A: Dissolve a suitable quantity in water to obtain a solution containing 4mg per mL.Apply 10µLof this solution and 10µLof an aqueous Standard solution of USP Aurothioglucose RScontaining 4mg per mLto a suitable thin-layer chromatographic glass microfilament sheet (see Chromatography á621ñ)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 UVlight:the RFvalue 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 Assayadd barium chloride TS:a heavy,white precipitate is formed.

Test solution: 10mg per mL,in water.