Sequential multi-element analysis using silver and copper ion-selective electrodes

Abstract

A simple method is described for the rapid and accurate sequential determination of as little as 50 µg ml^–1 of Ag⁺, Cu²⁺, Ni²⁺, Cd²⁺, Pb²⁺, Zn²⁺, Fe³⁺, Th⁴⁺ and V⁴⁺ ions in binary, tertiary and quaternary mixtures. The method involves direct titration with sodium diethyldithiocarbamate at pH 4–6 in 50%V/V ethanol using silver and copper ion-selective electrodes. Potentiometric curves with sharp consecutive inflection breaks at the equivalence points and a mean recovery of 99.6%(mean standard deviation 0.3%) are obtained. The method has been used satisfactorily for the determination of the major alloying elements in brass, motor-brass, silver-brazing and nickel-silver alloys by both direct and spiking titration techniques. The results agreed well with the certified values.