Medium: 0.1 N hydrochloric acid; 900 mL.

Apparatus 1 (10-mesh basket): 100 rpm.

Times: 30, 60, and 240 minutes.

Procedure— Quantitatively dilute filtered portions of the solution under test with 0.1 N hydrochloric acid to obtain a test solution having a concentration of cefaclor (C15H14ClN3O4S) estimated to be about 25 µg per mL. Determine the amount of cefaclor (C15H14ClN3O4S) dissolved by employing UV absorption at the wavelength of maximum absorbance at about 265 nm, in comparison with a Standard solution having a similar, known concentration of USP Cefaclor RS in the same Medium.

Tolerances— The percentages of the labeled amount of cefaclor (C15H14ClN3O4S) dissolved at the times specified conform to Acceptance Table 2.

Solvent, Blank solution, Solution A, Solution B, Mobile phase, Standard solution, System suitability solution, and Chromatographic system— Proceed as directed for Related compounds under Cefaclor.

Test solution— Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the composite, equivalent to about 50 mg of cefaclor, to a 10-mL volumetric flask. Dissolve in Solvent, using brief sonication, if necessary, to achieve dissolution. Avoid heating. Dilute with Solvent to volume, mix, and filter. Use this Test solution within 3 hours if stored at room temperature, or within 20 hours when stored under refrigeration.

Procedure— Separately inject equal volumes (about 20 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the peak area responses for all the peaks. Calculate the mg of each related compound in the portion of Tablets taken by the formula: in which the terms are as defined for Related compounds under Cefaclor. Not more than 0.6% of any individual cefaclor-related compound is found; and the sum of all cefaclor-related compounds found is not more than 2.0%, not including the contribution of any peak that gives a result of less than 0.1%.

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

Assay preparation— Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 75 mg of cefaclor, to a 250-mL volumetric flask, dilute with Mobile phase to volume, and mix. Sonicate, if necessary, to dissolve the cefaclor. Filter to obtain a clear solution.

Procedure— Proceed as directed in the Assay under Cefaclor. Calculate the quantity, in mg, of cefaclor (C15H14ClN3O4S) in the portion of Tablets taken by the formula: in which the terms are as defined therein.