Fluorescing polymer in contact with different fish samples. Image credit: t. Torraba et al./ChemComm)A fluorescent polymer developed at the University of Burgos, Spain, detects the presence of methylmercury and Hg2+ salt in fish samples.

The polymer, JG25, was incorporated into a portable probe and applied to 2 g samples of different fish species. A qualitative relationship between Hg levels in fish and increased polymer fluorescence was verified by inductively coupled plasma mass spectrometry.

Analyses confirmed that the larger the fish, the higher the Hg levels. Swordfish, tuna, and dogfish contained 1.0-2.0 ppm, while conger eels contained 0.5 ppm. No Hg was detected in farmed salmon, indicating a lack of industrial or natural contaminant sources affecting species raised in captivity.