Electrochemical detection of arsenic in drinking water using low-cost electrode

Abstract

The present paper explores the applicability of commercially available pencil graphite as a working electrode for electrochemical detection of arsenic As(III) contamination present in water in a systematic manner. The obtained result is also compared with a standard platinum-disc working electrode. The anodic stripping voltametry (ASV) technique is used to detect As(III) electrochemically in acidic medium. The optimum parameters for ASV are estimated for both pencil graphite and platinum-disc working electrodes. The calibration curve for As(III) detection in micro and nano molar range, i.e. oxidation current as a function of As(III) concentration is estimated from the different ASV traces recorded with optimized ASV parameters for various As(III) concentrations. In case of pencil graphite electrode, a good linearity in calibration curve throughout the nM concentration range is observed in the As(III) concentration range 2.5 nM −13.0 nM and limit of detection (LoD) of As(III) in water is found be lower than 2.5 nM. The platinum-disc electrode shows a LoD down to 1 µM and subtle linearity is observed in a narrow range of concentration range 1–6 µM. The observed LoD of As(III) for commercially available pencil graphite i.e. 2.0 nM is found to be far lower the WHO recommended permissible limit of arsenic (∼0.13 µM) in drinking water. Therefore, the commercially available pencil graphite can be used as working electrode for electrochemical to perform the As(III) contamination assessment in single-used format in a reliable manner.