Packaging and storage— Preserve in collapsible tubes or in well-closed, light-resistant containers.

USP Reference standards 11— USP Chlortetracycline Hydrochloride RS.

Minimum fill 755: meets the requirements.

Water, Method I 921: not more than 0.5%, 20 mL of a mixture of toluene and methanol (7:3) being used in place of methanol in the titration vessel.

Residual solvents 467: meets the requirements.

Assay— Proceed as directed under Antibiotics—Microbial Assays 81, using an accurately weighed quantity of Ointment, equivalent to about 30 mg of chlortetracycline hydrochloride, shaken in a separator with about 50 mL of ether, and extracted with four 20-mL portions of 0.01 N hydrochloric acid. Combine the aqueous extracts in a 100-mL volumetric flask, dilute with 0.01 N hydrochloric acid to volume, and mix. Dilute this stock solution quantitatively and stepwise with water to obtain a Test Dilution having a concentration assumed to be equal to the medium dose level of the Standard.

Expert Committee : (MDANT05) Monograph Development-Antibiotics

USP29–NF24 Page 498

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