Rapid Characterization of Per- and Polyfluoroalkyl Substances (PFAS) by Ion Mobility Spectrometry–Mass Spectrometry (IMS-MS)

Per- and polyfluoroalkyl
substances (PFAS) are an ensemble of persistent
organic pollutants of global interest because of their associations
with adverse health outcomes. Currently, environmental PFAS pollution
is prolific as a result of the widespread manufacturing of these compounds
and their chemical persistence. In this work, we demonstrate the advantages
of adding ion mobility spectrometry (IMS) separation to existing LC-MS
workflows for PFAS analysis. Using a commercially available drift
tube IMS-MS, we characterized PFAS species and isomeric content in
both analytical standards and environmental water samples. Molecular
trendlines based on intrinsic mass and structural relationships were
also explored for individual PFAS subclasses (e.g. PFSA, PFCA, etc.). Results from rapid IMS-MS analyses provided
a link between mass and collision cross sections (CCS) for specific
PFAS families and are linked to compositional differences in molecular
structure. In addition, CCS values provide additional confidence of
annotating prioritized features in untargeted screening studies for
potential environmental pollutants. Results from this study show that
the IMS separation provides novel information to support traditional
LC-MS PFAS analyses and will greatly benefit the evaluation of unknown
pollutants in future environmental studies.