Fabrication of an electrochemical sensor with an electrode modified by the two-separated steps of silver nanoparticle sensitizing and molecularly imprinted polymer coating for the selective and ultrasensitive determination of fenitrothion

Molecularly imprinted polymers (MIPs) were synthesized by sol-gel method using fenitrothion, (3-aminopropyl) triethoxysilane, and tetraethyl orthosilicate as template molecule, functional monomer, and cross-linker, respectively. The working electrode of the electrochemical sensor was prepared by fixing MIP on the surface of a silver nanoparticle modified-glassy carbon electrode with Nafion solution. The electrochemical properties of the working electrode were characterized by electrochemical impedance spectra, Fourier transform infrared spectroscopy, and cyclic voltammetry. The results showed that the MIP was successfully loaded onto a glassy carbon electrode, and the MIP electrode exhibited typical electrochemical differences compared with the non-molecularly imprinted polymers electrode. The electrochemical sensor based on the prepared MIP electrode shows a good analytical performance of fenitrothion. Influence factors on the preparation of the electrode (amount of MIP loaded, elution time) and analysis of fenitrothion (incubation time) were investigated. Under the optimized conditions, the differential pulse voltammetric peak current intensity showed good linearity with the concentration of fenitrothion in the range of 3.45 x 10(-11) M-3.45 x 10(-7) M with a low limit of detection (0.005 nM). The method was applied to the determination of fenitrothion in real samples with spiked recoveries of 97.4-102%.

Automated summary

Molecularly imprinted polymers (MIPs) were synthesized using sol-gel method with fenitrothion as the template molecule. The MIPs were fixed onto a silver nanoparticle modified-glassy carbon electrode to prepare the working electrode of an electrochemical sensor. The MIP electrode exhibited distinctive electrochemical properties and showed good analytical performance for fenitrothion. The method had a low limit of detection and was successfully applied to determine fenitrothion in real samples with satisfactory recoveries.