Medium: 0.1 M pH 7.2 phosphate buffer prepared as directed under Solutions in the section Reagents, Indicators, and Solutions, except to use twice the stated quantities of the monobasic potassium phosphate solution and of the sodium hydroxide solution; 900 mL.

Apparatus 2: 50 rpm.

Time: 45 minutes.

Procedure— Filter 20 mL of the solution under test, and transfer 10.0 mL of the filtrate to a 100-mL volumetric flask. Dilute with Dissolution Medium to volume, and mix. Determine the absorbances of this solution and of a Standard solution prepared from USP Sulindac RS in the same medium, having a known concentration of about 20 µg per mL, in 1-cm cells at the wavelength of maximum absorbance at about 326 nm, using Dissolution Medium as the blank. Calculate the amount of C20H17FO3S dissolved by the formula: in which C is the concentration, in mg per mL, of sulindac in the Standard solution, and AU and AS are the absorbances of the solutions obtained from the specimen under test and the Reference Standard, respectively.

Tolerances— Not less than 80% (Q) of the labeled amount of C20H17FO3S is dissolved in 45 minutes.

Procedure for content uniformity— Using 1 finely powdered Tablet proceed as directed in the Assay, adjusting the degree of dilution used in preparing the Assay preparation to obtain a solution having a concentration of sulindac of about 0.5 mg per mL, and making appropriate corresponding changes in the calculation formula to account for the extent of dilution.

Mobile phase— Prepare as directed in the Assay.

Standard preparation— Dilute the Standard preparation prepared as directed in the Assay with Mobile phase to obtain a solution having a known concentration of about 15 µg per mL.

Test preparation— Prepare as directed for Assay preparation in the Assay.

Procedure— Proceed as directed for Procedure in the Assay. Measure the responses of the sulindac peak of the Standard preparation and of all peaks other than that of sulindac in the Test preparation. Calculate the amount, in mg, of related compounds in the portion of Tablets taken by the formula: in which C is the concentration, in µg per mL, of USP Sulindac RS in the Standard preparation, and rU and rS are the peak responses of the Test preparation and the Standard preparation, respectively: the limit is 3.0%, calculated on the basis of the Assay of sulindac in the portion of the Tablets taken.

(Official January 1, 2007)

Mobile phase— Prepare a mixture of chloroform, ethyl acetate, and acetic acid (approximately 38:5:1). Make adjustments if necessary (see System Suitability under Chromatography 621). Degas the solution.

Standard preparation— Dissolve an accurately weighed quantity of USP Sulindac RS in Mobile phase to obtain a solution having a known concentration of about 0.5 mg per mL.

Assay preparation— Weigh and finely powder not less than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 50 mg of sulindac, to a 100-mL volumetric flask. Add about 60 mL of Mobile phase, and shake by mechanical means for about 15 minutes. Dilute with Mobile phase to volume, mix, and centrifuge a portion of the mixture to obtain a clear supernatant.

Chromatographic system (see Chromatography 621)—The liquid chromatograph is equipped with a 332-nm detector and a 3.9-mm × 30-cm column that contains packing L3. The flow rate is about 2 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the tailing factor is not more than 1.5, the column efficiency is not less than 1650 theoretical plates, and the relative standard deviation for replicate injections is not more than 1.0%.

Procedure— Separately inject equal volumes (about 10 µL) of the Standard preparation and the Assay preparation into the chromatograph, and record the chromatograms. Measure the sulindac peak responses. Calculate the quantity, in mg, of C20H17FO3S in the portion of Tablets taken by the formula: in which C is the concentration, in mg per mL, of USP Sulindac RS in the Standard preparation, and rU and rS are the sulindac peak responses obtained from the Assay preparation and the Standard preparation, respectively.