Effect of structure and properties of membrane active substance on analytical performance of ion-selective electrodes

The potential creating properties of a group of acidic chelating compounds are presented. The studies have been carried out by the constructing of new ion-selective electrodes based on PVC membranes doped with the studied compounds, and determining the basic analytical parameters of the electrodes. The usefulness of eight out of nine investigated compounds in the preparation of the membrane phase electrodes selective for cobalt, zinc and cadmium has been shown. It has been also found that the acidic properties of ionophore have an essential influence on the analytical parameters of the constructed electrodes. The response mechanism of the obtained electrodes has been investigated by simultaneous spectrophotometric-potentiometric measurement of membranes used in electrodes. It has been found that during the conditioning of electrode, a complex of active substance with primary ion is formed in the membrane phase, then the membrane composition is established and remains unchanged in the next measurements