Chromatographic purity
Dissolve an accurately weighed quantity in a solvent mixture consisting of toluene and methanol (1:1), to obtain a solution having a known concentration of about 7 mg of the test specimen per mL. Similarly prepare a Standard solution of
USP Azatadine Maleate RS in the same medium having a known concentration of about 7 mg per mL. Apply 100-µL portions of the test solution and the Standard solution to a suitable thin-layer chromatographic plate (see
Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture. Allow the spots to dry, and develop the chromatogram in a solvent system consisting of a mixture of toluene, isopropyl alcohol, and diethylamine (10:10:1), 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. Locate the spots on the plate by visualization under short-wavelength UV light. Separately transfer the silica gel mixture containing the principal spot from each track to suitable stoppered centrifuge tubes.
[NOTETake care to separate the principal spots from any adjacent spots.
] Similarly transfer an equal amount of silica gel from a blank section of the plate to a separate, suitable stoppered centrifuge tube. To each of the three tubes add 15.0 mL of a solvent mixture consisting of methanol and 0.5 N hydrochloric acid (4:1), shake vigorously for about 15 minutes, and centrifuge. Concomitantly determine the absorbances of the supernatant test solution and the Standard solution in 1-cm cells at the wavelength of maximum absorbance at about 284 nm, with a suitable spectrophotometer, using the solution obtained from the blank section of the plate as the blank. Calculate the chromatographic purity taken by the formula:
100(AU / AS)(CS / CU),
in which
AU and
AS are the absorbances of the test solution and the Standard solution, respectively; and
CS and
CU are the concentrations, in mg per mL, of the Standard solution and the test solution, respectively. The chromatographic purity is not less than 98.0%.
Assay
Dissolve about 650 mg of Azatadine Maleate, accurately weighed, in 50 mL of glacial acetic acid, add 2 drops of
crystal violet TS, and titrate with 0.1 N perchloric acid VS. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 26.13 mg of C
20H
22N
2·2C
4H
4O
4.