You are here:
Ultrahigh-resolution FT-ICR mass spectrometry characterization of a-pinene ozonolysis SOA
Citation:
Putman, A. L., J. H. OFFENBERG, R. Fisseha, S. Kundu, T. A. Rahn, AND L. R. Mazzoleni. Ultrahigh-resolution FT-ICR mass spectrometry characterization of a-pinene ozonolysis SOA . ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 46(1):164-172, (2012).
Impact/Purpose:
The National Exposure Research Laboratory′s (NERL) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA′s mission to protect human health and the environment. HEASD′s research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EPA′s strategic plan. More specifically, our division conducts research to characterize the movement of pollutants from the source to contact with humans. Our multidisciplinary research program produces Methods, Measurements, and Models to identify relationships between and characterize processes that link source emissions, environmental concentrations, human exposures, and target-tissue dose. The impact of these tools is improved regulatory programs and policies for EPA.
Description:
Secondary organic aerosol (SOA) of α-pinene ozonolysis with and without hydroxyl radical scavenging hexane was characterized by ultrahigh-resolution. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Molecular formulas for more than 900 negative ions were identified over the mass range of 100–850 u. Hydroxyl radicals formed during the ozonolysis of α-pinene might be expected to alter the composition of SOA, however a majority of the molecular formulas were identified in all three experiments and with a few exceptions they had similar relative abundances. Thus, the detailed composition of SOA was only slightly influenced by the presence or absence of hydroxyl radical scavenging hexane. The negative-ion mass spectra of the SOA contained four groups of peaks with increasing mass spectral complexity corresponding to increasing molecular weight. The mean values of O:C decreased from 0.55 to 0.42 with increasing molecular weight, but the mean value of H:C, approximately 1.5, did not change with increasing molecular weight. The molecular formulas with the highest relative abundances in Groups I and II contained 5–7 and 7–10 oxygen atoms and 3–4 and 5–7 double bond equivalents, respectively. The molecular formulas with the highest relative abundances in Groups III and IV contained 10–13 and 13–16 oxygen atoms and 7–9 and 9–11 double bond equivalents, respectively. Observations of the oxygen content and the double bond equivalents of the SOA products suggest a complex mixture of accretion reaction mechanisms, without an easily confirmable dominating pathway.
URLs/Downloads:
Ultrahigh-resolution FT-ICR mass spectrometry characterization of a-pinene ozonolysis SOA (PDF, NA pp, 581 KB, about PDF)Atmospheric Environment
