Decontamination methods (cleansing and sporicidal disinfection) should render the interior surfaces and critical zone of your isolator free of practical microorganisms. The look and advancement of the decontamination cycle usually occurs on completion in the OQ. USP3 all over again provides guidance on this matter as does PIC/S6 which https://tailinscitech.weebly.com/blog/vhp-sterilization-solutions-by-tailin-bioengineering-protecting-pharma-and-laboratory-environments