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Transformation and quantification of poly- and perfluoroalkyl substances
Gonda, Nicholas
Gonda, Nicholas
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2024
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Gonda_mines_0052E_12800.pdf
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Gonda_mines_0052E_316/Soils A_B_C PFAS Concentrations Final 11_26_23.xlsx
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Gonda_mines_0052E_316/Composite Significance Testing 11_26_23.xlsx
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Gonda_mines_0052E_316/Chapter 2 Supplementary Information.pdf
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Gonda_mines_0052E_316/Chapter 3 Supplementary Information.pdf
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2025-11-26
Abstract
Poly- and perfluoroalkyl substances (PFASs) are a class of manmade chemicals that have become infamous for their widespread environmental contamination, and adverse health effects in humans. Aqueous film forming foams (AFFFs) have been identified as one of the largest sources of PFASs to the environment. AFFF formulations are known to contain structurally diverse groups of PFASs. Perfluoroalkyl acids (PFAAs) are the most studied compound class amongst PFASs and are routinely measured. However, much of the fluorinated mass composing AFFFs often goes unmeasured. Additionally, evidence shows many non-PFAA fluorinated derivatives contained in AFFFs (precursors) are capable of transforming to PFAAs through a variety of pathways.
The first goal of this dissertation was to evaluate the relevance of precursor transformation via abiotic pathways. Photochemically generated hydroxyl radicals (•OH), dilute AFFF, and current high resolution mass spectrometry techniques (HRMS) were used to simulate and measure abiotic transformations of PFASs found in AFFFs. The results indicated fluorinated derivatives contained in AFFFs were capable of transforming to PFAAs with environmentally relevant doses of hydroxyl radical. Additionally, based on the observed rate constants between hydroxyl radical and AFFF-derived PFASs, abiotic transformations are expected to occur much faster than biotic transformations in specific environmental contexts (i.e. reduced iron rich subsurface sediments).
The second and third goals of this dissertation were to assess current and proposed analytical protocols on their abilities to quantify all PFASs (ΣPFASs) accurately and precisely at AFFF-impacted sites, particularly soils, where PFAS-relevant chemical diversity is usually the greatest. Three AFFF-impacted soil composites were analyzed using draft EPA Method 1633 (1633), a method proposed by Nickerson et al. 2020, and a new proposed methodology, the BAMBINO Method. Additionally, three other laboratories (2 commercial and 1 government) participated in analyzing the AFFF-impacted soil composites utilizing their own internally validated 1633 methodology. Results from these assessments indicate when 1633 is used to quantify ΣPFASs at AFFF-impacted sites, a large portion of the PFAS mass may be missed due to sample preparation bias and a narrow analyte list. The proposed BAMBINO Method yielded more accurate results in the context of ΣPFASs while retaining many methodological similarities with 1633. When the data for only the 1633 analyses were compared across four laboratories, results indicate low interlaboratory variation except for perfluorosulfonic acids (PFSAs). It is hypothesized that samples with abundant branched isomers likely increases variability between laboratories.
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