ETO Sterilisation Validation - EO Residual Minimum Sample Requirement


Involved In Discussions

Could some one help on rationale about the number of samples required for EO residual testing. I have checked standards (ISO 10993-7, 11135) and not found any requirements about how many samples you need to select for EO residual testing. So, does that mean I can test two samples or one sample would be enough. Our lab mentioned that as a minimum, two replicates for each product from each aeration time are recommended.

Also, we have mixed products, so can I put one sample from each product i.e. in one chamber I can put 2 different products (similar packaging but different product configurations) and take one sample from each product.



Super Moderator

Although not specifically spelled out by ISO 11135:2014, section 9.4.3, residuals testing can be regarded as a PPQ activity. In section you will find that "at least three" is the recommended number for demonstrating reproducibility.

So in case you can define a product configuration out of your portfolio, which is a worst case for potential residuals levels in terms of
  • product packaging,
  • presentation to the cycle (is there a potential worst-case location for residuals in the chambers that are emploeyed for preconditioning, sterilization and aeration?) and
  • cycle tolerances (is there a potential worst case for residuals, if precon, sterilization or aeration ran at maximum/minimum tolerances?)
you could test the one product configuration being a worst case / representative for other configurations with a minimum number samples, since you introduced an adequate margin of safety.




Involved In Discussions
Thanks Gerhard,

I agree with your opinion and rationale to demonstrate compliance. Your comments are much appreciated.

Thanks again.
Top Bottom