Condensed phase membrane introduction mass spectrometry (CP-MIMS) is a direct, in situ analysis technique that is well suited to persistent organic pollutants, pesticides, and other small molecules. In CP-MIMS, neutral analytes permeate a hollow fibre membrane, typically polydimethylsiloxane (PDMS), driven by a concentration gradient. Analytes are subsequently dissolved by a liquid (condensed) solvent acceptor phase that is continuously flowed through the membrane lumen, which finally entrains the analytes to a mass spectrometer for detection. The membrane rejects charged and particulate matrix components, therefore eliminating sample cleanup that is otherwise necessary for conventional (i.e., chromatographic) techniques. However, larger analytes may suffer from relatively lengthy response times and lower sensitivity. A heptane cosolvent was therefore doped into the PDMS membrane, resulting in a polymer inclusion membrane (PIM). Through a system coupling CP-MIMS to electrospray ionization (ESI), the use of a PIM for model compounds resulted in faster response (~3×) and improved sensitivity (~3.5×, parts per trillion level detection limits). While effective for the demonstration of the PIM, pairing ESI with CP-MIMS represents an inherent incongruity: ESI is effective for polar, hydrophilic analytes, whereas CP-MIMS (i.e., PDMS membranes) is effective for hydrophobic analytes. CP-MIMS was therefore coupled with liquid electron ionization (LEI) as a more suitable ionization strategy. In LEI, the post-membrane solvent flow is entrained at nanolitre per minute flowrates to a LEI source, where the liquid is sequentially nebulized, vaporized, and ionized. The CP-MIMS-LEI coupling was optimized for the measurements of polycyclic aromatic hydrocarbon (PAH) isomer classes from aqueous samples, demonstrating low ng/L detection limits and response times (≤1.6 min). CP-MIMS-LEI was also applied to PAH isomer classes from soil samples, demonstrating rapid sample throughput (15 samples/hr) and low μg/kg detection limits, and additionally was quantitatively comparable to conventional techniques. A similar CP-MIMS-LEI system was applied to online monitoring of catalytic oxidation and alkylation reactions, demonstrating quantitative, real-time results for harsh, complex organic reaction mixtures. A significant analytical improvement was conducted by intentionally exploiting the already present liquid acceptor phase as an in situ means of providing liquid chemical ionization (CI) reagents for improved analyte sensitivity and selectivity (i.e., CP-MIMS-LEI/CI). Acetonitrile and diethyl ether were used as a combination acceptor phase/CI reagent system (i.e., proton transfer reagents) for the direct analysis of bis(2-ethylhexyl)phthalate from house dust (6 mg/kg detection limit). CP-MIMS-LEI/CI was then applied to PAHs from soils. Using methanol and dichloromethane combination acceptor phase/CI reagents, CP-MIMS-LEI/CI was shown to quantify and resolve PAH isomers from direct soil analyses via diagnostic PAH adduct ions: [M+CH2Cl+CH3OH-HCl]+ or [M+CHCl2-HCl]+. Using these selective ions, CP-MIMS-LEI/CI was again shown to be rapid (15 soils/hr), sensitive (ng/g detection limits) and quantitatively comparable to gas chromatography-MS for PAH measurements (average percent difference of -9% across 9 PAHs in 8 soil samples). The results across this thesis present a compelling argument for direct, quantitative screening from complex samples using CP-MIMS-LEI/CI, particularly given the simple workflow and short analytical duty cycle. / Graduate

This thesis describes the on-road analysis of criteria air pollutants (CAPs) and volatile organic compounds (VOCs) from a moving vehicle. CAPs and VOCs have numerous direct and indirect effects on the environment and public health and are generated from a variety of point and diffuse sources. The concentration of these pollutants can vary on the scale of metres and seconds due to variable emission rates of sources, meteorology, and the topography of an area. CAPs are conventionally measured on a spatial scale of tens of kilometres and one hour or longer time resolution, which limits the understanding of their impact and leaving many communities lacking information regarding their air quality. VOCs are not measured as frequently as CAPs, owing to the difficulty, challenges, and cost associated with sampling. The Mobile Mass Spectrometry Lab (MMSL) was developed to collect high geospatial (15 – 1,500 m) and temporal (1 – 10 s) resolution measurements of CAPs (O3, NOx, PM2.5), CO2, CH4, and VOCs. CAPs and greenhouse gases were monitored using standard analyzers, while VOCs were measured using a proton-transfer reaction time-of-flight mass spectrometer (PTR-MS). PTR-MS is a real-time, direct, in situ technique that can monitor VOCs in the ambient atmosphere without sample collection. The PTR-MS monitored up to mass-to-charge 330 with a sample integration time of 1 or 10 seconds and had detection limits into the low- to mid-ppt. PTR-MS is a soft ionization technique that is selective to all compounds with a proton affinity less than water, which excludes the atmospheric matrix and includes most VOCs. The measurements provided by the PTR-MS provided a rich dataset for which to develop workflow and processing methods alongside sampling strategies for the collection of high geospatial and temporal VOC data. The first on-road deployment of the MMSL was performed across the Regional District of Nanaimo and the Alberni-Clayoquot Regional District in British Columbia, Canada, from July iv 2018 – April 2019 to monitor the geospatial and temporal variation in the concentration of CAPs and VOCs. VOCs detected in the areas include hydrocarbons like toluene, C2-benzenes, and terpenes, organic acids like acetic acid, oxygenated compounds like acetone and acetaldehyde, and reduced sulfur compounds like methanethiol and dimethyl sulfide. While observed concentrations of VOCs were mostly below detection limits, concentration excursions upwards of 2,200 ppb for C2-benzenes (reported as ethylbenzene) for instance, were observed across the various communities and industries that comprise central Vancouver Island. VOCs like monoterpenes, were observed near the wood industries up to 229 ppb. Combustion related VOCs, like toluene and C2-benzenes, were often observed on major transportation corridors and was found to vary significantly between seasons, with winter measurements often exceeding those made in the summer. Reduced sulfur compounds, common components of nuisance odours, were measured around a few industries like waste management and wood industries. The second on-road deployment of the MMSL focused on the analysis of VOCs in the community around a wastewater treatment plant (WWTP) to identify the source of odours in the area. VOCs were also monitored in the odour control process of the WWTP to identify the VOCs being emitted, how much were emitted, and where potential deficiencies were in the process in a unique study. Median emission rates at the facility for methanethiol, dimethyl sulfide, and dimethyl disulfide were determined to be 100, 19, and 21 kg yr-1, respectively. VOC monitoring in the community encompassed the WWTP and the other major industries in the area, including agricultural land, a composting facility, and a marina. The highest measurements of odorous reduced sulfur compounds were observed around the WWTP, upwards of 36 ppb for methanethiol. Unsupervised multivariate analysis was performed to identify groups of VOCs present and their potential sources. Three groups were identified, one of which was related to reduced sulfur compounds. This group was observed around the WWTP, indicating that the WWTP was the likely source of malodours in the community. / Graduate

Anthropogenic emissions into the troposphere can impact air quality, leading to poorer health outcomes in the affected areas. Volatile organic compounds (VOCs) are a group of chemical compounds, including some which are toxic, that are precursors in the formation of ground-level ozone and secondary organic aerosols. VOCs have a variety of sources, and the distribution of atmospheric VOCs differs significantly over time and space. Historically, the large number of chemical species present at low concentrations (parts-per-trillion to parts-per-billion by volume) have made VOCs difficult to measure in ambient air. However, with improvements in analytical instrumentation, these measurements are becoming more common place. Direct mass spectrometry (MS), such as membrane introduction mass spectrometry (MIMS) and proton-transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) facilitate real-time, continuous measurements of VOCs in air, with full scan mass spectral data capturing changes in chemical composition with high temporal resolution. Operated on-road, mobilized direct MS has been used for quantitative mapping of VOCs at the neighborhood scale, but identifying VOC sources based on the observed mixture of molecules in the full scan MS dataset has yet to be explored. This dissertation describes the use of chemometric techniques to interrogate full scan MS data, and the progression from discriminating VOC samples of known chemical composition based on full scan MIMS data through to the apportionment of VOC sources measured continuously with a PTR-ToF-MS system operating in a moving vehicle. Lab‐constructed VOC samples of known chemical composition and concentration demonstrated the use of principal component analysis (PCA) to discriminate, and k-nearest neighbours to classify, samples based on normalized full scan MIMS data. Furthermore, multivariate curve resolution-alternating least squares (MCR-ALS) was used to resolve mixtures into molecular component contributions. PCA was also used to discriminate ‘real-world’ VOC mixtures (e.g., woodsmoke VOCs, headspace above aqueous hydrocarbon samples) of unknown chemical composition measured by MIMS. Using vehicle mounted MIMS and PTR-ToF-MS systems, full scan MS data of ambient atmospheric VOCs were collected and PCA was applied to the normalized full scan MS data. A supervised analysis performed PCA on samples collected near known VOC sources, while an unsupervised analysis using PCA followed by cluster analysis was used to identify groups in a continuous, time series PTR-ToF-MS dataset measured between Nanaimo and Crofton, British Columbia (BC). In both the supervised and unsupervised analysis, samples impacted by emissions from different sources (e.g., internal combustion engines, sawmills, composting facilities, pulp mills) were discriminated. With PCA, samples were discriminated based on differences in the observed full scan MS data, however real-world samples are often impacted by multiple VOC sources. MCR-weighted ALS (MCR-WALS) was applied to the continuous, time series PTR-ToF-MS data from three field campaigns on Vancouver Island, BC for source apportionment. Variable selection based on signal-to-noise ratios was used to reduce the mass list while retaining the observed m/z that capture changes in the mixture of VOCs measured, improving model results, and reducing computation time. Both point (e.g., anthropogenic hydrocarbon emissions, pulp mill emissions) and diffuse (e.g., VOCs from forest fire smoke) VOC sources were identified in the data, and were apportioned to determine their contributions to the measured samples. The data analyzed captured fine scale changes in the ambient VOCs present in the air, and geospatial maps of each individual source, and of the source apportionment were used to visualize the distribution of VOC sources across the sampling area. This work represents the first use of MCR-WALS to identify and apportion ambient VOC sources based on continuous PTR-ToF-MS data measured from a moving vehicle. The methods described can be applied to larger scale field campaigns for the source apportionment of VOCs across multiple days to capture diurnal and seasonal variations. Identifying spatial and temporal trends in the sources of VOCs at the regional scale can help to identify pollution ‘hot spots’ and inform evidence-based public policy for improving air quality. / Graduate / 2022-08-17