A high-performance biopolymer sensor based on dialdehyde starch-vanadium pentoxide nanocomposite for selective and sensitive voltammetric detection of Pb(II), Cd(II), and Zn(II) ions

Heavy metal pollution poses severe environmental and health risks, necessitating sensitive and eco-friendly detection methods. The present work introduces a novel electrochemical sensor based on a dialdehyde starch-vanadium pentoxide (DAS-V₂O₅) nanocomposite-modified carbon paste electrode (CPE) for simultaneous voltammetric detection of Pb²⁺, Cd²⁺, and Zn²⁺. Via a straightforward chemical protocol, dialdehyde starch serves as a biodegradable scaffold that facilitates the homogeneous dispersion of V₂O₅ nanoparticles, leading enhance both the electrode’s active surface area and metal ion adsorption capacity. The modifier was characterized using FRIT, XRD, SEM, and EDX. The electrochemical performance of the DAS-V₂O₅ NPs/CPE was evaluated using differential pulse voltammetry (DPV) for the simultaneous detection of Pb²⁺, Cd²⁺, and Zn²⁺ in aqueous solutions. Under optimized differential pulse voltammetry (DPV) conditions, the sensor displayed a strictly linear relationship between peak current and concentration for Zn²⁺, Cd²⁺, and Pb²⁺. The corresponding linear dynamic ranges and limits of detection (LODs) were as follows: Zn²⁺, 4.0 nM–20.0 µM (LOD = 0.092 nM); Cd²⁺, 8.0 nM–25.0 µM (LOD = 0.60 nM); Pb²⁺, 3.0 nM–23.0 µM (LOD = 0.046 nM), which showed the nanocomposite modification significantly enhanced the electrode’s sensitivity, with detection limits well below the World Health Organization (WHO) permissible limits. The sensor exhibited excellent selectivity, reproducibility (RSD < 4%), and stability (> 95% signal retention after 4 weeks). The practical applicability of the DAS- V₂O₅NPs/CPE was evidenced through its analysis of real water samples achieving recoveries of 93.45–100.65%, highlighting its reliability for environmental monitoring. This green chemistry-aligned sensor offers a promising tool for on-site heavy metal detection in environmental and industrial samples.