An organopalladium chromogenic chemodosimeter for the selective naked-eye detection of Hg(2+) and MeHg(+) in water-ethanol 1 : 1 mixture.

An organopalladium chemical dosimeter of Hg(2+) that methylates Hg(2+), undergoing a colour change in 1 : 1 ethanol-water with submicromolar sensitivity, gives rise to an aqua-palladium complex that is methylated by MeHg(+) in the presence of a dithiol compound, undergoing another colour change, thus making the system suitable for the naked-eye detection of Hg(2+) and MeHg(+), two environmentally important species of Hg(2+).