scholarly journals Real-time detection of highly oxidized organosulfates and BSOA marker compounds during the F–BEACh 2014 field study

2016 ◽  
Author(s):  
Martin Brüggemann ◽  
Laurent Poulain ◽  
Andreas Held ◽  
Torsten Stelzer ◽  
Christoph Zuth ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Field Study ◽  
Gas Phase ◽  
Organic Compounds ◽  
Atmospheric Pressure ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Aerosol Mass ◽  
Marker Compounds ◽  
Sulfur Containing

Abstract. The chemical composition of organic aerosols was analyzed using complementary mass spectrometric techniques during a field study in Central Europe in July 2014 (Fichtelgebirge – Biogenic Emission and Aerosol Chemistry, F–BEACh 2014). Aerosols were analyzed in real-time by Aerosol Flowing Atmospheric-Pressure Afterglow Mass Spectrometry (AeroFAPA–MS), Aerosol Mass Spectrometry (AMS), and Chemical Ionization Atmospheric-Pressure interface Time-of-Flight Mass Spectrometry (CI–APiToF–MS). In addition, offline detection of acidic organic compounds was conducted by non-target screening of filter samples using High Resolution Mass Spectrometry (HRMS) in combination with Ultra-High Pressure Liquid Chromatography (UHPLC). In total, 93 acidic organic compounds were identified as characteristic contributors to the organic aerosol mass at the site. Among the carbon-, hydrogen-, oxygen-containing compounds, several common biogenic secondary organic aerosol (BSOA) marker compounds were detected. High concentrations were found for the monoterpene photooxidation products 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA) and 3 carboxyheptanedioic acid, suggesting that α-/β-pinene and d-limonene oxidation products were dominating the organic aerosol fraction. In agreement, volatile organic compound (VOC) measurements showed high mixing ratios for these monoterpenes. Moreover, the high abundance of MBTCA and 3-carboxyheptanedioic acid and their concentration ratios to earlier-generation oxidation products, such as pinic acid, indicate that aged aerosol masses were present during the campaign period. HYSPLIT trajectory calculations revealed that most of the arriving air masses traveled long distances (>1,500 km) over land with high solar radiation, further supporting this hypothesis. Around 47 % of the detected compounds from the filter sample analysis were sulfur-containing, suggesting a high anthropogenic impact on biogenic emissions and their oxidation processes. Among the sulfur-containing compounds, several organosulfates, nitrooxy organosulfates, and highly oxidized organosulfates (HOOS) were unambiguously identified. In addition, correlations among HOOS classes, sulfate and highly oxidized multifunctional organic compounds (HOMs) were investigated. The results support the hypothesis of previous studies that HOOS are formed by reactions of gas-phase HOMs with particulate sulfate. Furthermore, a good agreement was observed between HOOS formation and gas-phase peroxyradical (RO2•) concentrations, measured by the CI–APiTOF–MS. This finding suggests RO2• to be either a direct or indirect precursor for HOOS. In addition, periods with high relative humidity revealed that aqueous-phase chemistry might play a major role in HOOS production.

scholarly journals Real-time detection of highly oxidized organosulfates and BSOA marker compounds during the F-BEACh 2014 field study

2017 ◽  
Vol 17 (2) ◽  
pp. 1453-1469 ◽  
Author(s):  
Martin Brüggemann ◽  
Laurent Poulain ◽  
Andreas Held ◽  
Torsten Stelzer ◽  
Christoph Zuth ◽  
...  
Keyword(s):  
Field Study ◽  
Gas Phase ◽  
High Resolution Mass Spectrometry ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Mixing Ratios ◽  
Aerosol Mass ◽  
High Solar Radiation ◽  
Marker Compounds ◽  
High Concentrations

Abstract. The chemical composition of ambient organic aerosols was analyzed using complementary mass spectrometric techniques during a field study in central Europe in July 2014 (Fichtelgebirge – Biogenic Emission and Aerosol Chemistry, F-BEACh 2014). Among several common biogenic secondary organic aerosol (BSOA) marker compounds, 93 acidic oxygenated hydrocarbons were detected with elevated abundances and were thus attributed to be characteristic for the organic aerosol mass at the site. Monoterpene measurements exhibited median mixing ratios of 1.6 and 0.8 ppbV for in and above canopy levels respectively. Nonetheless, concentrations for early-generation oxidation products were rather low, e.g., pinic acid (c  =  4.7 (±2.5) ng m−3). In contrast, high concentrations were found for later-generation photooxidation products such as 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA, c  =  13.8 (±9.0) ng m−3) and 3-carboxyheptanedioic acid (c  =  10.2 (±6.6) ng m−3), suggesting that aged aerosol masses were present during the campaign period. In agreement, HYSPLIT trajectory calculations indicate that most of the arriving air masses traveled long distances (>  1500 km) over land with high solar radiation. In addition, around 47 % of the detected compounds from filter sample analysis contained sulfur, confirming a rather high anthropogenic impact on biogenic emissions and their oxidation processes. Among the sulfur-containing compounds, several organosulfates, nitrooxy organosulfates, and highly oxidized organosulfates (HOOS) were tentatively identified by high-resolution mass spectrometry. Correlations among HOOS, sulfate, and highly oxidized multifunctional organic compounds (HOMs) support the hypothesis of previous studies that HOOS are formed by reactions of gas-phase HOMs with particulate sulfate. Moreover, periods with high relative humidity indicate that aqueous-phase chemistry might play a major role in HOOS production. However, for dryer periods, coinciding signals for HOOS and gas-phase peroxyradicals (RO2•) were observed, suggesting RO2• to be involved in HOOS formation.

scholarly journals Characterization of secondary organic aerosol from heated-cooking-oil emissions: evolution in composition and volatility

2021 ◽  
Vol 21 (6) ◽  
pp. 5137-5149 ◽  
Author(s):  
Manpreet Takhar ◽  
Yunchun Li ◽  
Arthur W. H. Chan
Keyword(s):  
Gas Phase ◽  
Organic Compounds ◽  
Secondary Organic Aerosol ◽  
Carbon Number ◽  
Complex Mixture ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Atmospheric Evolution ◽  
Oxidative Aging ◽  
Cooking Oil

Abstract. Cooking emissions account for a major fraction of urban organic aerosol. It is therefore important to understand the atmospheric evolution in the physical and chemical properties of organic compounds emitted from cooking activities. In this work, we investigate the formation of secondary organic aerosol (SOA) from oxidation of gas-phase organic compounds from heated cooking oil. The chemical composition of cooking SOA is analyzed using thermal desorption–gas chromatography–mass spectrometry (TD–GC–MS). While the particle-phase composition of SOA is a highly complex mixture, we adopt a new method to achieve molecular speciation of the SOA. All the GC-elutable material is classified by the constituent functional groups, allowing us to provide a molecular description of its chemical evolution upon oxidative aging. Our results demonstrate an increase in average oxidation state (from −0.6 to −0.24) and decrease in average carbon number (from 5.2 to 4.9) with increasing photochemical aging of cooking oil, suggesting that fragmentation reactions are key processes in the oxidative aging of cooking emissions within 2 d equivalent of ambient oxidant exposure. Moreover, we estimate that aldehyde precursors from cooking emissions account for a majority of the SOA formation and oxidation products. Overall, our results provide insights into the atmospheric evolution of cooking SOA, a majority of which is derived from gas-phase oxidation of aldehydes.

scholarly journals Formation of Highly Oxygenated Low-Volatility Products from Cresol Oxidation

2016 ◽  
Author(s):  
Rebecca H. Schwantes ◽  
Katherine A. Schilling ◽  
Renee C. McVay ◽  
Hanna Lignell ◽  
Matthew M. Coggon ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Ring Opening ◽  
Chemical Ionization ◽  
First Generation ◽  
Direct Analysis ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Ionization Mass ◽  
Particle Phase

Abstract. Hydroxyl radical (OH) oxidation of toluene produces the ring-retaining products cresol and benzaldehyde, and the ring-opening products bicyclic intermediate compounds and epoxides. Here, first- and later-generation OH oxidation products from cresol and benzaldehyde are identified in laboratory chamber experiments. For benzaldehyde, first-generation ring-retaining products are identified, but later-generation products are not detected. For cresol, low-volatility (saturation mass concentration, C* ~ 3.5 × 104–7.7 × 10−3 μg m−3) first- and later-generation ring-retaining products are identified. Subsequent OH addition to the aromatic ring of o-cresol leads to compounds such as hydroxy, dihydroxy, and trihydroxy methyl benzoquinones and dihydroxy, trihydroxy, tetrahydroxy, and pentahydroxy toluenes. These products are detected in the gas phase by chemical ionization mass spectrometry (CIMS) and in the particle phase using offline direct analysis in real time mass spectrometry (DART-MS). Our data suggest that the yield of trihydroxy toluene from dihydroxy toluene is substantial. While an exact yield cannot be reported as authentic standards are unavailable, we find that a yield for trihydroxy toluene from dihydroxy toluene of ~ 0.7 (equal to the yield of dihydroxy toluene from o-cresol) is consistent with experimental results for o-cresol oxidation under low-NO conditions. These results suggest that even though the cresol pathway accounts for only ~ 20 % of the oxidation products of toluene, it is the source of a significant fraction (~ 20–40 %) of toluene secondary organic aerosol (SOA) due to the formation of low-volatility products.

scholarly journals Investigating the use of secondary organic aerosol as seed particles in simulation chamber experiments

2011 ◽  
Vol 11 (12) ◽  
pp. 5917-5929 ◽  
Author(s):  
J. F. Hamilton ◽  
M. Rami Alfarra ◽  
K. P. Wyche ◽  
M. W. Ward ◽  
A. C. Lewis ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Ion Cyclotron Resonance ◽  
Photo Oxidation ◽  
Seed Particles ◽  
Aerosol Mass ◽  
Seed Aerosol ◽  
Limonene Oxidation

Abstract. The use of β-caryophyllene secondary organic aerosol particles as seeds for smog chamber simulations has been investigated. A series of experiments were carried out in the Manchester photochemical chamber as part of the Aerosol Coupling in the Earth System (ACES) project to study the effect of seed particles on the formation of secondary organic aerosol (SOA) from limonene photo-oxidation. Rather than use a conventional seed aerosol containing ammonium sulfate or diesel particles, a method was developed to use in-situ chamber generated seed particles from β-caryophyllene photo-oxidation, which were then diluted to a desired mass loading (in this case 4–13 μg m−3). Limonene was then introduced into the chamber and oxidised, with the formation of SOA seen as a growth in the size of oxidised organic seed particles from 150 to 325 nm mean diameter. The effect of the partitioning of limonene oxidation products onto the seed aerosol was assessed using aerosol mass spectrometry during the experiment and the percentage of m/z 44, an indicator of degree of oxidation, increased from around 5 to 8 %. The hygroscopicity of the aerosol also changed, with the growth factor for 200 nm particles increasing from less than 1.05 to 1.25 at 90 % RH. The detailed chemical composition of the limonene SOA could be extracted from the complex β-caryophyllene matrix using two-dimensional gas chromatography (GC × GC) and liquid chromatography coupled to mass spectrometry. High resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICR-MS) was used to determine exact molecular formulae of the seed and the limonene modified aerosol. The average O:C ratio was seen to increase from 0.32 to 0.37 after limonene oxidation products had condensed onto the organic seed.

scholarly journals Secondary organic aerosol production from pinanediol, a semi-volatile surrogate for first-generation oxidation products of monoterpenes

2018 ◽  
Vol 18 (9) ◽  
pp. 6171-6186 ◽  
Author(s):  
Penglin Ye ◽  
Yunliang Zhao ◽  
Wayne K. Chuang ◽  
Allen L. Robinson ◽  
Neil M. Donahue
Keyword(s):  
Organic Compounds ◽  
First Generation ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Particle Formation ◽  
Oxidation Products ◽  
Basis Set ◽  
New Particle Formation ◽  
Aerosol Mass ◽  
Volatile Precursor

Abstract. We have investigated the production of secondary organic aerosol (SOA) from pinanediol (PD), a precursor chosen as a semi-volatile surrogate for first-generation oxidation products of monoterpenes. Observations at the CLOUD facility at CERN have shown that oxidation of organic compounds such as PD can be an important contributor to new-particle formation. Here we focus on SOA mass yields and chemical composition from PD photo-oxidation in the CMU smog chamber. To determine the SOA mass yields from this semi-volatile precursor, we had to address partitioning of both the PD and its oxidation products to the chamber walls. After correcting for these losses, we found OA loading dependent SOA mass yields from PD oxidation that ranged between 0.1 and 0.9 for SOA concentrations between 0.02 and 20 µg m−3, these mass yields are 2–3 times larger than typical of much more volatile monoterpenes. The average carbon oxidation state measured with an aerosol mass spectrometer was around −0.7. We modeled the chamber data using a dynamical two-dimensional volatility basis set and found that a significant fraction of the SOA comprises low-volatility organic compounds that could drive new-particle formation and growth, which is consistent with the CLOUD observations.

scholarly journals Campholenic aldehyde ozonolysis: a mechanism leading to specific biogenic secondary organic aerosol constituents

2014 ◽  
Vol 14 (2) ◽  
pp. 719-736 ◽  
Author(s):  
A. Kahnt ◽  
Y. Iinuma ◽  
A. Mutzel ◽  
O. Böge ◽  
M. Claeys ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Negative Ion ◽  
Mass Spectrometry Analysis ◽  
Radical Scavenger ◽  
Ambient Aerosol ◽  
Campholenic Aldehyde

Abstract. In the present study, campholenic aldehyde ozonolysis was performed to investigate pathways leading to specific biogenic secondary organic aerosol (SOA) marker compounds. Campholenic aldehyde, a known α-pinene oxidation product, is suggested to be a key intermediate in the formation of terpenylic acid upon α-pinene ozonolysis. It was reacted with ozone in the presence and absence of an OH radical scavenger, leading to SOA formation with a yield of 0.75 and 0.8, respectively. The resulting oxidation products in the gas and particle phases were investigated employing a denuder/filter sampling combination. Gas-phase oxidation products bearing a carbonyl group, which were collected by the denuder, were derivatised by 2,4-dinitrophenylhydrazine (DNPH) followed by liquid chromatography/negative ion electrospray ionisation time-of-flight mass spectrometry analysis and were compared to the gas-phase compounds detected by online proton-transfer-reaction mass spectrometry. Particle-phase products were also analysed, directly or after DNPH derivatisation, to derive information about specific compounds leading to SOA formation. Among the detected compounds, the aldehydic precursor of terpenylic acid was identified and its presence was confirmed in ambient aerosol samples from the DNPH derivatisation, accurate mass data, and additional mass spectrometry (MS2 and MS3 fragmentation studies). Furthermore, the present investigation sheds light on a reaction pathway leading to the formation of terpenylic acid, involving α-pinene, α-pinene oxide, campholenic aldehyde, and terpenylic aldehyde. Additionally, the formation of diaterpenylic acid acetate could be connected to campholenic aldehyde oxidation. The present study also provides insights into the source of other highly functionalised oxidation products (e.g. m / z 201, C9H14O5 and m / z 215, C10H16O5), which have been observed in ambient aerosol samples and smog chamber-generated monoterpene SOA. The m / z 201 and 215 compounds were tentatively identified as a C9- and C10-carbonyl-dicarboxylic acid, respectively, based on reaction mechanisms of campholenic aldehyde and ozone, as well as detailed interpretation of mass spectral data, in conjunction with the formation of corresponding DNPH derivatives.

scholarly journals Phase partitioning and volatility of secondary organic aerosol components formed from α-pinene ozonolysis and OH oxidation: the importance of accretion products and other low volatility compounds

2015 ◽  
Vol 15 (14) ◽  
pp. 7765-7776 ◽  
Author(s):  
F. D. Lopez-Hilfiker ◽  
C. Mohr ◽  
M. Ehn ◽  
F. Rubach ◽  
E. Kleist ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Mass Spectrometer ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Negative Ion ◽  
Ionization Mass ◽  
Particle Phase ◽  
Vapor Pressures ◽  
Aerosol Mass

Abstract. We measured a large suite of gas- and particle-phase multi-functional organic compounds with a Filter Inlet for Gases and AEROsols (FIGAERO) coupled to a high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) developed at the University of Washington. The instrument was deployed on environmental simulation chambers to study monoterpene oxidation as a secondary organic aerosol (SOA) source. We focus here on results from experiments utilizing an ionization method most selective towards acids (acetate negative ion proton transfer), but our conclusions are based on more general physical and chemical properties of the SOA. Hundreds of compounds were observed in both gas and particle phases, the latter being detected by temperature-programmed thermal desorption of collected particles. Particulate organic compounds detected by the FIGAERO–HR-ToF-CIMS are highly correlated with, and explain at least 25–50 % of, the organic aerosol mass measured by an Aerodyne aerosol mass spectrometer (AMS). Reproducible multi-modal structures in the thermograms for individual compounds of a given elemental composition reveal a significant SOA mass contribution from high molecular weight organics and/or oligomers (i.e., multi-phase accretion reaction products). Approximately 50 % of the HR-ToF-CIMS particle-phase mass is associated with compounds having effective vapor pressures 4 or more orders of magnitude lower than commonly measured monoterpene oxidation products. The relative importance of these accretion-type and other extremely low volatility products appears to vary with photochemical conditions. We present a desorption-temperature-based framework for apportionment of thermogram signals into volatility bins. The volatility-based apportionment greatly improves agreement between measured and modeled gas-particle partitioning for select major and minor components of the SOA, consistent with thermal decomposition during desorption causing the conversion of lower volatility components into the detected higher volatility compounds.

scholarly journals Investigating the use of secondary organic aerosol as seed particles in simulation chamber experiments

2010 ◽  
Vol 10 (10) ◽  
pp. 25117-25151
Author(s):  
J. F. Hamilton ◽  
M. Rami Alfarra ◽  
K. P. Wyche ◽  
M. W. Ward ◽  
A. C. Lewis ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Ion Cyclotron Resonance ◽  
Photo Oxidation ◽  
Seed Particles ◽  
Aerosol Mass ◽  
Seed Aerosol ◽  
Limonene Oxidation

Abstract. The use of β-caryophyllene secondary organic aerosol particles as seeds for smog chamber simulations has been investigated. A series of experiments were carried out in the Manchester photochemical chamber as part of the Aerosol Coupling in the Earth System (ACES) project to study the effect of seed particles on the formation of secondary organic aerosol (SOA) from limonene photo-oxidation. Rather than use a conventional seed aerosol containing ammonium sulphate or diesel particles, a method was developed to use in situ chamber generated seed particles from β-caryophyllene photo-oxidation, which were then diluted to a desired mass loading (in this case 4–13 μg m-3). Limonene was then introduced into the chamber and oxidised, with the formation of SOA seen as a growth in the size of oxidised organic seed particles from 150 to 325 nm mean diameter. The effect of the partitioning of limonene oxidation products onto the seed aerosol was assessed using aerosol mass spectrometry during the experiment and the percentage of m/z 44, an indicator of degree of oxidation, increased from around 5 to 8%. The hygroscopicity of the aerosol also changed, with the growth factor for 200 nm particles increasing from less than 1.05 to 1.25 at 90% RH. The detailed chemical composition of the limonene SOA could be extracted from the complex β-caryophyllene matrix using two-dimensional gas chromatography (GC×GC) and liquid chromatography coupled to mass spectrometry. High resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICR-MS) was used to determine exact molecular formulae of the seed and the limonene modified aerosol. The average O:C ratio was seen to increase from 0.32 to 0.37 after limonene oxidation products had condensed onto the organic seed.

Characterization of organic aerosol across the Arctic land surface

2020 ◽  
Author(s):  
Imad El Haddad ◽  
Vaios Moschos ◽  
Julia Schmale ◽  
Urs Baltensperger ◽  
André S.H. Prévôt
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
Organic Compounds ◽  
Land Surface ◽  
Organic Aerosol ◽  
Anthropogenic Sources ◽  
Charge Ratio ◽  
The Arctic ◽  
Aerosol Mass ◽  
Long Time

<p>Organic compounds are of high importance in the Arctic because they contribute between one and two thirds to the submicron aerosol mass and may be co-emitted or interact with other aerosol species, such as black carbon, sulfate and metals; they also act as a vehicle of transport for persistent organic pollutants to the Arctic. Organic-containing aerosols (OA) can both absorb and scatter light, thereby changing the radiative balance, and may act as cloud condensation nuclei. OA might become increasingly important in a warming Arctic due to anthropogenic activities and natural emissions, e.g., as a result of expanded vegetation, intensified wildfires, decreasing sea ice extent and thickness leading to higher release of marine volatile organic compounds, and thawing tundra soils (permafrost) along shores and rivers. The continuous monitoring of organic carbon along with a detailed chemical analysis to determine its natural and anthropogenic sources, seasonal variability and inter-annual evolution in the Arctic is of prime importance for improved climate simulations and a realistic assessment of the effectiveness of potential mitigation or adaptation actions.</p><p>The OA chemical composition and corresponding sources remain largely unknown, partly due to the challenging measurement conditions. For example, tremendous effort is required for the deployment of online aerosol mass spectrometry at various environments for long time periods. To overcome this challenge, an offline Aerodyne aerosol mass spectrometer (AMS) technique has been introduced based on re-aerosolized liquid filter extracts. The method is capable of covering broad spatial and seasonal observations as well as determining the sources of OA (e.g. primary versus secondary, biogenic versus anthropogenic). Within the project iCUPE (Integrative and Comprehensive Understanding on Polar Environments), we extend the coverage of this technique to the most climate change sensitive region worldwide, using year-long/multi-year (from 2014 to 2019) quartz fiber filter samples collected at 8 surface stations from 68° N to 83°N, covering six Arctic Council nations including the least investigated Siberian Arctic.</p><p>Here, we present a project overview and first results from filter water extracts nebulized in Argon and measured with a high-resolution Long-Time-of-Flight AMS (average resolution ~7k). Preliminary data suggest significant variability among different sites and seasons with regard to the relative fraction of fragments-markers of certain sources, indicating largely regionally-specific sources of OA across the Arctic land surface. For example, during the same time period we observed more (roughly 90%) and more strongly oxygenated fragments (especially mass to charge ratio m/z 44) at extremely remote sites. Our average f<sub>CO2</sub> (m/z=44) of 0.26 ± 0.08 and CO<sup>+</sup>:CO<sub>2</sub><sup>+</sup> of 0.40 ± 0.14 both indicate more oxidized OA than in continental aerosols. The Van Krevelen diagram shows that the addition of carboxylic acid groups (or alcohol+carbonyl on different C atoms) with significant fragmentation may dominate the OA oxidation at high O:C. We further discuss the integration of this analysis with advanced statistical tools for factor identification on the OA fraction. Additionally, the samples will be characterized with ultra-high-resolution mass spectrometry coupled with liquid chromatography, for a two-dimensional molecular identification of primary aerosol tracers and secondary organic aerosol precursors.</p>

scholarly journals Characterization of secondary organic aerosol from heated cooking oil emissions: evolution in composition and volatility

2020 ◽  
Author(s):  
Manpreet Takhar ◽  
Yunchun Li ◽  
Arthur W. H. Chan
Keyword(s):  
Gas Phase ◽  
Organic Compounds ◽  
Secondary Organic Aerosol ◽  
Carbon Number ◽  
Complex Mixture ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Atmospheric Evolution ◽  
Oxidative Aging ◽  
Cooking Oil

Abstract. Cooking emissions account for a major fraction of urban organic aerosol. It is therefore important to understand the atmospheric evolution in the physical and chemical properties of organic compounds emitted from cooking activities. In this work, we investigate the formation of secondary organic aerosol (SOA) from oxidation of gas-phase organic compounds from heated cooking oil. The chemical composition of cooking SOA is analyzed using thermal desorption-gas chromatography-mass spectrometry. While the particle-phase composition of SOA is a highly complex mixture, we adopt a new method to achieve molecular speciation of the SOA. All the GC elutable material is classified by the constituent functional groups, allowing us to provide a molecular description of its chemical evolution upon oxidative aging. Our results demonstrate an increase in average oxidation state (from −0.6 to −0.24), and decrease in average carbon number (from 5.2 to 4.9) with increasing photochemical aging of cooking oil, suggesting that fragmentation reactions are key processes in the oxidative aging of cooking emissions within 2 days equivalent of ambient oxidant exposure. Moreover, we estimate that aldehyde precursors from cooking emissions account for a majority of the SOA formation and oxidation products. Overall, our results provide insights into the atmospheric evolution of cooking SOA, a majority of which is derived from gas-phase oxidation of aldehydes.

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