Multiple square wave voltammetry of nanomolar and subnanomolar concentrations of europium(III) at polymer-coated electrodes

The ion-exchange voltammetric determination of europium(III) at polymer-coated electrodes is examined. The comparison between the ion-exchange cyclic voltammetric behaviour at glassy carbon electrodes, modified with the poly(estersulfonate) Kodak AQ55 and Nafion, indicates a better suitability of the latter. The use of multiple square wave voltammetry (MSWV) results in a dramatic improvement of the signal-to-noise ratios of the voltammograms recorded at the modified electrodes. Eu(III) determinations by MSWV at Nafion-coated electrodes are characterised by detection limits 2¯3 orders of magnitude lower than those obtained with differential pulse voltammetry and the rare earth cation can be analysed at nano- and subnanomolar levels, depending on the experimental conditions adopted.