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71
, except to place the filter on the surface of Soybean–Casein Digest Agar Medium in a Petri dish, incubate for 7 days at 30
to 35, and count the number of colonies on the filter. Similarly prepare a second specimen, except to incubate at 20 to 25. Not more than 20 colonies are observed from the two specimens. It meets also the requirements of the tests for absence of Staphylococcus aureus and Pseudomonas aeruginosa under Microbial Limit Tests 61.
921:
not more than 7.0%.
467:
meets the requirements.
81, using an accurately weighed portion of Topical Powder, equivalent to about 5000 USP Polymyxin B Units, shaken with 20 mL of water in a suitable volumetric flask. Dilute with Buffer No. 6 to volume, and mix. Dilute an accurately measured volume of the solution so obtained quantitatively with Buffer No. 6 to obtain a Test Dilution having a concentration of polymyxin B assumed to be equal to the median dose level of the Standard.
81, using an accurately weighed portion of Topical Powder, equivalent to about 800 USP Bacitracin Units, added to a 100-mL volumetric flask, dilute with 0.01 N hydrochloric acid to volume, and mix. Dilute this solution quantitatively with Buffer No. 1 to obtain a Test Dilution having a concentration assumed to be equal to the median dose level of the Standard. In preparing each test dilution of the Standard, add additional hydrochloric acid to each to obtain the same concentration of hydrochloric acid as in the Test Dilution.