Atmos. Chem. Phys. Discuss., 11, 19443-19476, 2011
www.atmos-chem-phys-discuss.net/11/19443/2011/
doi:10.5194/acpd-11-19443-2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Formation of 3-methyl-1,2,3-butanetricarboxylic acid via gas phase oxidation of pinonic acid – a mass spectrometric study of SOA aging
L. Müller1, M. C. Reinnig1, K. H. Naumann2, H. Saathoff2, T. F. Mentel3, N. M. Donahue4, and T. Hoffmann1
1Johannes Gutenberg-Universität, Institute for inorganic Chemistry and analytical Chemistry, Duesbergweg 10–14, 55128 Mainz, Germany
2Karlsruhe Institute of Technology, Institute for Meteorology and Climate Research (IMK-AAF), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
3Forschungszentrum Jülich GmbH, ICG-2: Troposphäre, 52425 Jülich, Germany
4Carnegie Mellon University, Department of Chemical Engineering, 5000 Forbes Avenue, Pittsburgh, PA 15213-3890 USA

Abstract. This paper presents the results of mass spectrometric investigations of the OH-initiated oxidative aging of α-pinene SOA under simulated tropospheric conditions at the large aerosol chamber facility AIDA, Karlsruhe Institute of Technology. In particular, the OH-initiated oxidation of pure pinic and pinonic acid, two well-known oxidation products of α-pinene, was investigated. Two complementary analytical techniques were used, on-line atmospheric pressure chemical ionization/mass spectrometry (APCI/MS) and filter sampling followed by liquid chromatography/mass spectrometry (LC/ESI-MS). The results show that 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA), a known and very low volatile α-pinene SOA product, is formed from the oxidation of pinonic acid and that this oxidation takes place in the gas phase. This finding is confirmed by temperature-dependent aging experiments on whole SOA formed from α-pinene, in which the yield of MBTCA scales with the pinonic acid fraction in the gas phase. Based on the results, several feasible gas-phase radical mechanisms are discussed to explain the formation of MBTCA from OH-initiated pinonic acid oxidation.

Citation: Müller, L., Reinnig, M. C., Naumann, K. H., Saathoff, H., Mentel, T. F., Donahue, N. M., and Hoffmann, T.: Formation of 3-methyl-1,2,3-butanetricarboxylic acid via gas phase oxidation of pinonic acid – a mass spectrometric study of SOA aging, Atmos. Chem. Phys. Discuss., 11, 19443-19476, doi:10.5194/acpd-11-19443-2011, 2011.
 
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