Voltammetric determination of cadmium using magnetic graphite-epoxy composite electrode modified with magnetic nanoparticles

In this study, a new analytical method for determining cadmium (Cd2+) was developed, combining dispersive magnetic solid-phase extraction (DMSPE) and voltammetric analysis using a magnetic graphite-epoxy composite electrode (m-GEC). The method utilizes a magnetic adsorbent, m-poly(ATU)-PAN, which consists of poly(allylthiourea) functionalized with the 1-(2-pyridylaz)-2-naphthol (PAN) ligand, providing high adsorption capacity for Cd2+ extraction. The m-poly(ATU)-PAN adsorbent was characterized by FTIR (Fourier Transform Infrared Spectroscopy), XRD (X-ray Diffraction), textural parameters, and TEM (Transmission Electron Microscopy), revealing reduced porosity and specific surface area after PAN functionalization, indicating successful modification of the polymer. The material's complex morphology favors the adsorption of Cd2+. The extraction and determination process involves two main steps: (1) Cd2+ extraction via DMSPE using m-poly(ATU)-PAN, and (2) Cd2+ detection using square wave anodic stripping voltammetry (SWASV) on m-GEC. Experimental conditions, including sorbent amount, pH, extraction time, and voltammetric parameters, were optimized. Compared to other methods for Cd2+ extraction and preconcentration, the proposed approach showed significant advantages, including a high anodic peak current for a sample at a Cd2+ concentration of 50.0 μg L−1. The method demonstrated good repeatability, stability, and low detection and quantification limits. Finally, the proposed sensor proved promising for the electrochemical determination of Cd2+ in water and cocoa bean samples, offering potential applications in environmental monitoring and food safety.