Electrochemical sensor based on Co3O4 and Au nanoparticles for simultaneous determination of As3+ and Hg2+ by stripping voltammetry

Nowadays, the monitoring of heavy metals in environmental samples, especially freshwater sources, is of global concern. Mercury (Hg) and arsenic (As) are known as heavy metals with high toxicity. They present high risks to both human health and the environment even at trace concentrations. Therefore, the development of sensitive, selective and fast monitoring methods for the measurement of metal ions is significant due to the increasing use of industries and the serious environmental effects of these heavy metals. In this work, a glassy carbon electrode (GCE) modified with cobalt oxide nanoparticles (Co₃O₄) and gold nanoparticles (AuNPs) characterized using scanning electron microscope (SEM) and anodic stripping voltammetry (ASV) and applied as a catalytic surface for the simultaneous detection of Hg²⁺ and As³⁺ ions in environmental water samples. Important parameters such as electrolyte type, electrolyte concentration, accumulation potential and accumulation time were systematically optimized. The catalytic surface as an efficient sensor exhibited an excellent linearity with wide dynamic range from 10 to 900 ppb for As³⁺ and 10 to 650 ppb for Hg²⁺. Recovery between 96% and 116% were obtained after the analysis of real samples: river and drinking water confirming the sensor's high accuracy and reliability.