RESPONSE PROPERTIES OF AN ION-SELECTIVE POLYMERIC MEMBRANE PHOSPHATE ELECTRODE PREPARED WITH COBALT PHTHALOCYANINE AND CHARACTERIZATION OF THE ELECTRODE PROCESS

The investigation of phosphate selective coated-wire electrodes based on cobalt phthalocyanine (CoPc-based CWE) is described. This electrode was not only applied as an indicator electrode in potentiometric titrations but also as a chemically modified electrode for cyclic voltammetry. The effect of pH on the response potential of the CoPc-based CWE was investigated in phosphate solutions of different pH buffer. The electrode responded to the dihydrogenphosphate anion solution and gave a response slope of 42-45 mV in pH = 4-7. The evaluation of behaviour following ion exchange or charge transfer on the electrode was made by using ultraviolet spectrophotometry, voltammetry and X-ray fluorescence analysis. It was found that CoPc-based CWEs have an ion exchange mechanism based on the adsorption of phosphate and the interaction of the phosphate anion adsorbed with CoPc contained in the PVC membrane of the CWE. The scheme of the CWE mechanism in cyclic voltammetry has been proposed. © 1990.