Development of highly selective electrochemical impedance sensor for detection of sub-micromolar concentrations of 5-Chloro-2,4-dinitrotoluene

摘要

A highly selective and sensitive impedimetric sensor based on molecular imprinted polymer (MIP)has been developed for the detection of 5-chloro-2,4-dinitrotoluene (5CDNT). Computational simulations werecarried out for the best combinations of MIP precursors by using Hyperchem software. MIP of 5CDNT issynthesized using the optimized combinations of polymer precursors such as the functional monomer and crosslinker.Synthesized MIP and non-imprinted polymer (NIP) were characterized by Fourier transform infraredspectroscopy (FT-IR) and BET adsorption isotherm analysis. The surface area and pore volume of MIP arequite high compared to that of NIP, while the average pore diameter of MIP is lower than that of NIP. However,the synthesized MIP with high surface area and quite good pore diameter for free flow of analytes is suitablefor efficient binding with the analyte 5CDNT.Binding assay studies of MIP by using UV-Visible spectroscopyshowed that the molecular imprinting factor is nearly thrice to that of NIP. Carbon paste electrodes incorporatedwith MIP were employed as a sensor for 5CDNT by applying electrochemical impedance spectroscopy (EIS)as transduction principle. The charge transfer resistance obtained by impedimetric analysis is proportional tothe concentration of 5CDNT over a wide concentration range: 10 nM to 100 ??M. A linear determination rangeof 1.0 to 100 ??M was obtained, and the low-detection-limit was found to be 0.1 ??M. The MIP carbon pasteelectrode has shown very good selectivity towards specific recognition of 5CDNT despite the coexistence ofpossible interferents like 2,4-dinitrotoluene and 1,3-dinitrobenzene. The present MIP based sensor system couldbe used successfully for direct determination of 5CDNT.