A: Transfer a quantity of finely powdered Tablets,equivalent to about 100mg of dapsone,to a suitable container,add 5mLof acetone,shake for 5minutes,filter,and evaporate the filtrate to dryness.Dry this residue at 105for 1hour:the residue so obtained responds to Identificationtest Aunder Dapsone.

B: Triturate a quantity of finely powdered Tablets,equivalent to about 100mg of dapsone,with 50mLof methanol,and filter.Dilute a portion of the filtrate with methanol to make approximately a 1in 200,000solution:this solution responds to Identificationtest Bunder Dapsone.

Medium: dilute hydrochloric acid (2in 100);1000mL.

Apparatus 1: 100rpm.

Time: 60minutes.

Procedure— Withdraw and filter a portion of the solution under test.Transfer an accurately measured portion of the filtrate,estimated to contain about 0.2mg of dapsone,to a 25-mLvolumetric flask,add 5mLof 1Nsodium hydroxide,dilute with water to volume,and mix.Determine the amount of C12H12N2O2Sdissolved from UVabsorbances at the wavelength of maximum absorbance at about 290nm of the solutions so obtained from the solution under test in comparison with a Standard solution having a known concentration of USP Dapsone RSin the same medium.

Tolerances— Not less than 75%(Q)of the labeled amount of C12H12N2O2Sis dissolved in 60minutes.

Procedure for content uniformity— Transfer 1Tablet to a 100-mLvolumetric flask,add 2.0mLof water,and allow to stand for 30minutes,swirling occasionally.Add about 70mLof methanol,and place the flask in an ultrasonic bath until the specimen is completely dispersed.Add methanol to volume,mix,and centrifuge a portion of the mixture.Quantitatively dilute an accurately measured volume of the clear supernatant with methanol to obtain a solution having a concentration of about 8µg of dapsone per mL.Dissolve an accurately weighed quantity of USP Dapsone RSin methanol to obtain a Standard solution having a known concentration of about 8µg per mL.Concomitantly determine the absorbances of the test solution and the Standard solution in 1-cm cells at the wavelength of maximum absorbance at about 296nm,with a suitable spectrophotometer,using methanol as the blank.Calculate the quantity,in mg,of C12H12N2O2Sin the Tablet taken by the formula: in which Tis the labeled quantity,in mg,of dapsone in the Tablet,Cis the concentration,in µg per mL,of USP Dapsone RSin the Standard solution,Dis the concentration,in µg per mL,of dapsone in the solution from the Tablet,based upon the labeled quantity per Tablet and the extent of dilution,and AUand ASare the absorbances of the solution from the Tablet and the Standard solution,respectively.

Mobile phase,Standard preparation,and Chromatographic system— Prepare as directed in the Assayunder Dapsone.

Assay preparation— Weigh and finely powder not less than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 50mg of dapsone,to a 200-mLvolumetric flask.Add 150mLof methanol,and place the flask in an ultrasonic bath at a temperature of 35for 15minutes,with occasional shaking.Allow to cool to room temperature,add methanol to volume,and mix.Centrifuge a portion of the mixture until clear.Transfer 5.0mLof the clear supernatant to a 50-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.

Procedure— Proceed as directed for Procedurein the Assayunder Dapsone.Calculate the quantity,in mg,of C12H12N2O2Sin the portion of Tablets taken by the formula: