Determination of sulphonated azo dyestuffs and their bacterial metabolites by high-performance liquid chromatography

Abstract Mixtures of single- and multiple-substituted benzene and naphthalene sulphonic acids and azo dyestuffs were separated by high-performance liquid chromatography using gradient elution on reversed-phase columns. A UV detector was used. The mobile phase was 100 m M potassium phosphate buffer (pH 6.7) and the polarity was modified by the addition of methanol. Multiple acidic substituents required the buffer to be pH 2.