Packaging and storage—
Preserve in tight, light-resistant containers, protected from excessive heat.
Clarity and color of solution—
One g dissolves in 10 mL of water to give a clear solution that has not more than a faint yellow color. One g dissolves in a freshly prepared mixture of 5 mL of nitric acid and 45 mL of water to give a clear solution that has not more than a slight color.
Identification—
A:
Dissolve 250 mg in 3 mL of 1 N sodium hydroxide, transfer to a 500-mL volumetric flask, dilute with water to volume, and mix. Transfer a 5-mL aliquot to a 250-mL volumetric flask containing 12.5 mL of pH 7 phosphate buffer (see under Buffer Solutions in the section Reagents, Indicators, and Solutions), dilute with water to volume, and mix. This solution, when compared in a suitable spectrophotometer against a blank of the same buffer in the same concentration, exhibits absorbance maxima at 265 ± 2 nm and 299 ± 2 nm, and the ratio A265/A299 is between 1.50 and 1.56.
B:
Place about 1 g in a small, round-bottom flask, and add 10 mL of acetic anhydride. Heat the flask on a steam bath for 30 minutes, add 40 mL of water, mix, filter, cool, and allow to stand until the diacetyl derivative has crystallized. Collect the precipitate on a filter, wash with water, and dry at 105
for 1 hour: the diacetyl derivative so obtained melts between 191
and 197
.
C:
Dissolve 50 mg in 5 mL of water, add 1 mL of 3 N hydrochloric acid, and filter if necessary. To the filtrate add 1 drop of
ferric chloride TS: a violet color is produced.
D:
A solution of it responds to the tests for
Sodium 
191
.
pH 791:
between 6.5 and 8.5, in a solution (1 in 50).
Chloride 221—
Dissolve 0.50 g in a mixture of 5 mL of nitric acid and 15 mL of water: the solution shows no more chloride than corresponds to 0.30 mL of 0.020 N hydrochloric acid (0.042%).
Heavy metals, Method II 231:
0.003%.
Limit of m-aminophenol—
Test preparation—
Use the
Assay preparation, prepared as directed in the
Assay.
Procedure—
Separately inject equal volumes (about 20 µL) of the
Standard preparation and the
Test preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. The relative retention times are about 0.66 for sulfanilamide and 1.0 for
m-aminophenol. Calculate the percentage of
m-aminophenol, in relation to the quantity of aminosalicylate sodium in the portion of Aminosalicylate Sodium taken by the formula:
10(C / W)(RU / RS),
in which
C is the concentration, in µg per mL, of USP
m-Aminophenol RS in the
Standard preparation; W is the quantity of aminosalicylate sodium, in mg, in the portion of Aminosalicylate Sodium taken, as determined in the
Assay; and
RU and
RS are the ratios of the response of the
m-aminophenol peak to the response of the sulfanilamide peak obtained from the
Test preparation and the
Standard preparation, respectively: not more than 0.25% of
m-aminophenol is found.
Hydrogen sulfide, sulfur dioxide, and amyl alcohol—
Dissolve about 500 mg in 5 mL of 1 N sodium hydroxide, add 6 mL of 3 N hydrochloric acid, and stir vigorously: no odor of hydrogen sulfide or sulfur dioxide is perceptible, and not more than a faint odor of amyl alcohols is perceptible. A piece of moistened lead acetate test paper held over the mixture does not become discolored.
Organic volatile impurities, Method I 467:
meets the requirements.
Assay—
Mobile phase, Internal standard solution, Standard preparation, and Chromatographic system—
Prepare as directed in the
Assay under
Aminosalicylic Acid.
Assay preparation—
Transfer about 69 mg of Aminosalicylate Sodium, accurately weighed, to a 100-mL low-actinic volumetric flask, add 50 mL of Mobile phase, and swirl to dissolve. Add 10.0 mL of Internal standard solution, dilute with Mobile phase to volume, and mix.
Procedure—
Proceed as directed for
Procedure in the
Assay under
Aminosalicylic Acid. Calculate the quantity of C
7H
6NNaO
3, in mg, in the Aminosalicylate Sodium taken by the formula:
(175.12 / 153.14)(100C)(RU / RS),
in which 175.12 and 153.14 are the molecular weights of anhydrous aminosalicylate sodium and aminosalicylic acid, respectively;
C is the concentration, in mg per mL, of
USP Aminosalicylic Acid RS in the
Standard preparation; and
RU and
RS are the ratios of the response of the aminosalicylic acid peak to the response of the acetaminophen peak obtained from the
Assay preparation and the
Standard preparation; respectively.
