HR: 11:20h
AN: A52A-05    [Abstracts]
TI: High-Resolution Mass Spectrometric Analysis of Oligomers Formed in Ozonation of Selected Monoterpenes
AU: * Desyaterik, Y
EM: yury.desyaterik@pnl.gov
AF: W.R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352, United States
AU: Walser, M L
EM: mwalser@uci.edu
AF: Department of Chemistry, University of California, Irvine, WA 92617, United States
AU: Laskin, J
EM: julia.laskin@pnl.gov
AF: Chemical Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, United States
AU: Laskin, A
EM: Alexander.Laskin@pnl.gov
AF: W.R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352, United States
AU: Nizkorodov, S
EM: nizkorod@uci.edu
AF: Department of Chemistry, University of California, Irvine, WA 92617, United States
AB: Monoterpenes constitute a significant source of the secondary organic aerosols (SOA) because of their abundant emissions from plants and high reactivity with ozone. It has been estimated that more than 50% of the total organic aerosols in specific regions are produced from monoterpene precursors. Although recent studies indicate that a significant part of secondary organic aerosols formed as a result of ozonation of monoterpenes consist of oligomeric products with high molecular weight (MW) detailed mechanism of oligomer formation is currently poorly understood. Knowledge of the molecular structure of the high MW organic products is essential for understanding of climate related properties of SOA such as hygroscopicity, CCN activity, light scattering and absorption. This work focuses on the identification of the monomeric and oligomeric chemical species present in SOA particles produced from the ozone-induced oxidation á-Pinene and d-Limonene. We take advantage of the rapidly developing tools of high-resolution mass spectrometry (HR-MS) that have the potential to analyze the aerosol particle composition without chromatographic separation techniques. High-resolution mass spectra reveal a large number of both monomeric and oligomeric products of oxidation. The combination of high resolving power (m/Δm = 60,000) and Kendrick mass defect analysis makes it possible to unambiguously determine the elemental composition for hundreds of individual compounds in SOA samples. It allows us to identify monomeric building blocks for all major oligomeric products. Positive and negative modes of HR-MS analysis provide complementary information on the composition of SOA, because less oxidized products are better observed in the positive mode while highly oxidized products tare more readily detected in the negative mode. Additional experiments using derivatization of SOA components with isotopically labeled methanol were conducted to identify compounds with aldehyde groups. An extended reaction mechanism for the formation of the monomeric and oligomeric components is proposed and will be discussed in the presentation.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting