Packaging and storage—
Preserve in well-closed, light-resistant containers.
Identification—
Triturate a quantity of finely powdered Tablets, equivalent to about 500 mg of sulfapyridine, with 5 mL of chloroform, and transfer to a small filter. Wash with another 5-mL portion of chloroform, and discard the filtrate. Triturate the residue with 10 mL of 6 N ammonium hydroxide for 5 minutes, add 10 mL of water, and filter. Warm the filtrate until most of the ammonia is expelled, cool, and add 6 N acetic acid until the reaction is distinctly acid: a precipitate of sulfapyridine is formed. Collect the precipitate on a filter, wash it well with cold water, and dry at 105
for 1 hour: the sulfapyridine so obtained melts between 189
and 192
as determined by the method for
Class Ia under
Melting Range or Temperature 
741
, and responds to the
Identification tests under
Sulfapyridine.
Dissolution 711—
Medium:
0.01 N hydrochloric acid; 900 mL.
Apparatus 2:
50 rpm.
Time:
60 minutes.
Procedure—
Determine the amount of C
11H
11N
3O
2S dissolved by employing UV absorption at the wavelength of maximum absorbance at about 254 nm on filtered portions of the solution under test, suitably diluted with 0.01 N sodium hydroxide, in comparison with a Standard solution having a known concentration of
USP Sulfapyridine RS in the same media.
Tolerances—
Not less than 70% (Q) of the labeled amount of C11H11N3O2S is dissolved in 60 minutes.
Assay—
Weigh and finely powder not less than 20 Tablets. Weigh accurately a portion of the powder, equivalent to about 500 mg of sulfapyridine, and proceed as directed under
Nitrite Titration 451, beginning with “and transfer to a suitable open vessel.” Each mL of 0.1
M sodium nitrite is equivalent to 24.93 mg of C
11H
11N
3O
2S.
