There is no "standard procedure" in this application. By variable "pass" criteria,, USP 51 protocol (http://www.uspbpep.com/usp29/v29240/usp29nf24s0_c51.html ) is used by some and effectively recognized by some regulatory/standardization bodies. However testing by those most expert in cosmetic microbiology risk assessment application consider different protocol design - often proprietary - better described by the "CTFA method"

Thank you very much Phil Geis.

Hi

I think you need to read Challenge test in chapter 51 in USP and chapter 14 in book ( Principles and Practice of Disinfection,Preservation & Sterilization)

good luck

Thanks Abu El-Wafa .