A sensitive electrochemical nanosensor based on iron oxide nanoparticles and multiwalled carbon nanotubes for simultaneous determination of benzoquinone and catechol in groundwater

Benzoquinone (BQ, 1,4-dihydroxybenzene) and catechol (CC, 1,2-dihydroxybenzene) are considered as emerging microcontaminants due to their persistent toxicity for plants and animals. Therefore, it is of great importance to monitor these contaminants in groundwater. This work proposes a novel sensor based on a multiwalled carbon nanotubes functionalised with carbonyls, and iron oxide nanoparticles (MWCNT-COOH/Fe2O3) for simultaneous determination of BQ and CC. The nanomaterials were characterised by Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and Cyclic Voltammetry (CV). The electrochemical determination of BQ and CC has been studied using differential pulse voltammetry (DPV) technique on glassy carbon electrode (GCE) modified with MWCNT-COOH/Fe2O3 nanocomposite (MWCNT-COOH/Fe2O3/GCE). The developed new method under optimised experimental conditions was applied successfully for the simultaneous determination of BQ and CC in spiked underground water sample, pH 5.0 (Britton Robson - BR buffer). For DPV measurements, the following parameters were used after optimisation: E-initial = 0.0 V, E-final = 0.40 V; scan rate = 0.01 V s(-1) and pulse amplitude = 0.07 V. The linearity range of both analytes BQ and CC was 8-100 mu mol L-1 with limits of detection (DLs) of 3.46 mu mol L-1 and 1.52 mu mol L-1, respectively. Good average results of recovery (n = 3) were obtained in spiked environmental samples for BQ (sample 1: 98.16%; sample 2: 100.55%) and CC (sample 1: 97.44%; sample 2: 97.84%), with precision (relative standard deviation) of 4.5% and 5.6%, respectively.