Detection of residual methomyl in vegetables with an electrochemical sensor based on a glassy carbon electrode modified with Fe 3 O 4 /Ag composite

Abstract

A magnetic Fe 3 O 4 /Ag composite with a core-shell structure was synthesized using a combination of Fe 3 O 4 nanoparticle coprecipitation and the reduction of Ag + on the surface of the Fe 3 O 4 nanoparticles by trisodium citrate. The as prepared Fe 3 O 4 /Ag composites was characterized by ultraviolet-visible absorption spectroscopy, and scanning/transmission electron microscopy (SEM and TEM). An electrochemical sensor was prepared by attaching the Fe 3 O 4 /Ag composites to the surface of a glassy carbon electrode (GCE) using chitosan (CS) as linking molecules. The concentration of methomyl in vegetables was measured using cyclic voltammetry (CV). The linear relationship was achieved in the concentration range of 3.47×10 -5 ~3.47×10 -4 mol·L -1 , with a correlation coefficient R 2 of 0.99707 and a detection limit of 2.97×10 -5 mol·L -1 .