Anodic stripping voltammetric determination of cadmium using a “mercury free” indium film electrode

Abstract

In this work, the determination of cadmium has been attempted using an indium film electrode in the presence of bromide ions as an additive, for the first time. The electrode was prepared in situ on a glassy carbon substrate and employed in combination with square wave anodic stripping voltammetry. The purpose of having bromide ions is to enhance the analytical value of cadmium detection. In the absence of bromide ions, cadmium stripping peaks coalesce with indium and it is difficult to resolve for analytical purposes. The addition of bromide ions strongly influences the peak separation, thanks to the complex-forming characteristics of cadmium with bromide ions. Several key operational parameters influencing the electroanalytical response of indium modified electrodes were examined and optimized, such as deposition potential, pH, bromide ion and indium concentration. The indium modified electrode exhibited well-defined, separated stripping signals and revealed good linear behavior in the examined concentration range from 1 to 25 ng ml⁻¹. The present method shows a low detection limit value of 0.36 ng ml⁻¹. These results suggest that the proposed electrode contributes to the wider applicability of electrochemical stripping techniques in connection with “mercury-free” electrodes.