Procedure
Apply separate 20-µL portions of the
Standard solution,
Test solution 1,
Test Solution 2,
Reference solution 1, and
Reference solution 2 to a suitable thin-layer chromatographic plate (see
Thin-Layer Chromatography under
Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture. Allow the spots to dry, and develop the chromatograms in a solvent system consisting of the upper layer of a mixture of water, butyl alcohol, and glacial acetic acid (50:40:10) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, mark the solvent front, and allow the plate to air-dry. Examine the plate under short-wavelength UV light: the chromatograms from
Test solution 2 and the
Standard solution show principal spots at about the same
RF value. No secondary spot in the chromatogram from
Test solution 1, excluding the area at the point of application, is more intense than the principal spot obtained from
Reference solution 1 (0.3%), and not more than two secondary spots in the chromatogram from
Test solution 1 are more intense than the principal spot obtained from
Reference solution 2 (0.1%), and the total of all impurities detected in the chromatogram of
Test solution 1 is not more than 0.5%.