A: Place a portion of Capsule contents,equivalent to about 250mg of mefenamic acid,in a 250-mLvolumetric flask,add about 100mLof a mixture of chloroform and methanol (3:1),and shake vigorously.Dilute with a mixture of chloroform and methanol (3:1)to volume,mix,and filter:the filtrate so obtained responds to the Thin-layer Chromatographic Identification Test á201ñ,a solvent system consisting of a mixture of chloroform,ethyl acetate,and glacial acetic acid (75:25:1)and the Ordinary Impurities á466ñvisualization technique 17being used.

B: The retention time of the major peak in the chromatogram of the Assay preparationcorresponds to that of the Standard preparation,obtained as directed in the Assay.

0.05M Tris buffer— Dissolve 60.5g of tris(hydroxymethyl)aminomethane in 6Lof water,and dilute with water to 10L.Adjust with phosphoric acid to a pHof 9.0±0.05.To a second container,transfer about 6liters of this solution,add 100g of sodium lauryl sulfate,and mix to dissolve the solid material.Transfer this solution back into the first container,and mix.

Medium:0.05M Tris buffer; 900mL.

Apparatus 1: 100rpm.

Time: 45minutes.

Procedure— Determine the amount of C15H15NO2dissolved,employing the procedure set forth in the Assay,making any necessary volumetric adjustments.

Tolerances— Not less than 75%(Q)of the labeled amount of C15H15NO2is dissolved in 45minutes.

Mobile phase ,Standard preparation,and Chromatographic system—Proceed as directed in the Assayunder Mefenamic Acid.

Assay preparation— Remove,as completely as possible,the contents of not fewer than 20Capsules.Weigh the contents,and determine the average weight per capsule.Mix the combined contents,and transfer an accurately weighed quantity of the powder,equivalent to about 100mg of mefenamic acid,to a 500-mLvolumetric flask.Add 10.0mLof tetrahydrofuran,and sonicate for about 5minutes with occasional mixing.Dilute with Mobile phaseto volume,mix,and filter.

Procedure— Proceed as directed for Procedurein the Assayunder Mefenamic Acid.Calculate the quantity,in mg,of C15H15NO2in the portion of Capsules taken by the formula: in which the terms are as defined therein.