Advances in multiple square wave techniques for ion-exchange voltammetry at ultratrace levels: the europium(III) case

This paper reports on the use of multiple square wave voltammetry, MSWV, fo r the determination of europium(III) preconcentrated by ion-exchange at gla ssy carbon electrodes coated with Nafion(R). For this aim, a double-differe ntial (DD) mode of MSWV is implemented; with this mode, background signals are always straight lines while the analyte signal is given as a twin oppos ite peak system which corresponds approximately to the instrumental double differential of the classical voltammetric wave. The influence of scan para meters and experimental conditions on MSW-DD responses for europium(III) de terminations at the modified electrode is examined. Detection limits and se nsitivities obtained using MSW-DD are significantly superior to those achie vable by classical pulsed techniques. The method is applied to the determin ation of ultratrace europium(III) concentrations in the 10(-11)-10(-10) hi range in the cooling water of a nuclear plant; results obtained by the MSW- DD ion-exchange voltammetric approach compare well with those obtained by I CP-MS. (C) 2001 Elsevier Science B.V. All rights reserved.