Salicylic Acid Collodion
» Salicylic Acid Collodion contains not less than 9.5 percent and not more than 11.5 percent of C7H6O3.
Dissolve the Salicylic Acid in about 750 mL of Flexible Collodion, add sufficient of the latter to make the product measure 1000 mL, and mix.
Packaging and storage Preserve in tight containers, at controlled room temperature, remote from fire.
Assay Transfer to a 400-mL beaker 5 mL of Salicylic Acid Collodion, accurately measured, rinse the measuring device with three 10-mL portions of a mixture of ether and alcohol (3:1) that previously has been neutralized to bromothymol blue TS, and add the rinsings to the beaker. Add, with stirring, 5 mL of sodium lauryl sulfate solution (1 in 10) that previously has been neutralized with 0.1 N hydrochloric acid to the distinct yellow color of bromothymol blue TS, and finally add 20 mL of water. Mix, add 5 drops of bromothymol blue TS, and titrate the mixture with 0.1 N sodium hydroxide VS. Each mL of 0.1 N sodium hydroxide is equivalent to 13.81 mg of C7H6O3.