Development of Analytical Methods for the Detection of Legacy, Novel, and Emerging Environmental Contaminants

Environmental contaminants pose significant risks to ecosystems and human health. Analytical measurements are essential in environmental chemistry for assessing levels of contamination, identify emerging pollutants, and informing regulatory decisions. However, many traditional analytical techniques are time-consuming and expensive, posing challenges for large-scale sample analysis. This challenge highlights the opportunity for rapid, spectroscopy-based screening methods to improve sample through-put in analytical workflows. Additionally, the continuous emergence of new environmental contaminants requires the development of innovative analytical techniques, which can be guided by insights from screening methods. My dissertation work focuses on the integration of spectroscopy-based screening methods with traditional analytical methods to investigate three categories of environmental contaminants: lead, per- and polyfluoroalkyl substances (PFAS), and halogenated azobenzene disperse dyes (ADDs). In Chapter 2, I assess the performance of the Notre Dame lead screening kit, which employs x-ray fluorescence spectroscopy (XRF) to analyze lead in paint, dust, and soil samples from the home environment. The results are compared against the government gold-standard lead inspection and risk assessment (LIRA), which combines XRF and inductively coupled plasma (ICP) analysis. This work validates the lead screening kit as a low-cost, effective resource for assessing lead contamination in homes. In Chapters 3, 4, and 5, total fluorine screening via particle-induced gamma-ray emission (PIGE) spectroscopy is used to detect elevated fluorine concentrations in a series of wearable consumer products prior to targeted liquid chromatography, tandem mass-spectrometry (LC-MS/MS) analysis. Chapter 3 focuses on fluoroelastomer watch bands, where total F screening via PIGE determined 15 of the 22 samples contain fluoroelastomers a synthetic rubber consisting of polymeric PFAS. Targeted analysis detects the non-polymeric PFAS compound PFHxA in 8 of the 22 fluoroelastomer watch bands, suggesting that short-chain PFAS are used in fluoroelastomers manufacturing. Additionally, this chapter includes the first application of direct total oxidative precursor (dTOP) assay to solid sample matrices to determine the presence of PFAS precursors. Chapter 4 examines the presence of PFAS in feminine hygiene products, where total F screening indicates intentional PFAS use in 26 of 113 products, including 13 of 43 period underwear samples. Targeted analysis identified measurable PFAS concentrations in all 33 samples selected for further analysis and emphasized the utility of GC-MS analysis for detection of PFAS in textiles, as neutral PFAS were the most abundant of the measured PFAS. Chapter 5 continues the use of total F screening and targeted analysis in firefighter station wear, while also validating the use of particle-induced x-ray emission spectroscopy (PIXE) to screen for metals, flame retardants, and halogenated ADDs in textiles. While PFAS were detected in some samples, the analyses also show concerning levels of heavy metals and halogenated ADDs in station wear. Finally, Chapter 6 discusses the development of a non-targeted analysis method that identified 44 potential halogenated ADDs in station wear, providing further insight into the dyes used in textiles. Additionally, semi-quantitative non-targeted analysis was used to provide halogenated ADD concentration estimates, marking the first use of this methodology in dye analysis. Overall, this dissertation demonstrates how spectroscopy-based screening methods can complement traditional analytical techniques to improve workflow efficiency and expand contaminant detection capabilities. Furthermore, the identification of PFAS in watch bands, feminine hygiene products, and firefighter station wear highlights the widespread presence of these persistent chemicals in consumer products. These findings reinforce the urgent need for regulatory action and manufacturing changes to reduce human exposure.