Rapid Characterization of Emerging Per- and Polyfluoroalkyl Substances in Aqueous Film-Forming Foams Using Ion Mobility Spectrometry–Mass Spectrometry

Aqueous film-forming foams (AFFF)
are mixtures formulated with
numerous hydrocarbon- and fluoro-containing surfactants. AFFF use
leads to environmental releases of unknown per- and polyfluoroalkyl
substances (PFAS). AFFF composition is seldom disclosed, and their
use elicits concerns from both regulatory agencies and the public
because PFAS are persistent in the environment and potentially associated
with adverse health effects. In this study, we demonstrate the use
of coupled liquid chromatography, ion mobility spectrometry, and mass
spectrometry (LC-IMS-MS) to rapidly characterize both known and unknown
PFAS in AFFF. Ten AFFF formulations from seven brands were analyzed
using LC-IMS-MS in both negative and positive ion modes. Untargeted
analysis of the formulations was followed by feature identification
of PFAS-like features utilizing database matching, mass defect and
homologous series evaluation, and MS/MS fragmentation experiments.
Across the tested AFFF formulations, we identified 33 homologous series;
only ten of these homologous series have been previously reported.
Among tested AFFF, the FireStopper (n = 85) contained
the greatest number of PFAS-like features and Phos-Check contained
zero. This work demonstrates that LC-IMS-MS-enabled untargeted analysis
of complex formulations, followed by feature identification using
data-processing algorithms, can be used for rapid exposure characterization
of known and putative PFAS during fire suppression-related contamination
events.