High-Throughput Trace-Level Suspect Screening for Per- and Polyfluoroalkyl Substances in Environmental Waters by Peak-Focusing Online Solid Phase Extraction and High-Resolution Mass Spectrometry

Per- and polyfluoroalkyl substances
(PFASs) occur widely in environmental
waters. PFAS risk assessment necessitates the identification of unanticipated
PFASs at trace levels and therefore requires determinative methods
with nanogram per liter detection limits and the ability to provide
detailed molecular and structural information for nontargeted molecules.
High-resolution mass spectrometry (HRMS) enables comprehensive PFAS
characterization but is currently limited by low-throughput sample
preparation techniques that are prone to interference and analyte
losses due to sample handling and manual mass spectral interpretation
approaches. Here we report the development of a peak-focusing, online
solid phase extraction–HRMS method for suspect screening analysis
of PFASs in environmental waters. The realized method utilized 6 mL
of sample and required <40 min of instrument time for extraction
and HRMS analysis. Method evaluation using 45 model PFASs revealed
typical method detection limits of 0.1–4 ng L–1. The accuracy and precision on repeated analysis of a standard reference
material were typically 89–103% and <10%, respectively.
A suspect screening approach using an extensive PFAS molecular database
and computational mass spectrometry was demonstrated through the analysis
of aqueous film-forming foam-impacted surface water samples. Results
indicate that the developed methodology is suitable for high-throughput
and sensitive molecular annotation of diverse PFASs in environmental
waters.