Abstract: Via setting up of two experimental groups,in which one composed of neutralizing agent and another without it,microbial inspection was carried out according to plate culture method that specified in China Hygienic Standard for Cosmetics.Experimental results on the colony detection of the two groups were compared.In the group with neutrazing agent added,10-fold dilution of cosmetics can be detected colonies,while in the group without neutralizing agent added,100-fold dilution of 18 cosmetics can be detected colonies,and 1 000-fold dilution of 2 creams can be detected colonies.Such results showed that the neutralizing agent can reduce the dilution of cosmetics when detection.Further,it was also found that TTC (2,3,5-triphenyl terazolium chloride) can inhibit the growth of bacteria in the cosmetics,so that TTC will affect the accuracy of the test results.It is recommended that verification test should be incorporated in the test standard;neutralizing agent should be added in the diluted solution of the cosmetics to reduce concentration of TTC in the culture medium;and 70% recovery of the test bacteria should be taken as the criteria for determining validity of the test.

Key words: cosmetics, microbial inspection, preservatives