Medium: 0.12 N hydrochloric acid; 900 mL.

Apparatus 2: 75 rpm.

Time: 60 minutes.

Procedure— Determine the amount of C16H19N3O4S dissolved from UV absorbances at the wavelength of maximum absorbance at about 255 nm of filtered portions of the solution under test, suitably diluted with Dissolution Medium, in comparison with a Standard solution having a known concentration of USP Cephradine RS in the same medium.

Tolerances— Not less than 85% (Q) of the labeled amount of C16H19N3O4S is dissolved in 60 minutes.

Mobile phase, Standard preparation, Resolution solution, and Chromatographic system— Proceed as directed in the Assay under Cephradine.

Assay preparation— Place not less than 5 Tablets in a high-speed glass blender jar containing an accurately measured volume of water, sufficient to yield a concentration of not less than 5 mg of cephradine per mL, and blend for 4 ± 1 minutes. Dilute an accurately measured volume of this stock solution quantitatively and stepwise with Mobile phase to obtain an Assay preparation containing about 0.5 mg of cephradine per mL.

Procedure— Separately inject equal volumes (about 10 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of cephradine (sum of cephradine and cephalexin) in each Tablet taken by the formula: in which C is the concentration, in mg per mL, of USP Cephradine RS in the Standard preparation; P is the designated potency, in µg per mg, of USP Cephradine RS; L is the labeled quantity, in mg of cephradine, in each Tablet; D is the concentration, in mg of cephradine per mL, of the Assay preparation, based on the labeled quantity per Tablet, the number of Tablets taken, and the extent of dilution; and rU and rS are the sums of the cephradine and cephalexin peak responses obtained from the Assay preparation and the Standard preparation, respectively.