Scientists at Spain's University of Burgos developed a polymer known as JG25. That material has been incorporated into a probe, which is inserted into 2-gram flesh samples of various species of fish. After being left in contact for 20 minutes, it's then taken out and exposed to ultraviolet light. It responds by fluorescing blue – the more intense the color, the greater the amount of mercury present in the sample.The polymer reacts to the presence of both organic methylmercury, and inorganic Hg2+ mercury salt.

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