Reviewed by Lexie CornerNov 7 2024
Researchers at the University of Massachusetts Amherst have discovered a novel method for identifying per- and polyfluoroalkyl compounds (PFAS) in water. This represents a significant advancement in developing testing tools that are easier to use, more affordable, quicker, and more widely accessible than current techniques. The study was published in the journal Science Advances.
PFAS, often referred to as "forever chemicals," are known to be dangerous contaminants. Their resistance to degradation allows them to persist in the environment, posing serious health risks. Exposure to these chemicals has been linked to liver and heart damage, developmental harm in newborns and children, and several types of cancer, including kidney, testicular, breast, ovarian, prostate, thyroid, and juvenile leukemia.
Earlier this year, the Environmental Protection Agency (EPA) issued the first-ever nationwide safety threshold for PFAS in drinking water, setting it at four parts per trillion (ppt).
PPT – that means parts per trillion. That means in a trillion molecules in water, only four molecules are PFAS. And then we need to be able to detect even those few.
Chang Liu, Associate Professor and Study Corresponding Author, Biomedical Engineering, University of Massachusetts
Mass spectrometry and liquid chromatography are the gold standards for PFAS testing. However, this process necessitates intricate extraction procedures and equipment worth millions of dollars, and it is also not transportable.
In addition, the stubborn persistence of PFAS residues can diminish the sensitivity of these instruments over time.
Xiaojun Wei, Study First Author and Research Assistant Professor, University of Massachusetts
Their study demonstrates that it is possible to identify different families of PFAS and detect these compounds at levels as low as 400 parts per trillion (ppt) using small, low-cost equipment. While this proof-of-concept invention does not achieve the same sensitivity or range of PFAS types detectable by mass spectrometry, the researchers see significant potential for its application.
We are bringing the cost of the instrument from the scale of a million dollars to a few thousand. We need better technology for detecting PFAS more accessible, more affordable, and easier to use. And more testing that is on site. That is the motivation.
Chang Liu, Associate Professor and Study Corresponding Author, Biomedical Engineering, University of Massachusetts
According to the researchers, this approach can also serve as a preliminary screening tool to identify which water sources pose the greatest risk to human health.
Their testing apparatus operates by introducing a chemical known as cyclodextrin into a nanopore, a small device commonly used for DNA sequencing. While the “host-guest” relationship between cyclodextrin and PFAS has been well-studied, Liu notes that no one has previously utilized a nanopore in conjunction with cyclodextrin for detection purposes.
“Now we are using one of these molecules called HP-gamma-Cyclodextrin as an adapter in an alpha-Hemolysin nanopore,” he said, effectively creating a PFAS detector.
Liu hopes that their study will raise public awareness of the dangers of PFAS and ultimately lead to the development of a portable, commercially available PFAS detector for field water monitoring.
Journal Reference:
Wei, X., et al. (2024) Single-molecule profiling of per- and polyfluoroalkyl substances by cyclodextrin mediated host-guest interactions within a biological nanopore. Science Advances. doi.org/10.1126/sciadv.adp8134.