Scandia-doped zirconia for the electrochemical detection of hazardous dihydroxybenzene (DHB) isomers in water.

In this paper, modified yttria- and scandia-doped zirconium oxide were exploited for the development of an effective electrochemical sensor for the simultaneous detection of dihydroxy benzene (DHB) isomers, i.e. hydroquinone (HQ), catechol (CC) and resorcinol (RS). A morphological and microstructural characterization, using scanning electron microscopy (SEM), infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and an electrochemical analysis, using electrical impedance spectroscopy (EIS), cyclic voltammetry (CV), and square wave voltammetry (SWV), of samples of zirconium oxide, zirconium oxide doped with 8% yttria and zirconium oxide doped with 10% scandium (ZrO₂, ZrO28Y, and ZrO210Sc, respectively), was carried out. Modified sensors were fabricated by using a screen-printed carbon electrode (SPCE). Electrochemical analysis conducted in phosphate buffer solutions (0.01 M PBS; pH = 7.4) showed the great ability of the ZrO210Sc/SPCE sensor to detect simultaneously DHB isomers with higher sensitivity than the other electrodes studied. SWV analysis performed with the ZrO₂10Sc/SPCE sensor showed the lowest limits of detection (LODs) among all sensors tested, with values of 0.92, 0.69, and 5.61 nM, for hydroquinone (HQ), catechol (CC), and resorcinol (RS) respectively. In addition, the sensor shows good repeatability and simultaneous detection capability for all DHB isomers. This sensor showed also excellent results for the detection of HQ, CC, and RS in tap and mineral water samples, with good recoveries (90-116%).