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.
Dissolution 
711
—
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.
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 C
12H
10N
2O
5 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.
