Researchers at The University of Texas at Austin have developed a way to fingerprint forever chemical pollution, which could help authorities trace them to their source when they end up in aquifers, waterways or soil.
Tracking forever chemical pollution involves passing samples through a strong magnetic field and then reading the burst of radio waves their atoms emit.
This reveals the composition of carbon isotopes in the molecule and gives the chemical its fingerprint, a feat that had not previously been achieved with forever chemicals.
According to Cornelia Rasmussen, a research assistant professor at the University of Texas Institute for Geophysics at the Jackson School of Geosciences, the work is important because it allows scientists to track the spread of forever chemicals in the environment.
It’s previously been difficult to track forever chemical pollution
The super strong molecular bonds that give forever chemicals their handy characteristics — which are put to use in everything from fire retardants to non-stick surfaces and slow-release drugs — also keep them from breaking down in the environment, causing them to build up as pollution in soil and organic material to which they easily stick.
The U.S. Environmental Protection Agency plans to regulate forever chemical pollution, which includes PFAS, and eliminate most of it from drinking water.
However, the molecular bonds of the chemicals also make them difficult to trace. Conventional chemical fingerprinting involves breaking molecules apart in a mass spectrometer, which doesn’t work well with the tough molecular bonds of forever chemicals.
Instead, the researchers turned to a technology called nuclear magnetic resonance (NMR) spectroscopy, which measures a molecule’s structure and identifies its isotopes without breaking it apart.
Determining a mix of carbon isotopes
Isotopes refer to chemical elements with differences in the number of neutrons in their atoms. Forever chemicals are made by bonding carbon isotopes to the element fluorine, which almost never happens in nature. Once the molecular bonds form, they are virtually unbreakable.
The researchers’ technique uses the NMR instrument alongside their own computational tools to determine the mix of carbon isotopes at each position in the molecule.
Because the mix of carbon isotopes bonding to each fluorine atom is unique to how the chemical was manufactured, this information can be used like a fingerprint to trace forever chemical pollution.
“Part of the reason this has worked out so well is because we’re assembling tools from different areas of science that don’t normally mix and using them to do something no one’s really done before,” explained David Hoffman, an associate professor at the Department of Molecular Biosciences in UT’s College of Natural Sciences.
Piloting the technique for commercial use
The researchers tested their technique on samples that included pharmaceuticals and a common pesticide. Rasmussen and Hoffman are now conducting a pilot study to see how the technique will fare on pollutants that show up in the city of Austin’s creeks and wastewater.
If successful, the technique could be useful for state and federal agencies who want to track the spread of water-borne forever chemical pollution.
Rasmussen said that the work has opened up a new layer of isotope information in organic chemistry that could find many applications beyond tracking forever chemicals, such as detecting counterfeit drugs or astrobiology.
