Packaging and storage
Preserve in tight, light-resistant containers.
Identification
B:
Ultraviolet Absorption
197U
Solution:
10 µg per mL.
Medium:
alcohol.
Absorptivities at 290 nm, calculated on the dried basis, do not differ by more than 3.0%.
Ordinary impurities
466
Test solution:
methanol.
Standard solution:
methanol.
Eluant:
a mixture of toluene and acetone (1:1).
Visualization:
1.
Organic volatile impurities, Method IV
467
:
meets the requirements.
Other requirements
It meets the requirements for Residue on ignition, Selenium, and Heavy metals under Sulfisoxazole.
Assay
Transfer about 1 g of Sulfisoxazole Acetyl, accurately weighed, to a 250-mL beaker. Add 15 mL of glacial acetic acid, swirl to dissolve, then add 25 mL of hydrochloric acid and 80 mL of water. Proceed as directed under
Nitrite Titration
451
, beginning with Cool to about 15

. Each mL of 0.1
M sodium nitrite is equivalent to 30.94 mg of C
13H
15N
3O
4S.