HR: 1340h
AN: A53A-0170    [Abstracts]
TI: A Minimal Fragmentation Approach to Real Time Aerosol Mass Spectrometry: A New Tool for Detailed Laboratory Studies of Organic Aerosol Aging
AU: * Campuzano-Jost, P
EM: pcampuzano@chem.ubc.ca
AF: University of British Columbia, Chemistry Department, 2036 Main Mall, Vancouver, BC V6T 1Z1 Canada
AU: Hanna, S
EM: shanna@chem.ubc.ca
AF: University of British Columbia, Chemistry Department, 2036 Main Mall, Vancouver, BC V6T 1Z1 Canada
AU: Simpson, E
EM: esimpson@chem.ubc.ca
AF: University of British Columbia, Chemistry Department, 2036 Main Mall, Vancouver, BC V6T 1Z1 Canada
AU: Robb, D
EM: drobb@chem.ubc.ca
AF: University of British Columbia, Chemistry Department, 2036 Main Mall, Vancouver, BC V6T 1Z1 Canada
AU: Blades, M W
EM: blades@chem.ubc.ca
AF: University of British Columbia, Chemistry Department, 2036 Main Mall, Vancouver, BC V6T 1Z1 Canada
AU: Hepburn, J W
EM: hepburn@chem.ubc.ca
AF: University of British Columbia, Chemistry Department, 2036 Main Mall, Vancouver, BC V6T 1Z1 Canada
AU: Bertram, A K
EM: bertram@chem.ubc.ca
AF: University of British Columbia, Chemistry Department, 2036 Main Mall, Vancouver, BC V6T 1Z1 Canada
AB: The study of the atmospheric distribution and chemical processing of both biogenic and anthropogenic organics is one of the oldest and still most enduring challenges in atmospheric chemistry. The large number and structural complexity of many of the compounds as well as the high reactivity of many intermediates makes it hard to design analytical tools that are at the same time sensitive enough as well as being reasonably broad in scope. Despite big advances in techniques to characterize the gaseous phase component, there is still a dearth of instruments capable of doing the same for the organic aerosol component. This is due in part to the type of the compounds present in the aerosol phase, which in general lend themselves less to classical analytical methods such as GC/MS, as well as the inherent problems of any aerosol analysis, namely to transfer the aerosol to a suitable phase for analysis without altering it and while keeping track, at the same time, of the physical properties of the aerosol. Although impaction methods coupled to conventional analysis techniques have some specific advantages, the most widely used approach is the aerosol mass spectrometer. Unlike their predecessors, current aerosol mass spectrometer designs do a reasonably good job of delivering a representative sample of the aerosol phase to the detector while keeping track of the physical properties of the aerosol. However, the ionization step (either multitphoton absorption or electron impact in most cases) still leads to massive fragmentation of all but the most stable organics, making it very difficult to characterize individual compounds beyond establishing their functional groups(Allan et al. 2003; Su et al. 2004). Single photon near threshold ionization has been proposed and used recently (Oktem et al. 2004; Nash et al. 2005), but the challenges of producing coherent VUV radiation has led to a high detection threshold and a still significant amount of fragmentation, since these studies have used almost exclusively a single photon energy (10.5 eV) to ionize all molecules. We have constructed a new real time aerosol mass spectrometer, based on the designs of Su et al. (2004) & Sykes et al. (2002), which incorporates a new, high-powered, fully tunable VUV source (115-190 nm, 6.5-11 eV ionization energy). This enables us to ionize quantitatively with little to no fragmentation almost all atmospherically relevant organic compounds. Coupled with an ion trap where the primary ions can be stored for further structural analysis, this instrument promises to be both universal and sensitive enough to allow for detailed studies of SOA formation as well as the aging of mixed aerosols. References: Allan, J.D., J.L. Jimenez, et al. (2003)."Quantitative sampling using an Aerodyne aerosol mass spectrometer: 1.Techniques of data interpretation and error analysis" J.Geophys.Res. 108(D9) Nash, D.G., X.F. Liu, et al. (2005)."Aerosol particle mass spectrometry with low photon energy laser ionization" Inter.J.Mass Spec. 241(2-3):89 Oktem,B., M.P. Tolocka, et al. (2004)."On-line analysis of organic components in fine and ultrafine particles by photoionization aerosol mass spectrometry" Anal.Chem. 76(2):253 Su, Y.X., M.F. Sipin, et al. (2004)."Development and characterization of an aerosol time-of-flight mass spectrometer with increased detection efficiency" Anal.Chem. 76(3):712 Sykes, D.C., E. Woods, et al. (2002)."Thermal vaporization-vacuum ultraviolet laser ionization time-of-flight mass spectrometry of single aerosol particles" Anal.Chem. 74(9):2048
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0320 Cloud physics and chemistry
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005