Packaging and storage—
Preserve in well-closed, light-resistant containers.
Clarity and color of solution—
Dissolve 1 g in a mixture of 20 mL of water and 5 mL of 1 N sodium hydroxide. The solution is clear and not more deeply colored than pale yellow.
Identification—
B:
Carefully melt about 50 mg in a small test tube: a reddish brown color develops. The fumes evolved during the decomposition do not discolor moistened lead acetate test paper (distinction from sulfathiazole).
C:
Gently heat about 1 g in a small test tube until a sublimate is formed. Collect a few mg of the sublimate with a glass rod, and mix in a test tube with 1 mL of a 1 in 20 solution of resorcinol in alcohol. Add 1 mL of sulfuric acid, and mix by shaking: a deep red color appears at once. Cautiously dilute the mixture with 25 mL of ice-cold water, and add an excess of 6 N ammonium hydroxide: a blue or reddish blue color is produced.
Acidity—
Digest 2.00 g with 100 mL of water at about 70
for 5 minutes. Cool at once to room temperature, and filter. To 25.0 mL of the filtrate add 2 drops of phenolphthalein TS, and titrate with 0.10 N sodium hydroxide: not more than 0.20 mL is required to produce a pink color.
Heavy metals, Method II 
231
:
0.002%.
Ordinary impurities 466—
Test solution:
8.3 mg per mL, in a mixture of toluene and dimethylformamide (2:1).
Standard solutions:
0.008, 0.041, 0.08, and 0.17 mg per mL, in a mixture of toluene and dimethylformamide (2:1).
Eluant:
a mixture of chloroform, methanol, and ammonium hydroxide (30:12:1).
Visualization:
11.
Assay—
Mobile phase—
Prepare a suitable degassed solution of water, acetonitrile, and glacial acetic acid (87:12:1).
Standard preparation—
Dissolve an accurately weighed quantity of
USP Sulfadiazine RS in 0.025 N sodium hydroxide to obtain a solution having a known concentration of about 1 mg per mL.
Assay preparation—
Transfer about 100 mg of Sulfadiazine, accurately weighed, to a 100-mL volumetric flask, add 0.025 N sodium hydroxide to volume, and mix.
Chromatographic system
(see
Chromatography 621)—The liquid chromatograph is equipped with a 254-nm detector and a 4-mm × 30-cm column that contains packing L1. The flow rate is about 2 mL per minute. Chromatograph five replicate injections of the
Standard preparation, and record the peak responses as directed for
Procedure: the relative standard deviation is not more than 2.0%, and the tailing factor for sulfadiazine is not more than 1.5.
Procedure—
Separately inject equal volumes (about 10 µL) of the
Standard preparation and the
Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C
10H
10N
4O
2S in the portion of Sulfadiazine taken by the formula:
100C(rU / rS),
in which
C is the concentration, in mg per mL, of
USP Sulfadiazine RS in the
Standard preparation; and
rU and
rS are the peak responses for sulfadiazine obtained from the
Assay preparation and the
Standard preparation, respectively.
;)
