Chemical Indicator

Chemical indicators show the specific sterilization conditions to which the package has been exposed at the point of placement. However, chemical indicators are designed to work within a specific temperature-time range and will never work correctly outside these ranges.
For example, if the temperature is above the recommended range, the indicator will change color earlier than expected due to localized overheating in the package.
Whereas at high temperature without sufficient humidity, microbial death will be much slower. The value of the information provided by chemical indicators depends on the class, number and location of the indicator in the sterilizer.
These indicators should be placed in areas identified during process validation that are representative of the entire sterilizer. If there is no required color change in a chemical indicator after the cycle, this should never be interpreted as the indicator not working, it should be considered as a failure in the sterilization process and the process should be reviewed for the following possible problems:

- Does the sterilizer have a malfunction that prevents it from reaching the specified values?
- Is there a change in the packaging material?
- Is there a change in the amount of material in the package?
- Has routine maintenance and calibration of the sterilizer been performed properly and on time?
- Was the correct sterilization program used?
- Was the chemical indicator used according to the manufacturer's recommendation?
- Is there an external problem that may affect the cycle of the sterilizer (such as vapor pressure, flow rate and non-condensed gases contained)?