» Cinoxacin Capsules contain not less than 90.0 percent and not more than 110.0 percent of the labeled amount of C12H10N2O5.
Packaging and storage Preserve in well-closed containers.
USP Reference standards 11
Identification Using a portion of Capsule contents to prepare the Test preparation, proceed as directed in the test for Related compounds under Cinoxacin: the RF value of the principal spot obtained from the Test preparation corresponds to that obtained from Solution A.
Medium: pH 6.5 phosphate buffer (see Buffer Solutions in the section Reagents, Indicators, and Solutions); 500 mL for Capsules containing 250 mg or less of cinoxacin; 1000 mL for Capsules containing more than 250 mg of cinoxacin.
Apparatus 1: 100 rpm.
Time: 30 minutes.
Standard preparation Dissolve an accurately weighed quantity of USP Cinoxacin RS in Dissolution Medium to obtain a solution having a known concentration of about 0.35 mg per mL.
Procedure Determine the amount of C12H10N2O5 dissolved from UV absorbances at the wavelength of maximum absorbance at about 270 nm of filtered portions of the solution under test, suitably diluted with 0.1 N sodium hydroxide, in comparison with the Standard preparation, similarly diluted.
Tolerances Not less than 60% (Q) of the labeled amount of C12H10N2O5 is dissolved in 30 minutes.
Uniformity of dosage units 905: meet the requirements.
Assay Transfer the contents of not less than 20 Capsules to a suitable tared container, and weigh. Transfer an accurately weighed portion of the mixed powder, equivalent to about 250 mg of cinoxacin, to a 100-mL volumetric flask. Dilute with 0.1 M sodium borate to volume, and mix. Filter the solution, discarding the first 20 mL of the filtrate, transfer 2.0 mL of the filtrate to a 500-mL volumetric flask, dilute with water to volume, and mix. Concomitantly determine the absorbances of this solution and of a Standard solution of USP Cinoxacin RS in the same medium having a known concentration of about 10 µg per mL, in 1-cm cells at the wavelength of maximum absorbance at about 352 nm, using 2 mL of 0.1 M sodium borate diluted with water to 500 mL as the blank. Calculate the quantity, in mg, of C12H10N2O5 in the portion of Capsules taken by the formula:
25C(AU / AS)in which C is the concentration, in µg per mL, of USP Cinoxacin RS in the Standard solution; and AU and AS are the absorbances of the solution from the Capsules and the Standard solution, respectively.
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USP35NF30 Page 2668