Enhanced Electrochemical Detection of Multiheavy Metal Ions Using a Biopolymer-Coated Planar Carbon Electrode

In this paper, a chitosan biopolymer-coated planar carbon electrode was developed for in situ determination of heavy metals (Zn2+ and Pb2+) using square-wave anodic stripping voltammetry. The experimental conditions were optimized with respect to deposition time, amplitude, and frequency. With 300-s deposition time, the heavy metal stripping was conducted at 0.05-V pulse amplitude, 20-Hz pulse frequency, and 0.004-V square-wave step voltage in 0.1-M acetate buffer at pH 4.6. Two distinguished peaks were observed at -0.86 and -0.37 V, which are associated with the stripping of Zn2+ and Pb2+, respectively. The limit of detection was 0.6 and 1 ppb for Zn2+ and Pb2+, respectively, and the relative standard deviations for repetitive measurements of Zn2+ and Pb2+ were in the range of 4.8%-5.4% (n = 30 with two identical electrodes). The chitosan biopolymer-coated carbon electrode was successfully applied for detecting Pb2+ in tap water, mining wastewater, and soil leachate, and showed a reliable performance for measuring heavy metals with acceptable reproducibility. Overall, the developed biopolymer-coated carbon electrode exhibited excellent representativeness and reproductivity for in situ multiheavy metal ions detection in spiked samples, holding a great promise for on-site testing of heavy metals in drinking water.