Rapid and on-site simultaneous electrochemical detection of copper, lead and mercury in the Amazon river

In poor and remote zones of the world, such as the Amazon region, the lack of analytical infrastructures prevents regular quality assessments of water systems. The access to affordable, portable and robust analytical technologies for real-time and on-site water monitoring is, therefore, key to safeguard vulnerable communities and the environment. In this context, we have developed and successfully implemented an electrochemical methodology for the rapid (60 s) and effective simultaneous electrochemical detection of heavy metal ions of concern (Pb²⁺, Cu²⁺ and Hg²⁺) in water, with a single screen-printed electrode probe. In particular, we show a wide quantification range for each pollutant (5−300 μg L⁻¹), and detection limits below the Environmental Protection Agency (EPA) maximum contaminant levels for drinking water: 0.015, 1.3 and 0.002 mg L⁻¹ for Pb²⁺, Cu²⁺ and Hg²⁺, respectively. The electrochemical sensors were tested in high temperature and humidity conditions in remote areas of the Amazon river, highly affected by mining-related heavy metal pollution. The field measurements were validated against standard lab-based analytical methods, showing excellent agreement. Our methodology can lead to an affordable and portable diagnostic tool for rapid and on-site monitoring of heavy metals pollution in remote areas.