Identification of Per- and Polyfluoroalkyl Substances in the Cape Fear River by High Resolution Mass Spectrometry and Nontargeted Screening

Ongoing chemical
development in response to regulation of historical
perfluorinated compounds, (i.e., perfluorooctanoic acid (PFOA) and
perfluorooctanesulfonic acid (PFOS)) has resulted in a proliferation
of novel per- and polyfluorinated species. Screening and monitoring
for these emerging chemicals benefit from a nontargeted approach due
to a lack of necessary standards and a paucity of information about
the replacement chemistries. In this paper, we apply nontargeted screening
to the Cape Fear River of North Carolina, a fluorochemically impacted
watershed. The continued presence of perfluorinated ether acids was
confirmed, with a total of 37 unique chemical formulas comprising
58 isomers detected. Structural determination was carried out by LC-MS/MS
to determine isomeric structures where possible. Novel structures
determined included perfluorinated ether acid species containing two
acidic sites, polyfluorinated ether acids containing a single hydrogenation,
and previously unreported perfluorinated ether acids. Compounds identified
by an initial nontargeted screen were monitored over repeated sampling
to track long-term reductions in PFAS content during emission source
control. Hierarchical clustering of the time course data was used
to associate groups of chemicals based on their trends over time.
Six clusters were identified and showed some similarity in chemical
class; they are believed to represent the byproducts of different
fluorochemical production lines.