Quick and accurate determination of hazardous phenolic compounds using CaCu2O3 nanorods based electrochemical sensor

Abstract

In the present work, we report the fabrication of a novel electrochemical sensor based on nanostructured CaCu2O3 as electrode material for the simultaneous determination of 2-Aminophenol (o-AP), 2-Chlorophenol (o-CP) and 2-Nitrophenol (o-NP). Nanorods-shaped CaCu2O3 have been synthesized by chemical precipitation method and characterized by powder X-ray diffraction (XRD), X-ray photo-electron microscopy (XPS), field emission electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM). Glassy carbon electrodes (3 mm diameter) have been modified using CaCu2O3 nanorods by drop-casting method. Cyclic voltammetry (CV) studies at CaCu2O3/GCE exhibited excellent electrochemical behaviours towards the oxidation of 2-AP, 2-CP and 2-NP at different potentials well separated from each other. The CaCu2O3/GCE displayed the lowest detection limits of 5.74 nM (0.626 ppb), 1.38 nM (0.177 ppb) and 1.03 nM (0.143 ppb) for 2-AP, 2-CP and 2-NP respectively over wide measurable linear ranges of 175 nM–68 μM (2-AP), 50 nM–90 μM (2-CP) and 25 nM–32 μM (2-NP). Cyclic stability studies showed a loss of 7%, 13% and 14% from initial current responses after conducting 100 cycles of CV for 2-AP, 2-CP and 2-NP in PBS (pH 7.0) which indicated the excellent stability of the fabricated electrode. Reproducibility studies of six different CaCu2O3/GCEs exhibited good recoveries in the order of 3.23% (2-AP), 3.54% (2-CP) and 2.46% (2-NP) respectively. The fabricated electrode with excellent sensitivity, stability and reproducibility has been successfully applied for the determination of 2-AP, 2-CP and 2-NP simultaneously in tap water and agricultural water samples. Selectivity studies carried out on CaCu2O3/GCE revealed its ability to detect 4-aminophenol and 4-nitorphenol at different oxidation potentials. High performance liquid chromatography (HPLC) studies have been carried out to validate the practical utility of the fabricated sensor.