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News / December 4, 2008

Fluorescence detects mercury in amalgam

by Guy Hiscott

US scientists have developed a simple and quick method for detecting mercury in fish and dental samples.

The technique – thought up by researchers at the University of Pittsburgh – involves a fluorescent substance that glows bright green when it comes into contact with oxidised mercury.

The intensity of the glow indicates the amount of mercury present.

Developed in the laboratory of Kazunori Koide, a chemistry professor in Pitt’s School of Arts and Sciences, the new method can be used onsite and can detect mercury in 30 to 60 minutes for dental fillings (or amalgams) or 10 to 30 minutes for fish.

Koide explained: ‘Our method could be used in the fish market or the dentist office. We have developed a reliable indicator for mercury that a person could easily and safely use at home.’

The fluorescence results from the reaction of mercury ions with hydrocarbons called alkynes – the alkyne is converted into a ketone and creates a fluorescent molecule.

Koide’s method differs from similar mercury indicators in that it withstands the oxidation process mercury samples must undergo prior to testing.

The mercury species found in most fish and dental amalgams – such as the toxic methyl mercury – must be converted into a safer variety of mercury with an oxidising agent.

Other fluorescent detectors are often not compatible with samples that have been oxidised.

In terms of amalgam disposal, Koide suggested that his method could be used to test dentist office wastewater for mercury content onsite without sending samples to analytical laboratories.

The researchers’ report is in the current online edition of the Journal of the American Chemical Society.