Electrochemical impedimetric enzyme-less detection of non-electroactive organophosphate pesticides using zirconium metal organic framework

Abstract

Residues of pesticides found in fruits and vegetables pose a grave risk to organisms, potentially causing acute and chronic diseases when their levels surpass the maximum residual limits (MRLs) for human consumption. This study targeted to detect non-electroactive organophosphate pesticides (OPPs), including malathion, dimethoate, chlorpyrifos, monocrotophos, and glyphosate using a zirconium-terephthalic acid combined metal organic framework (Zr-BDC) by electrochemical impedance spectroscopy (EIS). Comprehensive analysis of the synthesized Zr-BDC showed an extensive specific surface area of 868 m(2)g(-1). Nyquist plots and equivalent circuit models confirmed the higher adsorption of OPPs with P = S and P-S (malathion, dimethoate, chlorpyrifos) onto glassy carbon modified by Zr-BDC (Zr-BDC/GCE), in contrast to OPPs with P = O (monocrotophos, glyphosate, and nonOPPs). The Zr-BDC/GCE displayed a linear detection range of 5.0 nM to 70.0 mu M, with limit of detections (LODs) of 3.6, 4.1, 4.5, 3.8, and 4.3 nM for malathion, dimethoate, chlorpyrifos, monocrotophos, and glyphosate respectively. The sensor exhibited notable recovery 91.0 - 98.6 % and RSDs 1.19 - 1.97 % (n = 3) when tested with real samples (apple and cabbage) and demonstrating substantial reproducibility and long-term stability.