Detection of bioactive surfactants in aqueous solutions on the basis of H2O2-voltammetry

The voltammetric determination of surfactants at the hanging mercury drop electrode in aqueous solutions is described, based on the shift of the peak potential deltaEp or the increase of the peak height deltaip of the electroreduction of hydrogen peroxide or of the second oxygen reduction step, with increasing concentration of surfactants. Although the selectivity of this method is rather limited, it could be utilized, e.g., for monitoring the absence (or presence) or for the determination of the contents of specified surfactants by comparing the obtained deltaip (deltaEp) signal with the reference state of the system or with that of a selected reference surface active substance. As model surfactants n-octanol, tetrabutylammonium chloride and sodium dodecylbenzenesulfonate were used, the regular adsorption behavior of which is well known. The method was successfully applied to control the presence of a commercial detergent in water for rinsing bottles for infusion solutions.