Differential ratiometric molecularly imprinted electrochemical method for methyl-parathion and carbendazim in foods

Non-specific adsorption of interferents on molecularly imprinted polymer (MIP) membranes bottlenecks their selective recognition to templates. Herein, we reported an improved differential MIP strategy to correct such adverse effect for determining carbendazim (CBZ) and methyl-parathion (MP) in food samples. MIP membranes of CBZ and MP were prepared using mixed functional monomers of β-cyclodextrin and thionine with synergistic recognition selectivity. Co₃O₄NPs@CNTs nanocomposites were used for signal amplification with the oxidation currents of CBZ and MP enhanced 16.5-fold and 14.9-fold, respectively. With the current of poly-thionine (at -0.292 V) in MIP as reference signal, the ratiometric current differences between MIP_-MP and MIP_-CBZ at 0.223 and 0.611 V were used in the determination of MP and CBZ with the detection limits of 1.6 and 2.5 nM, respectively. The interference levels in the improved differential MIP mode were - 13 % ∼15 % of those obtained in the standard MIP mode, strengthening the anti-interference ability of MIP-based sensors.