A: Shake a quantity of Capsule contents,equivalent to about 300mg of phendimetrazine tartrate,with about 50mLof water,filter,and transfer the filtrate to a 200-mLseparator.Add 3mLof 12.5Nsodium hydroxide,and extract with two 50-mLportions of chloroform.Extract the combined chloroform extracts in a 250-mLseparator with two 15-mLportions of 0.5Nhydrochloric acid,and evaporate the combined aqueous extracts on a steam bath to dryness.Dissolve the residue in 5mLof acetone,and add 50mLof anhydrous ether to the solution.On standing,phendimetrazine hydrochloride crystallizes out.Filter the precipitate,wash with anhydrous ether,and dry at 105:the crystals so obtained melt between 189and 193,but the range between beginning and end of melting does not exceed 2.

B: Aportion of Capsule contents responds to the test for Tartrate á191ñ.

Medium: water;900mL.

Apparatus 1: 100rpm.

Time: 60minutes.

pH7.5Phosphate buffer— Prepare a solution of 0.025Mmonobasic potassium phosphate,and adjust with 1Npotassium hydroxide to a pHof 7.5.

Mobile phase— Prepare a suitable degassed and filtered mixture of acetonitrile and pH7.5Phosphate buffer(65:35).

Chromatographic system (see Chromatography á621ñ)— The liquid chromatograph is equipped with a 210-nm detector and a 4-mm ×15-cm column that contains packing L15.The flow rate is about 1mLper minute.Chromatograph three replicate injections of the Standard solution,and record the peak responses as directed for Procedure:the relative standard deviation is not more than 3.0%.

Procedure— Separately inject equal volumes (about 50µL)of the Standard solution and a filtered aliquot of the solution under test into the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the percentage of C12H17NO·C4H6O6dissolved in comparison with a Standard solution of USP Phendimetrazine Tartrate RS,similarly prepared and chromatographed.

Tolerances— Not less than 70%(Q)of the labeled amount of C12H17NO·C4H6O6is dissolved in 60minutes.

Mobile phase— Dissolve 1.1g of sodium 1-heptanesulfonate in 575mLof water,add 400mLof methanol,25mLof dilute acetic acid (14in 100),and mix.Adjust with glacial acetic acid to a pHof 3.0±0.1,if necessary.Filter through a 0.45-µm membrane filter,and degas.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Diluent— Prepare a mixture of water,methanol,and dilute acetic acid (14in 100)(57.5:40:2.5).

Internal standard solution— Prepare a solution of salicylamide in Diluenthaving a concentration of about 0.1mg per mL.

Standard preparation— Dissolve an accurately weighed quantity of USP Phendimetrazine Tartrate RSin Internal standard solution,and dilute quantitatively with Internal standard solutionto obtain a solution having a known concentration of about 0.7mg of USP Phendimetrazine Tartrate RSper mL.

Assay preparation— Remove,as completely as possible,the contents of not fewer than 20Capsules,and weigh accurately.Mix the combined contents,and transfer an accurately weighed quantity of the powder,equivalent to about 35mg of phendimetrazine tartrate,to a 50-mLvolumetric flask,add 25mLof Internal standard solution,and sonicate for about 15minutes.Cool the solution to room temperature,dilute with Internal standard solutionto volume,mix,and filter through a 0.45-µm membrane filter.

Chromatographic system (see Chromatography á621ñ)— The liquid chromatograph is equipped with a 256-nm detector and a 3.9-mm ×30-cm column that contains packing L1.The flow rate is about 1mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the resolution,R,between the analyte and internal standard peaks is not less than 3.0,and the relative standard deviation for replicate injections is not more than 1.0%.

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.The relative retention times are about 0.5for salicylamide and 1.0for phendimetrazine tartrate.Calculate the quantity,in mg,of C12H17NO·C4H6O6in the portion of Capsules taken by the formula: in which Cis the concentration,in mg per mL,of USP Phendimetrazine Tartrate RSin the Standard preparation,and RUand RSare the peak response ratios obtained from the Assay preparationand the Standard preparation,respectively.