LC-QTOF Tracks PFAS Partitioning in LNAPL, Water
Mireia Roig-Paul and Jennifer Field of Oregon State University discuss with LCGC International how liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF) and 19F nuclear magnetic resonance (NMR) reveal how PFAS partition between light nonaqueous phase liquid (LNAPL) and groundwater.
At military bases, per- and polyfluoroalkyl substances (PFAS) often show up in the ground alongside a different kind of pollution — a layer of oily liquid, like fuel, that floats on groundwater rather than mixes with it. Researchers wanted to understand how these “forever chemicals” move between that oily layer and the groundwater underneath it, so they collected 13 matched pairs of oil and groundwater samples from monitoring wells and compared how concentrated the chemicals were in each. To identify and measure specific PFAS chemicals, they used liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF) to separate and detect compounds based on their chemical makeup. They also used a specialized magnetic resonance technique to measure the total amount of fluorine-containing organic material, since PFAS chemicals are built around fluorine atoms, and a related method to figure out how much of the oily layer was made up of aromatic (ring-shaped) compounds.