, a method of generating plasma by inserting an electrode into a solution and passing a current directly through the solution has been reported (for example, see Non-Patent Document 1).
  • the advantage of this method is that plasma is generated in the solution, and the evaporation of the solution plays the role of gasification of the specimen, so that a nebulizer is not required.
  • the impurities contained in the solid electrode evaporate, and it is difficult to avoid contamination of the impurities.
  • a narrow portion having a cross-sectional area significantly smaller than the cross-sectional area of the flow channel is provided in the flow channel formed of an insulating material, and the flow channel and the narrow portion are electrically conductive.
  • a liquid electrode plasma (LEP: Liquid Electrode Plasma) type emission spectroscopic analyzer (hereinafter referred to as LEP: Liquid Electrode Plasma) type that applies an electric field to the narrow part so that the electric field passes through the narrow part and generates plasma in the narrow part.
  • LEP Liquid Electrode Plasma
  • a simple LEP emission analyzer, LEP device, or LEP has already been proposed (for example, Patent Document 2).
  • This LEP has an advantage that plasma can be easily generated while reducing the amount of impurities when performing an emission analysis of elements contained in a conductive liquid. In addition, this LEP achieves downsizing of the apparatus, dramatic reduction in consumption gas and power consumption, and reduction in apparatus cost while having performance equivalent to that of ICP emission analysis.
  • the conventional LEP already proposed generates plasma in a narrow portion disposed between the electrodes when a high voltage is applied between the electrodes, but lead (Pb), thallium (Tl), cadmium (cd) In some elements such as), a sufficient amount of light cannot be obtained, and there remains a problem that measurement sensitivity is low. In other words, there are elements that cannot be measured quantitatively with the proposed technique.
  • JP 2002-257785 A Japanese Patent No. 3932368
  • the present invention has been proposed in view of such conventional circumstances, and an object thereof is to provide a plasma generation apparatus and an emission spectroscopic analysis apparatus that eliminate the disadvantages of the conventional techniques. That is, an object of the present invention is to provide a plasma generation apparatus having a long plasma generation time and an emission spectroscopic analysis apparatus having a very high measurement sensitivity.
  • Another object of the present invention is to provide an emission spectroscopic analyzer capable of detecting and analyzing even a trace amount of elements by expanding the elements that can be detected as compared with conventional LEP emission analyzers.
  • the present inventors have found that for some elements, the sensitivity is particularly poor when the voltage is forcibly cut off in a short time and the plasma generation time is shortened. Furthermore, the present inventors have found out a cause of this sensitivity decrease and also found out a method for eliminating the sensitivity decrease. These are described in detail below.
  • positive pressure release is also effective in suppressing movement of a specific interface, and for this purpose, an interface that has little contribution to light emission and plasma maintenance (that is, the above-mentioned specific specification). We thought that it is effective to actively move a different interface).
  • the inventors of the present invention connected the third and fourth flow paths to a narrow portion to reduce the movement resistance in order to release the pressure positively, and simultaneously reduce the voltage. It has also been conceived that the plasma generation time in the narrow portion can be extended by increasing the movement resistance of the flow path having the role of applying, and the present invention has been completed.
  • the present inventors are also effective to make a difference appear in the fluid movement resistance in the enlarged flow channel formed at both ends of the narrowest narrow channel with the narrowest channel cross-sectional area in the narrow portion, for example, If the enlarged flow path at both ends of the narrowest flow path is formed from a conventional symmetrical structure to an asymmetrical structure, the moving speed of the interface to one electrode side can be made slower than that to the other electrode side. It has been found that the time and region where concentration occurs can be increased, and the present invention has been completed.
  • a plasma generator for generating plasma in a conductive liquid A transport channel for transporting the conductive liquid and formed of an insulating material; A narrow portion connected to the transport channel and having a cross-sectional area significantly smaller than the cross-sectional area of the transport channel; Means for applying an electric field to the narrow portion so that the electric field passes through the narrow portion; And having The plasma generating apparatus according to claim 1, wherein a movement resistance of the conductive liquid is larger in a part of the narrow part than in another part.
  • the narrow portion is formed with a throat portion having the smallest channel cross-sectional area, and enlarged channels connected to the transport channel on both sides of the throat portion, 2.
  • the plasma generating apparatus according to aspect 1, wherein the enlarged flow channel on one side has a larger movement resistance of the conductive liquid than the enlarged flow channel on the other side.
  • the plasma generating apparatus according to aspect 2 wherein the enlarged flow path is configured asymmetrically with respect to the throat.
  • the throat is disposed closer to the other end than one end of the narrow portion;
  • the enlarged channel has a channel cross-sectional area that gradually expands from the throat toward the transport channel, The maximum channel cross-sectional area of the expanded channel disposed on the one end side is larger than the maximum channel cross-sectional area of the expanded channel disposed on the other end side, 4.
  • the maximum flow path cross-sectional area of the enlarged flow path disposed on the one end side is 1.1 to 100 times the flow path cross-sectional area at the throat portion, and the flow path cross-sectional area disposed on the other end side is 5.
  • the plasma generating apparatus according to aspect 4 wherein the maximum flow path cross-sectional area of the enlarged flow path is 1.1 to 50 times the cross-sectional area of the throat. (Aspect 6) 6.
  • the plasma generating apparatus further comprising a pressure adjusting mechanism that locally increases or decreases the pressure of the conductive liquid in the narrow portion.
  • a plasma generator for generating plasma in a conductive liquid A transport channel for transporting the conductive liquid and formed of an insulating material; A narrow portion connected to the transport channel and having a cross-sectional area significantly smaller than the cross-sectional area of the transport channel; Means for applying an electric field to the narrow portion so that the electric field passes through the narrow portion; And having An outlet channel is further disposed in the narrow portion, Guiding the conductive liquid so as to flow into the narrow portion from the transport channel and out of the outlet channel via the narrow portion; A pressure adjusting mechanism for increasing or decreasing the pressure of the conductive liquid locally is provided in the outlet channel, or a sectional area of the outlet channel is made larger than the sectional area of the narrow portion.
  • the means for applying an electric field to the narrow portion includes a solution reservoir in which an electrode is inserted, and a supply pipe for supplying the conductive liquid to the solution reservoir, and The length of the supply pipe is not less than 10 times the length of the transport flow path, or the cross-sectional area of the supply pipe is 1/10 or less of the cross-sectional area of the transport flow path.
  • the plasma generator according to any one of aspects 1 to 7. (Aspect 9) 9. The plasma generator according to any one of aspects 1 to 8, wherein an alternating voltage is used to apply an electric field to the narrow portion.
  • a plasma generator for generating plasma in a conductive liquid A transport channel for transporting the conductive liquid and formed of an insulating material; A narrow portion disposed in the transport channel and having a cross-sectional area significantly smaller than the cross-sectional area of the transport channel; Means for applying an electric field to the narrow portion so that the electric field passes through the narrow portion; And having The means includes a negative electrode and a positive electrode, The narrow portion is formed with a throat portion having the smallest channel cross-sectional area and an enlarged channel that is connected to one opening of the throat portion and has different channel lengths.
  • the expanded channel having a large channel length is configured to be arranged on either the minus electrode or the plus electrode depending on the type of element that generates the plasma. Generator.
  • a plasma generator for generating plasma in a conductive liquid A transport channel for transporting the conductive liquid and formed of an insulating material; A narrow portion connected to the transport channel and having a cross-sectional area significantly smaller than the cross-sectional area of the transport channel; An electrode for applying an electric field to the narrow portion so that the electric field passes through the narrow portion; And having An outlet channel is further disposed in the narrow portion, Guiding the conductive liquid so as to flow into the narrow portion from the transport channel and out of the outlet channel via the narrow portion; The plasma generator according to claim 1, wherein the electric field is applied so that a supply speed of the liquid to the narrow portion and an evaporation speed of the liquid in the narrow portion are balanced.
  • An emission spectroscopic analysis apparatus comprising the plasma generator according to any one of embodiments 1 to 11.
  • the narrow portion refers to a channel provided in the transport channel and having a significantly smaller channel cross-sectional area than the transport channel.
  • the narrow portion preferably includes a throat portion having the smallest channel cross-sectional area, and an enlarged channel provided on both sides of the throat portion and connecting the throat portion and the transport channel.
  • the cross-sectional area of the enlarged channel is more preferably a divergent channel that gradually expands from the throat toward the transport channel.
  • the enlarged flow path has an asymmetric flow path structure with the throat as a starting point.
  • the end cross-sectional area of one enlarged flow path is about 1.1 to 100 times, and the end cross-sectional area of the other enlarged flow path is about 1.1 to 50 times. It is preferable to constitute an asymmetric narrow portion such as
  • the insulating material examples include olefinic resins such as glass, polyethylene, and polypropylene, silicones such as polydimethylsiloxane, fluororesins, and ceramics, but the present invention is not limited to such examples.
  • the flow path (transport flow path or flow path in the narrow portion) can be formed on a plate-shaped chip or plate made of an insulating material using a lithography technique, for example.
  • the narrow portion for example, a molded body having a shape that can be detachably disposed in the transport channel (can be manufactured by an injection molding method capable of mass production) may be prepared. It can be replaced with a new narrow part as appropriate and used as a cartridge.
  • the liquid sample to be analyzed is used as the conductive liquid that fills the channel and the narrow part.
  • the electrolyte used for the conductive liquid include nitric acid, acetic acid, hydrochloric acid, and the like. Among these, nitric acid having characteristics that do not easily cause an obstacle to analysis is preferable.
  • As the sample various materials can be measured, but an electrolyte made of an element such as nitric acid that does not interfere with analysis is preferable.
  • an electric field is applied to the narrow portion by a method such as applying an electric field along the narrow portion so that the electric field passes through the narrow portion.
  • a method such as applying an electric field along the narrow portion so that the electric field passes through the narrow portion.
  • the emission intensity is about 4 to 10 times that of the conventional apparatus proposed in Patent Document 2, so that elemental analysis with extremely high sensitivity is possible. It becomes.
  • an elemental analysis was performed using an asymmetric flow path of a predetermined size as a narrow portion and a 0.1 M nitric acid aqueous solution mixed with 100 ppm of lead (Pb) as a conductive liquid, the same conditions were obtained at an emission wavelength of 406 nm.
  • the emission intensity was about 10 times that of the conventional device (about 800 (arbitrary unit) for the conventional device and about 8000 (arbitrary unit) for the device of the present invention).
  • Example 1 It is a figure explaining the principal part of the plasma generator of this invention.
  • Example 1 It is a figure explaining the suitable structure of a narrow part.
  • Example 1 It is a figure explaining the structure of the emission-spectral-analysis apparatus of this invention.
  • FIG. 4 is a graph showing light emission intensity measured using the apparatus of Example 2.
  • FIG. 4 is a graph showing light emission intensity measured using the apparatus of Example 2.
  • FIG. 4 is a graph showing light emission intensity measured using the apparatus of Example 2.
  • FIG. 4 is a graph showing light emission intensity measured using the apparatus of Example 2. It is the figure which showed the relationship between an element and emitted light intensity. It is the figure which showed the introduction process of the element to the plasma in a conventional apparatus (ICP apparatus).
  • ICP apparatus ICP apparatus
  • FIG. It is the figure which showed the emitted light intensity measured using the apparatus of Example 6.
  • FIG. It is the simulation result which showed the relationship between the integration pulse number and the interface concentration rate, and the relationship between the integration pulse number and the element introduction rate to the plasma. It is a figure explaining movement resistance of a certain liquid in a certain channel.
  • Example 1 An example (Example 1) of the plasma generator of the present invention is shown in FIG.
  • the plasma generator 1 of Example 1 includes two solution reservoirs 102 as shown in FIG.
  • Each solution reservoir 102, 102 is provided with an opening, and an electrode 104 (specifically, 104a, 104b) is inserted into the solution reservoir 102, 102 from this opening.
  • the two solution reservoirs 102, 102 are connected to each other via transport channels 101, 101 separated by a narrow portion 103.
  • the narrow portion 103 is preferably detachably disposed on the plasma generator 1.
  • the wall surfaces of the transport channels 101 and 101, the narrow portion 103, and the solution reservoirs 102 and 102 are formed of an insulating material.
  • the conveyance channels 101 and 101 and the narrow portion 103 confine the conductive liquid 105 when the two solution reservoirs 102 and 102 are filled with the conductive liquid 105 (hereinafter, also simply referred to as liquid or solution), and the electrode 104a. , 104b, an electric field is generated in the vicinity of the narrow portion 103 by applying a voltage.
  • the narrow portion 103 connected to the transport channels 101, 101 on both sides has a channel cross-sectional area smaller than the channel cross-sectional area of other parts (the transport channels 101, 101 and the solution reservoirs 102, 102). Therefore, in this narrow portion 103 (particularly the throat portion 108), current and electric field are concentrated, the temperature becomes higher than the other portions 101 and 102, and boiling and plasma 106 are likely to occur.
  • the conductive liquid 105 needs to contain an element to be measured and have conductivity.
  • an electrolyte supporting salt
  • electrolytes nitric acid is suitable because its constituent elements are contained in the air and in water, and it has a property of dissolving metals well.
  • the liquid temperature of the conductive liquid 105 is not particularly limited, but is usually 15 to 40 ° C., preferably about 20 to 25 ° C.
  • the material used for the electrode 104 is preferably a noble metal such as platinum or carbon that is unlikely to be corroded by passing an electric current.
  • a voltage between the pair of electrodes 104a and 104b current and electric field are concentrated in the narrow portion 103, so that bubbles are generated, and plasma 106 is generated in the generated bubbles.
  • elemental analysis of the conductive liquid 105 can be easily performed.
  • the throat portion 108 is formed in the narrow portion 103, but the throat portion 108 is disposed closer to the other end 109b than the one end 109a of the narrow portion 103, and the throat portion On both sides 108, asymmetric enlarged flow passages 107a and 107b having different flow passage volumes and flow passage sectional areas (and enlargement ratios) are formed.
  • the mass of the conductive liquid 105 confined in one enlarged flow path 107a is larger than the mass of the conductive liquid 105 confined in the other enlarged flow path 107b.
  • the evaporation (and thus the plasma 106) region generated from the throat 108 propagates and propagates in both directions.
  • the conductivity is increased.
  • the movement resistance of the liquid 105 is increased. Therefore, the plasma generation time of the conductive liquid 105 in the enlarged flow path 107a is longer than that in the other enlarged flow paths 107b.
  • the interface concentration effect in the one enlarged flow path 107a is enhanced, and the amount of vaporization of the analysis target element existing there is also increased, so that the measurement sensitivity of the element can be improved.
  • FIG. 2 illustrates a preferred configuration within the narrow portion 103.
  • 2A is a cross-sectional view of the narrow portion 103 fractured in the horizontal direction (perpendicular to the paper surface in FIG. 1)
  • FIG. 2B is the vertical direction (the direction parallel to the paper surface in FIG. 1). It is sectional drawing of the narrow part 103 fractured
  • the narrow portion 103 has a length L of 1800 ⁇ m and a constant width W of 220 ⁇ m in the horizontal direction.
  • the vertical width that is, the channel height
  • the vertical width changes in the length direction, and is 400 ⁇ m (channel height H a ) at one end 109a and 100 ⁇ m (channel height H b ) at the other end 109b.
  • the position of the throat 108 is not the center of the narrow portion 103 (900 ⁇ m from either end) as in the prior art, but is a position biased toward either end (in the example of FIG. 2, from one end 109 a to 1500 ⁇ m). Note that (distance L a ), 300 ⁇ m (distance L b ) away from the other end 109b).
  • the channel cross-sectional area at the end 109b is set to about 1.1 to 50 times the channel cross-sectional area at the throat 108, and the channel cross-sectional area at the end 109a is set to about 1.1 to 50 times. It is preferable to set to about 1.1 times to 100 times.
  • FIG. 3 shows an example (Example 2) of an emission spectroscopic analyzer 2 in which the plasma generator 1 of the present invention is used.
  • the apparatus 2 shown in FIG. 3 is an emission spectroscopic analysis apparatus that detects plasma emission using a photosensor and controls power supply.
  • a sheet-like chip 202 made of an insulating material such as polydimethylsiloxane (hereinafter referred to as PDMS) and patterned with a narrow portion 103 is placed on the quartz glass 201.
  • the chip 202 is manufactured by taking a flow path pattern of a resist material by photolithography. By placing the chip 202 on the quartz glass 201, the chip 202 naturally adheres to form a microchannel.
  • a solution reservoir 102 is formed by opening a hole in a portion corresponding to the end of the transport channel 101 by using a narrow hole device such as a punch.
  • Examples of the conductive liquid 105 include a liquid obtained by diluting a physiological condition phosphate buffer to 1/20 (volume ratio).
  • Examples of the electrodes 104 and 104 include platinum wires having a diameter of 0.5 mm. In order to pass an electric field through the narrow portion 103 and apply an electric field to the narrow portion 103, electrodes 104 and 104 connected to the power source 301 are inserted into the solution reservoirs 102 and 102. The wire-like electrodes 104 and 104 are generally inserted into the solution reservoirs 102 and 102 through a pipe (not shown) that supplies the conductive liquid 105.
  • a plasma 106 is generated in the narrow portion 103.
  • the light from the plasma 106 is introduced into the optical fiber 204, the spectrum is measured with a spectroscope 304 (for example, USB2000 manufactured by Ocean Optics), and the measured data is collected and analyzed by a computer 305 to perform emission spectroscopic analysis. It can be carried out.
  • a spectroscope 304 for example, USB2000 manufactured by Ocean Optics
  • the light generated by the plasma 106 is captured by a photosensor (not shown) built in the photosensor unit 302 disposed below the chip 202.
  • the photo sensor unit 302 controls the connection and disconnection of the electric field by the switch 303 based on the light emission intensity captured by the photo sensor, and stops the application of the electric field after a specified time from the generation of the plasma 106, whereby the light emission intensity, The light emission time and the number of times of light emission can be controlled.
  • the emission intensity of the metal element contained in the conductive liquid 105 was measured using the emission spectroscopic analyzer 2 having the above-described configuration (hereinafter referred to as a first evaluation test).
  • a first evaluation test As a measurement object, the narrow portion 103 of the present invention having the asymmetric enlarged flow passages 107a and 107b with the throat portion 108 as a base point, and the conventional narrow portion with a symmetrical flow passage with the throat portion 108 as a base point (comparative example).
  • Quartz was used as the material of the chip 202 surrounding the narrow portion 103 and the solution reservoir 102.
  • a platinum wire having a diameter of 0.5 mm was used as the plus side electrode 104b and the minus side electrode 104a, and a voltage of about 700 V to 950 V was intermittently applied between these electrodes 104a and 104b (specifically, voltage on (Pulse application was repeated 10 times with a period of 3 ms (milliseconds) and a voltage off time of 2 ms).
  • the narrow portion 103 constitutes an asymmetric channel.
  • the conductive liquid 105 includes a transition metal element to be measured (lead 100 mg / L (that is, 100 ppm Pb) or thallium 10 mg / L (that is, 10 ppm Tl)) or an alkali metal element (potassium 100 mg / L (that is, 100 ppm K) or sodium 5 mg / L (ie 5 ppm Na)).
  • a transition metal element to be measured lead 100 mg / L (that is, 100 ppm Pb) or thallium 10 mg / L (that is, 10 ppm Tl)
  • an alkali metal element potassium 100 mg / L (that is, 100 ppm K) or sodium 5 mg / L (ie 5 ppm Na)
  • An aqueous solution of 0.1 M nitric acid (HNO 3 ) was used as the solvent.
  • FIG. 4 shows the change in the emission intensity (arbitrary unit) of lead (Pb, 406 nm) corresponding to the value of the applied voltage.
  • FIG. 4A shows a change in light emission amount (which is an arbitrary unit and is also referred to as light emission intensity in the specification) when the comparative example in which the enlarged flow paths 107 and 107 in the narrow portion 103 are symmetrical is used.
  • 4B and 4C show the amount of light emitted when the present Example 2 in which the enlarged flow paths 107 and 107 in the narrow portion 103 are asymmetric is used.
  • Example 4C shows that the end 109b having a smaller flow path height Hb is directed to the positive electrode side 104b, and the end 109a having a larger flow path height H a is a negative electrode. It is a measurement result of the structure (henceforth "Example 1C") which installed the narrow part 103 so that it may face 104a side.
  • FIGS. 5, 6, and 7 in FIGS. 5, 6, and 7 to be described later, only the kind of the provided conductive liquid 105 is different, and the flow path configuration and arrangement of the narrow portion 103 are shown in FIG. (A), (B), and (C) are the same, and the flow path configuration and arrangement conditions of the narrow portion 103 shown in (A), (B), and (C) of each figure correspond to each other. Yes. Therefore, the re-explanation about these is omitted.
  • Each graph of FIG. 5 shows the change in the emission intensity of thallium (Tl, 535 nm) according to the value of the applied voltage.
  • the emission intensity increases as the voltage increases.
  • the increase rate of the emission intensity is slightly lower even when the applied voltage is increased compared to the case of Comparative Example 1 in FIG.
  • the rate of increase in emission intensity is significantly higher than that in FIG.
  • the same tendency as that shown in the case of Example 1C and Example 1B in FIG. 4 appears. I understand that.
  • the reason for obtaining the above result is that the conductive liquid 105 mixed with the transition metal element easily evaporates on the negative electrode 104a side, and the narrow portion 103 used in FIGS. distance L a and channel height H a from part 108 to the flow path end 109a of the negative electrode 104a side may be mentioned that is longer. That is, in the configuration of the narrow portion 103 used in FIGS. 4C and 5C, the local movement resistance of the conductive liquid 105 is increased, so that the generation of the plasma 106 is likely to continue for a long time. It is considered that the interface concentration effect on the above side is enhanced, and as a result, the measurement sensitivity of the element existing in the vicinity of the side is increased.
  • FIG. 6 shows changes in the emission intensity of potassium (K, 766 nm) according to the value of the applied voltage.
  • FIG. 7 shows a change in the emission intensity of sodium (Na, 589 nm) according to the value of the applied voltage.
  • the light emission intensity increases as the applied voltage increases in any flow path configuration.
  • the increase in emission intensity of Example 1B and Example 1C is higher than that of the corresponding Comparative Example 1 in any case.
  • Example 1B in FIGS. 6 and 7 a very high emission intensity was obtained, but the variation in the measurement results was also large.
  • the element to be measured shown in FIG. 6 and FIG. 7 is an element that easily emits light, as will be described later, and does not significantly reflect only the influence of the asymmetric channel structure on light emission. It is done.
  • the asymmetric structure in the narrow portion 103 of this embodiment can be said to be a means for producing a difference in the interface concentration effect in the enlarged flow passages 107a and 107b on both sides of the throat portion.
  • the element belonging to the first group is an element that emits light as much as the conventional ICP device even when the conventional LEP device is used.
  • sodium (Na), potassium (K), lithium (Li), silver ( Ag) and the like.
  • An element belonging to the second group is an element whose emission intensity becomes extremely lower than that when using a conventional ICP device when the element is caused to emit light using a conventional LEP device.
  • Heavy metals such as Pb), Tl (thallium), and cadmium (Cd).
  • the element belonging to the third group is an element that has not been atomized, and is an element that hardly emits light even when a voltage is applied for a long time with a conventional LEP device.
  • Al aluminum
  • Zr zirconium
  • FIG. 8 shows the change over time in the emission intensity when a constant voltage (700 V) is applied to each element representing each group using a conventional LEP device.
  • An example of the first group was 2 ppm sodium (Na)
  • an example of the second group was 40 ppm lead (Pb)
  • an example of the third group was 100 ppm zirconium (Zr).
  • sodium (Na) shines even if the application time is short.
  • lead (Pb) shines if the application time is lengthened.
  • Zirconium (Zr) hardly emits light regardless of the application time.
  • the conventional LEP device differs from the conventional ICP device in that the difference in sensitivity as described above appears depending on the element to be applied. In the ICP device and the LEP device, the process of entering the plasma is decisively different. The present inventors have considered.
  • the solution 11 containing the measurement element (symbol M in FIG. 9) is sprayed to the upstream side of the tube 14a by the sprayer 13 together with the carrier gas 12 such as argon. .
  • the carrier gas 12 such as argon.
  • Moisture 15 is also introduced into the tubes 14b, 14c from the other inlets 16,17.
  • the tubes 14a, 14b, and 14c are nested, and the flows in the tubes merge on the downstream side of the tubes 14a, 14b, and 14c.
  • the measurement element M and the moisture 15 are heated on the downstream side of the tube 14c by the coil 18 wound around the outer periphery of the tube 14c, and then the measurement element M is introduced into the plasma 106 (that is, vaporized). Become. That is, as shown in FIG. 9B, the measurement element M is included in the water droplet W, but since the surrounding water droplets W gradually evaporate, any measurement element M is finally introduced into the plasma 106 without fail. Will be.
  • the plasma 106 is changed to an arrow in FIG.
  • the plasma 106 collides with the interface of the solution 105 (hereinafter also referred to as the sputtering action of the plasma 106).
  • the measurement element M enters the plasma 106 (that is, vaporizes) and emits light. That is, the element M belonging to the second group that is difficult to enter the plasma 106 tends to remain in the solution 105. Therefore, the present inventors considered that it is effective to use the interface concentration effect to cause the element M belonging to the second group to emit light in the same manner as the element M belonging to the first group.
  • FIG. 10B shows a simplified model of the plasma 106 generated in the narrow portion 103 and a part of the solution 105 in contact therewith.
  • this model assumes a simple model in which the solution 105 has no flow (that is, the flow rate is zero).
  • the concentration of the element M in the solution 105 is denoted as C o.
  • the element concentration in the portion of the solution 105 in the vicinity of the interface that defines the boundary between the plasma 106 and the solution 105 is denoted as Cb.
  • a symbol V and an arrow in FIG. 10B indicate the moving speed and moving direction of the interface due to evaporation of the solvent.
  • balance balance of concentration of the element M in this area A BD can be expressed by the following equation.
  • K in the equation is a plasma introduction coefficient representing the ease of introduction of the element M into the plasma 106.
  • Time variation of the concentration C b of the element M in the vicinity of the interface, the concentration C from o the moving speed of the area A BD of (VC o), introduction rate of the element M is introduced from the interface into the plasma 106 per unit time (C
  • C This equation means that b K) is subtracted.
  • Figure 11 shows the time course of the introduction rate of C b K of aging and elemental concentration C b in the vicinity of the interface.
  • the left vertical axis represents the concentration C b in the vicinity of the interface
  • the right vertical axis indicates the element introduction rate C b K.
  • the concentration C b of the interface that is, the region A BD near the interface
  • the introduction rate C b K of the element M into the plasma 106 is also constant regardless of the plasma introduction coefficient K if the interface concentration sufficiently progresses with time as shown in the lower curve in FIG. It can be seen that the value gradually approaches the value of (ie, VC o shown on the right axis).
  • asymmetric channel structure for the narrow portion 103 as described above. More preferably, a structure in which the enlarged flow path 107a on the negative electrode side 104a is longer than the enlarged flow path 107b on the positive electrode side 104b is adopted.
  • the reason for adopting such a flow channel structure is that when a voltage is applied, bubbles and plasma 106 are generated in the narrowest throat 108. Our experience has shown that the sputtering action of the plasma 106 described above occurs on the negative electrode side 104a.
  • the introduction of the element M into the plasma 106 is mainly due to the sputtering action, it is considered that the element M is introduced into the plasma 106 from the negative electrode side 104a. If this idea is correct, it is possible to cause interfacial concentration at a longer distance and for a longer time by making the enlarged flow path 107a on the negative electrode side 104a longer.
  • the narrow portion 103 for evaluation As the narrow portion 103 for evaluation, the symmetrical channel A, the asymmetric channel B in which the channel on the positive electrode 104b side is longer than the channel on the negative electrode 104a side, and the channel on the negative electrode 104a side are longer than the channel on the positive electrode 104b side.
  • the asymmetric flow path C was prepared. And the narrow part 103 was mounted in the plasma generator 1, the density
  • the symmetric flow path A, the asymmetric flow path B, and the asymmetric flow path C are the same as the flow path structures described in Comparative Example 1, Example 1B, and Example 1C used in the first evaluation test, respectively.
  • lead (Pb) was used as the measurement element, and an aqueous solution of 0.1 M nitric acid (HNO 3 ) was used as the solvent.
  • a lead (Pb) standard solution is diluted with the above-mentioned solvent, and sample solutions of predetermined concentrations (0 mg / L, 10 mg / L, 20 mg / L, 40 mg / L, 60 mg / L, 80 mg / L, 100 mg / L) 105 was adjusted. Note that 40 L of sample solution 105 was injected into each of the solution reservoirs 102 and 102.
  • An applied voltage intermittently applied between the electrodes 104a and 104b was set to 900 V, and a pulsed voltage composed of a voltage on time of 5 ms and a voltage off time of 60 ms was repeatedly applied 40 times.
  • the strong emission peak wavelength of lead (Pb) was 405.782 nm.
  • the asymmetric flow path A may be better when the measurement object is selected as another element (for example, an element belonging to the first group). This is because in the configuration in which the longer enlarged flow path 107a is arranged on the positive electrode 104b side, interface concentration and thus light emission characteristics may be promoted in the flow path 107a.
  • the asymmetric structure based on the throat 108 is used as a means for producing a difference in the interface concentration effect on both sides of the throat 108 in the narrow portion 103, but the present invention is not limited to this.
  • the following examples are also conceivable.
  • FIG. 13 shows a schematic view of another example (Example 3) of the plasma generator 1.
  • the pressure adjusting mechanism 110 is further provided, and the throat portion 108 in the narrow portion 103 is formed at the center of the flow path length L.
  • the basic features and structure are the same as those of the plasma generator 1 shown in FIG. 1 except that the enlarged flow path 107 (that is, 107a and 107b) connected to the throat 108 is formed symmetrically with respect to the base point. It is the same.
  • the pressure adjustment mechanism 110 includes at least an adjustment pipe 111 and an adjustment container 112 connected to one of the enlarged flow paths 107 a and 107 b (for example, 107 b).
  • the adjustment container 112 is preferably made of a material having flexibility and elasticity that easily deforms when the conductive liquid 105 flows into the inside and returns to the state before deformation when the conductive liquid 105 flows out.
  • the pressure inside or near the adjustment container 112 can be set to a pressure P 1 lower than the pressure P 0 of the conductive liquid 105 at the throat 108.
  • a compressible gas air
  • the gas is compressed by the high-pressure conductive liquid 105 when the plasma 106 is generated, and the pressure in or near the adjustment vessel 112 is set to a pressure P 1 lower than the pressure P 0 at the plasma 106 generation position.
  • Bubbles generated in the throat 108 in the narrow portion 103 due to voltage application are conducted in the energization path (enlarged flow channels 107, 107, transport channels 101, 101, solution reservoirs 102, 102) connected to the throat 108. and Grow evaporated range while forces the solution interface at a uniform pressure P 0 toward a solution reservoir 102, 102 containing the sex liquid 105 electrodes 104a, of 104b.
  • the narrow portion 103 has the throat portion 108 disposed in the center and the enlarged flow passages 107a and 107b are symmetrical as described above. Therefore, the evaporation speed is the same in both of the enlarged flow passages 107a and 107b. Try to become.
  • the plasma 106 tends to be generated on the negative electrode side 104a. Therefore, it is preferable to connect the pressure adjustment mechanism 110 to the energization path on the positive electrode 104b side.
  • FIG. 14 shows a schematic diagram of another example (Example 4) of the plasma generator 1.
  • an outlet channel 120 and an outlet port 121 are connected to the narrow portion 103 of the plasma generator 1 shown in FIG.
  • a supply pipe 130 (specifically, 130a and 130b) is connected to both of the solution reservoirs 102 and 102 into which the electrodes 104a and 104b are inserted.
  • a supply port 131 for supplying the conductive liquid 105 is connected to the supply pipe 130.
  • both supply pipes 130a and 130b are branched from one supply port 131.
  • the present invention is not limited to this, and the supply pipes 130a and 130b are connected to each other.
  • a separate supply port 131 may be prepared.
  • the throat 108 where the plasma 106 is generated includes two enlarged flow paths 107a and 107b into which the conductive liquid 105 flows from the solution reservoirs 102 and 102 into which the electrodes 104a and 104b are inserted, and the conductive liquid. 105 is connected to an outlet channel 120 that flows out toward the outlet port 121 (hereinafter, the channel to which the outlet port 121 is added is also referred to as a T-type channel).
  • Bubbles generated in the vicinity of the throat portion 108 of the narrow portion 103 push the conductive liquid 105 at a pressure P 0 toward the two enlarged flow passages 107 a and 107 b connected to the narrow portion 103 and the outlet flow passage 120. Try to spread while doing. However, since the outlet channel 120 has a larger channel cross-sectional area than the enlarged channels 107a and 107b on both sides of the throat portion 108 as shown in the figure, the movement resistance of the liquid 105 in the outlet channel 120 is reduced.
  • the supply pipe 130 is preferably configured to be significantly thinner or longer than the transport channels 101 and 101 and the enlarged channels 107a and 107b. More preferably, the supply pipe 130 has a channel cross-sectional area of 1/10 or less, or 10 times or more the length of the transport channels 101 and 101 and the enlarged channels 107a and 107b. Configured.
  • the electrical resistance in the conductive liquid 105 is proportional to the length of the conductive path and inversely proportional to the cross-sectional area of the flow path, the current supply path that can be formed by the supply pipe 130 even when a voltage is applied to the electrodes 104a and 104b. Since the electric resistance is remarkably increased, it is possible to flow electricity only to the path toward the narrow portion 103 without flowing electricity through the path via the supply pipe 130.
  • the voltage applied to the electrodes 104a and 104b may be an AC voltage. This is because if the voltage is changed to an alternating current, it can be expected that a plurality of merits in the following measurement can be enjoyed.
  • a dielectric that is, a substance that behaves as an insulator that does not conduct electricity with respect to a DC voltage
  • a voltage can be applied capacitively. For this reason, it is not necessary to bring the electrodes 104a and 104b into contact with the liquid 105, the structure of the apparatus 1 can be simplified, liquid leakage can be prevented, and contamination of impurities can be prevented. Measurement is possible.
  • FIG. 15 shows a schematic view of another example (Example 5) of the plasma generator 1.
  • the plasma generator 1 shown in FIG. 15 is substantially the same as the fourth embodiment except that the pressure adjusting mechanism 110 is provided in the outlet channel 120.
  • the outlet channel 120 of Example 5 does not need to have a larger channel cross-sectional area than the enlarged channels 107a and 107b on both sides of the throat portion 108 as in the case of Example 4.
  • the outlet channel 120 is provided with the pressure adjusting mechanism 110 as described in the fourth embodiment.
  • the pressure adjustment mechanism 110 includes at least an adjustment pipe 111 and an adjustment container 112 connected to the outlet channel 120.
  • the adjustment container 112 of the present embodiment also contains a gas that is deformed or compressible when the high-pressure conductive liquid 105 flows into and out of the adjustment container 112 as in the previous embodiment.
  • the inside or the periphery of the adjustment vessel 112 can be set to a pressure P 1 lower than the pressure P 0 at the location where the plasma 106 is generated.
  • Pressure adjusting mechanism 110 is provided as described above, it is set to a predetermined pressure P 1 at the time of evaporation, the outlet channel 120 (a portion of the mass) conductive liquid 105 in the vicinity of the pressure adjusting mechanism 110 It will be forcibly sucked. By this forced suction, the moving speed of the conductive liquid 105 remaining in the outlet channel 120 can be adjusted (that is, increased), and evaporation generated in the throat 108 is forced toward the outlet port 121.
  • the progress of evaporation is slowed down in the enlarged flow paths 107a and 107b on the both electrodes 104a and 104b side, and as a result, the plasma 106 in these enlarged flow paths 107a and 107b can be generated for a longer time.
  • FIG. 16A shows a flow path pattern of a T-shaped flow path
  • FIG. 16B shows an enlarged view of a part thereof (that is, a flow path near a narrow portion).
  • the T-type channel is partitioned from a first layer (made of quartz) 201 and a second layer (made of PDMS) 202 laminated on the first layer 201 (see FIG. 17).
  • the first layer 201 can be manufactured by etching.
  • the electrodes 104 a and 104 b can be produced by sputtering platinum and chromium (Pt / Cr) on the surface portion of the first layer 201 corresponding to the bottom surface of the solution reservoir 102.
  • the electrodes 104 and 104 and the second layer 202 can be formed on the bottom surface portion of the solution reservoir 102 by using the SU-8 molding method.
  • the height (depth) of the flow path produced as described above is 100 ⁇ m, and is constant from the supply port 131 to the outlet port 121 of the flow path.
  • the length of the narrow portion 103 is 500 ⁇ m, and the width and length of the solution reservoirs 102 and 102 are 1.5 mm and 3 mm, respectively.
  • the thickness of the electrodes 104 and 104 embedded in the solution reservoirs 102 and 102 is 0.3 ⁇ m.
  • the wire-like electrode 104 is inserted into a tube (not shown) through which the conductive liquid 105 circulates.
  • 105 pressure was easy to escape.
  • the electrodes 104 and 104 are embedded in the bottom surface of the solution reservoir 102, and it is difficult for the conductive liquid 105 to pass through the reservoirs 102 and 102. Therefore, the conductive liquid 105 can flow into the narrow portion 103 while maintaining a desired pressure.
  • the apparatus shown in FIG. 17 includes personal computers 401 and 402, a CCD detector 403, a spectrometer 404, an optical fiber 204, and a high-speed camera 415 as its optical system.
  • the T-type chip including the first layer 201 and the second layer 202 is fixed on the stage 405.
  • the personal computers 401 and 402 and the platinum electrode 407 are connected to a DC power source 407.
  • the sample solution 105 is filled in the syringe 408 and is pushed out by the pump 409 to the fluororesin tube 410 and passes through the T-shaped channel. Thereafter, the sample solution 105 passes through the fluororesin tube 411 and is collected in the collection container 412 as a waste liquid 413.
  • a solution adjusted to a concentration of 0.5 mg / L using an element of lead (Pb), sodium (Na), hydrogen (H wavelength 656 nm), or hydrogen (H wavelength 486 nm) is used. It was. 0.1M nitric acid (HNO 3 ) was used as the solvent.
  • the applied voltage was a pulse voltage of 600 V, the pulse on time was 0.5 ms, and the off time was 9.5 ms.
  • the flow rate for supplying the solution was set to 5 ⁇ L / min.
  • the measurement frequency N of the light emission intensity of each element was 10 times, and the average value was used as the measurement result.
  • FIGS. 18A to 18D show the behavior of the plasma 106 and bubbles observed in the narrow portion 103 of the sixth embodiment.
  • FIGS. 18A and 18B show a state of a pulse having a certain condition at an on time and a state at an off time
  • FIGS. 18C and 18D show an on time of a pulse having another condition. The state at and the state at off time are shown.
  • 18 (A) and 18 (B) it was observed that the gas-liquid interface (BD in the figure) hardly moved even when the on time was switched to the off time (arrow in FIG. 18 (B)). See).
  • FIGS. 18C and 18D when the on-time is switched to the off-time, the gas-liquid interface BD has penetrated into the outlet channel 120, and the movement amount is large. Observed.
  • the condition for applying the pulse voltage affects the interface concentration of elements and the light emission characteristics.
  • the pulse voltage is set so that the water evaporation rate in the narrow portion 103 and the supply speed of the solution 105 to the narrow portion 103 are balanced. It was found that it was necessary to apply.
  • FIG. 19A shows the light emission intensity measured using the flow channel of Example 6.
  • the horizontal axis represents the number obtained by integrating the number of pulses, and the vertical axis represents the integrated emission intensity (arbitrary unit).
  • the number of integrated pulses is small, an increase in emission intensity can be observed as the number of integrated pulses increases. However, if the number of integrated pulses increases, the emission intensity increases even if the number of integrated pulses increases. There is no increase.
  • FIG. 19B is a graph showing the result (also referred to as normalized emission intensity) obtained by dividing each data of FIG. 19A by the data of hydrogen (H wavelength 656 nm) of FIG. 19A.
  • the normalized emission intensity increases in the range of the integrated pulse number from 0 to about 50, and the peak (about 1. 5 times).
  • the solid line shown in the figure is a line showing the tendency of the measurement results of sodium (Na) and lead (Pb) in a range where the number of pulses is small. It is observed that when the cumulative number of pulses exceeds 50, it gradually decreases, and when it exceeds 200, the normalized emission intensity becomes a constant value (about 1). From this result, it can be said that the apparatus of Example 6 was able to realize the interface concentration about 1.5 times with respect to the above elements.
  • Example 6 In order to obtain a higher concentration effect, it is considered effective not only to keep the gas-liquid interface BD for a longer period of time, but also to suppress the generation of vibration at the interface BD as much as possible, as will be described later.
  • the narrow portion 103 of Example 6 is made of soft PDMS, it is assumed that vibration at the interface BD occurred and the concentration rate was not improved so much.
  • FIG. 20A shows a simulation result calculated using the narrow portion 103 made of PDMS in consideration of the influence of vibration at the interface BD.
  • the concentration of the measurement object in the liquid 105 on the inlet side is C o
  • the concentration of the measurement object in the target volume is C b
  • the introduction coefficient of the element M to the plasma 106 at the interface BD is K.
  • solvent evaporates the 0.04NL
  • measurement of the amount obtained by multiplying the C b and K and 0.04NL is introduced into the plasma 106.
  • a solvent 0.04nL at the inlet side the measurement of the amount obtained by multiplying the C o and 0.04nL come into attention volume.
  • the increase in the interface concentration rate can be calculated sequentially for each pulse (see FIG. 20A).
  • the interface concentration ratio becomes 1.5 times the initial value at about 50 pulses, as shown in FIG. 19 (B).
  • the movement due to diffusion is considered to be much smaller than the stirring effect due to vibration, and is ignored.
  • the concentration rate when there is no stirring by vibration can be estimated by simulation (see FIG. 20B). In this case, diffusion due to vibration cannot be ignored. Considering the evaporation rate per pulse using the physical property value of water as the diffusion coefficient, the same calculation as in the above simulation can be performed with the region near the interface BD having approximately 0.005 nL as the target volume ( (See FIG. 20B).
  • the plasma generator of the present invention and the emission spectroscopic analyzer equipped with the plasma generator can be suitably used in fields called microfluid dynamics, ⁇ TAS (micro total analysis systems), and Lab on a chip. According to the present invention, part of particularly necessary functions and structures can be integrated on one plate-like chip.
  • the plasma generation apparatus of the present invention and the emission spectroscopic analysis apparatus equipped with the plasma generation apparatus of the present invention may require a small amount of a specimen (for example, an inorganic component (metal, etc.) in a liquid sample), and are portable, instant, easy to maintain, inexpensive, etc. It has the characteristics of.
  • the apparatus of the present invention can measure a plurality of various inorganic components (such as metal elements) simultaneously. Therefore, the application fields of the present invention include soil inspection and water quality inspection, quality control of manufacturing processes, food inspection (measuring minerals in beverages), confirmation of industrial waste (rare metal, toxic substances), medical blood and urine Applicable to inspection. Due to such applications and advantages, the present invention has very high industrial applicability.

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Abstract

[Problem] To provide a plasma generation device having a long plasma generation time, and an emission spectrophotometer having an extremely high measurement sensitivity. [Solution] A plasma generation device (1) for generating a plasma (106) in an electroconductive liquid (105) has installed therein a transportation channel, formed from an insulating material, for transporting the electroconductive liquid (105). A narrow portion (103) having a cross-section area considerably smaller than that of the transportation channel is installed in the transportation channel. A means for applying an electric field to the narrow portion (103) is installed so that the electric field passes through the narrow portion (103). The present invention is characterized in that the movement resistance of the electroconductive liquid (105) is greater in one portion of the narrow portion (103) than in other portions.

Description

プラズマ発生装置及び発光分光分析装置Plasma generator and emission spectroscopic analyzer
　本発明は、プラズマ発生装置及び発光分光分析装置に関する。さらに詳しくは、溶液中に含まれている元素からの発光スペクトルにより、当該元素の同定と定量とを行うためのプラズマ発生装置及び発光分光分析装置に関する。 The present invention relates to a plasma generator and an emission spectroscopic analyzer. More specifically, the present invention relates to a plasma generation apparatus and an emission spectroscopic analysis apparatus for identifying and quantifying an element based on an emission spectrum from an element contained in a solution.
　近年、半導体プロセスを応用して、ウエハ上に小さな流路や反応容器、分析機器などを作りこみ、１つのチップの上で血液検査などに必要な一通りの化学実験を完遂させようという微小流体デバイス、「μＴＡＳ」や「Ｌａｂ　ｏｎ　ａ　ｃｈｉｐ」と呼ばれる研究分野が急速に発展している。この分野では、高感度の元素分析のために、微小なプラズマを発生させ、そこに霧状の溶液を導入し、元素分析を行う方法が開発されている。 In recent years, microfluids have been developed to apply semiconductor processes to create small flow channels, reaction vessels, analytical instruments, etc. on a wafer and complete a series of chemical experiments necessary for blood testing on a single chip. Research fields called “μTAS” and “Lab on a chip” are rapidly developing. In this field, for high-sensitivity elemental analysis, a method has been developed in which minute plasma is generated and a mist-like solution is introduced therein to perform elemental analysis.
　微小なプラズマとしては、直流プラズマ、容量結合式プラズマ、誘導結合式プラズマ（ＩＣＰ：Inductively Coupled Plasma）などを微小化させたものが知られており、例えば、発光分光分析を行うためのマイクロ化学分析システム（例えば、特許文献１参照）などが提案されている。 As the minute plasma, those obtained by miniaturizing direct current plasma, capacitively coupled plasma, inductively coupled plasma (ICP: Inductively 知 ら Coupled Plasma), etc. are known. For example, microchemical analysis for performing emission spectroscopic analysis A system (see, for example, Patent Document 1) has been proposed.
　しかし、これらのプラズマ発生方法は、ある程度のガス流量が必要であるため大きなボンベを必要としたり、プラズマの発生に大きな電力を必要としたりするという欠点がある。さらに、従来の方法では、検体をプラズマに導入する際にはこの検体を霧状に噴霧するための噴霧器が必要となるが、噴霧器を用いた発光分析装置を小型化することは困難であり、性能のよいものが得られていなかった。 However, these plasma generation methods have a drawback in that a large gas cylinder is required because a certain gas flow rate is required, and that a large electric power is required for generating plasma. Furthermore, in the conventional method, when the specimen is introduced into the plasma, a nebulizer for spraying the specimen in a mist form is necessary, but it is difficult to downsize the emission analyzer using the nebulizer, Good performance was not obtained.
　他のプラズマを発生させる方法として、溶液に電極を挿入し、溶液に直接電流を流すことにより、プラズマを発生させる方法が報告されている（例えば、非特許文献１参照）。 As another method of generating plasma, a method of generating plasma by inserting an electrode into a solution and passing a current directly through the solution has been reported (for example, see Non-Patent Document 1).
　この方法の利点は、溶液中でプラズマが発生し、溶液の蒸発が検体のガス化の働きを担うことから、噴霧器を必要としないことである。しかし、従来の方法では、必ず固体電極がプラズマと接触することから、固体電極に含まれている不純物が蒸発し、その不純物の混入を回避することが困難であるという欠点がある。 The advantage of this method is that plasma is generated in the solution, and the evaporation of the solution plays the role of gasification of the specimen, so that a nebulizer is not required. However, in the conventional method, since the solid electrode always comes into contact with the plasma, the impurities contained in the solid electrode evaporate, and it is difficult to avoid contamination of the impurities.
　これらの従来技術の問題点を克服するため、絶縁性材料で形成された流路に、この流路の断面積よりも著しく小さい断面積を有する狭小部を設け、この流路および狭小部に導電性液体を満たした後、狭小部に電界が通過するようにこの狭小部に電界を印加し、狭小部でプラズマを発生させる液体電極プラズマ（ＬＥＰ：Liquid Electrode Plasma）型発光分光分析装置（以下、単に、ＬＥＰ発光分析装置、ＬＥＰ装置又はＬＥＰと呼ぶ。）が既に提案されている（例えば、特許文献２）。このＬＥＰは、導電性液体中に含まれている元素の発光分析を行う際に、不純物の混入量を少なくしつつ、簡易にプラズマを発生させることができるという利点を有する。また、このＬＥＰは、ＩＣＰ発光分析と同等の性能を持ちながら、装置の小型化、消費ガスや消費電力の劇的減少、及び装置コストの低減を実現するものである。 In order to overcome these problems of the prior art, a narrow portion having a cross-sectional area significantly smaller than the cross-sectional area of the flow channel is provided in the flow channel formed of an insulating material, and the flow channel and the narrow portion are electrically conductive. After filling the liquid, a liquid electrode plasma (LEP: Liquid Electrode Plasma) type emission spectroscopic analyzer (hereinafter referred to as LEP: Liquid Electrode Plasma) type that applies an electric field to the narrow part so that the electric field passes through the narrow part and generates plasma in the narrow part. A simple LEP emission analyzer, LEP device, or LEP) has already been proposed (for example, Patent Document 2). This LEP has an advantage that plasma can be easily generated while reducing the amount of impurities when performing an emission analysis of elements contained in a conductive liquid. In addition, this LEP achieves downsizing of the apparatus, dramatic reduction in consumption gas and power consumption, and reduction in apparatus cost while having performance equivalent to that of ICP emission analysis.
　しかし、この既に提案した従来のＬＥＰは、電極間に高電圧が印加されると電極間に配置された狭小部にてプラズマを発生するが、鉛（Ｐｂ）、タリウム（Ｔｌ）、カドミウム（ｃｄ）などの一部の元素においては十分な光量が得られず、測定感度が低いという課題が残されていた。つまり、既提案の技術のままでは、十分に定量的に測定を行うことのできない元素も存在していた。 However, the conventional LEP already proposed generates plasma in a narrow portion disposed between the electrodes when a high voltage is applied between the electrodes, but lead (Pb), thallium (Tl), cadmium (cd) In some elements such as), a sufficient amount of light cannot be obtained, and there remains a problem that measurement sensitivity is low. In other words, there are elements that cannot be measured quantitatively with the proposed technique.
特開２００２－２５７７８５号公報JP 2002-257785 A 特許第３９３２３６８号公報Japanese Patent No. 3932368
　本発明は、このような従来の実情に鑑みて提案されたものであり、従来の技術が有する欠点を排除したプラズマ発生装置及び発光分光分析装置を提供することを目的とする。すなわち、本発明は、プラズマ発生時間が長いプラズマ発生装置及び測定感度が非常に高い発光分光分析装置を提供することを目的とする。 The present invention has been proposed in view of such conventional circumstances, and an object thereof is to provide a plasma generation apparatus and an emission spectroscopic analysis apparatus that eliminate the disadvantages of the conventional techniques. That is, an object of the present invention is to provide a plasma generation apparatus having a long plasma generation time and an emission spectroscopic analysis apparatus having a very high measurement sensitivity.
　また、本発明は、従来のＬＥＰ発光分析装置に比べ、検出可能な元素を拡大し、微量な元素でも検出・分析が可能な発光分光分析装置を提供することを目的とする。 Another object of the present invention is to provide an emission spectroscopic analyzer capable of detecting and analyzing even a trace amount of elements by expanding the elements that can be detected as compared with conventional LEP emission analyzers.
　本発明者らは、鋭意検討した末、一部の元素においては、短い時間で強制的に電圧を遮断しプラズマの発生時間を短くすると、感度が特に悪くなることに気がついた。さらに、本発明者らは、この感度低下の原因を究明するとともに感度低下を解消する方法についても見出した。これらについて以下に詳述する。 As a result of intensive studies, the present inventors have found that for some elements, the sensitivity is particularly poor when the voltage is forcibly cut off in a short time and the plasma generation time is shortened. Furthermore, the present inventors have found out a cause of this sensitivity decrease and also found out a method for eliminating the sensitivity decrease. These are described in detail below.
（界面濃縮効果について）
　プラズマ発生に伴い、気体と液体との界面では、液体中の物質がプラズマ中に入る（以下、「気化」と呼ぶ。）一方、気化しにくいものは液体中に取り残される。取り残されたものは、気化し易いもの（例えば、水等）の蒸発に伴い、界面の液体側に溜まっていき、すなわち濃縮される。これを「界面濃縮効果」と呼ぶ。界面での濃縮により、その元素がプラズマ中に入る確率が増え、すなわち気化する量も増え、やがてプラズマ中に入ってくる。これにより、感度が改善することが見込まれる。 (About the interface concentration effect)
As the plasma is generated, substances in the liquid enter the plasma (hereinafter referred to as “vaporization”) at the interface between the gas and the liquid, while those that are difficult to vaporize are left behind in the liquid. What is left behind accumulates on the liquid side of the interface, that is, is concentrated, as a material that is easily vaporized (for example, water) evaporates. This is called the “interface concentration effect”. Concentration at the interface increases the probability that the element enters the plasma, that is, the amount of vaporization increases, and eventually enters the plasma. This is expected to improve sensitivity.
（特定の元素における測定感度が低下する原因の検討）
　ところが、プラズマの発生時間が短いと一般に界面濃縮効果が低い。これが一部の元素においてプラズマの発生時間が短いと特に測定感度が低い原因の一つであると考えられる。界面濃縮効果を引き出すには、プラズマ発生時間を長くすることが有効である。しかしながら、長時間電圧を印加してもプラズマ発生時間が短くなってしまう傾向があった。この傾向の要因は、気泡及びプラズマの発生により、気泡及びプラズマの圧力が上昇し、それにより電界をプラズマに印加する役割をもつ界面が、狭小部より外側へ押しやられ、プラズマを維持する条件が満たされなくなることによるものと推察される。 (Examination of the cause of decrease in measurement sensitivity of specific elements)
However, when the plasma generation time is short, the interface concentration effect is generally low. This is considered to be one of the causes that the measurement sensitivity is particularly low when the plasma generation time is short in some elements. In order to bring out the interface concentration effect, it is effective to lengthen the plasma generation time. However, even when a voltage is applied for a long time, the plasma generation time tends to be shortened. The cause of this tendency is that the pressure of the bubble and the plasma increases due to the generation of the bubble and the plasma, whereby the interface having a role of applying an electric field to the plasma is pushed outward from the narrow portion, and the condition for maintaining the plasma is It is presumed that it is due to being no longer satisfied.
（上記課題の解決に向けた手法・手段の検討）
　従って、プラズマの発生時間を長くするためには、プラズマに電界を印加する役割をもつ界面の移動を遅くすることが有効である。なお、直流電圧を印加するプラズマでは、正極側の発光現象と負極側の発光現象とに差があることがよく知られている。そこで、本発明者らは、より強く発光する側の界面の移動を特に遅くすれば、測定対象の元素がより長く測定部に留まり、測定感度が良くなることを期待した。具体的には、界面の移動を遅くするには、流路抵抗を高くしたり、液体の慣性力を大きくしたりすることが有効であると本発明者らは考えた。ここでは、これら２つのパラメータを含めた液体の移動のし易さを「移動抵抗」と呼ぶ。 (Examination of methods and means for solving the above problems)
Therefore, in order to lengthen the plasma generation time, it is effective to slow the movement of the interface having a role of applying an electric field to the plasma. It is well known that there is a difference between the light emission phenomenon on the positive electrode side and the light emission phenomenon on the negative electrode side in the plasma to which a DC voltage is applied. Therefore, the present inventors expected that if the movement of the interface on the side that emits light more strongly is slowed down, the element to be measured stays in the measurement section longer and the measurement sensitivity is improved. Specifically, the present inventors considered that it is effective to increase the channel resistance or increase the inertial force of the liquid in order to slow the movement of the interface. Here, the ease of movement of the liquid including these two parameters is called “movement resistance”.
　また、本発明者らは、圧力を積極的に逃がすことも特定の界面の移動抑制に有効であると考え、この為には、発光やプラズマの維持への寄与の少ない界面（つまり、上記特定の界面とは異なる別の界面）を積極的に移動させることが有効であると考えた。 In addition, the present inventors consider that positive pressure release is also effective in suppressing movement of a specific interface, and for this purpose, an interface that has little contribution to light emission and plasma maintenance (that is, the above-mentioned specific specification). We thought that it is effective to actively move a different interface).
　上記の考えを具体的に実現するにあたって、本発明者らは、圧力を積極的に逃がすため、第３・第４の流路を狭小部に接続し、その移動抵抗を小さくし、同時に電圧を印加する役割をもった流路の移動抵抗を大きくすることによって、狭小部内でのプラズマ発生時間を長くさせることができることにも想到し、本発明を完成するに至った。 In concretely realizing the above idea, the inventors of the present invention connected the third and fourth flow paths to a narrow portion to reduce the movement resistance in order to release the pressure positively, and simultaneously reduce the voltage. It has also been conceived that the plasma generation time in the narrow portion can be extended by increasing the movement resistance of the flow path having the role of applying, and the present invention has been completed.
　さらに、本発明者らは、狭小部内で流路断面積が最も狭い最狭小流路両端に形成された拡大流路における流体の移動抵抗に差が現れるようにすることも有効であり、例えば、最狭小流路両端の拡大流路を従来の対称な構造から非対称な構造に形成すれば、一方の電極側への界面の移動速度が他方の電極側へのそれと比べて遅くさせ得ることや界面濃縮が起こる時間や領域を増加させ得ることを見出し、本発明を完成するに至った。 Furthermore, the present inventors are also effective to make a difference appear in the fluid movement resistance in the enlarged flow channel formed at both ends of the narrowest narrow channel with the narrowest channel cross-sectional area in the narrow portion, for example, If the enlarged flow path at both ends of the narrowest flow path is formed from a conventional symmetrical structure to an asymmetrical structure, the moving speed of the interface to one electrode side can be made slower than that to the other electrode side. It has been found that the time and region where concentration occurs can be increased, and the present invention has been completed.
　すなわち、本発明は、例えば、次の構成・特徴を採用するものである。
（態様１）
　導電性液体中でプラズマを発生させるプラズマ発生装置であって、
　前記導電性液体を運搬しかつ絶縁性材料で形成された運搬流路と、
　前記運搬流路に接続されかつ該運搬流路の断面積よりも著しく小さい断面積を有する狭小部と、
　前記狭小部に電界が通過するように該狭小部に電界を印加するための手段と、
　を備え、かつ、
　前記狭小部の一部分では、他の部分に比較して前記導電性液体の移動抵抗が大きいことを特徴とするプラズマ発生装置。
（態様２）
　前記狭小部には、流路断面積が最も小さい喉部と、該喉部の両側に前記運搬流路に接続する拡大流路とが形成され、
　一側の前記拡大流路では、他側の前記拡大流路に比較して前記導電性液体の移動抵抗が大きいことを特徴とする態様１記載のプラズマ発生装置。
（態様３）
　前記拡大流路が前記喉部を基点として非対称に構成されていることを特徴とする態様２記載のプラズマ発生装置。
（態様４）
　前記喉部は前記狭小部の一端よりも他端近くに配設され、
　前記拡大流路は前記喉部から前記運搬流路に向かって次第に拡大する流路断面積を有し、
　前記一端側に配設された前記拡大流路の最大流路断面積は前記他端側に配設された前記拡大流路の最大流路断面積よりも大きく、
　前記一端側に配設された前記拡大流路では、前記他端側に配設された前記拡大流路に比較して前記導電性液体の移動抵抗が大きいことを特徴とする態様３記載のプラズマ発生装置。
（態様５）
　前記一端側に配設された前記拡大流路の前記最大流路断面積は前記喉部での前記流路断面積の１．１～１００倍であり、前記他端側に配設された前記拡大流路の前記最大流路断面積は前記喉部の断面積の１．１～５０倍であることを特徴とする態様４記載のプラズマ発生装置。
（態様６）
　前記狭小部に、前記導電性液体の圧力を局所的に増加又は減少させる圧力調整機構がさらに配設されていることを特徴とする態様１～５のいずれか１項記載のプラズマ発生装置。
（態様７）
　導電性液体中でプラズマを発生させるプラズマ発生装置であって、
　前記導電性液体を運搬しかつ絶縁性材料で形成された運搬流路と、
　前記運搬流路に接続されかつ該運搬流路の断面積よりも著しく小さい断面積を有する狭小部と、
　前記狭小部に電界が通過するように該狭小部に電界を印加するための手段と、
　を備え、かつ、
　前記狭小部には出口流路がさらに配設され、
　前記導電性液体を、前記運搬流路から前記狭小部に流入しかつ前記狭小部を経由して前記出口流路から流出するように案内し、
　前記出口流路の断面積が前記狭小部の前記断面積よりも大きくするか、或いは前記出口流路に前記導電性液体の圧力を局所的に増加又は減少させる圧力調整機構がさらに配設されることで、前記狭小部の少なくとも一部分において、前記出口流路に比較して前記導電性液体の移動抵抗が大きくなることを特徴とするプラズマ発生装置。
（態様８）
　前記狭小部に電界を印加するための前記手段は、電極が挿入された溶液リザーバと、該溶液リザーバに前記導電性液体を供給する供給管と、を備え、かつ、
　前記供給管の長さが前記運搬流路の長さの１０倍以上であるか、又は、前記供給管の断面積が、前記運搬流路の断面積の１０分の１以下であることを特徴とする態様１～７のいずれか１項記載のプラズマ発生装置。
（態様９）
　前記狭小部に電界を印加するために交流電圧が用いられることを特徴とする態様１～８のいずれか１項記載のプラズマ発生装置。
（態様１０）
　導電性液体中でプラズマを発生させるプラズマ発生装置であって、
　前記導電性液体を運搬しかつ絶縁性材料で形成された運搬流路と、
　前記運搬流路中に配置されかつ該運搬流路の断面積よりも著しく小さい断面積を有する狭小部と、
　前記狭小部に電界が通過するように該狭小部に電界を印加するための手段と、
　を備え、かつ、
　前記手段にはマイナス電極とプラス電極とを含み、
　前記狭小部には、流路断面積が最も小さい喉部と、前記喉部の一方の開口部に接続されかつ流路長さが互いに異なる拡大流路とが形成され、
　前記流路長さが大きい前記拡大流路は、前記プラズマを発生させる元素の種類に応じて、前記マイナス電極又は前記プラス電極のいずれかの側に配置されるよう構成したことを特徴とするプラズマ発生装置。
（態様１１）
　導電性液体中でプラズマを発生させるプラズマ発生装置であって、
　前記導電性液体を運搬しかつ絶縁性材料で形成された運搬流路と、
　前記運搬流路に接続されかつ該運搬流路の断面積よりも著しく小さい断面積を有する狭小部と、
　前記狭小部に電界が通過するように該狭小部に電界を印加するための電極と、
　を備え、かつ、
　前記狭小部には出口流路がさらに配設され、
　前記導電性液体を、前記運搬流路から前記狭小部に流入しかつ前記狭小部を経由して前記出口流路から流出するように案内し、
　前記狭小部への前記液体の供給速度と、前記狭小部での前記液体の蒸発速度とが釣り合うように前記電界が印加されていることを特徴とするプラズマ発生装置。
（態様１２）
　態様１～１１のいずれか１項記載のプラズマ発生装置を備えた発光分光分析装置。 That is, the present invention employs, for example, the following configurations / features.
(Aspect 1)
A plasma generator for generating plasma in a conductive liquid,
A transport channel for transporting the conductive liquid and formed of an insulating material;
A narrow portion connected to the transport channel and having a cross-sectional area significantly smaller than the cross-sectional area of the transport channel;
Means for applying an electric field to the narrow portion so that the electric field passes through the narrow portion;
And having
The plasma generating apparatus according to claim 1, wherein a movement resistance of the conductive liquid is larger in a part of the narrow part than in another part.
(Aspect 2)
The narrow portion is formed with a throat portion having the smallest channel cross-sectional area, and enlarged channels connected to the transport channel on both sides of the throat portion,
2. The plasma generating apparatus according to aspect 1, wherein the enlarged flow channel on one side has a larger movement resistance of the conductive liquid than the enlarged flow channel on the other side.
(Aspect 3)
The plasma generating apparatus according to aspect 2, wherein the enlarged flow path is configured asymmetrically with respect to the throat.
(Aspect 4)
The throat is disposed closer to the other end than one end of the narrow portion;
The enlarged channel has a channel cross-sectional area that gradually expands from the throat toward the transport channel,
The maximum channel cross-sectional area of the expanded channel disposed on the one end side is larger than the maximum channel cross-sectional area of the expanded channel disposed on the other end side,
4. The plasma according to claim 3, wherein the expansion flow path disposed on the one end side has a larger movement resistance of the conductive liquid than the expansion flow path disposed on the other end side. Generator.
(Aspect 5)
The maximum flow path cross-sectional area of the enlarged flow path disposed on the one end side is 1.1 to 100 times the flow path cross-sectional area at the throat portion, and the flow path cross-sectional area disposed on the other end side is 5. The plasma generating apparatus according to aspect 4, wherein the maximum flow path cross-sectional area of the enlarged flow path is 1.1 to 50 times the cross-sectional area of the throat.
(Aspect 6)
6. The plasma generating apparatus according to claim 1, further comprising a pressure adjusting mechanism that locally increases or decreases the pressure of the conductive liquid in the narrow portion.
(Aspect 7)
A plasma generator for generating plasma in a conductive liquid,
A transport channel for transporting the conductive liquid and formed of an insulating material;
A narrow portion connected to the transport channel and having a cross-sectional area significantly smaller than the cross-sectional area of the transport channel;
Means for applying an electric field to the narrow portion so that the electric field passes through the narrow portion;
And having
An outlet channel is further disposed in the narrow portion,
Guiding the conductive liquid so as to flow into the narrow portion from the transport channel and out of the outlet channel via the narrow portion;
A pressure adjusting mechanism for increasing or decreasing the pressure of the conductive liquid locally is provided in the outlet channel, or a sectional area of the outlet channel is made larger than the sectional area of the narrow portion. Thus, in at least a part of the narrow portion, the movement resistance of the conductive liquid is increased as compared with the outlet channel.
(Aspect 8)
The means for applying an electric field to the narrow portion includes a solution reservoir in which an electrode is inserted, and a supply pipe for supplying the conductive liquid to the solution reservoir, and
The length of the supply pipe is not less than 10 times the length of the transport flow path, or the cross-sectional area of the supply pipe is 1/10 or less of the cross-sectional area of the transport flow path. 8. The plasma generator according to any one of aspects 1 to 7.
(Aspect 9)
9. The plasma generator according to any one of aspects 1 to 8, wherein an alternating voltage is used to apply an electric field to the narrow portion.
(Aspect 10)
A plasma generator for generating plasma in a conductive liquid,
A transport channel for transporting the conductive liquid and formed of an insulating material;
A narrow portion disposed in the transport channel and having a cross-sectional area significantly smaller than the cross-sectional area of the transport channel;
Means for applying an electric field to the narrow portion so that the electric field passes through the narrow portion;
And having
The means includes a negative electrode and a positive electrode,
The narrow portion is formed with a throat portion having the smallest channel cross-sectional area and an enlarged channel that is connected to one opening of the throat portion and has different channel lengths.
The expanded channel having a large channel length is configured to be arranged on either the minus electrode or the plus electrode depending on the type of element that generates the plasma. Generator.
(Aspect 11)
A plasma generator for generating plasma in a conductive liquid,
A transport channel for transporting the conductive liquid and formed of an insulating material;
A narrow portion connected to the transport channel and having a cross-sectional area significantly smaller than the cross-sectional area of the transport channel;
An electrode for applying an electric field to the narrow portion so that the electric field passes through the narrow portion;
And having
An outlet channel is further disposed in the narrow portion,
Guiding the conductive liquid so as to flow into the narrow portion from the transport channel and out of the outlet channel via the narrow portion;
The plasma generator according to claim 1, wherein the electric field is applied so that a supply speed of the liquid to the narrow portion and an evaporation speed of the liquid in the narrow portion are balanced.
(Aspect 12)
An emission spectroscopic analysis apparatus comprising the plasma generator according to any one of embodiments 1 to 11.
　ここで、狭小部とは、運搬流路中に設けられかつ該運搬流路より流路断面積が著しく小さい流路のことを指す。狭小部は、流路断面積が最も小さい喉部と、この喉部両側に設けられかつ喉部と運搬流路とを接続する拡大流路を備えることが好ましい。拡大流路の断面積は喉部から運搬流路に向かって徐々に拡大していく末広がりの流路がさらに好ましい。本発明のある態様においては、拡大流路が喉部を基点として非対称な流路構造となることが好ましい。さらに、喉部の断面積を１とすると、一方の拡大流路の端部断面積は約１．１～１００倍とし、他方の拡大流路の端部断面積は約１．１～５０倍とするような非対称の狭小部を構成することが好ましい。 Here, the narrow portion refers to a channel provided in the transport channel and having a significantly smaller channel cross-sectional area than the transport channel. The narrow portion preferably includes a throat portion having the smallest channel cross-sectional area, and an enlarged channel provided on both sides of the throat portion and connecting the throat portion and the transport channel. The cross-sectional area of the enlarged channel is more preferably a divergent channel that gradually expands from the throat toward the transport channel. In an aspect of the present invention, it is preferable that the enlarged flow path has an asymmetric flow path structure with the throat as a starting point. Further, assuming that the cross-sectional area of the throat is 1, the end cross-sectional area of one enlarged flow path is about 1.1 to 100 times, and the end cross-sectional area of the other enlarged flow path is about 1.1 to 50 times. It is preferable to constitute an asymmetric narrow portion such as
　ここで、上述した導電性液体の移動抵抗の用語・意味について説明する。図２１に示すように、ある流路（流路面積Ｓ、流路長さＬ、ｃは流路コンダクタンス、ｃ１は定数）に液体が満たされ、所定の圧力（一端と他端との圧力差をΔＰ）が掛けられた時の流路内の液体（質量ｍ、密度ρ）の移動のしやすさは、流路の形状で定まる流体抵抗、速度ｖと時間ｔとで表現される加速度、液体の慣性、等のパラメータにより決定される（図２１中の数式（１）～（５）を参照）。このように、本明細書では、液体の移動のしやすさを移動抵抗と表現する。例えば、流路が非対称であれば、この流路内の液体の移動抵抗にも差が生じると考えられる。 Here, the term and meaning of the above-described movement resistance of the conductive liquid will be described. As shown in FIG. 21, a certain flow path (flow path area S, flow path length L, c is flow path conductance, c 1 is a constant) is filled with liquid, and a predetermined pressure (pressure between one end and the other end) is obtained. The ease of movement of the liquid (mass m, density ρ) in the channel when the difference is multiplied by ΔP) is the acceleration expressed by the fluid resistance, speed v and time t determined by the shape of the channel. , The inertia of the liquid, and the like (see equations (1) to (5) in FIG. 21). Thus, in this specification, the ease of movement of the liquid is expressed as movement resistance. For example, if the flow path is asymmetric, it is considered that there is a difference in the movement resistance of the liquid in the flow path.
　絶縁性材料として、例えば、ガラス、ポリエチレン、ポリプロピレンなどのオレフィン系樹脂、ポリジメチルシロキサンなどのシリコーン、フッ素樹脂、セラミックスなどが挙げられるが、本発明は、かかる例示のみに限定されるものではない。 Examples of the insulating material include olefinic resins such as glass, polyethylene, and polypropylene, silicones such as polydimethylsiloxane, fluororesins, and ceramics, but the present invention is not limited to such examples.
　なお、流路（運搬流路や狭小部内の流路）は、例えば、絶縁性材料からなる板状のチップやプレート上に、リソグラフィ技術を用いて形成させることができる。 Note that the flow path (transport flow path or flow path in the narrow portion) can be formed on a plate-shaped chip or plate made of an insulating material using a lithography technique, for example.
　また、狭小部として、例えば、運搬流路に着脱可能に配設しうる形状を有する成形体（大量生産が可能な射出成形法などにより作製可能）を用意しても良く、使用後に新しいもの（新品の狭小部）と適宜交換になり、カートリッジ的に使用することができる。 Moreover, as the narrow portion, for example, a molded body having a shape that can be detachably disposed in the transport channel (can be manufactured by an injection molding method capable of mass production) may be prepared. It can be replaced with a new narrow part as appropriate and used as a cartridge.
　流路および狭小部に満たされる導電性液体として、分析対象の液体試料が用いられる。導電性液体に用いられる電解質としては、例えば、硝酸、酢酸、塩酸などが挙げられるが、これらのなかでは、分析に障害を発生させがたい特徴を有する硝酸が好ましい。試料は、種々の材料が測定可能であるが、硝酸など分析に支障を生じない元素からなる電解質で導電性を付与できるものが好ましい。 The liquid sample to be analyzed is used as the conductive liquid that fills the channel and the narrow part. Examples of the electrolyte used for the conductive liquid include nitric acid, acetic acid, hydrochloric acid, and the like. Among these, nitric acid having characteristics that do not easily cause an obstacle to analysis is preferable. As the sample, various materials can be measured, but an electrolyte made of an element such as nitric acid that does not interfere with analysis is preferable.
　次に、狭小部に電界が通過するように、例えば、狭小部に沿って電界を印加するなどの方法により、狭小部に電界を印加する。これにより、狭小部で気泡が生じ、この気泡中にプラズマを発生させることができる。 Next, an electric field is applied to the narrow portion by a method such as applying an electric field along the narrow portion so that the electric field passes through the narrow portion. Thereby, bubbles are generated in the narrow portion, and plasma can be generated in the bubbles.
　本発明のプラズマ発生装置を備えた発光分光分析装置では、特許文献２で提案された従来装置に比して４～１０倍程度の発光強度が得られるため、非常に感度が高い元素分析が可能となる。例えば、狭小部として所定寸法の非対称流路を用い、導電性液体として鉛（Ｐｂ）が１００ｐｐｍ混入した０．１Ｍの硝酸水溶液を用いて元素分析を実施したところ、発光波長４０６ｎｍにて同一条件の従来装置に比して約１０倍の発光強度（従来装置では約８００（任意単位）に対し、本発明の装置では約８０００（任意単位））を示した。 In the emission spectroscopic analyzer equipped with the plasma generator of the present invention, the emission intensity is about 4 to 10 times that of the conventional apparatus proposed in Patent Document 2, so that elemental analysis with extremely high sensitivity is possible. It becomes. For example, when an elemental analysis was performed using an asymmetric flow path of a predetermined size as a narrow portion and a 0.1 M nitric acid aqueous solution mixed with 100 ppm of lead (Pb) as a conductive liquid, the same conditions were obtained at an emission wavelength of 406 nm. The emission intensity was about 10 times that of the conventional device (about 800 (arbitrary unit) for the conventional device and about 8000 (arbitrary unit) for the device of the present invention).
本発明のプラズマ発生装置の主要部を説明した図である。（実施例１）It is a figure explaining the principal part of the plasma generator of this invention. Example 1 狭小部の好適な構成を説明した図である。（実施例１）It is a figure explaining the suitable structure of a narrow part. Example 1 本発明の発光分光分析装置の構成を説明した図である。（実施例２）It is a figure explaining the structure of the emission-spectral-analysis apparatus of this invention. (Example 2) 実施例２の装置を用いて測定した発光強度を示した図である。FIG. 4 is a graph showing light emission intensity measured using the apparatus of Example 2. 実施例２の装置を用いて測定した発光強度を示した図である。FIG. 4 is a graph showing light emission intensity measured using the apparatus of Example 2. 実施例２の装置を用いて測定した発光強度を示した図である。FIG. 4 is a graph showing light emission intensity measured using the apparatus of Example 2. 実施例２の装置を用いて測定した発光強度を示した図である。FIG. 4 is a graph showing light emission intensity measured using the apparatus of Example 2. 元素と発光強度との関係を示した図である。It is the figure which showed the relationship between an element and emitted light intensity. 従来装置（ＩＣＰ装置）におけるプラズマへの元素の導入過程を示した図である。It is the figure which showed the introduction process of the element to the plasma in a conventional apparatus (ICP apparatus). ＬＥＰ装置におけるプラズマへの元素の導入過程を示した図である。It is the figure which showed the introduction process of the element to the plasma in a LEP apparatus. 界面濃度の経時変化と、元素導入速度の経時変化と、を示した図である。It is the figure which showed the time-dependent change of interface concentration, and the time-dependent change of element introduction | transduction speed | rate. 非対称流路Ｂ、対称流路Ａ、及び非対称流路Ｃを使用した場合の発光強度と検量線を示す。The light emission intensity and the calibration curve when the asymmetric channel B, the symmetric channel A, and the asymmetric channel C are used are shown. 別例のプラズマ発生装置を説明した図である。（実施例３）It is the figure explaining the plasma generator of another example. (Example 3) 別例のプラズマ発生装置を説明した図である。（実施例４）It is the figure explaining the plasma generator of another example. Example 4 別例のプラズマ発生装置を説明した図である。（実施例５）It is the figure explaining the plasma generator of another example. (Example 5) 実施例６の流路パターンを示した図である。It is the figure which showed the flow-path pattern of Example 6. 実施例６における発光分光分析装置の構成を説明した図である。It is the figure explaining the structure of the emission-spectral-analysis apparatus in Example 6. FIG. 実施例６でのプラズマ及び気泡の挙動を示した図である。It is the figure which showed the behavior of the plasma and bubble in Example 6. 実施例６の装置を用いて測定した発光強度を示した図である。It is the figure which showed the emitted light intensity measured using the apparatus of Example 6. FIG. 積算パルス数と界面濃縮率との関係及び積算パルス数とプラズマへの元素導入率との関係を示したシミュレーション結果である。It is the simulation result which showed the relationship between the integration pulse number and the interface concentration rate, and the relationship between the integration pulse number and the element introduction rate to the plasma. ある流路内のある液体の移動抵抗について説明した図である。It is a figure explaining movement resistance of a certain liquid in a certain channel.
　以下、本発明を図面に示す実施の形態に基づき説明するが、本発明は、下記の具体的な実施形態に何等限定されるものではない。 Hereinafter, the present invention will be described based on the embodiments shown in the drawings, but the present invention is not limited to the following specific embodiments.
（プラズマ発生装置の基本構成）
　本発明のプラズマ発生装置の一例（実施例１）を図１に示す。実施例１のプラズマ発生装置１は、図１に示すように、２つの溶液リザーバ１０２を備えている。各溶液リザーバ１０２，１０２には開口部が設けられており、この開口部から電極１０４（具体的には、１０４ａ，１０４ｂ）が溶液リザーバ１０２，１０２内に挿入されている。２つの溶液リザーバ１０２，１０２は、狭小部１０３に隔てられた運搬流路１０１，１０１を介して互いに接続されている。なお、狭小部１０３はプラズマ発生装置１に着脱可能に配設されることが好ましい。 (Basic configuration of plasma generator)
An example (Example 1) of the plasma generator of the present invention is shown in FIG. The plasma generator 1 of Example 1 includes two solution reservoirs 102 as shown in FIG. Each solution reservoir 102, 102 is provided with an opening, and an electrode 104 (specifically, 104a, 104b) is inserted into the solution reservoir 102, 102 from this opening. The two solution reservoirs 102, 102 are connected to each other via transport channels 101, 101 separated by a narrow portion 103. The narrow portion 103 is preferably detachably disposed on the plasma generator 1.
　また、運搬流路１０１，１０１、狭小部１０３、溶液リザーバ１０２，１０２の壁面は絶縁性材料で形成されている。運搬流路１０１，１０１と狭小部１０３は、２つの溶液リザーバ１０２，１０２が導電性液体１０５（以下、単に液体、溶液とも呼ぶ。）で満たされることで導電性液体１０５を閉じ込めるとともに、電極１０４ａ，１０４ｂに電圧を印加することで狭小部１０３付近にて電界を生成する。この際に、両側を運搬流路１０１，１０１に接続された狭小部１０３は他の部分（運搬流路１０１，１０１や溶液リザーバ１０２，１０２）の流路断面積より小さな流路断面積を有するため、この狭小部１０３（特に、喉部１０８）では、電流と電界の集中が起こり、他の部分１０１，１０２よりも温度が高くなり、沸騰やプラズマ１０６の発生が起こり易くなる。 The wall surfaces of the transport channels 101 and 101, the narrow portion 103, and the solution reservoirs 102 and 102 are formed of an insulating material. The conveyance channels 101 and 101 and the narrow portion 103 confine the conductive liquid 105 when the two solution reservoirs 102 and 102 are filled with the conductive liquid 105 (hereinafter, also simply referred to as liquid or solution), and the electrode 104a. , 104b, an electric field is generated in the vicinity of the narrow portion 103 by applying a voltage. At this time, the narrow portion 103 connected to the transport channels 101, 101 on both sides has a channel cross-sectional area smaller than the channel cross-sectional area of other parts (the transport channels 101, 101 and the solution reservoirs 102, 102). Therefore, in this narrow portion 103 (particularly the throat portion 108), current and electric field are concentrated, the temperature becomes higher than the other portions 101 and 102, and boiling and plasma 106 are likely to occur.
　導電性液体１０５は、測定対象となる元素を含み、かつ導電性を有している必要がある。導電性液体１０５に導電性を付与するために、通常、電解質（支持塩）が用いられる。電解質のなかでは、硝酸は、その構成元素が大気中に含まれているものと水に含まれているものであるとともに、金属を良く溶かす性質を有するので適当である。なお、導電性液体１０５の液温は、特に限定されないが、通常、１５～４０℃、好ましくは２０～２５℃程度であることが望ましい。 The conductive liquid 105 needs to contain an element to be measured and have conductivity. In order to impart conductivity to the conductive liquid 105, an electrolyte (supporting salt) is usually used. Among electrolytes, nitric acid is suitable because its constituent elements are contained in the air and in water, and it has a property of dissolving metals well. The liquid temperature of the conductive liquid 105 is not particularly limited, but is usually 15 to 40 ° C., preferably about 20 to 25 ° C.
　電極１０４に用いられる材料としては、電流を流すことによって腐食が生じにくい白金などの貴金属やカーボンなどが好適である。この一対の電極１０４ａ、１０４ｂ間に電圧を印加することにより、狭小部１０３では電流と電界の集中が生じることから、気泡が生じ、生じた気泡中にプラズマ１０６が発生する。このプラズマ１０６からの光を分光することにより、導電性液体１０５の元素分析を容易に行うことができる。 The material used for the electrode 104 is preferably a noble metal such as platinum or carbon that is unlikely to be corroded by passing an electric current. By applying a voltage between the pair of electrodes 104a and 104b, current and electric field are concentrated in the narrow portion 103, so that bubbles are generated, and plasma 106 is generated in the generated bubbles. By analyzing the light from the plasma 106, elemental analysis of the conductive liquid 105 can be easily performed.
（狭小部内の非対称流路構造）
　上述したプラズマ発生装置１の基本的な構成や原理は、本発明者が既に提案した特許文献２に開示したところであるが、既提案とは異なる本発明（実施例１）の特徴の一つは、運搬流路１０１，１０１に接続された狭小部１０３の内部構造が非対称に形成されている点である。これに対して、特許文献２に開示の技術では、狭小部１０３の流路全長のほぼ中間に流路断面積が最も狭い喉部１０８が配置され、この喉部１０８を中心に対称な拡大流路１０７，１０７が形成されていた。言い換えれば、喉部１０８両端で同一であった流路断面積がどちらの電極１０４，１０４側にもほぼ同様割合で拡大する流路が形成されていた。 (Asymmetric channel structure in narrow part)
The basic configuration and principle of the plasma generator 1 described above are disclosed in Patent Document 2 already proposed by the present inventor. One of the features of the present invention (Example 1) that is different from the already proposed one is as follows. The internal structure of the narrow portion 103 connected to the transport channels 101 and 101 is asymmetrically formed. On the other hand, in the technique disclosed in Patent Document 2, the throat portion 108 having the narrowest channel cross-sectional area is arranged approximately in the middle of the entire channel length of the narrow portion 103, and a symmetrical enlarged flow around the throat portion 108. Paths 107 and 107 were formed. In other words, a channel in which the channel cross-sectional area, which was the same at both ends of the throat 108, expands at substantially the same rate on either electrode 104, 104 side was formed.
　これに対し、本発明の実施例１では狭小部１０３内に喉部１０８に形成されるものの、この喉部１０８は狭小部１０３の一端１０９ａよりも他端１０９ｂ近くに偏って配置され、喉部１０８両側では流路容積や流路断面積（及びその拡大率）が異なる非対称な拡大流路１０７ａ，１０７ｂが形成されている。これにより、一方の拡大流路１０７ａ内に閉じ込められている導電性液体１０５の質量は、他方の拡大流路１０７ｂ内に閉じ込められている導電性液体１０５の質量よりも大きくなる。また、喉部１０８を基点に発生した蒸発（ひいてはプラズマ１０６）領域は両方向に伝播・進展していくことになるが、質量の大きな導電性液体１０５を閉じ込めている拡大流路１０７ａ内では導電性液体１０５の移動抵抗が大きくなる。従って、拡大流路１０７ａにおける導電性液体１０５のプラズマ発生時間が他の拡大流路１０７ｂでのそれに比して長くなる。これにより、一方の拡大流路１０７ａにおける界面濃縮効果が高まり、そこに存在する分析対象元素の気化量も増大するため、その元素の測定感度も向上させることができる。 On the other hand, in the first embodiment of the present invention, the throat portion 108 is formed in the narrow portion 103, but the throat portion 108 is disposed closer to the other end 109b than the one end 109a of the narrow portion 103, and the throat portion On both sides 108, asymmetric enlarged flow passages 107a and 107b having different flow passage volumes and flow passage sectional areas (and enlargement ratios) are formed. As a result, the mass of the conductive liquid 105 confined in one enlarged flow path 107a is larger than the mass of the conductive liquid 105 confined in the other enlarged flow path 107b. In addition, the evaporation (and thus the plasma 106) region generated from the throat 108 propagates and propagates in both directions. However, in the expanded flow path 107a confining the conductive liquid 105 having a large mass, the conductivity is increased. The movement resistance of the liquid 105 is increased. Therefore, the plasma generation time of the conductive liquid 105 in the enlarged flow path 107a is longer than that in the other enlarged flow paths 107b. As a result, the interface concentration effect in the one enlarged flow path 107a is enhanced, and the amount of vaporization of the analysis target element existing there is also increased, so that the measurement sensitivity of the element can be improved.
　以上の説明から、実施例１の狭小部１０３内の非対称構造は、喉部１０８両側において界面濃縮効果に差を生みだすための一手段といえる。図２は狭小部１０３内の好適な構成を例示する。図２（Ａ）は、水平方向（図１では紙面に対して垂直方向）において破断した狭小部１０３の断面図であり、図２（Ｂ）は垂直方向（図１では紙面に平行な方向）において破断した狭小部１０３の断面図である。 From the above description, it can be said that the asymmetric structure in the narrow portion 103 of Example 1 is a means for producing a difference in the interface concentration effect on both sides of the throat portion 108. FIG. 2 illustrates a preferred configuration within the narrow portion 103. 2A is a cross-sectional view of the narrow portion 103 fractured in the horizontal direction (perpendicular to the paper surface in FIG. 1), and FIG. 2B is the vertical direction (the direction parallel to the paper surface in FIG. 1). It is sectional drawing of the narrow part 103 fractured | ruptured in FIG.
　図２に示す例では、狭小部１０３は１８００μｍの長さＬを有し、水平方向に一定の２２０μｍの幅Ｗを有する。しかしながら、垂直方向の幅（つまり流路高さ）は長さ方向に変化しており、一端１０９ａでは４００μｍ（流路高さＨａ）であり、他端１０９ｂでは１００μｍ（流路高さＨｂ）である。喉部１０８の設置位置は、従来技術のように狭小部１０３の中央（いずれかの端から９００μｍ）ではなく、いずれかの端の方に偏った位置（図２の例では、一端１０９ａから１５００μｍ（距離Ｌａ）、他端１０９ｂから３００μｍ（距離Ｌｂ）だけ離れた位置）となっていることに留意されたい。 In the example shown in FIG. 2, the narrow portion 103 has a length L of 1800 μm and a constant width W of 220 μm in the horizontal direction. However, the vertical width (that is, the channel height) changes in the length direction, and is 400 μm (channel height H a ) at one end 109a and 100 μm (channel height H b ) at the other end 109b. ). The position of the throat 108 is not the center of the narrow portion 103 (900 μm from either end) as in the prior art, but is a position biased toward either end (in the example of FIG. 2, from one end 109 a to 1500 μm). Note that (distance L a ), 300 μm (distance L b ) away from the other end 109b).
　ここで、狭小部１０３は喉部１０８両側の拡大流路１０７ａ，１０７ｂで非対称的に流路断面積が変化していることになる。非対称性の度合として、喉部１０８での流路断面積に対して、端１０９ｂでの流路断面積を１．１～５０倍程度に設定し、かつ、端１０９ａでの流路断面積を１．１倍～１００倍程度に設定することが好ましい。 Here, in the narrow portion 103, the channel cross-sectional area is changed asymmetrically between the enlarged channels 107a and 107b on both sides of the throat 108. As the degree of asymmetry, the channel cross-sectional area at the end 109b is set to about 1.1 to 50 times the channel cross-sectional area at the throat 108, and the channel cross-sectional area at the end 109a is set to about 1.1 to 50 times. It is preferable to set to about 1.1 times to 100 times.
　本発明のプラズマの発生装置１が用いられた発光分光分析装置２の一例（実施例２）を図３に示す。図３に示された装置２は、フォトセンサを用いてプラズマ発光を検出し、電力供給を制御する発光分光分析装置である。 FIG. 3 shows an example (Example 2) of an emission spectroscopic analyzer 2 in which the plasma generator 1 of the present invention is used. The apparatus 2 shown in FIG. 3 is an emission spectroscopic analysis apparatus that detects plasma emission using a photosensor and controls power supply.
　石英ガラス２０１上には、ポリジメチルシロキサン（以下、ＰＤＭＳという）などの絶縁性材料で作製され、狭小部１０３がパターニングされているシート状のチップ２０２が載置されている。チップ２０２は、フォトリソグラフィーにより、レジスト材の流路パターンを型取りすることによって製造されている。チップ２０２は、石英ガラス２０１上に置くことにより、自然に密着し、微小流路を形成する。チップ２０２には、運搬流路１０１の端にあたる部分にパンチなどの窄孔用機器を用いて孔を開けることにより、溶液リザーバ１０２が形成されている。 On the quartz glass 201, a sheet-like chip 202 made of an insulating material such as polydimethylsiloxane (hereinafter referred to as PDMS) and patterned with a narrow portion 103 is placed. The chip 202 is manufactured by taking a flow path pattern of a resist material by photolithography. By placing the chip 202 on the quartz glass 201, the chip 202 naturally adheres to form a microchannel. In the tip 202, a solution reservoir 102 is formed by opening a hole in a portion corresponding to the end of the transport channel 101 by using a narrow hole device such as a punch.
　導電性液体１０５として、例えば、生理的条件のリン酸バッファーを１／２０（容量比）に薄めたものが挙げられる。電極１０４，１０４として、例えば直径が０．５ｍｍの白金線が挙げられる。狭小部１０３に電界が通過して該狭小部１０３に電界を印加するために、電源３０１と接続された電極１０４，１０４が溶液リザーバ１０２，１０２に挿入される。なお、ワイヤ状の電極１０４，１０４は、一般に、導電性液体１０５を供給する管（図示せず）内を通して溶液リザーバ１０２，１０２に挿入される。 Examples of the conductive liquid 105 include a liquid obtained by diluting a physiological condition phosphate buffer to 1/20 (volume ratio). Examples of the electrodes 104 and 104 include platinum wires having a diameter of 0.5 mm. In order to pass an electric field through the narrow portion 103 and apply an electric field to the narrow portion 103, electrodes 104 and 104 connected to the power source 301 are inserted into the solution reservoirs 102 and 102. The wire- like electrodes 104 and 104 are generally inserted into the solution reservoirs 102 and 102 through a pipe (not shown) that supplies the conductive liquid 105.
　電極１０４，１０４へ、例えば、３００～１５００Ｖの電圧を印加すると、狭小部１０３にプラズマ１０６が発生する。プラズマ１０６からの光を光ファイバー２０４に導入し、分光器３０４（例えば、オーシャンオプティクス社製：ＵＳＢ２０００）でスペクトルを測定し、測定したデータをコンピュータ３０５で収集・解析等することにより、発光分光分析を行うことができる。 For example, when a voltage of 300 to 1500 V is applied to the electrodes 104 and 104, a plasma 106 is generated in the narrow portion 103. The light from the plasma 106 is introduced into the optical fiber 204, the spectrum is measured with a spectroscope 304 (for example, USB2000 manufactured by Ocean Optics), and the measured data is collected and analyzed by a computer 305 to perform emission spectroscopic analysis. It can be carried out.
　プラズマ１０６により発生する光は、チップ２０２の下部に配設されたフォトセンサユニット３０２に内蔵されているフォトセンサ（図示せず）で捉えられる。フォトセンサユニット３０２は、フォトセンサで捉えられた発光強度に基づいて、スイッチ３０３による電界の接続および切断を制御し、プラズマ１０６の発生から指定時間の後に電界の印加を止めることにより、発光強度、発光時間および発光回数を制御することができる。 The light generated by the plasma 106 is captured by a photosensor (not shown) built in the photosensor unit 302 disposed below the chip 202. The photo sensor unit 302 controls the connection and disconnection of the electric field by the switch 303 based on the light emission intensity captured by the photo sensor, and stops the application of the electric field after a specified time from the generation of the plasma 106, whereby the light emission intensity, The light emission time and the number of times of light emission can be controlled.
　（第１評価試験　狭小部流路構造と発光強度との関係）
　上述のような構成の発光分光分析装置２を用いて導電性液体１０５中に含まれる金属元素の発光強度を測定した（以下、第１評価試験と呼ぶ）。測定対象として、喉部１０８を基点として非対称な拡大流路１０７ａ，１０７ｂを備えた本発明の狭小部１０３と、喉部１０８を基点として対称な流路を備えた従来の狭小部（比較例）とを用意し、これらの測定結果を対比した。狭小部１０３や溶液リザーバ１０２の周囲を取り囲むチップ２０２の材料には石英を用いた。また、プラス側電極１０４ｂ及びマイナス側電極１０４ａとして直径０．５ｍｍの白金線を用い、これらの電極１０４ａ，１０４ｂ間に７００Ｖ～９５０Ｖ程度の電圧を間欠的に印加した（具体的には、電圧オン時間３ｍｓ（ミリ秒）、電圧オフ時間２ｍｓを１周期として１０回繰り返すパルス状の印加を実施した）。 (First Evaluation Test Relationship between narrow channel structure and light emission intensity)
The emission intensity of the metal element contained in the conductive liquid 105 was measured using the emission spectroscopic analyzer 2 having the above-described configuration (hereinafter referred to as a first evaluation test). As a measurement object, the narrow portion 103 of the present invention having the asymmetric enlarged flow passages 107a and 107b with the throat portion 108 as a base point, and the conventional narrow portion with a symmetrical flow passage with the throat portion 108 as a base point (comparative example). Were prepared and these measurement results were compared. Quartz was used as the material of the chip 202 surrounding the narrow portion 103 and the solution reservoir 102. Further, a platinum wire having a diameter of 0.5 mm was used as the plus side electrode 104b and the minus side electrode 104a, and a voltage of about 700 V to 950 V was intermittently applied between these electrodes 104a and 104b (specifically, voltage on (Pulse application was repeated 10 times with a period of 3 ms (milliseconds) and a voltage off time of 2 ms).
　ここで比較例１として、流路長さ全長（Ｌ＝１８００μｍ）に亘って一定の流路幅（Ｗ＝２２０μｍ）を有し、流路長さＬの中央（つまり両端から９００μｍの位置）に喉部１０８が形成され、流路高さがこの喉部１０８位置でＨｔｈ＝５０μｍ、両端１０９ａ，１０９ｂ位置でＨａ＝Ｈｂ＝１００μｍとなる対称な狭小部１０３を用いた。 Here, as Comparative Example 1, the channel has a constant channel width (W = 220 μm) over the entire channel length (L = 1800 μm), and is at the center of the channel length L (that is, 900 μm from both ends). A throat portion 108 is formed, and a symmetrical narrow portion 103 is used in which the flow path height is H th = 50 μm at the position of the throat portion 108 and H a = H b = 100 μm at the positions of both ends 109a and 109b.
　これに対して、本発明（実施例１）の狭小部１０３も同様に流路長さ全長（Ｌ＝１８００μｍ）に亘って一定の流路幅（Ｗ＝２２０μｍ）を有するものの、流路高さＨｔｈ＝５０μｍを有した喉部１０８が流路高さＨａ＝４００μｍを有した一端１０９ａから１５００μｍ離れるとともに流路高さＨｂ＝１００μｍを有した他端１０９ｂから３００μｍ離れて設置されており、狭小部１０３は非対称流路を構成する。 On the other hand, the narrow portion 103 of the present invention (Example 1) similarly has a constant channel width (W = 220 μm) over the entire channel length (L = 1800 μm), but the channel height. The throat portion 108 having H th = 50 μm is set 1500 μm away from one end 109 a having a flow path height H a = 400 μm and 300 μm away from the other end 109 b having a flow path height H b = 100 μm. The narrow portion 103 constitutes an asymmetric channel.
　導電性液体１０５には、測定対象となる遷移金属元素（鉛１００ｍｇ／Ｌ（つまり、１００ｐｐｍのＰｂ）若しくはタリウム１０ｍｇ／Ｌ（つまり、１０ｐｐｍのＴｌ））又はアルカリ金属元素（カリウム１００ｍｇ／Ｌ（つまり、１００ｐｐｍのＫ）若しくはナトリウム５ｍｇ／Ｌ（つまり、５ｐｐｍのＮａ））を混入した。溶媒として０．１Ｍの硝酸（ＨＮＯ３）の水溶液を用いた。 The conductive liquid 105 includes a transition metal element to be measured (lead 100 mg / L (that is, 100 ppm Pb) or thallium 10 mg / L (that is, 10 ppm Tl)) or an alkali metal element (potassium 100 mg / L (that is, 100 ppm K) or sodium 5 mg / L (ie 5 ppm Na)). An aqueous solution of 0.1 M nitric acid (HNO 3 ) was used as the solvent.
　図４の各グラフは、印加電圧の値に対応した鉛（Ｐｂ，４０６ｎｍ）の発光強度（任意単位）の変化を示す。ここで、図４（Ａ）は狭小部１０３内の拡大流路１０７，１０７が対称な比較例を用いた場合の発光量（任意単位であり、明細書中では発光強度とも呼ぶ。）の変化を示し、図４（Ｂ）及び（Ｃ）は、狭小部１０３内の拡大流路１０７，１０７が非対称な本実施例２を用いた場合の発光量を示す。 Each graph in FIG. 4 shows the change in the emission intensity (arbitrary unit) of lead (Pb, 406 nm) corresponding to the value of the applied voltage. Here, FIG. 4A shows a change in light emission amount (which is an arbitrary unit and is also referred to as light emission intensity in the specification) when the comparative example in which the enlarged flow paths 107 and 107 in the narrow portion 103 are symmetrical is used. 4B and 4C show the amount of light emitted when the present Example 2 in which the enlarged flow paths 107 and 107 in the narrow portion 103 are asymmetric is used.
　なお、装置１に着脱可能な狭小部１０３を利用したため、電極１０４ａ，１０４ｂに対して狭小部１０３の端部１０９ａ，１０９ｂの設置位置を変更して評価を行った。図４（Ｂ）は、より小さい流路高さＨｂを有した端部１０９ｂがマイナス電極側１０４ａに向き、より大きな流路高さＨａを有した端部１０９ａをプラス電極１０４ｂ側に向くように狭小部１０３を設置した構成（以下、「実施例１Ｂ」とも呼ぶ。）の測定結果である。これに対し、図４（Ｃ）は、より小さい流路高さＨｂを有した端部１０９ｂがプラス電極側１０４ｂに向き、より大きな流路高さＨａを有した端部１０９ａをマイナス電極１０４ａ側に向くように狭小部１０３を設置した構成（以下、「実施例１Ｃ」とも呼ぶ。）の測定結果である。 Since the narrow portion 103 that can be attached to and detached from the apparatus 1 was used, evaluation was performed by changing the installation positions of the end portions 109a and 109b of the narrow portion 103 with respect to the electrodes 104a and 104b. In FIG. 4B , an end 109b having a smaller flow path height Hb is directed to the negative electrode side 104a, and an end 109a having a larger flow path height Ha is directed to the positive electrode 104b side. The measurement results of the configuration in which the narrow portion 103 is installed (hereinafter also referred to as “Example 1B”). On the other hand, FIG. 4C shows that the end 109b having a smaller flow path height Hb is directed to the positive electrode side 104b, and the end 109a having a larger flow path height H a is a negative electrode. It is a measurement result of the structure (henceforth "Example 1C") which installed the narrow part 103 so that it may face 104a side.
　なお、後述する図５、６、７の（Ａ）、（Ｂ）、（Ｃ）については、供した導電性液体１０５の種類が異なるだけで、狭小部１０３の流路構成・配置ついては図４の（Ａ）、（Ｂ）、（Ｃ）の場合と同様であり、各図の（Ａ）、（Ｂ）、（Ｃ）に示す狭小部１０３の流路構成・配置の条件は対応している。よって、これらについての再度の説明は省略する。 5, (A), (B), and (C) in FIGS. 5, 6, and 7 to be described later, only the kind of the provided conductive liquid 105 is different, and the flow path configuration and arrangement of the narrow portion 103 are shown in FIG. (A), (B), and (C) are the same, and the flow path configuration and arrangement conditions of the narrow portion 103 shown in (A), (B), and (C) of each figure correspond to each other. Yes. Therefore, the re-explanation about these is omitted.
　図５の各グラフは、印加電圧の値に応じたタリウム（Ｔｌ，５３５ｎｍ）の発光強度の変化を示す。図４及び図５に示された結果から明らかなように、電圧が増加するに伴い発光強度は上昇している。なお、図４（Ｂ）の実施例１Ｂの場合は、図４（Ａ）の比較例１の場合に比べて印加電圧を高くしても発光強度の増加率はやや低いのに対し、図４（Ｃ）の実施例１Ｃの場合は、図４（Ａ）に比べて発光強度の増加率は著しく高い。また、タリウムＴｌを使用した図５の場合の実施例１Ｃと実施例１Ｂとの場合でも、図４の実施例１Ｃと実施例１Ｂとの場合で現われた各傾向と同様の傾向がそれぞれ表れていることがわかる。 Each graph of FIG. 5 shows the change in the emission intensity of thallium (Tl, 535 nm) according to the value of the applied voltage. As is apparent from the results shown in FIGS. 4 and 5, the emission intensity increases as the voltage increases. In the case of Example 1B in FIG. 4B, the increase rate of the emission intensity is slightly lower even when the applied voltage is increased compared to the case of Comparative Example 1 in FIG. In the case of Example 1C in (C), the rate of increase in emission intensity is significantly higher than that in FIG. In addition, even in the case of Example 1C and Example 1B in the case of FIG. 5 using thallium Tl, the same tendency as that shown in the case of Example 1C and Example 1B in FIG. 4 appears. I understand that.
　上記結果を得た理由として、遷移金属元素が混入した導電性液体１０５はマイナス電極１０４ａ側に蒸発し易いこと、さらに図４（Ｃ）や図５（Ｃ）に使用した狭小部１０３は、喉部１０８からマイナス電極１０４ａ側の流路端１０９ａまでの距離Ｌａや流路高さＨａが長くなっていることが挙げられる。つまり、図４（Ｃ）や図５（Ｃ）に使用した狭小部１０３の構成では、導電性液体１０５の局所的な移動抵抗が増大するため、プラズマ１０６の発生がより長時間存続しやすく、上記側での界面濃縮効果が高まり、ひいては、上記側付近に存在する上記元素の測定感度が上昇したものと考えられる。 The reason for obtaining the above result is that the conductive liquid 105 mixed with the transition metal element easily evaporates on the negative electrode 104a side, and the narrow portion 103 used in FIGS. distance L a and channel height H a from part 108 to the flow path end 109a of the negative electrode 104a side may be mentioned that is longer. That is, in the configuration of the narrow portion 103 used in FIGS. 4C and 5C, the local movement resistance of the conductive liquid 105 is increased, so that the generation of the plasma 106 is likely to continue for a long time. It is considered that the interface concentration effect on the above side is enhanced, and as a result, the measurement sensitivity of the element existing in the vicinity of the side is increased.
　図６に印加電圧の値に応じたカリウム（Ｋ，７６６ｎｍ）の発光強度の変化を示す。また、図７に印加電圧の値に応じたナトリウム（Ｎａ，５８９ｎｍ）の発光強度の変化を示す。図６及び図７に示すように、どの流路構成でも、印加される電圧が増加するに伴い発光強度は上がっている。実施例１Ｂ及び実施例１Ｃの発光強度の増加は、いずれの場合も、対応する比較例１のそれよりも高い。 FIG. 6 shows changes in the emission intensity of potassium (K, 766 nm) according to the value of the applied voltage. FIG. 7 shows a change in the emission intensity of sodium (Na, 589 nm) according to the value of the applied voltage. As shown in FIGS. 6 and 7, the light emission intensity increases as the applied voltage increases in any flow path configuration. The increase in emission intensity of Example 1B and Example 1C is higher than that of the corresponding Comparative Example 1 in any case.
　なお、図６及び７における実施例１Ｂの場合では非常に高い発光強度を得たが、測定結果のばらつきも大きかった。図６及び図７で示した測定対象の元素は、後述するように、もともと発光し易い元素であり、非対称流路構造が発光へ与える影響のみを顕著に反映するものではないからであると考えられる。 In addition, in the case of Example 1B in FIGS. 6 and 7, a very high emission intensity was obtained, but the variation in the measurement results was also large. The element to be measured shown in FIG. 6 and FIG. 7 is an element that easily emits light, as will be described later, and does not significantly reflect only the influence of the asymmetric channel structure on light emission. It is done.
　以上説明したように、本実施例の狭小部１０３内の非対称構造は、喉部１０８両側の拡大流路１０７ａ，１０７ｂにおいて界面濃縮効果に差を生みだすための一手段といえる。 As described above, the asymmetric structure in the narrow portion 103 of this embodiment can be said to be a means for producing a difference in the interface concentration effect in the enlarged flow passages 107a and 107b on both sides of the throat portion.
（ＬＥＰを使用する際の分析対象の元素について）
　本発明者らは、図４及び図５の測定結果と、図６及び図７の測定結果と、が異なる傾向を示したため、測定対象の元素をＬＥＰで測定した場合に元素の発光のし易さの観点から３つのグループに分けて、これらの傾向の違いを考えることとした。 (Elements to be analyzed when using LEP)
Since the measurement results of FIGS. 4 and 5 and the measurement results of FIGS. 6 and 7 showed different tendencies, the inventors of the present invention easily emit light when the element to be measured is measured by LEP. From this point of view, we decided to divide into three groups and consider the difference between these trends.
（１）電圧の印加時間が短くてもよく光る元素のグループ（第１グループ）
　第１グループに属する元素は、従来のＬＥＰ装置を使用しても、従来のＩＣＰ装置と同等に発光する元素であり、例えば、ナトリウム（Ｎａ）、カリウム（Ｋ）、リチウム（Ｌｉ）、銀（Ａｇ）などが挙げられる。 (1) Group of elements that shine even when the voltage application time is short (first group)
The element belonging to the first group is an element that emits light as much as the conventional ICP device even when the conventional LEP device is used. For example, sodium (Na), potassium (K), lithium (Li), silver ( Ag) and the like.
（２）電圧の印加時間を長くしないと光らない元素のグループ（第２グループ）
　第２グループに属する元素は、従来のＬＥＰ装置を使用して当該元素を発光させると、従来のＩＣＰ装置の使用時に比べてその発光強度が極端に低くなってしまう元素であり、例えば、鉛（Ｐｂ）、Ｔｌ（タリウム）、カドミウム（Ｃｄ）などの重金属が挙げられる。 (2) Group of elements that do not shine unless voltage application time is increased (second group)
An element belonging to the second group is an element whose emission intensity becomes extremely lower than that when using a conventional ICP device when the element is caused to emit light using a conventional LEP device. Heavy metals such as Pb), Tl (thallium), and cadmium (Cd).
（３）電圧を長時間、印加してもほとんど光らない元素のグループ（第３グループ）
　第３グループに属する元素は、原子化できていない元素であり、従来のＬＥＰ装置にて長時間、電圧を印加しても殆ど光らない元素であり、例えば、アルミニウム（Ａｌ）、ジルコニウム（Ｚｒ）などが挙げられる。 (3) Group of elements that hardly emit light even when voltage is applied for a long time (third group)
The element belonging to the third group is an element that has not been atomized, and is an element that hardly emits light even when a voltage is applied for a long time with a conventional LEP device. For example, aluminum (Al), zirconium (Zr) Etc.
　なお、図８は、各グループを代表する各元素に、従来のＬＥＰ装置を使って一定の電圧（７００Ｖ）を印加したときの発光強度の経時変化を示す。第１グループの一例として２ｐｐｍのナトリウム（Ｎａ）を使用し、第２グループの一例として４０ｐｐｍの鉛（Ｐｂ）を使用し、第３グループの一例として１００ｐｐｍのジルコニウム（Ｚｒ）を使用した。この図８からも以下の点が観察された。すなわち、ナトリウム（Ｎａ）は印加時間が短くてもよく光る。一方、鉛（Ｐｂ）は印加時間を長くすれば光る。なお、ジルコニウム（Ｚｒ）は印加時間に長短に関係なく、殆ど光らない。 FIG. 8 shows the change over time in the emission intensity when a constant voltage (700 V) is applied to each element representing each group using a conventional LEP device. An example of the first group was 2 ppm sodium (Na), an example of the second group was 40 ppm lead (Pb), and an example of the third group was 100 ppm zirconium (Zr). The following points were also observed from FIG. That is, sodium (Na) shines even if the application time is short. On the other hand, lead (Pb) shines if the application time is lengthened. Zirconium (Zr) hardly emits light regardless of the application time.
　従来のＬＥＰ装置が、従来のＩＣＰ装置と異なり、適用する元素によって以上のような感度の違いが表れた理由として、ＩＣＰ装置とＬＥＰ装置とでは、元素がプラズマに入る過程が決定的に異なっていると本発明者らは考察した。 The conventional LEP device differs from the conventional ICP device in that the difference in sensitivity as described above appears depending on the element to be applied. In the ICP device and the LEP device, the process of entering the plasma is decisively different. The present inventors have considered.
　（ＩＣＰ装置におけるプラズマへの元素の導入過程）
　ＩＣＰ装置では、図９（Ａ）に示すように、測定元素（図９中の符号Ｍ）を含んだ溶液１１は、アルゴン等のキャリアガス１２とともに噴霧器１３によって管１４ａの上流側に噴霧される。水分１５も別の入口１６，１７より管１４ｂ，１４ｃに導入される。なお、管１４ａ，１４ｂ，１４ｃは入れ子状を成し、各管１４ａ，１４ｂ，１４ｃの下流側で各管内の流れが合流する。管１４ｃの外周に巻き付けられたコイル１８によって管１４ｃの下流側にて測定元素Ｍや水分１５が加熱されてから、測定元素Ｍはプラズマ１０６中に導入される（つまり、気化される）こととなる。すなわち、図９（Ｂ）に示すように、測定元素Ｍは水滴Ｗに包含されるが、次第にその周囲の水滴Ｗが蒸発するため、どの測定元素Ｍも最終的には必ずプラズマ１０６中に導入されることとなる。 (Introduction process of elements to plasma in ICP equipment)
In the ICP apparatus, as shown in FIG. 9A, the solution 11 containing the measurement element (symbol M in FIG. 9) is sprayed to the upstream side of the tube 14a by the sprayer 13 together with the carrier gas 12 such as argon. . Moisture 15 is also introduced into the tubes 14b, 14c from the other inlets 16,17. The tubes 14a, 14b, and 14c are nested, and the flows in the tubes merge on the downstream side of the tubes 14a, 14b, and 14c. The measurement element M and the moisture 15 are heated on the downstream side of the tube 14c by the coil 18 wound around the outer periphery of the tube 14c, and then the measurement element M is introduced into the plasma 106 (that is, vaporized). Become. That is, as shown in FIG. 9B, the measurement element M is included in the water droplet W, but since the surrounding water droplets W gradually evaporate, any measurement element M is finally introduced into the plasma 106 without fail. Will be.
　（ＬＥＰ装置におけるプラズマへの元素の導入過程）
　これに対し、本発明の装置１のようなＬＥＰ型の装置では、図１０（Ａ）に示すように、狭小部１０３にプラズマ１０６を発生させると、プラズマ１０６は図１０（Ａ）中の矢印の方向に移動して、溶液１０５界面にプラズマ１０６が衝突する（以下、プラズマ１０６のスパッタ作用とも呼ぶ）。これによって、測定元素Ｍがプラズマ１０６中に入り（つまり気化し）、発光することになる。つまり、プラズマ１０６に入りにくい第２グループに属する元素Ｍは、溶液１０５中に残ったままとなりやすい。そこで、第２グループに属する元素Ｍを第１グループに属する元素Ｍと同等に発光させるには界面濃縮効果を利用することが有効ではないかと本発明者らは考えた。 (Introduction process of elements into plasma in LEP equipment)
On the other hand, in the LEP type apparatus such as the apparatus 1 of the present invention, as shown in FIG. 10A, when the plasma 106 is generated in the narrow portion 103, the plasma 106 is changed to an arrow in FIG. The plasma 106 collides with the interface of the solution 105 (hereinafter also referred to as the sputtering action of the plasma 106). As a result, the measurement element M enters the plasma 106 (that is, vaporizes) and emits light. That is, the element M belonging to the second group that is difficult to enter the plasma 106 tends to remain in the solution 105. Therefore, the present inventors considered that it is effective to use the interface concentration effect to cause the element M belonging to the second group to emit light in the same manner as the element M belonging to the first group.
　（界面濃縮とプラズマへの元素の導入との関係）
　図１０（Ｂ）は、狭小部１０３に発生したプラズマ１０６と、これに接する溶液１０５の一部とを簡略化したモデルを示す。このモデルは、説明の便宜のため、溶液１０５には流れが無い（つまり、流速が零である）単純なモデルを仮定する。なお、溶液１０５中の元素Ｍの濃度をＣｏと表記する。一方、プラズマ１０６と溶液１０５との境界を画す界面付近の溶液１０５部分（図１０（Ｂ）中破線で示した領域ＡＢＤ）の元素の濃度をＣｂと表記する。図１０（Ｂ）中の符号Ｖと矢印は、溶媒の蒸発による界面の移動速度とその移動方向を示す。 (Relationship between interface concentration and introduction of elements into plasma)
FIG. 10B shows a simplified model of the plasma 106 generated in the narrow portion 103 and a part of the solution 105 in contact therewith. For convenience of explanation, this model assumes a simple model in which the solution 105 has no flow (that is, the flow rate is zero). It is noted that the concentration of the element M in the solution 105 is denoted as C o. On the other hand, the element concentration in the portion of the solution 105 in the vicinity of the interface that defines the boundary between the plasma 106 and the solution 105 (region A BD indicated by a broken line in FIG. 10B) is denoted as Cb. A symbol V and an arrow in FIG. 10B indicate the moving speed and moving direction of the interface due to evaporation of the solvent.
　この界面付近の領域ＡＢＤが図１０（Ｂ）の下段の位置まで移動したと仮定した場合、この領域ＡＢＤでの元素Ｍの濃度の収支バランスは、以下の数式で表すことができる。 In this case the vicinity of the interface region A BD is assumed to move to a lower position of FIG. 10 (B), balance balance of concentration of the element M in this area A BD can be expressed by the following equation.
Figure JPOXMLDOC01-appb-M000001
Figure JPOXMLDOC01-appb-M000001
　なお、数式中のＫはプラズマ１０６への元素Ｍの導入のしやすさを表すプラズマ導入係数である。界面付近での元素Ｍの濃度Ｃｂの時間変化は、濃度Ｃｏの領域ＡＢＤの移動速度（ＶＣｏ）から、単位時間あたりに界面からプラズマ１０６へ導入される元素Ｍの導入速度（ＣｂＫ）を差し引いたものであることをこの数式は意味する。上記数式のモデルから以下の点が導き出せる。 Note that K in the equation is a plasma introduction coefficient representing the ease of introduction of the element M into the plasma 106. Time variation of the concentration C b of the element M in the vicinity of the interface, the concentration C from o the moving speed of the area A BD of (VC o), introduction rate of the element M is introduced from the interface into the plasma 106 per unit time (C This equation means that b K) is subtracted. The following points can be derived from the above mathematical model.
　図１１は、界面付近の濃度Ｃｂの経時変化及び元素の導入速度ＣｂＫの経時変化を示す。左側の縦軸は界面付近の濃度Ｃｂを示し、右側の縦軸は元素導入速度ＣｂＫを示す。界面（つまり、界面付近の領域ＡＢＤ）の濃度Ｃｂは、図１１中の上側の曲線に示すように、時間が経過すると、ある一定の値（つまり、左軸に示すＣｏ（Ｖ／Ｋ））に近づく。また、プラズマ１０６への元素Ｍの導入速度ＣｂＫも、図１１中の下側の曲線に示すように、時間の経過とともに界面濃縮が十分に進めば、プラズマ導入係数Ｋに依らず、一定の値（つまり、右軸に示すＶＣｏ）に漸近していくことが分かる。 Figure 11 shows the time course of the introduction rate of C b K of aging and elemental concentration C b in the vicinity of the interface. The left vertical axis represents the concentration C b in the vicinity of the interface, the right vertical axis indicates the element introduction rate C b K. As shown by the upper curve in FIG. 11, the concentration C b of the interface (that is, the region A BD near the interface) is a certain value (that is, C o (V / K)) is approached. Further, the introduction rate C b K of the element M into the plasma 106 is also constant regardless of the plasma introduction coefficient K if the interface concentration sufficiently progresses with time as shown in the lower curve in FIG. It can be seen that the value gradually approaches the value of (ie, VC o shown on the right axis).
　この図１１の結果より、第２グループに属する発光しにくい元素Ｍであっても、界面濃縮を促進しつつ電圧を長時間印加しやすい流路構成をＬＥＰの狭小部１０３に採用できれば、ＬＥＰ形式の装置であっても、実用的なレベルの発光強度にてその元素Ｍを発光できることが期待できる。 From the result shown in FIG. 11, even if the element M belonging to the second group is difficult to emit light, if the channel configuration that facilitates application of a voltage for a long time while promoting interface concentration can be adopted in the narrow portion 103 of the LEP, This device can be expected to emit the element M with a practical level of light emission intensity.
　界面濃縮を増強する方法の一つとして、上述したように、非対称な流路構造を狭小部１０３に採用することが考えられる。より好適には、負極側１０４ａの拡大流路１０７ａを正極側１０４ｂの拡大流路１０７ｂより長くした構造を採用する。このような流路構造を採用する理由は、電圧を印加すると、一番狭い喉部１０８で気泡とプラズマ１０６とが発生する。上述したプラズマ１０６のスパッタ作用は負極側１０４ａで起こることが本発明者らの経験上分かっている。プラズマ１０６への元素Ｍの導入が主に上記スパッタ作用によるものであるならば、負極側１０４ａから元素Ｍがプラズマ１０６に導入すると考えられる。この考えが正しければ、負極側１０４ａの拡大流路１０７ａをより長くすることで、界面濃縮をより長い距離でより長い時間、起こすことができる。 As one of the methods for enhancing the interfacial concentration, it is conceivable to adopt an asymmetric channel structure for the narrow portion 103 as described above. More preferably, a structure in which the enlarged flow path 107a on the negative electrode side 104a is longer than the enlarged flow path 107b on the positive electrode side 104b is adopted. The reason for adopting such a flow channel structure is that when a voltage is applied, bubbles and plasma 106 are generated in the narrowest throat 108. Our experience has shown that the sputtering action of the plasma 106 described above occurs on the negative electrode side 104a. If the introduction of the element M into the plasma 106 is mainly due to the sputtering action, it is considered that the element M is introduced into the plasma 106 from the negative electrode side 104a. If this idea is correct, it is possible to cause interfacial concentration at a longer distance and for a longer time by making the enlarged flow path 107a on the negative electrode side 104a longer.
　（第２評価試験：感度と検出限界の評価）
　評価用の狭小部１０３として、対称流路Ａ、正極１０４ｂ側の流路が負極１０４ａ側の流路より長くした非対称流路Ｂと、負極１０４ａ側の流路が正極１０４ｂ側の流路より長くした非対称流路Ｃと、の３つを用意した。そして、狭小部１０３をプラズマ発生装置１に載置し、測定元素Ｍの濃度を変化させて、各条件での感度と検出限界との違いを評価した。 (Second evaluation test: Evaluation of sensitivity and detection limit)
As the narrow portion 103 for evaluation, the symmetrical channel A, the asymmetric channel B in which the channel on the positive electrode 104b side is longer than the channel on the negative electrode 104a side, and the channel on the negative electrode 104a side are longer than the channel on the positive electrode 104b side. The asymmetric flow path C was prepared. And the narrow part 103 was mounted in the plasma generator 1, the density | concentration of the measurement element M was changed, and the difference between the sensitivity and detection limit in each condition was evaluated.
　（第２評価試験用の試料）
　対称流路Ａ、非対称流路Ｂ、及び非対称流路Ｃは、それぞれ、第１評価試験で使用した比較例１、実施例１Ｂ、及び実施例１Ｃで説明した流路構造と同様であり、それぞれ石英製である。図４の場合と同様に、測定元素として鉛（Ｐｂ）を用い、溶媒として０．１Ｍの硝酸（ＨＮＯ３）の水溶液を用いた。また、鉛（Ｐｂ）標準液を上記溶媒で希釈して所定の濃度（０ｍｇ／Ｌ，１０ｍｇ／Ｌ，２０ｍｇ／Ｌ，４０ｍｇ／Ｌ，６０ｍｇ／Ｌ，８０ｍｇ／Ｌ，１００ｍｇ／Ｌ）の試料溶液１０５を調整した。なお、それぞれの溶液リザーバ１０２，１０２には試料溶液１０５を４０Ｌずつ注入した。 (Sample for second evaluation test)
The symmetric flow path A, the asymmetric flow path B, and the asymmetric flow path C are the same as the flow path structures described in Comparative Example 1, Example 1B, and Example 1C used in the first evaluation test, respectively. Made of quartz. As in the case of FIG. 4, lead (Pb) was used as the measurement element, and an aqueous solution of 0.1 M nitric acid (HNO 3 ) was used as the solvent. Moreover, a lead (Pb) standard solution is diluted with the above-mentioned solvent, and sample solutions of predetermined concentrations (0 mg / L, 10 mg / L, 20 mg / L, 40 mg / L, 60 mg / L, 80 mg / L, 100 mg / L) 105 was adjusted. Note that 40 L of sample solution 105 was injected into each of the solution reservoirs 102 and 102.
　（第２評価試験での測定条件）
　電極１０４ａ，１０４ｂ間に間欠的に印加する印加電圧を９００Ｖに設定し、電圧オン時間５ｍsと電圧オフ時間６０ｍｓとをから構成されるパルス状の電圧を４０回繰り返し、与えた。鉛（Ｐｂ）の強発光ピーク波長は４０５．７８２ｎｍであった。 (Measurement conditions in the second evaluation test)
An applied voltage intermittently applied between the electrodes 104a and 104b was set to 900 V, and a pulsed voltage composed of a voltage on time of 5 ms and a voltage off time of 60 ms was repeatedly applied 40 times. The strong emission peak wavelength of lead (Pb) was 405.782 nm.
　（第２評価試験の測定結果）
　図１２の（Ａ）（Ｂ）（Ｃ）は、それぞれ、非対称流路Ｂ、対称流路Ａ、非対称流路Ｃを使用した場合の測定結果を示す。どの測定結果においても、濃度が増加する程、発光強度が増加する傾向を示す。各測定結果から得られた検量線の傾きと検出限界も比較・検討した。検量線の傾きは、図１２の（Ａ）、（Ｂ）、（Ｃ）の順で、約９５（任意単位（ａ．ｕ．））、約１５３（ａ．ｕ．）、約３３３（ａ．ｕ．）を示した。また、検出限界は、図１２（Ａ）、（Ｂ）、（Ｃ）の順で、０．８８ｍｇ／Ｌ、０．２１ｍｇ／Ｌ、０．０２ｍｇ／Ｌを示した。ここで、図１２（Ｂ）の検出限界は、図１２（Ａ）の値により約４倍改善し、図１２（Ｃ）の検出限界は、図１２（Ｂ）の値により約１０倍改善したといえる。 (Measurement results of the second evaluation test)
(A), (B), and (C) of FIG. 12 show the measurement results when using the asymmetric channel B, the symmetric channel A, and the asymmetric channel C, respectively. In any measurement result, the emission intensity tends to increase as the concentration increases. The slope and detection limit of the calibration curve obtained from each measurement result were also compared and examined. The slopes of the calibration curves are about 95 (arbitrary unit (au)), about 153 (au), and about 333 (a) in the order of (A), (B), and (C) in FIG. .U.). The detection limits were 0.88 mg / L, 0.21 mg / L, and 0.02 mg / L in the order of FIGS. 12 (A), (B), and (C). Here, the detection limit of FIG. 12 (B) is improved about 4 times by the value of FIG. 12 (A), and the detection limit of FIG. 12 (C) is improved about 10 times by the value of FIG. 12 (B). It can be said.
　（第２評価試験の考察）
　このように、正極側１０４ｂより負極側１０４ａを長くした非対称流路Ｃを用いた場合に、感度が最も高く、検出限界が低い傾向が示された。これにより、非対称流路Ｃでは極めて高い界面濃縮が生じていると考えられる。 (Consideration of second evaluation test)
Thus, when the asymmetric flow path C in which the negative electrode side 104a is longer than the positive electrode side 104b is used, the sensitivity is highest and the detection limit tends to be low. Thereby, it is considered that extremely high interface concentration occurs in the asymmetric channel C.
　なお、第２評価試験では、測定元素Ｍとして第２グループに属する鉛（Ｐｂ）を用いて、非対称流路Ｃで良好な発光特性を得た。しかしながら、本発明でのＬＥＰ型発光現象は、上述のように、測定元素Ｍの種類に応じて、界面濃縮やプラズマへの導入過程が変化し得る。従って、測定物を別の元素（例えば、上記第１グループに属する元素）に選択した場合は、非対称流路Ａの方が良い場合もあることに留意されたい。これは、長めの拡大流路１０７ａを正極１０４ｂ側に配置した構成の方が、当該流路１０７ａ内で界面濃縮ひいては発光特性が促進される場合があるからである。 In the second evaluation test, good light emission characteristics were obtained in the asymmetric channel C using lead (Pb) belonging to the second group as the measurement element M. However, in the LEP type light emission phenomenon in the present invention, as described above, the interface concentration and the introduction process into the plasma can be changed according to the type of the measurement element M. Therefore, it should be noted that the asymmetric flow path A may be better when the measurement object is selected as another element (for example, an element belonging to the first group). This is because in the configuration in which the longer enlarged flow path 107a is arranged on the positive electrode 104b side, interface concentration and thus light emission characteristics may be promoted in the flow path 107a.
　また、上記実施例では狭小部１０３内の喉部１０８両側において界面濃縮効果に差を生みだすための手段として喉部１０８を基点とした非対称構造を用いたが、本発明はこれに限定されず、以下の実施例も考えられる。 In the above embodiment, the asymmetric structure based on the throat 108 is used as a means for producing a difference in the interface concentration effect on both sides of the throat 108 in the narrow portion 103, but the present invention is not limited to this. The following examples are also conceivable.
　図１３に、別例（実施例３）のプラズマ発生装置１の概略図を示す。図１３に示すプラズマ発生装置１では、圧力調整機構１１０がさらに設けられている点と、狭小部１０３内の喉部１０８はその流路長さＬの中央に形成され、さらにこの喉部１０８両側に接続された拡大流路１０７（つまり、１０７ａ，１０７ｂ）が喉部１０８を基点に対称に形成されている点とを除き、基本的な特徴・構造は、図１に示すプラズマ発生装置１と同様である。 FIG. 13 shows a schematic view of another example (Example 3) of the plasma generator 1. In the plasma generator 1 shown in FIG. 13, the pressure adjusting mechanism 110 is further provided, and the throat portion 108 in the narrow portion 103 is formed at the center of the flow path length L. The basic features and structure are the same as those of the plasma generator 1 shown in FIG. 1 except that the enlarged flow path 107 (that is, 107a and 107b) connected to the throat 108 is formed symmetrically with respect to the base point. It is the same.
　この圧力調整機構１１０は、例えば、図１３に示すように、拡大流路１０７ａ，１０７ｂの一方（例えば、１０７ｂ）に接続された調整管１１１と調整容器１１２とを少なくとも有する。なお、この調整容器１１２は、内部に導電性液体１０５が流入すると容易に変形し、流出すると変形前の状態に戻る可撓性・弾力性を有する材料で構成されていることが好ましい。これによって、調整容器１１２内部や付近の圧力は、喉部１０８での導電性液体１０５の圧力Ｐ０より低い圧力Ｐ１に設定可能となる。 For example, as shown in FIG. 13, the pressure adjustment mechanism 110 includes at least an adjustment pipe 111 and an adjustment container 112 connected to one of the enlarged flow paths 107 a and 107 b (for example, 107 b). The adjustment container 112 is preferably made of a material having flexibility and elasticity that easily deforms when the conductive liquid 105 flows into the inside and returns to the state before deformation when the conductive liquid 105 flows out. As a result, the pressure inside or near the adjustment container 112 can be set to a pressure P 1 lower than the pressure P 0 of the conductive liquid 105 at the throat 108.
　また、調整容器１１２が上記のような材料で構成されていなくとも、調整容器１１２内の一部に圧縮可能な気体（空気）を収容させるようにしてもよい。このようにすれば、プラズマ１０６発生時に高圧の導電性液体１０５によって上記気体が圧縮され、調整容器１１２の内部又は付近の圧力がプラズマ１０６発生位置での圧力Ｐ０より低い圧力Ｐ１に設定される。 Further, even if the adjustment container 112 is not made of the material as described above, a compressible gas (air) may be accommodated in a part of the adjustment container 112. In this way, the gas is compressed by the high-pressure conductive liquid 105 when the plasma 106 is generated, and the pressure in or near the adjustment vessel 112 is set to a pressure P 1 lower than the pressure P 0 at the plasma 106 generation position. The
　電圧印加により狭小部１０３内の喉部１０８に発生する気泡は、喉部１０８に接続された通電経路（拡大流路１０７，１０７、運搬流路１０１，１０１、溶液リザーバ１０２，１０２）内の導電性液体１０５を電極１０４ａ，１０４ｂの入った溶液リザーバ１０２，１０２に向けて溶液界面を均等な圧力Ｐ０で押しやりながら蒸発範囲を広げようとする。実施例３では、狭小部１０３はその喉部１０８が中央に配置され、その拡大流路１０７ａ，１０７ｂが上述のように対称であるため、双方いずれの拡大流路１０７ａ，１０７ｂでも蒸発速度は同様になろうとする。 Bubbles generated in the throat 108 in the narrow portion 103 due to voltage application are conducted in the energization path ( enlarged flow channels 107, 107, transport channels 101, 101, solution reservoirs 102, 102) connected to the throat 108. and Grow evaporated range while forces the solution interface at a uniform pressure P 0 toward a solution reservoir 102, 102 containing the sex liquid 105 electrodes 104a, of 104b. In the third embodiment, the narrow portion 103 has the throat portion 108 disposed in the center and the enlarged flow passages 107a and 107b are symmetrical as described above. Therefore, the evaporation speed is the same in both of the enlarged flow passages 107a and 107b. Try to become.
　しかしながら、上述のような圧力調整機構１１０を一方の電極（図示では１０４ｂ）側の拡大流路（図示では１０７ｂ）又は運搬流路１０１のみに設け、蒸発時に所定の圧力Ｐ１に設定されることで、拡大流路１０７ｂ近傍の導電性液体１０５（の質量の一部）が圧力調整機構１１０内に強制的に吸引されることになり、強制吸引された一方の電極１０４ｂ側の拡大流路１０７ｂに残された導電性液体１０５の移動速度は、喉部１０８を越えた他方の電極１０４ａ側に収容された導電性液体１０５の移動速度よりも早くなる。従って、喉部１０８を基点とした両側において、導電性液体１０５の移動抵抗に差が生じ、一側の電極１０４ａ側の導電性液体１０５でプラズマ１０６をより長時間発生させることが可能となる。これにより、電極１０４ａ側での界面濃縮効果を高めてその付近に存在する測定元素Ｍの感度を向上させることができる。 However, it provided only in or transport channel 101 (107 b in the figure) larger passage side (104b in the illustrated) one electrode of pressure adjustment mechanism 110 as described above, it is set to a predetermined pressure P 1 at the time of evaporation Thus, the conductive liquid 105 (part of its mass) in the vicinity of the enlarged flow path 107b is forcibly sucked into the pressure adjustment mechanism 110, and the enlarged flow path 107b on the side of the one electrode 104b that has been forcibly sucked. The moving speed of the conductive liquid 105 remaining in the first electrode is faster than the moving speed of the conductive liquid 105 accommodated on the other electrode 104a side beyond the throat portion. Therefore, there is a difference in the movement resistance of the conductive liquid 105 on both sides starting from the throat 108, and the plasma 106 can be generated for a longer time by the conductive liquid 105 on the one electrode 104a side. Thereby, the interface concentration effect on the electrode 104a side can be enhanced and the sensitivity of the measurement element M existing in the vicinity thereof can be improved.
　なお、測定対象が遷移金属である場合は、マイナス電極側１０４ａにプラズマ１０６が発生しやすい傾向があるので、圧力調整機構１１０をプラス電極１０４ｂ側の通電経路に接続することが好ましい。 When the measurement object is a transition metal, the plasma 106 tends to be generated on the negative electrode side 104a. Therefore, it is preferable to connect the pressure adjustment mechanism 110 to the energization path on the positive electrode 104b side.
　図１４に、別例（実施例４）のプラズマ発生装置１の概略を説明した図を示す。図１４に示すプラズマ発生装置１の狭小部１０３には、拡大流路１０７ａ，１０７ｂに加え出口流路１２０及び出口ポート１２１が接続されている。また、電極１０４ａ，１０４ｂが挿入された溶液リザーバ１０２，１０２のいずれにも供給管１３０（詳しくは１３０ａ，１３０ｂ）が接続されている。供給管１３０には導電性液体１０５を供給する供給ポート１３１が接続されている。なお、図１４に示す例では、１つの供給ポート１３１から両方の供給管１３０ａ，１３０ｂが分岐していくように接続されているが、必ずしもこれに限定されず、供給管１３０ａ，１３０ｂの各々に対して別個の供給ポート１３１を用意してもよい。 FIG. 14 shows a schematic diagram of another example (Example 4) of the plasma generator 1. In addition to the enlarged channels 107a and 107b, an outlet channel 120 and an outlet port 121 are connected to the narrow portion 103 of the plasma generator 1 shown in FIG. A supply pipe 130 (specifically, 130a and 130b) is connected to both of the solution reservoirs 102 and 102 into which the electrodes 104a and 104b are inserted. A supply port 131 for supplying the conductive liquid 105 is connected to the supply pipe 130. In the example shown in FIG. 14, both supply pipes 130a and 130b are branched from one supply port 131. However, the present invention is not limited to this, and the supply pipes 130a and 130b are connected to each other. On the other hand, a separate supply port 131 may be prepared.
　実施例４では、プラズマ１０６が発生する喉部１０８は、電極１０４ａ，１０４ｂが挿入された溶液リザーバ１０２，１０２から導電性液体１０５が流入する２つの拡大流路１０７ａ，１０７ｂと、この導電性液体１０５が出口ポート１２１に向かって流出する出口流路１２０と、に接続されている（この出口ポート１２１が付加された流路を、以下、Ｔ型流路とも呼ぶ）。 In the fourth embodiment, the throat 108 where the plasma 106 is generated includes two enlarged flow paths 107a and 107b into which the conductive liquid 105 flows from the solution reservoirs 102 and 102 into which the electrodes 104a and 104b are inserted, and the conductive liquid. 105 is connected to an outlet channel 120 that flows out toward the outlet port 121 (hereinafter, the channel to which the outlet port 121 is added is also referred to as a T-type channel).
　狭小部１０３の喉部１０８付近で生じた気泡は、狭小部１０３に接続された２つの拡大流路１０７ａ，１０７ｂと、出口流路１２０と、に向かって圧力Ｐ０で導電性液体１０５を押しやりながら広がっていこうとする。しかしながら、出口流路１２０は図示のように喉部１０８両側の拡大流路１０７ａ，１０７ｂより、大きな流路断面積を有しているため、出口流路１２０での液体１０５の移動抵抗は小さくなる一方、両電極１０４ａ，１０４ｂ側の拡大流路１０７ａ，１０７ｂでの液体１０５の移動抵抗は大きくなるため、これらの拡大流路１０７ａ，１０７ｂ内でのプラズマ１０６の発生はより長時間となる。 Bubbles generated in the vicinity of the throat portion 108 of the narrow portion 103 push the conductive liquid 105 at a pressure P 0 toward the two enlarged flow passages 107 a and 107 b connected to the narrow portion 103 and the outlet flow passage 120. Try to spread while doing. However, since the outlet channel 120 has a larger channel cross-sectional area than the enlarged channels 107a and 107b on both sides of the throat portion 108 as shown in the figure, the movement resistance of the liquid 105 in the outlet channel 120 is reduced. On the other hand, since the movement resistance of the liquid 105 in the enlarged flow paths 107a and 107b on the both electrodes 104a and 104b side is increased, the generation of the plasma 106 in these enlarged flow paths 107a and 107b takes a longer time.
　なお、電極１０４ａ，１０４ｂに電圧を印加した際、この電極１０４ａ，１０４ｂが挿入された夫々の溶液リザーバ１０２，１０２内の導電性液体１０５から運搬流路１０１，１０１及び狭小部１０３内の導電性液体１０５へ向けて電気が流れやすいことが望まれる。この状況を実現するために、供給管１３０は、運搬流路１０１，１０１や拡大流路１０７ａ，１０７ｂに比べ著しく細く又は長くなるように構成することが好ましい。より好ましくは、供給管１３０は、運搬流路１０１，１０１や拡大流路１０７ａ，１０７ｂに比べ、１０分の１以下の流路断面積を有するか、或いは、１０倍以上の長さを有するように構成される。つまり、導電性液体１０５内の電気抵抗は導電経路の長さに比例しかつ流路断面積に反比例するため、電圧が電極１０４ａ，１０４ｂに印加されたとしても供給管１３０が形成し得る通電経路は電気抵抗が著しく大きくなり、この供給管１３０を経由した経路には電気を流さず狭小部１０３に向かう経路にのみ電気を流すことが可能となる。 In addition, when a voltage is applied to the electrodes 104a and 104b, the conductive liquid 105 in the respective solution reservoirs 102 and 102 into which the electrodes 104a and 104b are inserted from the conductive flow channels 101 and 101 and the conductivity in the narrow portion 103. It is desirable that electricity easily flows toward the liquid 105. In order to realize this situation, the supply pipe 130 is preferably configured to be significantly thinner or longer than the transport channels 101 and 101 and the enlarged channels 107a and 107b. More preferably, the supply pipe 130 has a channel cross-sectional area of 1/10 or less, or 10 times or more the length of the transport channels 101 and 101 and the enlarged channels 107a and 107b. Configured. That is, since the electrical resistance in the conductive liquid 105 is proportional to the length of the conductive path and inversely proportional to the cross-sectional area of the flow path, the current supply path that can be formed by the supply pipe 130 even when a voltage is applied to the electrodes 104a and 104b. Since the electric resistance is remarkably increased, it is possible to flow electricity only to the path toward the narrow portion 103 without flowing electricity through the path via the supply pipe 130.
　また、上述の出口流路１２０、供給管１３０等を備えた実施例４（後述の実施例５も同様）においては、電極１０４ａ，１０４ｂに印加する電圧を交流電圧にしてもよい。電圧を交流にすれば、次のような測定上非常に大きな複数のメリットを享受できることが期待できるからである。 In Example 4 (including Example 5 described later) provided with the outlet channel 120 and the supply pipe 130 described above, the voltage applied to the electrodes 104a and 104b may be an AC voltage. This is because if the voltage is changed to an alternating current, it can be expected that a plurality of merits in the following measurement can be enjoyed.
　先ず、第１のメリットとして、負極１０４ａと正極１０４ｂで異なっている現象（発光、電極上での気泡の発生など）が平均化されたり、一方向の電流による液体１０５やイオンの流れ、電気化学反応による電極１０４ａ，１０４ｂ上へメッキ・分解・生成反応等の測定上望ましくない現象が打ち消されたりするため、より安定した測定が行える。 First, as a first merit, different phenomena between the negative electrode 104a and the positive electrode 104b (emission, generation of bubbles on the electrode, etc.) are averaged, the flow of the liquid 105 or ions due to a unidirectional current, electrochemical Undesirable phenomena such as plating / decomposition / generation reaction on the electrodes 104a and 104b due to the reaction are canceled out, so that more stable measurement can be performed.
　また、第２のメリットとして、交流電圧であれば、液体１０５と電極１０４ａ，１０４ｂとの間に誘電体（つまり、直流電圧に対しては電気を通さない絶縁体としてふるまう物質）を挟んでも、容量結合的に電圧を印加できる。このため、電極１０４ａ，１０４ｂを液体１０５に接触させる必要がなく、装置１の構造を簡単にでき、液漏れを防ぐことができ、また不純物の混入を防ぐことができ、より高純度に元素の測定が可能となる。 As a second merit, even if an AC voltage is used, a dielectric (that is, a substance that behaves as an insulator that does not conduct electricity with respect to a DC voltage) is sandwiched between the liquid 105 and the electrodes 104a and 104b. A voltage can be applied capacitively. For this reason, it is not necessary to bring the electrodes 104a and 104b into contact with the liquid 105, the structure of the apparatus 1 can be simplified, liquid leakage can be prevented, and contamination of impurities can be prevented. Measurement is possible.
　図１５に、別例（実施例５）のプラズマ発生装置１の概略図を示す。図１５に示すプラズマ発生装置１は、出口流路１２０に圧力調整機構１１０が設けられている点以外は、上記実施例４と略同様である。なお、実施例５の出口流路１２０は、上記実施例４の場合のようにその流路断面積を喉部１０８両側の拡大流路１０７ａ，１０７ｂよりも大きくする必要は無い。しかしながら、出口流路１２０には、実施例４で説明したような圧力調整機構１１０が設けられている。 FIG. 15 shows a schematic view of another example (Example 5) of the plasma generator 1. The plasma generator 1 shown in FIG. 15 is substantially the same as the fourth embodiment except that the pressure adjusting mechanism 110 is provided in the outlet channel 120. The outlet channel 120 of Example 5 does not need to have a larger channel cross-sectional area than the enlarged channels 107a and 107b on both sides of the throat portion 108 as in the case of Example 4. However, the outlet channel 120 is provided with the pressure adjusting mechanism 110 as described in the fourth embodiment.
　この圧力調整機構１１０は、例えば、図１５に示すように、出口流路１２０に接続された調整管１１１と調整容器１１２とを少なくとも有する。なお、本実施例の調整容器１１２も、先の実施例の場合と同様に、高圧の導電性液体１０５が調整容器内１１２に流入・流出した場合に変形するか或いは圧縮可能な気体を収容することで、調整容器１１２の内部又は周辺がプラズマ１０６発生箇所での圧力Ｐ０より低い圧力Ｐ１に設定可能となる。 For example, as shown in FIG. 15, the pressure adjustment mechanism 110 includes at least an adjustment pipe 111 and an adjustment container 112 connected to the outlet channel 120. The adjustment container 112 of the present embodiment also contains a gas that is deformed or compressible when the high-pressure conductive liquid 105 flows into and out of the adjustment container 112 as in the previous embodiment. As a result, the inside or the periphery of the adjustment vessel 112 can be set to a pressure P 1 lower than the pressure P 0 at the location where the plasma 106 is generated.
　圧力調整機構１１０は、上述のように設け、蒸発時に所定の圧力Ｐ１に設定されることで、出口流路１２０近傍の導電性液体１０５（の質量の一部）が圧力調整機構１１０内に強制的に吸引されることになる。この強制的吸引によって出口流路１２０内に残された導電性液体１０５の移動速度を調整（つまり増加）することができ、喉部１０８にて発生した蒸発が出口ポート１２１に向かって強制的に進展する一方、両電極１０４ａ，１０４ｂ側の拡大流路１０７ａ，１０７ｂでは蒸発の進展は鈍り、ひいては、これらの拡大流路１０７ａ，１０７ｂ内のプラズマ１０６をより長時間発生させることができる。 Pressure adjusting mechanism 110 is provided as described above, it is set to a predetermined pressure P 1 at the time of evaporation, the outlet channel 120 (a portion of the mass) conductive liquid 105 in the vicinity of the pressure adjusting mechanism 110 It will be forcibly sucked. By this forced suction, the moving speed of the conductive liquid 105 remaining in the outlet channel 120 can be adjusted (that is, increased), and evaporation generated in the throat 108 is forced toward the outlet port 121. On the other hand, the progress of evaporation is slowed down in the enlarged flow paths 107a and 107b on the both electrodes 104a and 104b side, and as a result, the plasma 106 in these enlarged flow paths 107a and 107b can be generated for a longer time.
　（第３評価試験：Ｔ型流路の作製及び評価）
　実施例６では、実施例４に示した実施形態に近いＴ型流路を実際に作製し、実証試験を行った。図１６（Ａ）は、Ｔ型流路の流路パターンを示し、図１６（Ｂ）は、その一部（つまり狭小部付近の流路）を拡大した図を示す。Ｔ型流路は、第１層（石英製）２０１と、この第１層２０１に積層された第２層（ＰＤＭＳ製）２０２とから区画されている（図１７を参照）。 (Third evaluation test: production and evaluation of a T-shaped channel)
In Example 6, a T-shaped channel close to the embodiment shown in Example 4 was actually produced, and a verification test was performed. FIG. 16A shows a flow path pattern of a T-shaped flow path, and FIG. 16B shows an enlarged view of a part thereof (that is, a flow path near a narrow portion). The T-type channel is partitioned from a first layer (made of quartz) 201 and a second layer (made of PDMS) 202 laminated on the first layer 201 (see FIG. 17).
　なお、第１層２０１はエッチングすることにより作製可能である。電極１０４ａ，１０４ｂは白金及びクロム（Ｐｔ／Ｃｒ）を溶液リザーバ１０２の底面に相当する第１層２０１の表面部分にスパッタリングすることにより作製可能である。なお、溶液リザーバ１０２の底面部分に電極１０４，１０４を第２層２０２はＳＵ－８モールディング方法を用いて作製可能である。 Note that the first layer 201 can be manufactured by etching. The electrodes 104 a and 104 b can be produced by sputtering platinum and chromium (Pt / Cr) on the surface portion of the first layer 201 corresponding to the bottom surface of the solution reservoir 102. The electrodes 104 and 104 and the second layer 202 can be formed on the bottom surface portion of the solution reservoir 102 by using the SU-8 molding method.
　以上のように作製された流路の高さ（深さ）は１００μｍであり、流路の供給ポート１３１から出口ポート１２１までに亘って一定である。狭小部１０３の長さは５００μｍであり、溶液リザーバ１０２，１０２の幅と長さは、それぞれ１．５ｍｍと３ｍｍである。また、溶液リザーバ１０２，１０２内に埋め込まれた電極１０４，１０４の厚さは０．３μｍである。 The height (depth) of the flow path produced as described above is 100 μm, and is constant from the supply port 131 to the outlet port 121 of the flow path. The length of the narrow portion 103 is 500 μm, and the width and length of the solution reservoirs 102 and 102 are 1.5 mm and 3 mm, respectively. The thickness of the electrodes 104 and 104 embedded in the solution reservoirs 102 and 102 is 0.3 μm.
　なお、従来の電極構造（例えば、図３に示したワイヤ状の電極１０４）では、ワイヤ状の電極１０４を導電性液体１０５が流通する図示しない管内に挿入する構成であっために、導電性液体１０５の圧力が逃げやすかった。これに対して、本実施例では、電極１０４，１０４が溶液リザーバ１０２の底面に埋め込まれており、このリザーバ１０２，１０２を導電性液体１０５が通過する際に障害となりにくい。従って、導電性液体１０５を所望の圧力に維持したままで狭小部１０３に流入させることができる。 In the conventional electrode structure (for example, the wire-like electrode 104 shown in FIG. 3), the wire-like electrode 104 is inserted into a tube (not shown) through which the conductive liquid 105 circulates. 105 pressure was easy to escape. On the other hand, in the present embodiment, the electrodes 104 and 104 are embedded in the bottom surface of the solution reservoir 102, and it is difficult for the conductive liquid 105 to pass through the reservoirs 102 and 102. Therefore, the conductive liquid 105 can flow into the narrow portion 103 while maintaining a desired pressure.
　（第３評価試験のための装置）
　上記チップは、図１７に示す発光分光分析装置によって発光特性が評価された。ここで、図１７中の各符号を説明する。図１７に示す装置は、その光学系として、パーソナルコンピュータ４０１，４０２、ＣＣＤ検出器４０３、スペクトロメータ４０４、光ファイバー２０４、高速カメラ４１５を備える。第１層２０１と第２層２０２とを備えたＴ型チップはステージ４０５上で固定される。パーソナルコンピュータ４０１，４０２と、白金電極４０７とは、直流電源４０７に接続される。サンプル溶液１０５はシリンジ４０８内に満たされており、ポンプ４０９によって、フッ素樹脂チューブ４１０へ押し出され、Ｔ型流路を通過する。その後、サンプル溶液１０５は、フッ素樹脂チューブ４１１を通過した後、廃液４１３として回収容器４１２に収集される。 (Equipment for third evaluation test)
The chip was evaluated for light emission characteristics by an emission spectroscopic analyzer shown in FIG. Here, each reference numeral in FIG. 17 will be described. The apparatus shown in FIG. 17 includes personal computers 401 and 402, a CCD detector 403, a spectrometer 404, an optical fiber 204, and a high-speed camera 415 as its optical system. The T-type chip including the first layer 201 and the second layer 202 is fixed on the stage 405. The personal computers 401 and 402 and the platinum electrode 407 are connected to a DC power source 407. The sample solution 105 is filled in the syringe 408 and is pushed out by the pump 409 to the fluororesin tube 410 and passes through the T-shaped channel. Thereafter, the sample solution 105 passes through the fluororesin tube 411 and is collected in the collection container 412 as a waste liquid 413.
　（第３評価試験のための測定条件）
　測定に供した試料は、鉛（Ｐｂ）、ナトリウム（Ｎａ）、水素（Ｈ　波長６５６ｎｍ）、又は水素（Ｈ　波長４８６ｎｍ）の元素を用い、０．５ｍｇ／Ｌの濃度に調整された溶液を用いた。溶媒として０．１Ｍの硝酸（ＨＮＯ３）を用いた。印加電圧は６００Ｖのパルス状電圧とし、パルスのオン時間を０．５ｍｓ、オフ時間を９．５ｍｓとした。溶液供給用の流量は５μＬ／ｍｉｎに設定した。なお、各元素の発光強度の測定回数Ｎを１０回とし、その平均値を測定結果として用いた。 (Measurement conditions for the third evaluation test)
For the sample used for the measurement, a solution adjusted to a concentration of 0.5 mg / L using an element of lead (Pb), sodium (Na), hydrogen (H wavelength 656 nm), or hydrogen (H wavelength 486 nm) is used. It was. 0.1M nitric acid (HNO 3 ) was used as the solvent. The applied voltage was a pulse voltage of 600 V, the pulse on time was 0.5 ms, and the off time was 9.5 ms. The flow rate for supplying the solution was set to 5 μL / min. In addition, the measurement frequency N of the light emission intensity of each element was 10 times, and the average value was used as the measurement result.
　（プラズマ及び気泡の観察）
　図１８（Ａ）～（Ｄ）は、実施例６の狭小部１０３で観測されたプラズマ１０６及び気泡の挙動を示したものである。図１８（Ａ）及び（Ｂ）は、ある条件のパルスのオン時間での状態及びオフ時間での状態を示し、図１８（Ｃ）及び（Ｄ）は、別の条件のパルスでのオン時間での状態及びオフ時間での状態を示す。図１８（Ａ）及び（Ｂ）では、オン時間からオフ時間に切り替わっても、気液界面（図中、ＢＤ）はほとんど移動していないことが観測された（図１８（Ｂ）中の矢印を参照）。これに対し、図１８（Ｃ）及び（Ｄ）では、オン時間からオフ時間に切り替わると、気液界面ＢＤは、出口流路１２０の内部まで入りこんでしまっており、その移動量が大きいことが観察された。 (Observation of plasma and bubbles)
18A to 18D show the behavior of the plasma 106 and bubbles observed in the narrow portion 103 of the sixth embodiment. FIGS. 18A and 18B show a state of a pulse having a certain condition at an on time and a state at an off time, and FIGS. 18C and 18D show an on time of a pulse having another condition. The state at and the state at off time are shown. 18 (A) and 18 (B), it was observed that the gas-liquid interface (BD in the figure) hardly moved even when the on time was switched to the off time (arrow in FIG. 18 (B)). See). On the other hand, in FIGS. 18C and 18D, when the on-time is switched to the off-time, the gas-liquid interface BD has penetrated into the outlet channel 120, and the movement amount is large. Observed.
　これにより、パルス電圧を印加する条件が元素の界面濃縮及び発光特性に影響することが分かった。特に、図１８（Ａ）及び（Ｂ）に示す好適な状態を作り出すには、狭小部１０３での水分の蒸発速度と狭小部１０３への溶液１０５の供給速度とが釣り合うように、パルス電圧を印加する必要があることが分かった。 Thus, it was found that the condition for applying the pulse voltage affects the interface concentration of elements and the light emission characteristics. In particular, in order to create a preferable state shown in FIGS. 18A and 18B, the pulse voltage is set so that the water evaporation rate in the narrow portion 103 and the supply speed of the solution 105 to the narrow portion 103 are balanced. It was found that it was necessary to apply.
　（第３評価試験の測定結果）
　図１９（Ａ）は、実施例６の流路を用いて測定された発光強度を示す。横軸はパルス数を積算した数であり、縦軸は積算した発光強度（任意単位）を示す。図１９では、積算パルス数が少ないうちは、積算パルス数の増加に伴って発光強度の増加を観察することができるが、積算パルスが有る程度大きくなると、積算パルス数が増加しても発光強度の増加は見られない。 (Measurement results of the third evaluation test)
FIG. 19A shows the light emission intensity measured using the flow channel of Example 6. The horizontal axis represents the number obtained by integrating the number of pulses, and the vertical axis represents the integrated emission intensity (arbitrary unit). In FIG. 19, while the number of integrated pulses is small, an increase in emission intensity can be observed as the number of integrated pulses increases. However, if the number of integrated pulses increases, the emission intensity increases even if the number of integrated pulses increases. There is no increase.
　図１９（Ｂ）は、図１９（Ａ）の各データを図１９（Ａ）の水素（Ｈ　波長６５６ｎｍ）のデータで除した結果（規格化発光強度とも呼ぶ）を示すグラフである。この図１９（Ｂ）では、ナトリウム（Ｎａ）や鉛（Ｐｂ）を用いた場合は、積算パルス数が０～約５０の範囲で規格化発光強度が増加し、５０付近でピーク（約１．５倍）を示す。なお、図示の実線は、パルス数が少ない範囲でのナトリウム（Ｎａ）や鉛（Ｐｂ）の測定結果の傾向を示した線である。積算パルス数が５０を超えていくと徐々に減少し、２００を超えると規格化発光強度は一定値（約１）となることが観察される。この結果より、実施例６の装置は上記元素について約１．５倍の界面濃縮を実現できたといえる。 FIG. 19B is a graph showing the result (also referred to as normalized emission intensity) obtained by dividing each data of FIG. 19A by the data of hydrogen (H wavelength 656 nm) of FIG. 19A. In FIG. 19 (B), when sodium (Na) or lead (Pb) is used, the normalized emission intensity increases in the range of the integrated pulse number from 0 to about 50, and the peak (about 1. 5 times). The solid line shown in the figure is a line showing the tendency of the measurement results of sodium (Na) and lead (Pb) in a range where the number of pulses is small. It is observed that when the cumulative number of pulses exceeds 50, it gradually decreases, and when it exceeds 200, the normalized emission intensity becomes a constant value (about 1). From this result, it can be said that the apparatus of Example 6 was able to realize the interface concentration about 1.5 times with respect to the above elements.
　さらに高い濃縮効果を得るには、気液界面ＢＤをより長時間存続させることだけでなく、後述するように、界面ＢＤでの振動の発生を極力抑えることが有効であると考えられる。ここで、実施例６の狭小部１０３は柔らかいＰＤＭＳで作られているため、界面ＢＤでの振動が起こり、濃縮率が余り改善されなかったと推察される。 In order to obtain a higher concentration effect, it is considered effective not only to keep the gas-liquid interface BD for a longer period of time, but also to suppress the generation of vibration at the interface BD as much as possible, as will be described later. Here, since the narrow portion 103 of Example 6 is made of soft PDMS, it is assumed that vibration at the interface BD occurred and the concentration rate was not improved so much.
　図２０（Ａ）は、ＰＤＭＳ製の狭小部１０３を用い、界面ＢＤでの振動の影響を考慮して計算したシミュレーション結果である。図２０（Ａ）中の上側の３本の線は積算パルス数と界面濃縮率（ＣｂをＣｏで除した値）との関係を示し、下側の３本の線は積算パルス数とプラズマへの導入率との関係を示す。なお、プラズマ導入係数ＫをＫ＝０．０１、Ｋ＝０．１、Ｋ＝０．３の３つの場合を仮定したため、それぞれ３本ずつ線が描かれている。 FIG. 20A shows a simulation result calculated using the narrow portion 103 made of PDMS in consideration of the influence of vibration at the interface BD. Figure 20 three lines of upper side of (A) shows the relationship between the cumulative pulse number and the interfacial condensation rate (a value of C b divided by C o), three lines of lower and accumulated number of pulses The relationship with the introduction rate into plasma is shown. Since three cases where the plasma introduction coefficient K is K = 0.01, K = 0.1, and K = 0.3 are assumed, three lines are drawn respectively.
　図２０（Ｂ）は、石英製の狭小部１０３を用い、界面振動の影響が無いと仮定して計算したシミュレーション結果である。プラズマ導入係数ＫをＫ＝０．１とＫ＝０．０１の２つの場合を仮定したため、積算パルス数と界面濃縮率との関係を示す線と、積算パルス数とプラズマへの導入率との関係を示す線とが、それぞれ２本ずつ描かれている。 FIG. 20B shows a simulation result calculated using a narrow portion 103 made of quartz and assuming that there is no influence of interface vibration. Since the plasma introduction coefficient K is assumed to be two cases of K = 0.1 and K = 0.01, the line indicating the relationship between the integrated pulse number and the interface concentration rate, and the integrated pulse number and the introduction rate into the plasma Two lines each showing the relationship are drawn.
　（シミュレーション解析）
　次に、上記シミュレーション結果は、次のような数値モデルにより取得した。図１７の装置で取得した画像（図１８を参照）より、パルス電圧の１周期で気液界面ＢＤは２００μｍ程度振動していることが観測された。従って、気液界面ＢＤから４００μｍ程度の距離にある液体１０５は、振動により撹拌されると考えられる。実施例６では流路断面積も変化しているが、モデルを単純化するために、界面ＢＤよりおよそ３００μｍの距離迄にある４ｎＬの液体１０５に注目にする。 (Simulation analysis)
Next, the simulation result was obtained by the following numerical model. From the image acquired with the apparatus of FIG. 17 (see FIG. 18), it was observed that the gas-liquid interface BD vibrates about 200 μm in one cycle of the pulse voltage. Therefore, it is considered that the liquid 105 at a distance of about 400 μm from the gas-liquid interface BD is stirred by vibration. In Example 6, the channel cross-sectional area is also changed, but in order to simplify the model, attention is paid to 4 nL of the liquid 105 located at a distance of about 300 μm from the interface BD.
　（数値モデル）
　この液体１０５（注目体積と呼ぶ。）は、上記の撹拌により、１周期ごとに濃度がほぼ均一化されると仮定する。次に、１パルスあたりの注目体積への元素Ｍの出入りを考える。所望量の気泡が狭小部１０３内に維持できている条件では、液体１０５の流量と蒸発量とがバランスしているので、１パルスあたりに、入口側から注目体積に入ってくる液量と、注目体積の出口側から溶媒が蒸発する量とは等しい。これは、流量を単位時間当たりの周期数で割ることにより計算でき、片側の１つの注目体積につき約０．０４ｎＬと計算できる。入口側の液体１０５中の測定物の濃度をＣｏ、注目体積中の測定物の濃度をＣｂ、界面ＢＤでのプラズマ１０６への元素Ｍの導入係数をＫとする。１パルスでは、注目体積の出口側では０．０４ｎＬの溶媒が蒸発し、ＣｂとＫと０．０４ｎＬとを掛け合わせた量の測定物がプラズマ１０６に導入される。また、入口側では０．０４ｎＬの溶媒と、Ｃｏと０．０４ｎＬとを掛け合わせた量の測定物が注目体積に入ってくる。 (Numerical model)
It is assumed that the concentration of the liquid 105 (referred to as the volume of interest) is substantially uniform for each cycle by the above stirring. Next, consider the entry and exit of the element M into the volume of interest per pulse. Under the condition that a desired amount of bubbles can be maintained in the narrow portion 103, the flow rate of the liquid 105 and the evaporation amount are balanced, so the amount of liquid entering the target volume from the inlet side per pulse, The amount of solvent evaporation from the outlet side of the target volume is equal. This can be calculated by dividing the flow rate by the number of periods per unit time and can be calculated to be about 0.04 nL per volume of interest on one side. The concentration of the measurement object in the liquid 105 on the inlet side is C o , the concentration of the measurement object in the target volume is C b , and the introduction coefficient of the element M to the plasma 106 at the interface BD is K. In one pulse, at the exit side of the target volume solvent evaporates the 0.04NL, measurement of the amount obtained by multiplying the C b and K and 0.04NL is introduced into the plasma 106. Further, a solvent 0.04nL at the inlet side, the measurement of the amount obtained by multiplying the C o and 0.04nL come into attention volume.
　以上の仮定に基づき、パルス毎に界面濃縮率の上昇を逐次的に計算できる（図２０（Ａ）を参照）。この図２０（Ａ）によると、Ｋ＝０．１又はＫ＝０．０１の場合に、約５０パルスにて界面濃縮率は初期値の１．５倍になり、図１９（Ｂ）に示した発光強度の結果とよく対応する。なお、上述の計算では、拡散による移動は、振動による撹拌効果よりもはるかに小さいと考えられるので、無視している。 Based on the above assumption, the increase in the interface concentration rate can be calculated sequentially for each pulse (see FIG. 20A). According to FIG. 20 (A), when K = 0.1 or K = 0.01, the interface concentration ratio becomes 1.5 times the initial value at about 50 pulses, as shown in FIG. 19 (B). Corresponds well with the emission intensity results. In the above calculation, the movement due to diffusion is considered to be much smaller than the stirring effect due to vibration, and is ignored.
　また、振動による撹拌が無い場合の濃縮率も、シミュレーションにより見積もることができる（図２０（Ｂ）を参照）。この場合は、振動による拡散は無視できない。拡散係数として水の物性値を用い、１パルス当たりの蒸発速度を考えると、およそ０．００５ｎＬを有した界面ＢＤ付近の領域を注目体積として、上記のシミュレーションと同様の計算を行うことができる（図２０（Ｂ）を参照）。 Also, the concentration rate when there is no stirring by vibration can be estimated by simulation (see FIG. 20B). In this case, diffusion due to vibration cannot be ignored. Considering the evaporation rate per pulse using the physical property value of water as the diffusion coefficient, the same calculation as in the above simulation can be performed with the region near the interface BD having approximately 0.005 nL as the target volume ( (See FIG. 20B).
　この図２０（Ｂ）より、Ｋ＝０．１のときは、約５の積算パルスで、プラズマへの導入率が１００％に到達することが見積もられる。一方、Ｋ＝０．０１のときは、約３０の積算パルスで、プラズマへの導入率が約９０％に到達することが見積もられる。また、界面濃縮率もＫ＝０．１のときは最大で約１０倍となり、Ｋ＝０．０１のときは最大で約１００倍となることが見積もられる。 20B, it is estimated that when K = 0.1, the introduction rate to the plasma reaches 100% with about 5 accumulated pulses. On the other hand, when K = 0.01, it is estimated that the introduction rate into the plasma reaches about 90% with about 30 integrated pulses. Further, it is estimated that the interface concentration rate is about 10 times at the maximum when K = 0.1, and about 100 times at the maximum when K = 0.01.
　以上のように、振動による攪拌がない場合は、攪拌が有る場合に比べて、高いプラズマ導入率が期待でき、特定の元素（例えば、上記グループ２に属する元素）に対する感度が低いという従来のこの種の装置（ＬＥＰ）の弱点をほぼ払しょくできると期待できる。振動の原因はＴ型流路の材料（ＰＤＭＳ）の弾性にあると考えられるため、振動による攪拌を無くす為の手段の一つとして、上記材料を石英等の材料に代替することが考えられる。 As described above, when there is no agitation by vibration, a higher plasma introduction rate can be expected than when agitation is present, and the sensitivity to a specific element (for example, an element belonging to the group 2) is low. It can be expected that the weakness of the seed device (LEP) can be almost eliminated. The cause of the vibration is considered to be the elasticity of the material of the T-shaped flow path (PDMS). Therefore, it is conceivable to substitute the above material with a material such as quartz as one of the means for eliminating the stirring by the vibration.
　本発明のプラズマ発生装置及びこれを備えた発光分光分析装置は、微小流体力学やμＴＡＳ（ｍｉｃｒｏ　ｔｏｔａｌ　ａｎａｌｙｓｉｓ　ｓｙｓｔｅｍｓ）、Ｌａｂ　ｏｎ　ａ　ｃｈｉｐといわれる分野に好適に使用することができる。本発明によれば、特に必要な機能および構造の一部を１つの板状のチップに集積させることができる。 The plasma generator of the present invention and the emission spectroscopic analyzer equipped with the plasma generator can be suitably used in fields called microfluid dynamics, μTAS (micro total analysis systems), and Lab on a chip. According to the present invention, part of particularly necessary functions and structures can be integrated on one plate-like chip.
　本発明のプラズマ発生装置及びこれを備えた発光分光分析装置は、必要な検体（例えば、液体試料中の無機成分（金属など））が微量でよく、携帯性、即時性、保守容易、安価などの特徴を有する。本発明の装置は、種々の無機成分（金属元素など）を同時に複数測定可能である。従って、本発明の応用分野は、土壌検査や水質検査、製造工程の品質管理、食品検査（飲料中のミネラル測定）、産業廃棄物（レアメタル、有害物質）の確認、医療用の血液・尿の検査に適用可能である。このような用途や長所から本発明は産業上の利用性が非常に高い。 The plasma generation apparatus of the present invention and the emission spectroscopic analysis apparatus equipped with the plasma generation apparatus of the present invention may require a small amount of a specimen (for example, an inorganic component (metal, etc.) in a liquid sample), and are portable, instant, easy to maintain, inexpensive, etc. It has the characteristics of. The apparatus of the present invention can measure a plurality of various inorganic components (such as metal elements) simultaneously. Therefore, the application fields of the present invention include soil inspection and water quality inspection, quality control of manufacturing processes, food inspection (measuring minerals in beverages), confirmation of industrial waste (rare metal, toxic substances), medical blood and urine Applicable to inspection. Due to such applications and advantages, the present invention has very high industrial applicability.
　１　　プラズマ発生装置
　２　　発光分光分析装置
　１０１　　運搬流路
　１０２　　溶液リザーバ
　１０３　　狭小部
　１０４　　電極
　１０５　　導電性液体
　１０６　　プラズマ
　１０７　　拡大流路
　１０８　　喉部
　１０９　　拡大流路の端部
　１１０　　圧力調整機構
　１１１　　調整管
　１１２　　調整容器
　１２０　　出口流路
　１２１　　出口ポート
　１３０　　供給管
　１３１　　供給ポート
　２０１　　石英ガラス
　２０２　　チップ
　２０４　　光ファイバー
　３０１　　電源
　３０２　　フォトセンサユニット
　３０３　　スイッチ
　３０４　　分光器
　３０５　　コンピュータ
　ＢＤ　　気液界面
　Ｃｂ　　気液界面付近での元素濃度
　Ｃｏ　　液体の元素濃度
　Ｍ　　測定対象の元素
　Ｗ　　水滴 DESCRIPTION OF SYMBOLS 1 Plasma generator 2 Emission spectroscopy analyzer 101 Conveyance channel 102 Solution reservoir 103 Narrow part 104 Electrode 105 Conductive liquid 106 Plasma 107 Enlarged channel 108 Throat part 109 End part of enlarged channel 110 Pressure adjustment mechanism 111 Adjustment tube 112 Adjustment Container 120 Outlet channel 121 Outlet port 130 Supply pipe 131 Supply port 201 Quartz glass 202 Chip 204 Optical fiber 301 Power supply 302 Photo sensor unit 303 Switch 304 Spectrometer 305 Computer BD Gas-liquid interface C b Element concentration near the gas-liquid interface C o Element concentration of liquid M Element to be measured W Water droplet

Claims (12)

  1. 　導電性液体中でプラズマを発生させるプラズマ発生装置であって、
    　前記導電性液体を運搬しかつ絶縁性材料で形成された運搬流路と、
    　前記運搬流路に接続されかつ該運搬流路の断面積よりも著しく小さい断面積を有する狭小部と、
    　前記狭小部に電界が通過するように該狭小部に電界を印加するための手段と、
    　を備え、かつ、
    　前記狭小部の一部分では、他の部分に比較して前記導電性液体の移動抵抗が大きいことを特徴とするプラズマ発生装置。     A plasma generator for generating plasma in a conductive liquid,
    A transport channel for transporting the conductive liquid and formed of an insulating material;
    A narrow portion connected to the transport channel and having a cross-sectional area significantly smaller than the cross-sectional area of the transport channel;
    Means for applying an electric field to the narrow portion so that the electric field passes through the narrow portion;
    And having
    The plasma generating apparatus according to claim 1, wherein a movement resistance of the conductive liquid is larger in a part of the narrow part than in another part.
  2. 　前記狭小部には、流路断面積が最も小さい喉部と、該喉部の両側に前記運搬流路に接続する拡大流路とが形成され、
    　一側の前記拡大流路では、他側の前記拡大流路に比較して前記導電性液体の移動抵抗が大きいことを特徴とする請求項１記載のプラズマ発生装置。     The narrow portion is formed with a throat portion having the smallest channel cross-sectional area, and enlarged channels connected to the transport channel on both sides of the throat portion,
    2. The plasma generating apparatus according to claim 1, wherein a movement resistance of the conductive liquid is larger in the enlarged flow channel on one side than in the enlarged flow channel on the other side.
  3. 　前記拡大流路が前記喉部を基点として非対称に構成されていることを特徴とする請求項２記載のプラズマ発生装置。 3. The plasma generating apparatus according to claim 2, wherein the enlarged flow path is configured asymmetrically with respect to the throat.
  4. 　前記喉部は前記狭小部の一端よりも他端近くに配設され、
    　前記拡大流路は前記喉部から前記運搬流路に向かって次第に拡大する流路断面積を有し、
    　前記一端側に配設された前記拡大流路の最大流路断面積は前記他端側に配設された前記拡大流路の最大流路断面積よりも大きく、
    　前記一端側に配設された前記拡大流路では、前記他端側に配設された前記拡大流路に比較して前記導電性液体の移動抵抗が大きいことを特徴とする請求項３記載のプラズマ発生装置。     The throat is disposed closer to the other end than one end of the narrow portion;
    The enlarged channel has a channel cross-sectional area that gradually expands from the throat toward the transport channel,
    The maximum channel cross-sectional area of the expanded channel disposed on the one end side is larger than the maximum channel cross-sectional area of the expanded channel disposed on the other end side,
    4. The movement resistance of the conductive liquid is larger in the enlarged flow path arranged on the one end side than in the enlarged flow path arranged on the other end side. Plasma generator.
  5. 　前記一端側に配設された前記拡大流路の前記最大流路断面積は前記喉部での前記流路断面積の１．１～１００倍であり、前記他端側に配設された前記拡大流路の前記最大流路断面積は前記喉部の断面積の１．１～５０倍であることを特徴とする請求項４記載のプラズマ発生装置。 The maximum flow path cross-sectional area of the enlarged flow path disposed on the one end side is 1.1 to 100 times the flow path cross-sectional area at the throat portion, and the flow path cross-sectional area disposed on the other end side is 5. The plasma generator according to claim 4, wherein the maximum flow path cross-sectional area of the enlarged flow path is 1.1 to 50 times the cross-sectional area of the throat.
  6. 　前記狭小部に、前記導電性液体の圧力を局所的に増加又は減少させる圧力調整機構がさらに配設されていることを特徴とする請求項１～５のいずれか１項記載のプラズマ発生装置。 The plasma generating apparatus according to any one of claims 1 to 5, wherein a pressure adjusting mechanism for locally increasing or decreasing the pressure of the conductive liquid is further disposed in the narrow portion.
  7. 　導電性液体中でプラズマを発生させるプラズマ発生装置であって、
    　前記導電性液体を運搬しかつ絶縁性材料で形成された運搬流路と、
    　前記運搬流路に接続されかつ該運搬流路の断面積よりも著しく小さい断面積を有する狭小部と、
    　前記狭小部に電界が通過するように該狭小部に電界を印加するための手段と、
    　を備え、かつ、
    　前記狭小部には出口流路がさらに配設され、
    　前記導電性液体を、前記運搬流路から前記狭小部に流入しかつ前記狭小部を経由して前記出口流路から流出するように案内し、
    　前記出口流路の断面積が前記狭小部の前記断面積よりも大きくするか、或いは前記出口流路に前記導電性液体の圧力を局所的に増加又は減少させる圧力調整機構がさらに配設されることで、前記狭小部の少なくとも一部分において、前記出口流路に比較して前記導電性液体の移動抵抗が大きくなることを特徴とするプラズマ発生装置。     A plasma generator for generating plasma in a conductive liquid,
    A transport channel for transporting the conductive liquid and formed of an insulating material;
    A narrow portion connected to the transport channel and having a cross-sectional area significantly smaller than the cross-sectional area of the transport channel;
    Means for applying an electric field to the narrow portion so that the electric field passes through the narrow portion;
    And having
    An outlet channel is further disposed in the narrow portion,
    Guiding the conductive liquid so as to flow into the narrow portion from the transport channel and out of the outlet channel via the narrow portion;
    A pressure adjusting mechanism for increasing or decreasing the pressure of the conductive liquid locally is provided in the outlet channel, or a sectional area of the outlet channel is made larger than the sectional area of the narrow portion. Thus, in at least a part of the narrow portion, the movement resistance of the conductive liquid is increased as compared with the outlet channel.
  8. 　前記狭小部に電界を印加するための前記手段は、電極が挿入された溶液リザーバと、該溶液リザーバに前記導電性液体を供給する供給管と、を備え、かつ、
    　前記供給管の長さが前記運搬流路の長さの１０倍以上であるか、又は、前記供給管の断面積が、前記運搬流路の断面積の１０分の１以下であることを特徴とする請求項１～７のいずれか１項記載のプラズマ発生装置。     The means for applying an electric field to the narrow portion includes a solution reservoir in which an electrode is inserted, and a supply pipe for supplying the conductive liquid to the solution reservoir, and
    The length of the supply pipe is not less than 10 times the length of the transport flow path, or the cross-sectional area of the supply pipe is 1/10 or less of the cross-sectional area of the transport flow path. The plasma generator according to any one of claims 1 to 7.
  9. 　前記狭小部に電界を印加するために交流電圧が用いられることを特徴とする請求項１～８のいずれか１項記載のプラズマ発生装置。 The plasma generating apparatus according to any one of claims 1 to 8, wherein an alternating voltage is used to apply an electric field to the narrow portion.
  10. 　導電性液体中でプラズマを発生させるプラズマ発生装置であって、
    　前記導電性液体を運搬しかつ絶縁性材料で形成された運搬流路と、
    　前記運搬流路中に配置されかつ該運搬流路の断面積よりも著しく小さい断面積を有する狭小部と、
    　前記狭小部に電界が通過するように該狭小部に電界を印加するための手段と、
    　を備え、かつ、
    　前記手段にはマイナス電極とプラス電極とを含み、
    　前記狭小部には、流路断面積が最も小さい喉部と、前記喉部の一方の開口部に接続されかつ流路長さが互いに異なる拡大流路とが形成され、
    　前記流路長さが大きい前記拡大流路は、前記プラズマを発生させる元素の種類に応じて、前記マイナス電極又は前記プラス電極のいずれかの側に配置されるよう構成したことを特徴とするプラズマ発生装置。     A plasma generator for generating plasma in a conductive liquid,
    A transport channel for transporting the conductive liquid and formed of an insulating material;
    A narrow portion disposed in the transport channel and having a cross-sectional area significantly smaller than the cross-sectional area of the transport channel;
    Means for applying an electric field to the narrow portion so that the electric field passes through the narrow portion;
    And having
    The means includes a negative electrode and a positive electrode,
    The narrow portion is formed with a throat portion having the smallest channel cross-sectional area and an enlarged channel that is connected to one opening of the throat portion and has different channel lengths.
    The expanded channel having a large channel length is configured to be arranged on either the minus electrode or the plus electrode depending on the type of element that generates the plasma. Generator.
  11. 　導電性液体中でプラズマを発生させるプラズマ発生装置であって、
    　前記導電性液体を運搬しかつ絶縁性材料で形成された運搬流路と、
    　前記運搬流路に接続されかつ該運搬流路の断面積よりも著しく小さい断面積を有する狭小部と、
    　前記狭小部に電界が通過するように該狭小部に電界を印加するための電極と、
    　を備え、かつ、
    　前記狭小部には出口流路がさらに配設され、
    　前記導電性液体を、前記運搬流路から前記狭小部に流入しかつ前記狭小部を経由して前記出口流路から流出するように案内し、
    　前記狭小部への前記液体の供給速度と、前記狭小部での前記液体の蒸発速度とが釣り合うように前記電界が印加されていることを特徴とするプラズマ発生装置。     A plasma generator for generating plasma in a conductive liquid,
    A transport channel for transporting the conductive liquid and formed of an insulating material;
    A narrow portion connected to the transport channel and having a cross-sectional area significantly smaller than the cross-sectional area of the transport channel;
    An electrode for applying an electric field to the narrow portion so that the electric field passes through the narrow portion;
    And having
    An outlet channel is further disposed in the narrow portion,
    Guiding the conductive liquid so as to flow into the narrow portion from the transport channel and out of the outlet channel via the narrow portion;
    The plasma generator according to claim 1, wherein the electric field is applied so that a supply speed of the liquid to the narrow portion and an evaporation speed of the liquid in the narrow portion are balanced.
  12. 　請求項１～１１のいずれか１項記載のプラズマ発生装置を備えた発光分光分析装置。 An emission spectroscopic analysis apparatus comprising the plasma generator according to any one of claims 1 to 11.
PCT/JP2012/073585 2011-09-16 2012-09-14 Plasma generation device and emission spectrophotometer WO2013039189A1 (en)

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