Benzenesulfonamide, 4-amino-
N-(5-methyl-1,3,4-thiadiazol-2-yl)-.
N1-(5-Methyl-1,3,4-thiadiazol-2-yl)sulfanilamide
[
144-82-1].
Packaging and storage—
Preserve in well-closed, light-resistant containers.
Clarity and color of solution—
Dissolve 1.0 g in 20 mL of water and 5 mL of 1 N sodium hydroxide: the solution is clear and not more than pale yellow.
Identification—
B:
To about 0.1 g add 5 mL of 3 N hydrochloric acid, and boil gently for about 5 minutes. Cool in an ice bath, then add 4 mL of a sodium nitrite solution (1 in 100), add water to make 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.
C:
To about 20 mg suspended in 5 mL of water add, dropwise, 1 N sodium hydroxide until dissolved, then add 2 or 3 drops of
cupric sulfate TS: a light green precipitate is formed, and it does not change on standing.
D:
The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that of the Standard preparation as obtained in the Assay.
Acidity—
Digest 2.0 g with 100 mL of water at about 70
for 5 minutes, cool immediately to about 20
, 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 0.50 mL is required for neutralization. Save the remainder of the filtrate for the tests for
Chloride and for
Sulfate.
Chloride 
221
—
A 25.0-mL portion of the filtrate prepared 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 25.0-mL portion of the filtrate prepared in the test for
Acidity shows no more sulfate than corresponds to 0.20 mL of 0.020 N sulfuric acid (0.04%).
Heavy metals, Method II 231:
0.002%.
Assay—
Mobile phase—
Prepare a filtered and degassed mixture of water, methanol, and glacial acetic acid (69:30:1). Make adjustments if necessary (see
System Suitability under
Chromatography 621).
Standard preparation—
Dissolve an accurately weighed quantity of
USP Sulfamethizole RS in methanol to obtain a solution having a known concentration of about 0.4 mg per mL. Quantitatively dilute a volume of this solution with
Mobile phase to obtain the
Standard preparation having a known concentration of about 8 µg per mL.
Assay preparation—
Transfer about 20 mg of sulfamethizole, accurately weighed, to a 50-mL volumetric flask, dilute with methanol to volume, and mix. Quantitatively dilute a volume of this solution with Mobile phase to obtain the Assay preparation having a concentration of about 8 µg per mL.
Chromatographic system
(see
Chromatography 621)—The liquid chromatograph is equipped with a 254-nm detector and a 3.9-mm × 30-cm column that contains 10-µm packing L1. The flow rate is about 1.0 mL per minute. Chromatograph the
Standard preparation, and record the peak responses as directed for
Procedure: the column efficiency determined from the analyte peak is not less than 2000 theoretical plates, the tailing factor for the analyte peak is not more than 2.0, and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure—
Separately inject equal volumes (about 50 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
9H
10N
4O
2S
2 in the portion of Sulfamethizole taken by the formula:
2.5C(rU / rS),
in which
C is the concentration, in µg per mL, of
USP Sulfamethizole RS in the
Standard preparation, and
rU and
rS are the peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.
;)