Sulfasalazine
398.39Benzoic acid, 2-hydroxy-5-[[4-[(2-pyridinylamino)sulfonyl]phenyl]azo]-.
5-[[p-(2-Pyridylsulfamoyl)phenyl]azo]salicylic acid
[599-79-1].» Sulfasalazine contains not less than 97.0 percent and not more than 101.5 percent of C18H14N4O5S, calculated on the dried basis.
Packaging and storage—
Preserve in tight, light-resistant containers.
Identification—
Loss on drying 
731
—
Dry it at 105
for 2 hours: it loses not more than 1.0% of its weight.
731—
Dry it at 105 for 2 hours: it loses not more than 1.0% of its weight.
Residue on ignition 281:
not more than 0.5%.
281:
not more than 0.5%.
Chloride 221—
Digest 2.0 g of Sulfasalazine with 100 mL of water at 70 for 5 minutes. Cool immediately to room temperature, and filter. Transfer a 25-mL portion of the filtrate to a 50-mL beaker (retain the remainder of this filtrate for the Sulfate test), add 1 mL of nitric acid, mix, and allow to stand for 5 minutes. Filter through a fine texture, retentive filter paper (Whatman No. 42, or equivalent): the filtrate shows no more chloride than corresponds to 0.10 mL of 0.020 N hydrochloric acid (0.014%).
221—
Digest 2.0 g of Sulfasalazine with 100 mL of water at 70 for 5 minutes. Cool immediately to room temperature, and filter. Transfer a 25-mL portion of the filtrate to a 50-mL beaker (retain the remainder of this filtrate for the Sulfate test), add 1 mL of nitric acid, mix, and allow to stand for 5 minutes. Filter through a fine texture, retentive filter paper (Whatman No. 42, or equivalent): the filtrate shows no more chloride than corresponds to 0.10 mL of 0.020 N hydrochloric acid (0.014%).
Sulfate 221—
Transfer a 25-mL portion of the filtrate from the Chloride test to a 50-mL beaker. Add 1 mL of 3 N hydrochloric acid, mix, and allow to stand for 5 minutes. Filter through a fine texture, retentive filter paper (Whatman No. 42, or equivalent): the filtrate shows no more sulfate than corresponds to 0.20 mL of 0.020 N sulfuric acid (0.04%).
221—
Transfer a 25-mL portion of the filtrate from the Chloride test to a 50-mL beaker. Add 1 mL of 3 N hydrochloric acid, mix, and allow to stand for 5 minutes. Filter through a fine texture, retentive filter paper (Whatman No. 42, or equivalent): the filtrate shows no more sulfate than corresponds to 0.20 mL of 0.020 N sulfuric acid (0.04%).
Heavy metals, Method II 231:
0.002%.
231:
0.002%.
Chromatographic purity—
Prepare a solution of Sulfasalazine in a mixture of alcohol and 2 M ammonium hydroxide (4:1) having a concentration of 10 mg per mL. Similarly prepare a Standard solution of USP Sulfasalazine RS in the same medium having a concentration of 10 mg 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 20 µg per mL, corresponding to 2.0%, 1.5%, 1.0%, and 0.2%, respectively (Standard dilutions A, B, C, and D). Separately apply 10-µL each of the test solution, the Standard solution, and the Standard dilutions to a suitable thin-layer chromatographic plate (see Chromatography 621) 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 UV light: the RF value 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%.
621) 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 UV light: the RF value 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%.
Assay—
Transfer about 150 mg of Sulfasalazine, accurately weighed, to a 100-mL volumetric flask. Dissolve in 0.1 N sodium hydroxide, dilute with 0.1 N sodium hydroxide to volume, and mix. Transfer 5.0 mL of this solution to a 1000-mL volumetric flask containing about 750 mL of water, mix, add 20.0 mL of 0.1 N acetic acid, dilute with water to volume, and mix. Concomitantly determine the absorbances of this solution and of a Standard solution of USP Sulfasalazine RS in the same medium having a known concentration of about 7.5 µg per mL, at the wavelength of maximum absorbance at about 359 nm, using water as the blank. Calculate the quantity, in mg, of C18H14N4O5S in the Sulfasalazine taken by the formula:
20C(AU / AS)
in which C is the concentration, in µg per mL, of USP Sulfasalazine RS in the Standard solution, and AU and AS are the absorbances obtained from the assay solution and the Standard solution, respectively.
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
Chromatographic Column—
| Topic/Question | Contact | Expert Committee |
| Monograph | Behnam Davani, Ph.D., M.B.A.
Senior Scientist 1-301-816-8394 |
(MDAA05) Monograph Development-Antivirals and Antimicrobials |
| Reference Standards | Lili Wang, Technical Services Scientist 1-301-816-8129 RSTech@usp.org |
USP32–NF27 Page 3632
Pharmacopeial Forum: Volume No. 34(3) Page 653
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.