Electrochemical Sensors Based on Graphene Oxide for Real-Time Detection of Heavy Metal Contaminants

Abstract

The contamination of water systems with heavy metals also poses a high environmental and population health risk, and the World Health Organization (WHO) has reported acceptable concentrations of lead (Pb²⁺) and cadmium (Cd²⁺) in drinking water at 10 ppb and 6 ppb, respectively. Traditional methods of detection, such as atomic absorption spectroscopy and inductively coupled plasma mass spectrometry, though very sensitive, may require expensive equipment and be conducted in a laboratory for real-time monitoring. This research paper presents the design of graphene oxide (GO)-based electrochemical sensors for rapid, on-site detection of heavy metal ions. The sensing platform was prepared by drop-casting graphene oxide onto a glassy carbon electrode using a modified Hummers method. Differential pulse anodic stripping voltammetry (DPASV) was used to measure electrochemical performance. The GO-modified electrode had a linear detecting range of 1–200 ppb for Pb²⁺ and 0.5–150 ppb for Cd²⁺ with limits of detection (LOD) of 0.32 ppb and 0.21 ppb, respectively. The sensitivity was increased by 42% compared to bare electrodes, due to the increased surface area and the high concentration of oxygen-containing functional groups. The sensor was highly selective, with signal interference from coexisting ions (Zn²⁺, Cu²⁺, Hg²⁺) less than 5%, and it retained 93% of its original response after 30 days, indicating high stability. The results show that GO-based electrochemical sensors can provide cost-effective, sensitive, and portable real-time monitoring of heavy metals. The actual detection limits are much lower than the WHO-prescribed standards, suggesting their potential use in environmental surveillance and in protecting people's health.