A Rapid and Selective Electrochemical Sensor Based on Zincon/MWCNT@SPE for Zinc Detection in Aquatic Biota

Introduction/Objective: This study presents a simple, rapid, and effective electrochemical approach for the detection of Zn(II) in fish liver samples (Mugil cephalus) using a Zincon–multiwalled carbon nanotube modified screen-printed electrode (Zincon/MWCNT@SPE). Methods: Electrochemical techniques, including Cyclic Voltammetry (CV), Square Wave Voltammetry (SWV), and Electrochemical Impedance Spectroscopy (EIS), were employed for method optimization and performance evaluation. Electrolyte type and concentration were systematically examined, and 0.1 M KCl was identified as the most suitable supporting electrolyte. Results: The Zincon/MWCNT@SPE exhibited lower charge-transfer resistance, improved reversibility, and higher peak currents. The method exhibited excellent linearity (R² = 0.9978) in the concentration range of 1–100 μM, with limits of detection and quantification of 0.41 μM and 1.25 μM, respectively. Good repeatability (RSD = 3.53%) and precision were achieved, and results demonstrated close agreement with ICP-OES in the analysis of a real fish liver sample. Discussion: Optimization and electrochemical evaluation confirmed the enhanced performance of Zincon/MWCNT@SPE for Zn(II) detection. The improved electron-transfer properties and the reliable analytical response demonstrated that the proposed sensor is suitable for trace-metal analysis in biological tissues. Conclusion: The developed electrochemical method offers a sensitive, fast, and reliable strategy for Zn(II) detection. The sensor demonstrated strong analytical performance and practical applicability for real biological samples, highlighting its potential for routine environmental and food monitoring.