Medium: water; 500 mL.

Apparatus 1: 50 rpm.

Time: 20 minutes.

Monobasic ammonium phosphate solution— Dissolve 11.5 g of monobasic ammonium phosphate in 1000 mL of water. Adjust with 85% phosphoric acid to a pH of 3.1.

Mobile phase— Prepare a filtered and degassed mixture of Monobasic ammonium phosphate solution and acetonitrile (4:1). Make adjustments if necessary (see System Suitability under Chromatography 621).

Standard solution— Transfer 25.0 mg, accurately weighed, of USP Selegiline Hydrochloride RS to a 50-mL volumetric flask. Dissolve in and dilute with water to volume, and mix. Pipet 2.0 mL of this solution into a 100-mL volumetric flask, dilute with water to volume, and mix.

Test solution— At 20 minutes withdraw a 10-mL portion of the solution under test and centrifuge for 10 minutes at 3500 rpm.

Chromatographic system— The liquid chromatograph is equipped with a 205-nm detector and a 3.9-mm × 30-cm column that contains packing L1. Chromatograph the Standard solution, and record the peak responses. The relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 15 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the amount of C13H17N·HCl dissolved.

Tolerances— Not less than 80% (Q) of the labeled amount of C13H17N·HCl is dissolved in 20 minutes.

Buffer solution , Mobile phase, System suitability solution, and Chromatographic system—Proceed as directed in the test for Chromatographic purity under Selegiline Hydrochloride.

Standard solution— Transfer 10.0 mL of the System suitability solution to a 100-mL volumetric flask, dilute with Mobile phase to volume, and mix. Transfer 10.0 mL of this solution to a 20-mL volumetric flask, dilute with Mobile phase to volume, and mix.

Test solution— Use a portion of the supernatant obtained from the Assay preparation.

Procedure— Proceed as directed in the test for Chromatographic purity under Selegiline Hydrochloride. Calculate the percentage of each impurity, excluding methamphetamine hydrochloride, in the portion of Tablets taken by the formula: in which W is the weight, in mg, of the labeled content of selegiline hydrochloride in the portion of Tablets taken to prepare the Test solution, and the other terms are as defined therein. Not more than 0.5% of any individual impurity is found, and the sum of all impurities, excluding methamphetamine hydrochloride, is not more than 2.0%.

Buffer solution , Mobile phase, System suitability solution, Test solution, and Chromatographic system—Proceed as directed in the test for Chromatographic purity under Selegiline Hydrochloride.

Standard solution— Transfer 10.0 mL of the System suitability solution to a 50-mL volumetric flask, dilute with Mobile phase to volume, and mix.

Procedure— Proceed as directed in the test for Chromatographic purity under Selegiline Hydrochloride. Calculate the percentage of methamphetamine hydrochloride in the portion of Tablets taken by the formula: in which C is the concentration, in mg per mL, of USP Methamphetamine Hydrochloride RS in the Standard solution, W is the weight, in mg, of the labeled content of selegiline hydrochloride in the portion of Tablets taken to prepare the Test solution, and rU and rS are the methamphetamine peak responses obtained from the Test solution and the Standard solution, respectively. Not more than 2.0% of methamphetamine hydrochloride is found.

Buffer solution , Mobile phase, Standard preparation, System suitability solution, and Chromatographic system—Proceed as directed in the test for Assay under Selegiline Hydrochloride.

Assay preparation— Weigh and powder not less than 20 Tablets. Transfer an accurately weighed portion of the powder equivalent to about 50 mg of selegiline hydrochloride to a 50-mL volumetric flask. Add 40 mL of Mobile phase, sonicate for 10 minutes, dilute with Mobile phase to volume, and mix. Centrifuge a 25-mL aliquot of this solution at 3500 rpm for 10 minutes. [note—Retain a portion of the supernatant for the Chromatographic purity and Limit of methamphetamine hydrochloride tests.] Transfer 10.0 mL of the supernatant to a 100-mL volumetric flask, dilute with Mobile phase to volume, and mix.

Procedure— Proceed as directed for Procedure in the Assay under Selegiline Hydrochloride. Calculate the quantity, in mg, of C13H17N·HCl in the portion of Tablets taken by the formula: in which the terms are as defined therein.