Application of a Gold /Poly(Congo Red) Modified Electrochemical Sensor Toward Fast and Reliable Detection of the Oxazolidinone Fungicide Famoxadone in Vegetables

In this work, the synthesis and optimization of an electrochemical sensor based on gold nanoparticles (AuNPs)/ conducting poly Congo red dye (poly(CR)) nanocomposite is reported and applied for detection of the Oxazolidinone fungicide famoxadone (FAM), which is considered as an environmentally hazardous material on excessive uncontrolled application. The modified sensor was characterized electrochemically using Cyclic Voltammetry (CV) and electrochemical impedance spectroscopy (EIS) to investigate the nature of charge transfer upon modification. Also, the topography of the sensor was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and energy dispersive X-ray spectroscopy (EDX). Two linear ranges 0.001–1 μM (0.37–374.40) μg l−1and 3–100 μM (1.12–37.44) mg l−1were recorded using AuNPs/poly (Congo Red)/GCE sensor for FAM with limit of detection (LOD) of 0.17 nM (0.06 μg l−1) and limit of quantification (LOQ) of 0.48 nM (0.18 μg l−1). The tested sensor showed good stability, reproducibility, and repeatability, in addition, sufficient selectivity towards FAM in presence of other tested pesticides. Finally, the fabricated sensor was applied for the determination of FAM in vegetable and formulation samples, with recovery range 98.9%–105.4% and RSD 0.70%–4.46%. ). Thus, this approach can be efficiently applied in regulatory authorization for tracing the Fam concentration, being very simple, portable, cost effective and easy to operate compared to chromatographic detection, thus allows fast decisions for regulatory authorities.