A direct analysis of nanomolar metal ions in environmental water samples with Nafion-coated microelectrodes

Abstract

Square Wave Anodic Stripping Voltammetry (SWASV) was combined with microfabricated microelectrodes to analyze metal ions in aqueous solution and showed excellent performance such as short analysis time about I min per experiment, simultaneous detection of several ions and very low detection limit as low as several nanomoles per liter (i.e. sub-ppb in mass) without any of supporting electrolyte and stirring during analysis. Nafion, a famous ion-exchanging polymer, was introduced to protect the electrode surface from obstructing materials. The Nafion-co ted microelectrode was free from disturbing impurities and was capable of analyzing natural water samples directly. Results from the direct water analysis showed similar performance to those from pre-treated samples in both sensitivity and analysis time. To secure the reproducibility of Nalion-coated electrode, a simple electrochemical cleaning method with potential sweep was used and the electrode remained reliable to continued experiments. Nafion-coated microelectrodes were further examined via the comparison with ICP-MS data. (C) 2004 Elsevier Ltd. All rights reserved.