June 15, 2008 Researchers at the University of Massachusetts Amherst have developed plastics containing “smart elements” that can instantly detect the presence of mercury at or below the drinking water standard set by the U.S. Environmental Protection Agency, even when other metals are present in the solution.
“Mercury poisoning remains a significant threat to human health, and global mercury emissions continue to rise from incineration of solid waste and the combustion of fossil fuels,” says Gregory Tew, a professor of polymer science and engineering. “We used smart polymers to create inexpensive, portable and easy-to-use sensors that are a big improvement over current industrial approaches that use sophisticated equipment not suitable for field measurements.”
According to Tew, mercury has a long lifetime in the atmosphere, which tends to spread the contamination across wide areas of land and water. To make the problem worse, bacteria can convert different forms of mercury into methyl mercury, adding this potent neurotoxin to the food chain.
Funding for the project was provided by the Army Research Office. Results were published April 28 in Chemistry – A European Journal.
The sensors were created by coating cotton filter paper with a polymer containing terpyridine, a molecule that is known for its ability to bind to metals. After placing strips of the coated paper in water, Tew noticed an immediate color change to pink at a mercury concentration of 2,000 parts per billion. The color change was observed after one half-hour at a concentration of 2 parts per billion, which is the current drinking water standard.
Introduction of a ten-fold excess of competing heavy metals that can be found in contaminated environments such as copper, zinc, nickel and lead did not impact the ability of mercury to induce the pink color.
According to Tew, the dipsticks also solve many of the problems associated with portable sensors that rely on color or fluorescence, since the dip-sticks work well in water and can detect mercury in the presence of other metals, which are common failings of other methods.
Tew holds a patent for the mercury sensors, and is currently working with the UMass Amherst Office of Commercial Ventures and Intellectual Property to bring this product to market.
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