Procedure
Apply 10-µLaliquots of the
Test and the
Standard solutionto separate points on a thin-layer chromatographic plate (see
Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel.Place the plate in a saturated chromatographic chamber,and develop the chromatogram in a solvent system consisting of a mixture of methyl isobutyl ketone,isopropyl alcohol,ethyl acetate,water,and ammonium hydroxide (50:45:35:18:3)until the solvent front has moved three-fourths of the length of the plate.Remove the plate from the developing chamber,air-dry,and expose it to iodine vapor:any spot,other than the principal spot,obtained from the
Test solutionis not greater in size and intensity than the spot produced by the
Standard solution(0.5%),and the sum of the impurities is not greater than 2.0%.