Abstract
Abstract. An ion chromatographic method is described for the quantification of the simple alkyl amines: methylamine (MA), dimethylamine (DMA), trimethylamine (TMA), ethylamine (EA), diethylamine (DEA) and triethylamine (TEA), in the ambient atmosphere. Limits of detection (3σ) are in the tens of pmol range for all of these amines, and good resolution is achieved for all compounds except for TMA and DEA. The technique was applied to the analysis of time-integrated samples collected using a micro-orifice uniform deposition impactor (MOUDI) with ten stages for size resolution of particles with aerodynamic diameters between 56 nm and 18 μm. In eight samples from urban and rural continental airmasses, the mass loading of amines consistently maximized on the stage corresponding to particles with aerodynamic diameters between 320 and 560 nm. The molar ratio of amines to ammonium (R3NH+/NH4+) in fine aerosol ranged between 0.005 and 0.2, and maximized for the smallest particle sizes. The size-dependence of the R3NH+/NH4+ ratio indicates differences in the relative importance of the processes leading to the incorporation of amines and ammonia into secondary particles. The technique was also used to make simultaneous hourly online measurements of amines in the gas phase and in fine particulate matter using an Ambient Ion Monitor Ion Chromatograph (AIM-IC). During a ten day campaign in downtown Toronto, DMA, TMA + DEA, and TEA were observed to range from below detection limit to 2.7 ppt in the gas phase. In the particle phase, MAH+ and TMAH+ + DEAH+ were observed to range from below detection limit up to 15 ng m−3. The presence of detectable levels of amines in the particle phase corresponded to periods with higher relative humidity and higher mass loadings of nitrate. While the hourly measurements made using the AIM-IC provide data that can be used to evaluate the application of gas-particle partitioning models to amines, the strong size-dependence of the R3NH+/NH4+ ratio indicates that using bulk measurements may not be appropriate.
Highlights
Recent ambient measurements of amines in the gas and particle phase have prompted research into their role in the formation and growth of atmospheric particulate matter
The sum of the particulate alkyl amines was never more than 1% of the PM2.5 aerosol mass loadings
The final column includes the molar ratio of the sum of amines to ammonium (R3NH+/NH+4 ) in PM1.8, the variability of which depends more on the mass loading of NH+4 than that of R3NH+
Summary
Recent ambient measurements of amines in the gas and particle phase have prompted research into their role in the formation and growth of atmospheric particulate matter. Amine emissions have been detected from animal husbandry operations (Mosier et al, 1973; Schade and Crutzen, 1995), decomposition of organic matter on land and in the oceans (Van Neste et al, 1987; Gibb et al, 1999; Miyazaki et al, 2010; Sorooshian et al, 2009), and from biomass burning and the incineration of waste (Finlayson-Pitts and Pitts, 2000; Chang et al, 2003). The amines emitted in the greatest quantity to the atmosphere are thought to be the simple alkyl amines: methylamine (MA), dimethylamine (DMA), trimethylamine (TMA), ethylamine (EA), diethylamine (DEA) and triethylamine (TEA). Amines are often present concomitantly with NH3, typically at mixing ratios 1–3 orders of magnitude smaller
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
