title: Identification of organic nitrates in the NO3 radical initiated oxidation of alpha-pinene by atmospheric pressure chemical ionization mass spectrometry.
abstract: The gas-phase reactions of nitrate radicals (NO3) with biogenic organic compounds are a major sink for these organics during night-time. These reactions form secondary organic aerosols, including organic nitrates that can undergo long-range transport, releasing NOx downwind. We report here studies of the reaction of NO3 with alpha-pinene at 1 atm in dry synthetic air (relative humidity approximately 3%) and at 298 K using atmospheric pressure chemical ionization triple quadrupole mass spectrometry (APCI-MS) to identify gaseous and particulate products. The emphasis is on the identification of individual organic nitrates in the particle phase that were obtained by passing the product mixture through a denuder to remove gas-phase reactants and products prior to entering the source region of the mass spectrometer. Filter extracts were also analyzed by GC-MS and by APCI time-of-flight mass spectrometry (APCI-ToF-MS) with methanol as the proton source. In addition to pinonaldehyde and pinonic acid, five organic nitrates were identified in the particles as well as in the gas phase: 3-oxopinane-2-nitrate, 2-hydroxypinane-3-nitrate, pinonaldehyde-PAN, norpinonaldehyde-PAN, and (3-acetyl-2,2-dimethyl-3-nitrooxycyclobutyl)acetaldehyde. Furthermore, there was an additional first-generation organic nitrate product tentatively identified as a carbonyl hydroxynitrate with a molecular mass of 229. These studies suggest that a variety of organic nitrates would partition between the gas phase and particles in the atmosphere, and serve as a reservoir for NOx.
authors.affiliation: Department of Chemistry, University of California Irvine, California 92697-2025, USA.
authors.forename: Véronique
authors.initials: V
authors.lastname: Perraud
authors.forename: Emily A
authors.initials: EA
authors.lastname: Bruns
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Ezell
authors.forename: Stanley N
authors.initials: SN
authors.lastname: Johnson
authors.forename: John
authors.initials: J
authors.lastname: Greaves
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Finlayson-Pitts
mesh_terms: D000393:Air Pollutants / Q000032:analysis / Q000737:chemistry*; D001272:Atmosphere / Q000737:chemistry*; D001274:Atmospheric Pressure; D000081008:Bicyclic Monoterpenes; D013058:Mass Spectrometry; D039821:Monoterpenes / Q000737:chemistry*; D009566:Nitrates / Q000032:analysis* / Q000737:chemistry
chemical_list: D000393:Air Pollutants; D000081008:Bicyclic Monoterpenes; D039821:Monoterpenes; D009566:Nitrates; C005451:alpha-pinene