FORCEPHALEXIN —

Medium: water;900mL.

Apparatus 1— Use 40-mesh cloth and 100rpm.

Time: 30minutes.

Procedure— Determine the amount of C16H17N3O4Sdissolved from the UVabsorbances at the wavelength of maximum absorbance at about 262nm of a filtered portion of the solution under test,suitably diluted with Dissolution Medium,if necessary,to a concentration of about 20µg per mL,in comparison with a Standard solution having a known concentration of USP Cephalexin RSin the same medium.

Tolerances— Not less than 80%(Q)of the labeled amount of C16H17N3O4Sis dissolved in 30minutes.

FORCEPHALEXIN HYDROCHLORIDE —

Medium and Procedure—Proceed as directed under For cephalexin.

Apparatus 1— Use 10-mesh cloth and 150rpm.

Time: 45minutes.

Tolerances— Not less than 75%(Q)of the labeled amount of C16H17N3O4Sis dissolved in 45minutes.

Mobile phase ,Internal standard solution,Standard preparation,and Chromatographic system—Prepare as directed in the Assayunder Cephalexin.

Assay preparation— Weigh and finely powder not less than 20Tablets.Transfer an accurately weighed quantity of the powder,equivalent to about 500mg of cephalexin,to a 500-mLvolumetric flask,add water to volume,and mix.Sonicate,if necessary,to assure complete dissolution of the cephalexin.Filter,if necessary,to obtain a clear solution.Transfer 10.0mLof this solution to a 50-mL,glass-stoppered flask,add 15.0mLof Internal standard solution,mix,and filter.

Procedure— Proceed as directed for Procedurein the Assayunder Cephalexin.Calculate the quantity,in mg,of C16H17N3O4Sin the portion of Tablets taken by the formula: in which the terms are as defined therein.