Characterization of novel electrodes for use in the detection of biotoxic traces metal ions in the environment

Abstract

Heavy metals are difficult to remove from the environment and, unlike many other pollutants, cannot be chemically or biologically degraded and are ultimately indestructible. Today, many heavy metals constitute a global environmental hazard, analyzes of air, water and soil samples indicate that the contamination and accumulation of toxic metals are continuously increasing. Therefore the determination of heavy metals becomes important. Electrochemical methods use the possibility to concentrate the analyte on the electrode surface in a previous stage for subsequent anodic oxidation of the accumulated material. Most analyzes of heavy metals occurs in natural samples, usually containing some substances that react or adsorb on the electrode surface. These substances often adsorb on the electrode surface disturbing or blocking the deposition of the analyte. Therefore, the aim of the present work is to develop modified electrodes with films of bismuth and Nafion as a protective film for the determination of Cu2+, Pb2+ and Cd2+. Particular interest will be addressed to the fabrication of microelectrode of micrometric dimensions and with short response times, so that measurements are performed on-site sampling and the attempt to lower the detection limits for quantification of metal ions. The properties of the interfacial region of the modified electrodes will be investigated by electrochemical impedance spectroscopy with particular emphasis on the detection of metal ions by anodic stripping voltammetry. (AU)