Composition and Volatility Comparisons for Limonene Secondary Aerosol Generated from Multiple Oxidants

MANJULA CANAGARATNA, Mitchell Alton, Harald Stark, Anita Avery, Andrew Lambe, Aerodyne Research, Inc.

     Abstract Number: 130
     Working Group: Aerosol Chemistry

Abstract
Limonene is a monoterpene that is emitted from natural and anthropogenic citrus sources, with significant OVOC/SOA formation potential in indoor and outdoor environments due to its high reactivity towards gas-phase oxidants. Here, we report laboratory measurements of low-volatility gas and condensed-phase compounds obtained from the oxidation of limonene by a variety of oxidants including ozone, hydroxyl radicals, nitrate radicals, chlorine atoms, and bromine atoms. Limonene was continuously input to a novel Potential Aerosol Mass Dual Oxidation Flow Reactor configured to generate two different oxidants in separate OFRs at the same time. To maximize measurement throughput, instruments alternated sampling between the two OFRs. A fast-switching bipolar time-of-flight chemical ionization mass spectrometer (CIMS) was also utilized to detect gas and particle products. This CIMS cycled through iodide (I-), benzene (C6H6+), and acetone dimer ((C3H6O)2H+) reagent ions at a 2 second data acquisition rate per cycle, enabling the detection of a broader range of organic species than can be detected with a single reagent ion. The gas and condensed-phase oxidation products resulting from the various oxidation regimes are compared. Results from positive matrix analyses of the combined multi-reagent ion datasets are discussed and evaluated. Chemically speciated aerosol volatility measurements obtained while coupling this multi-reagent ion instrument to a FIGAERO inlet (Filter Inlet for Gases and Aerosols) are also presented.