| Polar organic compounds (POC) are ubiquitous constituents of tropospheric aerosol arising from both primary emission sources and secondary atmospheric transformation processes. POC are not well characterized due to the analytical difficulty encountered in using traditional gas chromatography/mass spectrometry (GC/MS) techniques. Chemically altered or derivatized polar functional groups can greatly improve chromatographic behavior and/or detectability, thus, permitting analysis of compounds not directly amenable to GC/MS analysis due to inadequate volatility or stability. This dissertation describes the development of a comprehensive analytical GC/MS method to identify and quantify POC using a trimethylsilylation derivatization for analysis of compounds with hydroxyl and carboxyl functional groups. Quantification of POC originating from primary emission sources of fine particulate matter (PM2.5) including biomass combustion, meat cooking, on- and off-road vehicles, and vehicle abrasions and ambient samples are presented.; Aliphatic and aromatic organic acids, methoxylated phenols, and anhydrosugars were analyzed in one GC/MS method after trimethylsilylation in the atmospheric complex mixture. Comparison of methylation and trimethylsilylation of organic acids showed very good agreement with enhanced detectability after trimethylsilylation of POC. The POC fraction of total carbon was very high in emissions of biomass combustion from wildland fuels, residential woods, agricultural straws, and prescribed burns. Several unique POC are emitted in biomass combustion, however the abundances of these compounds were highly variable. The variability was not consistent with other variable combustion emissions, such as total organic carbon, PM2.5 mass, or carbon monoxide. These variations in replicated emission source tests have significant consequences for receptor air quality models. Analyses of annual average PM2.5 samples from the San Joaquin Valley in Central California showed a high abundance of POC. The POC fraction of total carbon ranged from 4% to 10% of the annual average. Molecular markers of biomass combustion constituted the largest fraction of POC followed by alkanoic and alkanedioic acids. |
