Direct ultrasensitive redox sensing of mercury using a nanogold platform

Abstract

Rapid industrialization and innovative material processing routes have resulted in the contamination of natural resources. Qualitative and quantitative estimation of mercury in food, beverages, water sources, and other environmental media has become of prime importance for human well-being. The present healthcare sector desires cheap, easy to use, and portable field-based monitoring kits for the detection of hazardous pollutants like mercury. In view of these facts, there is a strong need for robust, cost effective, reproducible, ultrasensitive, selective, and portable technology for the detection of mercury in samples. Here, we report the facile direct redox sensing of mercury ions at the ppb level. In this work, a combined application of linear sweep voltammetry (LSV) and chronoamperometry techniques was made for the direct electrochemical sensing of mercury ions on a nanogold platform. This is the first report in which the direct electrochemical sensing of mercury is demonstrated based on LSV & chronoamperometry techniques without the use of any biomolecule/co-coordinating ligand. ISV works in one direction/sweep, thereby diminishing the possible occurrence of interfering agents in a reverse sweep. This new approach is more reliable, robust, ultrasensitive, and user friendly relative to previous methods. The fabricated Au/Nafion/GC electrode showed ultra-high sensitivity of 11.75 A cm(-2) ppb(-1) [detection limit of 3.78 ppb (19 nM) with a linearity ranging up to 50 ppm] at a response time of <2 s, demonstrating wide applicability and efficacy of this technique for sensing mercury. (C) 2016 Published by Elsevier B.V.