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% (<inline-formula> <tex-math notation="LaTeX">$n = 30$ </tex-math></inline-formula> 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 <italic>in situ</italic> multiheavy metal ions detection in spiked samples, holding a great promise for on-site testing of heavy metals in drinking water.