Simultaneous, ultrasensitive detection of hydroquinone, paracetamol and estradiol for quality control of tap water with a simple electrochemical method

Abstract

Real-time monitoring of possible contamination in the water supply network requires the deployment of large numbers of sensors for varied analytes, which would be economically viable only if simple methods and low-cost sensing units are available. In this paper, we demonstrate that carbon screen-printed electrodes (SPEs) can be used to determine simultaneously the presence of emerging pollutants (EP) hydroquinone (HQ), paracetamol (PARA) and estradiol (E2) in tap water, with detection limits of 185, 218 and 888 nmol L−1, respectively, within a linear range between 0.5 and 10.0 μmol L−1. This performance is competitive with high-performance liquid chromatography (HPLC), the gold-standard methodology for water analysis, being superior to any carbon-based electrochemical sensors in the literature. It was achieved with differential pulse voltammetry (DPV) using carbon SPEs pretreated through a simple procedure with cyclic voltammetry (CV) in 0.5 mol L−1 sulfuric acid solution. Pretreatment did not affect the electrode morphology but removed non-conducting residues from the printing ink, according to energy-dispersive X-ray (EDX) spectra obtained in scanning electron microscopy (SEM). Therefore, electrode conductivity increased as demonstrated in electrochemical impedance spectroscopy measurements. The pretreated SPEs were stable for at least 30 days and detection of the analytes was not affected by common interferents. Because the sensor fabrication and detection methods are simple, with potentially low-cost water analysis, the results presented here may inspire the design of sensor networks for monitoring water quality in the supply system and in the environment.