Mercury pollution of drinking water sources by artisanal and small-scale gold mining activities is a health threat for rural communities in many regions of the world. Globally >10,000,000 people work in unregulated gold mining, where mercury is used to extract gold from ore, which leads to mercury contamination of local water sources.

To detect mercury pollution special equipment and training is required both of which is unavailable in rural communities. Instead, easy to use sensing tools are sought that allow communities to assess the safety of their drinking water sources over time. Former CSCT PhD student Carlos López-Alled, graduated in 2019, has developed a molecule that changes colour if mercury is present in water. The developed molecule can be manufactured at low cost in a two-step process, its response to mercury is rapid and sensitive enough so that the colour change can be discerned unambiguously without the need for a laboratory setting, an expert user, or a power supply. The molecule has also an excellent selectivity for mercury over other anions commonly present in drinking water.

The results of this collaborative research between research groups at Bath in Chemistry (Simon Lewis and Tony James) and Chemical Engineering (Jannis Wenk) were published recently in the RSC journal Analyst. The utilized molecular platform is versatile and can be customised to detect other water contaminants, as the WIRC/CSCT researchers have shown in a series of publications by first authors Carlos López-Alled and Lloyd Murfin, a current EPSRC DTP student in the Lewis group. Examples include fluoride and nitrite.The platform has also been employed to detect cytotoxic reactive oxygen and nitrogen species. Ongoing work includes expanding application to a wider range of difficult to detect drinking water contaminants, to environmental sampling for ocean research and to further simplify handling by immobilising the molecule on paper and in gels.