Medium: 0.1MpH7.2phosphate buffer prepared as directed under Solutionsin 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;900mL.

Apparatus 2: 50rpm.

Time: 45minutes.

Procedure— Filter 20mLof the solution under test,and transfer 10.0mLof the filtrate to a 100-mLvolumetric flask.Dilute with Dissolution Mediumto volume,and mix.Determine the absorbances of this solution and of a Standard solution prepared from USP Sulindac RSin the same medium,having a known concentration of about 20µg per mL,in 1-cm cells at the wavelength of maximum absorbance at about 326nm,using Dissolution Mediumas the blank.Calculate the amount of C20H17FO3Sdissolved by the formula: in which Cis the concentration,in mg per mL,of sulindac in the Standard solution,and AUand ASare 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 C20H17FO3Sis dissolved in 45minutes.

Procedure for content uniformity— Using 1finely powdered Tablet proceed as directed in the Assay,adjusting the degree of dilution used in preparing the Assay preparationto obtain a solution having a concentration of sulindac of about 0.5mg 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 preparationprepared as directed in the Assaywith Mobile phaseto obtain a solution having a known concentration of about 15µg per mL.

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

Procedure— Proceed as directed for Procedurein the Assay.Measure the responses of the sulindac peak of the Standard preparationand 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 Cis the concentration,in µg per mL,of USP Sulindac RSin the Standard preparation,and rUand rSare the peak responses of the Test preparationand the Standard preparation,respectively:the limit is 3.0%,calculated on the basis of the Assayof sulindac in the portion of the Tablets taken.

Mobile phase— Prepare a mixture of chloroform,ethyl acetate,and acetic acid (approximately 38:5:1).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).Degas the solution.

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

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

Chromatographic system (see Chromatography á621ñ)—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 2mLper 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 1650theoretical plates,and the relative standard deviation for replicate injections is not more than 1.0%.

Procedure— Separately inject equal volumes (about 10µL)of the Standard preparationand the Assay preparationinto the chromatograph,and record the chromatograms.Measure the sulindac peak responses.Calculate the quantity,in mg,of C20H17FO3Sin the portion of Tablets taken by the formula: in which Cis the concentration,in mg per mL,of USP Sulindac RSin the Standard preparation,and rUand rSare the sulindac peak responses obtained from the Assay preparationand the Standard preparation,respectively.