Cation‐Response Mechanism of Neutral Carrier Based Ion‐Selective Electrode Membranes

Results of voltammetric, potentiometric, chronoamperometric, ion transport, and extraction studies on neutral carrier based, plasticized poly(vinyl chloride) membranes are summarized. They unambiguously confirm that such bulk membranes dispose of immobile anionic sites. These fixed sites lead to a Donnan exclusion of other anions from the membrane and thus to a permselectivity for cations. The results are in perfect agreement with the predictions of earlier membrane models. A rigorous Poisson ‐ Boltzmann analysis of macroscopic liquid membranes clearly indicates that space‐charge at the membrane/solution interfaces does not influence the electrochemical properties and the ion‐selectivity behavior at steady state.