» Sulfisoxazole Tablets contain not less than 95.0 percent and not more than 105.0 percent of the labeled amount of C11H13N3O3S.
Packaging and storage Preserve in well-closed, light-resistant containers.
Identification Extract a quantity of powdered Tablets, equivalent to about 1 g of sulfisoxazole, with 50 mL of alcohol by boiling on a steam bath for 3 minutes, then immediately filter into a beaker. Allow to stand until a quantity of fine, needle-like crystals form. Cool, filter off the crystals, recrystallize from a small volume of alcohol, and dry at 105: the crystals respond to Identification test A under Sulfisoxazole.
Medium: dilute hydrochloric acid (1 in 12.5); 900 mL.
Apparatus 1: 100 rpm.
Time: 30 minutes.
Procedure [noteBecause of the pH-dependent nature of the UV absorption spectrum, prepare the standard and specimen solutions in the same strength of acid at approximately equal concentrations.] Determine the amount of C11H13N3O3S dissolved from UV absorbances at the wavelength of maximum absorbance at about 267 nm of filtered portions of the solution under test, suitably diluted with water, if necessary, in comparison with a Standard solution having a known concentration of USP Sulfisoxazole RS in the same medium.
Tolerances Not less than 70% (Q) of the labeled amount of C11H13N3O3S is dissolved in 30 minutes.
Uniformity of dosage units 905: meet the requirements.
Auxiliary Information Please check for your question in the FAQs before contacting USP.
USP32NF27 Page 3636