Packaging and storage—
Preserve in well-closed, light-resistant containers.
Clarity and color of solution—
Dissolve 2.0 g in 15 mL of 1 N sodium hydroxide, with warming: a colorless to pale yellow solution having not more than a slight turbidity is produced.
Identification—
B:
To about 100 mg, suspended in 2 mL of water, add 100 mg of sodium bicarbonate: it dissolves with effervescence (distinction from sulfanilamide, sulfapyridine, sulfathiazole, sulfadiazine, and sulfaguanidine).
Selenium 
291
:
0.001%, a 300-mg test specimen and 3 mL of
Stock Solution being used.
Heavy metals, Method II 231:
0.002%.
Ordinary impurities 466—
Test solution:
methanol.
Standard solution:
methanol.
Eluant:
a mixture of chloroform, methanol, and glacial acetic acid (90:5:5).
Visualization:
1.
Assay—
Transfer about 800 mg of Sulfabenzamide, accurately weighed, to a 125-mL conical flask, and dissolve in 25 mL of dimethylformamide. Add 3 drops of
thymol blue TS (prepared with methanol), and titrate with 0.1 N sodium methoxide VS to a blue endpoint. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N sodium methoxide is equivalent to 27.63 mg of C
13H
12N
2O
3S.
;)
for 2 hours: it loses not more than 0.5% of its weight.