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

A micellar electrokinetic chromatographic method for the analysis of sulfisoxazole, phenazopyridine and their related known impurities in a tablet dosage form has been developed and validated. Current methods employed for this dosage form involve the use of two separate ultraviolet spectrophotometric or titrimetric assay procedures for the determination of the actives. Traditional reversed-phase high performance liquid chromatographic separations of sulfisoxazole and its major degradation products, sulfanilamide and sulfanilic acid, result in the elution of the latter two components at or near the void volume, causing problems with their identification and quantitation. The micellar electrokinetic chromatographic method described here employs sodium dodecyl sulfate as the surfactant and effectively separates sulfisoxazole, phenazopyridine and all but two of their related impurities within thirty minutes. The method was found to be valid with respect to specificity, linearity and limits of detection. System precision, however, was relatively poor. Application of the method to the quantitation of these components in a tablet dosage form is presented.