Metallo-graphene nanocomposite electrocatalytic platform for the determination of toxic metal ions

Abstract

A Nafion-Graphene (Nafion-G) nanocomposite solution in combination with an in situ plated mercury film electrode was used as a highly sensitive electrochemical platform for the determination of Zn2+, Cd2+, Pb2+ and Cu2+ in 0.1 M acetate buffer (pH 4.6) by square-wave anodic stripping voltammetry (SWASV). Various operational parameters such as deposition potential, deposition time and electrode rotation speed were optimized. The Nafion-G nanocomposite sensing platform exhibited improved sensitivity for metal ion detection, in addition to well defined, reproducible and sharp stripping signals. The linear calibration curves ranged from 1 µg L−1 to 7 µg L−1 for individual analysis. The detection limits (3σ blank/slope) obtained were 0.07 µg L−1 for Pb2+, Zn2+ and Cu2+ and 0.08 µg L−1 for Cd2+ at a deposition time of 120 s. For practical applications recovery studies was done by spiking test samples with known concentrations and comparing the results with inductively coupled plasma mass spectrometry (ICP-MS) analyses. This was followed by real sample analysis.