Determination of Secondary Organic Aerosol Products from the Photooxidation of Toluene and their Implications in Ambient PM_2.5

Authors: Kleindienst T.E.¹; Conver T.S.²; McIver C.D.²; Edney E.O.³

Source: Journal of Atmospheric Chemistry, Volume 47, Number 1, January 2004 , pp. 79-100(22)

Publisher: Springer

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Abstract:

A laboratory study was carried out to investigate the secondary organic aerosol products from photooxidation of the aromatic hydrocarbon toluene. The laboratory experiments consisted of irradiating toluene/propylene/NO_x/air mixtures in a smog chamber operated in the dynamic mode and collecting submicron secondary organic aerosol samples through a sampling train that consisted of an XAD denuder and a Zefluor^TM filter. Oxidation products in the filter extracts were treated using O-(2,3,4,5,6,-pentafluorobenzyl)-hydroxylamine (PFBHA) to derivatize carbonyl groups followed by treatment with N,O-Bis(trimethylsilyl)-acetamide (BSTFA) to derivatize OH groups. The derivatized products were detected with a positive chemical ionization (CI) gas chromatography ion trap mass spectroscopy (GC-ITMS) system. The results of the GC-ITMS analyses were consistent with the previous studies that demonstrated the formation of multi-functional oxygenates. Denuder results showed that many of these same compounds were present in the gas, as well as, the particle phase. Moreover, evidence was found for a series of multifunctional acids produced as higher order oxidation products of the toluene/NO_x system. Products having nearly the same mass spectrum were also found in the ambient environment using identical analytical techniques. These products having multiple acid and alcoholic-OH moieties have substantially lower volatility than previously reported SOA products of the toluene photooxidation and might serve as an indicator for aromatic oxidation in the ambient atmosphere.

Keywords: secondary organic aerosol; polyketones; toluene oxidation products; photooxidation; chamber experiments

Document Type: Research article

DOI: http://dx.doi.org/10.1023/B:JOCH.0000012305.94498.28

Affiliations: 1: National Exposure Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, U.S.A., Email: kleindienst.tad@epa.gov 2: ManTech Environmental Technology, Inc., PO Box 12313, Research Triangle Park, NC 27709, U.S.A. 3: National Exposure Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, U.S.A.

Publication date: 2004-01-01