Enhanced electrochemical detection of multi-heavy metal ions using a biopolymer-coated planar carbon electrode

In this study, a chitosan biopolymer-coated planar carbon electrode was developed for in situ determination of heavy metals (Zn 2+ and Pb 2+ ) using square wave anodic stripping voltammetry (SWASV). 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 0.1M acetate buffer at pH 4.6. Two distinguished peaks were observed at −0.86 and −0.37V, which are associated with the stripping of Zn 2+ and Pb 2+ , respectively. Limit of detection (LOD) was 0.6 and 1 ppb for Zn 2+ and Pb 2+ , respectively, and the relative standard deviations (RSD) for repetitive measurements of Zn 2+ and Pb 2+ were in the range of 4.8–5.4 % (n=30 with two identical electrodes). Overall, the developed biopolymer-coated carbon electrode exhibited excellent representativeness and reproductivity for in situ multi heavy metal ions detection in spiked samples, holding a great promise for on-site testing of heavy metals in drinking water.