Simultaneous determination of trace Cd²⁺ and Pb²⁺ using GR/l-cysteine/Bi modified screen-printed electrodes

A GR/l-cys/Bi/SPE (reduced graphene oxide/l-cysteine/Bi/screen-printed electrode) was prepared to simultaneously determine Cd²⁺ and Pb²⁺ ions by using SWASV (square wave anodic stripping voltammetry). The experimental conditions of the Cd²⁺ and Pb²⁺ determination including the deposition potential, the deposition time, pH and the Bi³⁺ concentration were optimized. Well-defined peaks of Cd²⁺ and Pb²⁺ ions could be achieved. Under the optimized conditions, the calibration curves were obtained in linear ranges from 10 μg L^-1 to 50 μg L^-1 for Cd²⁺ and from 10 μg L^-1 to 50 μg L^-1 for Pb²⁺, with detection limits of 0.98 and 0.56 μg L^-1, respectively. Their fitting equations are I (μA) = 0.13C (μg L^-1) + 0.60 (R² = 0.9976) for Cd²⁺ ions and I (μA) = 0.10C (μg L^-1) + 0.51 (R² = 0.9896) for Pb²⁺ ions, respectively. The GR/l-cys/Bi/SPE exhibits many merits such as high selectivity, low detection limits, low fabrication costs and wide linear ranges. The GR/l-cys/Bi/SPE has great potential for the determination of Cd²⁺ and Pb²⁺ in real water samples.