An extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF) for online measurement of atmospheric aerosol particles

Atmospheric measurement techniques, Journal Year: 2019, Volume and Issue: 12(9), P. 4867 - 4886

Published: Sept. 11, 2019

Abstract. Real-time, online measurements of atmospheric organic aerosol (OA) composition are an essential tool for determining the emissions sources and physicochemical processes governing effects on climate health. However, reliance current techniques thermal desorption, hard ionization, and/or separated collection/analysis stages introduces significant uncertainties into OA measurements, hindering progress towards these goals. To address this gap, we present a novel, field-deployable extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF), which provides online, near-molecular (i.e., molecular formula) at atmospherically relevant concentrations without analyte fragmentation or decomposition. Aerosol particles continuously sampled EESI-TOF, where they intersect spray charged droplets generated by conventional probe. Soluble components extracted then ionized as evaporated. The EESI-TOF achieves linear response to mass, with detection limits order 1 10 ng m−3 in 5 s typical compounds. In contrast systems, is not significantly affected changing matrix systems investigated. A slight decrease sensitivity increasing absolute humidity observed some ions. Although relative sensitivities variety commercially available standards vary more than factor 30, bulk secondary from individual precursor gases varies only 15. Further, ratio compound-by-compound between iodide adduct FIGAERO-I-CIMS ±50 %, suggesting that spectra indeed reflect actual distribution detectable compounds particle phase. Successful deployments laboratory environmental chamber ground-based ambient sampling, proof-of-concept aboard research aircraft highlight versatility potential system.

Language: Английский

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Organic Peroxides in Aerosol: Key Reactive Intermediates for Multiphase Processes in the Atmosphere

Chemical Reviews, Journal Year: 2023, Volume and Issue: 123(4), P. 1635 - 1679

Published: Jan. 11, 2023

Organic peroxides (POs) are organic molecules with one or more peroxide (−O–O−) functional groups. POs commonly regarded as chemically labile termination products from gas-phase radical chemistry and therefore serve temporary reservoirs for oxidative radicals (HOx ROx) in the atmosphere. Owing to their ubiquity, active gas-particle partitioning behavior, reactivity, key reactive intermediates atmospheric multiphase processes determining life cycle (formation, growth, aging), climate, health impacts of aerosol. However, there remain substantial gaps origin, molecular diversity, fate due complex nature dynamic behavior. Here, we summarize current understanding on POs, a focus identification quantification, state-of-the-art analytical developments, molecular-level formation mechanisms, chemical transformation pathways, well environmental impacts. We find that interactions SO2 transition metal ions generally fast PO pathways liquid water, lifetimes estimated be minutes hours, while hydrolysis is particularly important α-substituted hydroperoxides. Meanwhile, photolysis thermolysis likely minor sinks POs. These distinctly different fates, such reaction OH radicals, which highlights need understand By summarizing advances remaining challenges investigation propose future research priorities regarding fate,

Language: Английский

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Evaluating Organic Aerosol Sources and Evolution with a Combined Molecular Composition and Volatility Framework Using the Filter Inlet for Gases and Aerosols (FIGAERO)

Accounts of Chemical Research, Journal Year: 2020, Volume and Issue: 53(8), P. 1415 - 1426

Published: July 10, 2020

ConspectusThe complex array of sources and transformations organic carbonaceous material that comprises an important fraction atmospheric fine particle mass, known as aerosol, has presented a long running challenge for accurate predictions its abundance, distribution, sensitivity to anthropogenic activities. Uncertainties about changes in aerosol abundance over time translate uncertainties their impact on Earth's climate response air quality policy. One limitation our understanding been lack comprehensive measurements molecular composition volatility, which can elucidate processes affecting abundance. Herein we describe advances the development application Filter Inlet Gases Aerosols (FIGAERO) coupled field-deployable High-Resolution Time-of-Flight Chemical Ionization Mass Spectrometers (HRToF-CIMS). The FIGAERO HRToFCIMS combination broadly probes gas particulate OA by using programmed thermal desorption particles collected Teflon filter with subsequent detection speciation desorbed vapors inherently quantitative selected-ion chemical ionization. provides means obtain insights into volatility components thus physicochemical nature will govern evolution atmosphere.In this Account, discuss design operation FIGAERO, when HRToF-CIMS, characterization molecular-level effective laboratory field. We provide example gleaned from deployment, improve evolution. Specifically, connect profiles equilibrium saturation vapor concentration enthalpy vaporization detected components. also show how HRToF-CIMS environmental simulation chamber experiments field new constraints mechanisms governing secondary formation dynamic associated challenges decomposition during calibration both axis signal. illustrate additional through isothermal evaporation well ultrafine composition. conclude description future opportunities needs ability further science.

Language: Английский

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Organic aerosol source apportionment in Zurich using an extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF-MS) – Part 1: Biogenic influences and day–night chemistry in summer

Atmospheric chemistry and physics, Journal Year: 2019, Volume and Issue: 19(23), P. 14825 - 14848

Published: Dec. 10, 2019

Abstract. Improving the understanding of health and climate impacts aerosols remains challenging is restricted by limitations current measurement techniques. Detailed investigation secondary organic aerosol (SOA), which typically dominating fraction (OA), requires instrumentation capable real-time, in situ measurements molecular composition. In this study, we present first ambient a novel extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF-MS). The EESI-TOF-MS was deployed along with high-resolution (HR-ToF-AMS) during summer 2016 at an urban location (Zurich, Switzerland). Positive matrix factorization (PMF), implemented within Multilinear Engine (ME-2), applied to data from both instruments quantify primary contributions OA. From analysis, six-factor solution selected as most representative interpretable for investigated dataset, including two four factors. factors are dominated cooking cigarette smoke signatures while discriminated according their daytime (two factors) night-time chemistry. All showed strong influence biogenic emissions but exhibited significant day–night differences. Factors predominantly ions characteristic monoterpene sesquiterpene oxidation included less oxygenated terpene products, well organonitrates were likely derived NO3 radical monoterpenes. Overall, signal measured AMS good correlation. Further, excellent agreement terms contribution apportioned sum POA SOA total signal. However, (OOA) separated analysis flat diurnal pattern, illustrated chemical variation throughout day. captured variability, inaccessible PMF shown be consistent variations physiochemical processes influencing composition formation. improved source separation interpretability results suggest it promising approach apportionment atmospheric research.

Language: Английский

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Mass accommodation and gas–particle partitioning in secondary organic aerosols: dependence on diffusivity, volatility, particle-phase reactions, and penetration depth

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(3), P. 1565 - 1580

Published: Feb. 4, 2021

Abstract. Mass accommodation is an essential process for gas–particle partitioning of organic compounds in secondary aerosols (SOA). The mass coefficient commonly described as the probability a gas molecule colliding with surface to enter particle phase. It often applied, however, without specifying if and how deep has penetrate beneath be regarded being incorporated into condensed phase (adsorption vs. absorption). While this aspect usually not critical liquid particles rapid surface–bulk exchange, it can important viscous semi-solid or glassy solid distinguish resolve kinetics at surface, transfer across interface, further transport bulk. For purpose, we introduce novel parameter: effective αeff that depends on penetration depth function coefficient, volatility, bulk diffusivity, particle-phase reaction rate coefficient. Application traditional Fuchs–Sutugin approximation mass-transport interface yields SOA results are consistent detailed kinetic multilayer model (kinetic interactions clouds, KM-GAP; Shiraiwa et al., 2012) two-film solutions (Model Simulating Aerosol Interactions Chemistry, MOSAIC; Zaveri 2014) but deviate substantially from earlier modeling approaches considering influence related parameters. highly particles, show remains similar case low-volatility compounds, whereas decrease by several orders magnitude semi-volatile compounds. Such effects explain apparent inconsistencies between studies deriving coefficients experimental data molecular dynamics simulations. Our findings challenge approach models using fixed regardless state depth. introduced study provides efficient new way accounting reactions well regional global air quality models. limitations may planetary boundary layer (PBL), likely amorphous free upper troposphere (FT–UT) PBL low relative humidity temperature.

Language: Английский

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Molecular Understanding of the Enhancement in Organic Aerosol Mass at High Relative Humidity

Environmental Science & Technology, Journal Year: 2023, Volume and Issue: 57(6), P. 2297 - 2309

Published: Jan. 30, 2023

The mechanistic pathway by which high relative humidity (RH) affects gas–particle partitioning remains poorly understood, although many studies report increased secondary organic aerosol (SOA) yields at RH. Here, we use real-time, molecular measurements of both the gas and particle phase to provide a understanding effect RH on biogenic oxidized molecules (from α-pinene isoprene) low temperatures (243 263 K) CLOUD chamber CERN. We observe increases in SOA mass 45 85% with increasing from 10–20 60–80% 243 K, respectively, attribute it semi-volatile compounds. At measure an increase factor 2–4 concentration C10H16O2–3, while particle-phase concentrations low-volatility species, such as C10H16O6–8, remain almost constant. This results substantial shift chemical composition volatility distribution toward less oxygenated more volatile species higher (e.g., O/C ratio = 0.55 0.40, 10 80%, respectively). By modeling growth using model, accounts for kinetic limitations, can explain enhancement fraction through complementary decreased compound activity bulk-phase diffusivity. Our highlight importance water content diluting agent plasticizer growth.

Language: Английский

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Highly time-resolved chemical speciation and source apportionment of organic aerosol components in Delhi, India, using extractive electrospray ionization mass spectrometry

Atmospheric chemistry and physics, Journal Year: 2022, Volume and Issue: 22(11), P. 7739 - 7761

Published: June 15, 2022

Abstract. In recent years, the Indian capital city of Delhi has been impacted by very high levels air pollution, especially during winter. Comprehensive knowledge composition and sources organic aerosol (OA), which constitutes a substantial fraction total particulate mass (PM) in Delhi, is central to formulating effective public health policies. Previous source apportionment studies identified key primary OA (POA) showed that secondary (SOA) played major role but were unable resolve specific SOA sources. We address latter through first field deployment an extractive electrospray ionization time-of-flight spectrometer (EESI-TOF) together with high-resolution (AMS). Measurements conducted winter 2018/19, positive matrix factorization (PMF) was used separately on AMS EESI-TOF datasets apportion OA. PMF analysis yielded three two factors attributed hydrocarbon-like (HOA), biomass burning (BBOA-1 BBOA-2), more oxidized oxygenated (MO-OOA), less (LO-OOA). On average, 40 % apportioned factors. The contribution varied greatly between daytime (76.8 %, 10:00–16:00 local time (LT)) nighttime (31.0 21:00–04:00 LT). higher chemical resolution data allowed identification individual six factors, (primary cooking-related OA). remaining four predominantly origin: aromatic SOA, biogenic aged mixed urban SOA. Due uncertainties ion sensitivities, concentrations SOA-dominated related (i.e. MO-OOA + LO-OOA) multiple linear regression (MLR). Aromatic component daytime, 55.2 (42.4 Its however, decreased 25.4 (7.9 OA) nighttime. This factor oxidation light compounds emitted mostly from traffic. Biogenic accounted for 18.4 (14.2 36.1 (11.2 Aged 15.2 11.0 (11.7 8.5 mass), respectively, 15.4 22.9 (4.8 7.1 A simple dilution–partitioning model applied all estimate observed resulting photochemical production or emissions (POA). burning, found be dominated production, likely locally volatile (VOCs). contrast, diffuse regional isoprene monoterpenes. findings this study show are caused POA led traffic accounting largest fraction. Because possibly toxic than OA, its dominance suggests increased toxicity health-related consequences general public.

Language: Английский

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A 1-year characterization of organic aerosol composition and sources using an extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF)

Atmospheric chemistry and physics, Journal Year: 2020, Volume and Issue: 20(13), P. 7875 - 7893

Published: July 8, 2020

Abstract. The aerosol mass spectrometer (AMS), combined with statistical methods such as positive matrix factorization (PMF), has greatly advanced the quantification of primary organic (POA) sources and total secondary (SOA) mass. However, use thermal vaporization electron ionization yields extensive decomposition ionization-induced fragmentation, which limit chemical information needed for SOA source apportionment. recently developed extractive electrospray time-of-flight (EESI-TOF) provides spectra fraction a linear response to no or fragmentation. costs operational requirements online instruments make their impractical long-term spatially dense monitoring applications. This challenge was overcome AMS measurements by measuring re-nebulized water extracts from ambient filter samples. Here, we apply same strategy EESI-TOF 1 year 24 h samples collected approximately every fourth day throughout 2013 at an urban site. nebulized were measured simultaneously AMS. application (PMF) resolved seven factors, describe water-soluble OA: less more aged biomass burning (LABBEESI MABBEESI, respectively), cigarette-smoke-related aerosol, biological biogenic summer mixed oxygenated factor. Seasonal trends relative contributions OA compared apportionment ions, cellulose, meteorological data. Cluster analysis utilized identify key factor-specific ions based on PMF. Both LABB MABB contribute strongly during winter. is distinguished very high signals C6H10O5 (levoglucosan isomers) C8H12O6, whereas characterized large number CxHyOz CxHyOzN species two distinct populations: one low H:C O:C other O:C. Two summertime attributed terpene-derived SOA, major in central Europe. Furthermore, factor identified, dominated plant-derived fatty acids correlated free cellulose. contained contribution nicotine abundance nitrate m∕z.

Language: Английский

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Superoxide Formation from Aqueous Reactions of Biogenic Secondary Organic Aerosols

Environmental Science & Technology, Journal Year: 2020, Volume and Issue: 55(1), P. 260 - 270

Published: Dec. 22, 2020

Reactive oxygen species (ROS) play a central role in aqueous-phase processing and health effects of atmospheric aerosols. Although hydroxyl radical (•OH) hydrogen peroxide (H2O2) are regarded as major oxidants associated with secondary organic aerosols (SOA), the kinetics reaction mechanisms superoxide (O2•–) formation rarely quantified poorly understood. Here, we demonstrate dominant O2•– molar yields 0.01–0.03% from aqueous reactions biogenic SOA generated by •OH photooxidation isoprene, β-pinene, α-terpineol, d-limonene. The temporal evolution is elucidated kinetic modeling cascade including decomposition hydroperoxides, oxidation primary or alcohols, unimolecular α-hydroxyperoxyl radicals. Relative various types ROS reflect relative abundance hydroperoxides alcohols contained SOA. These findings mechanistic understanding have important implications on fate particle-phase highly oxygenated molecules well oxidative stress upon respiratory deposition.

Language: Английский

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Global simulations of monoterpene-derived peroxy radical fates and the distributions of highly oxygenated organic molecules (HOMs) and accretion products

Atmospheric chemistry and physics, Journal Year: 2022, Volume and Issue: 22(8), P. 5477 - 5494

Published: April 26, 2022

Abstract. We evaluate monoterpene-derived peroxy radical (MT-RO2) unimolecular autoxidation and self- cross-reactions with other RO2 species in the GEOS-Chem global chemical transport model. The formation of associated highly oxygenated organic molecules (HOMs) accretion products are tracked competition bimolecular reactions. Autoxidation is dominant fate up to 6–8 km for first-generation MT-RO2, which can undergo H shifts. Reaction NO be a more common H-shift rate constants < 0.1 s−1 or at altitudes higher than 8 due imposed Arrhenius temperature dependence For MT-derived HOM-RO2, generated by multistep reaction predicted major throughout most boreal tropical forest regions, whereas dominates temperate subtropical forests Northern Hemisphere. newly added reactions result an approximate 4 % average decrease HO2 RO2, mainly faster self-/cross-reactions but impact upon HO2, OH, NOx abundances only important planetary boundary layer (PBL) over portions forests. Predicted HOM concentrations MT-rich regions seasons exceed total aerosol standard version model depending on parameters used. Comparisons observations reveal that large uncertainties remain key processes, especially respect photochemical lifetime volatility HOMs as well rates branching products. Further laboratory studies related MT-RO2-derived gas-phase product kinetics – their atmospheric fate, such gas–particle partitioning, multiphase chemistry, net secondary needed.

Language: Английский

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