Quantitative analysis of cadmium(II) and copper(II) by chemical stripping chronopotentiometry using dissolved oxygen as an oxidant

Chemical stripping chronopotentiometry was applied to determine cadmium(II) and copper(II) by using oxygen as an oxidant. The calibration curve for cadmium(II) was linear within a range of (10-6--10-4) mol dm-3, while the calibration curve for copper(II) was distorted, since copper(II) ion in the sample solution also worked as an oxidant. The calibration curve for cadmium(II) in the presence of constant concentration of copper(II) ion was linear within the range of (10-5--2 x 10-4) mol dm-3. In order to determine copper(II) in the presence of cadmium(II), it was necessary to electrodeposit only copper by reducing at -0.5 V vs. SCE. The instrumentation used in this work was composed of only a simple voltage supply circuit, a stirrer, a y-t recorder and a pH-meter used as a high-impedance potentiometer. (author)