Medium: 0.2MpH7.5phosphate buffer prepared as directed under Buffer Solutionsin the section Reagents,Indicators,and Solutions,except that 0.8Mmonobasic potassium phosphate solution and 0.8Msodium hydroxide solution are used;900mL.

Apparatus 2: 50rpm.

Time: 30minutes.

Procedure— Determine the amount of C15H22O3dissolved from UVabsorbances at the wavelength of maximum absorbance at about 276nm of filtered portions of the solution under test,suitably diluted with 1Nsodium hydroxide,in comparison with a Standard solution obtained as follows.Prepare a standard stock solution of USP Gemfibrozil RShaving a known concentration of about 0.33mg per mLin Medium.[NOTE—Initially dissolve the Reference Standard in an amount of methanol not to exceed 1%of the volume of the standard stock solution.]Dilute the standard stock solution quantitatively with 1Nsodium hydroxide to obtain a Standard solution having a concentration estimated to correspond to that of the filtered and diluted solution under test.

Tolerances— Not less than 80%(Q)of the labeled amount of C15H22O3is dissolved in 30minutes.

Mobile phase,Standard preparation,System suitability preparation,and Chromatographic system— Proceed as directed in the Assayin Gemfibrozil.

Assay preparation— Weigh and finely powder not less than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 100mg of gemfibrozil,to a 100-mLvolumetric flask,add about 80mLof methanol,and shake to dissolve.Dilute with methanol to volume,mix,and filter.Transfer 5.0mLof this clear solution to a 25-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.

Procedure— Proceed as directed for Procedurein the Assayin Gemfibrozil.Calculate the quantity,in mg,of C15H22O3in the portion of Tablets taken by the formula: in which the terms are as defined therein.