Characterization of Secondary Organic Aerosol Precursors Using Two-Dimensional Gas Chromatography with Time of Flight Mass Spectrometry (GC×GC/TOFMS) PDF Download
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Author: Publisher: ISBN: Category : Air Languages : en Pages : 64
Book Description
The oxidation of volatile organic compounds (VOCs) plays a role in both regional and global air quality through the formation of secondary organic aerosols (SOA). More than 1000TgC/yr of non-methane VOCs are emitted from biogenic sources (significantly greater than from anthropogenic sources). Despite this magnitude and potential importance for air quality, the body of knowledge around the identities, quantities and oxidation processes of these compounds is still incomplete (e.g., Goldstein & Galbally, 2007; Robinson et al., 2009). Two-dimensional gas chromatography paired with time-of-flight mass spectrometry (GC×GC/TOFMS) is a powerful analytical technique which is explored here for its role in better characterizing biogenic VOCs (BVOCs) and thus SOA precursors.
Author: Publisher: ISBN: Category : Air Languages : en Pages : 64
Book Description
The oxidation of volatile organic compounds (VOCs) plays a role in both regional and global air quality through the formation of secondary organic aerosols (SOA). More than 1000TgC/yr of non-methane VOCs are emitted from biogenic sources (significantly greater than from anthropogenic sources). Despite this magnitude and potential importance for air quality, the body of knowledge around the identities, quantities and oxidation processes of these compounds is still incomplete (e.g., Goldstein & Galbally, 2007; Robinson et al., 2009). Two-dimensional gas chromatography paired with time-of-flight mass spectrometry (GC×GC/TOFMS) is a powerful analytical technique which is explored here for its role in better characterizing biogenic VOCs (BVOCs) and thus SOA precursors.
Author: Publisher: ISBN: Category : Atmospheric aerosols Languages : en Pages : 30
Book Description
In the atmosphere, biogenic and anthropogenic emissions are oxidized to form secondary organic aerosols (SOA); however, the identities and concentrations of the compounds formed are inadequately known. In this work an aerosol (gas+particle) collection system was designed and tested in order to more fully characterize atmospheric volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) that contribute to SOA. Target compounds to be collected were C6 to C20 compounds with oxygenated functional groups such as aldehydes and alcohols. The collection system was designed to allow characterization of atmospheric aerosols using multiple analytical methods: two-dimensional gas chromatography with time of flight-mass spectrometry (GCxGC-TOFMS), with and without derivatization, and two- dimensional liquid chromatography with mass spectrometry (LCxLC-MS). The first stage of collection in the system uses a polytetrafluoroethelyne (PTFE) filter to capture the low volatility compounds in the particle phase. The flow is then split for two different collection mechanisms: adsorption thermal desorption (ATD) cartridges for gas phase VOCs, and solid phase extraction (SPE) filters for SVOCs. In order to test the viability of aerosol collection on PTFE filters and subsequent analysis using derivatization, four aerosol samples were collected on PTFE filters at Reed College. The average mass collected over 4 trials was 10.15 [microgram]. The U.S. Department of Energy Environmental and Molecular Science Lab (EMSL) performed extraction and derivatization on the Reed College samples, followed by GC-MS. Results show identifiable peaks that are significantly different than the filter blanks, suggesting that derivatization methods can be used to facilitate identification of relatively polar organic compounds sampled onto PTFE filters. Additional aerosol collection trials were conducted at Portland State University (PSU) using two SPE filters in series to collect gases and particles from tobacco smoke. A literature review was conducted to determine the type of SPE filter, time, and necessary flow rates to collect an optimum amount of sample for analysis. The tobacco smoke PM mass collected was 6mg/2mg and 2mg/0.9mg for trials one and two, respectively (front/back filter). PSU tobacco smoke samples were analyzed at EMSL using GC-MS with derivatization. Results showed successful collection of polar compounds in the semi-volatile range of interest, including alcohols, aldehydes, and phenols. Next steps of this research include collecting aerosol samples with the whole system (PTFE + ATD + SPE) and subsequent analysis of samples using GCxGC-TOFMS, with and without derivatization, and LCxLC-MS. Results to date suggest a more complete characterization of atmospheric organic aerosols can be attained using multiple offline analyses. Further characterization of atmospheric organic aerosols is necessary to improve air quality and climate modeling and develop efficient air quality and climate change mitigation technologies.
Author: Yaping Zhang Publisher: ISBN: Category : Electronic dissertations Languages : en Pages : 207
Book Description
Atmospheric organic aerosols are composed of thousands of individual compounds, interacting with climate through changes in aerosol optical properties and cloud interactions, and can be detrimental to human health. Aerosol mass spectrometry (MS) and gas chromatography (GC)-separated MS measurements have been utilized to better characterize the chemical composition of this material that comes from a variety of sources and experiences continuous oxidation while in the atmosphere. This dissertation describes the development of a novel rapid data analysis method for grouping of major components within chromatography-separated measurements and first application using thermal desorption aerosol gas chromatograph (TAG) -- MS data. Chromatograms are binned and inserted directly into a positive matrix factorization (PMF) analysis to determine major contributing components, eliminating the need for manual compound integrations of hundreds of resolved molecules, and incorporating the entirety of the eluting MS signal, including Unresolved Complex Mixtures (UCM) and decomposition products that are often ignored in traditional GC-MS analysis. Binned GC-MS data has three dimensions: (1) mass spectra index m/z, (2) bin number, and (3) sample number. PMF output is composed of two dimensions; factor profiles and factor time series. The specific arrangement of the input data (three dimensions of variation structured as a two dimensional matrix) in a two dimensional PMF analysis affects the structure of the PMF profiles and time series output. If mass spectra index is in the profile dimension, and bin number and sample number are in the time series dimension, PMF groups components into factors with similar mass spectra, such as major contributing individual compounds, UCM with similar functional composition, and homologous compound series. This type of PMF analysis is described as the binning method for chromatogram deconvolution, and is presented in Chapter 2. If the sample number is in the time series dimension, and the bin number and mass spectra index, arranged as mass spectra resolved retention time/chromatogram (bin number), are in the profile dimension, PMF groups components with similar time series trends. This type of PMF analysis is described as binning method for source apportionment, and is described in Chapter 3. The binning methods are compared to traditional compound integration methods using previously-collected hourly ambient samples from Riverside, CA during the 2005 Study of Organic Aerosols at Riverside (SOAR) field campaign, as discussed in Chapters 2-3. Further application of the binning method for source apportionment is performed on newly acquired hourly TAG data from East St. Louis, IL, operated as part of the 2013 St. Louis Air Quality Regional Study (SLAQRS). Major sources of biogenic secondary organic aerosol (SOA), anthropogenic primary organic aerosol (POA) were identified, as described in detail in Chapter 4. Finally, our PMF separation method was tested for reliability using primary and secondary sources in a controlled laboratory system. As shown in Chapter 5, we find that for application of PMF on receptor measurements, high signal intensity and unique measurement profiles, like those found in TAG chromatograms, are keys to successful source apportionment. The binning method with component separation by PMF may be a valuable analysis technique for other complex data sets that incorporate measurements (e.g., mass spectrometry, spectroscopy, etc.) with additional separations (e.g., volatility, hygroscopicity, electrical mobility, etc.).
Author: Felipe Daniel Lopez-Hilfiker Publisher: ISBN: Category : Languages : en Pages : 178
Book Description
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.
Author: Kliti Grice Publisher: Royal Society of Chemistry ISBN: 1782623051 Category : Science Languages : en Pages : 412
Book Description
The pace of revolution in analytical chemistry in the field of Geosciences has been dramatic over recent decades and includes fundamental developments that have become common place in many related and unrelated disciplines. The analytical tools (nano to macro-scale from stable to radioactive isotopes, compound specific sulfur isotopes) used have been applied to wide-ranging applications from inorganic to organic geochemistry, biodiversity and chronological tools, to build an understanding of how the Earth system evolved to its present state. This book will provide an essential guide to exploring the earth’s natural resources and changing climate by detection science. Individual chapters bring together expertise from across the globe to present a comprehensive outlook on the analytical technologies available to the geoscientist today. Experienced researchers will appreciate the broad treatment of the subject as a valuable reference, while students and those new to the field will quickly gain an appreciation of both the techniques at hand, and the importance of constructing, and analysing, the complex data sets they can generate.
Author: Luigi Mondello Publisher: John Wiley & Sons ISBN: 9780471988694 Category : Science Languages : en Pages : 464
Book Description
Mehrdimensionale Chromatographie im analytischen Labor: Dieses Buch bespricht erstmals alle gängigen Verfahren sowie Anwendungen auf verschiedensten Gebieten, von der Pharmazie, Biologie und Chemie bis hin zur Umwelttechnik und erdölverarbeitender Industrie. Die Autoren sind selbst aktiv in der einschlägigen Forschung tätig.
Author: Christopher Holmes Clark Publisher: ISBN: 9781267729583 Category : Aerosols Languages : en Pages : 249
Book Description
This dissertation introduces and makes use of the Particle-into-Liquid-Sampler coupled to a Time-of-Flight mass spectrometer (PILS-ToF), a new instrumental method used here to provide new chemical characterization information on secondary organic aerosol (SOA). The PILS-ToF instrument improves upon drawbacks found in current state-of-the-art mass spectral chemical characterization methods to include lack of time resolution and ion fragmentation by electron impact ionization in the Aerodyne Aerosol Mass Spectrometer (AMS). The functionality of the PILS-ToF for collection and response to SOA particle formation is validated against a scanning mobility particle sizer (SMPS), a widely accepted and standardized physical chemical characterization instrument, for a well characterized SOA formation experiment, dark ozonolysis of [alpja]-pinene. The PILS-ToF is also used to lend insight into oligomer growth during the NO photo-oxidation of isoprene. It is of atmospheric importance to study SOA formation from isoprene as it is globally the most abundant non-methane hydrocarbon in the ambient. SOA from isoprene is further studied using the PILS-ToF as part of the suite instrumentation at the University of California, Riverside, College of Engineering, Center for Environmental Research and Technology (CE-CERT) atmospheric chamber providing a complete chemical and physical characterization of SOA formed by isoprene with various oxidants under a myriad of oxidant concentration conditions. In addition, the PILS-ToF is used, again in tandem with other chemical and physical characterization methods at CE-CERT, to probe temperature effects on SOA formation from isoprene under many different oxidizing conditions. Finally, the PILS-ToF is used to provide new mechanistic information on SOA formation from trimethylamine and tributylamine, two tertiary amines emitted from anthropogenic and animal husbandry processes. For these two teriary amines the PILS-ToF provides evidence of oligomerization giving a potential explanation to the high SOA yields from these parent compounds.
Author: Henk Kars Publisher: Springer ISBN: 3319331159 Category : Medical Languages : en Pages : 340
Book Description
This introductory volume to a new series on Soil Forensics gives a kaleidoscopic view of a developing forensic expertise. Forensic practitioners and academic researchers demonstrate, by their joint contributions, the extent and complexity of soil forensics. their reports exemplify the broad range of sciences and techniques applied in all stages of forensic soil examinations, from investigations at crime scenes to providing evidence that can be used in court proceedings. Moreover the necessity is depicted of co-operation as a condition for any work in soil forensics between scientists of different disciplines, but no less between scientists and law enforcers.Soils play a role in environmental crimes and liability, as trace evidence in criminal investigations and, when searching for and evaluating, buried human remains. This book shows soil forensics as practiced in this legal context, emerging and solidifying in many countries all over the world, differing in some respects because of differences in legal systems but ultimately sharing common grounds.
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Author: Alexandra Jeanne Boris
Author: Yaping Zhang
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Author: Felipe Daniel Lopez-Hilfiker
Author: Kliti Grice
Author: Luigi Mondello
Author: Christopher Holmes Clark
Author: Henk Kars