Establishment and Validation of Microbial Limit Test of Phenol Ear Drops

OBJECTIVE To establish a method for microbial limit test of Phenol Ear drops and to verify this method. METHODS The method for microbial limit examination in Chinese Pharmacopoeia (2010) was followed, involving conventional method and membrane filtration method. The validation had been tested by recovery. RESULTS Combination of membrane filtration and neutralization, recoveries of Escherichia coli, Staphylococcus aureus and Bacillus subtilis were >70%. Combination of conventional method and neutralization, recoveries of Candida albicans and Aspergillus niger were >70%. CONCLUSION Combination of membrane filtration and neutralization can be applied to bacteria counting, while combination of conventional method and neutralization is used to moulds and yeasts counting as well as controlled bacterium.