Analysis of Secondary Organic Aerosol from Isoprene and Butadiene with Hyphenated Mass Spectrometry

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Total Pages : 0 pages
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Book Synopsis Analysis of Secondary Organic Aerosol from Isoprene and Butadiene with Hyphenated Mass Spectrometry by : Klara Nestorowicz (chemia)

Download or read book Analysis of Secondary Organic Aerosol from Isoprene and Butadiene with Hyphenated Mass Spectrometry written by Klara Nestorowicz (chemia) and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Characterization of the Molecular Composition of Secondary Organic Aerosols Using High Resolution Mass Spectrometry

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ISBN 13 :
Total Pages : 274 pages
Book Rating : 4.:/5 (839 download)

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Book Synopsis Characterization of the Molecular Composition of Secondary Organic Aerosols Using High Resolution Mass Spectrometry by : Rachel Elizabeth Sellon

Download or read book Characterization of the Molecular Composition of Secondary Organic Aerosols Using High Resolution Mass Spectrometry written by Rachel Elizabeth Sellon and published by . This book was released on 2012 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atmospheric aerosols can affect visibility and the Earth's climate by scattering and absorbing light and they also can have adverse effects on human health. The organic portion of atmospheric aerosols is very complex and is a major fraction of fine particulate matter. High molecular weight (high-MW)/oligomeric organic compounds can make up a large part of this organic fraction and the composition, sources, and formation mechanisms for these compounds are not well understood. This knowledge and understanding is necessary to decrease the uncertainty in the climate affects of aerosols and to improve climate models. This dissertation investigates the composition and formation mechanisms for the high-MW/oligomeric fraction of secondary organic aerosols (SOA) collected in Bakersfield, CA and presents a comparative analysis of chamber and ambient SOA, from both Los Angeles (LA) and Bakersfield, to investigate sources at both locations. A novel sampling technique, nanospray-Desorption Electrospray Ionization (nano-DESI), was used with high resolution mass spectrometry (HR-MS) to determine the molecular formulas of the high molecular weight (HMW)/oligomeric fraction of SOA. Nano-DESI involves direct desorption from the sample surface and was used to limit reactions that can take place with extraction and storage in solvent. The samples were collected in Bakersfield and LA during CalNex 2010. Both Bakersfield and LA are out of compliance with EPA standards of ozone and particulate matter and provide opportunities to examine air masses affected by both anthropogenic and biogenic sources. This dissertation has provided the first evidence of observable changes in the composition of high-MW/oligomeric compounds throughout the day. Using positive mode nano-DESI, afternoon increases in the number of compounds that contain carbon, hydrogen and oxygen (CHO) were observed consistent with photochemistry/ozonolysis as a major source for these compounds. Compounds containing reduced nitrogen groups were dominant at night and had precursors consistent with imine formation products from the reaction of carbonyls and ammonia. In the negative mode, organonitrates (CHON) and nitroxy organosulfates (CHONS) had larger numbers of compounds in the night/morning samples consistent with nitrate radical formation reactions. A subset of the CHONS compounds and compounds containing sulfur (CHOS) had the same composition as known biogenic organosulfates and nitroxy organosulfates indicating contributions from both biogenic and anthropogenic sources to the SOA. This dissertation also provides the first analysis of the high-MW/oligomeric fraction in size resolved samples; the majority of the compounds were found in aerosol diameters between 0.18-1.0 micrometers and the CHON were bimodal with size. Finally, this dissertation presents the first comparative analysis of the overlap in the composition of this fraction of SOA between ambient and chamber samples. Samples collected in Pasadena, LA and Bakersfield were compared with samples collected in a smog chamber using diesel and isoprene sources. The results indicate that diesel had the highest overlap at both sites, Bakersfield samples were more oxidized, and LA showed evidence of a SOA plume arriving from downtown LA. The addition of ammonia to the diesel chamber experiment was necessary to form many of the 2N compounds found in Bakersfield. These results increase our understanding of the types of compounds found in urban environments and give evidence for the timescales of formation reactions in an ambient environment. They show that the majority of the high-MW oligomeric compounds are found in submicron size particles and that the composition of this fraction of SOA varies with aerosol size. Results from the chamber comparisons show that both diesel and isoprene are important sources for these compounds and also that there other sources are present. Future work that combines this type of analysis, in other ambient environments, with studies of the optical properties of aerosols could be used to help improve climate models and to start to close the gap in our understanding of the climate effects of atmospheric aerosols.

Characterization of Biogenic Secondary Organic Aerosol Using Mass Spectrometry

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ISBN 13 : 9781124086231
Total Pages : pages
Book Rating : 4.0/5 (862 download)

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Book Synopsis Characterization of Biogenic Secondary Organic Aerosol Using Mass Spectrometry by : Katherine J. Heaton

Download or read book Characterization of Biogenic Secondary Organic Aerosol Using Mass Spectrometry written by Katherine J. Heaton and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Secondary Organic Aerosol (SOA) forms in the atmosphere from the oxidation of biogenic emissions. Even though SOA has been linked to health and climate effects, the chemical mechanism of SOA formation is not well understood. Through the use of mass spectrometry, this work characterizes SOA during the early stages of growth from the reaction of ozone with monoterpenes, a major biogenic emission. In this thesis, three types of studies are described for analyzing SOA formation: (1) the molecular composition of SOA is studied using the photoionization aerosol mass spectrometer, (2) the atomic composition is studied with the nanometer aerosol mass spectrometer and (3) high resolution mass spectrometry is used to help reconcile atomic and molecular composition data. The monoterpene ozonolysis reactions were performed in a flow tube reactor, where the reaction period could vary from 3s to 22s. The Photoionization Aerosol Mass Spectrometer (PIAMS) detected the formation of oligomers within seconds of the onset of the reaction. Ions that were detected were mapped to dimers that could form via the stabilized Criegee intermediate channel or the hydroperoxy channel. The Nanometer Aerosol Mass Spectrometer (NAMS) analyzed the elemental composition of the SOA which showed the formation of highly polar compounds during the early stages of SOA growth. NAMS also analyzed the changes in the composition of SOA when it formed in the presence of atmospheric species (water vapor, nitric acid vapor and sodium chloride seed particles). The data collected indicated that there is not as much change for endocyclic compounds as there is for exocyclic compounds. Finally, a new off-line analysis technique was created to micro-extract SOA deposited on a plate from the flow tube reactor. The samples were analyzed with the Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FTICR-MS). The FTICR-MS was used to collect molecular and elemental data simultaneously. The FTICR-MS produced accurate mass data that could be used to calculate molecular formulas. This provided a direct comparison of the data acquired with PIAMS and NAMS.

A Molecular Characterization of Biogenic Secondary Organic Aerosol by High-resolution Time-of-flight Mass Spectrometry

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ISBN 13 :
Total Pages : 178 pages
Book Rating : 4.:/5 (932 download)

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Book Synopsis A Molecular Characterization of Biogenic Secondary Organic Aerosol by High-resolution Time-of-flight Mass Spectrometry by : Felipe Daniel Lopez-Hilfiker

Download or read book A Molecular Characterization of Biogenic Secondary Organic Aerosol by High-resolution Time-of-flight Mass Spectrometry written by Felipe Daniel Lopez-Hilfiker and published by . This book was released on 2015 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: The guiding question to this research is: To what extent and by what mechanisms do biogenic volatile organic compounds contribute to atmospheric aerosol mass? To address this question we need to understand the chemistry that produces condensable vapors which when in the presence of particles may partition onto the aerosol surface depending on their chemical and physical properties. I developed an insitu gas and aerosol sampling system, the FIGAERO (Filter Inlet for Gases and AEROsol) to speciate gas and particle phase organics derived from photochemical reactions with biogenic volatile organic compounds under both field and laboratory conditions. By coupling the FIGAERO to a High-Resolution Time-of-Flight Chemical Ionization Mass Spectrometer (HR-TOF-CIMS) I am able to elucidate chemical pathways by identifying elemental compositions and in some cases functional groups present in the detected molecular ions. The coupling of the FIGAERO to the HR-TOF-CIMS also allows the estimation of effective vapor pressures of the aerosol components and this information can be used to improve vapor pressure models and test associated partitioning theories and parameterizations. The approach also provides hundreds of speciated chemical tracers that can be correlated with traditional environmental and chemical measurements (e.g AMS, NOx, SO2, SMPS, VOC) to help derive sources and sinks and to constrain the mechanisms responsible for the formation and growth of organic aerosol. Measurements obtained across a wide range of conditions and locations allowing connections and contrasts between different chemical systems, providing insights into generally controlling factors of secondary organic aerosol (SOA) and its properties.

Molecular Composition, Volatility, and Formation Mechanisms of Biogenic Secondary Organic Aerosol

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ISBN 13 :
Total Pages : 129 pages
Book Rating : 4.:/5 (19 download)

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Book Synopsis Molecular Composition, Volatility, and Formation Mechanisms of Biogenic Secondary Organic Aerosol by : Emma Louise D'Ambro

Download or read book Molecular Composition, Volatility, and Formation Mechanisms of Biogenic Secondary Organic Aerosol written by Emma Louise D'Ambro and published by . This book was released on 2018 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Complex Mixtures

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ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (111 download)

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Book Synopsis Complex Mixtures by : Emma Quinn Walhout

Download or read book Complex Mixtures written by Emma Quinn Walhout and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Complex organic mixtures in the environment can contain hundreds to thousands of different organic molecules, and their composition and reactivity can have important environmental implications. In addition to gases, the atmosphere is made of a variety of small liquids and solids called aerosols. These aerosols have large impacts on human health, climate, and atmospheric chemical reactions. Here, secondary organic aerosol (SOA) from the ozonolysis of [alpha]-pinene is characterized. The atmospheric lifetime of SOA is very uncertain, but recent laboratory and modeling studies have demonstrated that photolysis is potentially an important process for organic mass loss from aerosol particles.1-5 Photolysis modifies the molecular composition and properties of aerosols through photolytic cleaving and repartitioning of volatile products. Characterization of dry, irradiated SOA can provide insights into photolysis driven changes in absorption properties and chemical composition. These results illuminate aging mechanisms and chemical and physical properties of organic aerosols in order to improve atmospheric modeling and the understanding of atmospheric chemical reactions. However, the high chemical complexity and low atmospheric abundance presents a difficult analytical challenge. Milligrams, or more, of material may be needed for speciated spectroscopic analysis.6 This study used a suite of advanced analytical techniques, including a novel combination of action spectroscopy and mass spectrometry that provides more structural information on organic mixtures than mass spectrometry alone. This study also used tunable light from a free electron laser, infrared and UV/Vis absorption, and computational chemistry to characterize molecules in [alpha]-pinene SOA. In addition, complex organic mixtures are also found in particulate matter that has deposited onto Earth’s surface. The preliminary results of dew analysis, including a foundation method of analysis for future study, gives the first look at organic material deposited into dew water on natural surfaces. This offers insight into atmospheric organic deposition to better understand chemical transport, air quality, and carbon cycling in the atmosphere.

Quantitative Analysis of Secondary Organic Aerosol Using a High-resolution Mass Spectral Database

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ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (119 download)

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Book Synopsis Quantitative Analysis of Secondary Organic Aerosol Using a High-resolution Mass Spectral Database by : William J. Dixon

Download or read book Quantitative Analysis of Secondary Organic Aerosol Using a High-resolution Mass Spectral Database written by William J. Dixon and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Analysis of Organic Aerosol in Houston, TX, Through Aerosol Mass Spectrometry and Proton Nuclear Magnetic Resonance Spectroscopy

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ISBN 13 :
Total Pages : 110 pages
Book Rating : 4.:/5 (31 download)

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Book Synopsis Analysis of Organic Aerosol in Houston, TX, Through Aerosol Mass Spectrometry and Proton Nuclear Magnetic Resonance Spectroscopy by : Meredith J. Cleveland

Download or read book Analysis of Organic Aerosol in Houston, TX, Through Aerosol Mass Spectrometry and Proton Nuclear Magnetic Resonance Spectroscopy written by Meredith J. Cleveland and published by . This book was released on 2009 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Analysis of the Chemical Composition of Secondary Organic Aerosol

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ISBN 13 :
Total Pages : 241 pages
Book Rating : 4.:/5 (427 download)

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Book Synopsis Analysis of the Chemical Composition of Secondary Organic Aerosol by : Mirjam Sax

Download or read book Analysis of the Chemical Composition of Secondary Organic Aerosol written by Mirjam Sax and published by . This book was released on 2005 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Secondary Organic Aerosol Composition Studies Using Mass Spectrometry

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ISBN 13 :
Total Pages : 772 pages
Book Rating : 4.:/5 (919 download)

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Book Synopsis Secondary Organic Aerosol Composition Studies Using Mass Spectrometry by : Katherine Ann Schilling

Download or read book Secondary Organic Aerosol Composition Studies Using Mass Spectrometry written by Katherine Ann Schilling and published by . This book was released on 2015 with total page 772 pages. Available in PDF, EPUB and Kindle. Book excerpt: Trace volatile organic compounds emitted by biogenic and anthropogenic sources into the atmosphere can undergo extensive photooxidation to form species with lower volatility. By equilibrium partitioning or reactive uptake, these compounds can nucleate into new aerosol particles or deposit onto already-existing particles to form secondary organic aerosol (SOA). SOA and other atmospheric particulate matter have measurable effects on global climate and public health, making understanding SOA formation a needed field of scientific inquiry. SOA formation can be done in a laboratory setting, using an environmental chamber; under these controlled conditions it is possible to generate SOA from a single parent compound and study the chemical composition of the gas and particle phases. By studying the SOA composition, it is possible to gain understanding of the chemical reactions that occur in the gas phase and particle phase, and identify potential heterogeneous processes that occur at the surface of SOA particles. In this thesis, mass spectrometric methods are used to identify qualitatively and qualitatively the chemical components of SOA derived from the photooxidation of important anthropogenic volatile organic compounds that are associated with gasoline and diesel fuels and industrial activity (C12 alkanes, toluene, and o-, m-, and p-cresols). The conditions under which SOA was generated in each system were varied to explore the effect of NOx and inorganic seed composition on SOA chemical composition. The structure of the parent alkane was varied to investigate the effect on the functionalization and fragmentation of the resulting oxidation products. Relative humidity was varied in the alkane system as well to measure the effect of increased particle-phase water on condensed-phase reactions. In all systems, oligomeric species, resulting potentially from particle-phase and heterogeneous processes, were identified. Imines produced by reactions between (NH4)2SO4 seed and carbonyl compounds were identified in all systems. Multigenerational photochemistry producing low- and extremely low-volatility organic compounds (LVOC and ELVOC) was reflected strongly in the particle-phase composition as well.

Investigating Sources and Sinks of Organic Aerosols

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ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (742 download)

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Book Synopsis Investigating Sources and Sinks of Organic Aerosols by : Alan J. Kwan

Download or read book Investigating Sources and Sinks of Organic Aerosols written by Alan J. Kwan and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Secondary organic aerosol (SOA) are important components in atmospheric processes and significantly impact human health. The complexity of SOA composition and formation processes has hampered efforts to fully characterize their impacts, and to predict how those impacts will be affected by changes in climate and human activity. Here, we explore SOA formation in the laboratory by coupling an environmental chamber with a suite of analytical tools, including a gas-phase mass spectrometry technique that is well suited for tracking the hydrocarbon oxidation processes that drive SOA formation. Focusing on the oxidation of isoprene by the nitrate radical, NO3, we find that reactions of peroxy radicals (RO2) to form ROOR dimers is an important process in SOA formation. The other gas-phase products of these RO2 reactions differ from what is expected from studies of simpler radicals, indicating that more studies are necessary to fully constrain RO2 chemistry. Finally, we examine the role of heterogeneous oxidation as a sink of organic aerosol and a source of oxygenated volatile organic compounds in the free troposphere.

Characterization of Secondary Organic Aerosols in the Atmosphere by Using Mass Spectrometric Approaches

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ISBN 13 :
Total Pages : 103 pages
Book Rating : 4.:/5 (866 download)

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Book Synopsis Characterization of Secondary Organic Aerosols in the Atmosphere by Using Mass Spectrometric Approaches by : Farhat Yasmeen

Download or read book Characterization of Secondary Organic Aerosols in the Atmosphere by Using Mass Spectrometric Approaches written by Farhat Yasmeen and published by . This book was released on 2010 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt: Secondary organic aerosol (SOA) accounts for a significant fraction of ambient tropospheric aerosol. The chemical composition of SOA is highly uncertain as it depends on different ongoing chemical and physical processes of biogenic volatile organic compounds (BVOC) and anthropogenic volatile organic compounds in the atmosphere. The research performed within the frame of this doctoral thesis is focused on the characterization of SOA produced from BVOC under a variety of atmospheric reactions resorting to mass spectrometric approaches. In a first study, the aqueous-phase oligomer formation of a major atmospheric photooxidation product, i.e., methylglyoxal, has been investigated to explore an additional pathway producing SOA through cloud processes during night-time. A second study deals with the chemical characterization (sulfate and organic matter) of marine aerosols. methanesulfonic acid was the dominating organic compound in in the fine size fraction of aerosol. A third study concerns the structural characterization of a dimeric [alpha]- and [beta]-pinene SOA product. It is proposed that diaterpenylic acid is a key monomeric unit for dimers of the ester type. A fourth study deals with the chemical characterization by fragmentation of major terpenoic acids in ambient fine aerosols from a rural site. Emphasis is given to the mass spectrometric differentiation of isobaric terpenoic acids that occur in fine forest aerosol. This thesis presents results on aerosol characterization from a wide range of parent organic compounds under a variety of atmospheric conditions.

Soft Ionization Aerosol Mass Spectrometry of Complex Organics

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Publisher : LAP Lambert Academic Publishing
ISBN 13 : 9783846507964
Total Pages : 248 pages
Book Rating : 4.5/5 (79 download)

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Book Synopsis Soft Ionization Aerosol Mass Spectrometry of Complex Organics by : Scott Geddes

Download or read book Soft Ionization Aerosol Mass Spectrometry of Complex Organics written by Scott Geddes and published by LAP Lambert Academic Publishing. This book was released on 2011-09 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerosol Mass Spectrometry (AMS) has emerged as the principal tool for aerosol analysis and soft ionization techniques are an important subset particularly suited for chemical speciation investigations. This dissertation presents the use of soft ionization AMS for the analysis of complex organic aerosols in laboratory studies, both as models for Primary and Secondary Organic Aerosol (POA and SOA). An established technique (PERCI-AMS) is used to identify the resonance capture mechanisms for cysteine containing peptide residues. This technique is then applied to investigate the ozonolysis of mixed particles representative of biogenic rich organic aerosol as is common for marine aerosols. In order to apply soft ionization AMS to lower concentrations of particle mass more representative of ambient aerosol loadings and thus allow SOA investigations, an entirely new AMS technique was developed and is presented utilizing Near-Infrared Laser-Desorption-Ionization (NIR-LDI-AMS). The advantages this technique are exemplified by an analysis of limonene ozonolysis SOA whereby first generation homogeneous oxidation products are delineated from second generation heterogeneous oxidation products.

Laboratory Studies on the Formation of Secondary Organic Aerosol from the Atmospheric Oxidation of Alkenes

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ISBN 13 :
Total Pages : 626 pages
Book Rating : 4.3/5 (121 download)

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Book Synopsis Laboratory Studies on the Formation of Secondary Organic Aerosol from the Atmospheric Oxidation of Alkenes by : Kenneth Stephen Docherty

Download or read book Laboratory Studies on the Formation of Secondary Organic Aerosol from the Atmospheric Oxidation of Alkenes written by Kenneth Stephen Docherty and published by . This book was released on 2004 with total page 626 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Chemical and Physical Characterization of Secondary Organic Aerosol Formation from Select Agricultural Emissions

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ISBN 13 :
Total Pages : 414 pages
Book Rating : 4.3/5 (121 download)

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Book Synopsis Chemical and Physical Characterization of Secondary Organic Aerosol Formation from Select Agricultural Emissions by : Quentin Gerald James Malloy

Download or read book Chemical and Physical Characterization of Secondary Organic Aerosol Formation from Select Agricultural Emissions written by Quentin Gerald James Malloy and published by . This book was released on 2009 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Enabling the Identification, Quantification, and Characterization of Organics in Complex Mixtures to Understand Atmospheric Aerosols

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ISBN 13 :
Total Pages : 167 pages
Book Rating : 4.:/5 (919 download)

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Book Synopsis Enabling the Identification, Quantification, and Characterization of Organics in Complex Mixtures to Understand Atmospheric Aerosols by : Gabriel Avram Isaacman

Download or read book Enabling the Identification, Quantification, and Characterization of Organics in Complex Mixtures to Understand Atmospheric Aerosols written by Gabriel Avram Isaacman and published by . This book was released on 2014 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: Particles in the atmosphere are known to have negative health effects and important but highly uncertain impacts on global and regional climate. A majority of this particulate matter is formed through atmospheric oxidation of naturally and anthropogenically emitted gases to yield highly oxygenated secondary organic aerosol (SOA), an amalgamation of thousands of individual chemical compounds. However, comprehensive analysis of SOA composition has been stymied by its complexity and lack of available measurement techniques. In this work, novel instrumentation, analysis methods, and conceptual frameworks are introduced for chemically characterizing atmospherically relevant mixtures and ambient aerosols, providing a fundamentally new level of detailed knowledge on their structures, chemical properties, and identification of their components. This chemical information is used to gain insights into the formation, transformation and oxidation of organic aerosols. Biogenic and anthropogenic mixtures are observed in this work to yield incredible complexity upon oxidation, producing over 100 separable compounds from a single precursor. As a first step toward unraveling this complexity, a method was developed for measuring the polarity and volatility of individual compounds in a complex mixture using two-dimensional gas chromatography, which is demonstrated in Chapter 2 for describing the oxidation of SOA formed from a biogenic compound (longifolene: C15H24). Several major products and tens of substantial minor products were produced, but none could be identified by traditional methods or have ever been isolated and studied in the laboratory. A major realization of this work was that soft ionization mass spectrometry could be used to identify the molecular mass and formula of these unidentified compounds, a major step toward a comprehensive description of complex mixtures. This was achieved by coupling gas chromatography to high resolution time-of-flight mass spectrometry with vacuum ultraviolet (VUV) photo-ionization. Chapters 3 and 4 describe this new analytical technique and its initial application to determine the structures of unknown compounds and formerly unresolvable mixtures, including a complete description of the chemical composition of two common petroleum products related to anthropogenic emissions: diesel fuel and motor oil. The distribution of hydrocarbon isomers in these mixtures - found to be mostly of branched, cyclic, and saturated - is described with unprecedented detail. Instead of measuring average bulk aerosol properties, the methods developed and applied in this work directly measure the polarity, volatility, and structure of individual components to allow a mechanistic understanding of oxidation processes. Novel characterizations of these complex mixtures are used to elucidate the role of structure and functionality in particle-phase oxidation, including in Chapter 4 the first measurements of relative reaction rates in a complex hydrocarbon particle. Molecular structure is observed to influence particle-phase oxidation in unexpected and important ways, with cyclization decreasing reaction rates by ~30% and branching increasing reaction rates by ~20-50%. The observed structural dependence is proposed to result in compositional changes in anthropogenic organic aerosol downwind of urban areas, which has been confirmed in subsequent work by applying the techniques described here. Measurement of organic aerosol components is extended to ambient environments through the development of instrumentation with the unprecedented capability to measure hourly concentrations and gas/particle partitioning of individual highly oxygenated organic compounds in the atmosphere. Chapters 5 and 6 describe development of new procedures and hardware for the calibration and analysis of oxygenates using the Semi-Volatile Thermal desorption Aerosol Gas chromatograph (SV-TAG), a custom instrument for in situ quantification of gas- and particle-phase organic compounds in the atmosphere. High time resolution measurement of oxygenated compounds is achieved through a reproducible and quantitative methodology for in situ "derivatization"--Replacing highly polar functional groups that cannot be analyzed by traditional gas chromatography with less polar groups. Implementation of a two-channel sampling system for the simultaneous collection of particle-phase and total gas-plus-particle phase samples allows for the first direct measurements of gas/particle partitioning in the atmosphere, significantly advancing the study of atmospheric composition and variability, as well as the processes governing condensation and re-volatilization. This work presents the first in situ measurements of a large suite of highly oxygenated biogenic oxidation products in both the gas- and particle-phase. Isoprene, the most ubiquitous biogenic emission, oxidizes to form 2-methyltetrols and C5 alkene triols, while [alpha]-pinene, the most common monoterpene, forms pinic, pinonic, hydroxyglutaric, and other acids. These compounds are reported in Chapter 7 with unprecedented time resolution and are shown for the first time to have a large gas-phase component, contrary to typical assumptions. Hourly comparisons of these products with anthropogenic aerosol components elucidate the interaction of human and natural emissions at two rural sites: the southeastern, U.S. and Amazonia, Brazil. Anthropogenic influence on SOA formation is proposed to occur through the increase in liquid water caused by anthropogenic sulfate. Furthermore, these unparalleled observations of gas/particle partitioning of biogenic oxidation products demonstrate that partitioning of oxygenates is unexpectedly independent of volatility: many volatile, highly oxygenated compounds have a large particle-phase component that is poorly described by traditional models. These novel conclusions are reached in part by applying the new frameworks developed in previous chapters to understand the properties of unidentified compounds, demonstrating the importance of detailed characterization of atmospheric organic mixtures. Comprehensive analysis of anthropogenic and biogenic emissions and oxidation product mixtures is coupled in this work with high time-resolution measurement of individual organic components to yield significant insights into the transformations of organic aerosols. Oxidation chemistry is observed in both laboratory and field settings to depend on molecular properties, volatility, and atmospheric composition. However, this work demonstrates that these complex processes can be understood through the quantification of individual known and unidentified compounds, combined with their classification into descriptive frameworks.

Environmental Chamber Study of Atmospheric Chemistry and Secondary Organic Aerosol Formation Using Cavity Enhanced Absorption Spectroscopy

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ISBN 13 : 9781124940335
Total Pages : 76 pages
Book Rating : 4.9/5 (43 download)

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Book Synopsis Environmental Chamber Study of Atmospheric Chemistry and Secondary Organic Aerosol Formation Using Cavity Enhanced Absorption Spectroscopy by : Yingdi Liu

Download or read book Environmental Chamber Study of Atmospheric Chemistry and Secondary Organic Aerosol Formation Using Cavity Enhanced Absorption Spectroscopy written by Yingdi Liu and published by . This book was released on 2011 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis is only a part of my research work. For more information about my other work, including cavity ring down spectroscopy studies for peroxy radical, aerosol optical extinction, transparent thin and time of flight mass spectrometry studies for the initial steps of ozone and alkenes reaactions, please refer to my PhD thesis in Chemistry department, UC-Riverside.