USP Monographs: Sulfathiazole

Sulfathiazole

C9H9N3O2S2

255.32

Benzenesulfonamide, 4-amino-N-2-thiazolyl-.
N1-2-Thiazolylsulfanilamide

[72-14-0].

» Sulfathiazole contains not less than 99.0 percent and not more than 100.5 percent of C9H9N3O2S2, calculated on the dried basis.

Packaging and storage— Preserve in well-closed, light-resistant containers.

USP Reference standards

— USP Sulfathiazole RS.

Identification—

A: Infrared Absorption

197K

B: To 100 mg add 5 mL of 3 N hydrochloric acid, and boil gently for about 5 minutes. Cool in an ice bath, add 4 mL of sodium nitrite solution (1 in 100), dilute with water to 10 mL, and place the mixture in an ice bath for 10 minutes. To 5 mL of the cooled mixture add a solution of 50 mg of 2-naphthol in 2 mL of sodium hydroxide solution (1 in 10): an orange-red precipitate is formed, and it darkens on standing.

Melting range, Class I

741

: between 200

and 204

Acidity— Digest 2 g with 100 mL of water at about 70

for 5 minutes, cool at once to about 20

, and filter. Titrate 25 mL of the filtrate with 0.10 N sodium hydroxide, using 2 drops of phenolphthalein TS as the indicator: not more than 0.5 mL is required to produce a pink color. (Retain the remainder of the filtrate for the tests for Chloride

221

and for Sulfate

221

Loss on drying

731

— Dry it at 105

for 2 hours: it loses not more than 0.5% of its weight.

Residue on ignition

281

: not more than 0.1%.

Chloride

221

— A 25-mL portion of the filtrate prepared as directed in the test for Acidity shows no more chloride than corresponds to 0.10 mL of 0.020 N hydrochloric acid (0.014%).

Sulfate

221

— A 25-mL portion of the filtrate prepared as directed in the test for Acidity shows no more sulfate than corresponds to 0.2 mL of 0.02 N sulfuric acid (0.04%).

Heavy metals, Method II

231

: 0.002%.

Ordinary impurities

466

—

Test solution: methanol.

Standard solution: methanol.

Eluant: a mixture of 1-propanol and 1 N ammonium hydroxide (22:3).

Visualization: 1.

Residual solvents

467