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

Abstract

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 were carried out for the best combinations of MIP precursors by using Hyperchem software. MIP of 5CDNT is synthesized using the optimized combinations of polymer precursors such as the functional monomer and cross-linker. Synthesized MIP and non-imprinted polymer (NIP) were characterized by Fourier transform infrared spectroscopy (FT-IR) and BET adsorption isotherm analysis. The surface area and pore volume of MIP are quite 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 suitable for efficient binding with the analyte 5CDNT. Binding assay studies of MIP by using UV-Visible spectroscopy showed that the molecular imprinting factor is nearly thrice to that of NIP. Carbon paste electrodes incorporated with 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 to the concentration of 5CDNT over a wide concentration range: 10 nM to 100 μM. A linear determination range of 1.0 to 100 μM was obtained, and the low-detection-limit was found to be 0.1 μM. The MIP carbon paste electrode has shown very good selectivity towards specific recognition of 5CDNT despite the coexistence of possible interferents like 2,4-dinitrotoluene and 1,3-dinitrobenzene. The present MIP based sensor system could be used successfully for direct determination of 5CDNT.