If you’ve ever been bamboozled by piecing together the atoms of a molecule in chemistry class, you’re in good company: Even professionals sometimes have a hard time understanding complex chemical structures. But thanks to a new scientific paper, clarity might soon be coming for an important class of toxic substances. Most people know them as “forever chemicals,” and scientists call them per- and polyfluoroalkyl substances (or PFAS for short). But regardless of the name that researchers use for these long-lived and harmful compounds, it can sometimes be hard for researchers to describe the molecular structure of a new PFAS when they find it. But it will get easier to clearly describe newly-detected PFAS thanks to research published today in Environmental Science & Technology Letters. In the publication, QAEHS scientists Prof Kevin Thomas, Dr Sarit Kaserzon and Dr Pradeep Dewapriya collaborate with a team of scientists from around the world to outline a framework for researchers to communicate with each other of how certain they are of a chemical structure when they identify a new or poorly characterised PFAS.
“PFAS include thousands of chemicals with a wide range of diverse chemical structures, but the atoms of a PFAS molecule could be put together via hundreds of possibilities”, explained Dr Sarit Kaserzon, QAEHS Senior Research Fellow. “This work aims to provide the framework for scientists to be able to consistently report how certain they are of how the atoms of a given PFAS fit together when identifying PFAS”. Communicating clearly the certainty of a chemical structure is important for newly discovered PFAS, because different PFAS structures with the same chemical formula may come from different sources, move through the environment differently, or harm human health in different ways.
The framework described in the publication outlines levels to clearly differentiate between very confident identifications of PFAS, scored at level 1, and more vague or uncertain identifications scored at level 5. “It’s akin to picking a suspect out of a police lineup,” said Colorado School of Mines Professor Chris Higgins, who was the paper’s senior author. “A level 5 identification might be the molecular equivalent of saying, ‘The bank robber escaped in a blue car,’ while level 1 provides an exact molecular structure, something like, ‘The bank robber escaped in a blue 2008 Nissan Sentra with a Nevada license plate and a broken left tail light.’ You’re much more likely to catch the bad guy.” The new confidence scale is expected to be most useful when scientists communicate PFAS that fall between these two extremes. For instance, when clearly identifiable chemical cousins are used to implicate the identity of a newly-discovered PFAS.
The article “Communicating Confidence of Per- and Polyfluoroalkyl Substance (PFAS) Identification via High Resolution Mass Spectrometry” was published in in Environmental Science & Technology Letters on 25th May, 2022.
