Potentiometric Responses of Ion-Selective Membranes Containing Mixtures of Two Different Ionophores

Research related to optical sensors (optodes) directed the attention towards plasticized polymeric membranes containing more than one ionophore at the same time. Studying the potentiometric behavior of such membrane systems helps to characterize the effect of cross-contamination in multi-electrode systems used for biomedical applications. In this article, a theoretical model is introduced, which describes the potentiometric behavior of membranes doped with two different ion carriers. The theory is compared to those results obtained with a model system containing both K+ and H+-ionophores in the membrane phase. The study has also been extended to ion-selective membranes containing two other ion-selective carriers in different ratios. These results give guidelines to optimize the physical arrangement of potentiometric multi-electrode systems.