The ozonolysis of primary aliphatic amines in fine particles J. Zahardis, S. Geddes, and G. A. Petrucci Department of Chemistry, University of Vermont, Burlington, VT 05405, USA
Abstract. The oxidative processing by ozone of the particulate amines octadecylamine
(ODA) and hexadecylamine (HDA) is reported. Ozonolysis of these amines
resulted in strong NO2– and NO3– ion signals that
increased with ozone exposure as monitored by photoelectron resonance
capture ionization aerosol mass spectrometry. These products suggest a
mechanism of progressive oxidation of the particulate amines to
nitroalkanes. Additionally, a strong ion signal at 125 m/z is assigned to
the ion NO3– (HNO3). For ozonized mixed particles containing
ODA or HDA + oleic acid (OL), with pO3≥3×10–7 atm, imine,
secondary amide, and tertiary amide products were measured. These products
most likely arise from reactions of amines with aldehydes (for imines) and
stabilized Criegee intermediates (SCI) or secondary ozonides (for amides)
from the fatty acid. The routes to amides via SCI and/or secondary ozonides
were shown to be more important than comparable amide forming reactions
between amines and organic acids, using azelaic acid as a test compound.
Finally, direct evidence is provided for the formation of a surface barrier
in the ODA + OL reaction system that resulted in the retention of OL at high
ozone exposures (up to 10−3 atm for 17 s). This effect was not observed
in HDA + OL or single component OL particles, suggesting that it may be a
species-specific surfactant effect from an in situ generated amide or imine.
Implications to tropospheric chemistry, including particle bound amines as
sources of oxidized gas phase nitrogen species (e.g.~NO2, NO3),
formation of nitrogen enriched HULIS via ozonolysis of amines and source
apportionment are discussed.
Citation: Zahardis, J., Geddes, S., and Petrucci, G. A.: The ozonolysis of primary aliphatic amines in fine particles, Atmos. Chem. Phys., 8, 1181-1194, doi:10.5194/acp-8-1181-2008, 2008.