A Biomimetic Sensor with Signal Enhancement of Ferriferrous Oxide-Reduced Graphene Oxide Nanocomposites for Ultratrace Levels Quantification of Methamidophos or Omethoate in Vegetables

In this study, we designed and synthesized Fe₃O₄/reduced graphene oxide (Fe₃O₄/rGO) and MIL@MIP, which were characterized using transmission electron microscopy (TEM), X-ray diffraction, Fourier transform infrared (FT-IR), cyclic voltammetry (CV), and differential pulse voltammetry (DPV). Here, reports a novel biomimetic electrochemical sensor (BECS) sensitized with Fe₃O₄/reduced graphene oxide (Fe₃O₄/rGO) nanocomposite using MIL@MIP film as recognition element for ultrasensitive quantification of methamidophos or omethoate. The BECS offered fast responses for methamidophos and omethoate with wide linear response ranges of 1.0 × 10^?7–1.0 × 10^?12 and 1.0 × 10^?7–1.0 × 10^?13 mol/L, respectively. Under optimized conditions, the limit of detection (LOD; S/N = 3) of the BECS method was 2.67 × 10^?13 mol/L for methamidophos and 2.05 × 10^?14 mol/L for omethoate. The BECS was applied to detection of methamidophos and omethoate in spiked cucumber and kidney bean samples, and good recoveries varied from 88.2 to 96.9 %. This proposed method was adopted for the determination of the methamidophos or omethoate residues in the rape sample, and the results were also verified using the method of gas chromatography.