Discovery of 40 Classes of Per- and Polyfluoroalkyl Substances in Historical Aqueous Film-Forming Foams (AFFFs) and AFFF-Impacted Groundwater

Aqueous film-forming foams (AFFFs),
containing per- and polyfluoroalkyl
substances (PFASs), are released into the environment during response
to fire-related emergencies. Repeated historical applications of AFFF
at military sites were a result of fire-fighter training exercises
and equipment testing. Recent data on AFFF-impacted groundwater indicates
that ∼25% of the PFASs remain unidentified. In an attempt to
close the mass balance, a systematic evaluation of 3M and fluorotelomer-based
AFFFs, commercial products, and AFFF-impacted groundwaters from 15
U.S. military bases was conducted to identify the remaining PFASs.
Liquid chromatography quadrupole time-of-flight mass spectrometry
was used for compound discovery. Nontarget analysis utilized Kendrick
mass defect plots and a “nontarget” R script. Suspect
screening compared masses with those of previously reported PFASs.
Forty classes of novel anionic, zwitterionic, and cationic PFASs were
discovered, and an additional 17 previously reported classes were
observed for the first time in AFFF and/or AFFF-impacted groundwater.
All 57 classes received an acronym and IUPAC-like name derived from
collective author knowledge. Thirty-four of the 40 newly identified
PFAS classes derive from electrochemical fluorination (ECF) processes,
most of which have the same base structure. Of the newly discovered
PFASs found only in AFFF-impacted groundwater, 11 of the 13 classes
are ECF-derived, and the remaining two classes are fluorotelomer-derived,
which suggests that both ECF- and fluorotelomer-based PFASs are persistent
in the environment.