Salicylic Acid Gel
» Salicylic Acid Gel is Salicylic Acid in a suitable viscous hydrophilic vehicle. It contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of C7H6O3. It may contain alcohol.
Packaging and storage— Preserve in collapsible tubes or in tight containers, preferably at controlled room temperature.
Identification— Filter 5 mL of the solution obtained by titration in the Assay. Add 1 mL of ferric chloride TS to the filtrate: a violet color is produced. Add 1 mL of 6 N acetic acid: the violet color does not change. Add 1 mL of 6 N hydrochloric acid: the violet color is discharged. A small amount of white precipitate may appear.
Alcohol content (if present) 611: from 90.0% to 110.0% of the labeled amount of C2H5OH.
Assay— To 25 mL of diluted alcohol add 1 drop of phenolphthalein TS and sufficient 0.1 N sodium hydroxide to produce a faint pink color. Add 5.0 g of Gel, accurately weighed, and stir. Titrate the dispersion with 0.1 N sodium hydroxide VS until a pink color is produced. [note—Reserve this solution for the Identification test.] Each mL of 0.1 N sodium hydroxide is equivalent to 13.81 mg of C7H6O3.
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Monograph Feiwen Mao, M.S.
(MDOOD05) Monograph Development-Ophthalmics Oncologics and Dermatologicals
USP32–NF27 Page 3532