Chromatographic purity—
Standard solutions—
To 20 mg of
USP Amodiaquine Hydrochloride RS in a glass-stoppered test tube add 1.0 mL of chloroform (saturated with ammonium hydroxide), and shake vigorously for 2 minutes. Allow the solids to settle, and decant the liquid into a second test tube
(Standard solution A). Prepare a second solution by diluting 1.0 volume of
Standard solution A with chloroform (saturated with ammonium hydroxide) to obtain 200 volumes of solution
(Standard solution B).
Test solution—
Dissolve 150 mg of Amodiaquine in 10 mL of chloroform (saturated with ammonium hydroxide).
Procedure—
Apply 10-µL portions of
Standard solution A, Standard solution B, and the
Test 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 chloroform (saturated with ammonium hydroxide) and dehydrated alcohol (9:1) 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, allow the solvent to evaporate, and examine the plate under short-wavelength UV light: the chromatograms show principal spots at about the same
RF value, and no secondary spot, if present in the chromatogram from the
Test solution, is more intense than the principal spot obtained from
Standard solution B.
Assay—
Transfer about 300 mg of Amodiaquine, accurately weighed, to a 200-mL volumetric flask, add 0.1 N hydrochloric acid to volume, and mix. Pipet 10.0 mL of the resulting solution into a 1000-mL volumetric flask, add 0.1 N hydrochloric acid to volume, and mix. Concomitantly determine the absorbances of this solution and a Standard solution of
USP Amodiaquine Hydrochloride RS in the same medium having a known concentration of about 15 µg per mL, in 1-cm cells at the wavelength of maximum absorbance at about 342 nm, with a suitable spectrophotometer, using 0.1 N hydrochloric acid as the blank. Calculate the quantity, in mg, of C
20H
22ClN
3O in the portion of Amodiaquine taken by the formula:
(355.87 / 428.79)(20C)(AU / AS),
in which 355.87 and 428.79 are the molecular weights of amodiaquine and anhydrous aminodiaquine hydrochloride, respectively;
C is the concentration, in µg per mL, calculated on the anhydrous basis, of
USP Amodiaquine Hydrochloride RS in the Standard solution; and
AU and
AS are the absorbances of the solution of amodiaquine hydrochloride and the Standard solution, respectively.
;)
-(diethylamino)-o-cresol
for 2 hours.