AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Organic and Inorganic Decomposition Products from the Thermal Desorption of Atmospheric Particles
BRENT WILLIAMS, Yaping Zhang, Xiaochen Zuo, Raul Martinez, Michael Walker, Claire Fortenberry, Dhruv Mitroo, Allen H. Goldstein, Kenneth Docherty, Jose-Luis Jimenez, Washington University in St. Louis
Abstract Number: 533 Working Group: Instrumentation and Methods
Abstract Atmospheric aerosol composition is often analyzed using thermal desorption techniques to evaporate samples and deliver organic or inorganic molecules to various designs of detectors for identification and quantification. The organic fraction is composed of thousands of individual compounds, some with nitrogen- and sulfur-containing functionality, and often contains oligomeric material, much of which may be susceptible to decomposition upon heating. Here we analyze thermal decomposition products as measured by a thermal desorption aerosol gas chromatograph (TAG) capable of separating thermal decomposition products from thermally transferable molecules.
Analysis of the TAG instrument’s sample introduction (thermal decomposition) period reveals contributions of NO (m/z 30), NO2 (m/z 46), SO (m/z 48), and SO2 (m/z 64), derived from either inorganic or organic particle-phase nitrate and sulfate. CO2 (m/z 44) makes up a major component of the decomposition window, along with smaller contributions from other organic components that vary with the type of aerosol being analyzed. Ambient observations of these decomposition products compared to organic, nitrate, and sulfate mass concentrations measured by an aerosol mass spectrometer (AMS) reveal good correlations, with improved correlations for organics signal when compared to the AMS oxygenated organic aerosol component.