Core–Shell Chitosan Cobalt Ferrite Nanoparticles for Ultrasensitive Simultaneous Voltammetric Determination of Pb(II) and Cd(II)

In water samples from industrial regions, the presence of highly toxic and nonbiodegradable heavy metal ions (HMI) poses a significant threat to environmental quality. While analytical methods based on mercury electrodes are widely recognized for their high performance in the sensitive and selective quantification of various metal contaminants, the development of environmentally friendly strategies for the voltammetric determination of HMI remains a formidable challenge. In this study, we propose a material utilizing small-size chitosan (CTS) cobalt ferrite core–shell nanoparticles (CoFe2O4@CTS) as an electrode modifier for the simultaneous voltammetric determination of Pb(II) and Cd(II). The magnetic nanoparticles were synthesized using the solvothermal method and characterized using various techniques to explore their crystalline structure, magnetic properties, and chemical composition. The resulting electrochemical sensor, CoFe2O4@CTS/GCE, was generated through a one-step modification of a glassy carbon electrode (GCE). Utilizing differential pulse adsorptive stripping voltammetry (DPAdSV), our proposed sensor exhibited high sensitivity, with low limits of detection (LOD) values of 0.04 and 0.31 μg L–1 (Ed = −1.0 V; td = 90 s) for lead and cadmium, respectively. The exceptional sensitivity observed is indicative of interactions between HMI and CTS amine groups, leading to the effective preconcentration of the analytes. Furthermore, our sensor demonstrated excellent selectivity with an interference response below 8.93% for Pb(II) and 20% for Cd(II). Accuracy was evaluated using SRM 1643e (NIST). The application of green analytical chemistry (GAC) metrics resulted in a score of 0.91, highlighting the environmentally conscious aspects of our methodology.