Chromatographic purity—
Adsorbent:
chromatographic silica gel mixture.
Test solution—
Transfer about 250 mg of Nortriptyline Hydrochloride, accurately weighed, to a 10-mL volumetric flask. Dissolve in and dilute with methanol to volume, and mix.
Standard solutions—
Dissolve an accurately weighed quantity of
USP Nortriptyline Hydrochloride RS in methanol, and dilute quantitatively, and stepwise if necessary, with methanol to obtain a solution having a known concentration of about 25.0 mg per mL (
Standard solution A). Dilute appropriate portions of this solution with methanol to obtain
Standard solutions B,
C,
D,
E, and
F having known concentrations of 125, 75, 50, 25, and 12.5 µg per mL, respectively. The final concentrations of
Standard solutions B,
C,
D,
E, and
F represent 0.5%, 0.3%, 0.2%, 0.1%, and 0.05% of
Standard solution A concentration, respectively.
Application volume:
5 µL.
Developing solvent system:
a mixture of acetonitrile, methanol, and ammonium hydroxide (10:1:1).
Procedure—
Apply equal volumes of the
Test solution and
Standard solutions A,
B,
C,
D,
E, and
F as directed in
Ordinary Impurities 
466
. Examine the plate under short-wavelength UV light, then spray the plate with Dragendorff's TS, dry the plate with a stream of nitrogen, and then spray with
hydrogen peroxide TS: any secondary spot at an
RF value of 0.78 relative to the nortriptyline spot in the
Test solution is not greater than the principal spot for
Standard solution D; any other secondary spot in the
Test solution is not more than 0.1%; and the sum of all secondary spots is not more than 0.5%.
Assay—
Dissolve about 600 mg of Nortriptyline Hydrochloride, accurately weighed, in 50 mL of glacial acetic acid, add 10 mL of
mercuric acetate TS, and titrate with 0.1 N perchloric acid VS, determining the endpoint potentiometrically. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 29.98 mg of C
19H
21N·HCl.
;)
-propylamine hydrochloride
and 220