A: Mix an amount of the Capsule contents,equivalent to about 50mg of dextroamphetamine sulfate,with about 10mLof water for 30minutes,and filter into a small flask.Cool the filtrate to about 15,and proceed as directed in the Identificationtest under Dextroamphetamine Sulfate Elixir(Oral Solution,Official June 1,2005),beginning with “add 3mLof 1Nsodium hydroxide.”

B: The retention time of the major peak in the chromatogram of the Assay preparationis the same as that of the Standard preparationobtained in the Assay.

Medium: water;500mL.

Apparatus 1: 100rpm.

Time: 45minutes.

Procedure— Determine the amount of (C9H13N)2·H2SO4dissolved,employing the procedure set forth in the Assay,making any necessary modifications.

Tolerances— Not less than 75%(Q)of the labeled amount of (C9H13N)2·H2SO4is dissolved in 45minutes.

Mobile phase— Dissolve 1.1g of sodium 1-heptanesulfonate in 525mLof water.Add 25mLof dilute glacial acetic acid (14in 100)and 450mLof methanol.Adjust dropwise,if necessary,with glacial acetic acid to a pHof 3.3±0.1.Filter through a 0.5-µm membrane filter.The volume of methanol may be adjusted so that the retention time for dextroamphetamine is about 5minutes.

Standard preparation— Dissolve an accurately weighed quantity of USP Dextroamphetamine Sulfate RSin 0.12Nphosphoric acid to obtain a solution having a known concentration of about 0.3mg per mL.

Assay preparation— Remove,as completely as possible,the contents of not fewer than 20Capsules,and weigh.Transfer an accurately weighed portion of the mixed powder,equivalent to about 15mg of dextroamphetamine sulfate,to a 50-mLvolumetric flask.Add 40mLof 0.12Nphosphoric acid,and sonicate for 15minutes.Dilute with 0.12Nphosphoric acid to volume,and mix.Filter through a 0.5-µm membrane filter,discarding the first 20mLof the filtrate.

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 254-nm detector and a 3.9-mm ×30-cm column that contains packing L1.The flow rate is about 2mLper minute.Chromatograph three replicate injections of the Standard preparation,and record the peak responses as directed for Procedure:the relative standard deviation is not more than 2.0%.

Procedure— Separately inject equal volumes (about 50µL)of the Standard preparationand the Assay preparationinto the chromatograph by means of a suitable automatic injector or sampling valve,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of (C9H13N)2·H2SO4in the portion of Capsules taken by the formula: in which Cis the concentration,in mg per mL,of USP Dextroamphetamine Sulfate RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.