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1
Olivier, EI, Toit D. Du, and JH Hamman. "Development of an analytical method for the evaluation of N,N-dimethylformamide in dosage form design." Pharmazie, 2007. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000865.
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N,N-Dimethylformamide (DMF) is a well-known chemical entity that is extensively used for pharmaceutical,
biomedical and chemical applications. Previous research identified the need for the development
of an effective dosage form for the systemic delivery of DMF due to its unique antiviral properties. For
purposes of quality control and evaluation during pharmaceutical product development, development
of an analytical method was required. A gas chromatographic (GC) method was developed with a
flame-ionization detector (FID) on a carbowax packed glass column. 2-Methoxyethanol was used as
internal standard. The analytical method proved to be capable of separating DMF and 2-methoxyethanol
adequately within a relatively short runtime of 2.5 min. The analytical method described was primarily
developed for use in dissolution studies of DMF containing delivery systems. Various physicochemical
properties of candidate internal standard materials were correlated with the observed retention
times of these compounds. The best correlation (r2 ¼ 0.8077) was obtained between the boiling
point and the retention time of the compounds for the current application. The boiling point of an
internal standard candidate material may therefore be useful in predicting the retention time of that
compound under similar conditions.
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Liu, Qiang. "Fundamental Study and Method Development for Surface-based Laser Desorption Ionization Imaging Mass Spectrometry." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-02262009-143514/.
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By providing both the chemical identity and the spatial organization of each component in biological samples, Imaging Mass Spectrometry (IMS) becomes an emerging tool in clinic and pharmacological study. Most work in IMS has been focused on protein and peptide mapping in biological samples to take advantage of effective analyte ionization in MALDI-MS, and also partially due to the limitation of MALDI-MS in small molecule detection. The focus of my research is to develop novel tools to image spatial distribution of small molecules in biological samples. A surface-based mass spectrometric imaging method, i.e. Desorption/Ionization on Silicon (DIOS), was used for biological surface analysis in the concept-proof investigation. More over, possible proton transferring pathways and impact of local chemical environment have been systematically investigated in the fundamental understanding of ionization mechanism of SALDI-MS. Based on the finding on the SALDI mechanism, a hybrid ionization approach, ME-SALDI has been developed by combing the strength of the conventional MALDI matrix and SALDI, where the improved detection sensitivity with reduced matrix-analyte interference and the improved imaging capability through analysis of mouse brain and heart sections has been demonstrated. In addition, the impact of vacuum stability of matrix in ME-SALDI-IMS applications has been examined. A solvent free, homogenous and reproducible sublimation method has been developed for ionic matrix in ME-SALDI, by which improved vacuum stability and MS detection have been achieved. Furthermore, a new generation of meso-porous oxide substrate was developed as a novel ME-SALDI substrate with a superior storage stability, extended detectable mass range and robust substrate preparation.
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Andersson, Jonas. "Ion recombination in liquid ionization chambers : development of an experimental method to quantify general recombination." Doctoral thesis, Umeå universitet, Radiofysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-68942.
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An experimental method (the two-dose-rate method) for the correction of general recombination losses in liquid ionization chambers has been developed and employed in experiments with different liquids and radiation qualities. The method is based on a disassociation of initial and general recombination, since an ionized liquid is simultaneously affected by both of these processes. The two-dose-rate method has been compared to an existing method for general recombination correction for liquid ionization chambers, and has been found to be the most robust method presently available. The soundness of modelling general recombination in liquids on existing theory for gases has been evaluated, and experiments indicate that the process of general recombination is similar in a gas and a liquid. It is thus reasonable to employ theory for gases in the two-dose-rate method to achieve experimental corrections for general recombination in liquids. There are uncertainties in the disassociation of initial and general recombination in the two-dose-rate method for low applied voltages, where initial recombination has been found to cause deviating results for different liquids and radiation qualities. Sensitivity to ambient electric fields has been identified in the microLion liquid ionization chamber (PTW, Germany). Experimental data may thus be perturbed if measurements are conducted in the presence of ambient electric fields, and the sensitivity has been found to increase with an increase in the applied voltage. This can prove to be experimentally limiting since general recombination may be too severe for accurate corrections if the applied voltage is low.
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Ross, William Charles. "Monte Carlo calculations of inner shell ionization profiles and the secondary electron background in electron spectroscopy." Thesis, University of York, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298446.
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Lee, Kim Chung. "Liquid chromatography coupled with electrospray-ionization mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry method development and applications for the analysis of food and medicinal herbs." HKBU Institutional Repository, 2009. http://repository.hkbu.edu.hk/etd_ra/995.
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Nordgren, Helena. "Mass spectrometry in the search for new drugs of abuse : method development and clinical application /." Stockholm, 2004. http://diss.kib.ki.se/2004/91-7349-827-0/.
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Chia, Ching Kean. "Impact ionisation in Alâ†xGaâ†1â†-â†xAs/GaAs heterojunction and multiple quantum well structures." Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287690.
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Ververs, James. "A quantitative method for reproducible ionization chamber alignment to a water surface for external beam radiation therapy depth dose measurements." VCU Scholars Compass, 2011. http://scholarscompass.vcu.edu/etd/2600.
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Ionization chambers (ICs) are the most commonly used detectors for radiation therapy dose measurements. Typical IC measurements use cylindrical ICs in a water phantom and therefore require initial IC alignment to the water surface. This alignment has long been ignored and only recently has a qualitative governing recommendation been made. This thesis describes a reproducible methodology for quantitative ionization chamber water surface alignment. Depth-ionization measurements are taken with twenty-eight IC designs under varying conditions including, but not limited to, changes in scan direction, speed, and resolution, radiation beam type, field size, energy, and electron contamination. Measurements are acquired using standard radiotherapy accelerators in the Virginia Commonwealth University Department of Radiation Oncology and at the National Research Council of Canada, where a customized scanning system capable of better than 0.15 mm IC positioning precision is used. Measurements are also performed with standard commercial scanning equipment on the Accuray CyberKnife, a specialized radiosurgery-class accelerator. An analytical model is developed from basic principles to test the theoretical foundations of IC response near a water surface. The theoretical foundation is further validated via Monte Carlo simulation models that fully account for all details of the ICs used to take measurements. It is determined that the dose gradient as a function of depth is maximized when a given IC reaches the water surface when moving from depth in water. This effect is unchanged under all of the measurement scenarios tested. Measurements taken at 0.1 mm resolution for several seconds per point over several millimeters near the surface will yield a gradient peak that can be used for quantitative alignment. Using developed software, multiple scans at variant resolutions can be stitched into typical clinical scans so as not to significantly affect clinical measurement workflow. The recommended measurement method is developed in a format suitable for inclusion into a clinical protocol for depth-ionization measurement acquisition.
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Thomas, Jennifer L. "Method Development for the Analysis of Smokeless Powders and Organic Gunshot Residue by Ultra Performance Liquid Chromatography with Tandem Mass Spectrometry." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/1017.
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The goal of this project was to develop a rapid separation and detection method for analyzing organic compounds in smokeless powders and then test its applicability on gunshot residue (GSR) samples. In this project, a total of 20 common smokeless powder additives and their decomposition products were separated by ultra performance liquid chromatography (UPLC) and confirmed by tandem mass spectrometry (MS/MS) using multiple reaction monitoring mode (MRM). Some of the targeted compounds included diphenylamines, centralites, nitrotoluenes, nitroglycerin, and various phthalates. The compounds were ionized in the MS source using simultaneous positive and negative electrospray ionization (ESI) with negative atmospheric pressure chemical ionization (APCI) in order to detect all compounds in a single analysis. The developed UPLC/MS/MS method was applied to commercially available smokeless powders and gunshot residue samples recovered from the hands of shooters, spent cartridges, and smokeless powder retrieved from unfired cartridges. Distinct compositions were identified for smokeless powders from different manufacturers and from separate manufacturing lots. The procedure also produced specific chemical profiles when tested on gunshot residues from different manufacturers. Overall, this thesis represents the development of a rapid and reproducible procedure capable of simultaneously detecting the widest possible range of components present in organic gunshot residue.
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Coons, Marc P. L. "Solvent Effects for Vertical Ionization Processes in Liquid Water and at the Liquid-Vapor Interface." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1503014629752161.
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Yasin, Mohammed. "Environmental monitoring of pesticides in components of river systems - method development and analysis by gas chromatography negative-ion chemical ionization mass spectrometry." Thesis, University of Salford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308379.
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GIAROLA, RODRIGO S. "Estudo teórico-experimental da resposta radiométrica de câmaras de ionização utilizadas em dosimetria em feixes de raios X para diagnóstico radiológico." reponame:Repositório Institucional do IPEN, 2014. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11786.
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Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2014-11-10T10:35:23Z
No. of bitstreams: 0<br>Made available in DSpace on 2014-11-10T10:35:23Z (GMT). No. of bitstreams: 0<br>Dissertação (Mestrado em Tecnologia Nuclear)<br>IPEN/D<br>Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Adel, Tehseen. "Design, Construction, and Implementation of Ionization Method Surface Potential Instrument For Studies of Charged Surfactants and Inorganic Electrolytes At the Air/Water Interface." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1512122927166396.
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Fang, Nannan. "Gas Phase Chiral Recognition, Characterization of Porous Polymer Monolith Nanospray Ionization, and the Negative Mode CRAFTI Method Using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry." Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd3176.pdf.
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Lima, Estela de Oliveira 1981. "Inovação no diagnóstico da hanseníase = potencial método não invasivo associado à espectrometria de massas de alta resolução = Innovation in leprosy diagnosis: potential non-invasive method associated to high resolution mass spectrometry." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/313027.
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Orientador: Rodrigo Ramos Catharino<br>Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas<br>Made available in DSpace on 2018-08-27T08:28:48Z (GMT). No. of bitstreams: 1
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Previous issue date: 2015<br>Resumo: A Hanseníase é uma doença infecciosa e crônica causada pelo Mycobacterium leprae. Este patógeno infecta principalmente macrófagos e células de Schwann e apresenta alta distribuição pela pele e nervos periféricos. Clinicamente, a forma mais comum de identificação da doença é a presença de espessamento de nervos e lesões hipocrômicas com perda de sensibilidade, entretanto, 30% dos pacientes infectados podem não apresentar manifestação clínica típica. Atualmente, o teste considerado padrão ouro no diagnóstico da Hanseníase é a baciloscopia, diretamente dependente de biópsia de pele, um método invasivo e com baixa sensibilidade para as formas mais brandas da doença. O desenvolvimento de um método rápido, sensível e não invasivo seria de grande importância para o diagnóstico assertivo da hanseníase. Portanto, o objetivo deste trabalho foi identificar marcadores lipídicos em pacientes com Hanseníase diretamente a partir de "imprint" de pele, usando a espectrometria de massas como estratégia analítica. Para a coleta do "imprint" de pele, uma placa de sílica foi levemente pressionada contra a pele dos pacientes ou dos indivíduos saudáveis (grupo controle). Os lipídeos adsorvidos pela placa de sílica foram extraídos e submetidos à ionização por eletroctrospray e infusão direta em espectrômetro de massas de alta resolução (ESI-HRMS). Todas as amostras foram diferenciadas por análise estatística multivariada baseada na plataforma de lipidômica, o que ajudou a eleger marcadores de diferentes classes de lipídeos. As análises identificaram leucotrieno E4, glicosilceramida, fosfatidilserina, phthiocerol e ácido ?-smegma micólico como marcadores do grupo com hanseníase, diferentemente do grupo de indivíduos saudáveis, cujos marcadores identificados pertencem às classes de fosfolipídeos e gangliosídeos, próprios da constituição natural da pele. Os resultados encontrados indicam que o "imprint" de pele em placa de sílica, associado à ESI-HRMS, é promissor como método rápido e sensível para o diagnóstico da Hanseníase. Assim sendo, o método desenvolvido apresenta grande potencial para auxiliar na redução da cadeia de transmissão da Hanseníase, uma vez que quanto mais precoce for o diagnóstico, mais cedo se inicia o tratamento<br>Abstract: Leprosy is a chronic infectious disease caused by Mycobacterium leprae, which primarily infects macrophages and Schwann cells, presenting higher distribution on skin and peripheral nerves. Clinically, the most common form of identification is through the observation of anesthetic lesions; however, up to 30% of infected patients may not present this clinical manifestation. Currently, the gold standard diagnostic test for leprosy is based on skin lesion biopsy, which is invasive and presents low sensibility for suspect cases. Therefore, the development of a fast, sensible and noninvasive method that identifies infected patients would prove helpful for assertive diagnosis. The aim of this work was to identify lipid markers in leprosy patients directly from skin imprints, using a mass spectrometric analytical strategy. For skin imprint samples, a 1 cm2 silica plate was gently pressed against patients¿ or healthy volunteers¿ skin. Imprinted silica lipids were extracted and submitted to direct-infusion electrospray ionization high-resolution mass spectrometry (ESI-HRMS). All samples were differentiated using a lipidomics-based data workup employing multivariate data analysis, which helped electing markers from distinct lipid classes. Results indicated that phospholipds, sphingolipids and mycolic acids, which were absent in healthy control subjects, clearly presented different intensities when compared to patients¿ samples. Results indicate that silica plate skin imprinting associated with ESI-HRMS is a promising fast and sensible leprosy diagnostic method, even for patients without clinical skin manifestations. With an early leprosy diagnosis, an early and effective treatment can be feasible and thus the chain of leprosy transmission can be abbreviated<br>Doutorado<br>Fisiopatologia Médica<br>Doutora em Ciências
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Hagman, Charlotte. "Method Development in Quantitative and Structural Proteomics using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry." Doctoral thesis, Uppsala University, Department of Engineering Sciences, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4761.
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<p>In this thesis, methods for studying different aspects of proteomics were developed with Fourier Transform Ion Cyclotron Resonance, (FTICR), mass spectrometry. The FTICR technique provides ultra-high mass resolving power, mass accuracy at sub ppm level and sensitivity in the attomole region.</p><p>Methods for quantifying biomarkers in body fluids such as cerebrospinal fluid, (CSF), and plasma were developed. Two sets of global markers with different properties were used for quantitative analysis; S-Methyl Thioacetimidate, (SMTA), and S-Methyl Thiopropionimidate, (SMTP), and [H<sub>4</sub>]- and [D<sub>4</sub>]-1-Nicotinoyloxy succinimide ester. Reduced ion suppression and higher sensitivity was obtained by coupling a High Performance Liquid Chromatography, (HPLC), system to the FTICR mass spectrometer.</p><p>In body fluids, proteins and peptides are present in a broad dynamic concentration range. Therefore, depleting abundant proteins prior to analysis results in decreased ion suppression and increased sensitivity. Two commercial depletion kits were evaluated with the SMTA- and SMTP-markers.</p><p>For both types of global markers, the experimental error for quantitative analysis of abundant proteins was less than 30%. This provides a lower limit for the protein up- and down regulations in complex solutions that can be monitored with HPLC-FTICR mass spectrometry.</p><p>Together with the identity and quantity of selected proteins the structure, dynamics and interactions with other molecules are of great importance. The later can be elucidated with Hydrogen/Deuterium Exchange, (HDX), mass spectrometry. Structural information at high resolution can be obtained with Collision-Induced Dissociation, (CID), HDX mass spectrometry. In this thesis, exchange rates of amide hydrogens in peptides were in excellent agreement with NMR results.</p><p>In some cases, the CID-fragments have different gas-phase exchange properties and as a consequence the solution phase exchange process can not be monitored. By applying Electron Capture Dissociation, (ECD), at ultra-high vacuum, the exchange process at a specific residue could be monitored.</p>
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Kundu, Ashoke. "Monte Carlo simulation of gas-filled radiation detectors." Thesis, University of Surrey, 2000. http://epubs.surrey.ac.uk/987/.
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Åkervall, Anton. "Development of a GC Method for the Quantification of Short Chain Carboxylic Acids in Aqueous Solution." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-166367.
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Petroleum powered vehicles emit volatile organic compounds (VOCs) through combustion that contributes to the pollution of the environment. A technique in the 1970s was developed to decrease these emissions, especially for nitrogen oxides (NOx) and sulphuric oxides (SOx) which is called exhaust gas recirculation (EGR). The technique works by recirculating a portion of the combusted gas back into the engine, this limits the NOx and SOx emissions because of lower temperatures and less available oxygen. The problems that follow these effects is the formation and condensation of acids that corrode the material of the EGR system, which are created by many different reactions. It is of importance to understand how the compounds in the EGR system behaves through analysis of authentic and simulated condensates, which is why a quantitative method for these compounds are of interest. The aim of the project was to develop a simple quantitative analysis method for formic acid, acetic acid, and lactic acid in aqueous solution, which was done at Gränges Sweden AB. The technique used for detection and quantification was gas chromatography (GC) coupled to a flame ionization detector (FID) and a water compatible polyethylene glycol (PEG) column. Fractional factorial design (FFD) was used for determination of adequate operating parameters of the GC method and the sample preparation. Sample preparation only required filtration and pH adjustment prior to direct aqueous injection (DAI) to the chromatographic instrument. Detection of the analytes was very difficult because of non-compatibility with the FID, and quantification of asymmetric peak shapes made this problem worse, omitting lactic acid from further analysis. Limit of detection (LOD) and limit of quantification (LOQ) was 490 and 1640 ppm for formic acid and 120 and 400 ppm for acetic acid, with an injection volume of 0.3 μL and split ratio 10:1. Limits were too high for every EGR sample leaving no peaks detected for the sample preparation used. Further development should be done with complementary techniques and sample reprocessing in order to quantify the compounds.
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Giarola, Rodrigo Sanchez. "Estudo teórico experimental da resposta radiométrica de câmaras de ionização utilizadas em dosimetria em feixes de raios X para diagnóstico radiológico." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/85/85133/tde-15102014-141806/.
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O Programa de Controle de Qualidade de sistemas geradores de raios X inclui a verificação periódica da constância dos feixes de raios X, para tanto é preciso que o físico especialista conheça as respostas dos instrumentos medidores de radiação. Neste trabalho foi analisado o comportamento das câmaras de ionização submetidas a feixes de radiação em Radiodiagnóstico nas energias de 50, 81, 90 e 102 kV. Inicialmente foram realizadas medidas experimentais com oito câmaras de ionização de quatro modelos- e, em seguida, foi simulado através do Método de Monte Carlo, com o código MCNP5, um sistema gerador de raios X e os quatro modelos de câmaras de ionização empregados na parte experimental. Com as simulações de arranjo padronizado foi calculado o valor de kerma no ar e foram comparadas, então, as respostas obtidas experimentalmente com os cálculos por simulação. As correlações obtidas entre os resultados permitiram o desenvolvimento de uma ferramenta que apresenta maiores informações para a compreensão dos equipamentos detectores utilizados, e que auxilia o especialista em física médica na análise da resposta dos detectores.<br>The Quality Control Program for X ray generator systems includes the periodic verification of the X rays beams constancy, therefore it is necessary that the medical physics specialist knows the measuring instruments physical response to radiation. In this work it was analyzed the behavior of ionization chambers subjected to radiation beams at diagnostic radiology energies of 50, 81, 90 and 102 kV. Initially it was performed experimental measurements with eight ionization chambers four models- and then it was simulated, by Monte Carlo Method, with the MCNP5 code an X ray generator system and the four ionization chambers models used in the experimental part. A patterned array was taken by the simulations and the air kerma value was calculated to the simulated system and then those values were compared to the experimental data. The correlations between the results allowed the development of a tool that enables a better understanding of the detectors and helps the physics specialist in the analysis of the detectors response.
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Nygren, Yvonne. "Advances in analytical methodologies for studies of the platinum metallome in malignant cells exposed to cisplatin." Doctoral thesis, Umeå universitet, Kemiska institutionen, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-37400.
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The scientific progress about the important chemotherapeutic drug substance cisplatin (CDDP) and its function has often been rendered by data difficult to interpret, and still many questions about its mode of action remains to be clarified by the scientific community. However, studies of CDDP possess a high complexity due to; i) low intracellular concentration, ii) many potential biomolecule targets, iii) poor or unknown stability of the intact drug and its biomolecule adducts and iv) complex and varying sample matrices. Metallomic studies, using advanced analytical techniques may contribute to clarify the interactions between CDDP and intracellular biomolecules. For a successful outcome sample preparation conditions as well as separation and detection techniques must be carefully selected and optimized to achieve accurate results and correct interpretation of data. This thesis describes some new and improved analytical methodologies for characterizing the Pt metallome in CDDP-exposed malignant cells. The developed methods are based on powerful liquid chromatography (LC) methods hyphenated to sensitive detection by inductively coupled plasma- (ICP) and electrospray ionization mass spectrometry (ESIMS). Consideration has also been taken about sample preparation conditions. By selecting “chemically inert” sample preparation (cell lysis by osmosis) and separation (using only nonreactive or no additatives) conditions we could avoid the formation of platinum artifact compounds previously described in the literature (Paper I and II). Using oxygen containing organic solvents with high boiling points (dimethylformamide; DMF, 1,4-dioxane, n-propanol and ethanol) as alternatives to acetonitrile in the LC separations, significant improvements were achieved in ICPMS sensitivity and robustness. When evaluated in combination with chromatographic performance and ESIMS detection the overall best performance was achieved with n-propanol (Paper II, III and IV). From the studies in Paper II we could show that free intact CDDP can be found in malignant cells, as supporting evidence for passive or endocytotic uptake of the drug and further estimate a half-life for intracellular CDDP to about 15 minutes. Such data has not been shown before. In Paper V, the above improved LC methods were used to demonstrate differences in the platinum and cupper metallome from sensitive and resistant T289 melanoma cells exposed to CDDP at near clinical levels. In a wider perspective we have shown the potential of using hydrophilic liquid interaction chromatography (HILIC) hyphenated to ICPMS detection as a general approach for analysis of hydrophilic metallo-compounds (Paper II). Taking advantage of the superior ICPMS performance using n-propanol gradients for reversed phase liquid chromatography (RPLC) possess a true alternative and /or complimentary technique to size exclusion chromatography (SEC) commonly applied within metallomic studies of biomolecules (Paper V). Using n-propanol in HILIC as well as in RPLC enables parallel detection by ICP- and ESIMS using only one set of chromatographic parameters (Paper III and IV), something commonly called for by scientists in the field.
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Streit, Livia 1986. "Estudo de energias de dupla ionização e de ligação de elétron por Monte Carlo Quântico e métodos pós-hartree-fock." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249230.
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Orientador: Rogério Custodio<br>Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química<br>Made available in DSpace on 2018-08-21T05:01:18Z (GMT). No. of bitstreams: 1
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Previous issue date: 2012<br>Resumo: O estudo de processos fotoeletrônicos, como energias de dupla ionização é de grante interesse teórico e experimental na área da física molecular. Cálculos e medidas experimentais de energias de dupla ionização e de energias de ligação de elétron envolvem o entendimento de correlação e relaxação eletrônica. A consideração de tais efeitos é indispensável para a obtenção de resultados precisos. No presente trabalho, tais processos fotoeletrônicos são estudados com métodos Pós-Hartree-Fock e Monte Carlo Quântico (MCQ). No último caso, o método foi adaptado de maneira a utilizar um tipo diferente de função de onda. A primeira parte desta tese envolve o estudo de energias de dupla ionização. O objetivo prinicipal é a análise do tipo de função de onda tentativa no método MCQ. Três diferentes formas foram estudadas: Uma função Hartree-Fock monodeterminante com uma função de correlação eletrônica explícita de Boys-Handy otimizada para a molécula; uma função CI multideterminante; e ainda, uma função de onda multideterminante construída a partir de orbitais de Dyson. Para obter a função de onda de Dyson, um extenso trabalho envolvendo estudo e programação do programa de cálculo de estrutura eletrônica Gaussian 09 foi necessário. A primeira parte da tese ainda envolve o estudo de energias de dupla ionização por métodos Interação de Configurações Multireferência MRCI e Gaussian-3 G3. Os resultados obtidos são comparados aos resultados obtidos por MCQ. A segunda parte da tese compreende o estudo de energias de ligação de elétron de complexos de gases nobres com o ânion Uracila. A coexistência de ânions em que o orbital singularmente ocupado apresenta características de um orbital de valência e de um orbital muito difuso é investigada através de análise de geometria e do cálculo de energias de afinidade eletrônica e de ligação de elétron dos complexos neutros e aniônicos<br>Abstract: The study of photoelectron processes such as double ionization energies has become a very interesting field in experimental and theoretical molecular physics. Calculation and experimental measure of double ionization energies and electron binding energies involve understanding of electron correlation and relaxation energies. Consideration of those effects are a requisite in order to predict precise values. In this work, those photoelectron processes are studied with post-Hartree-Fock and Quantum Monte Carlo (QMC) methods. In the latter case, the method was also modified to take in account a different type of wavefunction. The first part of this thesis is concerned with the study of double ionization energies. The main objective of this work is the analysis of the type of trial wavefunction in QMC method. Three different forms were studied: A single determinant Hartree-Fock function, with the Boys-Handy explicit electron correlation function optimized for the molecule; a multi-determinant CI wavefunction; and finally, a multi-determinant wavefunction built from Dyson orbitals. In order to obtain the Dyson wavefunction, an extensive work on studying and programming the electron structure package Gaussian 09 was necessary. The first part still comprises the study of double ionization energies with MRCI and G3 methods. The results thus obtained were compared to the QMC results. The second part of this thesis embraces the study of electron binding energies of uracil¿noble-gas complexes. The coexistence of valence and diffuse¿bound anions of U(Xe), suggested by experimental studies is investigated with geometry analysis and calculation of adiabatic electron affinities and vertical electron detachment energies of the neutral an anionic complexes<br>Doutorado<br>Físico-Química<br>Doutor em Ciências
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O'Connor, Caroline Sophie Scott. "The properties of molecular ions." Thesis, University College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314259.
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Brown, Jenelle Daria. "Development of a method for the simultaneous detection of mycotoxins in corn using supercritical fluid extraction (SFE), high performance liquid chromatography (HPLC), and electrospray-atmospheric pressure ionization/mass spectrometry (ES-API/MS) for extraction, separation, and identification." Thesis, University of Iowa, 1999. https://ir.uiowa.edu/etd/2802.
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Arvidsson, Björn. "Quantitative Bioanalysis : Liquid separations coupled to targeted mass spectrometric measurements of bioactive compounds." Doctoral thesis, Uppsala universitet, Analytisk kemi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8581.
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Performing quantitative analysis of targeted bioactive compounds in biological samples, such as blood plasma, cerebrospinal fluid or extracts from pig liver, put high demands on the ruggedness of the method acquiring the results. In addition to the complexity of the sample matrix, the bioactive compounds targeted for analysis usually have low levels of natural abundance, further increasing the demand on the analytical method sensitivity. Furthermore, quantitation of analytes at trace levels in the presence of large amounts of interfering species in biofluids must aim for repeatable precision, high accuracy ensuring the closeness to the true values, a linear response spanning over several orders of magnitude and low limits of quantitation to be valid for monitoring disease states in clinical analysis. An analytical method most commonly follow a certain order of events, called the analytical chain, which includes; experimental planning, sampling, sample pre-treatment, separation of species, detection, evaluation, interpretation and validation, all equally important for the outcome of the results. In this thesis, the scope has been to create novel methods, or to refine already existing methods, in order to achieve even better performances of the different events in the analytical chain. One of the aspects has been to sample and enrich analytes in vivo by the use of solid supported microdialysis, giving the advantage of almost real-time monitoring of analyte levels within a living host with targeted selectivity due to the analyte affinity for solid particles. Another aspect to selectively clean and enrich analytes in a complex matrix has been developed and automated on-line by the use of a column-switching technique before the analytical separation. By using several steps of extraction and separation coupled on-line to selected detection by the use of a triple quadrupole mass spectrometer facilitates great selectivity of species. The mass spectrometer also gives the ability to distinguish between isotopically labelled analogues coeluting with the analytes yielding the necessary accuracy for quantitative evaluation. Both development of analytical methods and clinical applications has been performed, as well as improvements of existing techniques, all to improve the quantitation of trace levels of targeted analytes in biofluids.
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Gaubeur, Ivanise. "Determinação das constantes de dissociação/ionização da di-2-piridil cetona benzoilhidrazona (DPKBH) em diferentes porcentagens de etanol." Universidade de São Paulo, 1997. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-15022016-165753/.
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A di-2-piridil cetona benzoilhidrazona (DPKBH) é um reagente solúvel em uma série de solventes orgânicos mas pouco solúvel em água. Vem sendo utilizado para a determinação de metais, (principalmente do grupo de transição) como Fe(II), Fe(III), Ni(II), Cu(II), entre outros e como ligante de referência para estudar o comportamento dos íons Fe(II) e Fe(III) em presença de espécies orgânicos encontrados em águas naturais. Com o objetivo de entender melhor as propriedades do DPKBH em meio de etanol, foi necessário determinar as constantes de dissociaçãolionização em diferentes porcentagens desse solvente orgânico (10, 19, 29 e 48 %). Nestas porcentagens de etanol, através de medidas absolutas de pH determinaram-se os pKs do DPKBH utilizando-se a técnica potenciométrica e em 10 e 48 % de etanol através de medidas absolutas de pH associadas às absorbâncias das espécies presentes nos equilíbrios, utilizando-se a técnica espectrofotométrica. Nas devidas porcentagens de etanol, o comportamento do eletrodo foi previamente determinado. Os valores de pK1 3,210; 3,342; 3,398 e 3,360 e de pK2 10,834; 11,013; 11,793 e 11,382 foram obtidos respectivamente para 10, 19, 29 e 48 % de etanol, utilizando-se a técnica potenciométrica. Através da técnica espectrofotométrica os valores de pK1 foram 3,257 e 3,322 e pK2 10,880 e 11,820, em 10 e 48 % de etanol, respectivamente.<br>The di-2-pyridyl ketone benzoylhydrazone (DPKBH) is a soluble reagent in different organic solvents but slightly soluble in water. It has been used for metal determinations, (mainly transition metals) such as for Fe (II), Fe(III), Ni(II), Cu(II) and also like a reference ligand to study the behavior of Fe(II) and Fe(III) ions in the presence of organic species found in natural waters. So as to better understand the DPKBH properties In ethanol, it was necessary to determine the dissociation/ionization constant in different percentages of ethanol (l0, 19, 29 and 48%). In these ethanol percentages, through absolute pH measurements, pKs of DPKBH could be the found by using the potentiometric technique, and in 10 and 48% of ethanol the pKs of DPKBH were determined with pH measurements associated to absorbance of the species present in the equilibria by using the spectrophotometric technique. In appropiate percentage of ethanol the behavior of the glass electrode was previously determined. The pK1 values 3.210; 3.342; 3.398 and 3.362, and pK2 10.834; 11.013; 11.793 and 11.382 were found for 10,19,29,48 % of ethanol, by using the potentiometric technique. The spectrophotometric technique led to pK1 values 3.257 and 3.322, and the pK2 ones 10.880 and 11. 820 in 10 and 48 % of ethanol respectively.
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Divišová, Radka. "Analýza vonných látek v kosmetických prostředcích metodou plynové chromatografie." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2009. http://www.nusl.cz/ntk/nusl-216530.
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This thesis is focused on aroma compounds which are presented in a wide variety of products including perfume, cologne, cosmetics, toiletries, laundry products and detergens. The widespread use and exposure to aroma compounds of aforementioned products could cause a range of the adverse reactions such as contact dermatitis, asthma, eczema and breathing problems. There are a lot of aroma compounds triggering negative allergic reactions but EU regulations limit 26 the most important fragrance allergens. The presence of these substances has to be declared on the product label if a limit of 0,01 % for rinse off and 0,001 % for leave-on products is exceeded. Of these 26 substances, a methodology was elaborated for determination of 12 allergens in a experimental part of this thesis. A method by solid-phase microextraction (SPME) and gas chromatography-flame ionization detection (GC-FID) was applied for fragrance allergens identification, extraction and measurement. The optimal extraction conditions of SPME-GC method were investigated including equilibrium time, extraction time and extraction temperature to increase extraction efficiency. Another important point is the method by SPME-GC-FID was validated and following performance parameters were determined: repeatability, linearity, limit of detection (LOD) limit of quantitation (LOQ). SPME-GC-FID was tested and applied to real samples.
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Hampton, Christina Young. "Applications and fundamental characterization of open air and acoustic-driven ionization methods." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29683.
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Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2010.<br>Committee Chair: Fernandez, Facundo M.; Committee Member: Bottonley, Lawrence A.; Committee Member: Kelly, Wendy L.; Committee Member: Merrill, Alfred; Committee Member: Orlando, Thomas; Committee Member: Sullards, Cameron. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Ek, Patrik. "New methods for sensitive analysis with nanoelectrospray ionization mass spectrometry." Doctoral thesis, KTH, Analytisk kemi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-25917.
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In this thesis, new methods that address some current limitations in nanoelectrospray mass spectrometry (nESI-MS) analysis are presented. One of the major objectives is the potential gain in sensitivity that can be obtained when employing the proposed techniques. In the first part of this thesis, a new emitter, based on the generation of electrospray from a spray orifice with variable size, is presented. Electrospray is generated from an open gap between the edges of two individually mounted, pointed tips. The fabrication and evaluation of two different types of such emitters is presented; an ESI emitter fabricated from polyethylene terephtalate (Paper I), and a high-precision silicon device (Paper II). Both emitters were surface-treated in a selective way for an improved wetting of the gap and to confine the sample solution into the gap. In the second part of this thesis, different methods for improved sensitivity of nESI-MS analysis have been developed. In Paper III, a method for nESI-MS analysis from discrete sample volumes down to 1.5 nL is presented, using commercially available nESI needles. When analyzing attomole amounts of analyte in such a small volume of sample, an increased sensitivity was obtained, compared to when analyzing equal amounts in conventional nESI-MS analysis. To be able to analyze smaller sample volumes, needles with a narrower orifice and a higher flow resistance were needed. This triggered the development of a new method for fabrication of fused silica nESI needles (Paper IV). The fabrication is based on melting of a fused silica capillary by means of a rotating plasma, prior to pulling the capillary into a fine tip. Using the described technique, needles with sub-micrometer orifices could be fabricated. Such needles enabled the analysis of sample volumes down to 275 pL, and a further improvement of the sensitivity was obtained. In a final project (Paper V), nESI-MS was used to study the aggregation behavior of Aβ peptides, related to Alzheimer’s disease. An immunoprecipitation followed by nESI-MS was employed. This technique was also utilized to study the selectivity of the antibodies utilized.<br>QC 20101112
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Allard, Erik. "Metabolic Studies with Liquid Separation Coupled to Mass Spectrometry." Doctoral thesis, Uppsala universitet, Analytisk kemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-110310.
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Metabolism is the sum of all chemical processes with the purpose to maintain life, as well as enable reproduction, in a living organism. Through the study of metabolism, increased understanding of pharmacological mechanisms and diseases can be achieved. This thesis describes several ways of doing so, including targeted analysis of selected metabolites and investigations of systematic metabolic differences between selected groups through pattern recognition. A method for exploring metabolic patterns in urine samples after intake of coffee or tea was developed. The methodology was later used with the aim to find biomarkers for prostate cancer and urinary bladder cancer. Furthermore, a fully automated quantitative method was developed for concentration measurements of the double prodrug ximelagatran and its metabolites in pig liver. The method was then used to study the roll of active transporters in pig liver cells. Moreover, a fundamental study was conducted to investigate how monitoring of small, doubly charged analytes can improve the limit of detection and precision in a quantitative method. The techniques used for the experiments were liquid separation coupled to electrospray mass spectrometry. Extra efforts were made to make the separation and the ionization as compatible as possible to each other for increased quality of the collected data.
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Gazzana, Daniel da Silva. "Contribuição ao estudo de análise de aterramento impulsivo e em altas frequências associado à avaliação da suportabilidade dos seres humanos com base no método da modelagem por linhas de transmissão (TLM)." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/70922.
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Este trabalho fundamenta-se no desenvolvimento e aprimoramento de metodologias para a melhor representação do aterramento elétrico sob uma análise transiente. O estudo concentrase no estabelecimento de contribuições ao estado da arte associadas à análise e modelagem de aterramento impulsivo e em altas frequências. O estudo vincula-se também à avaliação da suportabilidade de seres humanos submetidos a potenciais produzidos na superfície do solo, provenientes da corrente elétrica gerada por um surto atmosférico. A concepção das metodologias propostas baseou-se no uso do Método da Modelagem por Linhas de Transmissão em uma dimensão (TLM-1D). Destacam-se três grandes tópicos da pesquisa. O primeiro concentra-se no desenvolvimento de formulação para a inclusão do fenômeno de ionização do solo ao Método TLM-1D clássico. A formulação desenvolvida tem como característica ser uma técnica generalista, independente das propriedades do meio, dimensões do eletrodo e do surto atmosférico. O segundo foco concentra-se no aprimoramento e desenvolvimento de equacionamento analítico para a estimação de potenciais gerados na superfície do solo, originados pela corrente elétrica estabelecida sobre eletrodo de aterramento. Tal equacionamento tem grande aplicabilidade em conjunto com metodologias numéricas unidimensionais, as quais não são capazes de determinar diretamente os referidos potenciais. Por fim, a realização de estudo de suportabilidade e segurança de seres humanos em contato com eletrodos de aterramento submetidos a surto atmosférico, considerando modelo representativo baseado em circuitos elétricos, consolida o trabalho desenvolvido.<br>This work is based on the development and improvement of methodologies for the best representation of the electrical grounding under a transient analysis. The study concentrated on establishing contributions to the state of the art related to the analysis and modeling of impulsive and high frequencies grounding systems. The study is also associated to the evaluation of the supportability of human beings submitted to the potentials produced on the soil surface from the electric current generated by a lightning. The conception of the proposed methodology was based on the Transmission Line Modeling Method in one dimension (TLM- 1D). Three major research topics can be highlighted. The first involves the development of a formulation to include the soil ionization phenomenon in the classic TLM-1D algorithm. The developed formulation is a generalist technique, independent of the medium properties, characteristic of the electrode and lightning surge. The second aims at the improvement and development of analytical equations for estimating the generated potential on the soil surface, originated by the electric current calculated in the grounding electrode. Such equationing has great applicability in conjunction with one-dimensional numerical methods which are not able to determine such potential directly. Finally, the achievement of a supportability study and personal safety of humans in contact with the grounding electrodes subjected to a lightning, considering a representative model based on electrical circuits, consolidates the developed work.
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Eriksson, Lars. "Methods for Ionization Current Interpretation to be Used in Ignition Control." Thesis, Linköpings universitet, Fordonssystem, 1995. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-141637.
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It is desirable to measure engine performance for several reasons, e.g. when computing the spark advance setting in spark-ignited (SI) engines. There exists two methods, among others, of measuring the performance, such as measuring the pressure and the ionization current. Since the ionization current reflects the pressure, it is interesting to study if it is possible to extract information from the ionization current about the combustion and pressure. Three different algorithms for extracting information from the ionization current are studied. The first algorithm, ion peak, searches the \second peak" in the ionization signal. The second algorithm computes the centroid. In the third algorithm a model of the ionization signal structure is fitted to the ionization signal. The algorithms are tested in four operating conditions. The first algorithm uses the local information around the second peak and is sensitive to noise. The second algorithm uses a larger portion of the ionization signal, which is more stable. It provides promising results for engines with a clear post flame phase. The third algorithm, ion structure analysis, fits an ideal model to the ionization signal. The algorithm provides promising results, but the present implementation requires much computational effort.
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Kim, Hyun Sik. "High performance fourier transform mass spectrometry : soft ionization methods and resolution enhancement /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487859879937953.
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Roos, Andreas. "Single photon double valence ionization of methyl monohalides." Thesis, Uppsala universitet, Molekyl- och kondenserade materiens fysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-239195.
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This thesis is based on experimental results from measurements on methyl halides at a photon energy corresponding to the He IIβ emission line. Double ionization processes involving the valence electrons of the molecules CH3F, CH3Cl and CH3I are studied by means of a magnetic bottle TOF-PEPECO spectrometer. Resulting double ionization data of these molecules suggest that mainly direct double photoionization is observed as a continuous energy sharing between the ejected electron pairs. As a mean to further understand the double ionization processes, a "rule of thumb", for double ionization in molecules, is applied to the data presented in the double ionization spectra. This is done in order to quantify the effective distance between the two vacancies created in the dications. It is found that the distance between the vacancies may be related to the bond distance between the carbon and halogen atoms. Further investigations call for quantum chemical calculations to scrutinize this hypothesis.<br>Det här examensarbetet är baserat på experimentella fotojonisations studier av metyl halider vid en fotonenergi motsvarande He IIβ emissionslinjen. Valenselektronerna i dubbeljonisations processerna för CH3F, CH3Cl och CH3I har studerats under användning av en så-kallad magnetisk flask TOF-PEPECO spektrometer. Resultaten av dessa mätningar visar att mestadels direkt dubbeljonisation processer före- kommer, där elektronerna delar kontinuerligt på energin som friges vid jonisationen. Den dubbla jonisa- tions processen är ytterligare studerad genom att tillämpa en tumregel för dubbeljonisation i molekyler, vilket ger en indikation av hur stort avståndet är mellan de två vakanserna som skapades när molekylerna joniserade. Resultaten från tumregeln visar att avståndet mellan vakanserna kan vara relaterade till bind- ningsavståndet mellan kol-atomen och halogen-atomen, i respektive metyl halogen. För att ytterligare bekräfta dubbeljonisations processerna i dessa molekyler, krävs kvantmekaniska beräkningar.
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Kulyk, Dmytro S. "Development and Applications of Contained Ionization Sources for Direct Complex Mixture Analysis by Mass Spectrometry." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1556751954644261.
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Teke, Nakul Kushabhau. "Explicitly correlated Green's function methods for calculating electron binding energies." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/101962.
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Single-particle Green's function method is a direct way of calculating electron binding energy, which relies on expanding the Fock subspace in a finite single-particle basis. However, these methods suffer from slow asymptotic decay of basis set incompleteness error. An energy-dependent explicitly correlated (F12) formalism for Green's function is presented that achieves faster convergence to the basis set limit. The renormalized second-order Green's function method (NR2-F12) scales as iterative N^5 where N is the system size. These methods are tested on a set of small (O21) and medium-sized (OAM24) organic molecules. The basis set incompleteness error in ionization potential (IP) obtained from the NR2-F12 method and aug-cc-pVDZ basis for OAM24 is 0.033 eV compared to 0.067 eV for NR2 method and aug-cc-pVQZ basis. Hence, accurate electron binding energies can be calculated at a lower cost using NR2-F12 method. For aug-cc-pVDZ basis, the electron binding energies obtained from NR2-F12 are comparable to EOM-IP-CCSD method that uses a CCSD reference and scales as iterative N^6.<br>Master of Science
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Wendling, Karen Saretta Glish Gary L. "Methods to detect volatile organic compounds using selected-ion chemical ionization mass spectrometry." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2008. http://dc.lib.unc.edu/u?/etd,1903.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2008.<br>Title from electronic title page (viewed Dec. 11, 2008). " ... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Chemistry." Discipline: Chemistry; Department/School: Chemistry.
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Beres, Martin Joseph. "Novel Analytical Methods for Improved Analysis of Biological Compounds." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1447408723.
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Mathis, John A. "Development of Chromatography and Mass Spectrometry Methods for Explosives Analysis." Ohio University / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1088184726.
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Asare, Shardrack O. "BOTTOM-UP LIGNOMICS: TOWARDS THE DEVELOPMENT OF ADDUCT ELECTROSPRAY IONIZATION MASS SPECTROMETRIC METHODS TO CHARACTERIZE AND SEQUENCE LIGNIN OLIGOMERS." UKnowledge, 2019. https://uknowledge.uky.edu/chemistry_etds/115.
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Lignin, the second most abundant naturally occurring polymer found in plant cell wall has the potential of becoming an alternative source for the production of chemical synthons for the pharmaceuticals and other chemical industries. While much gain has been made towards the development of degradation methods to break down lignin, effective analytical methods are still required to rapidly and accurately identify the products of lignin breakdown experiments. The goal of this work was to develop mass spectrometric methods for the characterization of lignin oligomers based on the study of model lignin compounds.
Unlike peptides and oligosaccharides, lignin model compounds that could serve as analytical standards for methods developments are not commercially available, and hence, the first project of this dissertation focused on the synthesis of lignin model compounds containing the β-O-4 bond. The priority was to synthesize compounds containing all important functionalities that reflect the structure of native lignin. By employing the known Aldol reaction, lignin oligomers containing the β-O-4 were synthesized. The synthesized β-O-4 lignin oligomers contained the characteristic functional groups of native β-O-4 lignin, that is, the phenolic functionality, the aryl glycerol β-O-4 aryl ether bond and the unsaturated side chain.
The second project was aimed at developing alternative ionization methods for the characterization of lignin in the negative ion mode mass spectrometry. A chloride adduct ionization method was developed and used for characterizing and sequencing lignin oligomers. This method proved to be very useful in stabilizing the adduct ion in the full scan spectrum mode and also providing useful structural information upon tandem mass spectrometry.
In the third project, a cationization technique was developed to unambiguously assign the sequence in which β-O-4 lignin oligomers are connected. A simple and easy to use sequencing chart was designed and could serve as a guide for predicting the sequence of larger lignin oligomers. This method offers an alternative approach for the characterization of lignin oligomers in the positive ion mode mass spectrometry.
The fourth project focused on the ionization response of a new class of β-O-4 lignin compounds. β-O-4 compounds having the same skeletal backbone but different non-polar groups at the a-position were synthesized, and their ESI response studied. Results from this study show that a slight change in the structure of a β-O-4 lignin model compound can change the cationization response to several order of magnitude. Most importantly, this work for the first time has shown a direct correlation between lignin ionization response and lignin structure.
The fifth project was aimed at studying the chromatographic behavior of the diastereomer pair in β-O-4 lignin model compounds. Using three commercially available HPLC columns, the chromatographic behavior and factors that affect the separation of the diastereomer pair of the β-O-4 lignin diastereomer on an HPLC column were studied. By performing tandem mass spectrometry on each of the diastereomers, a fragmentation mechanism was developed that could be used to unambiguous assign the configuration (erythro or threo) for the pair of diastereomer in a β-O-4 model.
The results presented in this dissertation adds significant knowledge to the lignin mass spectrometry literature, and it offers new ionization techniques for the characterization of lignin oligomers, most importantly, an alternative approach for lignin analysis using adduct ionization mass spectrometry. The developed methods could easily be extended for the characterization of larger lignin oligomers.
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Underwood, Jonathan. "Vector properties in molecular photodissociation." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311835.
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Bankefors, Johan. "Structural classification of Quillaja saponins by electrospray ionisation ion trap multiple-stage mass spectrometry in combination with multivariate analysis /." Uppsala : Department of Chemistry, Swedish University of Agricultural Sciences, 2006. http://epsilon.slu.se/10284550.pdf.
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Bankefors, Johan. "Methods for structural characterisation of Quillaja saponins by electrospray ionisation ion trap multiple-stage mass spectrometry /." Uppsala : Dept. of Chemistry, Swedish University of Agricultural Sciences, 2008. http://epsilon.slu.se/200844.pdf.
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Wälz, Gero [Verfasser], and Martin [Akademischer Betreuer] Schütz. "Development of local coupled cluster response methods for vertical Ionization Potentials / Gero Wälz ; Betreuer: Martin Schütz." Regensburg : Universitätsbibliothek Regensburg, 2017. http://d-nb.info/1131875834/34.
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Wetzel, William C. "Overcoming interferences in plasma source mass spectrometry alternative ionization sources, novel correction methods, and new instrumentation /." [Bloomington, Ind.] : Indiana University, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3223057.
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Thesis (Ph. D.)--Indiana University, Dept. of Chemistry, 2006.<br>"Title from dissertation home page (viewed June 28, 2007)." Source: Dissertation Abstracts International, Volume: 67-06, Section: B, page: 3109. Adviser: Gary M. Hieftje.
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Geng, Dawei. "Gas chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry methods for the determination of environmental contaminants." Doctoral thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-51727.
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The recent developments and improvements of instrumental methods for the analyses of the environmental contaminants, especially the persistent organic pollutants (POPs), have made it possible to detect and quantify these at very low concentrations in environmental and biotic matrices. The main objective of this thesis is to demonstrate the capability of the atmospheric pressure chemical ionization technique (APCI), using gas chromatography coupled to tandem mass spectrometry for the determination of a wide range of environmental contaminants, including the POPs regulated by Stockholm Convention, such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), but also the derivates of PBDEs and novel brominated flame retardants (NBFRs). The APCI was operated in charge transfer condition, preferably producing molecular ions. Multiple reaction monitoring (MRM) experiments were optimized by adjusting cone voltage, collision energy and dwell time. Optimization of source parameters, such as gas flows and temperatures was also performed. Low concentration standards were analyzed, achieving a visible chromatographic peak for 2 fg 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) demonstrating the excellent sensitivity of the system. Adequate linearity and repeatability were observed for all the studied compounds. The performance of APCI methods was validated against the conventional methods using gas chromatography coupled to high resolution mass spectrometry for chlorinated compounds in a wide range of matrices including environmental, air, human and food matrices. The GC-APCI-MS/MS method was successfully applied to a set of 75 human serum samples to study the circulating levels of POPs in epidemiologic studies. Moreover the method was utilized to establish temporal trends of POPs in osprey eggs samples collected during the past five decades.
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Reynal, François. "Etude des processus non-linéaires dans les atomes complexes en interaction avec un champ XUV intense et bref." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2012. http://tel.archives-ouvertes.fr/tel-00748138.
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Etude th'eorique de l'interaction entre un atome à deux ou trois électrons actifs et un champ laser de fort éclairement (10^13 à 10^15 W.cm−2) et de durée d'impulsion ultra-brève (femto à attoseconde) dans le domaine spectral XUV. Notre approche est basée sur la résolution de l' équation de Schrödinger dépendante du temps (ESDT). Nous utilisons une méthode spec- trale pour résoudre l'ESDT avec des fonctions d'onde construites sur des B- splines. Nous étudions particulièrement la double ionisation à deux photons (TPDI) de l'hélium dans l'état fondamental ainsi que dans l' état excité 1s2s. Plusieurs modèles sont d'eveloppés pour traiter le cas des impulsions ultra- brèves. Enfin nous abordons la TPDI du Lithium, système à trois électrons actifs. Nous comparons la double ionisation à deux photons dans le régime séquentiel pour Li et He(1s2s) ; le régime direct est également abordé
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SANTOS, LUCAS R. dos. "Desenvolvimento de um protocolo de calibração utilizando espectrometria e simulação matemática, em feixes padrões de raios x." reponame:Repositório Institucional do IPEN, 2017. http://repositorio.ipen.br:8080/xmlui/handle/123456789/28026.
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Submitted by Pedro Silva Filho (pfsilva@ipen.br) on 2017-11-21T11:20:13Z
No. of bitstreams: 0<br>Made available in DSpace on 2017-11-21T11:20:13Z (GMT). No. of bitstreams: 0<br>A calibração, por definição, é o processo pelo qual se estabelece uma relação entre valores de medição de um padrão, com as suas respectivas incertezas, e as indicações com as incertezas associadas do instrumento de medição a ser calibrado. Um protocolo de calibração descreve a metodologia a ser aplicada em um processo de calibração. O método escolhido para a obtenção deste protocolo foi o da espectrometria de feixe de raios X associada à simulação pelo método de Monte Carlo, fundamentado no fato de que ambos são considerados métodos absolutos na determinação de parâmetros de feixes de radiação. Neste trabalho foi utilizado o método de Monte Carlo utilizado para obter a função resposta do detector utilizada para a correção dos espectros obtidos do feixe primário de radiação X; deste modo foram calculadas as taxas de kerma destes feixes e comparadas aos valores obtidos com as câmaras de ionização padrão secundário do Laboratório de Calibração de Instrumentos do IPEN (LCI/IPEN). Foram obtidos os coeficientes de calibração para o sistema padrão com diferenças em relação ao fornecido pelo laboratório primário entre 1,3% e 15,3%. Os resultados obtidos indicaram a viabilidade do estabelecimento deste protocolo de calibração utilizando a espectrometria como padrão de referência, com incertezas relativas de 0,62% para k=1. As incertezas associadas ao método proposto foram satisfatórias, para um laboratório padrão secundário e comparáveis a um laboratório primário.<br>Tese (Doutorado em Tecnologia Nuclear)<br>IPEN/T<br>Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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Крочак, Валентин Ігорович, та Valentyn Krochak. "Метод розпізнавання імпульсів іонізуючого випромінювання для підвищення інформативності радіометричних вимірювань". Master's thesis, Тернопільський національний технічний університет імені Івана Пулюя, 2020. http://elartu.tntu.edu.ua/handle/lib/33246.
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В кваліфікаційній роботі розроблено метод розпізнавання імпульсів іонізуючого випромінювання для задачі підвищення інформативності іонізаційного методу радіометричних вимірювань. Проаналізовано відомі методи вимірювання радіоактивності та встановлено, що іонізаційний метод вимірювання радіоактивності з застосуванням давачів Гейгера-Мюллера є дешевим та простим, але недостатньо інформативним. Розроблений метод відрізняється підвищеною інформативністю та точністю. За допомогою введення давача Гейгера-Мюллера в обмежений пропорційний режим роботи, вдалось виявити нові інформативні ознаки у імпульсах на його виході. В якості інформативних ознак запропоновано використовувати відмінності у спектральній густині потужності імпульсів.<br>СПИСОК СКОРОЧЕНЬ8 ВСТУП 9 РОЗДІЛ 1. АНАЛІТИЧНА ЧАСТИНА 12 1.1. Основні види іонізуючого випромінювання 12 1.2. Методи реєстрації іонізуючого випромінювання14 1.3. Особливості іонізаційного методу реєстрації іонізуючого випромінювання17 1.3.1. Основні принципи роботи і конструкція давачів Гейгера-Мюллера22 1.3.2. Виявлення нейтронів за допомогою давача Гейгера-Мюллера 26 1.3.3. Пропорційні лічильники 26 1.4. Висновки до розділу 1 .28 РОЗДІЛ 2. ОСНОВНА ЧАСТИНА 29 2.1. Оцінка іонізуючого випромінювання як випадкового процесу29 2.2. Характеристика сигналу на виході радіометричної установки33 2.3. Висновки до розділу 2 42 РОЗДІЛ 3. НАУКОВО-ДОСЛІДНА ЧАСТИНА 43 3.1. Оцінка впливів на давач Гейгера-Мюллера 43 3.2. Експериментальна установка та режим роботи давача Гейгера-Мюллера 44 3.3. Оцінка окремих імпульсів на виході радіометричної установки 50 3.4. Висновки до розділу 3 57 РОЗДІЛ 4. ОХОРОНА ПРАЦІ ТА БЕЗПЕКА В НАДЗВИЧАЙНИХ СИТУАЦІЯХ 58 4.1. Безпека в надзвичайних ситуаціях 58 7 4.1.1. Мета забезпечення єдності вимірювань характеристик іонізуючих випромінювань 58 4.1.2. Порядок виконання заходів щодо забезпечення єдності вимірювань характеристик іонізуючих випромінювань і ядерних констант 60 4.1.3. Заходи метрологічного забезпечення в єдиній державній системі цивільного захисту63 4.2. Охорона праці 66 4.3. Висновки до розділу 4 69 ЗАГАЛЬНІ ВИСНОВКИ .70 ПЕРЕЛІК ПОСИЛАНЬ 72 Додаток А. Параметри основних видів іонізуючого випромінювання 75 Додаток Б. Копія тези конференції 76
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Stopka, Sylwia Anna. "New Ionization Methods for the Analysis and Imaging of Microbial Populations and Biological Tissues by Mass Spectrometry." Thesis, The George Washington University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10686696.
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<p> To evaluate the complex and diverse biochemical processes within organisms, continued advances in chemical analysis are needed for the rapid detection, identification and quantitation of biomolecules. Due to its exquisite sensitivity and specificity, mass spectrometry (MS) based methods have become an indispensable tool for the analysis and spatial mapping of metabolites, lipids, peptides, and xenobiotics. This dissertation describes my efforts in advancing the analysis of biological samples, cell populations, and tissue sections using MS-based methods based on direct laser sampling and photonic nanostructures. </p><p> Chapter 1 provides background information on well established and emerging ambient and laser desorption ionization mass spectrometric methods for the analysis of small molecules. The emphasis is on high-throughput analysis directly from microorganisms, matrix-free molecular imaging from biological tissue sections, and enhancement of ionization by matrix-free nanostructure arrays. </p><p> Chapter 2 describes using laser ablation electrospray ionization with ion mobility separation (LAESI-IMS)-MS as a high-throughput method for the metabolic and lipidomic profiling of genetically modified algae, as well as for exploring environmental perturbations for increased lipid production. Benefits of IMS include aiding in lipid classification and identification by assigning unique drift times to lipid classes and to the degree of saturation, as well as helping structure elucidation by IMS linked to tandem-MS. </p><p> Chapter 3 presents pulse-chase analysis in combination with LAESI-IMS-MS to determine metabolite, lipid, and peptide turnover rates directly from algal cell populations. Here IMS was used to help identify the nitrogen isotopologues in which the relaxation of isotope distribution patterns to natural abundances was monitored as a function of time. </p><p> Chapter 4 explores the symbiotically induced metabolites involved in the interaction between legumes and soil rhizobia by LAESI-IMS-MS. By laser ablation sampling, the spatial mapping of biomolecules was demonstrated on whole soybean root nodules by depth profiling through the different anatomical regions of the nodule. </p><p> Chapter 5 demonstrates the feasibility of vacuum-based matrix-free MS imaging by laser desorption ionization (LDI) from silicon nanopost arrays (NAPA)through determining the spatial distributions of biomolecules in biological tissues and small cell populations. The mechanism of ion formation and material removal from thin tissue sections was explored using electron microscopy. </p><p> Chapter 6 introduces a new nanophotonic LDI MS platform, elevated bowtie (EBT) arrays, that exhibits enhanced near-field effects, higher ion intensities, as well as greater control over fragmentation for small molecules and peptides. The effect of the bowtie antenna apex angle on ion production and near-field enhancement was also evaluated. </p><p> Chapter 7 surveys the current state of the MS field for emerging ambient- and vacuum- based ionization technologies with a focus on overcoming their major challenges and providing future improvements. Future directions were explored with emphasis on potential applications of these MS-based technologies. </p><p>
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Nasreddine, Rouba. "Développement d'une méthode analytique et d'un microanalyseur miniaturisé pour la détection des BTEX dans l'air." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAF010.
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Les BTEX est une famille de polluants très répandue en air intérieur. Ils présentent des effets nocifs sur la santé humaine à des faibles concentrations ce qui a emmené le législateur à fixer des seuils afin de limiter l'exposition des gens. L'objectif de ce travail de recherche est de développer et de mettre en place une méthode analytique sensible, précise et rapide basée sur un dispositif de mesure. Le dispositif ainsi mis en place est un chromatographe en phase gazeuse miniaturisé équipé d'un mini détecteur à photo ionisation dédié à la détection des BTEX en temps quasi-réel. Le système analytique est très portable ayant une consommation gazeuse très faible assurant une autonomie élevée sur de longues durées. Son mode de fonctionnement se base sur l'échantillonnage de l'air dans une boucle connecté à une vanne six voies. L'injection de l'échantillon sur une colonne analytique placée dans un four pour la séparation est assurée par le changement de la position de la vanne avant la détection par photo ionisation. Le nouveau dispositif miniaturisé a été déployé lors de deux campagnes intensives menées dans un collège énergétiquement performant. Cette étude a porté sur la surveillance temporelle de la concentration des polluants présents en air intérieur, y compris les BTEX. Les résultats ainsi obtenus pour les BTEX avec notre dispositif ont été comparés à ceux fournis par d'autres techniques dites techniques de référence. Ces campagnes de terrain ont permis donc de valider les performances analytiques, la robustesse et l'autonomie de cette nouvelle méthodologie<br>BTEX are very widespread indoor air pollutants. Their harmful effects on human health had led the legislator to set thresholds in order to limit the population exposure. The aim of this thesis is to develop a sensitive, accurate and fast analytical method based on a measurement device. Therefore, the device implemented is a miniaturized gas chromatography (GC) equipped with a mini photo ionization detector dedicated to BTEX detection in indoor air in near-real time. The miniaturized GC is very portable with a very low gas consumption which enhances its autonomy over a long period. Its operation mode is based on air sampling inside a sample loop which is connected to a six port valve. The injection over a heated analytical column is ensured by switching the valve position before detection by a photo ionization detector. This novel device was used in real conditions during two field campaigns conducted in an energy efficient college. This study focused on the temporal monitoring of indoor air pollutant concentrations including BTEX. The results obtained with our miniaturized device for BTEX were compared to those given by other techniques known as reference techniques. These field campaigns have therefore enabled us to validate the analytical performances, the robustness and the autonomy of this novel analytical method