Browsing by Author "Lemmens, Shannon"

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    Characterizing the Occurrence and Fate of Micropollutants in Aqueous and Environmental Samples: A Multidimensional Approach
    (University of Waterloo, 2025-09-09) Lemmens, Shannon
    Emerging contaminants such as pharmaceuticals and per-and polyfluoroalkyl substances (PFAS) present persistent challenges for environmental monitoring due to their chemical diversity, trace-level occurrence and limited removal in conventional wastewater treatment. This thesis presents a dual approach combining experimental two-dimensional separations with computational modelling to advance contaminant detection and mechanistic understanding. A targeted liquid chromatography-mass spectrometry (LCxDMS-MS/MS) method was developed and applied to complex pharmaceutical mixtures, revealing improved compound differentiation and class-based clustering across orthogonal retention time and compensation voltage dimensions. These trends demonstrate the potential of LCxDMS-MS/MS as a selective, high-throughput workflow for micropollutant screening in aqueous matrices. Complementary to this, quantum chemical calculations were performed on PFAS molecules, specifically perfluorosulfonic acids (PFSAs), to elucidate degradation pathways and assess the influence of molecular conformation on fragmentation energetics. Calculations identified several concerted and non-concerted reaction pathways that contribute to product selectivity. Together, these efforts establish a framework that integrates instrumentation and theory to support more informed contaminant analysis and method development.