Electroanalytical study of succinylsulfathiazole and phtalylsulfathiazole at a glassy carbon electrode

An electroanalytical study of succinylsulfathiazole and phtalylsulfathiazole oxidation processes at a glassy carbon electrode using different voltammetric techniques was carried out. Results obtained at a rotating disk electrode allow the determination of the pK a values of the reduced and oxidized forms. Limiting currents are diffusion controlled in concentration ranges of 1.0 × 10 −5 to 5.0 × 10 −5 and 2.0 × 10 −5 to 6.0 × 10 −5 mol L −1 for Succinylsulfathiazole and phtalylsulfathiazole, respectively. Adsorption phenomena occur at higher concentrations, becoming stronger as the acidity of the medium increases. From differential pulse voltammetry at a stationary electrode, the limits of determination were 3.7 × 10 −6 and 4.7 × 10 −6 mol L −1 for succinylsulfathiazole and phtalylsulfathiazole, respectively. Interferences between the two sulfa drugs were studied. The application of differential pulse voltammetry at a stationary electrode gave good results for the determination of phtalylsulfathiazole in a commercial pharmaceutical preparation.