Developing analytical methods for complex mixtures
Chemically complex mixtures, such as crude oil and its derivatives, biofuels and biomaterials, are prevalent in the environment. Their sources and environmental fates are often poorly understood, owing to the complexity in their composition. Our research group focuses on developing analytical techniques to characterize these environmental mixtures. We develop techniques to speciate organic compounds in atmospheric aerosol by carbon number, branching and cyclization on a laboratory scale. Through understanding the molecular characteristics of these mixtures, we can better constrain their sources, properties, and environmental fates.
Chemical characterization of semivolatile and particle-phase emissions
Organic aerosol is a major fraction of particulate matter, and has important effects on global climate change and local air quality. It can be directly emitted from sources (primary) or formed from oxidation of volatile or semivolatile emissions (secondary). One major focus of the research group is speciating in urban emissions of semivolatile and particle-phase compounds. Specific compounds unique to various sources are used to estimate the overall contribution to atmospheric organic aerosol.
Atmospheric oxidation chemistry of organic compounds
Most organic aerosol is secondary, formed from atmospheric oxidation of gas-phase and semivolatile emissions. We simulate the oxidation of primarily emitted compounds to form secondary products in a laboratory reactor. This allows us to control important environmental variables, such as temperature, oxidants and humidity. With detailed knowledge of the composition, we can probe the effect of molecular structures on aerosol formation mechanisms. The oxidative capacity of laboratory-generated aerosol is also linked to the effect of particulate matter on human health.