Dissertations / Theses on the topic 'Two-dimensional gas chromatography'
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Venter, Andre. "Comprehensive two-dimensional supercritical fluid and gas chromatography (SFCxGC)." Thesis, Pretoria : [s.n.], 2003. http://upetd.up.ac.za/thesis/available/etd-03132003-161136.
Full textSong, Shin Miin, and shinmiin@singnet com sg. "Comprehensive two-dimensional gas chromatography (GCxGC ) for drug analysis." RMIT University. Applied Sciences, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080627.114511.
Full textVestner, Jochen. "Application of comprehensive two dimensional gas chromatography to wine analysis." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/18117.
Full textENGLISH ABSTRACT: This study focused on the potential of comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-TOF-MS) for the improved analysis of volatile wine constituents. Solid phase microextraction (SPME) in combination with GC×GC-TOF-MS was successfully used for the detailed investigation of the impact of three commercial Oenococcus oeni lactic acid bacteria (LAB) strains on the volatile composition of Pinotage wines subjected to malolactic fermentation (MLF). Due to increased separation power and enhanced sensitivity obtained by using two orthogonal separations coupled with the structural information provided by deconvoluted TOF-MS spectra, GC×GC-TOF-MS allowed for the identification and semi-quantitative analysis of much larger numbers of compounds compared to previous studies applying one-dimensional gas chromatography. The combination of univariate and multivariate statistical assessment was used as a powerful tool for data interpretation. The obtained results contribute significantly to the understanding of the impact of MLF on the volatile composition of Pinotage wine Some compounds have been linked to MLF for the first time. Moreover, the impact of these commercial starter cultures on the composition of volatile sulfur and nitrogen compounds in the same wines was studied by one-dimensional gas chromatographic methods with headspace injection and solid supported liquid-liquid extraction together with sulfur selective detection and tandem mass spectrometry. This study demonstrated also for the time, the impact of MLF on the composition of volatile sulfur and nitrogen compounds in Pinotage wine. GC×GC-TOF-MS was further used for the evaluation of the suitability of a new phase for stir bar sorptive extraction (SBSE) analysis of wine volatiles. Despite instrumental complications, beneficial extraction properties of the new stir bar phase for especially more polar compounds could be demonstrated. In addition, the extraction ability of this novel phase was evaluated for the analysis of selected thiazoles in wine using heart-cutting two dimensional gas chromatography in combination with nitrogen selective detection. Advantageous extraction performance of the new stir bar phase compared to a conventional polydimethylsiloxane (PDMS) phase for the determined thiazoles was demonstrated.
AFRIKAANSE OPSOMMING: Hierdie studie het gefokus daarop om die potensiaal van omvattende tweedimensionele gaschromatografie gekombineer met vlugtyd massaspektrometrie (GC×GC-TOF-MS) vir die verbeterde analise van vlugtige wynkomponente te ondersoek. Soliede fase mikro-ekstraksie (SPME) in kombinasie met GC×GC TOF MS is met sukses aangewend vir ‘n ondersoek na die impak van drie kommersiële Oenococcus oeni melksuur bakteria (LAB) rasse op die samestelling van die vlugtige fraksie van Pinotage wyne wat appelmelksuurgisting (AMG) ondergaan het. As gevolg van die verbeterde skeidingsvermoë en die verhoogte sensitiwiteit wat verkry word deur twee ortogonale skeidings te kombineer, tesame met die inligting aangaande die molekulêre struktuur wat die die gedekonvoleerde TOF massaspektra verskaf, maak GC×GC-TOF-MS die identifikasie en semi-kwantitatiewe analise van aansienlik meer komponente, in vergelyking met die gebruik van een-dimensionele gaschromatografie, moontlik. Die kombinasie van monoveranderlike asook multiveranderlike statistiese evaluering is gebruik as ‘n kragtige tegniek vir data interpretasie. Die resultate wat verkry is dra tot ‘n groot mate by tot die ontrafeling en begrip aangaande die impak wat AMG op die samestelling van vlugtige komponente in Pinotage wyn het. Daar word ook vir die eerste keer aangetoon dat somminge komponente verband te hou met AMG. Aanvullend hiertoe is die impak wat hierdie kommersiële kulture (wat gebruik word om fermentasie te inisieer) op die voorkoms van swawel en stikstof bevattende vlugtige komponente het bestudeer deur gebruik te maak van een-dimensionele gaschromatografiese metodes met ‘headspace’ inspuiting en vloeistof-voeistof ekstraksie tesame met swawel en stikstof selektiewe deteksie en tandem massaspektrometrie. Hierdie ondersoek werp lig, ook vir die eerste keer, op die samestelling van vlugtige swawel en stikstof bevattende komponente in Pinotage wyn. GC×GC-TOF-MS is ook gebruik vir die evalueering van die toepaslikheid van ‘n nuwe stasionêre fase vir gebruik met roerstaaf sorptiewe ekstraksie (SBSE) vir die analisering van vlugtige komponente in wyn. Ten spyte van instrumentele komplikasies, is die voordele wat hierdie nuwe fase vir die ekstraksie van vernaamlik meer polêre komponete aangetoon. Vervolgens is die ekstraksievermoë van hierdie nuwe fase vir die analise van sekere tiasole in wyn met ‘heart-cutting’ twedimensionaly gaschromatografie in kombinasie met stikstof-selektiewe deteksie gedemonstreer. Verbeterde ekstraksie van die nuwe roerstaaf fase vir die analise van tiasole, in vergelyking met ‘n tradisionele polydimethylsiloxane (PDMS) fase is voorts aangetoon.
Dunmore, Rachel. "Characterisation of urban and remote atmospheres using comprehensive two dimensional gas chromatography." Thesis, University of York, 2015. http://etheses.whiterose.ac.uk/11956/.
Full textFraga, Carlos Gerardo. "Comprehensive two-dimensional gas chromatography and chemometrics for the analysis of complex mixtures /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/8690.
Full textSamiveloo, Silverraji Chemistry Faculty of Science UNSW. "High speed comprehensive two-dimenstional gas chromatography/mass spectrometry." Awarded by:University of New South Wales, 2005. http://handle.unsw.edu.au/1959.4/39732.
Full textSinha, Amanda E. M. "Comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry with chemometric analysis /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/8566.
Full textHarju, Mikael. "Analysis of PCBs with special emphasis on comprehensive two-dimensional gas chromatography of atropisomers." Doctoral thesis, Umeå universitet, Kemi, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-54.
Full textEgeness, Mari Jystad. "Comprehensive Two-Dimensional Gas Chromatography: method development and verification by characterisation of petroleum fractions." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for kjemi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16799.
Full textWang, Min. "Novel applications of comprehensive two-dimensional gas chromatography and capillary electrophoresis for the chiral discrimination." HKBU Institutional Repository, 2007. http://repository.hkbu.edu.hk/etd_ra/823.
Full textGrobler, Thelma. "Two-dimensional gas chromatography : a novel technique for iron low temperature Fischer-Tropsch selectivity studies." Master's thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/5327.
Full textIncludes bibliographical references (leaves 158-178).
Fischer-Tropsch synthesis is a process that catalytically converts hydrogen and carbon monoxide into a large variety of hydrocarbons and oxygenated products. Over the years many researchers have attempted to describe the full product spectrum (ranging from C1 to C100+) but due to the complexity of the product and shortcomings of certain analytical techniques (or equipment) most researchers were only able to construct product distributions from extrapolations of data recorded from analysis of the C1 to C5 fraction of the Fischer-Tropsch product. With recent advances in analytical technology and the development of comprehensive two-dimensional gas chromatography (GCxGC) it may now be possible to analyze the complex Fischer-Tropsch products in a relatively short time while delivering good separation of even minor compounds such as oxygenates and branched compounds. The aim of this study was to investigate if two-dimensional gas chromatography (GCxGC) really results in improved separation and identification of compounds in the complex Fischer-Tropsch product spectrum and will lead to a more complete product distribution especially of the minor compounds such as branched hydrocarbons, ketones, aldehydes and acids. For this study GCxGC equipment, supplied by Zoex Corporation, was connected to a micro slurry phase reactor system to provide for both on-line gas analysis as well as off-line product analysis. GCxGC methods were developed to analyze the hot tail gas and oil products from Fischer-Tropsch synthesis. Thereafter a test sample (C6 to C30 oil product from Fischer- Tropsch synthesis process) was injected several times into both the GCxGC and 1D GC systems. The purpose of this was to compare the detection ability and accuracy of the two instruments.
Lidster, Richard T. "Development of comprehensive two-dimensional gas chromatography for the analysis of volatile organic compounds in the atmosphere." Thesis, University of York, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.583259.
Full textGallacher, Christopher. "Environmental forensics of coal tar using two dimensional gas chromatography time-of-flight mass spectrometry (GCxGC-TOFMS)." Thesis, University of Strathclyde, 2016. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=27887.
Full textMohler, Rachel E. "Discovery based yeast metabolomic analysis using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry and chemometrics /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/11578.
Full textLiu, Jiayi. "Development and Applications of Functionalized Octatetrayne as Novel Carbon Media in Chromatography." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1519322396476316.
Full textDanielsson, Conny. "Trace analysis of dioxins and dioxin-like PCBs using comprehensive two-dimensional gas chromatography with electron capture detection." Doctoral thesis, Umeå universitet, Kemiska institutionen, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-963.
Full textDanielsson, Conny. "Trace analysis of dioxins and dioxin-like PCBs using comprehensive two-dimensional gas chromatography with electron capture detection /." Umeå : Department of Chemistry, Environmental Chemistry, Umeå University, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-963.
Full textFidelis, Carlos Henrique de Vasconcelos. "Desenvolvimento de um sistema para cromatografia gasosa bidimensional compreensiva." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250207.
Full textTese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
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Resumo: O projeto objetivou estudar os fundamentos que governam um sistema GC×GC, por meio da construção do principal componente de tal sistema, o modulador, sua adaptação a um cromatógrafo a gás comercial e posterior aplicação. O ponto de partida do desenvolvimento instrumental foi a projeção e a construção de um modulador de duplo jato com dois cabeçotes de aço e dióxido de carbono líquido como agente crioscópico. Numa segunda etapa os dois cabeçotes foram substituídos por peça única, utilizando-se ainda o mesmo fluido para resfriamento. Posteriormente o modelo em peça única foi alimentado por nitrogênio líquido. Ambos os sistemas moduladores foram controlados por softwares escritos em laboratório. O primeiro, utilizado em testes iniciais, foi escrito em Visual Basic 3. Em um segundo momento, foi escrito simultaneamente ao desenvolvimento do modulador um software exclusivo para o controle da modulação e registro dos dados. Durante todo o trabalho, algumas aplicações foram feitas para testar o desempenho do sistema. Foram realizadas separações GC×GC principalmente de amostras de gasolina Tipo C. Os resultados obtidos foram extremamente promissores uma vez que ficou demonstrada a aplicabilidade de um sistema modulador para GC×GC utilizandose um forno secundário, externo ao forno do cromatógrafo
Abstract: The aim of this project was to investigate the basic concepts concerning a GC×GC system by adjusting the main system component, the modulator, to a commercial gas chromatograph and its subsequent application. The instrumental development starting point was the projection and construction of a two piece dual jet modulator with carbon dioxide as coolant. In a second stage the two nozzles were replaced by a single piece and the same coolant was used. In sequence nitrogen gas cooled by liquid nitrogen was used as modulating agent with the single piece design. For system control and data acquisition two homemade software were used. The first was written in Visual Basic 3. The second was developed simultaneously to the modulator and is an exclusively applied version. During project development some applications were showed to evaluate system performance. GC×GC separations were performed mainly by using Brazilian gasoline C type. The results obtained are very promising once was demonstrated the applicability of a modulator system using a secondary oven external to the chromatograph oven
Doutorado
Quimica Analitica
Doutor em Ciências
Roskamp, Melissa Jordan. "Characterization of Secondary Organic Aerosol Precursors Using Two-Dimensional Gas Chromatography with Time of Flight Mass Spectrometry (GC×GC/TOFMS)." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/1411.
Full textHan, Ung Bin. "Characterization of chemical markers for the discrimination of East Asian handmade papers using pyrolysis, gas chromatography and mass spectrometry." Thesis, Paris, Muséum national d'histoire naturelle, 2018. http://www.theses.fr/2018MNHN0005/document.
Full textThis study was conducted to explore a new methodology for handmade fiber characterizationand identification using pyrolysis, gas chromatography and mass spectrometry. It employseasy sampling process with minor quantity of samples required. After pyrolysis of handmadepapers, a featured metabolites distribution patterns (presence plus intensity) eluting in the defined region of interest (ROI) was observed to be characteristic for handmade papers of different material origins. The method utilizes these metabolites distribution patterns as markers to discriminate different fiber origins. Firstly, the problems encountered in the investigation of handmade papers were introduced such as the origin of papermaking, the inconsistency in the fiber identification results sometimes gained by different scholars, the limits of microscopy in identifying fibers from similar species and the likely imprecision of the reference sample labeling. All these problems showed the necessity to explore a new method in order to (i) make precise fiber identification of handmade papers and (ii) to validate or confirm the identification results obtained by microscopy. Then, modern reference handmade papers were firstly studied. The result revealed that different plant fibers used for papermaking have different marker distributions in the ROI, forinstance, the Moraceae family with a featured distribution of terpene compounds and theThymelaeaceae family with a featured distribution of stigmasta compounds. The fibers fromthe ma group usually revealed few compounds in the ROI. This metabolites difference in theROI was attested from the plant tissues with their similar distribution in handmade papers and plant raw fibers. Thus, the chosen methodology offers promise as a method of chemotaxonomy for unknown handmade paper fiber identification. With the examples ofapplications provided during the experimental work, the coupling of pyrolysis, gaschromatography and mass spectrometry (through the use of Py-GC/MS and Py-GCxGC/MS)showed its ability to distinguish fibers from the same plant family (that may present similar microscopic features) and thus, can constitutes an effective method for fiber identification as well as to validate the identification results of the microscopic observation. In the present thesis, the features of GCxGC and the benefits for cultural heritage applications and its help for the ID data treatment were discussed. The tested Py-GCxGC/MS methodology has been for the first time proposed in the cultural heritage field and it harbors the potential to promote the research in this domain, enhancing our capacity to handle small quantities of complex samples while providing an exhaustive response on its composition
Megson, David Peter. "Application of polychlorinated biphenyl signatures for environmental fingerprinting." Thesis, University of Plymouth, 2014. http://hdl.handle.net/10026.1/3135.
Full textAlmstetter, Martin F. [Verfasser], and Frank-Michael [Akademischer Betreuer] Matysik. "Tools and applications for one- and two-dimensional gas chromatography – time-of-flight mass spectrometry-based metabolomics / Martin F. Almstetter. Betreuer: Frank-Michael Matysik." Regensburg : Universitätsbibliothek Regensburg, 2012. http://d-nb.info/1023312379/34.
Full textGodoy, Junior Luiz Antonio Fonseca de. "Emprego de métodos quimiométricos em análises por cromatografia gasosa bidimensional abrangente." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249332.
Full textTese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
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Resumo: Nesta tese, foram construídos modelos quimiométricos a partir de cromatogramas de diferentes amostras obtidos por cromatografia gasosa bidimensional abrangente com detecção por ionização em chama (GC×GC-FID). Numa primeira aplicação, modelos foram desenvolvidos para identificar adulteração em gasolina. Para isso, uma amostra de gasolina não adulterada fornecida pela Agência Natural do Petróleo (ANP) foi utilizada na preparação de um conjunto de calibração e de um conjunto de validação de amostras de gasolinas adulteradas. Em seguida, o modelo construído foi utilizado para avaliar outras amostras de gasolinas e os resultados obtidos foram comparados com os resultados obtidos pela ANP. Em um segundo estudo com gasolinas, 51 amostras foram fornecidas pela ANP juntamente com os resultados dos testes físico-químicos utilizados pela agência na avaliação da qualidade da gasolina. O objetivo deste estudo foi a elaboração de modelos quimiométricos utilizando dados de GC×GC-FID para a previsão de parâmetros físico-químicos de gasolina. Os métodos de seleção de variáveis siPLS e algoritmo genético foram utilizados na preparação de modelos para a previsão da temperatura de destilação a 10, 50 e 90 % v/v de destilado e no ponto final da destilação. Um modelo PLS foi construído para a previsão da densidade das amostras de gasolinas. Em um terceiro estudo, utilizando PARAFAC e GC×GC-FID, foi realizada a diferenciação entre amostras de gasolina do Brasil e da Venezuela, devido ao intenso contrabando de gasolina existente da Venezuela para o Brasil. Em uma quarta aplicação, foi desenvolvido um algoritmo para seleção de intervalos em dados de ordem superior, o qual foi avaliado através da quantificação de alergênicos em perfumes. Por último, foi relatado o primeiro uso de MCR-ALS na construção de modelos quimiométricos utilizando-se dados obtidos por GC×GC-FID para quantificação de óleo essencial de alecrim em amostras complexas preparadas em laboratório
Abstract: In this thesis, some chemometric models were built using chromatograms of different kinds of samples obtained by comprehensive two-dimensional gas chromatography with flame ionization detection (GC×GC-FID). In the first application, models were developed to identify adulteration in commercial gasoline samples. A non-adulterated gasoline sample provided by the Agência Nacional do Petróleo (ANP) was used to build a calibration and a validation sample set of adulterated gasoline. Then, the built model was used to evaluate other gasoline samples and the obtained results were compared to the results obtained by ANP. In a second study with gasoline, 51 samples were supplied by ANP with the results of the physicochemical tests used by ANP to evaluate the quality of gasoline samples. The aim of this study was the elaboration of chemometric models using GC×GC-FID chromatograms to preview some of the physicochemical tests used by ANP. The variable selection siPLS and genetic algorithm methods were used to build multivariate models in order to preview the distillation temperatures of gasoline at 10, 50 and 90 % v/v of distillated and at the final point of the distillation. A PLS model was built to predict the density of the gasoline samples. In a third study, using PARAFAC and GC×GC-FID, it was performed the differentiation between Brazilian and Venezuelan gasoline, due to the intense smuggling of gasoline from Venezuela to Brazil. In a fourth application, an algorithm was developed for variable selection in multi-way data, which was evaluated by quantification of allergens in perfume. Finally, it was reported the first use of MCR-ALS algorithm to develop chemometric models using data obtained by GC×GC-FID to quantify rosemary essential oil in complex samples prepared in laboratory
Doutorado
Quimica Analitica
Doutor em Ciências
Hantao, Leandro Wang 1986. "Microextração em fase sólida e cromatografia gasosa bidimensional abrangente = aplicações em lipidômica." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250193.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: Neste trabalho foram desenvolvidas metodologias para a análise de lipídios na forma de seus ésteres metílicos de ácido graxo (FAME) em diversas matrizes. Para isso foram empregadas e otimizadas de forma multivariada técnicas de derivatização dos lipídios por transesterificação por catálise básica, seu isolamento e concentração por Microextração em Fase Sólida (SPME) e análise por Cromatografia Gasosa Bidimensional Abrangente (GCxGC). A partir do perfil de extração foi escolhida a fibra comercial com revestimento de poli(dimetilsiloxano) (PDMS) com espessura de filme de 7 mm. O tempo de extração escolhido foi de 10 min pois atingiu a condição de sistema estacionário. Os parâmetros cromatográficos, tais como a programação de temperatura do forno, período de modulação e tipo de fase estacionária das colunas utilizadas no protótipo GCxGC, foram também otimizados. Além disso, durante o progresso deste trabalho, foi desenvolvido o primeiro protótipo brasileiro de GCxGC acoplado a um Espectrômetro de Massas com Analizador Quadrupolar rápido (GCxGCxqMS). Dentre os parâmetros operacionais do qMS, foram otimizados o intervalo de varredura do analizador quadrupolar e sua frequencia de aquisição. O sistema GCxGCxqMS foi empregado para a identificação dos FAME presentes nas amostras empregadas neste estudo, através do uso das informações obtidas pelos espectros de massas obtidos das amostras, com padrões analíticos e combinando o uso de índices de retenção (LTPRI) e da estrutura cromatográfica. Neste trabalho, devido ao incremento em detectabilidade e sensibilidade, foi possível observar diversos FAME comumente não detectados por Cromatografia Gasosa Convencional (GC), como FAME de comprimento ímpar de cadeia e a presença de agrupamento metila no carbono 2 (-br2). Além disso, em virtude da baixa abrangência do banco de dados disponíveis, foi possível, e necessário, criar um banco de dados com índices de retenção para análise de lipídios. Espera-se que estas metodologias desenvolvidas e os resultados apresentados possam ser empregados como ferramenta em estudos de lipidômica e aplicações correlatas
Abstract: The aim of this project was to develop alternative methodologies for lipidomic studies and related applications. A method for the analysis of lipids in different samples such as waxes, edible oils and cheek cells was developed. The isolation and concentration of the analytes was performed by Solid Phase Microextraction (SPME) combined with Comprehensive Two-dimensional Gas Chromatography (GCxGC). Firstly, the base-catalysed transesterification of the lipids into their respective fatty acid methyl esters (FAME) was optimized according to a multivariate model. Thus, the sample prepation was optimized considering the thickness of the coating and their respective extraction profiles. The choosen commercial coating was a poly(dimethylsiloxane) (PDMS) with 7 mm film thickness, the extraction time was 10 min where stationary state conditions were achieved. Secondly, chromatographic parameters were also optimized, such as the temperature programming, modulation period, the identity of the first and second dimensional columns used in GCxGC prototype. During the current study, the first brazillian prototype of a GCxGC coupled to a mass spectrometer with a rapid quadrupolar analyzer was developed (GCxGCxqMS). Also, the scan interval and acquisition frequency of the qMS were optimized. For the identification of the analytes similarity searches for mass spectra, analytical standards and the combination retention indexes with chromatographic structuration were used. Additionally it was possible to detected and identify FAME which couldn't be detected by conventional GC such as odd numbered chain length and branched FAME. Moreover, elution pattern of a branched FAME was reported, specifically the FAME with a methyl group in the carbon 2 (-br2). Because of the restricted content of the retention indexes and mass spectra database, the construction of a database with retention indexes for lipid analysis was built. Hence the ultimate goal of the current study is to present the potencial and applicability of SPME for lipidomic studies and related applications
Mestrado
Quimica Analitica
Mestre em Química
Pérez-Vásquez, Naira. "Contribution au profilage des acides organiques urinaires, chez l'enfant." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112054/document.
Full textAmong inherited metabolic diseases, organic acidemia (OA) or organic aciduria is characterized by urinary excretion of abnormal amounts or types of organic acids. OA is mostly associated with genetic conditions resulting in a specific step of amino acid catabolism dysfunction. Such alterations can produce disease states that range from mild to lethal neurological involvement. Gas chromatography coupled to mass spectrometry (GC-MS) remains the most used analytical technique for detecting specific urinary organic metabolites related to OA. However, after analyzing more than 1,000 urine samples collected from children with neurological disorders, by this technique less than 0.5% of them were positive. Thus, the discovery of new biomarker candidates for other metabolic diseases is urgently needed. The main objective of this thesis was to evaluate a new method using two-dimensional gas chromatography coupled to mass spectrometry (GCxGC-MS) for the both qualitative and quantitative metabolic profiling of children’s urine. As compared to GC-MS, GCxGC-MS shows great resolution power and high peak capacity. For this purpose, we first developed a GCxGC-MS method with an appropriate sample preparation protocol for urinary organic acids profiling. Applied to urine samples of healthy children and children with neurological disorders, the proposed method showed high sensitivity and peak capacity thus opening new possibilities for the characterization of new biomarker candidates. For instance, by this technique, we were able to detect in urines samples more than ninety additional compounds, which are not detected by a conventional GC-MS method. However, taken together the obtained results show that while the GCxGC technique has unmatched power to separate compounds in a complex mixture, the sample preparation protocol remains a limiting step for the precise quantification of the detected compounds. On another hand, in order to reduce the sample preparation step, we evaluated the direct analysis in real time (DART) method for the urinary organic acids screening. The obtained results are very promising
Bártová, Adéla. "Analýza těkavých organických látek produkovaných monocyty během sepse." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2019. http://www.nusl.cz/ntk/nusl-401942.
Full textBoris, Alexandra Jeanne. "Toward the Complete Characterization of Atmospheric Organic Particulate Matter: Derivatization and Two-Dimensional Comprehensive Gas Chromatography/Time of Flight Mass Spectrometry as a Method for the Determination of Carboxylic Acids." PDXScholar, 2012. https://pdxscholar.library.pdx.edu/open_access_etds/544.
Full textCuzuel, Vincent. "Développement d'une stratégie de caractérisation chimique de la signature odorante d'individus par l'analyse chimiométrique de données issues de méthodes séparatives multidimensionnelles." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066206/document.
Full textCharacterizing human odor is of particular interest in forensic science. Dogs can find a person using their odor-print, but cannot testify : the information they bring lacks probative value in the courts of justice. Thus, developing a whole analytical strategy, from sampling to analysis and data processing, may support the identification dogs provide. After reviewing the studies that have already worked on the subject, the use of dogs in the police force is developed and some aspects of biometrics are presented to know to if the odor can be used as a biometric trait. Innovative, simple and reliable methods were developed to sample odor, either directly on the subject or indirectly at the scene of the crime. Particular attention is paid to the real samples and their conservation. The ability of analytical techniques to separate and identify different constituents of human odor was assessed. Thus, we have developed an analytical method in two-dimensional gas chromatography integral coupled with mass spectrometry. The performance of several sets of columns was compared by considering nine of the criteria most used in the literature. Finally, we established a representative panel on which we were able to apply statistical approaches for the comparison of samples
Braga, Soraia Cristina Gonzaga Neves 1986. "Determinação de off-flavours em carne e gordura suína por GCxGC combinada a SPME." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250188.
Full textDissertação ( mestrado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: A carne de porco é a proteina mais consumida no mundo. Para ser consumida a carne necessita de um padrão de qualidade e um dos problemas que afeta esta qualidade é o surgimento de odores desagradáveis. Estes odores, conhecidos como boar taint, são causados principalmente pela presença de androstenona e escatol em níveis maiores que 1,00 mg g e 0,25 mg g, respectivamente, em gordura suína. Os métodos existentes para determinação destes compostos são dispendiosos e não geram resultados em tempos satisfatórios para análise de rotina. Neste trabalho foi proposto um novo método para determinação de androstenona e escatol em gordura suína que se baseia na utilização de microextração em fase sólida (SPME) e cromatografia gasosa bidimensional abrangente (GC xGC). Para isso foi realizada uma otimização univariada do tipo de fibra e agente saponificante e posteriormente uma otimização multivariada, envolvendo concentração de saponificante, tempo de saponificação, temperatura e tempo de extração. O método otimizado foi validado sob os parâmetros de limites de detecção e quantificação, linearidade, precisão e exatidão. Para o escatol é possível a quantificação de amostras com quantidades menores que as detectadas sensorialmente (0,25 mg g), com precisão e exatidão, mas para a androstenona, é possível apenas detectar a presença ou não deste analito. Após todo o desenvolvimento e validação do método, este foi aplicado em sete amostras de toucinho cedidas pelo ITAL
Abstract: Pork is the must consumed protein the world. For consumpted, the meat needs a quality standard and one of the problems concerning the quality of pork meat are off-flavours. These off-flavores, called boar taint are caused by the presence of two compounds, skatole and androstenone, in levels superior to 1.00 and 0.25 mg g, respectively in pig fat. In order to determine these flavors is necessary to know the concentrations of androstenone and skatole in pig fat. There are specific methods to analyse these compounds, but they spend a lot of time and require a great number of clean-up steps process. In this work, a faster and cleaner method was proposed to determine the presence of androstenone and skatole in pig fat, based in the solid phase microextraction (SPME) and comprehensive bidimensional gas chromatography (GC xGC). A univariate optimization considering the kind of fibre coating and hydrolysis agent was performed. Later a multivariate optimization was developed to determine the concentration of hydrolysis agent, time of saponification and temperature and time of extraction. The best conditions found for the method were used for its validation. The quantification and detection limits, linearity, accuracy and precision were determined. For skatole it is possible to quantify samples at smaller quantities than those found sensorially (0.25 mg g), with precision and accuracy, but for androstenone the method only detects its presence or absence in the analyte. After all the development and validation of the method, it was implemented with seven samples of pig fat, courtesy of ITAL (Instituto de Tecnologia de Alimentos)
Mestrado
Quimica Analitica
Mestra em Química
Hantao, Leandro Wang 1986. "Aplicação de métodos quimiométricos na investigação do metaboloma de eucalipto por técnicas cromatográficas multidimensionais e hifenadas à espectrometria de massas." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250199.
Full textTese (doutorado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: O presente trabalho é dedicado à aplicação de técnicas cromatográficas multidimensionais à problemas complexos de separação. No primeiro conjunto de estudos foram desenvolvidos métodos analíticos para investigação do metaboloma de plantas de interesse comercial. Para isso, foram utilizadas a cromatografia gasosa bidimensional abrangente (GC×GC-MS) e a cromatografia líquida de ultra eficiência (UHPLC-MS) acopladas à espectrometria de massas para aquisição do perfil metabólico de folhas de eucalipto. Logo, foram desenvolvidos modelos quimiométricos para interpretação dos dados e determinação de marcadores biológicos associados ao estresse biótico e ao fenômeno de resistência. Estes estudos permitiram aprimorar o entendimento do mecanismo de defesa de eucaliptos contra fitopatógenos. Em segundo plano, foram desenvolvidas fases estacionárias derivadas de líquidos iônicos (IL) para separação de compostos apolares por GC×GC. Para isso, foram sintetizados diversos IL derivados de fosfônio e imidazólio. A partir destes materiais foram preparadas colunas capilares pelo método estático de revestimento. Estas colunas de GC foram utilizadas na separação de analitos modelo (i.e., hidrocarbonetos alifáticos) por GC×GC. Estes ensaios visaram aprimorar o entendimento da relação entre as características estruturais dos IL e os mecanismos que governam a retenção de compostos apolares pelas fases derivadas de IL
Abstract: In the present dissertation, we discuss the application of multidimensional chromatographic techniques to solve complex problems. In the first chapter it is presented the development of chemometric strategies for data processing of metabolic data ¿ the current bottleneck of a metabolomics workflow. The case studies examined investigate the metabolome of eucalyptus leaves to address several growing concern in plant pathology, namely, prospection of orthogonal methods for early diagnosis diseases and selection of hybrids with specific phenotypes in genetic enhancement programs. To accomplish these goals, comprehensive two-dimensional gas chromatography coupled to mass spectrometry (GC×GC-MS) and ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) were examined to generate unbiased and reliable metabolic profiles. From these experiments, it was possible to improve our understanding of the defense mechanism of plants. The second chapter addresses the limited availability of stationary phases for multidimensional gas chromatography. In this work, we evaluated ionic liquids as stationary phases for gas-liquid chromatography. The model analytes were nonpolar aliphatic hydrocarbons due to the aggravated lack of highly selective and thermally stable GC columns for their separation. From these experiments, we ascertained the structure-selectivity relationship of ILs and were able to improve our understanding on the retention of nonpolar analytes by IL-based GC columns
Doutorado
Quimica Analitica
Doutor em Ciências
Hamalčíková, Veronika. "Necílený screening organických polutantů ve vodách a sedimentech." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2011. http://www.nusl.cz/ntk/nusl-216788.
Full textPellattiero, Erika. "Conjugated Linoleic Acid (CLA) content in different tissues of ruminants fed with CLA supplementation." Doctoral thesis, Università degli studi di Padova, 2014. http://hdl.handle.net/11577/3424589.
Full textDal 1987 anno in cui il Dott. Pariza e il suo gruppo di ricerca scoprirono i Coniugati dell’Acido Linoleico (CLA) molti sono stati gli studi che hanno cercato di definire le principali caratteristiche di queste molecole. Caratterizzati da un alto valore biologico gli furono attribuiti molti effetti benefici sulla salute umana, come l’effetto anticancerogeno, la riduzione del rischio di malattie cardiovascolari e la riduzione del rischio di sviluppo dell’aterosclerosi. In seguito gli fu attribuita anche importanza nel miglioramento delle performance animali, come l’aumento delle capacità di accrescimento, dell’efficienza alimentare e una riduzione della deposizione di grasso con conseguente aumento della massa magra. I Coniugati dell’Acido Linoleico (CLA) sono un gruppo d’isomeri geometrici e posizionali dell’Acido Linoleico caratterizzati da una catena di 18 atomi di carbonio contenente due doppi legami non in posizione classica (cis), ma coniugati dal carbonio 9, 10 o 11. I doppi legami possono presentare diversa disposizione spaziale dando origine a quattro diverse configurazioni: cis/trans, trans/cis, cis/cis e trans/trans. Secondo i carboni ai quali sono legati, possono avere diverse posizioni: ([7,9], [8,10], [9,11], [10,12], [11,13] e [12,14]) con un totale d’isomeri identificati pari a 24. I due più presenti e più identificati sono il C18:2cis9,trans11 (60-85% degli isomeri presenti nella carne e >90% nel latte) e il C18:2trans10,cis12. Altri isomeri molto presenti nella carne sono anche il C18:2trans7,cis9 e il C18:2trans11,cis13. Grazie alla capacità del rumine di produrre acidi grassi e in particolare CLA, si possono trovare soprattutto nei prodotti di origine animale (latte, prodotti lattiero caseari e carne). La presenza del doppio legame rende i CLA delle molecole complesse da identificare, perché può essere facilmente soggetto a fenomeni d’isomerizzazione o epimerizzazione che possono portare a un aumento delle forme di tipo trans/trans con conseguente riduzione delle forme cis/trans o trans/cis. Diversi studi hanno cercato di definire quale sia il metodo più adatto per l’estrazione del grasso (determinazione estratto etereo, EE) e per la successiva trasformazione in composti volatili, ovvero, esteri metilici degli acidi grassi (FAME). Per questo motivo parte della mia tesi è stata improntata su un approccio metodologico allo scopo di capire tra i tanti metodi quale fosse il più idoneo e che differenze i diversi metodi potessero avere. I dati contenuti nei contributi legati all’approccio metodologico sono stati raccolti da vitelloni maschi nati da un incrocio tra vacche da latte di razza Bruna e tori di razza Bianca Blu del Belgio. Questi animali sono stati allevati presso l’azienda sperimentale dell’Università degli Studi di Padova Lucio Toniolo. Durante tutta prova sono stati allevati in azienda e alimentati con una dieta a base di unifeed caratterizzata da tre diverse integrazioni di CLA rumino protetti (rpCLA): 0, 8 e 80 g di CLA al giorno per ogni animale. La prova è terminata con la macellazione avvenuta in un macello esterno all’Università situato a Pergine (Provincia di Trento, Trentino Alto Adige). I tessuti utilizzati per le analisi sono stati prelevati in macello ed in laboratorio di Qualità carne durante lo svolgimento delle analisi di qualità. I tessuti prelevati e studiati sono stati tre: muscolo Longissimus Thoracis, grasso sottocutaneo e fegato. Nel primo contributo (Chapter 2) i tessuti (Longissimus Thoracis, grasso sottocutaneo e fegato) sono stati analizzati allo scopo di determinare il profilo acidico, confrontando tre diversi metodi di estrazione del grasso (Folch (1957), Acellerated Solvent Extraction (ASE) e Jenkins (2010)) e utilizzando come tecnica cromatografica la Gas Cromatografia a due dimensioni (GCxGC). La scelta di eseguire un confronto metodologico è legata al fatto che secondo il metodo d’analisi utilizzato i risultati sono diversi. Di conseguenza, uno degli obiettivi era trovare un metodo che fosse in grado di salvaguardare i CLA senza provocare isomerizzazioni. A questo è dovuta la scelta del metodo Folch (1957), uno dei più antichi e più utilizzati in matrici di diversa natura. Nato per essere usato in campioni con grasso molto ricco di fosfolipidi (come il grasso presente nel cervello), lavora a temperatura ambiente utilizzando una miscela di solventi composta da cloroformio:metanolo (2:1, v/v). Il metodo Acellerated Solvent Extraction (ASE) è stato utilizzato allo scopo di confrontare una metodica che lavora con alte temperature e pressioni (120°C e 20 MPa) con una miscela di solventi identica a quella usata nel metodo Folch (1957) (cloroformio:metanolo (2:1, v/v)). Grazie alle caratteristiche positive il metodo ASE, negli ultimi anni si è molto diffuso. Esso è caratterizzato da una maggiore velocità d’estrazione, un ridotto utilizzo di solventi e una minore laboriosità da parte degli operatori. Si pensa che le condizioni (temperatura e pressione) a cui lo strumento lavora possano provocare isomerizzazioni incrementando gli isomeri con configurazione trans/trans. L’ultimo è un metodo diretto che in seguito ad una fase preparativa (di liofilizzazione del campione fatta con lo scopo di rimuovere l’acqua) permette di ottenere gli esteri metilici degli acidi grassi (FAME) da poter analizzare in GCxGC. Questo metodo richiede un’esterificazione di tipo acido-basico. Il lavoro è stato suddiviso in quattro passaggi in modo da: identificare il potere di risoluzione e l’incidenza di picchi non identificati, lo studio delle fonti di variazione, test di Levene per determinare l’omoscedasticità o eteroscedasticità delle varianze e infine degli studi per valutare la correlazione tra metodi. L’incidenza di valori non identificati è legata al numero di picchi osservati, che dipendono dalla sensibilità del metodo e dal tessuto analizzato: fegato, grasso e muscolo (da 0.04 a 0.08, da 0.05 a 0.06 e da 0.05 a 0.12, rispettivamente). La maggiore incidenza di valori nulli è stata osservata nel fegato e in particolare negli acidi grassi a corta/media catena (C8:0 e C10:0) e nel muscolo negli acidi grassi C24:0, C20:1t1t unknown isomers e nei PUFAn3 (C20:3n3, C20:4n3, C22:5n6) sempre con il metodo Jenkins (2010). Tra tutte le fonti di variazione analizzate lo scopo, era considerare le due principali che sono state molto significative (P<0.001) e sono rappresentate dal tessuto, dal metodo e dalla loro interazione. L’effetto della dieta è stato significativo per gli acidi grassi facenti parte dell’integrazione (C18:0, C18:1cis9 e C18:2trans10,cis12). Dai test di Levene è emerso che le varianze sono eteroscedastiche, tranne la dieta che è risultata, omoscedastica. Il passo successivo è stato considerare una tecnica cromatografica alternativa al GCxGC che fosse più specifica per lo studio degli isomeri dei CLA (Chapter 7) Nonostante, il GCxGC abbia un maggiore potere di risoluzione non è in grado di identificare tutti gli isomeri dei CLA, ma solo i due principali (C18:2cis9,trans11 e C18:2trans10,cis12). Per questo motivo sono presenti altre tecniche cromatografiche che permettono un’identificazione più precisa come la cromatografia liquida su colonna d’argento (Ag+HPLC). Il lavoro è stato svolto in collaborazione con il Leibniz Insitute for Farm Animal Biology (Dummerstorf, Germany) e in particolare l’unità di Muscle and Biology Growth. L’obiettivo in questo caso era identificare il maggior numero d’isomeri dei CLA presenti nel campione. I tessuti analizzati erano: muscolo (Longissimus Thoracis), grasso sottocutaneo e fegato. Il grasso (estratto etereo, EE) è stato ottenuto con il metodo Folch (1957) cui è seguita poi un’esterificazione acido-basica. Le analisi statistiche sono state eseguite considerando gli effetti di dieta, tessuto e ripetizione sulla distribuzione degli isomeri. La prima cosa che differenzia questa metodica dal GCxGC è il numero di picchi identificati che sono molto più elevati (13 isomeri). Questo tipo di tecnica premette un’identificazione precisa di molti isomeri dei CLA con un unico problema nell’identificazione dei picchi che si trovano nella regione dei cis/cis (l’ultima a comparire nel cromatogramma), per la quale è difficile identificare l’isomero C18:2cis9,cis11. Dai risultati è emerso che il tessuto è molto significativo (P<0.001) e la distribuzione degli isomeri è tessuto dipendente, con una concentrazione più alta nel grasso. L’effetto della dieta, in particolare quella con integrazione 8.0 g di CLA al giorno, è risultato significativo per gli isomeri principali (C18:2cis9,trans11 e C18:2trans10,cis12). Nella seconda parte della tesi sono state prese in considerazione le fonti di variazione del profilo acidico, come razza, sesso, dieta, ordine di parto, età e tessuto (Chapter 3 e Chapter 4). Gli animali usati in queste prove appartengono a quattro razze ovine Venete: Alpagota, Brogna, Foza e Lamon che presentano diversa condizione di criticità; valutata in base al numero di capi allevati, di maschi arieti utilizzati per gli accoppiamenti e di allevamenti. Al fine di salvaguardare e recuperare queste razze, Veneto Agricoltura, su indicazione della Regione Veneto ha creato l’azienda sperimentale di Villiago, un importante centro di conservazione di queste razze, che mira a produrre nuovi giovani riproduttori (agnelle e montoni) per gli allevatori interessati e a organizzare azioni a sostegno dello sviluppo dell’allevamento. I dati riportati in questa tesi coinvolgono animali che sono stati allevati seguendo un piano di conservazione in-situ che prevedeva la collaborazione tra l’azienda sperimentale di Veneto Agricoltura “Villiago” e l’azienda sperimentale dell’Università di Padova “Lucio Toniolo”. In totale gli animali utilizzati sono stati 115 e sono stati allevati tra Dicembre 2010 e Luglio 2012. Macellati a età diverse, erano considerati appartenenti a tre categorie: 31 agnelli da latte, 36 agnelli leggeri, 24 agnelloni pesanti e 24 pecore. Le tre prove (agnello leggero, agnellone pesante, agnello da latte-pecora) erano caratterizzate da diete diverse. Nella prima prova “agnello leggero” le diete utilizzate erano: pascolo (PAS), fieno e concentrati con integrazione CLA rumino protetti (rpCLA, 8.0 g/d/animale) (CLA+) e dieta con fieno e concentrati senza integrazione di rpCLA (CLA-). Nelle prove “agnellone pesante” e “agnello da latte-pecora” le diete erano composte da concentrati con integrazione rpCLA (8.0 g/d/animale per gli agnelloni pesanti, 12 g/d/animale per le pecore e 4.0 g/d/animale per gli agnelli da latte) (CLA+) e concentrati senza integrazione rpCLA (CLA-). Dai risultati è emerso che diversi fattori possono influenzare il profilo acidico e in particolare dalla prima prova che la dieta può avere un ruolo molto importante (P<0.001). La presenza del pascolo è risultata significativa per molti acidi grassi a catena dispari e catena ramificata (forme iso e anteiso) che tendono a essere meno elevati al pascolo. Il motivo è che con la dieta è possibile alterate il PH ruminale e la flora microbica in esso presente modificando così anche gli acidi grassi che questa può produrre. Il ruolo del pascolo è importante anche per quanto riguarda gli acidi grassi a lunga catena (LC-PUFA). Il pascolo può aumentare gli Ω3 (rispettivamente, PAS=2.70, CLA-=1.46 e CLA+=1.54) riducendo gli Ω6 (rispettivamente, PAS =3.76, CLA-=4.41 e CLA+=4.75) e di conseguenze anche il rapporto Ω6/Ω3. Rispetto alla dieta a base di concentrati con integrazione (CLA+) il pascolo ha portato a un aumento dei CLA (rispettivamente, PAS=0.80, CLA-=0.56 e CLA+=0.71). La dieta si conferma significativa, anche nelle prove “agnellone pesante” e “agnello da latte-pecora” con il confronto tra le diete a base di concentrati (CLA- e CLA+). L’integrazione di rpCLA nella dieta è risultata significativa (P<0.001 e P<0.01) per gli acidi grassi considerati i suoi principali costituenti, per cui il C18:0 e il C18:2trans10,cis12. Gli agnelli da latte hanno presentato dei risultati diversi dagli altri animali, soprattutto in relazione ai CLA. Sono risultati significativi gli isomeri C18:2cis11,trans13 (P<0.01), C18:2cis11,cis13 (P<0.001) e C18:2cis9,cis11 (P<0.001). Il motivo di questa diversa distribuzione è stato attribuito al ruolo del latte di pecora, usato come alimento per gli agnelli e che può aver influito sulla composizione acidica dei loro tessuti. La razza in tutte le prove è stata un effetto che non ha portato a delle differenze significative dal punto di vista statistico, come anche il sesso e l’età di macellazione. Dai contrasti effettuati tra tessuti, è emerso, com’era stato osservato per i vitelloni, che la distribuzione degli acidi grassi è tessuto specifica e può cambiare secondo il tessuto analizzato. Differenze sono evidenti in tutti i tessuti ma in particolare tra i magri e quelli grassi. Il fegato in tutte e prove è stato il tessuto che presenta delle caratteristiche particolari perché caratterizzato da una maggiore quantità di acidi grassi polinsaturi (PUFA) e in particolare da una maggiore quantità di Ω3 e CLA. La diversa composizione di questo tessuto è legata alla composizione in termini di tipologia di lipidi che lo costituiscono e dai processi metabolici ai quali quest’organo partecipa che portano alla produzione, oppure all’assorbimento degli acidi grassi assunti con la dieta (Chapter 3 e Chapter 4). Sempre in animali appartenenti alle razze (Alpagota, Brogna, Foza e Lamon) sono state prese in esame le performance animali ed i vari fattori che le possono influenzare. E’ noto che l’utilizzo di rpCLA può provocare un incremento dell’efficienza alimentare favorendo l’aumento della massa magra con la successiva riduzione di quella grassa. Negli animali in lattazione (vacche, pecore e capre) è dimostrato che l’integrazione di rpCLA può provocare una riduzione nel contenuto di grasso presente nel latte. Nella mia tesi è stato considerato l’effetto della dieta sul latte di pecore (Chapter 5) al fine così di valutare quelle che vengono definite proprietà di qualità del latte espresse in termini di composizione chimica e proprietà di coagulazione (MCPs). Gli animali utilizzati in questa prova sono i medesimi utilizzati per lo studio dei profili acidici delle carni. Dal punto di vista della qualità della carne alla macellazione per cercare di definire se dieta, sesso e razza potessero influire sulle rese di macellazione (Chapter 6). Gli animali usati in questa prova sono i medesimi della prova vista in precedenza, ovvero la prova “agnello leggero”. I risultati ottenuti in questo lavoro sono dei risultati che comprendono solo parte del lavoro che invece comprenderà anche le prove “agnellone pesante” e “agnello-pecora”. Da questo lavoro quello che si vuole esprimere è che gli animali appartenenti a queste razze sono in grado di produrre delle carcasse che presentano caratteristiche ottimali e idonee al mercato alimentare. La caratteristica in più che queste presentano è che le modalità di allevamento, ben lontane da quelle di tipo industriale o più specializzato ci permettono di ottenere un prodotto allevato nel rispetto delle tradizioni e che può far parte di presidi ampiamente riconosciuti come l’Agnello Alpagoto noto per essere un presidio Slow Food.
Persson, Monika. "Chemodiversity and Functions of Monoterpene Hydrocarbons in Conifers." Doctoral thesis, KTH, Chemistry, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3639.
Full textPedroso, Marcio Pozzobon. "Projeto e avaliação de um modulador criogenico para cromatografia gasosa bidimensional abrangente (GC x GC)." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250200.
Full textTese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
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Resumo: O objetivo do trabalho foi projetar e avaliar um modulador criogênico para cromatografia gasosa bidimensional abrangente (GC×GC). O modulador projetado foi baseado no modulador de quatro jatos (dois jatos quentes e dois jatos frios); N2 (g) resfriado em N2 (l) foi utilizado como fluido criogênico e N2 (g) aquecido foi utilizado como gás quente. O modulador foi instalado em um cromatógrafo a gás com detector por ionização em chama (GC-FID). O controle das válvulas solenóides e a digitalização do sinal analógico do FID foram realizados por software escrito em ambiente LabVIEW. Os resultados obtidos com o protótipo GC×GC-FID foram comparados com dados obtidos em um GC×GC-FID comercial. O desempenho de ambos os sistemas pode ser considerado equivalente, levando em consideração eficiência cromatográfica e repetibilidade. O protótipo GC×GC-FID foi empregado na análise de diversas amostras, em especial a fração volátil de polpa de abacaxi fresco e desidratado. Os voláteis foram extraídos por microextração em fase sólida através da extração dinâmica do headspace (DHS-SPME). A identificação dos compostos foi feita por cromatografia gasosa acoplada a espectrometria de massas (GC-MS) e avaliação dos índices de retenção. A identificação dos picos no cromatograma GC×GC foi feita através da comparação dos índices de retenção e dos perfis cromatográficos previamente obtidos por GC-MS. Como esperado, a análise por GC×GC-FID apresentou maior detectabilidade e poder de separação quando comparada com GC-FID. Por fim, alguns compostos não identificados por GC-MS foram identificados através de informação obtida pela estruturação cromatográfica da GC×GC.
Abstract: The aim of this project was to develop and evaluate a cryogenic modulator for comprehensive two-dimensional gas chromatography (GC×GC). The design of the modulator was based on a cryogenic quad jet modulator; N2 (g) cooled with N2 (l) was used as the cryogenic fluid and heated N2 (g) was used as the hot gas. The modulator was fitted into a gas chromatograph equipped with a flame ionization detector (GC-FID). The control of the solenoid valves and digitalization of the analogic FID signal were performed by software written in the LabVIEW platform. Results obtained with the GC×GC-FID prototype were compared with data from a commercial GC×GC-FID system. The performance of both systems was similar regarding chromatographic efficiency and repeatibility. The GC×GC-FID was employed for analysis of several samples, specially volatile organic compounds of fresh and dried pineapple pulp. The analytes were isolated by dynamic headspace solid phase microextraction (D-HSSPME); identification of the compounds was performed by conventional gas chromatography coupled to mass spectrometry (GC-MS) and evaluation of retention indexes. The identification of the peaks on the GC×GC chromatograms was carried out by comparison of retention indexes and chromatographic profiles previously obtained by GC-MS. As expected, the detectivity and separation power of the GC×GC-FID analysis was significantly better than that of GC-FID. Moreover, the identity of some compounds not identified by GC-MS was assigned after information obtained from GC×GC chromatographic structure.
Doutorado
Quimica Analitica
Doutor em Ciências
Silva, Bruno José Gonçalves da. "Desenvolvimento de métodos cromatográficos hifenados (in-tube SPME/LC-FLD e GCxGC/qMS) para análises de fármacos e agrotóxicos em amostras complexas." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/59/59138/tde-10082011-101558/.
Full textDetermination of trace levels of drugs in biological fluids and multiresidue (contaminants) in food samples is extremely important because this generates valuable data for therapeutic drug monitoring (individualization of dosage regimen) and quality control (food safety), respectively. Because of the demand for analytical methods with high resolution and low limits of quantification for analysis of complex samples, analytical chemistry has stimulated the development of innovative approaches, especially those aimed at developing or evaluating new analytical systems. In this context, in the first stage of this thesis the automated solid-phase microextraction capillary polypyrrole (in-tube \"PPY SPME) coupled to liquid chromatography with fluorimetric detection was developed (lab-made) for enantioselective determination of fluoxetine and its metabolite norfluoxetine in plasma samples for therapeutic drug monitoring. In the second stage of this work, the GC x GC / qMS method was developed for multiresidues analysis of pesticides in fresh tomatoes for the purpose of quality control. In the first stage of the research the gain in terms of the selectivity of the polypyrrole extraction phase in hyphenated and automated system for sample preparation and chromatographic separation (LC) with fluorimetric detection is worthy of note. As for the second step, the highlight is the improvement in chromatographic resolution as well as in the detectability system of the system consisting of two-dimensional gas chromatography and spectrometric detection with quadrupole analyzer. Analyses of plasma samples from patients undergoing therapy with fluoxetine and of samples of commercially available tomatoes proved the applicability of the proposed methods, which were optimized and validated at concentrations levels that include the therapeutic range for the analyzed drugs in plasma and the maximum residue limits of pesticides for growing tomatoes.
Ferreira, Ernesto Correa. "Softwares para cromatografia gasosa bidimensional abrangente (GC x GC)." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250202.
Full textTese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
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Resumo: A Cromatografia Gasosa Bidimensional Abrangente (GCxGC) é uma técnica analítica capaz de separar e detectar centenas de picos, sendo aplicada a diferentes amostras petroquímicas, ambientais e biológicas. Esta técnica se diferencia da Cromatografia Gasosa (GC) pela utilização de duas colunas cromatográficas de composições e dimensões diferentes conectadas em série e de uma interface para a coleta das frações da primeira coluna e para a reinjeção na segunda em períodos regulares, denominada modulador. Além disso, por apresentar picos mais estreitos (wb 500ms), a frequência de aquisição utilizada é maior ( 100Hz), gerando arquivos que ultrapassam a capacidade de aplicativos comerciais. Assim, no desenvolvimento de sistemas próprios GcxGC, tem-se a necessidade de criar programas ou softwares para controle e tratamento de dados. Neste trabalho, foram desenvolvidos dois sistemas de controle distintos para sistemas GCxGC montados neste laboratório. O primeiro, denominado CROMATOGRAFIA, foi criado baseando-se no conceito de desenvolvimento de software da Fundação do Software Livre, ou seja, utilizou-se recursos de programação e de rede do sistema operacional Linux para realizar o controle e tratamento dos dados cromatográficos em um microcomputador e conversor A/D. Por outro lado, o segundo sistema, denominado LABVIEW, foi criado baseando-se no conceito de otimização de hardware, ou seja, utilizou-se um microcomputador e conversor A/D de médio desempenho em conjunto com uma linguagem de programação de alto nível específica para a automação de instrumentos. Ambos os sistemas de controle foram aplicados e validados em relação ao sinal monitorado, exatidão temporal e controle do modulador, verificando-se que o sistema LABVIEW apresentou resultados mais exatos para as análises qualitativa e quantitativa. Apesar de suas limitações iniciais, o sistema CROMATOGRAFIA com kernel soft real-time também foi aplicado com precisão e exatidão para controle dos sistemas GCxGC, salientando-se que seus módulos de tratamento e representação gráficas apresentaram melhor desempenho que aplicativos comerciais utilizados
Abstract: Comprehensive Two-dimensional Gas Chromatography (GCxGC) is an analytical technique used to separate hundreads of peaks and applied on different samples, like petrochemical products, enviromental and biological materials. This technique differs from convencional Gas Chromatography (GC) by use of two serial connected cappilary columns with different stationary phases and dimensions and a modulator, an interface that collects first column eluate fractions and reinjects them on second at regular time. Futhermore, data acquisition frequency must be higher ( 100Hz), because peak width acquired on GCxGC systems (wb 500ms), is narrow than conventional GC, resulting large data files to process with commercial softwares. On GCxGC system developments is necessary to create softwares for controlling and evaluating chromatographic data parameters. At this research two different control system were developed and applied to automate two home-made GCxGC systems. First control system, called CROMATOGRAFIA, was developed based on Free Software Foudation concept, i.e., it was developped on low level programming language and TCP/IP protocols within Linux O.S to control microcomputer and A/D conversor. On the other hand, second system, called LABVIEW, was developed on hardware optimize, i.e., it was developped with medium performance microcomputer and A/D conversor, using a commercial high-level visual programming language which is specific for automating instrument (NI Labview). Both control systems were checked performance by signal and real-time studies and applied for qualitative and quantitative analysis. LABVIEW system had better accuracy and precise results and, although its initial limits, CROMATOGRAFIA system with soft real-time kernel could be applied to accuracy and precise control GCxGC system with better 3D graphic representation and chromatographic data treatment than used commercial graphic softwares
Doutorado
Quimica Analitica
Doutor em Ciências
Mravcová, Ludmila. "Využití separačních technik na bázi plynové a kapalinové chromatografie s různým typem detektorů pro stanovení biologicky aktivních látek a vybraných xenobiotik." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2011. http://www.nusl.cz/ntk/nusl-233330.
Full textNohelová, Gabriela. "Bisfenol A ve vodním ekosystému." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2014. http://www.nusl.cz/ntk/nusl-217085.
Full textBarbosa, Paula Cristina Souza. "Padronização de óleos de Copaifera multijuga hayne por meio de técnicas cromatográficas." Universidade Federal do Amazonas, 2012. http://tede.ufam.edu.br/handle/tede/3340.
Full textCoordenação de Aperfeiçoamento de Pessoal de Nível Superior
As árvores do gênero Copaifera (Leguminosae), conhecidas popularmente como copaibeiras, exsudam um óleo-resina extensamente utilizado na medicina popular e por indústrias farmacêuticas e de cosméticos, devido às suas atividades cicatrizante e anti-inflamatória. Quimicamente, esses óleos se caracterizam pela presença de hidrocarbonetos sesquiterpênicos, sesquiterpenos oxigenados e ácidos diterpênicos. No entanto, a composição química desses óleos-resina é variável e ainda não se tem conhecimento dos fatores que as determinam, embora vários fatores bióticos e abióticos sejam considerados fontes dessa variação. Essa variação dificulta a padronização da composição química desses óleos, comprometendo seu controle de qualidade e consequentemente a qualidade dos produtos a que darão origem, fato que tem causado um grande entrave à sua maior aplicação e comercialização. Essa variabilidade em sua composição química já é bastante conhecida e relatada na literatura, mas a maioria dos estudos realizados têm se restringido a caracterizar quimicamente o óleo-resina e poucos tem se preocupado em estudar as causas dessas variações. O objetivo deste trabalho foi padronizar a composição química dos óleos de copaíba por meio de técnicas de cromatografia em fase gasosa acoplada à detectores de ionização de chama (CG-DIC) e espectrometria de massas (CG-EM) e cromatografia em fase gasosa bidimensional abrangente (CGXCG); analisar estatisticamente a influência de fatores abióticos como sazonalidade, tipo de solo e diâmetro à altura do peito (DAP), além da infestação por cupins, sobre a composição química desses óleos. Além disso, foram comparados 5 métodos de esterificação dos ácidos diterpênicos presentes nos óleos de copaíba envolvendo catálise ácida, que utilizam BF3/MeOH, H2SO4/MeOH e HCl/MeOH, levando-se em consideração suas eficiências e frequências analíticas, além do consumo e toxicidade dos reagentes utilizados, relação custo benefício e, principalmente, a possibilidade de alteração/degradação da estrutura dos constituintes quando aplicados em óleos de copaíba. Para isso foram obtidos óleos de copaíba de 3 coletas: em novembro de 2004 e novembro de 2005 (épocas consideradas secas) e em maio de 2005 (época considerada chuvosa). No total, 43 amostras de óleo-resina de copaíba foram coletadas na Reserva Ducke (Manaus-AM), de 33 espécimes diferentes, que possuíam diferentes DAP s e se encontravam em diferentes tipos de solo. As análises por CG-DIC e CG-EM permitiram a identificação de 35 constituintes: sendo 22 hidrocarbonetos sesquiterpênicos, 9 sesquiterpenos oxigenados e 4 ácidos diterpênicos. Enquanto a análise por CGxCG permitiu a identificação de outros 13 sesquiterpenos, além de 7 monoterpenos, inéditos em óleos-resina de copaíba. O β-cariofileno e seu óxido foram os constituintes majoritários em 29 e 11 amostras, respectivamente. As análises hierárquica por agrupamento (HCA) e de componentes principais (PCA) evidenciaram a existência de dois grupos distintos com diferentes perfis cromatográficos, em que foi comprovada apenas a influência do tipo de solo, sobre a composição química desses óleos. Outros fatores analisados como sazonalidade, DAP e infestação por cupins, não tiveram influência sobre a composição química dos óleos-resina de copaíba. Quanto aos métodos de esterificação, as análises das 5 metodologias testadas, apesar de terem sido reprodutíveis, não se mostraram eficientes, ao passo que não permitiram a identificação dos constituintes formados e levaram à formação de artefatos.
Tissandié, Loïc. "Analyse et valorisation des matières premières à odeur boisée : ciblage des composés odorants." Thesis, Université Côte d'Azur (ComUE), 2018. http://www.theses.fr/2018AZUR4244.
Full textThis Ph.D. dissertation sums up the work carried out as part of a thorough and systematic analytical study of woody-scented substances. These substances define a family of ingredients unanimously appreciated for their powerful notes, and sought by perfumers to compose some of the most emblematic accords in perfumery. The raw materials included in the frame of this study are the oils of Guaiac, Araucaria, Patchouli, Alaska Yellow Cypress, Vetiver, and Agarwood, as well as some of their by-products. Most of these raw materials are ingredients commonly used by the perfume industry. Their chemical specificity comes from their composition largely dominated by sesquiterpene derivatives, giving these extracts an undeniable molecular complexity. The main objectives of this Ph.D. thesis were to improve the knowledge of these raw materials in terms of chemical composition, to determine as much as possible the odorous compounds contributing to their odor, and finally to explore possible ways of valorization for these products on an industrial scale.The analytical methodology developed throughout this study required the combined use of a wide range of chromatographic, spectrometric, and spectroscopic techniques in order to characterize these raw materials as precisely as possible and achieve the isolation of their unknown constituents. Thus, our work revolved around four central tools: comprehensive two-dimensional gas chromatography-mass spectrometry (GC × GC-MS), gas chromatography-olfactometry (GC–O), preparative capillary-gas chromatography (pc-GC) and nuclear magnetic resonance (NMR). Almost 190 compounds have been isolated and characterized, 107 of which are described for the first time as constituents of natural extracts
Lacina, Petr. "Využití plynové chromatografie s hmotnostně spektrometrickou detekcí pro posouzení kontaminace odpadních a povrchových vod rezidui léčiv." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2012. http://www.nusl.cz/ntk/nusl-233363.
Full textPisani, Silvana Odete. "Contribuições para o desenvolvimento de método por GCxGC para a análise de nitro-HPAs em material particulado no ar." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-05082013-155917/.
Full textNitro-polycyclic aromatic hydrocarbons (nitro-PAHs) are potentially genotoxic, so there is a great interest in the analytical determination of these compounds in airborne particulate matter. The nitro-PAHs are emitted directly into the atmosphere by incomplete combustion or may be formed in situ from PAHs. In this work, results obtained from the development of an analytical method for nitro-PAHs by GCxGC are presented. The nitro-PAHs studied were: 1- nitronaphthalene, 2-nitronaphthalene, 1-nitropyrene, 2-nitropyrene, 2- nitrofluoranthene, 3-nitrofluoranthene, 1,3-dinitropyrene, 1,6-dinitropyrene, 2- nitrofluorene, 6-nitrochrysene, 7-nitrobenzo(a)anthracene, 9-nitroanthracene and 9- nitrophenanthrene. The separation of these compounds by GCxGC should simplify the pretreatment step of the airborne particulate organic extract. In GCxGC two capillary columns of different mechanisms of separation are coupled by an interface called modulator, which increase significantly the chromatographic resolution. The GCxGC system used in this work is equipped with a PTV injector, a dual-stage double jets CO2 cryogenic modulator and a flame ionization detector (FID). The separation was carried out using a nonpolar stationary phase 5% methyl phenyl polysiloxane in the first column (30 m / 0.25 mm / 0.25 µm) and a semipolar 14% cyanopropyl phenyl dimethyl polysiloxane in the second column. Different chromatographic conditions were tested: the PTV was programmed from 40-90ºC to 350ºC at 2.2 and 14.5ºC/s; the oven was programmed from 40-90ºC to 350ºC at 2.0, 2.5 and 3.0ºC/min; the modulation periods tested were 3, 4 and 5s. The injected volume was 2µL in splitless mode, the carrier gas (He) flow rate of 1 mL/min was constant and the FID detector was operated at 120 Hz. Validation parameters, such as the limit of detection (200 - 500 ng/mL) and quantitation (650 - 1600 ng/mL) were determined. For quantification, the internal and external standardization methods were tested, and through the results of this study, it can be shown that the determination of nitro-PAHs by GCxGC with the modulator used is possible if made by internal standardization method. The GCxGC system presented operational difficulties, particularly in the column connection and in the modulation zone. A partial connection of the columns resulted in mass loss of the analytes. The connection of the columns could be more effective if it was made by fusing the columns to a glass connector suitable for this purpose. Divided modulated peaks were frequently observed, which compromised the precision and accuracy of the results. The division of the peaks occurred randomly hindering the identification of the most likely cause for its occurrence. GCxGC chromatograms corresponding to unfractionated organic extracts of airborne particulate material from the sugarcane straw burning, from an area impacted by sugar cane burning emissions and from an urban area of São Paulo City showed the capability of the method.
Teng, Ming-Kai, and 鄧明凱. "Comprehensive two-dimensional gas chromatography (GCxGC) for atmospheric chlorofluorocarbons." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/90513370881690109656.
Full text國立中央大學
化學研究所
98
Abstract Comprehensive two-dimensional chromatography (GCxGC) opened a new era in improving separation resolution for very complex samples. It uses two columns of different polarity to provide orthogonal separation on a 2-D surface, which considerably increases the peak capacity and hence resolution compared to conventional 1-D chromatography. A typical commercial GCxGC system often uses a cryogenic modulator whose cost is high, and the consumption of cryogen creates additional financial burden. In contrast, many studies focused on developing valve-based types of modulators, which are simple in design and construction. Moreover, cryogen is not required. In our study we used a Deans’ switch to construct the modulator for GCxGC. When combined with a self-constructed thermal desorption unit, this system was able to analyze atmospheric chlorofluorocarbons (CFCs) at pptv level. The volatile sample peaks eluted from the first column (DB-1 60 m) were sliced into sample pulses by the Deans’ switch and sent to the second column (PLOT 0.2 m) for the second dimensional separation. For optimal GCxGC separation of CFCs the modulation pulse and period were set at 0.2 s and 3 s, respectively.By varying the sample size of a pressurized air sample, the linearity of the method was better than 0.990. The precision at atmospheric concentrations was better than 4.74% (RSD). The Deans’ switch-GCxGC method was further tested by continuous measuring outdoor ambient air, and compared the atmospheric variability of CCl2F2 (CFC-12) and CClF2CCl2F (CFC-113) with that from the corresponding 1D GC results. The variability of CFC-12 and CFC-113 denoted by RSD was 3.85% and 3.49%, respectively, for GCxGC versus 2.63% and 3.34%, respectively, for 1D GC. The comparable results suggest that our Deans’ switch-GCxGC method is sufficiently robust to analyze atmospheric CFCs.
(8082794), Joseph C. Cacciatore. "Electronics Authenticity Testing Using Comprehensive Two-Dimensional Gas Chromatography." Thesis, 2019.
Find full textTechnology has become increasingly more prevalent in all aspects of society since the age of the computer. The United States Military has successfully integrated the powerful processing capabilities of computers to increase the proficiency and lethality of its Soldiers, Sailors, Marines, and Airmen. However, this increased lethality comes at risk due to the inherent vulnerabilities of computer systems to spyware, malware, and counterfeit components. Inspired by the ability of canines to seek out and find electronic devices, this research sought methods to characterize components by their “scent” using precise analytical tools. Using these tools, this thesis sought to develop and utilize non-invasive methods to show proof-of-concept for electronic device classification by volatile compounds unique to different types of components. The findings of this research proved that electronic components that vary by age, origin, type, or manufacturer emit different volatile compounds available for detection using modern two-dimensional gas chromatography and solid-phase microextraction technologies. If developed further, the methods used in this research have the potential for application in the United States Department of Defense to ensure that all electronic components installed in their systems are authentic, come from a trusted source, and can be relied upon in even the most stressful operating conditions.
Harvey, PM. "Pneumatic-modulation comprehensive two-dimensional gas chromatography for environmental analysis." Thesis, 2013. https://eprints.utas.edu.au/16780/1/Harvey_whole_thesis_ex_pub_mat.pdf.
Full textChung, Yung-shin, and 鍾永信. "The Modulator Systems for Two Dimensional Micro-Chip Gas Chromatography." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/61858595807851889082.
Full text國立臺灣師範大學
化學系
98
The goal of this research is to investigate three different configurations of two dimensional gas chromatography (2D-GC) when using two of micro electromechanical system (MEMS) technology fabricated -column chips coated with DB-1 and DB-210 as stationary phases. Taking advantage of dissimilar retentions for VOCs of the two stationary phases and 2D-GC, we resolve the problem of insufficient separation using single, short -column chip. Commercial modulators for 2D-GC are cryogenic or valve-based. However, cryogenic modulators need to have cylinders of liquid nitrogen or carbon dioxide. It violates the unique purpose of portability for μGC. Hence, μGC should use only cryogenic free modulators. The three modulator systems for 2D-GC investigated in current study are Heart cutting GC × GC system, Deans switch GC - GC system, and Stop-flow GC - GC system. The Heart cutting GC × GC system and Stop-flow GC - GC system can separate eleven VOCs of similar boiling points within five minutes. Although the Heart cutting GC × GC system causes the loss of sample mass due to splitting, it achieves better separations. The Deans switch GC - GC system links to two detectors so that it increases the efficiency of experiment. Comparing with the same VOCs, this system only takes a half of time to finish the separation of these. Stop-flow GC - GC system is the lightest in hardware requirements, but it is also the most time consuming among three modulator systems.
Tian, Tze-Feng, and 田士鋒. "Alignment Algorithm for Comprehensive Two-dimensional Gas Chromatography-Mass Spectrometry." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/71561326334152718718.
Full text國立臺灣大學
電機工程學研究所
99
Three works are included in this thesis including 1) an algorithm for Comprehensive two-dimensional gas chromatography mass spectrometry alignment, 2) 3Omics: a web based systems biology visualization tool for integrating human transcriptomic, proteomic and metabolomic data, and 3) HMO: a tool for understanding the human metabolome. A novel peak alignment algorithm, 2DGCMS-aligner, has been developed for two-dimensional gas chromatography time-of-flight mass spectrometry (GCxGC/TOF-MS) data. 2DGCMS-aligner uses the netCDF data generated from the instrument as input directly. It detects blobs, clusters of pixels that are brighter or darker than their surround in a chromatogram, of each GCxGC/TOF-MS raw data to generate blob tables instead of peak tables to perform alignment. 2DGCMS-aligner correlates the blobs with Euclidean distance of the first- and second retention times in the blob tables and the mass spectra with Pearson’s correlation coefficient. This alignment algorithm in 2DGCMS-aligner can be applied to GCxGC-MS data generated by either consistent or inconsistent instrument environment to adjust retention time shifts along both chromatographic dimensions caused by uncontrollable fluctuations in temperature and pressure, matrix effects and stationary phase degradation. 2DGCMS-aligner also includes an option to correct baseline on raw data directly. The performance of 2DGCMS-aligner peak alignment algorithm was compared and demonstrated with three existing alignment methods on the two sets of GCxGC-MS data sets acquired in different experiment conditions and a mixture of standard metabolites. 3Omics: a web based systems biology visualization tool for integrating human transcriptomic, proteomic and metabolomic data was developed to visualize and rapidly integrate multiple inter- or intra-transcriptomic, proteomic, and metabolomic human data. A biochemical cascade is generated through consolidation of transcript, protein, and metabolite data and implements via the application of five commonly used analyses of correlation network, co-expression, phenotyping, KEGG pathway enrichment, and GO enrichment. 3Omics incorporates the advantages and operations of existing software into a single platform, therefore simplifying the data analysis procedure and enabling the user to perform a one-click integrated analysis for free. Visualization and analysis results are downloadable for further user customization and analysis. The 3Omics software can be freely accessed at http://cmdd.csie.ntu.edu.tw/~3omics. Last part of this thesis work is the construction of Human Metabolome Ontology (HMO). Final step in current metabolomics studies involves assessment and biological interpretation of metabolome. It often requires tedious manual collections of literature or linking information scattered in Gene Ontology, BRENDA, KEGG Brite, KEGG Pathway, Human Metabolome Database, OMIM and so on. We developed the HMO to facilitate integration of biological functions, and chemical classification of metabolome and comprehensive understanding of metabolome and its target interactions as the common language and knowledge framework allowing further computational analysis. HMO consists of three independent ontologies: biological functions, chemical taxonomies and metabolome targets. It provides a comprehensive metabolome centered resource that enables the sharing and reuse of the know-ledge across domains of ontologies.
Liu, Wen-tzu, and 劉文治. "Monitoring CFC and HCFC using Oxygen-doping two dimensional gas chromatography." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/hp6qmj.
Full text國立中央大學
化學研究所
96
The continual anthropogenic chlorofluorocarbons (CFCs) are known to destroy stratospheric ozone because of their long lifetimes and chemical stability. The advent of the Montreal Protocol caused total phase-out of CFCs in 1996. The consumption of the replacements, hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs), have been increasing rapidly. Although they have limitted or no ozone depleting potentials (ODPs), they are very potent green house gases. In this study, a gas chromatographic (GC) method was developed to simultaneously measure CFCs, HCFCs and HFCs in the atmosphere. The system involved an automated preconcentration unit using chemical adsorbents combined with two dimensional GC equipped with electronic captured detector (ECD) for measuring CFCs. For HCFCs and HFCs the oxygen-doping ECD method was employed to enhance the sensitivity. The system was tested on campus and at the Taishi EPA monitoring station. Limited emissions of CF2ClCFCl2 and CCl4 were found, which can serve as a useful quality assurance tool to validate measurements. Other more variable species, i.g., CF2Cl2, CF2ClBr and CHCl3, were detected revealing the existence of sources. For the doping system deployed in Taishi station, strong emissions of CH2Cl2 with concentration excess of 8 ppb relative to the baseline condition was found. The datasets were further examined by Gaussian distribution, which is a novel approach to reveal variability and sources of halocarbons.
Wang, Pei-Hsia, and 王珮霞. "Comprehensive two-dimensional gas chromatography analysis VOCs composition in vehicle emission." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/41509311749905171850.
Full text國立中央大學
化學學系
104
Comprehensive two-dimensional gas chromatography (GC×GC) is the preferred choice of analysis for complex volatile organic compounds (VOCs). When coupled with time-of-flight mass (ToF) spectrometry, termed GC×GC-ToF, it becomes a powerful technique to analyze fuels, perfumes, aromas, environmental samples, etc. with complex chemical compositions. Compared to conventional one-dimensional GC, GC×GC greatly enhances peak capacity via the use of two columns of different phases and lengths for orthogonal separation. Modulation plays a central role in GC×GC performance. The high cost in ownership and operation of a commercial GC×GC system equipped with a cryogenic modulation motivated the development of cryogen-free modulation. In this study, a valve-based modulator based on the Deans switch served as an alternative to the commercial counterpart without the use of cryogen. The switching of an auxiliary gas stream of a Deans switch that cuts peaks from the column of first dimension (1D) into fine slices to the short column of secondary dimension (2D) created the effect of modulation. Because of the low concentrations of VOCs in ambient air, usually at only sub-ppbv levels, an air sample would require substantial preconcentration before GC analysis. As a result, a self-built preconcentrator was connected to a GC×GC system, which was equipped with two columns of DB-1 (60 m×0.32 mm i.d.×1 μm d.f.) as the 1D column and Rtx-502.2 (2 m×0.32 mm i.d.×1.8 μm d.f.) as the 2D column to display the orthogonality of non-polarity vs. mid-polarity. Flame ionization detection (FID) was adopted by exploiting its high acquisition rates and reliability. Instead of using the commercial GC×GC software packages, a general-purpose software, Surfer®8, was used to plot GC×GC the results. The analytical precision of 7% as the RSD was achieved by repeated analysis of the PAMS standard gas mixture at sub-ppbv level. Ambient samples collected in a long highway tunnel by canisters and sorption tubes were analyzed for system validation. Furthermore, as the trial studies, PM2.5 aerosol samples collected on filter papers were attempted by thermal desorption of the filter paper. Compound identification was made with GC-MS by analyzing parallel samples to reveal the chemical identities of the major constituents of both the air and PM samples. While all the VOCs found in the canisters were non-polar hydrocarbons due to the lack of photochemistry in the tunnel, selected oxygenated VOCs (o-VOCs) were found in the aerosol sample owing to the extended oxidation process in the atmosphere.
Lin, Wei-chun, and 林維雋. "Analysis and Study of Alkylphenols in Biosamples by Gas Chromatography/Mass Spectrometry and Two-Dimensional Gas Chromatography/Mass Spectrometry." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/56287172862231456849.
Full text國立中央大學
化學研究所
95
Alkylphenol polyeyhoxylates (APEOs), one of the most important classes of nonionic surfactants, were introduced in the 1940s. Because of their great soaking, cleaning and emulsifying abilities, they are widely used in the household detergents, textile industries, dyeing industries and other commercial applications in Taiwan. APEOs in aquatic environment are biodegraded into alkylphenols (APs) and relative metabolites. Indeed, APs have been estimated that they are persistence organic pollutions which are not easily biodegraded by microorganisms and demonstrated as endocrine disruptors which can cause estrogenic effects in organisms. This effect has raised increasing concern about their impact on wildlife and human health. Consequently, it is necessary to develop analytical methods for routinely determining the levels of alkylphenolic compounds in the Taiwanese environment and observe the biodegradation of 4-nonylphenol isomers. The first part of this study is using steam distillation extraction and derivatization methods coupled with gas chromatography/mass spectrometry (GC/MS) to determine the levels of alkylphenol compounds in fish. The silylating agent used was BSTFA+1% TMCS and the optimal reaction time and temperature were 30 min and 80°C. Under these conditions, the recovery of OP and NP was above 66.8% and 67.4%, respectively. RSD ranged from 2.1 to 10.4%. The concentration of 4-t-OP and 4-NPs ranged from 13-202.9 ng/g and from 9.2-529.7 ng/g, respectively. The second part of this study is deterimining the alkylphenols in commercial milk and breast milk. The method involves extracting a sample by liquid-liquid extraction and solid-phase extraction and then clean up by anhydrous sodium sulfate and aluminum oxide. Alkylphenols were identified and quantitated by gas chromatography /mass spectrometry (GC/MS) in selected ion monitoring (SIM) mode. Various solution compositions were evaluated as rising solution. The limit of quantitation (LOQ) were less than 0.2 ng/g for 4-t-OP and 1.5 ng/g for 4-NP in 20 g breast milk. In 20 breast milk samples, 4-t-OP was detected in 8 samples and concentration ranged from 0.4 to 1.14 ng/g, while 4-NPs was detected in 19 samples and concentration ranged from 1.74 to 11.58 ng/g. In 7 commercial milk samples, 4-t-OP was detected in 1 samples and concentration was 0.14 ng/g, while 4-NPs was detected in all testing samples and concentration ranged from 2.93 to 8.84 ng/g. The results of the recovery and reproducibility for the SPE method indicated that it’s better to use methanol:water=1:1 (v/v) solution than ethanol:water=1:1 (v/v) as rinsing solution. The spiked recovery of 4-t-OP and 4-NPs were above 77.5% while RSD was below 9% which indicated this method is reliable and sensitive for determining traces of alkylphenols residues in milk. Finally, because of different biodegradation rates, estrogenic effect and bioaccumulation potentials of each 4-nonylphenol isomer, only a few 4-nonylphenol isomers have higher estrogenic effects. So we used 100 m GC column and two-dimensional gas chromatography (GC x GC) combined with quadrupole mass spectrometer to separate 4-nonylphenol isomers more further in fish and breast milk samples. The results indicated that the more branched isomers of 4-nonylphenol isomers which may be more resistant to biodegradation than the less branched isomers in organisms. Furthermore, we analyzed five technical 4-nonylphenol standards from different vendors by GC x GC-MS system. Different patterns were observed from these standards. Hence, the GC x GC-MS system can be used as a rapid screening tool to access nonylphenol pollution associated with chemical migration and source apportionment studies.