Delphine K. Farmer
Development of a rapid, sensitive and selective detector: Chemical ionization mass spectrometry with switchable electrospray reagent ions interfaced with two-dimensional gas-chromatography
Colorado State University
Chemical ionization mass spectrometry allows for sensitive detection of organic compounds along multiple axes of volatility and oxidation state. The selection of reagent ion can provide a chemical control on the types of molecules detected, allowing for bulk measurements of complex mixtures. The atmosphere is a particularly complex mixture of organic and inorganic molecules - the fate of which determines the formation and lifetime of aerosol particles and greenhouse gases, and thus radiative forcing of the planet. We use a combination of field and laboratory experiments to demonstrate that a clear understanding of reagent ion chemistry is essential for identifying molecules in ambient air, but that these measurements can provide unprecedented insight into gas-phase oxidation chemistry. We also show that the introductio of anthropogenic nitrogen- and sulfur-containing species into otherwise biogenic systems causes shifts in bulk gas-phase chemistry that follow specific trajectories along chemical coordinates. Thus we can quantify the role of specific human-induced chemical perturbations to the natural atmosphere, and speculate on their impacts to air pollution and climate.