Copper(I) electrode function of two types of copper(II) ion-selective electrodes.
The response of two types of solid-state copper ion-selective electrodes with homogeneous membranes of CuAgSe and Cu(2-x)Se has been investigated in copper(I) solutions, prepared electrochemically by insitu generation from a copper anode in chloride medium. The selectivity coefficient K(pot)(Cu+, Cu(2+)) both types of electrodes has been determined. It is 10(-5.7) for the copper selenide sensor, and 10(-6.2) for the copper silver selenide one. These values are very close to that calculated for an exchange reaction proceeding on the electrode surface. The similarity in K(pot)(Cu+ ,Cu(2+)) values for different chalcogenidebased sensors suggests a common potential-generating mechanism. High chloride concentration does not interfere with the electrode response towards Cu(I), but distorts the electrode response to Cu(II).
Calibration of a solid-state copper ion-selective electrode in cupric ion buffers containing chloride.
It is shown that near-Nernstian calibration slopes can be obtained with a Cu(1.8)Se electrode in a range of cupric ion buffers in spite of a high chloride content. Best results are obtained with the ligands ethylenediamine, glycine and histidine. The onset of cupric ion toxicity towards marine organisms falls within the pCu calibration range obtained with glycine, and the Cu(1.8)Se electrode could, therefore, be useful for monitoring cupric ion activity in bioassays in sea-water media.
The preparation and analytical evaluation of a new heterogeneous membrane electrode for cadmium(ii)
Abstract The preparation of a new cadmium-selective heterogeneous membrane electrode obtained by hot-pressing a mixture of cadmium and silver sulfides with polythene in a moulding press is described. Nernstian response to cadmium ion was achieved only when the mixture of salts was purified by heat treatment at 600° in an atmosphere of hydrogen sulfide for several hours. This behaviour is discussed in terms of the purity of the salts. Interferences and analytical applications in aqueous and nonaqueous solvents are described.