Green chelating IDS–Fe3O4 composite sensor for trace simultaneous detection of Cd2+, Pb2+, and Hg2+ in water samples

Abstract

Heavy metal ions such as Cd2+, Pb2+, and Hg2+ pose significant environmental and public health concerns du to their toxicity and persistence. In this study, a sensitive electrochemical sensor based on a tetrasodium iminodisuccinate/SiO2-coated Fe3O4-modified carbon paste electrode (IDS–Fe3O4@SiO2/CPE) was developed for the simultaneous determination of these metal ions using differential pulse voltammetry. The synergistic integration of SiO2-coated Fe3O4 nanoparticles with IDS enhanced the electrochemical performance of the sensor by improving electron-transfer kinetics, increasing the electroactive surface area, and providing effective surfaceactive sites for metal-ions accumulation. Under optimized conditions (pH 1.0, 0.1 M HNO3/NaNO3, and 10 mg modifier), the proposed sensor exhibited dual linear ranges of 0.03–0.9 and 3.0–100 μM for Cd2+, 0.01–1.0 and 5.0–100 μM for Pb2+, and 0.004–0.9 and 3.0–90 μM for Hg2+, with limits of detection of 0.0097, 0.0034, and 0.0012 μM, respectively. The sensor demonstrated satisfactory analytical performance, good repeatability, and operational stability over 21 days (RSD = 3.81%). Although noticeable interference was observed for Cu2+, CH3COO−, and NH4+, reliable quantitative determination of Cd2+, Pb2+, and Hg2+ in real environmental water samples was successfully achieved using the standard addition method, providing recoveries between 94% and 110%. Owing to its simplicity, low cost, environmental compatibility, and competitive analytical performance, the proposed sensor represents a promising platform for trace-level monitoring of heavy metal contaminants in aquatic environment