High pressure liquid chromatographic determination of sulfisoxazole in pharmaceuticals and separation patterns of other sulfonamides.

A high pressure liquid chromatographic method has been developed for the identification and determination of sulfisoxazole in tablet, liquid, and ointment dosage forms. The method specifies a mu Bondapak C18 column, an acetonitrile-acetic acid-water (22.5 + 1 + 76.5) mobile phase, and ultraviolet detection at 254 nm. For quantitative purposes, sulfabenzamide is used as an internal standard. Commercial preparations were analyzed by the proposed method and results were compared with those obtained by the U.S. Pharmacopoeia XIX and National Formulary XIV methods; good agreement was obtained. The elution behaviors of 19 additional sulfonamides were also established to verify the specificity of the proposed method for sulfisoxazole. These elutions patterns show potential for separation and identification of all 20 sulfonamides.