Medium: water; 500 mL.

Apparatus 2: 50 rpm.

Time: 15 minutes.

Procedure— Place 1 Capsule 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 15 minutes. If 1 or 2 of the Capsules rupture in more than 15 but not more than 30 minutes, repeat the test on 12 additional Capsules. Not more than 2 of the total of 18 Capsules tested rupture in more than 15 but not more than 30 minutes.

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

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

(Official January 1, 2007)

Mobile phase— Prepare a filtered and degassed mixture of acetonitrile and 0.01 M tetrabutylammonium dihydrogen phosphate (66:34). Make adjustments if necessary (see System Suitability under Chromatography 621).

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

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

Assay preparation— Transfer an accurately counted number of Capsules, equivalent to about 250 mg of docusate sodium, to a 250-mL volumetric flask, and add 50 mL of 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 50 mL of acetonitrile, and mix. Allow this solution to cool to room temperature, dilute with Diluent to volume, and mix. Transfer 5.0 mL of this solution to a 50-mL volumetric flask, dilute with Diluent to volume, mix, and filter, discarding the first 6 mL of the filtrate.

Chromatographic system (see Chromatography 621)—The liquid chromatograph is equipped with a 214-nm detector and a 4.6-mm × 15-cm column that contains packing L1 that has been highly deactivated (carbon loading of 30%). The flow rate is about 1.5 mL per 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 1000 theoretical plates, and the relative standard deviation is not more than 2%.

Procedure— Separately inject equal volumes (about 25 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C20H37NaO7S in each Capsule taken by the formula: in which C is the concentration, in mg per mL, of anhydrous docusate sodium in the Standard preparation, as determined from the concentration of USP Docusate Sodium RS corrected for moisture by a titrimetric water determination, N is the number of Capsules taken, and rU and rS are the docusate sodium peak responses obtained from the Assay preparation and the Standard preparation, respectively.