Compound Clioquinol Topical Powder
» Compound Clioquinol Topical Powder contains not less than 22.5 percent and not more than 27.5 percent of C9H5ClINO.
Clioquinol 250 g
Lactic Acid 25 g
Zinc Stearate 200 g
Lactose 525 g
To make 1000 g
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
USP Clioquinol RS Click to View Structure
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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Topic/Question Contact Expert Committee
Monograph Behnam Davani, Ph.D., M.B.A.
Senior Scientific Liaison
(SM12010) Monographs - Small Molecules 1
Reference Standards RS Technical Services
USP35–NF30 Page 2711