Advancing Non-Targeted Analysis of PFAS with Liquid Chromatography, Ion Mobility Spectrometry, and Mass Spectrometry

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  • Boatman, Anna Kathryn
    • College of Arts and Sciences, Department of Chemistry
Abstract
  • Per- and polyfluoroalkyl chemicals (PFAS) are man-made forever chemicals that are gaining increasing attention as global contaminants of concern due to their remarkable persistence, mobility, and toxicity. The PFAS class of chemicals is already large (14,000+ known molecules) and is growing as manufacturers face pressure to replace legacy PFAS with alternative structures. PFAS are structurally diverse and partition differently between water and tissue. Non-targeted analysis (NTA) is critical for detecting and identifying novel PFAS as well as monitoring more of these compounds than traditional targeted methods are capable of. In Chapter 1, a platform combining liquid chromatography, ion mobility spectrometry, and high-resolution mass spectrometry (LC-IMS-HRMS) is introduced for application to NTA of PFAS in environmental samples. In Chapter 2, fish fillet from three sites in North Carolina was assessed using the LC-IMS-MS NTA platform. Alarmingly high concentrations of PFOS were measured (site medians: 11.6 to 42.3 ppb) and an additional 35 PFAS were detected. Targeted methods would not have detected 19 of these PFAS, underscoring the importance of NTA as a complementary technique to quantitative methods. In Chapter 3, updated guidance for assigning confidence levels to PFAS identified using LC-IMS-HRMS was proposed. Existing guidance is ambiguous and does not incorporate the additional confidence that IMS data offers for PFAS identifications. A literature review revealed inconsistent application of current guidance across 38 PFAS NTA studies and emphasized the need for more objective, simpler guidelines. This framework will promote more transparent results reporting and improve the quality of PFAS identifications in this rapidly growing area of NTA research. In Chapter 4, alligators from a highly PFAS-contaminated region were sampled over 5 years and plasma was analyzed using complementary NTA approaches: library screening and a novel compound discovery workflow. Using the discovery workflow, structures for 12 PFAS not present in the library were elucidated, including 2 novel structures not previously reported and 3 compounds reported in patent literature but not detected previously in environmental samples. Altogether, this work provided insights into application of an LC-IMS-HRMS platform for NTA of PFAS in environmental samples and underscores the importance of NTA results.
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  • In Copyright - Educational Use Permitted
Advisor
  • Baker, Erin S
  • Glish, Gary L
  • Ehrmann, Brandie M
  • Belcher, Scott M
  • Knappe, Detlef
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2025
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