Quantitation of 11 alkylamines in atmospheric samples: separating structural isomers by ion chromatography

Abstract

Amines are important drivers in particle formation and growth, which have implications for Earth's climate. In this work, we developed an ion chromatographic (IC) method using sample cation-exchange preconcentration for separating and quantifying the nine most abundant atmospheric alkylamines (monomethylamine (MMAH + ), dimethylamine (DMAH + ), trimethylamine (TMAH + ), monoethylamine (MEAH + ), diethylamine (DEAH + ), triethylamine (TEAH + ), monopropylamine (MPAH + ), isomonopropylamine (iMPAH + ), and monobutylamine (MBAH + )) and two alkyl diamines (1, 4-diaminobutane (DABH + ) and 1, 5-diaminopentane (DAPH + )). Further, the developed method separates the suite of amines from five common atmospheric inorganic cations (Na + , NH + 4 , K + , Mg 2+ , Ca 2+ ). All 16 cations are greater than 95 % baseline resolved and elute in a runtime of 35 min. This paper describes the first successful separation of DEAH + and TMAH + by IC and achieves separation between three sets of structural isomers, providing specificity not possible by mass spectrometry. The method detection limits for the alkylamines are in the picogram per injection range and the method precision (±1σ ) analyzed over 3 months was within 16 % for all the cations. The performance of the IC method for atmospheric application was tested with biomass-burning (BB) particle extracts collected from two forest fire plumes in Canada. In extracts of a size-resolved BB sample from an aged plume, we detected and quantified MMAH + , DMAH + , TMAH + , MEAH + , DEAH + , and TEAH + in the presence of Na + , NH + 4 , and K + at molar ratios of amine to inorganic cation ranging from 1 : 2 to 1 : 1000. Quantities of DEAH + and DMAH + of 0.2-200 and 3-1200 ng m −3 , respectively, were present in the extracts and an unprecedented amine-to-ammonium molar ratio greater than 1 was observed in particles with diameters spanning 56-180 nm. Extracts of respirable fine-mode particles (PM 2.5 ) from a summer forest fire in British Columbia in 2015 were found to contain iMPAH + , TMAH + , DEAH + and TEAH + at molar ratios of 1 : 300 with the dominant cations. The amine-to-ammonium ratio in a time series of samples never exceeded 0.15 during the sampling of the plume. These results and an amine standard addition demonstrate the robustness and sensitivity of the developed method when applied to the complex matrix of BB particle samples. The detection of multiple alkylamines in the analyzed BB samples indicates that this speciation and quantitation approach can be used to constrain BB emission estimates and the biogeochemical cycling of these reduced nitrogen species.

Characterization of organic nitrogen in aerosols at a forest site in the southern Appalachian Mountains

“…Our results provide further understanding of the patterns and composition of SOA in a remote mountain environment previously uncharacterized. Similar to our results, other studies generally find that individual groups of organic N compounds (e.g., amines, amino acids, urea) cannot explain the majority of bulk WSON (Cape et al, 2011;Day et al, 2010;Place et al, 2017;Samy et al, 2013), which globally accounts for ∼ 25 % of total N in rainfall (Cape et al, 2011;Jickells et al, 2013). As methodological advances allow for greater speciation of this large pool of atmospheric N, future work should emphasize the analysis of both primary and secondary forms of organic N in individual samples, in addition to bulk analyses, so that a more complete picture of organic N composition may be developed for specific atmospheric chemical and meteorological conditions.…”

“…There is extensive evidence showing that boreal and temperate forests are affected by anthropogenic activities, both industrial and agricultural. Such activity results in unprecedented quantities of reactive nitrogen (N) being released into the atmosphere, subsequently altering global nitrogen and carbon (C) biogeochemical cycles (Bragazza et al, 2006;Doney et al, 2007;Ollinger et al, 2002;Magnani et al, 2007;Neff et al, 2002a, b;Pregitzer et al, 2008). Nitrogen enters natural ecosystems through atmospheric deposition and biological fixation and is mainly lost through leaching and gaseous fluxes back to the atmosphere (Hungate et al, 2003).…”

“…Recent advancements have been made in the speciation of organic N in aerosol for some groups of compounds including amines, amino acids, and other nitrogenated functional groups such as organonitrates (Day et al, 2010;Place et al, 2017;Samy et al, 2013). Organic N in secondary aerosol and aerosols associated with biomass burning sources are areas of increasing interest, from both atmospheric chemistry and ecosystem exposure perspectives for which more information is needed.…”

replies to referee #2

“…The retrieval of the particle size distributions requires corrections for the charging and the transmission efficiency, which were performed according to the literature (Wiedensohler and Fissan, 1988;Karlsson and Martinsson, 2003). The mixing ratio of DMA was determined using ion chromatography with a detection limit of 0.2 to 1 pptv (5 × 10 6 to 2.5 × 10 7 cm −3 ) at a time resolution between 70 and 210 min (Praplan et al, 2012;.…”

Responce to Referee 2

“…In addition, novel in situ methods for measuring ambient air gas-phase amines have been developed, usually based on mass-spectrometric detection: chemical ionization mass spectrometry (CIMS), (Sellegri et al, 2005;You et al, 2014), ambient pressure proton transfer mass spectrometry (AmPMS) (Hanson et al, 2011;Freshour et al, 2014), chemical ionization atmospheric pressure interface time-of-flight mass spectrometry (CI-APi-TOF) Sipilä et al, 2015;Kürten et al, 2016), and TOF-CIMS (Zheng et al, 2015). These in situ techniques have short time resolution and the limits of detections are small.…”