Ethylene oxide sterilization process indicator inks

• US 20040241862A1
• Filed: 06/29/2004
• Published: 12/02/2004
• Est. Priority Date: 06/24/2002
• Status: Active Grant

• Current Assignee: LA-CO Industries, Inc.
• Original Assignee: Shobha Shakher Puntambekar
• Inventors: Puntambekar, Shobha Shakher
• Granted Patent: US 7,141,214 B2
• Time in Patent Office: Days
• US Class Current: 436/1
• CPC Class Codes: A61L 2/206 Ethylene oxide
• CPC Class Codes: A61L 2/28 Devices for testing the effectiveness or completeness of sterilisation, e.g. indicators which change colour apparatus involving enzymes or microorganisms C12M1/34; methods involving enzymes or microorganisms C12Q1/00

Abstract

Water-based chemical indicator inks for ethylene oxide sterilization processes and methods for its use. The chemical indicator ink contains at least one pH indicator dye selected from the group consisting of Bromocresol green, Bromophenol blue, Methyl red, Ethyl orange, and combinations thereof. The pH indicator dye undergoes an irreversible color change when exposed to ethylene oxide vapor in the presence of low-temperature steam, but when exposed to other sterilization processes either does not undergo a color change or undergoes a color change that is different than is obtained when exposed to ethylene oxide.

Claims

1. A water-based chemical indicator ink for ethylene oxide sterilization processes containing at least one pH indicator dye selected from the group consisting of Bromocresol green, Bromophenol blue, Methyl red, Ethyl orange, and combinations thereof.

2. The water-based chemical indicator ink of claim 1 wherein said at least one pH indicator dye undergoes an irreversible color change when exposed to ethylene oxide vapor in the presence of low-temperature steam.

3. The water-based chemical indicator ink of claim 2 wherein said low-temperature steam has a temperature of less than about 145°

F.

4. The water-based chemical indicator ink of claim 1 wherein said at least one pH indicator dye does not undergo a color change when exposed to formaldehyde gas, high-temperature steam, dry heat, or combinations thereof.

5. The water-based chemical indicator ink of claim 2 wherein said at least one pH indicator dye undergoes a color change when exposed to formaldehyde gas, high-temperature steam, dry heat, or combinations thereof, that is different than is obtained when exposed to ethylene oxide vapor.

6. The water-based chemical indicator ink of claim 1 wherein said water-based chemical indicator ink is an aqueous ink solution.

7. The water-based chemical indicator ink of claim 6 wherein said aqueous ink solution comprises said at least one pH indicator dye dissolved in water.

8. The water-based chemical indicator ink of claim 1 further containing a powdered and crystallized hexahydrate metal salt.

9. The water-based chemical indicator ink of claim 1 further containing an acidic compound, wherein said acidic compound retards a color change of said water-based chemical indicator ink.

10. The water-based chemical indicator ink of claim 9 wherein said acidic compound is citric acid.

11. The water-based chemical indicator ink of claim 1 further containing at least one thickening agent.

12. The water-based chemical indicator ink of claim 11 wherein said at least one thickening agent is selected from the group consisting of hydrous aluminum silicates, hydrous magnesium silicates, and combinations thereof.

13. The water-based chemical indicator ink of claim 1 further comprising a white pigment.

14. The water-based chemical indicator ink of claim 13 wherein said white pigment is titanium dioxide.

15. The water-based chemical indicator ink of claim 1 further containing a binder.

16. The water-based chemical indicator ink of claim 15 wherein said binder is a polymeric material.

17. The water-based chemical indicator ink of claim 16 wherein said polymeric material is selected from the group consisting of polyvinyl alcohol, methyl cellulose, and combinations thereof.

18. The water-based chemical indicator ink of claim 1 further containing a foam suppressor.

19. The water-based chemical indicator ink of claim 18 wherein said foam suppressor is an aliphatic polyol blend.

20. A method for indicating that an article has undergone ethylene oxide sterilization processing comprising:

providing a water-based chemical indicator ink containing at least one pH indicator dye selected from the group consisting of Bromocresol green, Bromophenol blue, Methyl red, Ethyl orange, and combinations thereof, wherein said at least one pH indicator dye undergoes an irreversible color change when exposed to ethylene oxide vapor in the presence of low-temperature steam;

applying said water-based chemical indicator ink to an article;

subjecting said article to a concentration of ethylene oxide vapor in the presence of low-temperature steam; and

observing said water-based chemical indicator ink for a color change that is visually indicative of whether said concentration of ethylene oxide vapor has been applied for a time sufficient to sterilize said article.

21. The method of claim 20 further comprising measuring the integrated effect of subjecting said article to said concentration of ethylene oxide vapor in the presence of low-temperature steam for said time sufficient to sterilize said article.

22. The method of claim 20 further comprising applying said water-based chemical indicator ink to a substrate to form an ethylene oxide sterilization process indicator prior to applying said water-based chemical indicator ink to said article.

23. The method of claim 22 further comprising printing said water-based chemical indicator ink on said substrate in the shape of squares or insignia to form said ethylene oxide sterilization process indicator.

24. The method of claim 22 further comprising securing said ethylene oxide sterilization process indicator to a package containing said article and subjecting said package to said concentration of ethylene oxide vapor in the presence of low-temperature steam.

25. The method of claim 20 further comprising providing said water-based chemical indicator ink containing said at least one pH indicator dye wherein said at least one pH indicator dye does not undergo a color change when exposed to formaldehyde gas, high-temperature steam, dry heat, or combinations thereof.

26. The method of claim 20 further comprising providing said water-based chemical indicator ink containing said at least one pH indicator dye wherein said at least one pH indicator dye undergoes a color change when exposed to formaldehyde gas, high-temperature steam, dry heat, or combinations thereof, that is different than is obtained when exposed to ethylene oxide vapor.

27. The method of claim 20 further comprising providing said water-based chemical indicator ink containing said at least one pH indicator dye and a powdered and crystallized hexahydrate metal salt.

28. The method of claim 20 further comprising providing said water-based chemical indicator ink containing said at least one pH indicator dye and an acidic compound, wherein said acidic compound retards a color change of said water-based chemical indicator ink.

29. The method of claim 28 wherein said acidic compound is citric acid.

30. The method of claim 20 further comprising providing said water-based chemical indicator ink containing said at least one pH indicator dye and at least one thickening agent.

31. The method of claim 30 wherein said at least one thickening agent is selected from the group consisting of hydrous aluminum silicates, hydrous magnesium silicates, and combinations thereof.

32. The method of claim 20 further comprising providing said water-based chemical indicator ink containing said at least one pH indicator dye and a white pigment.

33. The method of claim 32 wherein said white pigment is titanium dioxide.

34. The method of claim 20 further comprising providing said water-based chemical indicator ink containing said at least one pH indicator dye and a binder.

35. The method of claim 34 wherein said binder is a polymeric material.

36. The method of claim 35 wherein said polymeric material is selected from the group consisting of polyvinyl alcohol, methyl cellulose, and combinations thereof.

37. The method of claim 20 further comprising providing said water-based chemical indicator ink containing said at least one pH indicator dye and a foam suppressor.

38. The method of claim 37 wherein said foam suppressor is an aliphatic polyol blend.