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WO1995032007A1 - Melange d'agents sterilisateurs et procede de sterilisation - Google Patents

Melange d'agents sterilisateurs et procede de sterilisation Download PDF

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Publication number
WO1995032007A1
WO1995032007A1 PCT/US1994/005655 US9405655W WO9532007A1 WO 1995032007 A1 WO1995032007 A1 WO 1995032007A1 US 9405655 W US9405655 W US 9405655W WO 9532007 A1 WO9532007 A1 WO 9532007A1
Authority
WO
WIPO (PCT)
Prior art keywords
mixture
sterilant
ethylene oxide
sterilant mixture
mole percent
Prior art date
Application number
PCT/US1994/005655
Other languages
English (en)
Inventor
Vinci Martinez Felix
Richard Edward Fernandez
Original Assignee
E.I. Du Pont De Nemours And Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by E.I. Du Pont De Nemours And Company filed Critical E.I. Du Pont De Nemours And Company
Priority to PCT/US1994/005655 priority Critical patent/WO1995032007A1/fr
Publication of WO1995032007A1 publication Critical patent/WO1995032007A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L2/00—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor
    • A61L2/16—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor using chemical substances
    • A61L2/20—Gaseous substances, e.g. vapours
    • A61L2/206—Ethylene oxide

Definitions

  • This invention relates generally to the field of sterilization and more particularly to sterilization based on the use of ethylene oxide.
  • Sterilization by the application of boiling water or steam to the article to be sterilized has been carried out for many years. More recently there has arisen in certain fields, such as in medicine and in space exploration, the need to employ a different sterilant because certain articles used in these fields cannot withstand the temperatures or the moisture associated with steam sterilization.
  • ethylene oxide One sterilant that has become widely used is ethylene oxide because not only is it an effective sterilant but also its residues volatilize relatively quickly from the article sterilized.
  • ethylene oxide may be used by itself to carry out the sterilization, this is generally not done because ethylene oxide is highly flammable. Instead, ethylene oxide sterilant is generally used in a mixture with a flame retardant. The flame retardant, however, must complement the properties of the ethylene oxide or the beneficial effects of the ethylene oxide will be lost. Over the last two decades the flame retardant of choice for use with ethylene oxide in a sterilant mixture has been dichlorodifluoromethane, known in the industry as CFC-12.
  • the most commonly used sterilant mixture comprises 27.3 mole percent (12 weight percent) ethylene oxide and 72.7 mole percent (88 weight percent) CFC-12. This mixture is commonly referred to in the industry as "12-88".
  • CFC-12 is one of the chlorofluorocarbons believed to cause significant damage to the ozone layer in the upper atmosphere. Accordingly, worldwide reduction and elimination of the use of CFC-12 is now underway. This has created a problem for the use of ethylene oxide as a sterilant.
  • Alternative flame retardants have been proposed, but they are not as effective as CFC-12 in that less ethylene oxide can be mixed with these alternatives before the mixture becomes flammable.
  • the maximum amount of ethylene oxide that may be mixed with either l,l-dichloro-2,2,2-trifluoroethane (HCFC-123) or l-chloro-l,2,2,2-tetrafluoroethane (HCFC-124) before the mixture becomes flammable is 23 mole percent.
  • HFC-125 For pentafluoroethane (HFC-125), the maximum amount of ethylene oxide that can be added to HFC- 125 before the mixture becomes flammable is 19 mole percent, for 1,2,2,2-tetrafluoroethane (HFC- 134a), the maximum amount of ethylene oxide is 12 mole percent, and for 1,1,1,3,3,3-hexafluoropropane (HFC-236fa), the maximum amount of ethylene oxide is 22 mole percent.
  • HCFC-123 and HCFC-124 both contain chlorine and therefore may adversely affect the Earth's atmosphere.
  • ethylene oxide may be used by itself as a sterilant.
  • explosion danger of such use makes it acceptable for only a relatively few applications at locations which have experienced and sophisticated handlers available at all times.
  • One flame retardant which is known for use with ethylene oxide is carbon dioxide.
  • carbon dioxide because of the characteristics of carbon dioxide, a non- flammable ethylene oxide-carbon dioxide mixture contains less than 40 percent of the ethylene oxide per unit volume as does "12-88.” Thus, sterilization must be carried out either at higher pressures or for longer contact times.
  • the large difference in the vapor pressures of ethylene oxide and carbon dioxide causes the mixture to separate upon withdrawal from the storage tank or cylinder, raising the danger of delivering a sterilant mixture rich in carbon dioxide, which will not sterilize, or rich in ethylene oxide, which is explosive.
  • An improved sterilant mixture has now been found which employs ethylene oxide and overcomes the deficiencies of the known sterilants and provide for an improved sterilization method overcomes the deficiencies of the known sterilization methods.
  • a sterilant mixture comprising from about 20 to 35 mole percent ethylene oxide and from about 65 to 80 mole percent 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea).
  • the present invention also provides for a method for sterilizing an article comprising contacting the article with an effective amount of a sterilant mixture comprising from about 20 to 35 mole percent ethylene oxide and from about 65 to 80 mole percent 1,1,1,2,3,3,3-heptafluoropropane.
  • a sterilant mixture comprising from about 20 to 35 mole percent ethylene oxide and from about 65 to 80 mole percent 1,1,1,2,3,3,3-heptafluoropropane.
  • the gas mixture of this invention may be used with any compatible stabilizer including commonly employed sterilizers known to the art.
  • Figure 1 is a schematic representation of one sterilizer apparatus with which the method of the present invention may be employed.
  • Figure 2 is a graphical representation of flammability tests for one embodiment of the sterilant mixture of the present invention.
  • Figure 3 is a graphical representation of flammability tests for an ethylene oxide mixture formulated with the compound generally accepted as the substitute for CFC-12.
  • the present invention is a sterilant mixture and a method of sterilizing articles using the sterilant mixture.
  • the sterilant mixture is generally used as a gas or vapor.
  • the sterilant mixture of this invention comprises from about 20 to 35 mole percent, preferably from about 25 to 30 mole percent, ethylene oxide and from about 65 to 80 mole percent, preferably from about 70 to 75 mole percent.
  • the ethylene oxide acts as the active sterilizer while the halogenated compound, or compounds, if a mixture is employed, acts as a flame retardant. At flame retardant concentrations less than the specified minimum, sufficient flame retardency may not be present in the mixture to avoid a potentially dangerous situation, and at flame retardant concentrations greater than the specified maximum, effective sterilization may not be possible without the use of undesirably high temperatures, pressures and/or contact times.
  • the sterilant mixture of this invention comprises only ethylene oxide and HFC-227ea.
  • the sterilant mixture may, in addition, contain other substances so long as such substances do not negatively affect sterilant capabilities.
  • chlorodifluoromethane may also be present to increase the vapor pressure or reduce the cost of the sterilant mixture.
  • An increased vapor pressure may be desirable in some sterilization systems to propel the sterilant mixture into a sterilization chamber in a timely manner, particularly in a situation where the sterilant container temperature cannot be maintained at or about 21°C (70°F).
  • sterilant mixture of the invention include inert nitrogen gas which may also be used to increase the pressure in the sterilant container in order to propel the sterilant mixture into the sterilization chamber.
  • the sterilant mixture of this invention may be used to sterilize a great many articles including any article which has previously been sterilized using ethylene oxide mixtures.
  • medical equipment and materials which may be sterilized include diagnostic endoscopes; plastic goods such as syringes, gloves, test tubes, incubators and pacemakers; rubber goods such as tubing, catheters and sheeting; instruments such as needles, scalpels and oxygen tents; and other items such as dilators, pumps, motors and intraocular lenses.
  • the sterilant mixture of this invention may be used as a fumigant for items outside the medical field. These items include certain foodstuffs, such as spices, and other items such as furs, bedding, paper goods, and transportation equipment such as the cargo area of airplanes, trains and ships.
  • the sterilant mixture of this invention is effective against all forms of life, particularly unwanted insects, bacteria, virus, molds, fungi, and other microorganisms.
  • Among the most difficult organisms to kill is B. Subtilus sbs. niger spores; however; even these organisms are effectively destroyed by the sterilant mixture of the invention.
  • the sterilant mixture of this invention may be made using any effective mixing technique well known to those skilled in the art.
  • each compound of the mixture may be pumped gravimetrically through a manifold into a sterilant container, and the container rolled to intermix the compounds into a homogeneous mixture.
  • the compounds may be pumped into a mixing tank, recirculated in the tank until a fully homogeneous mixture is formed, and then pumped from the mixing tank into a sterilant container.
  • the sterilant mixture of this invention may be packaged in any container which is capable of holding the mixture including gas storage containers of suitable design such as U.S. Department of Transportation (DOT) Specification 4BA 240, 4BA 300, 4BW 240 or other DOT specification cylinders or trailers of suitable working pressure.
  • the sterilant mixture may also be packaged in American Society of Mechanical Engineers (ASME) storage vessels.
  • ASME American Society of Mechanical Engineers
  • the sterilant storage container may be delivered to the use site holding the sterilant mixture at a pressure generally within the range of from about 207 to 345 kPa at 21°C (30 to 50 pounds per square inch absolute (psia) at 70°F), and connected through a series of valves, control valves, vaporizer and appropriate conduit to a sterilizer to carry out the sterilization.
  • FIG. 1 the item or items to be sterilized are placed within sterilization chamber 1 through door 2.
  • Sterilizers such as illustrated in Figure 1 may range in size from desk-top models to room-size models and even larger.
  • the chamber is heated generally to a temperature within the range of from 54°C to 60°C (130°F to MOT). Generally, the higher the temperature the shorter is the required exposure time.
  • a partial vacuum is drawn inside the chamber by pumping out air through vent 8 by vacuum pump 9.
  • the air removal serves both to prevent dilution of the sterilant mixture and to reduce the exposure pressure. Creating the appropriate vacuum generally takes from about 5 to 45 minutes depending on the item to be sterilized since some items can be damaged by sudden pressure changes. Since a moist microorganism is more susceptible to the reaction of the sterilant, water vapor is employed. In Figure 1, water vapor from steam source 10 may be injected into chamber 1 through conduit 11. The water vapor is used to create relative humidity within the chamber within the range of from 30 to 80 percent.
  • Sterilant mixture is passed from a source such as cylinder 3 through conduit 4 and filters 5 to vaporizer 6 wherein it is converted to a vapor. From vaporizer 6, the sterilant mixture is passed through conduit 7 into sterilization chamber 1 for the sterilization.
  • the pressure at which the sterilization takes place within chamber 1 may be from about 48 to 228 kPa (7 to 33 psia).
  • the sterilization time will vary and is dependent upon a number of factors including temperature, pressure, humidity level, the specific sterilant mixture employed, and the material being sterilized. For example, some porous articles require shorter exposure time than do articles sealed in polyethylene bags. Moreover, some bacteria are especially resistant and thus take longer to destroy.
  • the sterilant mixture is evacuated from the chamber by flushing with air, nitrogen, steam or carbon dioxide through inlet 12 and successive evacuation through conduit 8 by pump 9.
  • the sterilized material is then removed from chamber 1 through door 2 and, if necessary, aerated for the removal of residual sterilant, before being used.
  • the entire sterilization procedure may be monitored and controlled through control panel 13.
  • a sterilant mixture In order for a sterilant mixture to be non-flammable, it must be non ⁇ flammable at all concentrations of air, i.e. from 0 to 100 percent air. Thus, a straight line representing 0 to 100 percent air cannot cross below the flammability curve. A straight line from 0 to 100 percent air just tangent to but not crossing below the flammability curve represents the highest ethylene oxide concentration while maintaining the mixture non-flammable. Such straight line is drawn in Figure 2 and shows that for ethylene oxide HFC-227ea mixtures, the ethylene oxide concentrations can be up to 27.6 mole percent and yet the mixture remains non ⁇ flammable for all concentrations of air.

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  • Health & Medical Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Epidemiology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Apparatus For Disinfection Or Sterilisation (AREA)
  • Agricultural Chemicals And Associated Chemicals (AREA)

Abstract

L'invention se rapporte à un mélange d'agents stérilisateurs comprenant 20 à 35 pour cent en mole d'oxyde d'éthylène et de 65 à 80 pour cent en mole de 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), et à un procédé de stérilisation utilisant ce mélange.
PCT/US1994/005655 1994-05-19 1994-05-19 Melange d'agents sterilisateurs et procede de sterilisation WO1995032007A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/US1994/005655 WO1995032007A1 (fr) 1994-05-19 1994-05-19 Melange d'agents sterilisateurs et procede de sterilisation

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1994/005655 WO1995032007A1 (fr) 1994-05-19 1994-05-19 Melange d'agents sterilisateurs et procede de sterilisation

Publications (1)

Publication Number Publication Date
WO1995032007A1 true WO1995032007A1 (fr) 1995-11-30

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Family Applications (1)

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PCT/US1994/005655 WO1995032007A1 (fr) 1994-05-19 1994-05-19 Melange d'agents sterilisateurs et procede de sterilisation

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999042143A1 (fr) * 1998-02-19 1999-08-26 Alliedsignal Inc. Compositions gazeuses sterilisantes d'oxyde d'ethylene, de pentafluoroethane et d'heptafluoropropane
WO2001051097A3 (fr) * 2000-01-10 2002-10-10 Honeywell Int Inc Procede d'utilisation de melanges contenant de l'oxyde d'ethylene non-inflammable destines a desinfecter par fumigation des microbes causant des degats au metal

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0566892A2 (fr) * 1992-04-21 1993-10-27 Hoechst Aktiengesellschaft Mélange de gaz stérilisants
WO1993023086A1 (fr) * 1992-05-08 1993-11-25 Allied-Signal Inc. Sterilisation a l'aide de compositions gazeuses d'oxyde d'ethylene et d'heptafluoropropane
WO1994006481A1 (fr) * 1992-09-21 1994-03-31 Great Lakes Chemical Corporation Melange de sterilisation sans danger pour la couche d'ozone

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0566892A2 (fr) * 1992-04-21 1993-10-27 Hoechst Aktiengesellschaft Mélange de gaz stérilisants
WO1993023086A1 (fr) * 1992-05-08 1993-11-25 Allied-Signal Inc. Sterilisation a l'aide de compositions gazeuses d'oxyde d'ethylene et d'heptafluoropropane
WO1994006481A1 (fr) * 1992-09-21 1994-03-31 Great Lakes Chemical Corporation Melange de sterilisation sans danger pour la couche d'ozone

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999042143A1 (fr) * 1998-02-19 1999-08-26 Alliedsignal Inc. Compositions gazeuses sterilisantes d'oxyde d'ethylene, de pentafluoroethane et d'heptafluoropropane
AU748962B2 (en) * 1998-02-19 2002-06-13 Honeywell International, Inc. Sterilizing gas compositions of ethylene oxide, pentafluoroethane and heptafluoropropane
US6432357B1 (en) 1998-02-19 2002-08-13 Honeywell International Inc. Sterilizing gas compositions of ethylene oxide, pentafluoroethane and heptafluoropropane
WO2001051097A3 (fr) * 2000-01-10 2002-10-10 Honeywell Int Inc Procede d'utilisation de melanges contenant de l'oxyde d'ethylene non-inflammable destines a desinfecter par fumigation des microbes causant des degats au metal
AU776186B2 (en) * 2000-01-10 2004-09-02 Honeywell International, Inc. Method using ethylene oxide to fumigate corrosion promoting microbes

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