Simultaneous detection of pesticides, carbendazim, and isoproturon using a novel nanocomposite based on graphene oxide/multi-wall carbon nanotube as an electrochemical sensor

This study demonstrates the fabrication of an electrochemical probe and superior performance in the simultaneous determination of two pesticides, carbendazim (CBZ) and isoproturon (ISO), using a modified glassy carbon (GC) electrode with a novel graphene oxide/multi-walled carbon nanotube (GO-MWCNT) nanocomposite for the first time. The existing hydrophilic properties of GO can facilitate the development of a stable dispersion of GO-CNT nanocomposite material through pi-pi stacking interactions for their intriguing electrochemical detection. This novel nanocomposite was completely characterized by XRD, FT-IR, SEM, and TEM techniques. The MWCNT were dispersed/spread over the crumpled GO nano-sheets, as confirmed by the TEM images. Their oxidation potentials and current are significantly varied with various modified electrodes, such as bare GCE, MWCNT, GO, and GO-MWCNT in 0.1 M PBS (pH 2) at 50 mVs(-1). The oxidation of ISO and CBZ on the GO-MWCNT-modified electrode has shown 3 and 5.2 times of current enhancement respectively, compared to the bare GCE. The feasibility of the proposed nanocomposite for the analysis has been shown by the observed maximum oxidation peak current recorded at pH 2. The cyclic voltammogram containing 0.1 mM of ISO and CBZ on the modified GO-MWCNT/GCE have yielded linear plots with the logarithm of scan rate vs peak potential with R2 values of 0.99 and 0.987 respectively, implying the occurred surface adsorption-controlled reaction process. Its reproducibility with 100 mu M of ISO and 10 mu M of CBZ has shown the related standard deviation for five experiments as 2.8 % and 1.58 % respectively. Moreover, the real sample analysis was optimized with GO-MWCNT/GCE by differential pulse voltammetry technique towards CBZ and ISO in the river and paddy water samples, and the recovery percentages were found to be 99-103 and 99.7-101.3 % respectively.