Transformation of Fluorotelomer Carboxylic Acids and the Development of Methods to Analyze Total Fluorine in Complex Environmental Matrices

Per- and polyfluoroalkyl substances (PFAS) represent a class of synthetic compounds widely utilized in consumer products and prevalent across various environmental matrices. They are typically analyzed individually or comprehensively as a chemical family, primarily identified by their abundant fluorine content. Over the last two decades, there has been a notable trend towards utilizing partially fluorinated PFAS, which emulate the characteristics of fully fluorinated terminal PFAS but are subject to less stringent regulatory oversight. To provide context for experimental work, Chapter 1 introduces the dissertation’s objectives and overarching research questions, while Chapter 2 presents a comprehensive review of PFAS and fluorine analysis techniques. This review highlights current methodological strengths, limitations, and key parameters, laying the groundwork for the two primary research projects. The first project, described in Chapter 3, investigates the ambient transformation of PFAS precursors. It begins by exploring an elimination pathway under controlled laboratory conditions using a base, establishing a baseline understanding of the reaction. A similar experiment is then conducted using a consumer-grade cleaning agent, demonstrating that comparable transformation is possible in indoor environments. Using both targeted and non-targeted analysis, the study reveals challenges in accurately assessing PFAS composition and species abundance due to the transformation of precursors to terminal PFAS. The second project, detailed in Chapter 4, focuses on developing analytical methods for total fluorine (TF) detection using Particle-Induced Gamma-ray Emission (PIGE) spectrometry, a relatively novel technique in PFAS analysis that lacks standardized protocols for this chemical class. Despite this, PIGE demonstrated promising results comparable to those of established analytical instruments. Successful TF analysis methods were applied to various matrices relevant to PFAS treatment, including granular activated carbon, Ottawa sand, and brass. Finally, Chapter 5 synthesizes the dissertation’s findings, discusses broader implications, and identifies opportunities for future PFAS research.