Classification of Novel Chemical Markers in Secondary Organic Aerosol Formation through Incorporation of Laboratory and Ambient “Unknown” Species into an Open-Access Mass Spectral Database (UCB-GLOBES)

LINDSAY YEE, Emily Franklin, Robert Weber, Taekyu Joo, Masayuki Takeuchi, Gamze Eris, Weiqi Xu, Nga Lee Ng, Yuzhi Chen, John Shilling, Allen Goldstein, University of California, Berkeley

     Abstract Number: 206
     Working Group: Aerosol Chemistry

Abstract
Ambient organic aerosols contain hundreds to thousands of unique compounds, yet positive chemical identification is typically limited since most atmospheric compounds are uniquely created in the atmosphere and few authentic standards exist. This results in analyses focused on tracking a fewer number of well-known chemical markers for specific pathways to secondary organic aerosol (SOA) formation. To better understand the atmospheric importance of “unknowns,” we have analyzed laboratory and field samples of organic aerosols on quartz filters representing a variety of sample types and chemical regimes (e.g. biomass burning, isoprene and terpene oxidation, natural, rural, and urban environments) using two-dimensional gas chromatography with high-resolution time-of-flight mass spectrometry. In total, we have extended the open-access electron impact mass spectral database known as the University of California, Berkeley, Goldstein Library of Organic Biogenic and Environmental Spectra (UCB-GLOBES) to include ~25,000 mass spectra. By contrasting the chemical composition of species observed in laboratory oxidation experiments with known precursors and those observed in field samples (e.g. Southeast U.S. and Central Amazon), we investigate which unknown species can serve as new chemical markers for specific SOA pathways and further classify these markers by predicted chemical properties (e.g. average carbon oxidation state, carbon number, vapor pressure).