Novel electrochemical sensing of arsenic ions using a simple graphite pencil electrode modified with tin oxide nanoneedles

Abstract

Electrochemical sensors have attained enormous attention in last few years. Various contaminants like pesticides, explosives, pharmaceutical drugs, and biological fluids have been determined qualitatively as well as quantitatively with the assistance of cyclic voltammetry (CV), linear sweep voltammetry (LSV), amperometry, and impedance-based techniques. Nanoengineering based modified electrodes have contributed to the establishment of the on-site detection platform for various harmful analytes with the aid of electrochemical method. In this research, CV-based detection method has been developed and validated against arsenic (As3+) in real as well as laboratory samples. Lead pencil (cost around 0.015 USD) has been utilized as working electrode after modification with tin oxide (SnO2) nanoneedles. SnO2 nanoneedles (size: 60-80 nm), synthesized using chemical precipitation method, were characterized for their elemental, topological, morphological and structural features. The surface of lead pencil (containing graphite/carbon (C)) was then coated with these nanoneedles with the help of nafion (as binding agent). This fabricated sensor recorded a detection limit of 10 ppb (linear range: 50-500 ppb) with ultrasensitivity of 28.13 mu A cm(-2) ppb(-1). This method was then applied to the direct ion quantitation of arsenic in real environmental and industrial samples collected from diverse locations.