Classification of Chemical Indicators

In my one of the blog I discussed about the different Sterilization methods which we use in pharmaceutical industries. Moist heat, dry heat and membrane filtration methods are used in majority of companies. For example in case of moist heat sterilization there are three basic parameters we need to check during sterilization process. These are temperature, pressure and time. Any process would be called successful if all these parameters are met. So, to monitor these parameters in sterilization process we require chemical indicators.

Chemical indicators have six different classes.

Class 1 chemical indicators: These indicators are also called process indicators. These are used to check whether required temperature has reached to the particular load or not. Example of this class is indicator tape, indicator labels etc. These tapes or labels are pasted on the each article of the load which we sterilize. After completion of the sterilization cycles we can check that whether the load has attained required temperature or not by observing the change in colour of the indicator tape like some indicator tapes changes colour form light yellow to black or from light green to dark green. By these indicator tapes we can also differentiate between processed and unprocessed load.

Class 2 chemical indicators: These indicators are used in specific test. Bowie dick test is the example of this class of chemical indicator. In bowie dick test we check the heat penetration. If steam properly penetrate in the load then there will be uniform colour change of the chemical indicator sheet which is used in this process otherwise if colour change is not uniform it means air pockets are present inside the load or autoclave chamber. So by this chemical indicator, we can assure that heat penetration is properly taking place within the load.

Class 3 chemical indicators: These are those indicators which comply one of the critical parameter of the sterilization process. These are also called single variable indicators. For example we can use a pellet tube which contains a specific chemical which melts at particular temperature. So by this chemical we can assure that particular temperature has been reached to the load which causes melting of this chemical.

Class 4 chemical indicators: These are the indicators which comply two or more critical parameters of the sterilization process. These are also called multi variable indicators.

Class 5 chemical indicators: These indicators are also called integrator. These types of indicator met all the three critical parameters of the sterilization process. These are very accurate chemical indicators.

Class 6 chemical indicators: This is the most accurate class of chemical indicators which met all the three critical parameters of the sterilization process. But this class is little bit different from the integrator because this is accurate that the class 5 indicators. 

All these indicators are very important tool for the monitoring of the sterilization process so have a continue watch over each sterilization cycle with these chemical indicators.

Thanks