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.