A: Infrared Absorption á197Kñ.

B: It responds to the test for Tartrate á191ñ.

Mobile phase— Prepare a mixture of 20mLof 10%tetramethylammonium hydroxide and 5mLof phosphoric acid,dilute with water to a volume of 1000mL,and mix.To 896mLof the resulting solution add 100mLof methanol,4mLof tetrahydrofuran,and mix.Filter and degas the mixture.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard solution A— Dissolve accurately weighed quantities of USP Phenylpropanolamine Hydrochloride RSand USP Dextroamphetamine Sulfate RSin water to obtain a solution having known concentrations of about 100mg of USP Phenylpropanolamine Hydrochloride RSper mLand 1µg of USP Dextroamphetamine Sulfate RSper mL.

Standard solution B— Dissolve an accurately weighed quantity of USP Phenylpropanediol RSin water,and dilute quantitatively,and stepwise if necessary,with water to obtain a solution having a known concentration of about 0.1mg per mL.

Resolution solution— Dissolve accurately weighed quantities of USP Phenylpropanolamine Hydrochloride RSand USP Dextroamphetamine Sulfate RSin water to obtain a solution containing about 5µg of each per mL.

Test solution— Transfer about 1000mg of Phenylpropanolamine Bitartrate,accurately weighed,to a 10-mLvolumetric flask,dilute with water to volume,and mix.

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 215-nm detector and a 4.6-mm ×15-cm column that contains spherical 5-µm packing L1.The flow rate is about 2.0mLper minute.Separately chromatograph the Resolution solutionand each Standard solution,and record the peak responses as directed for Procedure:the relative retention times are about 1.0for phenylpropanolamine,between 1.9and 2.1for dextroamphetamine,and between 2.3and 2.7for phenylpropanediol;the resolution,R,between phenylpropanolamine and dextroamphetamine in the chromatogram of the Resolution solutionis not less than 5.0;and the relative standard deviation for replicate injections of the Standard solutionsis not more than 3.0%.

Procedure— Separately inject equal volumes (about 20µL)of Standard solution A,Standard solution B,and the Test solutioninto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the percentage of phenylpropanediol in the portion of Phenylpropanolamine Bitartrate taken by the formula: in which Cis the concentration,in mg per mL,of USP Phenylpropanediol RSin Standard solution B;Wis the weight,in mg,of Phenylpropanolamine Bitartrate taken to prepare the Test solution;and rUand rSare the peak responses obtained from the Test solutionand the Standard solution B,respectively.The limit of phenylpropanediol is not more than 0.2%.

(343.34/368.49)(C/W)(rU/rS),