Fe₃O₄ / lauric acid electrochemical sensor for rapid, selective and cost-effective microplastic detection in water

Microplastics(MPs) are a new class of persistent and recalcitrant pollutants that pose significant ecological and health threats, highlighting the critical need to develop efficient and straightforward detection techniques. In this study, an Fe₃O₄@lauric acid (La)-modified electrode-based MP sensing platform was designed by combining the high-performance MP adsorption material Fe₃O₄@La and electrochemical analysis. The Fe₃O₄@La composite was synthesized using the liquid-phase deposition method from Fe₃O₄ and lauric acid to capture polystyrene (PS) MPs. Ferrocene (Fc) signal molecules were subsequently adsorbed onto the active sites of the captured MPs, and quantification was achieved via differential pulse voltammetry (DPV). This strategy leverages the hydrophobic and electronegative characteristics of the target, ensuring high selectivity and maintaining strong performance despite the presence of cations, anions, and organic substances. The sensor exhibited good linearity within the MP concentration range of 5 - 500 μg/L, achieving a low detection limit (LOD) of 1.91 μg/L. In the analysis of real samples, the method demonstrated satisfactory spike recovery ranging from 89.0% to 107.1%, with relative standard deviations (RSDs) ≤ 8.03%. This study provides a sensitive, rapid, and cost-effective approach with significant potential for detecting MPs in water.