HR: 1340h
AN: A33B-0877 [Abstracts]
TI: A Thermal Desorption Chemical Ionization Mass Spectrometer for the In Situ Measurement of Aerosol
Organic Compounds
AU: * Thornberry, T
EM: troy.thornberry@noaa.gov
AF: NOAA Aeronomy Laboratory, 325 Broadway, Boulder, CO 80305
United States
AU: * Thornberry, T
EM: troy.thornberry@noaa.gov
AF: CIRES, University of Colorado, Boulder, CO 80309
United States
AU: Murphy, D M
EM: Daniel.M.Murphy@noaa.gov
AF: NOAA Aeronomy Laboratory, 325 Broadway, Boulder, CO 80305
United States
AU: Lovejoy, E R
EM: Edward.R.Lovejoy@noaa.gov
AF: NOAA Aeronomy Laboratory, 325 Broadway, Boulder, CO 80305
United States
AB:
Organic material has been observed to comprise a significant fraction of organic aerosol mass in many regions of the
troposphere. The organic compounds that comprise the organic fraction of atmospheric aerosol have the potential to affect
the radiative and microphysical properties of the aerosol, with concomitant impacts on the role of the aerosol in climate
forcing through direct and indirect effects. Knowledge of the organic compounds in atmospheric aerosols and their spatial
distribution is needed to determine their effect on aerosol properties as well as to elucidate the role of aerosols in the
chemistry of the atmosphere. The speciated measurement of aerosol organic compounds poses a significant experimental
challenge due to the complexity and large number of organic species, and the low concentration at which individual species
are present.
A prototype instrument has been designed and built to make in situ speciated measurements of aerosol organic compounds. The
instrument is composed of an aerosol collection/thermal desorption inlet coupled to a custom chemical ionization ion trap
mass spectrometer. Aerosols are collected over a variable time by impaction on a target stage. The stage is then rapidly
heated to volatilize the organic compounds into a small flow of helium carrier gas and conveyed to an ion-molecule reaction
drift tube where proton transfer from H3O+ is used to softly ionize organic species. The ionized analyte molecules
are then trapped and mass analyzed using a quadrupole ion trap. Results from preliminary experiments using
laboratory-generated aerosol will be discussed
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0365 Troposphere: composition and chemistry
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005