AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Addition of an SVOC/IVOC Trap for the Thermal Desorption Aerosol Gas Chromatograph (TAG) and Its Application in Studying the Phase-Partitioning of Key Molecular Tracers in Lab-Generated Biomass Burning Organic Aerosol
CLAIRE FORTENBERRY, Michael Walker, Yaping Zhang, Dhruv Mitroo, Christopher Oxford, William Brune, Brent Williams, Washington University in St Louis
Abstract Number: 626 Working Group: Aerosol Chemistry
Abstract Semivolatile organic compounds (SVOCs) and intermediately volatile organic compounds (IVOCs) are known to compose a significant fraction of biomass burning emissions. While key molecular tracers for biomass burning organic aerosol (BBOA) have been characterized in previous studies, the gas-to-particle phase partitioning of many of the SVOCs/IVOCs is expected to change with photochemical aging and therefore merits further study.
The Thermal desorption Aerosol Gas Chromatograph (TAG) is able to achieve in situ ambient collection and molecular level speciation with hourly time resolution. While the original design of the TAG is suitable for collecting and analyzing particle-phase emissions, it has limited SVOC/IVOC analysis capability due to its inertial impaction collection and thermal desorption (CTD) system. Subsequent versions of the TAG (i.e., the SV-TAG) have utilized a metal filter cell to additionally collect the gas fraction of SVOC/IVOCs and rotates sampling with and without a denuder to separate the gas and particle fraction. Here, an alternate approach to separately collect the gas fraction parallel to the particle fraction is applied. This approach is an add-on to the original TAG system and does not replace components. In this study, the collection capability of a newly developed SVOC/IVOC trap, consisting of a custom-built diffusion denuder (for gas-phase collection) installed in parallel with denuded sampling on the original CTD cell (for particle-phase collection), was characterized using lab-generated biomass burning emissions, which were aged using a Potential Aerosol Mass (PAM) flow reactor to simulate different levels of atmospheric aging. The phase-partitioning of key molecular tracers was determined using results from the SVOC/IVOC trap and the CTD cell in the TAG. Finally, positive matrix factorization (PMF) results for both gas- and particle-phase material will be presented.