A: Dissolve a suitable quantity in water to obtain a solution containing 4 mg per mL. Apply 10 µL of this solution and 10 µL of an aqueous Standard solution of USP Aurothioglucose RS containing 4 mg per mL to a suitable thin-layer chromatographic glass microfilament sheet (see Chromatography 621) impregnated with silicic acid and a suitable fluorescing substance. Allow the spots to dry, and develop the chromatogram in a solvent system consisting of a mixture of n-propyl alcohol, water, and ethyl acetate (3:3:1) until the solvent front has moved about three-fourths of the length of the plate. Remove the sheet from the developing chamber, mark the solvent front, and allow the solvent to evaporate. Locate the spots on the plate by examination under short-wavelength UV light: the RF value of the principal spot obtained from the solution under test corresponds to that obtained from the Standard solution.

B: To a portion of the filtrate obtained in the Assay add barium chloride TS: a heavy, white precipitate is formed.

Test solution: 10 mg per mL, in water.

(Official January 1, 2007)