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1
Genov, Daniel G. "Conformational analysis of 2-hydroxyalkyl phosphoryl compounds". Thesis, Staffordshire University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306955.
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Davies, Ilona Lynn. "Analysis of polycyclic aromatic compounds by multidimensional chromatography". Thesis, University of Leeds, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328575.
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Madichie, Chinedu Arinze. "The chromatographic analysis of organic compounds in natural waters". Thesis, University of Hull, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310270.
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Silwana, Nothemba. "Structure and thermal stability of selected organic inclusion compounds". Thesis, Cape Peninsula University of Technology, 2012. http://hdl.handle.net/20.500.11838/2618.
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Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2012.Crystal engineering is the synthesis of new crystalline materials with specific chemical and physical properties which allows the comprehensive understanding of the non covalent interactions that occur between molecules in the crystalline state. This has lead to extensive work being done in terms of host design. The study of non-covalent interactions formed by - these materials is crucial to understanding many biological processes. This study focuses on the inclusion compounds of 1, 4-bis (diphenylhydroxymethyl) benzene H, a host compound engineered by EWeber, that conforms to Weber's rules for host design as it is bulky, rigid, and has hydroxyl moieties that act as hydrogen-bonding donors. A Cambridge Structural Database (CSDversion 5.33) search has revealed that no research has been conducted on this host compound. Characterization of the compounds were conducted using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), hot stage microscopy (HS), gas chromatography (GC), powder X-ray diffraction(PXRD) and single X -ray diffraction. Host: guest ratios determined from TG analysis were correlated with structural analysis results. We have successfully prepared inclusion compounds with N, N- dimethylformamide(DMF) N, N- dimethylacetamide (DMA), N-methylformamide (NMF) and N-methylacetamide (NMA), 2-picoline, 3-picoline, 4-picoline, pyridine and morpholine. Following which a series of competition experiments were conducted to establish the selectivity profile of the host by dissolving the host in an excess of two guests pairs, between DMF: DMA, DMF: NMF, DMF: NMA, DMA: NMF, DMA: NMA and NMF: NMA. The results of the competition experiment showed that the host had high selectivity for DMF and the selectivity profile follows a trend as follows DMF>NMA>NMF>DMA. The results for the competition experiments between the picolines, pyridine and morpholine were inconclusive.
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Li, Yunchun. "Characterization of polar organic compounds and source analysis of fine organic aerosols in Hong Kong /". View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202008%20LIY.
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Dixon, John Mark. "The conformational analysis of cyclic compounds by NMR spectroscopy". Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293631.
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Khedhair, K. A. "The conformational analysis of cyclic compounds by spectroscopic methods". Thesis, University of Nottingham, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.353919.
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Ahlgren, Joakim. "Organic Phosphorus Compounds in Aquatic Sediments : Analysis, Abundance and Effects". Doctoral thesis, Uppsala University, Analytical Chemistry, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6701.
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Phosphorus (P) is often the limiting nutrient in lacustrine and brackish eco-systems, and enhanced input of P into an aquatic system might therefore negatively impact the environment. Because modern waste water manage-ment have reduced external P input to surface waters, internal P loading from the sediment has become one of the main P sources to aquatic ecosys-tems, in which relatively unknown organic P compounds seem to be more active in P recycling than previously thought.
This thesis focus is on improving analysis methods for organic P com-pounds in lacustrine and brackish sediments, as well as determining which of these compounds might be degraded, mobilized and subsequently recycled to the water column and on what temporal scale this occur. In both lacustrine and brackish environments, the most labile P compound was pyrophosphate, followed by different phosphate diesters. Phosphate monoesters were the least labile organic P compounds and degraded the slowest with sediment depth. In regulated lakes, it was shown that pyrophosphate and polyphos-phate compound groups were most related to lake trophic status, thus indi-cating their involvement in P cycling. This thesis also indicates faster P turn-over in sediment from the brackish environment compared to sediment from the lacustrine environment.
A comparison of organic P extraction procedures showed that pre-extraction with EDTA, and NaOH as main extractant, was most efficient for total P extraction. Using buffered sodium dithionite (BD) as a pre-extractant and NaOH as main extractant was most efficient for extracting the presuma-bly most labile organic P compound groups, pyrophosphate and polyphos-phate. Furthermore, it was determined that organic P compounds associated with humic substances were more recalcitrant than other P compounds, that the BD step used in traditional P fractionation might extract phosphate monoesters, and that NMR is a statistically valid method for quantification of organic P compounds in sediment extracts.
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Turner, Matthew A. "Boundaries in volatile organic compounds in human breath". Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/20274.
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Exhaled breath is a rich and complex matrix containing many hundreds of compounds. Every breath offers the potential of a non-invasive measurement of the biochemical processes occurring in the human body and it is this notion that has led to the application of breath analysis for the detection of disease. With the majority of research in the field being focused on the detection of biomarkers, little has been presented on how the seemingly homeostatic matrix of breath varies during the course of normal life events. The research in this thesis describes how a subject's emotional state, physical state, and daily activities can alter the composition of exhaled breath.
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Rhydderch, Shona. "Spectroscopic studies of photocatalysts for organic synthesis". Thesis, University of Aberdeen, 2014. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=215112.
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Sidat, Rehana. "The synthesis and analysis of spirobenz-1,3-azoles and related compounds". Thesis, De Montfort University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391342.
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Brien, Kimberly A. "Bismuth aryloxide reactivity kinetics of thermal decomposition and resulting organic oxidation products /". [Fort Worth, Tex.] : Texas Christian University, 2010. http://etd.tcu.edu/etdfiles/available/etd-07232010-131742/unrestricted/Brien.pdf.
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Kumar, Sacheen. "Mass spectrometric analysis of volatile organic compounds in oesophago-gastric cancer". Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/24837.
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In the UK, oesophago-gastric (OG) cancer remains a disease with poor patient outcomes and only 35% of patients are suitable for potentially curative treatment at first presentation. Early detection of these cancers is necessary with Volatile Organic Compound (VOC) analysis being a promising area to explore for new endogenous biomarkers. In this research, the application of Selected-Ion Flow Tube Mass Spectrometry (SIFT-MS), a real-time technique, for the analysis of VOCs in biofluids and exhaled breath has been investigated. The primary aim of this research was to identify potential VOC biomarkers in oesophago-gastric cancer; the long-term application being the translational development of VOCs as non-invasive diagnostic tests. A total of 13 VOCs emitted from gastric content were investigated in the first study; acetone, formaldehyde, acetaldehyde, hexanoic acid, hydrogen sulphide, acetic acid, hydrogen cyanide and methyl phenol were found to be significantly different between oesophago-gastric cancer and healthy groups. In a study on the headspace of urine, acetaldehyde, acetone, acetic acid, hexanoic acid, hydrogen sulphide, methanol and phenol were found to be at significantly different concentrations between oesophago-gastric cancer, positive control and healthy groups. Methodology experiments including the optimisation of VOC sampling techniques with evaluation of exogenous contamination and variability measures have also been conducted. Investigation of reference ranges for C3-C10 aldehydes in healthy subjects using SIFT-MS have been undertaken for the first time; C4-C10 aldehydes were present in the exhaled breath of healthy persons at concentrations < 3 ppbv. In a study on 210 consecutive patients, increased concentrations of fatty acids, phenols and aldehydes were observed in the exhaled breath of patients with oesophageal and gastric adenocarcinoma. The potential effects of clinical confounding factors have been also assessed and possible explanations for the observed differences have been discussed. The results of the pilot study on acute infection demonstrated minimal influence on the cancer-linked VOCs in OG cancer, except for butanal. The analysis of gastric content, urine and exhaled breath have proven that trace compounds are more influential than abundant metabolites in upper gastro-intestinal malignancy. It is also demonstrated that VOC profiles rather than individual compounds are more accurate in the molecular-orientated diagnosis of oesophago-gastric cancer.
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Wang, Yi. "Metal-organic and organic photosensitizers for photocatalytic hydrogen generation and carbon dioxide reduction". HKBU Institutional Repository, 2017. https://repository.hkbu.edu.hk/etd_oa/414.
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This thesis is focused on developing metal-organic and organic molecules for photocatalytic water splitting and carbon dioxide reduction. In chapter 1, an overview of hydrogen production, dye-sensitized solar cells and carbon dioxide reduction are provided. The development history and reaction mechanisms of catalytic systems are introduced along with the typical examples in each field. The applications of both metal-organic and organic compounds are covered. In chapter 2, nine molecular organic photosensitizers were designed and synthesized. The nine molecules were employed as the photosensitizing reagent in the fabrication of dye-sensitized solar cells and applied in photocatalytic water reduction via coupling with TiO2 semiconductors and Pt co-catalyst. The highest turnover number (TON) of 10200 was achieved by organic photosensitizer 1g for hydrogen generation. The effect of alkyl chains and triarylamine donor moiety to the photocatalytic performance was investigated. A shorter alkyl chain was found to favor the reaction due to a lower hydrophobicity which in turn may block the interaction between the photocatalyst and water molecules. Besides, the triarylamine donor units facilitated high hydrogen generation rates by reducing the contact between catalytic active sites and the oxidized form of sacrificial reagents. In chapter 3, five earth-abundant metal complexes were synthesized to serve as the catalyst and CdS nanorods (NRs) were prepared to be the photosensitizer for the photocatalytic water reduction. A cobalt dithiolene complex (2a) achieved a TON of 30635 in 20 h under the blue light irradiation at a concentration of 10 µM. A new complex 2c also gave a high TON of 12375 under the same conditions and its TON was further improved to 115213 in 87 h by reducing the concentration of catalyst by ten times. The size effect of CdS NRs was investigated and larger nanoparticles exhibited higher hydrogen production rates. In chapter 4, ten iridium(III) complexes were synthesized and used as dual-functional molecules in photocatalytic carbon dioxide reduction by acting as both the photosensitizing reagent as well as the catalyst. The best performance was achieved by 3j, giving a TON of 230 under the irradiation of blue LED. A push-pull effect brought by trifluoromethyl and methoxy group sucessfully enhanced the carbon dioxide reduction efficiency. The hydrophobicity of n-butyl chain also provided effective protection to the active sites of reaction intermediate. Additional steric hindrance was found to extend the lifespan of photocatalytic systems but led to a drop in the overall conversion efficiency. Chapter 5 summarizes the specific synthetic procedures and characterization parameters of the molecules in chapters 2-4.
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Bullock, Kerry Robin. "Partitioning of VOCs in aqueous salt solutions". Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/11981.
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ABRAMOWITZ, ROBERT. "ESTIMATION OF THE MELTING POINT OF RIGID ORGANIC COMPOUNDS (COSOLVENT, NAPHTHALENE)". Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183935.
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The melting points of rigid, hydrogen bonding, and non-hydrogen bonding organic compounds have been estimated from their chemical structure. The estimation was accomplished through the use of both additive and non-additive non-constitutive properties of the molecule. The melting points of the aforementioned compounds can be estimated by the equation: TM = TMPN + TIHBN + TPACK + 8.9*EXPAN + 73.1*SIGMAL + 196.3 where the dependent variable, TM, is the melting point of the compound in Kelvin, SIGMAL is the logarithm of the symmetry number for the molecule, EXPAN is the eccentricity of the molecule taken to the third power, TMPN is the summation of the melting point number for each functional group in the molecule, TIHBN is the summation of an intramolecular hydrogen bonding index and TPACK is a packing efficiency index. The solubility of naphthalene in binary, ternary, and quinary cosolvent-water mixtures was determined by HPLC analysis. The samples were equilibrated for 48 hours on a test tube rotator, centrifuged, diluted with acetonitrile, and then injected onto a C8 10 micron column. The cosolvent mixtures used were hydro-organic solutions consisting of water with either methanol, ethanol, isopropanol, acetone, acetonitrile, propylene glycol or a combination of these as the cosolvent. The propylene glycol-water mixtures were allowed to equilibrate for 10 days. In all cases, naphthalene solubilities in binary cosolvent mixtures were found to obey log-linear relationships: log X = SIGMA(FRAC) - log X(w) where X is the mole fraction solubility of naphthalene in the mixture, X(w) is the mole fraction solubility in pure water, FRAC is the volume fraction of the cosolvent, and SIGMA is the slope. SIGMA can be estimated by using the UNIFAC method to predict the solubility in 100% cosolvent and by using the generalized solubility equation of Yalkowsky to estimate the water solubility. These binary equations can then be used to generate ternary and higher multicomponent equations.
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吳祖成 i Zucheng Wu. "Development of acillary techniques for chromatographic analysis of trace organic pollutants in environmental samples". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31236327.
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Han, Dawei. "Atmospheric Hydrocarbon Analysis". PDXScholar, 1993. https://pdxscholar.library.pdx.edu/open_access_etds/4588.
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This treatise studied two correlated important issues in atmospheric chemistry: real-time monitoring of ambient air and removal mechanisms of atmospheric hydrocarbons. An analytical system was designed for the purpose of identification and measurement of sub-ppb level hydrocarbons of different reactivities in air samples. This analytical system was then applied to a series of smog-chamber studies which simulated the removal of reactive hydrocarbons from the atmosphere by reaction with hydroxyl radicals. Six representative atmospheric hydrocarbons ( hexane, octane, toluene, m-xylene, a-xylene and mesitylene) were selected for these experiments. The experimental data indicated that the decay of atmospheric hydrocarbons under laboratory conditions is entirely due to reaction with hydroxyl radicals. The conclusion drawn from a time-resolved plume study that aromatic molecules decay much faster than could be accounted for solely by reaction with hydroxyl radicals was not verified; this indicates a difference between laboratory study and the study in the real atmosphere, and some physical factors besides chemical mechanism might take a more significant role in removing aromatics faster from the atmosphere.
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Hernandez, H. "Analysis of organic compounds by chromatography-mass spectrometry, GC-IR and SFE". Thesis, Swansea University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637268.
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The introductory chapter describes the basics of chromatography and quadrupole mass spectrometry, together with an introduction to polycyclic aromatic hydrocarbons, polychlorinated biphenyls and growth hormones which are the analytes used in later chapters. Chapter two gives an account of packed supercritical chromatography and thermospray interfaces for coupling SFC with mass spectrometry. The separations developed for polycyclic aromatic hydrocarbons and growth hormones are discussed. Limits of detection for ultraviolet-detection for both sets of compounds are determined. In chapters three and four, the extraction by SFE and quantitation by GC/MS of growth hormones in meat is described. Details are given of method development and problems with quantitation. Chapter five is a comparison of GC/MS and GC/FTIR for the identification of isomeric PAHs and PCBs. In addition to the separations, identification of photochemical degradation products and the use of combined library are discussed. The instrumentation used is described in chapter six.
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Huang, Wei [Verfasser], i S. [Akademischer Betreuer] Norra. "Molecular Level Analysis of Atmospheric Organic Compounds / Wei Huang ; Betreuer: S. Norra". Karlsruhe : KIT-Bibliothek, 2019. http://d-nb.info/1192373650/34.
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Smith, Stephen. "The analysis of organic compounds as a tool for diagnosis of disease". Thesis, University of the West of England, Bristol, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444504.
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Abood, Ahmed T. "Source Apportionment Analysis of Measured Volatile Organic Compounds in Corpus Christi, Texas". Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc500059/.
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Corpus Christi among of the largest industrialized coastal urban areas in Texas. The strategic location of the city along the Gulf of Mexico allows for many important industries and an international business to be located. The cluster of industries and businesses in the region contribute to the air pollution from emissions that are harmful to the environment and to the people living in and visiting the area. Volatile organic compounds (VOC) constitute an important class of pollutants measured in the area. The automated gas chromatography (Auto GC) data was collected from Texas Commission of Environmental Quality (TCEQ) and source apportionment analysis was conducted on this data to identify key sources of VOC affecting this study region. EPA PMF 3.0 was employed in this sources apportionment study of measured VOC concentration during 2005 - 2012 in Corpus Christi, Texas. The study identified nine optimal factors (Source) that could explain the concentration of VOC at two urbane monitoring sites in the study region. Natural gas was found to be the largest contributor of VOC in the area, followed by gasoline and vehicular exhaust. Diesel was the third highest contributor with emissions from manufacturing and combustion processes. Refineries gases and evaporative fugitive emissions were other major contributors in the area; Flaring operations, solvents, and petrochemicals also impacted the measured VOC in the urban area. It was noted that he measured VOC concentrations were significantly influenced by the economic downturn in the region and this was highlighted in the annual trends of the apportioned VOC.
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Okunuga, Omolara Oluwaseun. "Analysis of volatile organic compounds produced during the decomposition of human analogues". Thesis, University of Leicester, 2017. http://hdl.handle.net/2381/39915.
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The study of volatile organic compounds (VOCs) associated with decomposing remains is a field of growing interest in forensic science. Over the past decade, there has been an increasing demand to explicate key signatures of decomposition odour in an attempt to improve upon current training kits, aid in the development of an implement which could be used to detect clandestine graves, and to determine the post-mortem interval of a corpse. At present, current research seems to validate the view that the decomposition odour profile is ambiguous because of disparities in the environment in which decomposition occurs, methods of chemical analysis and sample collection techniques. The purpose of this research was to investigate the odour profile surrounding buried and exposed human analogues in controlled environments, in order to understand how VOCs partition between different mediums. To this effect, a bespoke decomposition chamber was developed and characterised in the Real-time Air Fingerprinting Technology laboratory at the University of Leicester, and decomposition VOCs released into the headspace within chamber were monitored online via the use of Chemical Ion Reaction Mass spectrometry (CIR-MS) and Solid Phase Micro Extraction coupled with Gas Chromatography-Mass Spectrometry (SPME-GC-MS). Overall, there was an abundance of polysulphides, specifically dimethyl disulphide detected by both CIR-MS and SPME-GC-MS in the buried and exposed experiments. Seven VOCs argued to be key markers of decomposition in the exposed trials comprised of 2-butanone, dimethyl disulphide, methanethiol, trimethylamine, 1-propanol, 1- butanol, and acetone. In effect, findings from these trials demonstrated that there are distinctive subsets of VOCs released from decomposing carcasses, and soil acts as a sink for majority of these compounds. The use of CIR-MS in the study of decomposition odour was successful, as was the application a novel approach in extracting patterns within the CIR-MS data.
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Huang, Wen-hsin. "Application of comparative molecular field analysis for predicting microbial sulfoxidation /". Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
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Wu, Zucheng. "Development of acillary techniques for chromatographic analysis of trace organic pollutants in environmental samples /". Hong Kong : University of Hong Kong, 1995. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19667188.
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Wood, Erin. "Analysis of high molecular weight organic compounds in ambient aerosols using mass spectrometry". Diss., Connect to online resource, 2005. http://wwwlib.umi.com/cr/colorado/fullcit?p1427784.
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Wilson, Ionara De Lima. "A spatial epidemiological analysis of oral clefts and volatile organic compounds in Texas /". View online, 2007. http://ecommons.txstate.edu/geogtad/13.
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Callear, Samantha. "Preparation, characterisation and structural analysis of salts and co-crystals of organic compounds". Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/66654/.
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In this thesis the factors influencing the formation of a binary compound and the proton transfer within the binary compound have been investigated. The formation of a binary compound, or heteromeric system, over a homomeric system requires the heteromeric system to be more energetically favourable than the homomeric system. In some circumstances, however, no solid crystallises at all. Proton transfer within the binary compound can lead to the formation of a salt, whereas a binary compound containing neutral components is called a co-crystal. The ‘rule of three’ which predicts that proton transfer requires a difference of at least three units between the pKa of the acid and the pKa of the conjugate acid has also been investigated. In particular the relevance of this rule to diprotic acids and bases, and amide groups has been examined. The expression of starting material properties in the binary compounds was also explored. To achieve this an array of diacids and bases have been chosen that consist of α,ω-alkanedicarboxylic acids, α,ω-alkenedicarboxylic acids and tartaric acids with a selection of aliphatic amines, nitrogen-containing heterocycles and imidazole derivatives. The nitrogen-containing heterocycles include some amide functionalities. These compounds have been systematically crystallised together using a liquid-handling robot in a high-throughput manner commonly used in the pharmaceutical industry. The novel structures of 42 salts, 11 co-crystals and 6 mixed co-crystal/salt systems have been prepared and characterised using single crystal X-ray diffraction. Together with the binary compounds already present on the CSD, this has provided the opportunity to assess the impact of various factors on the crystal structures and properties of a total of 61 salts, 11 co-crystals and 8 mixed salt/co-crystal systems. Across the series of α,ω-alkanedicarboxylic acids it has been found that members with an even number of carbons in their alkyl chain (even diacids) form binary compounds more often than those with an odd number of carbons (odd diacids). The diacids with four carbons in their alkyl chains are most likely to form binary compounds. The melting point alternation seen in the α,ω-alkanedicarboxylic acids is also expressed in the binary products. This is particularly prominent with the 2-imidazoldinone-alkanedicarboxylic acid co-crystals, where the supramolecular structure formed by the even diacids is different to that formed by the odd diacids. This has been attributed to the different orientation of the carboxyl groups in the odd diacids. Although the ‘rule of three’ has been found to be applicable to the first ionisation of the diacids, it does not account for the ubiquitous formation of diprotonated bases where the pKa difference is often less than 2 units. Indeed the stoichiometry of the binary compounds was found to often be unpredictable and difficult to rationalise simply. The deprotonation of the diacids appeared to be determined by the optimal hydrogen bonding motifs rather than the pKa. There were also found to be similarities in supramolecular structures within the groups of compounds which could be used to predict the structures of other similar compounds.
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Elemia, Freire Constancia Felise, Simon Edin i Chang Ho Lee. "SPME Method for Chemical Analysis of Heavy Organic Trace Compounds in Synthesis Gas". Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-277054.
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There currently exists no commercialized method for rapid sampling and analysis of trace tar ingas streams. Solid phase microextraction (SPME) with a polydimethylsiloxane (PDMS) solidphase has been previously investigated as a possible candidate due to its solvent-free natureand reusability. This project set out to deliver a proof of concept study to test whether SPMEcan be sufficiently tuned to analyse trace tar content in syngas below the concentration of 0.1mg/Nm 3 . Due to complications that arose from the Covid-19 pandemic, it was unfeasible tocarry out the practical elements of the project. Instead a concept design for carrying out such astudy has been successfully developed. This design envisions a two-chamber setup able tosample syngas directly from a gasifier at 60 °C and 125 °C respectively and is illustrated in thetext. It utilizes commercially available solvent tubes to cross-check and verify the SPME results.I nuläget finns det ingen kommersiell metod för att snabbt extrahera och analysera spår av tjärkomponenteri gasströmmar. Tidigare har solid phase microextraction (SPME) medpolydimetylsiloxan (PDMS) som fast fas undersökts som en möjlig kandidat då den ej kräverlösningsmedel och kan enkelt återanvändas. Detta projekt hade som mål att bevisa att SPMEkan anpassas tillräckligt känsligt för att analysera spår av tjära i syngas med en koncentration påmindre än 0,1 mg/Nm 3 . På grund av komplikationer som uppstod i samband med Covid-19pandemin var det inte möjligt att utföra den praktiska delen av projektet. Istället så har endesign tagits fram för ett koncept som beskriver hur man kan genomföra den praktiska delen.Designen beskriver en två-kammare lösning som kan användas för att ta prover från syngas somkommer direkt från en förgasare. Proverna tas vid temperaturer om 60 °C och 125 °C för attuppnå maximal känslighet. En uppsättning kommersiellt tillgängliga sorbentrör används för attkontrollera resultaten från SPME.
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Ho, Sai Hang. "Analysis of airborne organic compounds using thermal desorption- gas chromatography-mass spectrometry methods /". View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202004%20HO.
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Qi, Ying 1964. "Characterisation of organic and inorganic components in process water from a novel lignite dewatering process". Monash University, School of Chemistry, 2004. http://arrow.monash.edu.au/hdl/1959.1/5234.
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Brücher, Jörg. "The influence of sorption on transport of organic compounds in soil /". Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5481-6.pdf.
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Kasulavada, Santhosh Kumar. "Analysis of Kyrock for Leaching of Impurities in Synthetic Rainwater". TopSCHOLAR®, 2013. http://digitalcommons.wku.edu/theses/1276.
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Kyrock is a coarse grained sandstone with a complex mixture of organic and inorganic compounds. Mining of Kyrock is for use in road construction and roofing. Kyrock samples were analyzed using scanning electron microscopy to obtain elemental analysis. High levels of carbon indicate the presence of organic compounds. Analysis of an acid digestion of the samples using inductively coupled plasma spectroscopy showed inorganic compounds such as titanium oxide, vanadium oxide along with traces of arsenic. Elemental analysis of samples indicates a percent of carbon, and sulfur with no notable traces of nitrogen. Pyrolysis of the samples was done using gas chromatography mass spectroscopy with a gradual increase in temperature to 160o C resulted in the release of inorganic and organic compounds. Synthetic rainwater was prepared to examine the leaching of compounds and the leachate was analyzed using liquid chromatography mass spectroscopy and gas chromatography mass spectroscopy.
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Brown, S. M. "The chemistry and conformational analysis of some normal and medium ring alicyclic and heterocyclic compounds". Thesis, University of Huddersfield, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354322.
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Vitzthum, von Eckstaedt Christiane D. "δ13C and δD measurements of volatile organic compounds in a variety of emissions by thermal desorption compound specific isotope analysis". Thesis, Curtin University, 2011. http://hdl.handle.net/20.500.11937/851.
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Volatile organic compounds (VOCs) can be related to different compound classes but they all have a distinct vapour pressure allowing them to enter the atmosphere under ambient conditions. VOCs can undergo various reactions in the atmosphere and are emitted by various processes (anthropogenic and natural). Compound specific isotope analysis (CSIA) has been used in many other research studies to track the fate and source of compounds in the environment and the geological record. The majority of CSIA has been applied to extracts from soil, sediment or crude oils requiring entirely different sampling techniques compared to atmospheric samples. Applying CSIA to atmospheric compounds is a growing research field but has mainly being restricted to stable isotopes of carbon.This PhD thesis presents a novel application for adsorptive sampling on TenaxTA to analyse compound specific δ13C and δD of a range of atmospheric VOCs (C6 - C10). For the first time a 2-stage thermal desorption (TD) unit was linked to gas chromatography isotope ratio mass spectrometry (GC-irMS) and instrumental conditions were thoroughly investigated and optimised. Results obtained by using a standard mix of eleven VOCs confirmed reliability of TD-GCirMS analyses with standard deviations (SD) below instrument precision. δ values showed negligible isotopic fractionation compared to results obtained from traditional GC-irMS analysis (without TD unit) demonstrating the suitability of TD for CSIA.The technique was applied to analyse VOCs from various emission sources, e.g. car exhaust, biomass combustion and an industry stack. The results obtained have provided some insight into the formation processes of the VOCs investigated. δ13C values from an alumina refinery emission support a natural origin for the VOCs (organic material in bauxite ore). The δD values (21 to - 137 ‰) of the industry emission were consistently more enriched in D compared to δD values of VOCs previously reported making the δ values of VOCs in the industrial stack unique. Car exhaust emission from a petrol engine showed significant differences in δ values for VOCs up to 2 ‰ and 25 ‰ (δ13C and δD, respectively) at different tank fuel levels when using the same fuel batch. Car exhaust emission samples from a diesel engine showed a high content of highly complex mixture of unresolved compounds thus chromatographic baseline separation of VOCs was not achieved for stable hydrogen isotope analysis and led to unreliable δ values. The results from different biomass combustion emissions (including 5 species of C3 plants and 3 species of C4 plants) confirmed significant differences in δ13C of VOCs between C3 and C4 plants due to their specific metabolic pathways for carbon fixation in photosynthesis. The δD of VOCs derived from dicotyledons were less depleted in D compared to δD of VOCs derived from grasses (differences >27 ‰) indicating that the VOCs are derived mainly from lignin/cellulose rather than from lipids since dicotyledons contain higher amounts of lignin/cellulose.Due to the unique isotopic signatures of the VOCs from the different emission sources it was possible to distinguish their origins. Furthermore, TD-GC-irMS shows great potential to establish other emission sources in the environment and may help to gain some insight into their modes of formation.
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Theberge, Ashleigh Brooks. "Droplet-based microfluidics for chemical synthesis and integrated analysis". Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609687.
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Sauvage, Carina [Verfasser]. "Analysis of Non-Methane Hydrocarbons and Organic Nitrogen Compounds in the Atmosphere / Carina Sauvage". Mainz : Universitätsbibliothek Mainz, 2019. http://d-nb.info/118994247X/34.
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Ruotsalainen, Daniel. "Analysis of organic compounds in the rhizosphere soil of Cyperus rotundus using LC-MS". Thesis, KTH, Kemi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-291534.
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Den presenterade studien hade som syfte att utveckla en extraktions-, provpreparerings- och analysmetod för jorden, i vilken gräset Cyperus rotundus växer, i ett försök att identifiera möjliga äggläggningsattraherande ämnen för myggan Anopheles gambiae. Högupplösande vätskekromatografi med hydrofob stationär fas (RP-HPLC, en.) med Masspektrometri med Elektrosprejjonisering (ESI-MS, en.) användes för separation och detektion av de extraherade proverna. Ett flertal extraktionssatser gjordes, där parametrar och tekniker ändrades under utvecklingen av arbetet. Ultraljudsassisterad extraktion (UAE) av jord i en 50:50 (v/v) blandning av metanol och vatten visades vara mest effektiv av de undersökta metoderna. Upprening av jordextraktioner med fastfasextraktion (SPE, en.) visades ha en positiv inverkan på signalintensiteten i kromatogrammen såväl som att reducera intensiteten av de systemtoppar som eluerar vid dödtiden. Detta indikerar att de poläraste ämnena har renats bort. En jämförelse gjordes mellan en extraktion av jord som legat i blöt i fem dagar och jord som extraherats utan att blötläggas. En skillnad kunde ses och visades genom att jämföra kromatogram och masspektra från de två proverna. Tandem-MS-experiment gjordes för ett flertal prekursorjoner med avsikt att identifiera ämnena genom jämförelse med databaserna Human Metabolome Database (HMDB), Metlin och Massbank, men inga överrensstämmande jämförelser kunde göras. Tandem-MS-resultaten användes även för att jämföra efter varandra följande kromatografiska toppar med liknande MS1-spektrum. En identifieringsmetod bör utvecklas innan metoden som presenterats i detta arbete valideras och vidareutvecklas.The present study aimed to develop an extraction, sample preparation and analysis method for the rhizosphere soil of the grass Cyperus rotundus in an attempt to identify possible oviposition attractants of the Anopheles gambiae mosquito. Reversed Phase High Performance Liquid Chromatography (RP-HPLC) coupled online with Electrospray Ionization Mass spectrometry (ESI-MS) was used for the separation and detection of the extracted samples. Multiple extraction batches were done, altering parameters and techniques along the way. Ultrasound-Assisted Extraction (UAE) of the soil with a 50:50 (v/v) mixture of methanol and water was determined to be the most effective of the attempted methods. Purifying soil extracts with Solid Phase Extraction (SPE) showed to have an impact on the signal intensities in the chromatogram as well as reducing the intensity of system peaks eluting at the dead-time. This indicates that more polar compounds were removed during the SPE purification. A comparison was done between an extraction of soil soaked in water for five days and soil extracted without prior wetting. A difference could be seen and was shown by comparing chromatograms and mass spectra from the two samples. Tandem MS experiments were done for multiple precursor ions in order to identify the compounds by comparison in databases Human Metabolome Database (HMDB), Metlin and Massbank, but no matches in the databases were found. The tandem MS results were also used for comparison of consecutive chromatographic peaks with similar MS1-spectra. An identification method should be developed before the method presented in this work is validated and optimized further.
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Xie, Xiaofeng. "High Flow Air Sampler for Rapid Analysis of Volatile and Semi-Volatile Organic Compounds". BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/6165.
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Volatile and semi-volatile organic compounds are ubiquitous, and some of them are hazardous. The ability to rapidly detect and identify trace levels of them in air has become increasingly important. The conventional device used today for sampling and concentrating them in air is thermal desorption tubes filled with specific sorbents, which can only collect air samples at flow rates of 100-200 mL/min. In order to detect low concentration (ppt level) VOC compounds, long sampling time (>2 h) and sensitive detection are required. At the same time, portable instrumentation for on-site analysis has been developing rapidly. The somewhat lower performance of portable instruments compared to benchtop systems requires the sampling of even greater sample volume in order to reach the same detection limits. In this study, two high flow rate air sampling devices, i.e., a multi-capillary trap and a concentric packed trap, were developed to sample a large volume of air in a short time period. The multi-capillary trap was constructed by bundling analytical capillary gas chromatography columns together in parallel. As low as single digit ppt detection limits were reached in less than 25 min with this trap, and as high as 8.0 L/min flow rate was sampled. The simple and compact multi-capillary trap could be easily used with a conventional thermal desorption system to perform high flow rate sampling. A concentric packed high flow rate trap was also developed by packing sorbent layers concentrically around an empty tube. The concentric packed trap achieved a high flow rate (>10 L/min) because it had a high surface area and short sorbent bed. Also, its large sorbent amount (>1 g) provided large breakthrough volume (>100 L) required to achieve low detection limits. An equilibrium distribution sampling system was developed by absorbing selected analytes in granular PDMS to provide calibration for on-site instrumentation. Furthermore, a needle trap device was coupled in tandem to both high flow rate air samplers to perform second-stage concentration of VOCs down to the ppt level. Concentration factors of 104 to 105 were achieved within 30 min using both systems, i.e., over 10 to 100 times more sample was collected compared to conventional TD systems.
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McBrayer, Tinker R. "Anaerobic biodegradation of selected organic compounds with and without inhibition of sulfate reducing bacteria". Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/46047.
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The primary objective of this study was to investigate the use of hydrogen as a structural substitute or as a reducing equivalent in the anaerobic biodegradation of methanol, methyl tert-butyl ether (MTBE), toluene, phenol, and 2,4- dichlorophenol. In addition, biodegradation rates of these compounds at various initial concentrations with and without inhibition of sulfate reducing bacteria were determined along with anaerobic biodegradation rate constants for each of the compounds studied.
Rates of methanol biodegradation were only slightly altered in molybdate amended microcosms indicating that methanol is a noncompetitive substrate in Blacksburg soil. MTBE biodegradation was slow and followed first order kinetics with respect to initial concentration. Molybdate had no affect on MTBE biodegradation alone, but increased the biodegradation rate in MTBE microcosms which were amended with ethanol. Toluene, phenol, and 2,4-dichlorophenol biodegradation proceeded at two different rate versus initial concentration relationships for lower and upper concentration ranges. Phenol biodegradation followed first order kinetics. The 2,4-dichlorophenol biodegradation rate order varied from 0.78 to 1.75. Monod kinetics were followed by methanol, toluene, and phenol, but not by MTBE, ethanol amended MTBE, or 2,4-dichlorophenol.
Addition of molybdate to inhibit sulfate reduction increased the degradation rates more for compounds which may require hydrogen in a structural position (2,4-dichlorophenol, MTBE) than those which require hydrogen for proton reduction (methanol). Biodegradation or recalcitrant compounds may be stimulated by the addition of organics (such as ethanol) which produce hydrogen upon biodegradation.
Master of Science
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Gasper, Susan M. "Spin selective reactivity of arylcations ; Part II: Anthraquinone oligonucleotide conjugates as probes of electron transfer in DNA". Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/30533.
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Roghani, Mohammadyousef. "INVESTIGATION OF VOLATILE ORGANIC COMPOUNDS (VOCs) DETECTED AT VAPOR INTRUSION SITES". UKnowledge, 2018. https://uknowledge.uky.edu/ce_etds/73.
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This dissertation investigates unexplained vapor intrusion field data sets that have been observed at hazardous waste sites, including: 1) non-linear soil gas concentration trends between the VOC source (i.e. contaminated groundwater plume) and the ground surface; and, 2) alternative pathways that serve as entry points for vapors to infiltrate into buildings and serve to increase VOC exposure risks as compared to the classic vapor intrusion model, which primarily considered foundation cracks as the route for vapor entry. The overall hypothesis of this research is that theoretical knowledge of fate and transport processes can be systematically applied to vapor intrusion field data using a multiple lines of evidence approach to improve the science-based understanding of how and when vapor intrusion exposure risks will pose increased exposure risk; and, ultimately this knowledge can be used to develop policies that reduce exposure risks. The first objective of this research involved numerical modeling, field sampling and laboratory tests to investigate which factors influence soil gas transport within the subsurface. Combining results of all of these studies provide improved understanding of which factors influence VOC fate and transport within the subsurface. Importantly, the results demonstrate a non-linear trend between the VOC source concentration in the subsurface and the ground surface concentration at the study site, which disagrees with many vapor intrusion conceptual models. Ultimately, the source concentration may not be a good predictor of shallow soil gas concentrations. Laboratory tests described the effect of soil characteristics such as the soil water content on VOC vapor diffusion. The numerical model was able to explain specific conditions that could not be described by the field and laboratory data alone. A paper was published that summarizes the major outcomes from this objective (Pennell et al, 2016). The second objective of this research investigated preferential pathways for VOC vapor migration into buildings. Sewer systems can act as important pathways for vapor intrusion. The research objective is to evaluate conditions that increase the potential for inhalation exposure risks via vapor intrusion thorough sewer systems into indoor spaces. A field study was conducted in California over a 4-year period to investigate the spatial and temporal variability of alternative pathways (e.g. aging infrastructure piping systems) within the context of vapor intrusion exposure risks. A paper was published that summarizes the major outcomes from the field study (Roghani et al. 2018). The final research objective involved the development of a numerical model to describe VOC fate and transport within a sewer system. The numerical model predicts VOC mass transport. The model results were compared to the field data and provides insight about the role preferential pathways play in increasing VOC exposure risks.
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Wu, Hao. "Metal-organic compounds of iridium(III) and platinum(II): synthesis, characterization and optoelectronic applications". HKBU Institutional Repository, 2014. https://repository.hkbu.edu.hk/etd_oa/61.
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The molecular design, synthesis and characterization of a series of ligands and the corresponding novel iridium(III) or platinum(II) complexes are discussed in this thesis. Their photophysical and electrochemical properties, the applications in organic light-emitting diodes (OLEDs), dye-sensitized solar cells (DSSCs), aggregation induced emission (AIE) and time-resolved infrared (TRIR) study are also investigated. Chapter 1 generates a brief overview of the background, principle, and development of OLEDs, DSSCs, AIE materials and the involvement of the TRIR technique. Chapter 2 describes the synthesis, spectroscopic, photophysical and electrochemical characterization of a series of cationic iridium(III) complexes. Strong electron-withdrawing carboxylic acid substituted bipyridyl was involved in the ligand system and the intra-ligand charge transfer character of diphenylamino containing ligand further shift the dominant absorption band to the lower energy region. Some of them were applied for DSSC device fabrication. Chapter 3 presents the synthesis, spectroscopic, photophysical and electrochemical characterization as well as OLED application of a group of cyclometalated iridium(III) complexes by using 2-substituted 9-benzylcarbazolyl, 9-phenylcarbazolyl or 2-methyl-7-phenylcarbazolyl groups as the ligands. They show significant bathochromatic shift from those using 3-substituted ligands. And this can be explained by the fact that more electron density is located at 2-position of carbazole moiety and make them suitable candidates for deep red OLED application. Chapter 4 delivers the synthesis, spectroscopic, photophysical and electrochemical characterization of a series of platinum(II) acetylide complexes for AIE study. All of the complexes contain [4-(1,2,2-triphenylethenyl)phenyl]ethynyl ligand, which is designed from AIE active building block tetraphenylamine (TPE). Some of these metal complexes show AIE behavior. Chapter 5 outlines the synthetic methodology and characterization of another series of cyclometalated iridium(III) and platinum(II) complexes, containing TPE or carbazole units. It is very interesting to find out that there is hardly any emission in all of the TPE-containing cyclometalated complexes, nor any signs of AIE behavior. Meanwhile, for carbazole-containing platinum(II) complexes, remarable AIE results could be generated, which is believed to be important for further organometallic AIE active material development. Chapter 6 describes the synthetic methodology and characterization of a series of symmetric or asymmetric platinum(II) acetylides. Some of them were further applied for TRIR analysis to generate detailed experimental information of the electron transitions during excitation. The results demonstrate that both localized and delocalized metal ligand orbital mixing could be generated according to the variations in electronegativity of the ligand system. Chapter 7 and 8 present the concluding remarks and summarize the experimental details of all of the previous chapters.
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MOREIRA, RENATA. "Estudo da pirólise lenta da casca da castanha de caju". reponame:Repositório Institucional do IPEN, 2015. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26078.
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Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-04-08T12:32:34Z
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Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Mörbt, Nora. "Differential proteome analysis of human lung epithelial cells following exposure to aromatic volatile organic compounds". Phd thesis, Universität Potsdam, 2010. http://opus.kobv.de/ubp/volltexte/2010/4925/.
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The widespread usage of products containing volatile organic compounds (VOC) has lead to a general human exposure to these chemicals in work places or homes being suspected to contribute to the growing incidence of environmental diseases. Since the causal molecular mechanisms for the development of these disorders are not completely understood, the overall objective of this thesis was to investigate VOC-mediated molecular effects on human lung cells in vitro at VOC concentrations comparable to exposure scenarios below current occupational limits.
Although differential expression of single proteins in response to VOCs has been reported, effects on complex protein networks (proteome) have not been investigated. However, this information is indispensable when trying to ascertain a mechanism for VOC action on the cellular level and establishing preventive strategies.
For this study, the alveolar epithelial cell line A549 has been used. This cell line, cultured in a two-phase (air/liquid) model allows the most direct exposure and had been successfully applied for the analysis of inflammatory effects in response to VOCs. Mass spectrometric identification of 266 protein spots provided the first proteomic map of A549 cell line to this extent that may foster future work with this frequently used cellular model. The distribution of three typical air contaminants, monochlorobenzene (CB), styrene and 1,2 dichlorobenzene (1,2-DCB), between gas and liquid phase of the exposure model has been analyzed by gas chromatography. The obtained VOC partitioning was in agreement with available literature data.
Subsequently the adapted in vitro system has been successfully employed to characterize the effects of the aromatic compound styrene on the proteome of A549 cells (Chapter 4). Initially, the cell toxicity has been assessed in order to ensure that most of the concentrations used in the following proteomic approach were not cytotoxic. Significant changes in abundance and phosphorylation in the total soluble protein fraction of A549 cells have been detected following styrene exposure. All proteins have been identified using mass spectrometry and the main cellular functions have been assigned. Validation experiments on protein and transcript level confirmed the results of the 2-DE experiments. From the results, two main cellular pathways have been identified that were induced by styrene: the cellular oxidative stress response combined with moderate pro-apoptotic signaling. Measurement of cellular reactive oxygen species (ROS) as well as the styrene-mediated induction of oxidative stress marker proteins confirmed the hypothesis of oxidative stress as the main molecular response mechanism. Finally, adducts of cellular proteins with the reactive styrene metabolite styrene 7,8 oxide (SO) have been identified. Especially the SO-adducts observed at both the reactive centers of thioredoxin reductase 1, which is a key element in the control of the cellular redox state, may be involved in styrene-induced ROS formation and apoptosis.
A similar proteomic approach has been carried out with the halobenzenes CB and 1,2-DCB (Chapter 5). In accordance with previous findings, cell toxicity assessment showed enhanced toxicity compared to the one caused by styrene. Significant changes in abundance and phosphorylation of total soluble proteins of A549 cells have been detected following exposure to subtoxic concentrations of CB and 1,2-DCB. All proteins have been identified using mass spectrometry and the main cellular functions have been assigned. As for the styrene experiment, the results indicated two main pathways to be affected in the presence of chlorinated benzenes, cell death signaling and oxidative stress response. The strong induction of pro-apoptotic signaling has been confirmed for both treatments by detection of the cleavage of caspase 3. Likewise, the induction of redox-sensitive protein species could be correlated to an increased cellular level of ROS observed following CB treatment.
Finally, common mechanisms in the cellular response to aromatic VOCs have been investigated (Chapter 6). A similar number (4.6-6.9%) of all quantified protein spots showed differential expression (p<0.05) following cell exposure to styrene, CB or 1,2-DCB. However, not more than three protein spots showed significant regulation in the same direction for all three volatile compounds: voltage-dependent anion-selective channel protein 2, peroxiredoxin 1 and elongation factor 2. However, all of these proteins are important molecular targets in stress- and cell death-related signaling pathways.Die vermehrte Verwendung von Produkten, welche flüchtige organische Substanzen (VOC - volatile organic compound) enthalten, hat eine generelle Exposition der Bevölkerung mit diesen Substanzen an Arbeitsplätzen aber auch in Wohnräumen bedingt. VOCs stehen im Verdacht, zur zunehmenden Inzidenz umweltbedingter Erkrankungen beizutragen. Da die molekularen Ursachen dieser Erkrankungen bisher noch unverstanden sind, war es ein übergeordnetes Ziel dieser Arbeit, VOC-vermittelte molekulare Effekte in menschlichen Lungenepithelzellen anhand eines in vitro Modells zu untersuchen. Dabei sollten vor allem Konzentrationen unterhalb der gültigen Arbeitsplatzgrenzwerte untersucht werden. Obwohl Effekte auf einzelne Proteine bekannt sind, wurden bisher keine Effekte der VOC-Exposition auf das komplexe Netzwerk der zellulären Proteine (Proteom) untersucht. Dieses Wissen ist essentiell, um induzierte zelluläre Mechanismen zu verstehen und Strategien zu deren Vermeidung zu entwickeln. Für die hier durchgeführten Untersuchungen wurde die Lungenepithelzelllinie A549 in einem Zweiphasenexpositionsmodell eingesetzt. Dieses ermöglichte eine möglichst direkte zelluläre Exposition und wurde bereits erfolgreich verwendet, um durch VOC hervorgerufene Entzündungseffekte zu identifizieren. Die massen-spektrometrische Identifikation von 266 Proteinflecken lieferte die erste umfassende Proteomkarte der A549 Zelllinie, welche nachfolgende Untersuchungen mit diesem häufig verwendeten Zelltyp erleichtern wird. Zusätzlich wurde die Verteilung der drei gängigen Luftkontaminanten Chlorbenzol (CB), Styrol and 1,2-Dichlorobenzol (1,2-DCB) zwischen den beiden Phasen (gas/flüssig) des Expositionsmodells gaschromatographisch bestimmt. Die Verteilung entsprach den verfügbaren Literaturdaten. Anschließend wurde das modifizierte Expositionsmodell erfolgreich eingesetzt, um styrol-vermittelte Effekte auf das Proteom der A549 Zellen zu charakterisieren (Kapitel 4). Zu Beginn erfolgte die Erfassung der Zelltoxizität der Substanz, um sicher zu stellen, daß der überwiegende Teil der späteren Expositionsexperimente mit subtoxischen Konzentrationen durchgeführt wird. Es konnte eine signifikant veränderte Expression und Phosphorylierung der löslichen Proteinfraktion der A549 Zellen als Reaktion auf die Styrolexposition festgestellt werden. Die regulierten Proteine wurden massenspektrometrisch identifiziert und ihre wichtigsten Funktionen wurden zugewiesen. Validierungsexperimente auf Protein- und auf Transkriptebene bestätigten die 2-DE Ergebnisse. Insgesamt konnte die zelluläre Reaktion durch die styrol-vermittelte Induktion zweier zentraler Mechanismen erklärt werden: oxidativer zellulärer Stress und beginnende Apoptose. Folgeexperimente wie die Messung der Menge der zellulären reaktiven Sauerstoffspezies (ROS) und die Induktion von redox-sensitiven Markerproteinen konnte die Hypothese eines styrol-induzierten oxidativen Milieus bestätigen. Schließlich wurden Proteinaddukte des reaktiven Styrolmetaboliten Styrol 7,8 epoxide (SO) identifiziert. Besonders die SO-Addukte, welche and den beiden aktiven Zentren der Thioredoxin Reduktase 1 gefunden wurden könnten eine wichtige Rolle bei der styrol-induzierten ROS-Bildung sowie der beginnenden Apoptose spielen. In Analogie zum Styrolexperiment wurden die Effekte der halogenierten Benzole CB und 1,2-DCB untersucht (Kapitel 5). Es konnten ebenfalls sämtliche Proteine identifiziert und die wichtigsten zellulären Funktionen zugewiesen werden. Diese Substanzen modulierten ebenfalls apoptotische Signalwege und die zelluläre Antwort auf oxidativen Streß. Der beobachtete starke pro-apoptotische Effekt konnte für beide Substanzen mit der Spaltung der Caspase 3 nachgewiesen werden. Weiterhin konnte für CB die Induktion redox-sensitiver Proteinspezies mit einem beobachteten höherem Gehalt an ROS erklärt werden. Schließlich wurden ähnliche Mechanismen der zellulären Antwort auf die Exposition mit den drei untersuchten aromatischen VOCs diskutiert (Kapitel 6). Alle getesteten VOCs verursachten eine vergleichbare differentielle Expression (p<0,05) von 4,6-6,9% aller quantifizierten Proteinspezies. Nur drei Proteinspots wurden dabei gemeinsam für alle VOCs reguliert: voltage-dependent anion-selective channel protein 2, peroxiredoxin 1 and elongation factor 2. Allerdings gehören diese drei Proteine zu wichtigen zellulären Zielstrukturen der Signalwege für Stressantwort und Zelltod.
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Sit, Hoi Leung. "Applications of thermal desorption GCMS analysis of nonpolar organic compounds in source and ambient aerosols /". View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202008%20SIT.
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Kongtip, Pornpimol. "Charcoal cloth as an adsorbant for the analysis of volatile organic compounds in indoor air". Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41640.
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A comparison was made between NIOSH-type, prepacked nutshell charcoal tubes and layers of commercial charcoal cloth in a stainless steel cassette designed for the active sampling/adsorption of different concentrations of a mixture of volatile organic chemicals (VOCs) (benzene, trichloroethylene, toluene, tetrachloroethylene, chlorobenzene and o-xylene). Physicochemical parameters of the charcoal cloth including breakthrough times and volumes and adsorption capacities were determined for toluene and the VOC mixture. The quantitative removal of VOCs from the charcoal cloth by solvent desorption, by supercritical fluid extraction (SFE), and by thermal desorption was studied prior to analysis by gas liquid chromatography with photoionization detection. Optimal conditions were explored both in laboratory and industrial environments.Charcoal cloth was comparable to the NIOSH tube, adsorbed VOCs being quantitatively removed at any time up to 32 days after sampling. Although solvent (pentane, hexane) desorption yielded accurate, reproducible results with a high percent recovery of the VOCs, a major disadvantage was the irreparable damage done to the cloth, preventing its repeated use. Desorption by SFE proved unreliable for these low molecular weight VOCs, both the collecting solvents and the VOCs being lost during extraction. Thermal desorption proved to be efficient, sensitive and reliable, repeated heating having no effect on the adsorptive properties of the cloth. Charcoal cloth would appear to be a useful adsorbing medium for air sampling of both industrial and office building/home environments for either single chemicals or mixtures.
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Ketsise, Marina Nkhalong. "Monitoring and analysis of semi-volatile organic compounds in ambient air / by Marina Nkhalong Ketsise". Thesis, North-West University, 2006. http://hdl.handle.net/10394/1143.
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The growing concern for environmental pollution indicates the importance of
correctly predicting the fate of pollutants in ambient air. This study was
conducted to predict the ambient levels of polycyclic aromatic hydrocarbons
(PAH's) in the greater Sasolburg area and to better understand the
distribution and the sources of PAH's in ambient air. PAH's are chemical
compounds which consist of two or more fused benzene rings and made
entirely from carbon and hydrogen. PAH's are widespread environmental
pollutants which are mainly emitted from combustion sources, which includes
automobiles, industrial processes and domestic heating systems. As a result
of the ubiquitous presence of these combustion sources, PAH's are
distributed throughout the atmosphere in both the gas and particulate phases.
There is an international concern about human exposure to a number of
PAH's, mainly benzo[a]pyrene and their associated health effects
(carcinogenic and mutagenic). Human exposure to PAH's may occur via
food, water, air and direct contact with materials containing PAH's.
In the case of PAH's, monitoring is difficult as these species have a very low
ambient concentration. Advanced sampling techniques are necessary to
collect adequate volumes of air samples. A high volume sampler equipped
with polyurethane foam (PUF) and quartz filters were used to collect the air
samples in the greater Sasolburg area. The polyurethane is used to collect
gas-phase samples while the filter is used to collect the particle-phase
samples.
Ambient air quality measurements for PAH's were conducted during the
period of November to December 2005 at two sites in Sasolburg region
(industrial and hospital area). Sixteen PAH species were targeted for this
study and of the sixteen species; seven of them were identified as priority
PAH's by US EPA; on basis of concern that they might cause cancer in
animals and humans.
The measured results obtained showed anthracene to be one of the most
predominant PAH species obtained in both the gas and particle phase. The
total PAH emissions produced in the Sasolburg area were determined by
using emission factors from the United State Environmental Protection
Agency [39] for residential area and the emission factors from Environmental
Protection Agency 42 [52] were used to determine the total emission
produced for the industrial area.
The measured results were modelled using an Atmospheric Dispersion
Modelling System developed by Cambridge Environmental Research
Consultants to predict the ambient levels of PAH's. The results showed
naphthalene, phenanthrene and fluoranthene to be the dominant PAH species
at the industrial area. The accuracy of the model predicted concentrations
performed best for the following PAH species: fluorene; fluoranthene and
pyrene at both the Sasolburg hospital and industrial receptors. Conversely
the accuracy of the model predicted concentrations consistently performed
worst for the following PAH species: acenaphthene; acenaphthylene;
naphthalene and phenanthrene at both the Sasolburg hospital and industrial
receptors. The model predicted that the concentrations were significant
overestimates of the actual measured concentrations, resulting in huge model
deviations.
From the results obtained in this study, it is deduced that most of the PAH's
were obtained in the gas-phase than in the particle phase. The highest PAH
concentration in particle-phase was obtained at Sasolburg industrial area
while the highest PAH concentration in gas-phase was observed at Sasolburg
hospital areaThesis (M.Sc. (Chemistry))--North-West University, Potchefstroom Campus, 2007.
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Patel, Mitesh Kantilal. "Analysis of volatile organic compounds in breath as a potential diagnostic modality in disease monitoring". Thesis, Cranfield University, 2011. http://dspace.lib.cranfield.ac.uk/handle/1826/7861.
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The use of breath odours in medical diagnosis dates back to classical times, though in its modern form the technique is only a few decades old. There are several breath tests in common clinical use, though all of them involve administration of a known or labelled exogenous compound. More recently, over the last twenty years, interest has focussed on analysis of endogenous metabolites in breath, but despite a large number of published studies reporting a number of disease markers, there has been little or no impact on clinical practice. Nonetheless, breath analysis offers a number of potential advantages over current biochemical methods. One major advantage of breath analysis is its non-invasive nature, which has led to significant interest in its use at point-of care for monitoring chronic diseases such as diabetes and the chronic infections ubiquitous in cystic fibrosis. However, breath analysis classically involves the use of expensive laboratory based analytical equipment which requires extensively-trained personnel and which cannot readily be miniaturised. Systems based on simple gas sensors might offer a way of overcoming these limitations. In recent years, Cranfield University has developed an instrument called the single metal oxide sensor gas analyser (SMOS-GA, more commonly referred to as the “Breathotron”) as a proof of concept for sensor-based breath analysis. In this project the Breathotron has been used in conjunction with selected ion flow tube mass spectrometry (SIFT-MS) and thermal desorption gas chromatography mass spectrometry (TD-GC-MS) to determine the changes in the concentrations of volatile organic compounds (VOCs) in breath in a number of experimental situations which a relevant to the diagnostic monitoring of diabetes mellitus. Studies conducted on clinically healthy volunteers were: an oral glucose tolerance test (OGTT); a six minute treadmill walking test; and a bicycle ergometer test. Additionally Breathotron and analytical data were also obtained during a hypoglycaemic clamp study carried out on hypoglycaemia-unaware Type I diabetics. The principle breath volatiles determined analytically were: acetone, acetaldehyde, ammonia isoprene though data on a number of others was also available. In general, it proved difficult to establish any reproducible relationship between the concentration of any compound measured and blood glucose concentration any of the experimental interventions. It was notable, though, that statistically significant associations were observed occasionally in data from individual volunteers, but even these were not reproduced in those trials which involved repeated measurements. This remained true even where spirometry data were used to derive VOC clearance rates. This may explain previous reports from smaller studies of an association between glucose and breath acetone concentration. It seems probable that any experimentally-induced changes in breath VOC concentration or clearance were of much smaller magnitude than background variability and was consequently not detectable. These observations were mirrored in the sensor-derived results. Multivariate analysis across all trials where Breathotron data were obtained suggested clustering by individual volunteer rather than glycaemic status. This suggests that that there exists a “background” breath volatile composition, dependent perhaps on such factors as long-term diet, which is independent of our experimental intervention. The Breathotron was also used as a platform to assess the performance of three different types of mixed metal oxide sensor in vitro. Calibration curves were generated for acetone, ammonia and propanol covering the physiological range of concentrations and with a similar water content to breath. Close correlations were obtained between concentration and the amplitude of the sensor response. Sensor response reproducibility was also determined using acetone at a concentration of 10ppm with dry and humidified test gas. There were significant differences between sensor types in overall reproducibility and in response to humidity. These results suggest that had there been substantial changes in breath VOC composition as a result of our experimental interventions, any of the types of sensor used would have been capable of responding to them. In summary, these results do not support the efficacy of breath VOC analysis as a means of non-invasive diagnostic monitoring.
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Hassett, Anthony John. "Analysis of volatile organic compounds in water by sorptive extraction and gas chromatography - mass spectrometry". Diss., University of Pretoria, 2001. http://hdl.handle.net/2263/26860.
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