Compound Clioquinol Topical Powder
» Compound Clioquinol Topical Powder contains not less than 22.5 percent and not more than 27.5 percent of C9H5ClINO.
Mix the Lactic Acid with the Lactose, then add the Clioquinol and the Zinc Stearate, and mix.
Packaging and storage Preserve in well-closed, light-resistant containers.
USP Reference standards 11
Identification Place a quantity of Topical Powder, equivalent to about 30 mg of clioquinol, in a glass-stoppered, 50-mL conical flask, add 20 mL of 1 N sulfuric acid, and shake for 5 minutes. Filter, transfer 5 mL of the filtrate to a glass-stoppered test tube, add 5 drops of potassium dichromate TS and 2 mL of chloroform, and shake well: a red-violet color develops in the chloroform layer.
Assay Transfer an accurately weighed quantity of Topical Powder, equivalent to about 50 mg of clioquinol, to a 200-mL volumetric flask, add 100 mL of 3 N hydrochloric acid, and shake by mechanical means for 15 minutes. Dilute with 3 N hydrochloric acid to volume, and mix. Filter a portion of the solution, dilute 4.0 mL of the filtrate with 3 N hydrochloric acid to 200.0 mL, and mix. Concomitantly determine the absorbances of this solution and of a Standard solution of USP Clioquinol RS in the same medium having a known concentration of about 5 µg per mL in 1-cm cells at the wavelength of maximum absorbance at about 267 nm, with a suitable spectrophotometer, using 3 N hydrochloric acid as the blank. Calculate the quantity, in mg, of C9H5ClINO in the portion of Topical Powder taken by the formula:
10C(AU / AS)in which C is the concentration, in µg per mL, of USP Clioquinol RS in the Standard solution; and AU and AS are the absorbances of the solution from the Topical Powder and the Standard solution, respectively.
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USP35NF30 Page 2711