ALL-SOLID-STATE SODIUM-SELECTIVE ELECTRODE BASED ON A CALIXARENE IONOPHORE IN A POLY(VINYL CHLORIDE) MEMBRANE WITH A POLYPYRROLE SOLID CONTACT

Sodium-selective coated wire electrodes (CWE) and solid contact (SC) electrodes have been constructed and investigated. The CWE is based on the application of a poly(vinyl chloride) (PVC) membrane incorporating the sodium-selective ionophore tetraethyl ester of p-tert-butylcalix[4]arene onto the surface of a platinum disk. The SC electrode is based on the use of a conducting polymer, polypyrrole (PPy), doped with NaBF4 as the mediating layer between platinum and the same PVC membrane as above. Nernstian responses have been obtained for both electrodes and comparable selectivities to that of a conventional ion-selective electrode (ISE) based on the same ionophore. Impedance measurements of the PPy and PVC layers and potentiometric studies of the membranes have been used to investigate the mechanism of the charge transfer of the systems.