Photooxidation of farnesene mixtures in the presence of NOx: Analysis of reaction products and their implication to ambient PM2.5

Jaoui, Mohammed; Lewandowski, Michael; Docherty, Kenneth S.; Corse, E.W.; Lonneman, William A.; Offenberg, John H.; Kleindienst, Tadeusz E.

doi:10.1016/j.atmosenv.2015.10.091

Cited by 12 publications

(9 citation statements)

References 39 publications

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“…6). This is in contrast with typically observed daytime maxima for isoprene and monoterpenes (Alves et al, 2016;Yáñez-Serrano et al, 2015), for which reactive loss is dominated by reaction with OH and with OH / O 3 , respectively (Atkinson, 1997;Kesselmeier and Staudt, 1999), and whose daytime emissions are likely more associated with immediate release following production as a function of solar radiation input (Alves et al, 2014;Bracho-Nuñez et al, 2013;Harley et al, 2004;Jardine et al, 2015;Kuhn, 2002;Kuhn et al, 2004). To better understand the reactive loss of O 3 , the estimated cumulative loss of O 3 by reaction with sesquiterpenes compared to that by reaction with isoprene and monoterpenes is shown for the wet and dry seasons in Figs.…”

Section: Sesquiterpene Contribution To Total O 3 Reactivitycontrasting

confidence: 73%

Observations of sesquiterpenes and their oxidation products in central Amazonia during the wet and dry seasons

Yee¹,

Isaacman‐VanWertz²,

Wernis³

et al. 2018

Preprint

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Abstract. Biogenic volatile organic compounds (BVOCs) from the Amazon forest region represent the largest source of organic carbon emissions to the atmosphere globally. These BVOC emissions dominantly consist of volatile and intermediate volatility terpenoid compounds that undergo chemical transformations in the atmosphere to form oxygenated condensable gases and secondary organic aerosol (SOA). We collected quartz filter samples with 12-hour time resolution and performed hourly in-situ measurements with the Semi-Volatile Thermal desorption Aerosol Gas chromatograph (SV-TAG) at a rural site (<q>T3</q>) located to the west of the urban center of Manaus, Brazil as part of the Green Ocean Amazon (GoAmazon2014/5) field campaign to measure intermediate volatility and semi-volatile BVOCs and their oxidation products during the wet and dry seasons. We speciated and quantified 30 sesquiterpenes and four diterpenes with concentrations in the range 0.01&#8211;6.04&#8201;ng&#8201;m&#8722;3 (1&#8211;670&#8201;ppqv). We estimate that sesquiterpenes contribute approximately 14&#8201;% and 12&#8201;% to the total reactive loss of O3 via reaction with isoprene or terpenes during the wet and dry seasons, respectively. This is reduced from ~&#8201;50&#8211;70&#8201;% for within-canopy reactive O3 loss, attributed to ozonolysis of highly reactive sesquiterpenes (e.g. &#946;-caryophyllene) that are reacted away before reaching our measurement site. We further identify a suite of their oxidation products in the gas and particle phases and explore their role in biogenic SOA formation in the Central Amazon region. Synthesized authentic standards were also used to quantify gas- and particle-phase oxidation products derived from &#946;-caryophyllene. Using tracer-based scaling methods for these products, we roughly estimate that sesquiterpene oxidation contributes at least 1&#8211;18&#8201;% (median 5&#8201;%) of total submicron OA mass. However, this is likely a low-end estimate, as evidence for additional unaccounted sesquiterpenes and their oxidation products clearly exists. By comparing our field data to laboratory-based sesquiterpene oxidation experiments we confirm more than 40 additional observed compounds produced through sesquiterpene oxidation are present in Amazonian SOA, warranting further efforts towards more complete quantification.

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Section: Sesquiterpene Contribution To Total O 3 Reactivitycontrasting

confidence: 73%

Observations of sesquiterpenes and their oxidation products in central Amazonia during the wet and dry seasons

Yee¹,

Isaacman‐VanWertz²,

Wernis³

et al. 2018

Preprint

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“…Poor chromatography is often a problem when analyzing ambient polar organic compounds (POCs); therefore, derivatization procedures are an important approach for generating structural information at the molecular level. While BSTFA derivatization has been used extensively for nonnitro‐containing hydroxylated compounds, only limited studies have been associated with NACs analysis, mainly nitrophenols . Therefore, the silylation parameters including reaction temperature and time have been optimized for the NACs.…”

Section: Resultsmentioning

confidence: 99%

“…Because mass spectra of nitroaromatic and hydroxylated aromatic compounds were generated in EI mode, and mostly for the underivatized aromatic compounds, we have provided a number of mass spectra for silylated nitroaromatics and polar aromatics in EI and CI modes (Compounds 1 to 7, 17, and 37). The interpretation of silylated mass spectra for nonnitro/benzene ring containing compounds has been reported in several papers and therefore not discussed here . The information obtained from the interpretation of these mass spectra has been compared with mass spectra generated for NACs to see whether characteristic fragments were common to these classes of compounds.…”

Section: Mass Spectrometry Parameters For CI and Eimentioning

confidence: 99%

“…Although EI spectral libraries are widely used for compound identification, few EI mass spectra associated with silylated compounds are available. Based on our experience generating methane‐CI spectra of a wide variety of silylated compounds, we have found that these spectra are highly specific, reproducible, and produce characteristic fragments useful in determining structural information and molecular weight, when authentic standards are not available . In this study, 32 silylated NACs (Table ) were analyzed in EI and CI modes in the full scan (Supporting Information).…”

Section: Mass Spectrometry Parameters For CI and Eimentioning

confidence: 99%

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Characterization of aerosol nitroaromatic compounds: Validation of an experimental method

et al. 2018

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The analytical capabilities associated with the use of silylation reactions have been extended to a new class of organic molecules, nitroaromatic compounds (NACs). These compounds are a possible contributor to urban particulate matter of secondary origin which would make them important analytes due to their (1) detrimental health effects, (2) potential to affect aerosol optical properties, and (3) and usefulness for identifying PM from biomass burning. The technique is based on derivatization of the parent NACs by using N,O-bis-(trimethylsilyl)-trifluoro acetamide, one of the most prevalent derivatization reagent for analyzing hydroxylated molecules, followed by gas chromatography-mass spectrometry using electron ionization (EI) and methane chemical ionization (CI). This method is evaluated for 32 NACs including nitrophenols, methyl-/methoxy-nitrophenols, nitrobenzoic acids, and nitrobenzyl alcohols. Electron ionization spectra were characterized by a high abundance of ions corresponding to [M ] or [M - 15]. Chemical ionization spectra exhibited high abundance for [M + 1], [M - 15], and [M + 29] ions. Both EI and CI spectra exhibit ions specific to nitro group(s) for [M - 31], [M - 45], and [M - 60]. The strong abundance observed for [M ] (EI), [M - 15] (EI/CI), or [M + 1] (CI) ions is consistent with the high charge stabilizing ability associated with aromatic compounds. The combination of EI and CI ionization offers strong capabilities for detection and identification of NACs. Spectra associated with NACs, containing hydrogen, carbon, oxygen, and nitrogen atoms only, as silylated derivatives show fragment/adduct ions at either (a) odd or (b) even masses that indicate either (a) odd or (b) even number of nitro groups, respectively. Mass spectra associated with silylated NACs exhibited 3 distinct regions where characteristic fragmentation with a specific pattern associated with (1) ─OH and/or ─COOH groups, (2) ─NO group(s), and (3) benzene ring(s). These findings were confirmed with applications to chamber aerosol and ambient PM .

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“…Mass spectra of resolved peaks from these and previously analyzed filters were added to custom MS libraries and are listed in Table S1. Sesquiterpenes were oxidized in the U.S. EPA National Exposure Research Laboratory reactors (Table S2) in the dark via ozonolysis; some were also oxidized under conditions of OH oxidation in the presence of NO x according to methods described previously (Jaoui et al, 2003(Jaoui et al, , 2004(Jaoui et al, , 2013(Jaoui et al, , 2016Offenberg et al, 2017). The following sesquiterpene systems were studied: β-caryophyllene, α-cedrene, α-copaene, aromadendrene, β-farnasene, and α-humulene.…”

Section: Laboratory-generated Soa From Sesquiterpenesmentioning

confidence: 99%

Observations of sesquiterpenes and their oxidation products in central Amazonia during the wet and dry seasons

et al. 2018

View full text Add to dashboard Cite

Abstract. Biogenic volatile organic compounds (BVOCs) from the Amazon forest region represent the largest source of organic carbon emissions to the atmosphere globally. These BVOC emissions dominantly consist of volatile and intermediate-volatility terpenoid compounds that undergo chemical transformations in the atmosphere to form oxygenated condensable gases and secondary organic aerosol (SOA). We collected quartz filter samples with 12 h time resolution and performed hourly in situ measurements with a semi-volatile thermal desorption aerosol gas chromatograph (SV-TAG) at a rural site ("T3") located to the west of the urban center of Manaus, Brazil as part of the Green Ocean Amazon (GoAmazon2014/5) field campaign to measure intermediate-volatility and semi-volatile BVOCs and their oxidation products during the wet and dry seasons. We speciated and quantified 30 sesquiterpenes and 4 diterpenes with mean concentrations in the range 0.01-6.04 ng m −3 (1-670 ppq v ). We estimate that sesquiterpenes contribute approximately 14 and 12 % to the total reactive loss of O 3 via reaction with isoprene or terpenes during the wet and dry seasons, respectively. This is reduced from ∼ 50-70 % for within-canopy reactive O 3 loss attributed to the ozonolysis of highly reactive sesquiterpenes (e.g., β-caryophyllene) that are reacted away before reaching our measurement site. We further identify a suite of their oxidation products in the gas and particle phases and explore their role in biogenic SOA formation in the central Amazon region. Synthesized authentic standards were also used to quantify gas-and particle-phase oxidation products derived from β-caryophyllene. Using tracer-based scaling methods for these products, we roughly estimate that sesquiterpene oxidation contributes at least 0.4-5 % (median 1 %) of total submicron OA mass. However, this is likely a low-end estimate, as evidence for additional unaccounted sesquiterpenes and their oxidation products clearly exists. By comparing our field data to laboratory-based sesquiterpene oxidation experiments we confirm that more than 40 additional observed compounds produced through sesquiterpene oxidation are present in Amazonian SOA, warranting further efforts towards more complete quantification.

show abstract

Photooxidation of farnesene mixtures in the presence of NOx: Analysis of reaction products and their implication to ambient PM2.5

Cited by 12 publications

References 39 publications

Observations of sesquiterpenes and their oxidation products in central Amazonia during the wet and dry seasons

Observations of sesquiterpenes and their oxidation products in central Amazonia during the wet and dry seasons

Characterization of aerosol nitroaromatic compounds: Validation of an experimental method

Observations of sesquiterpenes and their oxidation products in central Amazonia during the wet and dry seasons

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