Formation of Aerosol Particles from Reactions of Secondary and Tertiary Alkylamines:  Characterization by Aerosol Time-of-Flight Mass Spectrometry

Abstract

In ambient field studies conducted with aerosol time-of-flight mass spectrometry (ATOFMS), individual particle mass spectra commonly contain ion peaks at mass/charge (m/z) 86, 101, 102, and 118. Particles with mass spectra containing these peaks show a strong correlation with high relative humidity and low temperatures. In an effort to identify these peaks, a series of smog chamber studies were conducted probing the chemistry of secondary and tertiary alkylamines. Specifically, in separate studies, trimethylamine, di- and triethylamine, and di- and tripropylamine were reacted in a 1 m3 Teflon outdoor smog chamber with naturally occurring levels of gas phase oxidants in ambient air. The aerodynamic sizes and individual mass spectra of the resulting aerosol particles were acquired continuously using aerosol time-of-flight mass spectrometry (ATOFMS). Both oxidation and acid-base reactions between amines and acids commonly present in the atmosphere (i.e., nitric and sulfuric acid) appear to play roles in the formation and chemistry of organic nitrogen-containing particle phase species. Ion peaks in the individual particle mass spectra indicate the presence of alkyl ammonium salts, as well as other tentatively identified organic N-containing compounds formed by oxidation processes. Also, for the first time, tertiary alkylamine-N-oxides have been identified as alkylamine oxidation products in the aerosol particle phase. Smog chamber reactions involving triethylamine produce ATOFMS mass spectra with similar ion peak combinations as those observed in the spectra of particles commonly detected in ambient and vehicular source characterization studies. The results of this study suggest that amine chemistry involving gas-to-particle conversion and photooxidation processes may play a significant role in particle formation in regions with high amine concentrations.

Enhanced trimethylamine-containing particles during fog events detected by single particle aerosol mass spectrometry in urban Guangzhou, China

“…Mass-to-charge ratio þ59 is recognized as the dominant peak for TMA since it could not be produced from any other common amine species (Angelino et al, 2001;Rehbein et al, 2011). A total of 126,918 mass spectra for TMA-containing particles were obtained, which contributed approximately 18% on average to the total detected submicron particles by number.…”

“…Recent measurements by Silva et al (2008) showed that amines could account up to 20% of organic matter mass in fine aerosol during some wintertime periods in Utah, USA. Angelino et al (2001) reported that up to 80% of single particles contained amine signals during some episodes in Riverside, CA. To our best knowledge, amines in particulate phase were scarcely reported in China (Wang et al, 2010a).…”

Mixing state of biomass burning particles by single particle aerosol mass spectrometer in the urban area of PRD, China

“…It has been proved to be a powerful tool for analyzing the mixing state and formation mechanisms of aerosols in single particle levels (Gaston et al, 2010;Angelino et al, 2001;Moffet et al, 2004;Freney et al, 2006;Denkenberger et al, 2007;Moffet and Prather, 2009;Wang et al, 2009a;Yang et al, 2009). These accomplishments are extremely helpful to understand the impact of aerosols on the global climate.…”

A review of current applications of mass spectrometry for biomarker/molecular tracer elucidations

“…Time-of-flight mass spectrometry (TOFMS) is beginning to be applied in atmospheric chemistry to elucidate organic compounds including biomarkers, on single aerosol particles (Alvarez, Vezmar, & Whetten, 1998;Noble & Prather, 2000;Angelino, Suess, & Prather, 2001;Whiteaker & Prather, 2003). The organic matter of individual aerosol particles is vaporized by laser and ionized in the TOFMS.…”