C9H8N3NaO2S2,11⁄2H2O 304.3 144-74-1(anhydrous)
C9H8N3NaO2S2,5H2O 367.4 6791-71-5
Action and use
Sulfonamide antibacterial.
DEFINITION
Sulfathiazole Sodium is the hydrated sodium salt of N -thiazol-2-yl sulfanilamide, either the sesquihydrate or the pentahydrate. It contains not less than 99.0% and not more than 101.0% of C9H8N3NaO2S2, calculated with reference to the dried substance.
CHARACTERISTICS
A white or yellowish white, crystalline powder or granules.
Freely soluble in water; soluble in ethanol (96%).
IDENTIFICATION
A. The infrared absorption spectrum of the dried substance, Appendix II A, is concordant with the reference spectrum of sulfathiazole sodium (RSV 42).
B. Dissolve 1 g in 25 mL of water and add 2 mL of 6M acetic acid. The melting point of the precipitate, after washing with water and drying for 4 hours at 105°, is about 201°, Appendix V A.
C. The precipitate obtained in test B yields the reaction characteristic of primary aromatic amines, Appendix VI, giving an orange-red precipitate.
TESTS
Alkalinity
pH of a solution containing the equivalent of 1.0% w/v of the anhydrous substance, 9.0 to 10.0, Appendix V L.
Heavy metals
Dissolve a quantity containing the equivalent of 2.5 g of the anhydrous substance in 10 mL of water, add 15 mL of 2M acetic acid, shake for 30 minutes and filter. 12 mL of the resulting solution complies with limit test A for heavy metals, Appendix VII. Use lead standard solution (2 ppm Pb) to prepare the standard (20 ppm).
Related substances
Carry out the method for thin-layer chromatography, Appendix III A, using silica gel H as the coating substance and a mixture of 18 volumes of 10M ammonia and 90 volumes of butan-1-ol as the mobile phase. Apply separately to the plate 10 μL of each of two solutions in a mixture of 1 volume of 13.5M ammonia and 9 volumes of ethanol (96%) containing (1) 1.0% w/v of the substance being examined and (2) 0.0050% w/v of sulfanilamide. After removal of the plate, heat it at 105° for 10 minutes and spray with a 0.1% w/v solution of 4-dimethylaminobenzaldehyde in ethanol (96%) containing 1% v/v of hydrochloric acid. Any secondary spot in the chromatogram obtained with solution (1) is not more intense than the spot in the chromatogram obtained with solution (2) (0.5%).
Loss on drying
When dried to constant weight at 105°, loses not less than 6.0% and not more than 10.0% of its weight (sesquihydrate) or not less than 22.0% and not more than 27.0% of its weight (pentahydrate).
ASSAY
Dissolve 0.5 g in a mixture of 75 mL of water and 10 mL of hydrochloric acid, add 3 g of potassium bromide, cool in ice and titrate slowly with 0.1M sodium nitrite VS, stirring constantly and determining the end point electrometrically. Each mL of 0.1 M sodium nitrite VS is equivalent to 27.73 mg of C9H8N3NaO2S2.
STORAGE
Sulfathiazole Sodium should be protected from light.
LABELLING
The label states whether the substance is the sesquihydrate or the pentahydrate.
