Selective amperometric flow-injection analysis of carbofuran using a molecularly-imprinted polymer and...

Herein, we propose a new approach for selective determination of carbofuran (CBF) in vegetables, based on a simple flow-injection system using a molecularly-imprinted amperometric sensor. The sensor design is based on a carbon-paste electrode decorated with carbon nanotubes and gold-coated magnetite (CNTs-Fe₃O₄@Au/CPE) coated with a molecularly-imprinted polymer (MIP) for CBF sensing. The MIP was synthesized on the electrode surface by electropolymerization using a supramolecular complex, namely 4-ter-butylcalix [8] arene-CBF (4TB[8]A-CBF), as the template. We used o-phenylenediamine as the functional monomer. Our results demonstrate that incorporation of the MIP coating improves the electrochemical catalytic properties of the electrode, increases its surface area, and increases CBF selectivity by modulating the electrical signal through elution and re-adsorption of CBF. The imprinted sensor (MIP-CNTs-Fe₃O₄@Au/CPE) was used in a flow-injection analysis (FIA) system. Experimental conditions were investigated in amperometric mode, with the following optimized parameters: phosphate buffer solution (0.1M, pH 8.0) as the carrier, flow rate 0.5mLmin^-1, applied potential +0.50V. When used in the FIA system, the designed imprinted sensor yields a linear dynamic range for CBF from 0.1 to 100µM (r² = 0.998) with a detection limit of 3.8nM (3S_b), and a quantification limit of 12.7nM (10S_b). The sensor exhibits acceptable precision (%RSD = 4.8%) and good selectivity toward CBF. We successfully applied the electrode to detect CBF in vegetable samples.