Steam-formaldehyde sterilization indicator

• US 4,298,569 A
• Filed: 01/28/1980
• Issued: 11/03/1981
• Est. Priority Date: 03/11/1977
• Status: Expired due to Term

• Current Assignee: 3M Company
• Original Assignee: 3M Company
• Inventors: Read, David M.
• Primary Examiner(s): YASICH, DANIEL
• Application Number:
  US06/115,785
• Time in Patent Office: 645 Days
• Field of Search: 116/206, 422/56, 422/57, 422/27, 422/36, 252/408 R
• US Class Current: 422/27
• 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
• CPC Class Codes: G01N 31/226 for investigating the degree of sterilisation

Abstract

Indicators for the steam-formaldehyde sterilization process are provided which undergo a color change when placed in a steam-formaldehyde environment.

Claims

1. A method for indicating that an article has undergone steam-formaldehyde sterilization which comprises attaching an indicator to an article, said indicator comprising a substrate carrying a dye which will undergo an irreversible color change when exposed to formaldehyde vapor in the presence of low temperature steam and wherein a buffering agent is mixed with said dye and said buffer has a pH of from 4 to 6, and then inserting said article with indicator into an environment wherein the article and indicator are exposed to steam and formaldehyde so that the article is sterilized wherein said steam is between 60°

and 80°

C. and where said indicator will not change color when exposed to 134°

C. steam in the absence of formaldehyde for 31/2 minutes.

2. The method of claim 1 wherein said dye and buffering agent are mixed in a binder.

3. The method of claim 1 or 2 wherein said dye comprises 3,3'"'"'-[4,4'"'"'-bisphenylylene-(azo)] bis [4-amino-1-naphthalene].

4. The method of claim 1 or 2 wherein said dye comprises Congo Red.

5. A method for indicating that an article has undergone steam-formaldehyde sterilization which comprises attaching the indicator of claim 1 to an article which requires sterilization and inserting said article with indicator into a steam-formaldehyde sterilization chamber.