Identification—
Transfer 10 mL of Injection to a separator, add 2 mL of 2 N hydrochloric acid, extract with 10 mL of chloroform, filter, and evaporate the chloroform solution to about 2 mL. Carefully add ether until the liquid becomes turbid, heat on a steam bath to produce a clear solution, then cool, and allow to stand. Filter the crystalline precipitate, wash with ether, and dry in vacuum at 105
for 30 minutes: the precipitate so obtained responds to
Identification test
A under
Imipramine Hydrochloride.
Assay—
Transfer an accurately measured volume of Injection, equivalent to about 25 mg of imipramine hydrochloride, to a 100-mL volumetric flask, add 0.5 N hydrochloric acid to volume, and mix. Pipet 10 mL of this solution into a separator, add 10 mL of 1 N sodium hydroxide, and extract with four 20-mL portions of ether, shaking each portion for 2 minutes and collecting the extracts in a second separator. Extract the combined ether extracts with four 20-mL portions of 0.5 N hydrochloric acid, and combine the extracts in a 250-mL beaker. Aerate this solution with nitrogen to remove residual ether, then transfer to a 100-mL volumetric flask, and rinse the beaker with 0.5 N hydrochloric acid, collecting the rinsings in the flask. Add the 0.5 N acid to volume, and mix. Dissolve an accurately weighed quantity of
USP Imipramine Hydrochloride RS in 0.5 N hydrochloric acid, and dilute quantitatively and stepwise with the same solvent to obtain a Standard solution having a known concentration of about 25 µg per mL. Concomitantly determine the absorbances of both solutions in 1-cm cells at the wavelength of maximum absorbance at about 250 nm, with a suitable spectrophotometer, using 0.5 N hydrochloric acid as the blank. Calculate the quantity, in mg, of C
19H
24N
2·HCl in each mL of the Injection taken by the formula:
(C / V)(AU / AS),
in which
C is the concentration, in µg per mL, of
USP Imipramine Hydrochloride RS in the Standard solution;
V is the volume, in mL, of Injection taken; and
AU and
AS are the absorbances of the solution from the Injection and the Standard solution, respectively.
85
—
It contains not more than 5.0 USP Endotoxin Units per mg of imipramine hydrochloride.