engleski

Adsorptive stripping voltammetric determination of biologically active azosalicylic acids

Electroanalytical methods, in particular voltammetric techniques, are well established in pharmaceutical and biomedical analysis. Adsorptive stripping voltammetry has been shown to be a sensitive analytical method for a wide range of organic compounds that adsorb in submonomolecular layer on electrode surface. It is based on a two step approach consisting of an initial pre-concentration step during which the analyte is allowed to accumulate at the electrode surface under carefully controlled condition and a subsequent measurement in which the accumulated analyte is then stripped-off and determined by a voltammetric method. Square-wave voltametry is one of the most advanced methods among the family of pulse voltammetric techniques applied in the stripping of the deposit. The sensitivity of the technique depends primarily on the kinetics of the redox reaction in the stripping phase. Biologically active azosalicylic acids, including drug Olsalazine presently used for the treatment of ulcerative colitis and Crohn’ s disease, exhibit surface-active properties at a mercury electrode. Square-wave voltammetry was used to investigate the adsorptive behaviour in aqueous medium in order to elucidate some specific properties of their electrode reaction. The kinetic parameters of the surface redox reaction, such as the standard rate constant and the electron transfer coefficient were determined. Electroanalytical procedures based on the reduction of azosalicylic acids at the hanging mercury drop electrode were developed. Adsorptive stripping square-wave voltammetry provides adequate detection limits for trace analysis of these azo compounds. The limit of determination obtained for olsalazine sodium is comparable to those found by using the chromatographic techniques, but the proposed method is more simple and time saving, utilizing relatively inexpensive instrumentation.

adsorptive stripping square-wave voltammetry; azosalicylic acid; olsalazine

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