A: Infrared Absorption á197Kñ.

B: It responds to the tests for Chloride á191ñ.

Test solution: 20mg per mL,in water.

Test solution: chloroform.

Standard solution: chloroform.

Eluant: a mixture of chloroform,cyclohexane,and diethylamine (5:4:1).

Visualization: 1.

Mobile phase— Prepare a degassed solution of 1.1g of sodium 1-heptanesulfonate in a mixture of water,methanol,and diluted glacial acetic acid (7in 50)(575:400:25).Adjust with the addition of acetic acid to a pHof 3.3±0.1,if necessary.Filter through a 0.5-µm disk.Make adjustments if necessary (seeSystem Suitabilityunder Chromatography á621ñ).

Standard preparation— Dissolve an accurately weighed quantity of USP Methamphetamine Hydrochloride RSin 0.12Mphosphoric acid,and dilute quantitatively and stepwise,with the aid of sonication if necessary,with 0.12Mphosphoric acid to obtain a solution having a known concentration of about 0.2mg per mL.

Assay preparation— Transfer about 20mg of Methamphetamine Hydrochloride,accurately weighed,to a 100-mLvolumetric flask,dissolve in and dilute with 0.12Mphosphoric acid to volume,and mix.

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 257-nm detector and a 3.9-mm ×30-cm column that contains packing L1.The flow rate is about 2mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the column efficiency determined from the analyte peak is not less than 1000theoretical plates;the tailing factor for the analyte peak is not more than 1.5;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 20µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of C10H15N·HCl in the portion of Methamphetamine Hydrochloride taken by the formula: in which Cis the concentration,in mg per mL,of USP Methamphetamine Hydrochloride RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.