Medium: water;900mL.

Apparatus 1: 100rpm.

Time: 60minutes.

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

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 1.0mLper 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,Diluent,Internal standard solution,Standard preparation,and Chromatographic system— Prepare as directed in the AssayunderPhendimetrazine Tartrate Capsules.

Assay preparation— Weigh and finely powder not fewer than 20Tablets.Transfer an accurately weighed portion 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.

Procedure— Proceed as directed for Procedurein the Assayunder Phendimetrazine Tartrate Capsules.Calculate the quantity,in mg,of C12H17NO·C4H6O6in the portion of Tablets 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.