Identification of novel non-ionic, cationic, zwitterionic, and anionic polyfluoroalkyl substances using UPLC-TOF-MSE high-resolution parent ion search.

Poly- and perfluoroalkyl substances (poly- and per-PFASs) are a large group of organic compounds that have become the target of investigation due to their widespread occurrence in the environment and biota, coupled with their known or suspected impacts on human health. Recent studies have shown that a significant portion of poly-PFASs remain unidentified. This study presents a time-of-flight mass spectrometry approach based on continuously interleaving scans at low and high collision energies (ToF-MSE) for the rapid identification and characterization of unknown PFASs. The MSE mode allowed for the simultaneous acquisition of full-spectrum accurate mass data of both parent and fragment ions in a single chromatographic run. Specific to PFASs, the hypothesis that PFASs can be selectively detected by the ToF-MSE high-resolution parent-ion search (HRPIS) of their characteristic fragments was confirmed with certified standards of 24 poly- and per-PFAS. After being validated with these certified standards, the innovative HRPIS approach was applied to a group of commercial surfactants, which led to the identification of 47 new and 43 infrequently reported PFASs, including 40 non-ionic, 30 cationic, 15 zwitterionic, and five anionic compounds. It is envisaged that the results, especially the identification of new non-ionic PFASs, may provide important insights into the historical occupational and non-occupational exposure to PFASs from the production and application of these surfactants.