Determination of Solubility of 4-(2-Hydroxyethyl)-1-piperazineethanesulfonic Acid and its Sodium Salt in Acetonitrile and Voltammetric Investigation of Sulphonamide Drugs in Different Solvents in Their Absence and Presence

Abstract Sulphonamide drugs (sulphamethazine, sulphamerazine, sulphadiazine, sulphathiazole) were studied in a wide potential window (between 2 and − V) acetonitrile, dimethyl sulphoxide 50–50 v/v% binary mixtures of acetonitrile water. The voltammograms the outlined compounds very similar both anodic cathodic part each non-aqueous solvents except for sulphathiazole. These sulphonamide also investigated presence 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) its sodium salt changed due to an acid–base reaction. HEPES could be only their saturation concentration as they slightly soluble this solvent. In separate experiment solubilities determined at 298 K with co-solvent calibration method using water co-solvent. Complementary fluorescence studies did not show any interaction between well salt.