Identification—
A:
Dissolve about 1 g in 25 mL of water, adjust with 6 N acetic acid to a pH of between 4 and 5, and filter. Wash the precipitate with water, and dry at 105
for 2 hours: the sulfacetamide so obtained melts between 180
and 184
.
B:
Place about 500 mg of the sulfacetamide obtained in
Identification test
A in a test tube, and heat gently until it boils: an oily liquid, which has the characteristic odor of acetamide, condenses on the walls of the test tube (
distinction from the sublimates of sulfadiazine,
sulfamerazine,
and sulfamethazine,
which are solids at room temperature).
C:
The filtrate obtained in
Identification test
A responds to the tests for
Sodium 
191
.
D:
Dissolve about 100 mg in 5 mL of water, and add 5 drops of
cupric sulfate TS: a light bluish green precipitate is formed, and it remains unchanged on standing.
E:
Dissolve about 500 mg in 10 mL of dilute hydrochloric acid (1 in 10). To about one-half of the solution add 2 mL of trinitrophenol TS: a very heavy flocculent or almost gelatinous precipitate is formed. To the remainder of the solution add 3 drops of formaldehyde TS: a white precipitate is formed, and it changes to orange on standing (distinction from sulfamethoxypyridazine).
Heavy metals—
Dissolve 1.0 g in 25 mL of water, and add 5 drops of freshly prepared
sodium sulfide TS: any color produced is not darker than that of a control made with 25 mL of water, 2.0 mL of
Standard Lead Solution (see
Heavy Metals 231), and 5 drops of
sodium sulfide TS (0.002%).
Ordinary impurities 466—
Test solution:
methanol.
Standard solution:
methanol.
Eluant:
a mixture of ethyl acetate, methanol, and ammonium hydroxide (17:6:5).
Visualization:
1.
Sulfacetamide Sodium contains not less than 99.0 percent and not more than 100.5 percent of C8H9N2NaO3S, calculated on the anhydrous basis.