A: 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 well with water, and dry at 105 for 1 hour: the diacetyl derivative so obtained melts between 191 and 197.

B: Shake 0.1 g with 10 mL of water, and filter. To 5 mL of the filtrate add 1 drop of ferric chloride TS: a violet color is produced.

Medium: water; 900 mL.

Apparatus 1: 100 rpm.

Time: 45 minutes.

Procedure— Determine the amount of C7H6NNaO3·2H2O dissolved, employing the procedure set forth in the Assay, making any necessary modifications.

Tolerances— Not less than 75% (Q) of the labeled amount of C7H6NNaO3·2H2O is dissolved in 45 minutes.

Mobile phase and Internal standard solution—Prepare as directed in the Assay under Aminosalicylic Acid.

Standard preparation and Chromatographic system—Prepare as directed in the test for Limit of m-aminophenol under Aminosalicylic Acid.

Test preparation— Use the Assay preparation, prepared as directed in the Assay.

Procedure— Proceed as directed for Procedure in the test for Limit of m-aminophenol under Aminosalicylic Acid. Calculate the percentage of m-aminophenol, in relation to the quantity of aminosalicylate sodium in the portion of Tablets taken by the formula: 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 Tablets 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 1.0% of m-aminophenol is found.

(Official January 1, 2007)

Mobile phase, Internal standard solution, Standard preparation, and Chromatographic system— Prepare as directed in the Assay under Aminosalicylic Acid.

Assay preparation— Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 690 mg of aminosalicylate sodium, to a 100-mL low-actinic volumetric flask. Add 50 mL of Mobile phase, and shake for about 5 minutes. Dilute with Mobile phase to volume, and mix. Filter, and transfer 10.0 mL of the clear filtrate to a low-actinic, 100-mL volumetric flask containing 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, in mg, of C7H6NNaO3·2H2O in the portion of Tablets taken by the formula: in which 211.15 and 153.14 are the molecular weights of aminosalicylate sodium dihydrate 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.