This work presents a signal on-off ratiometric electrochemical sensor coupled with a molecular imprinted polymer (MIP) for imidacloprid (IMI) determination. The ratiometric strategy corrects the detection results by setting 6-(Ferrocenyl)hexanethiol (FcHT) as an internal reference. The MIP membrane, as a molecular recognition receptor, has a three-dimensional structure and is complementary in the shape and chemical functionality to the template. The combination of a ratiometric strategy and MIP improves the sensitivity and selectivity of the sensors. The experimental parameters, such as monomer/template ratio, electropolymerization cycle and adsorption time, are optimized to improve the IMI sensing performance of the as-fabricated electrode. Under optimal electrochemical conditions, the proposed sensor is used to detect IMI in laboratory and real samples. In a range as wide as 5 × 10-7-1 × 10-4 mol L-1, a linear relationship is well established, and the value of the correlation coefficient is 0.9984. The limit of detection (LOD, S/N = 3) is well defined as 4.7 × 10-8 mol L-1. The recovery rates range from 97.4% to 103.5% while testing real samples. The fabricated electrode shows superior anti-interference ability for IMI determination in the presence of analogs at a higher level.
Keywords: Electrochemical sensor; Imidacloprid; Molecularly imprinted polymer; Ratiometric strategy.
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