A: Infrared Absorption 197M.

B: The RF value of the principal spot in the chromatogram of the Identification corresponds to that of Standard preparation A as obtained in the test for Chromatographic purity.

Standard solutions— Dissolve USP Antazoline Phosphate RS in methanol, and mix to obtain a solution having a known concentration of 0.10 mg per mL. Quantitatively dilute with methanol to obtain 5 Standard solutions having the following compositions:

Test solution— Dissolve an accurately weighed quantity of Antazoline Phosphate in methanol to obtain a solution containing 10 mg per mL.

Identification solution— Dilute a portion of the Test solution quantitatively with methanol to obtain a solution containing 50 µg per mL.

Procedure— Apply separately 10 µL of the Test solution, 10 µL of the Identification solution, and 10 µL of each Standard solution to a suitable thin-layer chromatographic plate (see Chromatography 621), coated with a 0.25-mm layer of chromatographic silica gel mixture. Position the plate in a chromatographic chamber, and develop the chromatograms in a solvent system consisting of a mixture of ethyl acetate, methanol, and diethylamine (17:2:1) 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 solvent to evaporate. Examine the plate under short-wavelength UV light, and compare the intensities of any secondary spots observed in the chromatogram of the Test solution with those of the principal spots in the chromatograms of the Standard solutions. [note—Disregard any spots observed at the origins of the chromatograms.] No secondary spot from the chromatogram of the Test solution is larger or more intense than the principal spot obtained from Standard solution A (0.5%), and the sum of the intensities of all secondary spots obtained from the Test solution corresponds to not more than 1.0%.