Assay—
Transfer an accurately measured volume of Oral Suspension, equivalent to about 160 mg of furazolidone, to a suitable flask. Add 5 mL of water, and mix. Transfer the mixture with the aid of dimethylformamide to a 1000-mL volumetric flask. Add about 500 mL of dimethylformamide, shake by mechanical means for 10 minutes, dilute with dimethylformamide to volume, and mix. Transfer 5.0 mL of this solution to a 100-mL volumetric flask, dilute with water to volume, and mix (assay solution). Similarly, dissolve a suitable quantity of
USP Furazolidone RS, accurately weighed, in dimethylformamide to obtain a Standard stock solution having a known concentration of about 160 µg per mL. Transfer 5.0 mL of this stock solution to a 100-mL volumetric flask, dilute with water to volume, and mix (Standard solution). Concomitantly determine the absorbances of the assay solution and the Standard solution at the wavelength of maximum absorbance at about 367 nm, with a suitable spectrophotometer, using dimethylformamide solution (1 in 20) as the blank. Calculate the quantity, in mg, of furazolidone (C
8H
7N
3O
5) in each mL of the Oral Suspension taken by the formula:
20(C / V)(AU / AS),
in which
C is the concentration, in µg per mL, of
USP Furazolidone RS in the Standard solution;
V is the volume, in mL, of Oral Suspension taken; and
AU and
AS are the absorbances of the assay solution and the Standard solution, respectively.
791
:
between 6.0 and 8.5.