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<p>  </p> <p>Atmospheric aerosols formed through primary emissions, secondary gas-particle formations, and multi-phase chemical processes are composed of solid, semi-solid, or liquid-like particles suspended in the air that have direct implications towards the global radiative balance and human health as air pollutants.  Direct emissions of primary organic aerosols (POA; e.g. soot, BrC) and multi-phase formation of secondary organic aerosols (SOA) from the oxidation of biogenic monoterpene isomers represent two important sources/classes of particulate matter in the atmosphere. Multi-phase chemical processes driving the atmospheric and environmental aging through the photochemistry of iron(III), FeIII in organic aerosol particles and aqueous media drives the multiphase chemistry leading to systematic aging of their chemical composition and modifications to resulting light-absorption properties. The molecular composition, organic structures, physical properties, and sources of emissions are complex requiring development of powerful multi-modal analytical metrology, such as high-resolution mass spectrometry (HRMS) hyphenated with liquid chromatography (LC), photodiode array optical detection, drift tube ion mobility (IM) spectrometry, and desorption and ambient ionization of multi-components mixtures in atmospheric particles using temperature programmed desorption Direct analysis in real time (TPD-DART). Disseminating the molecular-specific composition, chemical and physical properties of complex mixtures in atmospheric organic particles and mixed inorganic/organic systems will help improve our understanding of their formation mechanisms, transformative chemical ageing processes, as well as improved detection of individual components in complex mixtures. </p> <p>     </p> <p>Chapter 1 and 2 of dissertation introduces complexity of atmospheric organic, carbonaceous aerosols, and complex environmental mixtures and discusses analytical metrology, experiments, and data analysis procedures used for detailed molecular-level characterization of mixtures. Chapter 3 the development of a robust analytical method for untargeted screening and determination of the physical and chemical properties (e.g. vapor pressures, enthalpies of sublimation, and saturation mass concentrations) of single components out of complex SOA particles using temperature programmed desorption Direct analysis in real time ionization – high resolution mass spectrometry (TPD-DART-HRMS).  Chapter 4 introduces the use of ion mobility - mass spectrometry (IM-MS) separation and multidimensional characterization of structural isomers in complex SOA mixtures. The chapter discusses the advanced usage of IM-MS to investigate the molecular and structural properties of isomers of alpha-pinene and limonene derived SOA, use of advanced data analysis procedures to resolved complex conformational and structural isomers, and investigate single-molecule structural changes from atmospheric-like ageing in SOA particles using IM-MS.  Chapter 5 discusses the chemical characterization and analysis of individual brown carbon (BrC) chromophores out of mixture of colorless organic carbon constituents and insoluble soot particles generated from controlled flame combustion of ethane fuel, a surrogate system representing gasoline combustion of motor vehicles. The chapter focuses on the quantitative method development and use of state-of-the-art liquid chromatography coupled to photodiode array followed by dopant assisted atmospheric pressure photoionization and HRMS (LC-PDA-HRMS) analysis, followed by conversion to quantitative optical information for comparisons with retrieved literature reports. Chapter 6 examines the complex multiphase photochemical cycling of Fe(III)-citrate, a relevant proxy for [FeIII-carboxylate]2+ complexes in atmospheric water using complementary analytical metrology of optical spectroscopy, LC-PDA-HRMS, oil immersion flow microscopy. Multi-modal datasets from these complementary techniques provide a unique experimental description of various stages of FeIII-citrate photochemistry, elucidate individual components of this reacting system, determine mechanistic insights, and quantify environmental parameters affecting the photochemistry. </p>

<p>This dissertation focused on the development of mass spectrometric methodologies, separation techniques, and engineered devices for the optimal analysis of complex mixtures relevant to the energy sector, such as alternative fuels, petroleum-based fuels, crude oils, and processed base oils. Mass spectrometry (MS) has been widely recognized as a powerful tool for the analysis of complex mixtures. In complex energy samples, such as petroleum-based fuels, alternative fuels, and oils, high-resolution MS alone may not be sufficient to elucidate chemical composition information. Separation before MS analysis is often necessary for such highly complex energy samples. For volatile samples, in-line two-dimensional gas chromatography (GC×GC) can be used to separate complex mixtures prior to ionization. This technique allows for a more accurate determination of the compounds in a mixture, by simplifying the mixture into its components prior to ionization, separation based on mass-to-charge ratio (<i>m/z</i>), and detection. A GC×GC coupled to a high-resolution time-of-flight MS was utilized in this research to determine the chemical composition of alternative aviation fuels, a petroleum-based aviation fuel, and alternative aviation fuel candidates and blending components as well as processed base oils.</p> Additionally, as the cutting edge of science and technology evolve, methods and equipment must be updated and adapted for new samples or new sector demands. One such case, explored in this dissertation, was the validation of an updated standardized method, ASTM D2425 2019. This updated standardized method was investigated for a new instrument and new sample type for a quadrupole MS to analyze a renewable aviation fuel. Lastly, the development and evaluation of a miniaturized coreflood device for analyzing candidate chemically enhanced oil recovery (cEOR) formulations of brine, surfactant(s), and polymer(s) was conducted. The miniaturized device was used in the evaluation of two different cEOR formulations to determine if the components of the recovered oil changed.