Test solution:
20 mg per mL, in 0.1 N sodium hydroxide.
Assay
Mix about 500 mg, accurately weighed, of Biotin with 100 mL of water, add phenolphthalein TS, and titrate the suspension slowly with 0.1 N sodium hydroxide VS, while heating and stirring continuously. Each mL of 0.1 N sodium hydroxide is equivalent to 24.43 mg of C10H16N2O3S.