Elimination of the acetate interference in potassium-selective valinomycin-PVC-membranes for process-controlling during haemodialysis

Abstract

Valinomycin-PVC-membranes of potassium-selective electrodes, which were used up to now, show for process controlling during haemodialysis in the presence of dialytic solutions including acetate, an anion interference which has to be corrected. On the basis of experimental examinations on the influence of plasticizers, lipophilic anions and different concentrations of ionophoric transport-antibiotics on the nature of membranes, an optimized application could be realized. But surprisingly, the incorporation of lipophilic anions like tetrakis(4-chlorophenyl)borate induces a significant acetate anion interference. Otherwise, when avoiding this lipophilic anion in PVC-membranes with a saturation of valinomycin on oxygen-independent solid-state contact sensors, an elimination of acetate anion interference is achieved if bis(2-ethylhexyl)sebacate is used as plasticizer.