C18H14N4O5S 398.39

Benzoic acid,2-hydroxy-5-[[4-[(2-pyridinylamino)sulfonyl]phenyl]azo]-.
5-[[p-(2-Pyridylsulfamoyl)phenyl]azo]salicylic acid [599-79-1].

Packaging and storage— Preserve in tight,light-resistant containers.

USP Reference standards á11ñ— USP Sulfasalazine RS.

Identification—

Loss on drying á731ñ— Dry it at 105for 2hours:it loses not more than 1.0%of its weight.

Residue on ignition á281ñ: not more than 0.5%.

Chloride á221ñ— Digest 2.0g of Sulfasalazine with 100mLof water at 70for 5minutes.Cool immediately to room temperature,and filter.Transfer a 25-mLportion of the filtrate to a 50-mLbeaker (retain the remainder of this filtrate for the Sulfate test),add 1mLof nitric acid,mix,and allow to stand for 5minutes.Filter through a fine texture,retentive filter paper (Whatman No.42,or equivalent):the filtrate shows no more chloride than corresponds to 0.10mLof 0.020Nhydrochloric acid (0.014%).

Sulfate á221ñ— Transfer a 25-mLportion of the filtrate from the Chloride testto a 50-mLbeaker.Add 1mLof 3Nhydrochloric acid,mix,and allow to stand for 5minutes.Filter through a fine texture,retentive filter paper (Whatman No.42,or equivalent):the filtrate shows no more sulfate than corresponds to 0.20mLof 0.020Nsulfuric acid (0.04%).

Heavy metals,Method IIá231ñ: 0.002%.

Chromatographic purity— Prepare a solution of Sulfasalazine in a mixture of alcohol and 2Mammonium hydroxide (4:1)having a concentration of 10mg per mL.Similarly prepare a Standard solution of USP Sulfasalazine RSin the same medium having a concentration of 10mg per mL.Dilute aliquots of the Standard solution quantitatively and stepwise with the same medium to obtain solutions having concentrations of 200,150,100,and 20µg per mL,corresponding to 2.0%,1.5%,1.0%,and 0.2%,respectively (Standard dilutions A,B,C,and D).Separately apply 10-µLeach of the test solution,the Standard solution,and the Standard dilutionsto a suitable thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel mixture.Allow the spots to dry,and develop the chromatogram in an unequilibrated chamber with a solvent system consisting of a mixture of chloroform,acetone,and formic acid (60:30:5)until the solvent front has moved about three-fourths of the length of the plate.Remove the plate from the chamber,mark the solvent front,dry with the aid of a current of hot air,and examine the plate under short-wavelength UVlight:the RFvalue of the principal spot obtained from the test solution corresponds to that obtained from the Standard solution,and no spots,other than the principal spot,in the chromatogram of the test solution are larger or more intense than the principal spot obtained from Standard dilution A(2%),and the sum of the intensities of any secondary spots detected does not exceed 4%.

Organic volatile impurities,Method Vá467ñ: meets the requirements.

Assay— Transfer about 150mg of Sulfasalazine,accurately weighed,to a 100-mLvolumetric flask.Dissolve in 0.1Nsodium hydroxide,dilute with 0.1Nsodium hydroxide to volume,and mix.Transfer 5.0mLof this solution to a 1000-mLvolumetric flask containing about 750mLof water,mix,add 20.0mLof 0.1Nacetic acid,dilute with water to volume,and mix.Concomitantly determine the absorbances of this solution and of a Standard solution of USP Sulfasalazine RSin the same medium having a known concentration of about 7.5µg per mL,at the wavelength of maximum absorbance at about 359nm,using water as the blank.Calculate the quantity,in mg,of C18H14N4O5Sin the Sulfasalazine taken by the formula: in which Cis the concentration,in µg per mL,of USP Sulfasalazine RSin the Standard solution,and AUand ASare the absorbances obtained from the assay solution and the Standard solution,respectively.

Expert Committee:(PA7)Pharmaceutical Analysis 7

USP28–NF23Page 1833

Phone Number:1-301-816-8394