Procedure
Apply 10-µL aliquots of the
Test and the
Standard solution to separate points on a thin-layer chromatographic plate (see
Chromatography 621) 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 solution is 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%.