A: Prepare a solution in methanol to contain 10mg of benzoyl peroxide per mL.Apply 5µLof this solution and 5µLof a freshly prepared Standard solution of Hydrous Benzoyl Peroxide,previously subjected to the Assay,in methanol containing 10mg per mLon a line parallel to and about 2.5cm from the bottom of a thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel mixture.Place the plate in a developing chamber containing,and equilibrated with,a mixture of toluene,dichloromethane,and glacial acetic acid (50:2:1).Develop the chromatogram until the solvent front has moved about three-fourths of the length of the plate.Remove the plate,and allow the solvent to evaporate.Observe the plate 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: Dissolve an accurately weighed quantity in acetonitrile to obtain a solution containing 0.32mg of benzoyl peroxide per mL.Chromatograph this test solution and a freshly prepared Standard solution of Hydrous Benzoyl Peroxide,previously subjected to the Assay,in acetonitrile containing 0.32mg per mLas directed in the test for Related compoundsunder Benzoyl Peroxide Gel:the solution under test exhibits a major peak for benzoyl peroxide,the retention time of which corresponds to that exhibited by the Standard solution.