SEPARATION OF SULFISOXAZOLE, PHENAZOPYRIDINE, AND THEIR RELATED IMPURITIES BY MICELLAR ELECTROKINETIC CHROMATOGRAPHY

A micellar electrokinetic chromatographic method for the analysis of s ulfisoxazole, phenazopyridine and their related known impurities in a tablet dosage form has been developed and validated. Current methods e mployed for this dosage form involve the use of two separate ultraviol et spectrophotometric or titrimetric assay procedures for the determin ation of the actives. Traditional reversed-phase high performance liqu id chromatographic separations of sulfisoxazole and its major degradat ion products, sulfanilamide and sulfanilic acid, result in the elution of the latter two components at or near the void volume, causing prob lems with their identification and quantitation. The micellar electrok inetic chromatographic method described here employs sodium dodecyl su lfate as the surfactant and effectively separates sulfisoxazole, phena zopyridine and all but two of their related impurities within thirty m inutes. The method was found to be valid with respect to specificity, linearity and limits of detection. System precision, however, was rela tively poor. Application of the method to the quantitation of these co mponents in a tablet dosage form is presented.