A: Infrared Absorption 197S—

Solution: 50 mg per mL.

Medium: chloroform.

B: Ultraviolet Absorption 197U—

C: It responds to the tests for Chloride 191 when tested as specified for alkaloidal hydrochlorides.

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%.