A: Place about 1g in a small,round-bottom flask,and add 10mLof acetic anhydride.Heat the flask on a steam bath for 30minutes,add 40mLof 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 105for 1hour:the diacetyl derivative so obtained melts between 191and 197.

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

Medium: water;900mL.

Apparatus 1: 100rpm.

Time: 45minutes.

Procedure— Determine the amount of C7H6NNaO3·2H2Odissolved,employing the procedure set forth in the Assay,making any necessary modifications.

Tolerances— Not less than 75%(Q)of the labeled amount of C7H6NNaO3·2H2Ois dissolved in 45minutes.

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

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

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

Procedure— Proceed as directed for Procedurein the test for Limit of m-aminophenolunder 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 Cis the concentration,in µg per mL,of USPm-Aminophenol RSin the Standard preparation;Wis the quantity of aminosalicylate sodium,in mg,in the portion of Tablets taken,as determined in the Assay;and RUand RSare the ratios of the response of the m-aminophenol peak to the response of the sulfanilamide peak obtained from the Test preparationand the Standard preparation,respectively:not more than 1.0%of m-aminophenol is found.

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

Assay preparation— Weigh and finely powder not fewer than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 690mg of aminosalicylate sodium,to a 100-mLlow-actinic volumetric flask.Add 50mLof Mobile phase,and shake for about 5minutes.Dilute with Mobile phaseto volume,and mix.Filter,and transfer 10.0mLof the clear filtrate to a low-actinic,100-mLvolumetric flask containing 10.0mLof Internal standard solution,dilute with Mobile phaseto volume,and mix.

Procedure— Proceed as directed for Procedurein the Assayunder Aminosalicylic Acid.Calculate the quantity,in mg,of C7H6NNaO3·2H2Oin the portion of Tablets taken by the formula: in which 211.15and 153.14are the molecular weights of aminosalicylate sodium dihydrate and aminosalicylic acid,respectively;Cis the concentration,in mg per mL,of USP Aminosalicylic Acid RSin the Standard preparation;and RUand RSare the ratios of the response of the aminosalicylic acid peak to the response of the acetaminophen peak obtained from the Assay preparationand the Standard preparation,respectively.