A highly selective colorimetric aqueous sensor for mercury

A new colorimetric mercury sensor is reported based on binding to terpyridine derivatives. It is able to selectively detect Hg-II ions over a number of environmentally relevant ions including Ca-II, Pb-II, Zn-II, Cd-II, Ni-II, Cu-II, and others. The response time upon exposure to Hg-II is instantaneous. By the naked eye, the detection limit of Hg-II is 2 ppm (25 mu M) in solution. With a spectrometer, this detection limit is increased down to 2 ppb (25 nM), which is the current EPA standard for drinking water. The significant problem of mercury poisoning requires new methods of detection that are sensitive and selective. Here we report a new simple system that takes advantage of the unique optical properties generated by terpyiridine-Hg complexes.