ELECTROCHEMICAL SENSORS FOR CU(II) AND NI (II) POTENTIOMETRIC DETERMINATIONS

Four electrodes with liquid membrane, Cu2+ - selective and Ni2+ - sele ctive respectively, not described previously in the Literature, were p repared and characterized. From these electrodes 1 and 2 are based on simple complexes of Cu(ll) and Ni(ll) with 6, 7-dinitro-quinoxaline-2, 3-dithiol as ligand belonging to the dithiols class, whereas electrode s 3 and 4 are based on tbe corresponding mired complexes in which the ammonia molecule enters as the second ligand along with 6,7-dinitro-qu inoxaline-2,3-dithiol (6,7-dinitro-Q.D.T.), respectively, as the first ligand. There were determined the primary and secondary characteristi cs of these electrodes as well as the selectivity constants, for their practical use to a potentiometrical dose of Copper and Nickel. The ad vantages of using mired complexes as electroactive species in realizin g ion-selective electrodes were evidentiated.