Medium: pH 7.5 phosphate buffer (see Buffer Solutions in the section Reagents, Indicators, and Solutions); 900 mL.

Apparatus 1: 100 rpm.

Time: 45 minutes.

Procedure— Determine the amount of C7H7NO3 dissolved, employing the procedure set forth in the Assay, making any necessary modifications.

Tolerances— Not less than 75% (Q) of the labeled amount of C7H7NO3 is dissolved in 45 minutes.

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

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

Test solution— 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 aminosalicylic acid 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 solution; W is the quantity of aminosalicylic acid, 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 solution and the Standard solution; 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 500 mg of aminosalicylic acid, 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 100-mL low-actinic 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 aminosalicylic acid (C7H7NO3) in the portion of Tablets taken by the formula: in which 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.