Medium: water; 900 mL.

Apparatus 1: 100 rpm.

Time: 30 minutes.

Procedure— Determine the amount of C16H17N3O5S dissolved from UV absorbances at the wavelength of maximum absorbance at about 263 nm of filtered portions of the solution under test, suitably diluted with water if necessary, in comparison with a Standard solution having a known concentration of USP Cefadroxil RS in the same medium.

Tolerances— Not less than 80% (Q) of the labeled amount of C16H17N3O5S is dissolved in 30 minutes.

pH 5.0 Buffer, Mobile phase, Standard preparation, and Chromatographic system— Proceed as directed in the Assay under Cefadroxil.

Assay preparation— Remove, as completely as possible, the contents of not fewer than 10 Capsules, and weigh. Mix, and transfer an accurately weighed portion of the powder, equivalent to about 200 mg of cefadroxil, to a 200-mL volumetric flask, dilute with pH 5.0 Buffer to volume, and stir by mechanical means for 5 minutes. Use this solution on the day prepared.

Procedure— Proceed as directed for Procedure in the Assay under Cefadroxil. Calculate the quantity, in mg, of C16H17N3O5S in the portion of Capsules contents taken by the formula: in which the terms are as defined therein.