Electrochemical sensor based on molecularly imprinted polymer for sensitive and selective determination of metronidazole via two different approaches

A molecularly imprinted polymer decorated glassy carbon electrode (MIP/GCE) is facilely developed into an electrochemical sensing platform for detection of metronidazole (MNZ). MIP preparation was carried out via in situ electropolymerization and o-phenylenediamine was selected as the optimal functional monomer. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to characterize and assess the performance of the so-obtained sensor. In particular, two assay methods, which are based on different principles, were involved in the detection procedure. One is based on MIP/catalysis (Method І) and the other is MIP/gate effect (Method II). Comparison of these two methods was made in the aspects including detection range, sensitivity, accuracy, selectivity, repeatability, and long-term stability. It is found that Method І affords a lower detection limit of 3.33 × 10−10 M (S/N = 3) while the detection limit of Method II is 6.67 × 10−10 M (S/N = 3). The linear range of Method І and II is 1.0 × 10−9 to 1.0 × 10−8 M and 2.0 × 10−9 to 1.0 × 10−7 M, respectively. The MIP/GCE exhibits good recognition ability towards the template molecule-MNZ in the presence of the analogues of MNZ and other interferents, which can be ascribed to the successful imprinting effect during MIP membrane preparation.