Electrochemical Sensors for on-Site Detection of Toxic Metal Ions in Environmental Water Systems

Abstract

Easy to use devices for the rapid detection of toxic metal ions in drinking water is essential for improving monitoring, identification and management of water resources. In 2014, over 100,000 residents of Flint, Michigan, were exposed to high levels of lead in their drinking water, leading to serious environmental and health issues. The problem faced by Flint is a perfect example of the need for a portable device for on-site detection system that can sense the presence of high concentrations of toxic metal ions in the environment in natural pH with no sample pretreatment. In this work, an easy to use method for metal ion detection in natural water samples was developed. Preconcentration of ions at the electrode surface was achieved by optimizing a nanostructured layer consisting of gold nanoparticles and a conductive polymer, which improved detection sensitivity and selectivity withing limits that cover the EPA levels for metal ion exposure. The method was demonstrated for the detection of As, Pb and Hg in natural waters, using anodic stripping voltammetry (ASV). Several parameters were optimized in order to achieve the highest detection sensitivity, including pH, ionic strength and deposition time. Local water samples were tested for heavy metal ion content and validated using lab-based methods, including atomic absorption spectroscopy (AAS) and ICP-MS. This methodology was applied onto the surface of low-cost screen-printed electrodes which are easy to use and portable.