Medium: water; 900 mL.

Apparatus 2: 50 rpm.

Time: 45 minutes.

Mobile phase— Prepare a filtered and degassed mixture of dilute perchloric acid (1 in 20) and acetonitrile (7:3).

Standard solution— Dissolve an accurately weighed quantity of USP Methamphetamine Hydrochloride RS in water to obtain a solution having a known concentration similar to the one expected in the Test solution. Dilute 2:1 with 0.15 M perchloric acid.

Test solution— Use filtered aliquots of the solution under test. Dilute 2:1 with 0.15 M perchloric acid.

Procedure— The liquid chromatograph is equipped with a 211-nm detector and a 3.9-mm × 30-cm column that contains packing L1. The flow rate is about 2.5 mL per minute. Chromatograph the Standard solution (about 100 µL), record the chromatogram, and measure the response for the major peak: the tailing factor is not more than 1.5; and the relative standard deviation for replicate injections is not more than 3.0%. Inject an equal volume of the Test solution into the chromatograph, record the chromatogram, and measure the response of the major peak. Calculate the quantity of C10H15N·HCl dissolved by comparison with the Standard solution.

Tolerances— Not less than 75% (Q) of the labeled amount of C10H15N·HCl is dissolved in 45 minutes.

PROCEDURE FOR CONTENT UNIFORMITY—

Chloroform-saturated 0.1 N sulfuric acid— Shake 250 mL of 0.1 N sulfuric acid with 25 mL of chloroform for 10 minutes. Allow to stand for 1 hour with occasional shaking. Drain off the chloroform, and retain the chloroform-saturated sulfuric acid in a stoppered flask.

Standard preparation— Dissolve an accurately weighed quantity of USP Methamphetamine Hydrochloride RS in Chloroform-saturated 0.1 N sulfuric acid, and mix to obtain a solution having a known concentration of about 0.5 mg per mL.

Test preparation— Place 1 Tablet in a 125-mL separator, add 15 mL of water, and shake by mechanical means for 15 minutes to dissolve. Add 2.5 mL of 1 N sodium hydroxide, and shake. Extract the liberated methamphetamine with four 10-mL portions of chloroform, collecting the chloroform extracts in a second 125-mL separator. Transfer 10.0 mL of Chloroform-saturated 0.1 N sulfuric acid to the second separator, and shake by mechanical means for 10 minutes. Allow the layers to separate, and collect the aqueous layer.

Procedure— Concomitantly determine the absorbances of the Test preparation and the Standard preparation in 1-cm cells, at the wavelength of maximum absorbance at about 257 nm, with a suitable spectrophotometer, using Chloroform-saturated 0.1 N sulfuric acid as the blank. Calculate the quantity, in mg, of C10H15N·HCl in the Tablet taken by the formula: in which C is the concentration, in mg per mL, of USP Methamphetamine Hydrochloride RS in the Standard preparation; and AU and AS are the absorbances of the Test preparation and the Standard preparation, respectively.

(Official January 1, 2007)

Mobile phase, Standard preparation, and Chromatographic system— Proceed as directed in the Assay under Methamphetamine Hydrochloride.

Assay preparation— Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 10 mg of methamphetamine hydrochloride, to a 50-mL volumetric flask. Add 20 mL of 0.12 M phosphoric acid, and sonicate for 5 minutes. Dilute with 0.12 M phosphoric acid to volume, mix, and filter.

Procedure— Separately inject equal volumes (about 20 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of methamphetamine hydrochloride (C10H15N·HCl) 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 preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.