Procedure
Apply 50 µL of the
Test solution, containing 500 µg of butorphanol tartrate, and 5 µL and 10 µL of the
Standard solution, containing 5 µg and 10 µg of
USP Butorphanol Tartrate RS, respectively, about 2 cm apart to a line parallel to and about 2 cm from the bottom of a thin-layer chromatographic plate (see
Chromatography 621) 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 chloroform, methanol, benzene, and ammonium hydroxide (85:25:20:5). Develop the chromatogram until the solvent front has moved about 10 cm above the line of application. Remove the plate, mark the solvent front, and allow the solvent to evaporate. Spray the plate with
Iodoplatinate spray reagent. Estimate the percentage of the impurities present in the
Test solution by comparing the intensities of secondary spots, if present, with the intensities of the principal spots obtained from the chromatograms of the
Standard solution. The sum of the impurities observed is not greater than 2.0%.