Medium: water;500mL.

Apparatus 2: 50rpm.

Time: 15minutes.

Procedure— Place 1Capsule in each vessel,and allow the Capsule to sink to the bottom of the vessel before starting rotation of the blade.Observe the Capsules,and record the time taken for each capsule shell to rupture.

Tolerances— The requirements are met if all of the Capsules tested rupture in not more than 15minutes.If 1or 2of the Capsules rupture in more than 15but not more than 30minutes,repeat the test on 12additional Capsules.Not more than 2of the total of 18Capsules tested rupture in more than 15but not more than 30minutes.

SOLID-FILLED CAPSULES :meet the requirements for Content Uniformity.

SOLUTION-FILLED CAPSULES :meet the requirements for Weight Variation.

Mobile phase— Prepare a filtered and degassed mixture of acetonitrile and 0.01Mtetrabutylammonium dihydrogen phosphate (66:34).Make adjustments if necessary (seeSystem Suitability under Chromatography á621ñ).

Diluent— Prepare a mixture of acetonitrile and water (50:50).

Standard preparation— Dissolve an accurately weighed quantity of USP Docusate Sodium RSin Diluentto obtain a solution having a known concentration of about 1mg per mL.Pipet 5.0mLof this solution into a 50-mLvolumetric flask,dilute with Diluentto volume,mix,and filter,discarding the first 6mLof the filtrate.

Assay preparation— Transfer an accurately counted number of Capsules,equivalent to about 250mg of docusate sodium,to a 250-mLvolumetric flask,and add 50mLof water.Heat the mixture with occasional swirling until the capsule shells have ruptured and dissolved.[NOTE—Take special care to assure that all of the Capsules have ruptured.]Remove from heat,add 50mLof acetonitrile,and mix.Allow this solution to cool to room temperature,dilute with Diluentto volume,and mix.Transfer 5.0mLof this solution to a 50-mLvolumetric flask,dilute with Diluentto volume,mix,and filter,discarding the first 6mLof the filtrate.

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 214-nm detector and a 4.6-mm ×15-cm column that contains packing L1that has been highly deactivated (carbon loading of 30%).The flow rate is about 1.5mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed under Procedure:the tailing factor is not more than 2.0,the column efficiency for the analyte peak is not less than 1000theoretical plates,and the relative standard deviation is not more than 2%.

Procedure— Separately inject equal volumes (about 25µL)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 C20H37NaO7Sin each Capsule taken by the formula: in which Cis the concentration,in mg per mL,of anhydrous docusate sodium in the Standard preparation,as determined from the concentration of USP Docusate Sodium RScorrected for moisture by a titrimetric water determination,Nis the number of Capsules taken,and rUand rSare the docusate sodium peak responses obtained from the Assay preparationand the Standard preparation,respectively.