Dissertations / Theses: 'GC'

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Ferreira, Ernesto Correa. "Softwares para cromatografia gasosa bidimensional abrangente (GC x GC)." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250202.

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Orientador: Fabio Augusto
Tese (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

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Шемедюк, Н. П. "Регуляція клітинного циклу GC-1 spg і GC-2 spd." Thesis, Київський національний університет технологій та дизайну, 2020. https://er.knutd.edu.ua/handle/123456789/15585.

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Nakovich, Laura. "Analysis of Biogenic Amines by GC/FID and GC/MS." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/35027.

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Low levels of biogenic amines occur naturally, but high levels (FDA sets 50 ppm of histamine in fish as the maximum allowable level) can lead to scombroid poisoning. Amines in general are difficult to analyze by Gas Chromatography (GC) due to their lack of volatility and their interaction with the GC column, often leading to significant tailing and poor reproducibility. Biogenic amines need to be derivatized before both GC and HPLC analyses. The objective of this research was to develop a relatively fast, reproducible method to derivatize and quantitate biogenic amines in fish at trace levels using GC/FID. The derivatizing reagent used in the experiments was propyl chloroformate, useful for aqueous samples. To confirm the identity of six derivatized biogenic amines GC/MS was used. To our knowledge no reference spectra for these derivatives has been published. It was concluded that best results are obtained using a Cold-On-Column (C.O.C.) inlet with a short column (15 meters), thick film stationary phase (ZB-5, 1.00Î¼m df), and with recommendations to cut 40 cm from the inlet end of the column every 25 injections when using C.O.C. Duplicate samples of Atlantic Salmon were analyzed on days 0, 3, and 5. Levels of histamine were below 50 ppm for days 0 and 3, but day 5 showed average levels of 160 pm (cadaverine), 1000 ppm (histamine), and 350 ppm (tyramine). Good precision of six amine stardards at 50 ppm was shown: heptylamine 5.2%, putrescine 5.6%, cadaverine 5.0%, histamine 9.9%, tyramine 5.1%, and spermidine 6.2% RSD.
Master of Science

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Zhang, Penghan. "Application of GC×GC-MS in VOC analysis of fermented beverages." Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/323992.

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GC×GC is an efficient tool for the analysis of volatile compound. However, improvements are still required on VOC extraction, GC×GC setup and data processing. Different sample preparation techniques and GC×GC setup were compared based on the literature study and experimental results. Each VOC extraction technology has its own drawbacks and needs new developments. There wasn’t an ideal sample preparation technique to recover all the VOCs from the beverage sample. Furthermore, the VOCs recovered by different techniques were very different. The discussion of the pros and cons of the different techniques in our study can serve as a guide for the further development and improvement of these techniques. Combining the results from different sample preparation techniques is necessary to achieve a higher coverage of global VOC profiling. For the known fermentative aromatic compounds, the best coverage can be reached by using SPME together with SPE for beer, and VALLME for wine and cider. A fine GC×GC method development involves modulator selection, column combination and parameter optimization. Thermal modulator provides high detection sensitivity and allow exceptional trace analysis. Since the analytes coverage is the most important factor of in beverage VOC profiling, thermal modulation is a better choice. In fermented beverages, there are more polar compounds than non-polar compounds. The most suitable column combination is polar-semipolar. Same column diameters shall be used to minimize the column overloading. GC×GC parameters must be optimized. These parameters interact with each other therefore statistical prediction model is required. Response surface model is capable of doing this job while using a small number of experimental tests. The nearest neighbor distance was a suitable measurement for peak dispersion. Column and detector saturations are unavoidable if the metabolic sample is measured at one dilution level, incorrect peak deconvolution and mass spectrum construction may happen. Data processing results can be improved by a two-stage data processing strategy that will incorporate a targeted data processing and cleaning approach upstream of the “standard” untargeted analysis. Our experiments show a significant improvement in annotation and quantification results for targeted compounds causing instrumental saturation. After subtracting the saturate signal of targeted compounds, the MS construction was improved for co-eluted compounds. Incomplete signal subtraction may occur. It leads to the detection of false positive peaks or to interferences with the construction of mass spectra of co-diluted peaks. High-resolution MS libraries and more accurate peak area detection methods should be tested for further improvement.

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ZHANG, PENGHAN. "Application of GC×GC-MS in VOC analysis of fermented beverages." Doctoral thesis, country:IT, 2021. http://hdl.handle.net/10449/72495.

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GC×GC is an efficient tool for the analysis of volatile compound. However, improvements are still required on VOC extraction, GC×GC setup and data processing. Different sample preparation techniques and GC×GC setup were compared based on the literature study and experimental results. Each VOC extraction technology has its own drawbacks and needs new developments. There wasn’t an ideal sample preparation technique to recover all the VOCs from the beverage sample. Furthermore, the VOCs recovered by different techniques were very different. The discussion of the pros and cons of the different techniques in our study can serve as a guide for the further development and improvement of these techniques. Combining the results from different sample preparation techniques is necessary to achieve a higher coverage of global VOC profiling. For the known fermentative aromatic compounds, the best coverage can be reached by using SPME together with SPE for beer, and VALLME for wine and cider. A fine GC×GC method development involves modulator selection, column combination and parameter optimization. Thermal modulator provides high detection sensitivity and allow exceptional trace analysis. Since the analytes coverage is the most important factor of in beverage VOC profiling, thermal modulation is a better choice. In fermented beverages, there are more polar compounds than non-polar compounds. The most suitable column combination is polar-semipolar. Same column diameters shall be used to minimize the column overloading. GC×GC parameters must be optimized. These parameters interact with each other therefore statistical prediction model is required. Response surface model is capable of doing this job while using a small number of experimental tests. The nearest neighbor distance was a suitable measurement for peak dispersion. Column and detector saturations are unavoidable if the metabolic sample is measured at one dilution level, incorrect peak deconvolution and mass spectrum construction may happen. Data processing results can be improved by a two-stage data processing strategy that will incorporate a targeted data processing and cleaning approach upstream of the “standard” untargeted analysis. Our experiments show a significant improvement in annotation and quantification results for targeted compounds causing instrumental saturation. After subtracting the saturate signal of targeted compounds, the MS construction was improved for co-eluted compounds. Incomplete signal subtraction may occur. It leads to the detection of false positive peaks or to interferences with the construction of mass spectra of co-diluted peaks. Highresolution MS libraries and more accurate peak area detection methods should be tested for further improvement.

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Silva, Rosselei Caiél da. "Comparação entre métodos cromatográficos, empregando GC-ECD, GC-FPD E GC-MS, e espectrofotométrico para determinação de ditiocarbamatos em alface." Universidade Federal de Santa Maria, 2005. http://repositorio.ufsm.br/handle/1/10469.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico
Brazil is the third largest market for pesticide sales in the world, with almost 400 active ingredients registered in the country, including five dithiocarbamates. This pesticide class consists of very important protective nonsystemic fungicides with broad-spectrum activity registered for the control of fungal deseases on a large variety of crops. Due to its low acute toxicity, combined with strong action, low-cost production and low environmental persistence, the total amount used of these compounds used is still increasing world-wide. Many methods to determine dithiocarbamates are based on acid hydrolysis in the presence of stannous chloride and analysis of the evolved CS2 by different techniques. In the present work, three chromatographic methods were validated for the quantification of dithiocarbamates residues in lettuce using Gas Chromatography with Electron Capture Detection (GC-ECD), Flame Photometric Detection (GC-FPD) and Mass Spectrometry (GC-MS), and these three methods were compared with a spectrophotometric method.The experimental conditions for the chromatographic analysis were: capillary column CP-Sil 8 CB (50 m x 0.32 mm i.d. x 1.2 μm film thickness); temperature program column oven: 45 oC (1 min) - 10 oC min-1 to 250 oC (0 min); flow-rate of the carrier gas (Helium) 2 mL min-1; volume of injection 4 μL, with split 1:10 for GC-ECD and GC-MS and 1:15 for GC-FPD; temperature of the detector was 300 oC for ECD and 250 °C for FPD. The transferline and trap were heated to 230 °C and the manifold to 120 °C. The spectrophotometric analysis was done in 435 nm, after complexation of the CS2 with diethanolamine and copper. In the validation study of the methods, the following parameters were assessed: detection limit (LOD), quantification limit (LOQ), precision (under repeatability and reproducibility conditions) and recovery. Method LODs in the sample were 0.01 mg CS2 kg-1 and 0.28 mg CS2 kg-1 and LOQs were 0.02 mg CS2 kg-1 and 0.4 mg CS2 kg-1 for chromatographic and spectrophotometric methods respectively. The calibration curves were linear with correlation coefficients r2> 0.99. Acceptable precision with RDS% between 2.8 and 15.9 was obtained. The recoveries ranged from 87.7 to 107.4%. The results obtained in the validation step allow us to conclude that the methods are quite appropriate to determine residues of dithiocarbamates in lettuce. However, the chromatographic methods have shown a lot of advantages such as to be more sensitive, simple and faster than the spectrophotometric method. Beside, the sample preparation can be done simultaneously for a great number of samples and in a simplified way.
O Brasil é o terceiro maior mercado mundial de pesticidas, com aproximadamente 400 ingredientes ativos registrados no país, incluindo cinco ditiocarbamatos. Esta classe de pesticidas é composta por importantes fungicidas de ação não sistêmica e de amplo espectro de atividade empregados para controle de fungos em uma grande variedade de culturas. Devido a baixa toxicidade, combinado com forte atividade, baixo custo de produção e baixa persistência ambiental, a quantidade destes compostos tem aumentado no mundo inteiro. Muitos métodos para determinar ditiocarbamatos estão baseados na hidrólise ácida, em presença de cloreto de estanho II, e análise do CS2 gerado por diferentes técnicas. Neste trabalho, foram validados três métodos cromatográficos para a quantificação dos resíduos de ditiocarbamatos em alface empregando Cromatografia Gasosa com Detecção por Captura de Elétrons (GC-ECD), Detecção Fotométrica de Chama (GC-FPD) e Detecção Espectrométrica de Massas (GC-MS), e comparou-se com o método espectofotométrico. As condições para as análises cromatográficas foram: coluna capilar CP-Sil 8 CB (50 m x 0,32 d.i x 1,2 μm de espessura do filme); programa de temperatura do forno da coluna: 45 °C (1 min) com incremento de 10 °C min-1 à 250 ° C (0 min); vazão do gás de arraste em 2 mL min-1; volume de injeção de 4 μL com split 1:10 para GC-ECD e GC-MS, e 1:15 para GC-FPD; temperatura do ECD foi 300 °C e do FPD de 250 °C. O transferline e o trap foram aquecidos a 230 °C, e o manifold a 120 °C. A análise espectrofotométrica foi realizada a 435 nm, após a complexação do CS2 com dietanolamina e cobre. Para a validação dos métodos seguiram-se os seguintes parâmetros: limite de detecção (LOD), limite de quantificação (LOQ), linearidade, precisão (repetitividade e precisão intermediária) e recuperação. Os LODs na amostra foram 0,01 e 0,28 mg CS2 kg-1, e os LOQs foram 0,02 e 0,4 mg CS2 kg-1 para os métodos cromatográficos e espectrofotométrico, respectivamente. As curvas analíticas apresentaram r2> 0,99. Os estudos de precisão apresentaram resultados aceitáveis, com valores de RSD% entre 2,8 e 15,9. As recuperações foram de 87,7 a 107,4%. Através dos resultados obtidos na validação, pode-se concluir que os métodos são apropriados para determinar resíduos de ditiocarbamatos em alface. Entretanto, os métodos cromatográficos têm apresentado várias vantagens como elevada sensibilidade, simplicidade, além de serem mais rápidos que o método spectrofotométrico, pois é possível realizar o preparo de um grande número de amostras simultaneamente.

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MacGillivray, Tanya Frances. "Analysis of lichens under environmental stress using pyrolysis-GC-MS and pyrolysis-GC-FID." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0018/MQ54933.pdf.

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Pedroso, 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.

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Orientador: Fabio Augusto
Tese (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

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Lundgren, Erik. "Utredning om GC-bro över Bodån." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-61381.

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Målet med detta examensarbete har varit att undersöka och ge förslag på lämpliga lösningar för att gångtrafikanter ska slippa korsa riksväg 97. I ett inskickat medborgarförslag föreslås en konstruktion av en GC-bro över Bodån i syfte att uppnå en säkrare miljö för gångtrafikanter. I detta examensarbete har jag undersökt olika alternativ och tre förslag har presenterats. Dessa har kostnadsuppskattats med hjälp av ett antal företag. Även en grov översiktsplan har tagits fram för de olika alternativen. Alternativen jämfördes utifrån kostnad, trafiksäkerhet, estetik, rekreation och hur väl alternativen tillgodoser medbrogarförslaget. Utifrån de uppsatta kriterierna blev slutsatsen att den mest lämpliga lösningen är att konstruera en limträbro över Bodån samt en stålbro under järnvägsbron. Denna lösning uppfyller behovet av en mer trafiksäker övergång enligt medborgarförslaget och bedöms även som det mest tilltalande ur ett estetiskt perpektiv.

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Reed, Gail L. "Fast GC: Applications and Theoretical Studies." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/29085.

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Experimental data are presented for the first time in support of a theoretical model of band broadening proposed by Blumberg (1997). This model addresses the effects of the compressibility of the mobile phase in gas chromatography and presents an equation derived from only two mutually independent variables. Solutions of decane and tridecane in hexane were analyzed at pressures ranging from 15 to 150 psi. Six different columns were used that varied in length, internal diameter and film thickness. Theoretical plate heights were obtained from this data and plotted versus the average linear carrier gas velocity (Golay type plots). These plots showed that at high pressures the Blumberg model fit the experimental data statistically significantly better than the earlier model proposed by Golay. The Blumberg model also accurately predicts the relationship between the optimum linear carrier gas velocity and the temperature. The second part of this work explores the scope and limitations of fast temperature programming in the fast GC analyses of various sample types. These samples included polycyclic aromatic hydrocarbons (PAHs), hydrocarbons and food samples. Programming rates of up to 1200Â° C/min were used. These fast programming rates were obtained by using "flash"â ¢ temperature programming, controlled by resistive heating of a metal tube that enclosed a capillary column. The precision of peak data was found to be good, less than 5% for peak areas and 4% for retention times. However, a slight, but statistically significant decrease in peak areas was seen above programming rates of 240Â° C/min. Microwave assisted extraction (MAE) was used to extract 2,6-di-(tert-butyl)-4-methylphenol, BHT, from chewing gum and breakfast cereal. The extraction was followed by a fast GC analysis (less than 4 minutes) using "flash"â ¢ temperature programming. MAE reduced the sample preparation time, from hours to minutes, and consequently reduced, the total analysis time. Extraction times longer than 5 minutes gave decreased recoveries of BHT.
Ph. D.

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Sýkora, Richard. "Využití GC/MS při analýze léčiv." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2011. http://www.nusl.cz/ntk/nusl-216709.

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This diploma thesis is based on the current issue of the presence of pharmaceuticals in various components of the environment. Concerning the contamination by residues of pharmaceuticals the most affected environment is the aquatic environment where these substances leaks especially from wastewater treatment plants, which eliminate them during the cleaning process only partially. This work is focused on the selected group of pharmaceuticals, non-steroidal anti-inflammatory drugs (salicylic acid, ibuprofen, caffeine, naproxen, ketoprofen, diclofenac) in waste water. For analysis purposes two types of sampling were used and compared: the conventional spot sampling of wastewater and the sampling using passive samplers POCIS. The sampling took place at the inflow and outflow of the wastewater treatment plant in Brno Modřice. The solid phase extraction (SPE) using Oasis HLB columns was used as the extraction method. Extracted sample was derivatized then. Derivatization agents were: MSTFA (N-methyl-N-(trimethylsilyl)trifluoroacetamid) and BSTFA (N, O-bis(trimethylsilyl) trifluoroacetamid). The final analysis was performed using gas chromatography with mass spectrometric detection Time-of-Flight (GC/TOF-MS).

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Souza, Rita de Cassia Zacardi de. "Avaliação das frações voláteis de espécies de Aniba por microextração em fase sólida acoplada a cromatografia gasosa (SPME-GC) e cromatografia gasosa bidimensional abrangente (GC x GC)." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/248376.

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Orientadores: Lauro Euclides Soares Barata, Fabio Augusto
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: O presente trabalho é apresentado em dois capítulos: o primeiro compreende o desenvolvimento de uma metodologia de diferenciação entre duas espécies de Aniba frequentemente confundidas, Aniba parviflora e Aniba rosaeodora e o segundo compreende o estudo da composição química dos óleos essenciais de Aniba parviflora através de cromatografia gasosa acoplada a espectrometria de massas (CG-EM), cromatografia gasosa com detector de ionização de chama (CG-DIC) e cromatografia gasosa bidimensional abrangente acoplada à espectrometria de massas (CG × CGEM). Para a diferenciação das espécies foi utilizada a avaliação das suas frações voláteis (headspace) através da SPME-CG (Microextração em Fase Sólida acoplada a Cromatografia Gasosa). Foram analisadas um total de 100 amostras de folhas das duas espécies e a diferenciação foi feita através do tratamento quimiométrico dos dados obtidos. Foram analisados ainda óleos essenciais das folhas e da madeira de A. parviflora obtidos por arraste a vapor. O estudo destes forneceu além da composição química, a análise quantitativa dos seus componentes. Por fim foi realizada a comparação da técnica de CG-EM com a inovadora técnica de CGxCG-EM que possibilitou um aumento de 50% na identificação dos componentes e aproximadamente de 80% na separação e detecção. Os resultados obtidos permitem dizer que e possível diferenciar duas espécies botanicamente vizinhas através de técnicas analíticas de maneira objetiva com respaldo estatístico
Abstract: This work consists of two main parts: The first part involves the development of a differentiation methodology between two Aniba species that are often confused with one another, they are Aniba parviflora and Aniba rosaeodora. The second part involves the chemical composition study of Aniba parviflora essential oils through gas chromatography coupled to mass spectrometry (GC-MS), gas chromatography with flame ionization detection (GC-FID) and comprehensive two-dimensional gas chromatography (GC × GC- MS). In the first part, the species differentiation was performed using SPME-GC and chemometric tools for the assessment of their volatile fraction (headspace). A total of 100 different leaf samples coming from distinct individuals of these two species were examined and the differentiation was made based on the SPME-GC chromatograms data that were treated using chemometric tools. In the second part the essential oils of A. parviflora coming both from leaves and wood were also analyzed and its study resulted in the oils chemical composition and in the quantitative analyses of its components. This work provided also a comparison between two techniques, GC-MS and the innovative GCxGC-MS. The later technique allowed an increase of at least 80 % of total components separation and detection and an increase of more than 50 % of the total identified components
Mestrado
Quimica Organica
Mestre em Química

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Belhassen, Émilie. "Ciblage des composés d'impact olfactif dans les substances naturelles à odeur boisée : étude de l’huile essentielle de vétiver." Thesis, Nice, 2014. http://www.theses.fr/2014NICE4067.

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Depuis plusieurs siècles les racines de vétiver sont utilisées en Inde du sud afin de prévenir l'érosion du sol. Par la suite, la production de l’huile essentielle des racines de vétiver a permis d’alimenter l’industrie de la parfumerie. De nos jours, cette matière première sert principalement à la confection de parfums masculins, où elle apporte des notes boisées, terreuses, de pamplemousse et de rose. En dépit de son utilisation abondante, la nature des molécules responsables de son odeur est encore un sujet de controverses. Dans un premier temps, l’étude des constituants volatils a été entreprise, et certaines incohérences de la littérature ont été mises en évidence. Par la suite, l'analyse par GC × GC d'huiles de vétiver d'origines différentes a permis de mieux comprendre la variabilité de cette matière première. Elle a également facilité l’identification de substances odorantes d'impact, réalisée par GC-O sur l’huile essentielle et l’acétate de vétiveryle. La synthèse de plusieurs dérivés zizaane a également été développée pour confirmer certains des résultats de la caractérisation des odorants. Nous avons également développé une nouvelle procédure pour la synthèse à grande échelle de dérivés nor-zizaane à puissante odeur de vétiver. Lors de cette étude, nous avons développé une nouvelle réaction de décarbonylation utilisant le peroxyde d'hydrogène en milieu alcalin. Cette réaction a pu être appliquée sur différents aldéhydes aliphatiques, les meilleurs résultats étant obtenus avec des substrats α-disubstitués. Une bonne sélectivité a également pu être observée sur les aldehydes linéaires, qui conduisent généralement à l’acide dans de telles conditions
Vetiver have been used from centuries in South India to prevent soil erosion and later on, the essential oil produced by distillation of this raw material has begun to been largely employed in perfume composition. This essential oil is now abundantly used in the confection of men perfumes for its pleasant fragrance of wood, earth, grapefruit and rose. However, paradoxically, the nature of its impact odorants still remains controversial. At first, we have realized the review of the volatile constituents identified in this material, and some discrepancies of the literature have been highlighted. Then, the analysis by GC × GC of vetiver oils from different origins has permitted to better understand the composition of these materials. Subsequently, the characterization of the impact odorants of Haitian vetiver essential oil and vetiveryl acetate has been performed by GC-O. To confirm some of the results of this investigation, several zizaane derivatives have been synthesized, and in the course of this study, we developed a new reaction of decarbonylation of aliphatic aldehydes using alkaline hydrogen peroxide. A new procedure for the large scale preparation of highly potent nor-zizaane odorants could then be developed. Moreover, when exploring the scope and limitations of this reaction, it appeared to be applicable on various aliphatic aldehydes. The best results were obtained with α-disubstituted substrates, and a surprisingly good selectivity of this reaction was noticed on linear aldehydes

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De, Vos Betty-Jayne. "Gas chromatography coupled with ion trap mass spectrometry (GC-MS and GC-MS-MS) - for arson debris analysis." Diss., Pretoria : [s.n.], 2005. http://upetd.up.ac.za/thesis/available/etd-02082006-160506.

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Dursun, Hayrettin. "Determination Of The Postexplosion Residues Of Nitro Group Containing Explosives In Soil With Gc-ms And Gc-tea." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12609014/index.pdf.

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There is an increase in bombing assaults in recent years in our country. Determining the explosive material used in these cases by the quick and correct analysis of the evidence obtained after the explosions, is an important starting point for the investigations which are done to reach the perpetrators. The forensic chemistry investigations have to be correct, exact and rapid in order to reach the right criminal. In this study, the Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Thermal Energy Analyser (GC-TEA) methods which are being used for the determination of the explosive materials&rsquo
residues used in bombing attacks are optimized with the standard solutions of 2,4,6-Trinitrotoluene (TNT) and 1,3,5-trinitro-1,3,5-triazocyclohexane (RDX) and standard mixture solution. The two methods were compared by analysing the postexplosion soil samples. Also an efficient and applicable sample preparation procedure was developed. The results showed that both methods are efficient and sensitive for the postexplosion investigations. It is seen that GC-TEA has lower detection limit and simple chromatograms due to its selectivity against only nitro group containing explosives. However it is concluded that there is a need for a reliable and sensitive method like GC-MS which provides identification and library search, for the determination of the organic components which can not be identified with GC-TEA

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O'Mahoney, T. Karl P. "An investigation of perfluorocarbons and bromofluorosilanes : pyrolysis, GC-ECD, GC-MS, FTIR and microwave spectroscopic studies and analysis." Thesis, University of Bristol, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259467.

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17

Jou, Kuen-Da. "Integrated analysis and pattern recognition of Swiss cheese aroma by SPME/GC, SPME/GC/MS and electronic noses /." The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487946776020555.

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Santos, Anai Loreiro dos. "Caracterização química por GC/qMS e GC×GC/TOF-MS e avaliação da atividade antioxidante dos óleos essenciais de campomanesia guazumifolia (Cambess.) O. Berg. e Piper regnellii (Miq.) C. DC." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/180653.

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O presente trabalho alia a capacidade analítica da GC×GC/TOF-MS ao uso dos índices de retenção e ferramentas adequadas de software para o estudo de óleos essenciais de Campomanesia guazumifolia (Cambess.) O. Berg. (guabiroba) e Piper regnellii (Miq.) C. DC. (pariparoba). O óleo essencial de folhas de C. guazumifolia apresentou 69 compostos tentativamente identificados, sendo o biciclogermacreno (48%), o composto majoritário. As folhas, caules e flores de P. regnellii geraram óleos essenciais com 172, 126 e 115 compostos tentativamente identificados, respectivamente. Os compostos majoritários em cada óleo essencial foram aproximadamente os mesmos, com exceção do dilapiol, que só esteve entre os majoritários no óleo essencial dos caules: o mirceno, anetol E e biciclogermacreno (22%, 19% e 5%, respectivamente, nas folhas), anetol E, dilapiol e mirceno (20%, 19% e 16%, respectivamente nos caules) e anetol E, mirceno e biciclogermacreno (24%, 18% e 9%, respectivamente nas flores). Também foi detectada atividade antioxidante moderada para os óleos essenciais das folhas, caules e flores de P. regnellii.
This work combines the analytical capability of GC × GC / TOF-MS, the use of retention indices and adequate software tools for the study of essential oils of Campomanesia guazumifolia (Cambess.) O. Berg. (guabiroba) and Piper regnellii (Miq.) C. DC. (pariparoba). The essential oil from the leaves of C. guazumifolia showed 69 compounds tentatively identified, being bicyclogermacrene (48%), the major compound. The leaves, stems and flowers of P. regnellii generated essential oils with 172, 126 and 115 compounds tentatively identified, respectively. The major compounds in each essential oil were approximately the same, except dilapiol, who was among the majority only in the essential oil of the stems: myrcene, bicyclogermacrene and anethole E (22%, 19% and 5%, respectively, in leaves), anethole E, dilapiol and myrcene (20%, 19% and 16% respectively in stems) and anethole E, myrcene and bicyclogermacrene (24%, 18% and 9%, respectively in flowers). It was also detected a moderate antioxidant activity in the essential oils of leaves, stems and flowers of P. regnellii.

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Cordes, Maik. "Entwicklung von Analysenverfahren zur Bestimmung von Antimonspezies mit EC-HG-LT-GC-AAS und HG-CT-GC-MIP-AES." [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=962076996.

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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.

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The oxidation of volatile organic compounds (VOCs) plays a role in both regional and global air quality through the formation of secondary organic aerosols (SOA). More than 1000TgC/yr of non-methane VOCs are emitted from biogenic sources (significantly greater than from anthropogenic sources). Despite this magnitude and potential importance for air quality, the body of knowledge around the identities, quantities and oxidation processes of these compounds is still incomplete (e.g., Goldstein & Galbally, 2007; Robinson et al., 2009). Two-dimensional gas chromatography paired with time-of-flight mass spectrometry (GC×GC/TOFMS) is a powerful analytical technique which is explored here for its role in better characterizing biogenic VOCs (BVOCs) and thus SOA precursors. This work presents measurements of BVOCs collected during two field campaigns and analyzed using GC×GC/TOFMS. The first campaign, the Bio-hydro-atmosphere Interactions of Energy, Aerosols, Carbon, H2O, Organics & Nitrogen - Rocky Mountain Biogenic Aerosol Study (BEACHON-RoMBAS), took place in a Ponderosa pine forest in Colorado. The second campaign, Particle Investigations at a Northern Ozarks Tower: NOx, Oxidant, Isoprene Research (PINOT NOIR) Study, was conducted in the Ozark region of Missouri. Tens to hundreds of BVOCs were quantified in each set of samples, including primary emissions, atmospheric oxidation products, stress indicators and semi-volatile leaf surface compounds. These findings highlight that there is a largely uncharacterized diversity of BVOCs in ambient samples. Our findings demonstrate that GC×GC can distinguish between compounds with the same molecular weight and similar structures, which have highly variable potentials for production of SOA (Lee et al., 2006). This work represents some of the first analysis of ambient BVOCs with this technology, which is anticipated to contribute greatly to characterization of atmospheric SOA precursors and ultimately, regional and global modeling of SOA and fine particulate matter.

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Mazollier, Aude. "Développement de méthodologies analytiques et statistiques pour le contrôle de la naturalité de matières premières pour la cosmétique et la parfumerie." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10004/document.

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Les huiles essentielles extraites de plantes aromatiques, médicinales et à parfum, sont utilisées depuis des millénaires pour leurs propriétés médicinales ou olfactives. Pour des raisons de rentabilité, les distributeurs sont contraints à réduire leur coût au maximum et à commercialiser des huiles essentielles au plus bas prix. Certains ont recours à la fraude et proposent, des essences de qualité inférieure sous la dénomination produits naturels de haute qualité. Il existe des normes (AFNOR, pharmacopées) qui doivent être respectées. Mais leur seule application est souvent limitée. Cette étude a donc permis une nette amélioration du contrôle de la naturalité des huiles essentielles de citrus, et lavande. La connaissance des compositions moléculaires des volatiles et des polymethoxyflavones (citron), l'étude énantiomérique de molécules cibles telles que l'alpha-pinène, le sabinène (citrus), le linalol et l’acétate de linalyle (bergamote et lavande), les analyses isotopiques du carbone 13, deutérium, des linalol, acétate de linalyle (bergamote et lavande), citral, acétate de géranyle (citron) ainsi que les analyses isotopiques du deutérium et azote 15 du N-méthyle anthranilate de méthyle (mandarine) sont les analyses permettant la mise en évidence de nombreux types de fraudes. Pour une méthodologie efficace, les analyses en composante principale et discriminante ont été indispensables. Elles ont permis l’identification d’échantillons fraudés via l’étude des volatiles. Les analyses chirales et isotopiques permettent l'identification d'échantillon plus “ finement ” adultérés ou de mieux comprendre les processus de fraude
Essential oils extract from aromatics, medicinal and perfume plants, are used since ancient times for their medicinal or olfactory properties. They are quite expensive, and owing to the actual growing demand for getting high quality materials at lowest prices, fraudulent essential oils are frequently found on the market. In order to fight this problem, norms exist (AFNOR, pharmacopeas) which have to be respected. However those techniques are often limited. This work allowed great improves in the quality control of citrus and lavender essential oils. The knowledge of the chemical composition of volatiles and polymethoxy-flavones (lemon), of the chirale ratios of alpha-pinene, le sabinene (citrus), linalool et linalyl acetate (bergamot et lavender), isotope ratio analyses of carbon 13, deuterium, of linalool, linalyl acetate (bergamot et lavender), citral, geranyl acetate (lemon) as wall as isotope ratio analyses of deuterium of nitrogen 15 du Nmethyl anthranilate de methyl (mandarin) permitted the detection of various type of frauds. In order to have an efficient methodology, principal component and discriminant analyses have been proved indispensables. It allowed the identification of fraudulent samples via volatiles molecules study. Chirale analysis and isotope ratio highlight frauds on more “discrete” adulterated samples or a better understanding of adulteration’s process

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LEÃO, CLÁUDIO. "Desenvolvimento e validação de metodologia para a determinação de monocloroacetato de sódio e dicloroacetato de sódio em cocoamido,N-[(3-dimetilamino)propil],betaína via cromatografia a gás: GC/FID, GC/ECD e GC/MS." reponame:Repositório Institucional do IPEN, 2016. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26796.

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Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-11-11T09:28:13Z No. of bitstreams: 0
Made available in DSpace on 2016-11-11T09:28:13Z (GMT). No. of bitstreams: 0
O monocloroacetato de sódio (MCAS) e o dicloroacetato de sódio (DCAS) são compostos tóxicos e irritantes ao ser humano e nocivos ao meio ambiente, sendo impurezas indesejáveis na cocoamido propil betaína (CAPB), que é um surfactante anfótero utilizado em produtos de consumo dos segmentos cosmético e domiciliar. Diante dos requisitos de concentração em nível de mg/kg exigidos pelos órgãos reguladores de saúde do governo, tornou-se mandatório o emprego de metodologia com limite de quantificação, precisão e exatidão adequados aos rígidos controles de processo pelos fabricantes da CAPB, bem como, dispor de técnicas convencionais com poder de resolução e proficiência pelo controle de qualidade e neste contexto inseriu-se a cromatografia a gás. Neste estudo foram estabelecidos os procedimentos analíticos que definiram as melhores condições para identificar e quantificar as impurezas MCAS e DCAS na matriz CAPB por meio da cromatografia a gás. A preparação das amostras consistiu da derivação das impurezas MCAS e DCAS a ésteres etílicos e a extração líquido-líquido em hexano para separar dos demais constituintes da matriz. Os modos de detecção acoplados à cromatografia a gás foram a ionização pela chama (GC/FID), a captura de elétrons (GC/ECD) e a espectrometria de massas (GC/MS). A validação comprovou que as metodologias são lineares entre 4 e 50 mg/kg com recuperação de 70 a 120%, apresentam limites de quantificação inferiores a 10 mg/kg e produziram médias e incertezas similares na amostra examinada, constituindo-se alternativas para a determinação de cloroacetatos em betaínas.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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23

Leão, Cláudio. "Desenvolvimento e validação de metodologia para a determinação de monocloroacetato de sódio e dicloroacetato de sódio em cocoamido,N-[(3-dimetilamino)propil],betaína via cromatografia a gás: GC/FID, GC/ECD e GC/MS." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-22082016-150806/.

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O monocloroacetato de sódio (MCAS) e o dicloroacetato de sódio (DCAS) são compostos tóxicos e irritantes ao ser humano e nocivos ao meio ambiente, sendo impurezas indesejáveis na cocoamido propil betaína (CAPB), que é um surfactante anfótero utilizado em produtos de consumo dos segmentos cosmético e domiciliar. Diante dos requisitos de concentração em nível de mg/kg exigidos pelos órgãos reguladores de saúde do governo, tornou-se mandatório o emprego de metodologia com limite de quantificação, precisão e exatidão adequados aos rígidos controles de processo pelos fabricantes da CAPB, bem como, dispor de técnicas convencionais com poder de resolução e proficiência pelo controle de qualidade e neste contexto inseriu-se a cromatografia a gás. Neste estudo foram estabelecidos os procedimentos analíticos que definiram as melhores condições para identificar e quantificar as impurezas MCAS e DCAS na matriz CAPB por meio da cromatografia a gás. A preparação das amostras consistiu da derivação das impurezas MCAS e DCAS a ésteres etílicos e a extração líquido-líquido em hexano para separar dos demais constituintes da matriz. Os modos de detecção acoplados à cromatografia a gás foram a ionização pela chama (GC/FID), a captura de elétrons (GC/ECD) e a espectrometria de massas (GC/MS). A validação comprovou que as metodologias são lineares entre 4 e 50 mg/kg com recuperação de 70 a 120%, apresentam limites de quantificação inferiores a 10 mg/kg e produziram médias e incertezas similares na amostra examinada, constituindo-se alternativas para a determinação de cloroacetatos em betaínas.
The sodium monochloroacetate (MCAS) and the sodium dichloroacetate (DCAS) are toxic and irritating compounds to humans and harmful to the environment, being undesirable impurities in cocoamidepropyl betaine (CAPB), which is a amphoteric surfactant used in consumer products of cosmetic and household segments. Considering the content requirements at level mg/kg defined by governmental health agency, became mandatory the use of analytical methods with appropriate precision, accuracy and quantification limit to rigid process controls by CAPB manufacturers, as well as, to have available conventional techniques with good resolution and proficiency for quality control staff and in this context was inserted the gas chromatography. In this study, the analytical procedures were established to define the best conditions to identify and quantify the impurities MCAS and DCAS in CAPB matrix by gas chromatography. The sample preparation consisted of MCAS and DCAS derivation to ethyl esters and liquid-liquid extraction in hexane to separate them from the other constituents of matrix. The detection modes coupled to gas chromatography were the flame ionization (GC/FID), electron capture (GC/ECD) and mass spectrometry (GC/MS). The validation ensured that the methodologies are linear between 4 and 50 mg/kg with recovery 70 to 120%, presents quantification limits less than 10 mg/kg and produced similar averages and uncertainties in the examined sample, constituting an alternative for determination of chloroacetates in betaines.

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24

Mayer, Karine Kochhann Rhoden. "Desenvolvimento e validação de método multirresíduo, empregando GC-ECD E GC-MS, para a investigação de pesticidas em morango, maçã e uva." Universidade Federal de Santa Maria, 2005. http://repositorio.ufsm.br/handle/1/10420.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico
Pesticides use is still the main strategy used in the field for the combat and the prevention of agricultural plagues, guaranteeing enough food and of quality for the population. In the culture of fruits, especially in strawberries, apples and grapes, the consequent contamination by pesticide residues has the been objective of constant concern in the ambit of the public health. Due to the toxicity associated with these substances quality of the produced victuals is necessary in order to prevent possible risks to the consumer. In the present study, a multiresidue method was developed and validated for the quantification of the pesticides chlorothalonil, chlorpyrifos, captan, procymidone, kresoxim methyl, iprodione, fenpropathrin, deltamethrin and azoxystrobine using Gas Chromatography with Electron Capture Detection (GCECD) in different matrices (strawberry, apple and grape). Gas Chromatography coupled with Mass Spectrometry (GC-MS) was used for the investigation of the pesticides present in the samples. Some extraction conditions were appraised, such as type and volume of solvents, amount of sample and purification of the extract. The extraction with 1:1 (v/v) mixture of ethyl acetate/n-hexane, in ultraturrax, followed by purification in florisil® columns and reduction of the extract volume by evaporation of the solvent presented the best results. The optimized conditions for the GC-ECD system were: capillary column DB-5; programming of the oven temperature: 80 °C - 2 min, 180 °C (10 °C min-¹)- 1 min, 255 °C (8 °C min-¹); 315 °C (15 °C min-¹) 4.25 min, pressure of the carrier gas (He) 21 psi; injection volume 1 μL; injetor temperature 270 °C and of the detector to 330 °C. For the analysis by GC-MS the used conditions were: capillary column VF - 5MS, Factor Four/MS (Varian) with 5 m of EZ-Guard®; programming of the column temperature: 80 °C (25 °C min-¹), 180 °C (5 °C min- ¹), 280 °C - 10 min, pressure of the carrier gas 10 psi; injection volume 1 μL, in the splitless mode; temperature of the manifold of 80 °C and of the interface of 230 °C, energy of 600 eV applied to the ion multiplier and ion-trap temperature of 200 °C. In the validation of the method the following parameters were verified: detection limit (LOD), quantification limit (LOQ), linearity, precision (repeatability and intermediary precision) and recovery. LODs and LOQs of the instrument varied from 2.5 to 18.7 μg L-¹ and from 5.0 to 25.0 μg L-¹, except for the deltamethrin (0.2 and 0.8 μg L-¹), respectively. For the analyzed samples obtained LOQs values from 0.6 to 15.6 mg kg-1 were obtained for the pesticides in study. The analytical solutions were prepared in "blank extract" of the fruits to compensate for the observed matrix effect, being obtained analytical curves with r2 ≥0.9925. The precision assays supplied acceptable results, with RDS values between 0.3 and 14.8%. Recoveries from 85.4 to 111.3% were obtained for the studied matrices, except for captan in grape (70.1%). The results obtained in the validation allowed us to conclude that the method is adaptable for the determination of these compounds in strawberries, apples and grapes, being that the method was applied in the analysis of 21 samples obtained in the trade. Pesticides presences were verified in 72.7% in the strawberry samples, 80% of the apple and grape samples, where chlorpyrifos, chlorothalonil, captan, iprodion, deltamethrin and fenpropathrin were found.
O uso de pesticidas é ainda a principal estratégia no campo para o combate e a prevenção de pragas agrícolas, garantindo alimento suficiente e de qualidade para a população. Na fruticultura, em especial nas culturas de morango, maçã e uva, a contaminação por resíduos de pesticidas têm sido alvo de constante preocupação no âmbito da saúde pública e da sociedade. Devido à toxicidade associada a estas substâncias o monitoramento da qualidade dos alimentos produzidos é necessário a fim de prevenir possíveis riscos ao consumidor. No presente trabalho foi desenvolvido e validado um método multirresíduo para a quantificação dos pesticidas clorotalonil, clorpirifós, captana, procimidona, cresoxim metílico, iprodiona, fenpropatrina, deltametrina e azoxistrobina empregando Cromatografia Gasosa com Detecção por Captura de Elétrons (GC-ECD) em diferentes matrizes (morango, maçã e uva). A Cromatografia Gasosa acoplada a Espectrometria de Massas (GC-MS) foi empregada para a investigação da presença de pesticidas nas amostras. Algumas condições de extração foram avaliadas, tais como tipo e volume de solventes, quantidade de amostra e purificação do extrato. A extração com mistura 1:1 (v/v) de acetato de etila/n-hexano, em ultra-turrax, seguida de purificação em colunas de florisil® e redução do volume do extrato por evaporação do solvente foi a que apresentou melhores resultados. As condições otimizadas para o sistema GC-ECD foram: coluna capilar DB-5; programação da temperatura do forno: 80 ºC 2 min, 180 ºC (10ºC min- ¹) - 1 min, 255 ºC (8 ºC min-¹); 315 oC (15 ºC min-¹) 4,25 min, pressão do gás de arraste (He) 21 psi; volume de injeção 1 μL; temperatura do injetor 270 °C e do detector a 330 ºC. Para a análise por GC-MS usaram-se as condições: coluna capilar VF- 5MS, Factor Four/MS (Varian) com 5 m de EZ-Guard®; programação da temperatura da coluna de: 80 ºC (25 °C min-¹), 180 ºC (5 ºC min-¹), 280 ºC 10 min, pressão do gás de arraste 10 psi; volume de injeção 1 μL, no modo splitless; temperatura do manifold de 80 °C e da interface de 230 °C, energia de 600 eV aplicada à multiplicadora de íons e temperatura do iontrap a 200 ºC. Na validação do método foram avaliados os seguintes parâmetros: limite de detecção (LOD), limite de quantificação (LOQ), linearidade, precisão (repetitividade e precisão intermediária) e recuperação. Os LODs e LOQs do instrumento variaram de 2,5 a 18,7 μg L-¹ e de 5,0 a 25,0 μg L-¹, exceto para a deltametrina (0,2 e 0,8 μg L-¹), respectivamente. Para as amostras analisadas obtiveram-se valores de LOQs de 0,6 a 15,6 μg kg-¹ para os pesticidas em estudo. As soluções analíticas foram preparadas em extrato branco das frutas para compensar o efeito matriz observado, obtendo-se curvas analíticas com r² ≥ 0,9925. Os ensaios de precisão forneceram resultados aceitáveis, com valores de RDS entre 0,3 e 14,8%. Recuperações de 85,4 a 111,3% foram obtidas para as matrizes estudadas, exceto para a captana (70,1%) em uva. Os resultados obtidos na validação permitiram concluir que o método é adequado para determinação destes compostos em morango, maçã e uva, sendo o método aplicado na análise de 21 amostras obtidas no comércio. Foram constatadas presenças de pesticidas em 72,7% das amostras de morango, 80% das amostras de maçã e de uva, onde foram encontrados clorpirifós, clorotalonil, captana, iprodiona, deltametrina e fenpropatrina.

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Silva, Rosselei Caiél da. "Métodos individual e multirresidual para determinação de pesticidas em grãos e derivados por GC-PFPD, GC-ITD-MS e LC-MS/MS." Universidade Federal de Santa Maria, 2011. http://repositorio.ufsm.br/handle/1/4212.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico
Due to the complexity of grains like soybean, corn and rice, and the very low pesticide concentration expected for these samples, it is really necessary to develop efficient and reliable analytical methods to identify and quantify their residues. The possibility to perform the determination of a large number of pesticides in just a single chromatographic analysis is the major advantage of the multi-residue methods. However, there are important compounds that are not possible to be analyzed together, like the dithiocarbamates (DTC). For that, is so important to develop and validate single methods. Due to low acute toxicity, combined with strong action, low-cost production and low environmental persistence, the dithiocarbamates are still using worldwide. The first part of this study reports a sensitive analytical single method suitable for the quantitative analysis of DTCs in soybeans, rice and corn, using GC-PFPD and GCITD- MS. For the method validation studies, the following parameters were assessed: detection limit (LOD), quantification limit (LOQ), precision (repeatability and intermediate precision) and accuracy, via recovery experiments at 0.05, 0.1 and 0.5 mg CS2 kg-1 spiking levels. For soybeans is necessary a clean-up step due the high fat content in that crop, because of it, same sorbents (Aluminum oxide, Florisil®, Silica, PSA, C18 and C18OH) were tested and the best results were obtained applying silica gel. For the extraction procedure, an amount of sample was weighed and water added. The spike solution (thiram) was added to the sample, 25 mL of isoctane and 150 mL of tin (II) chloride solution in hydrochloric acid were added. The bottles were closed immediately and heated for 1 h in a water bath at 80 °C, under shaking. After cooling, 2 mL aliquot of the upper organic layer of each bottle was pipetted into a tube containing 50 mg of silica gel, for the clean-up step. The analytical curves were linear from 0.02 to 1.0 mg CS2 L-1 with determination coefficients (r2) higher than 0.99 for both detection systems and to all crops. Method LOD and LOQ values were 20 and 50 μg CS2 kg-1, respectively, for soybeans and corn. For rice LOQ was just 40 μg CS2 kg-1. Very good precision was obtained with RSD between 1.8 and 7.9% and recoveries from 67 to 103%, for all matrices. The results obtained in the validation step allow us to conclude that both chromatographic detection systems are appropriate to determine residues of DTCs in grains. The second step was to develop and validate a method for the analysis of 75 pesticides in corn grain and breakfast cereals using LC-MS/MS, ESI positive mode. The extraction procedure was the modified QuEChERS method, however, excluding the dispersive SPE clean-up step. To that end, milled and homogenized corn grain and breakfast cereals with water were spiked with 75 pesticides, at 3 spiking levels (10, 20 and 50 μg kg-1, n=6), plus the procedure internal standard (quinalfos). A volume of 10 mL of acetonitrile with 1% acetic acid was added and the tubes were vigorously shaken for 1 minute. The tubes were uncapped, anhydrous magnesium sulfate were added, the shaking procedure was repeated and the extract was centrifuged at 4000 rpm, for 4 min. The upper layer of the extracts was transferred to chromatographic vial, containing 0.5 mL of the instrumental internal standard (propoxur) in methanol. The linear range wasevaluated and validated between 0.1 and 50 μg L-1 of the analytical curves (7 concentrations, n=6). Also LOD, LOQ, matrix effect, as well as precision (as RSD%) and accuracy (as recovery), for 75 pesticides, were studied The LOD were calculated based on practically realized repeatability RSD. To determine the precision, accuracy and LOQ, blank samples were spiked at 10, 20 and 50 μg kg-1. The results showed recoveries between 70 and 120% and RSDs <20% for the majority of the pesticides studied, even at the lowest level. As expected, the matrix effect did not have influence on the results, and the values of LOD and r2 were considered as satisfactory for the purpose of this study.
Devido a complexidade de matrizes de grãos como soja, milho e arroz, e das baixas concentrações dos pesticidas presentes, há uma grande necessidade de desenvolvimento de métodos analíticos eficientes e confiáveis para a identificação e quantificação desses resíduos. A maior vantagem de um método multirresidual é a possibilidade de se determinar um grande número de pesticidas na mesma análise cromatográfica. Entretanto, alguns compostos, devido suas características específicas, não podem ser determinados em conjunto com outros analitos. Assim, é importante que também se desenvolva e valide métodos individuais de análise, comoo método para determinação de ditiocarbamatos (DTC). Os DTC apresentam baixa toxicidade aguda, combinado com forte ação fúngica, baixo custo e baixa persistência ambiental, por isto, estes continuam sendo largamente utilizados na agricultura. Na primeira parte deste estudo, foi desenvolvido um método individual de análise para determinar DTC em soja, arroz e milho, empregando GC-PFPD e GC-ITD-MS. Para o estudo de validação do método, os seguintes parâmetros foram avaliados: limite de detecção (LOD), limite de quantificação (LOQ), precisão e exatidão, através do estudo de fortificação e recuperação, nas seguintes concentrações: 0,05; 0,1 e 0,5 mg CS2 kg-1. Para a determinação de ditiocarbamatos, adicionou-se um volume de água à amostra (arroz, milho e soja). Fortificou-se com solução de tiram, adicionou-se 25 mL de isoctano e 150 mL de solução de SnCl2 em HCl. Os frascos foram fechados e levados ao banho de agitação, a 80 °C, por 1 hora. Após o resfriamento, 2 mL da fase orgânica foram transferidos para outro frasco contendo 50 mg de sílica gel, para a etapa de purificação. As curvas analíticas foram lineares na faixa de 0,02 a 1,0 mg CS2 L-1, com coeficiente de determinação (r2) maior do que 0,99, para todas as culturas, nos dois sistemas de detecção. O LOD e LOQ do método apresentaram os mesmos valores para soja e milho, sendo, respectivamente, 20 e 50 μg CS2 kg-1. Já o LOQ para arroz foi de 62 μg CS2 kg-1, devido a menor quantidade de amostra utilizada. Observa-se, desta forma, que os valores de LOQ encontrados são inferiores ao limites máximos de resíduos permitidos (LMR) pela legislação nacional, que são de 0,3 mg CS2 kg-1 para soja e milho, e de 3 mg CS2 kg-1 para o arroz, indicando que os métodos podem ser utilizados para este tipo de determinação. A precisão mostrou-se muita boa, com valores de RSD entre 1,8 e 8,7%, e recuperações de 63 a 103%. Assim, os resultados obtidos pela validação do método permitem concluir que ambos os sistemas cromatográficos são adequados para determinar DTC em grãos. A segunda etapa do estudo foi validar o método multirresidual para determinação de 75 pesticidas em milho (grão) e cereais matinais, empregando LCMS/ MS, no modo ESI positivo. O procedimento de extração foi baseado no método QuEChERS, com algumas modificações. Grãos de milho e cereais matinais foram moídos e homogeneizados, e um volume de água de, respectivamente, 7,5 e 8 mL foi adicionado. Após, executou-se a fortificação com uma solução contendo os 75 pesticidas do estudo, nos níveis de concentração de 10, 20 e 50 μg kg-1. Um volume de 10 mL de solução de ácido acético 1% em acetonitrila contendo o padrão interno quinalfós foi adicionado, e os tubos agitados por 1 minuto. Os tubos foram abertos e MgSO4 anidro adicionado seguido de agitação e centrifugação a 4000 rpm, por 4 minutos. Um volume de 0,5 mL da fase superior foi transferido para vial contendo 0,5 mL do padrão interno propoxur em metanol. Os resultados obtidos para esta validação foram satisfatórios. Recuperações entre 70 e 120%, com RSD <20% foram obtidos para a maioria dos pesticidas estudados, nas duas matrizes, conforme recomendando pela SANCO (2009). Conforme esperado em LC-MS/MS, o efeito matriz não influenciou os resultados.

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26

Friggi, Caroline do Amaral. "Avaliação de um modulador a ar comprimido para gc×gc e sua aplicação para determinação de resíduos de pesticidas piretróides em uva." Universidade Federal de Santa Maria, 2008. http://repositorio.ufsm.br/handle/1/10424.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
In this study, a new modulator that is simple, robust and presents low operation costs was developed. This modulator uses compressed air to cool two small portions of the second chromatographic column of a GC×GC system. To evaluate the modulation process, solutions of alkanes C7 to C29, and pesticides (bifenthrin, cyfluthrin, cypermethrin, esfenvalerate, fenitrotion, fipronil, trifloxystrobin and trifluralin) were analyzed by GC×GC-FID. The results showed small variations of the peaks areas, between 0.67 and 2.80% for alkanes and between 0.24 and 5.34% for pesticides. The standard deviation (SD) for the retention time in the first column (1tR) was around 0.05 min, for alkanes and pesticides. For retention times in the second column (2tR), the SD was 0.04 s for the majority of the compounds, except for cyfluthrin and permethrin (0.08 s). The linear range was between 0.1 and 5.0 mg L-1 with a coefficient of determination (r2) greater than 0.9945 for pesticides analyzed by GC×GC-FID. The GC×GC system proposed was applied in the determination of pyrethroid pesticides (bifenthrin, cypermethrin, deltamethrin, fenvalerate and esfenvalerate and permethrin cis and trans) in grape samples Italy cultivar spiked at 3 levels (0.02, 0.05 and 0.5 mg kg- 1). Samples were extracted by the mini-Luke modified method (acetone method) and pesticides were quantified by GC×GC-μECD. The parameters evaluated in the validation of the method were: analytical curve, linearity, limit of detection (LOD), limit of quantification (LOQ), precision (in terms of repetitivity and intermediate precision) and accuracy (recovery), as well as the matrix effect on the chromatographic response. All analytical curves showed a linear range between 0.02 and 0.5 mg L-1 with r2 greater than 0.9956 and 0.9994 for the curves prepared in solvent (ethyl acetate) and matrix extract (grape), respectively. From the results obtained by calculation of the matrix effect percentage it can be concluded that the pyrethroid pesticides showed a considerable negative matrix effect. The values of method LOQ were 0.01 to 0.02 mg kg-1 for all pyrethroids. The values of recovery for the 3 spiked levels were between 94.3 and 115.2%, with good precision (RSD<18.4%), demonstrating that the performance of the mini-Luke modified method employed for the extractions is satisfactory. This study also showed that the GC×GC-μECD system using a modulator with a double jet of compressed air has potential for application in the analysis of pyrethroid pesticide residues in grapes, since it supplies low values of LOD and LOQ, and good accuracy in the analytical response.
Neste trabalho foi desenvolvido um novo modulador, simples, robusto e de baixo custo de operação. Este modulador utiliza ar comprimido para resfriar duas pequenas porções da segunda coluna cromatográfica de um sistema GC×GC. Para avaliar o processo de modulação utilizaram-se soluções de alcanos C7 a C29 e pesticidas (bifentrina, ciflutrina, cipermetrina, esfenvalerato, fenitrotiona, fipronil, trifloxistrobina e trifluralina) e análise por GC×GC-FID. Os resultados mostraram pequenas variações das áreas dos picos, entre 0,67 e 2,80% para alcanos e entre 0,24 e 5,34% para pesticidas. O desvio padrão (SD) para o tempo de retenção na primeira coluna (1tR) de alcanos e pesticidas foi em torno de 0,05 min. Para o tempo de retenção na segunda coluna (2tR), o SD foi de 0,04 s para a maioria dos compostos, exceto para ciflutrina e permetrina (0,08 s). A faixa linear situou-se entre 0,1 e 5,0 mg L-1 com coeficiente de determinação (r2) maior que 0,9945 para os pesticidas analisados por GC×GC-FID. O sistema GC×GC proposto foi aplicado na determinação de pesticidas piretróides (bifentrina, cipermetrina, deltametrina, fenvalerato e esfenvalerato, e permetrina cis e trans) em amostras de uva cultivar Itália fortificadas em 3 níveis (0,02; 0,05 e 0,5 mg kg-1). As amostras foram extraídas pelo método de mini-Luke modificado (método da acetona) e os pesticidas quantificados por GC×GC-μECD. Os parâmetros avaliados de validação do método foram: curva analítica, linearidade, limite de detecção (LOD), limite de quantificação (LOQ), precisão (em termos de repetitividade e precisão intermediária) e exatidão (recuperação), bem como o efeito matriz na resposta cromatográfica. Todas as curvas analíticas apresentaram faixa linear entre 0,02 e 0,5 mg L-1 com valores de r2 maiores que 0,9956 e 0,9994 para as curvas preparadas em solvente (acetato de etila) e extrato da matriz (uva), respectivamente. A partir dos resultados obtidos através do cálculo do efeito matriz percentual concluiu-se que os pesticidas piretróides avaliados apresentaram considerável efeito matriz negativo. Os valores de LOQ do método foram de 0,01 a 0,02 mg kg-1 para todos os piretróides. A recuperação para os 3 níveis de fortificação ficou entre 94,3 e 115,2%, com boa precisão (RSD<18,4%), o que mostrou que o desempenho do método mini-Luke modificado empregado para as extrações é satisfatório. Este estudo mostrou também, que o sistema GC×GC-μECD com modulador de duplo jato de ar comprimido tem potencial para aplicação nas análises de resíduos de pesticidas piretróides em uva, uma vez que fornece baixos valores de LOD e LOQ, e boa precisão da resposta analítica.

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27

Kaspar, Hannelore. "Amino acid analysis in biological fluids by GC-MS." kostenfrei, 2009. http://www.opus-bayern.de/uni-regensburg/volltexte/2009/1316/.

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28

Hamblin, D'Nisha D. "Exhaled Breath Analysis of Smokers Using CMV-GC/MS." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2605.

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The aim of this research was to demonstrate the potential of the novel pre-concentration device, capillary microextraction of volatiles (CMV), for breath analysis. The CMV offers dynamic sampling of volatile organic compounds with its simple coupling to a GC inlet for GC/MS analysis, avoiding expensive thermal desorption instrumentation needed for sorbent tubes, as well as an increased surface area over a single SPME fiber. CMV collectively identified 119 compounds in the breath of 13 self-reported smokers and 7 nonsmokers. The presence and intensity of twelve compounds were used to classify all the nonsmokers 100% of the time using Principal Component Analysis to elucidate the groupings. In some cases, nicotine was not detected in smokers and they were confused with the nonsmokers. Nicotine was detected in the breath of 69% of smokers with an average mass of 143 ± 31 pg for cigarette smokers from the approximate 5 L sample of breath collected. The successful use of the CMV sampler and preconcentration of breath to distinguish between smokers and nonsmokers served as a proof of concept for future applications of the CMV for detection of marijuana smokers’ breath for impaired driver management.

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29

Manurkar, Shaunak Sudhir. "Modular GC: A Fully Integrated Micro Gas Chromatography System." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/105044.

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Gas Chromatography (GC) is one of the most important and widely used tools in analytical chemistry. However, they are bulky, have a longer measurement cycle, and consume a high amount of power. Micro-Gas Chromatography (µGC) is portable and energy-efficient, which allows onsite, real-time biological, forensic, and environmental analyses. This thesis presents a ready-to-deploy implementation of microfabricated gas chromatography (µGC) system capable of separating complex samples. We describe robust, modular, and scalable hardware and software architecture based on Real-Time Operating System (RTOS) and Python Graphical User Interface (GUI) integrated with various microfabricated devices to realize a fully functional µGC system. A sample heater for headspace injection, microfabricated separation column (µSC), a Photoionization Detector (PI-D), and a flow controller unit are integrated with the modular hardware and software to realize a fully functional Vacuum Outlet µGC system. We have designed a novel auto-calibration method for temperature calibration of the microfabricated devices which does not require changing the electronic circuitry or reprogramming the device. The vacuum outlet µGC setup is tested with various mixture of analytes. For these experiments, an average relative standard deviation (RSD) for retention time repeatability of 2.5% is achieved. Data processing techniques for raw chromatograms, including baseline correction and peak detection, are implemented on a microcontroller board and tested extensively as a part of this work. A novel algorithm for multidimensional analysis for the identification of co-eluting compounds in complex samples is implemented with a prediction accuracy of 94%.
Master of Science
Toxic volatile organic compounds (VOCs) such as benzene and toluene found in gasoline and xylene used in ink, rubber, and leather industries are of concern as they are present at elevated concentrations due to their higher vapor pressure. Sufficient exposure to these toxicants, even at lower concentrations like 100 parts-per-billion-volume (ppbv), may cause adverse health effects. Gas Chromatography (GC) has been the established method for assessing the presence and concentration of VOCs in the environment. Traditional GC systems are bulky, power-hungry, expensive, and require expert supervision for analysis. Recent research in microelectromechanical systems (MEMS) has reduced the size of the GC components, also called micro-GC (µGC), while improving the performance. The majority of the research and development of µGC is aimed at advancing microfabricated components such as preconcentrators, separation columns, and gas detectors. However, the integration of these different components is an important topic that requires more investigation. In this thesis, we present a robust and scalable software and hardware architecture that can be used to develop a portable and modular µGC system. The thesis discusses different experiments to calibrate various microfabricated devices, which are then used to build a fully modular µGC system. We show the separation capacity of the modular µGC system by passing complex compounds like kerosene and diesel. As the chromatogram from the µGC system has noise, the second part of the thesis explores data analysis techniques such as baseline correction, peak detection. These data analysis tools are used to filter the noise, detect relevant peaks in the chromatograms, and identify the compounds in a complex sample.

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30

Garg, Apoorva. "Zebra GC: A Fully Integrated Micro Gas Chromatography System." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/64854.

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A ready-to-deploy implementation of microfabricated gas chromatography (microGC) system characterized for detecting hazardous air pollutants (HAPs) at parts-per-billion (ppb) concentrations in complex mixtures has been described. A microfabricated preconcentrator (microPC), a MEMS separation column with on-chip thermal conductivity detector (microSC-TCD), the flow controller unit, and all the necessary flow and thermal management as well as user interface circuitry are integrated to realize the fully functional microGC system. The work reports extensive characterization of microPC, microSC and micro]TCD for target analytes: benzene, toluene, tetrachloroethylene, chlorobenzene, ethylbenzene, and p-xylene. Limit of Detection (LOD) of ~1 ng was achieved, which corresponds to 10 min sampling time at a flow rate of 1 mL/min for analyte present at ~25 ppbv concentration. An innovative method for generating very sharp injection plugs from the microPC even in the presence of flow sensitive detectors like micro]TCD is described. A one-to-one comparison between microGC system and conventional Automated Thermal Desorption-Gas Chromatograph-Flame Ionization Detector (ATD GC-FID) system for real gasoline samples in simulated car refueling scenario is reported.
Master of Science

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31

Fettig, Ina Alice. "Systematische Untersuchungen zur effektiven Trennleistung von enantioselektiven GC-Phasen." Berlin mbv, Mensch-und-Buch-Verl, 2009. http://d-nb.info/998051586/04.

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32

Martel, Samile. "Comparação entre os métodos de extração quechers e miniluke modificados na extração de resíduos de pesticidas piretróides em tomate empregando GC×GC-μECD." Universidade Federal de Santa Maria, 2009. http://repositorio.ufsm.br/handle/1/10441.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
In this study, two methods frequently used in the extraction of residues of pesticides in fruits and vegetables, the QuEChERS method and the mini-Luke method, were compared in order to optimize and validate these methods using quantification by GC×GC-μECD. This study was carried out for the pesticides bifenthrin, cyfluthrin, fenpropathrin, fenvalerate, esfenvalerate and permethrin cis and trans in tomato. In the QuEChERS method, 10 mL of acetonitrile containing 1% (v/v) of acetic acid was added to 10 g of sample. In the mini-Luke method, 30 mL of acetone, followed by 60 mL of a 1:1 (v/v) mixture of petroleum ether and dichloromethane were added to 10 g of sample. In the extraction method with acetonitrile, recoveries between 90.2 and 105.5% were obtained with RSD values lower than 8.7%, whereas, using the extraction method with acetone, the recoveries were between 86.2 and 110.8% with RSD values lower than 9.0%. In terms of limit of quantification (LOQ), the QuEChERS method presented values between 0.01 and 0.02 mg kg-1, considered more satisfactory than those obtained using the modified mini-Luke method (LOQ between 0.02 and 0.05 mg kg-1), where the value of LOQ found for cyfluthrin was above of the maximum limit of residues allowed by ANVISA, and therefore unsatisfactory. The r2 values from the analytical curves in the extract of the matrix were equal or higher than 0.9992 and 0.9955 for the modified QuEChERS method and the modified mini-Luke method, respectively, demonstrating that the modified QuEChERS method supplied more appropriate r2 values. Moreover, the QuEChERS method is a simpler procedure as it utilizes manual agitation and can be employed in any laboratory or in the field. Another important advantage of this method is the lower amount of solvent used. This study also showed that the GC×GC-μECD system using a modulator of double compressed air jet reduces costs and can be used in analyses of pyrethroid pesticides in tomato, with satisfactory values of LOD and LOQ, good precision and accuracy.
Nesse estudo comparou-se dois métodos bastante utilizados na extração de resíduos de pesticidas em frutas e vegetais, o método QuEChERS e o método mini-Luke, de modo a otimizar e validar estes métodos utilizando quantificação por GC×GC-μECD. Este estudo foi realizado para os pesticidas bifentrina, ciflutrina, fenpropatrina, fenvalerato, esfenvalerato e permetrina cis e trans em tomate. No método QuEChERS adicionou-se 10 mL de acetonitrila contendo 1% (v/v) de ácido acético em 10 g de amostra. No método mini-Luke adicionou-se 30 mL de acetona, seguidos de 60 mL da mistura 1:1 (v/v) de éter de petróleo e diclorometano em 10 g de amostra. Ao empregar-se o método de extração com acetonitrila obteve-se recuperações entre 90,2 e 105,5% com RSD menor que 8,7%, enquanto que, utilizando o método de extração com acetona, as recuperações ficaram entre 86,2 e 110,8% com RSD menor que 9,0%. Em termos de limite de quantificação (LOQ) o método QuEChERS modificado apresentou valores entre 0,01 e 0,02 mg kg-1, considerados mais satisfatórios que os obtidos pelo método mini-Luke modificado (LOQ entre 0,02 e 0,05 mg kg-1), sendo que, neste caso, o valor de LOQ encontrado para ciflutrina não foi satisfatório, pois está acima do limite máximo de resíduos permitido pela ANVISA. Com relação aos valores de r2 das curvas analíticas, percebeu-se que, utilizando o método QuEChERS modificado estes valores foram maiores ou iguais a 0,9992 e para o método mini-Luke modificado foram maiores ou iguais a 0,9955, ambos para as curvas no extrato da matriz, demonstrando, portanto, que o método QuEChERS modificado forneceu valores de r2 mais apropriados. Além disso, o método QuEChERS mostrou ser um procedimento mais simples por utilizar agitação manual, podendo ser aplicado em qualquer laboratório ou a campo. Outra vantagem importante deste método é a menor quantidade de solvente utilizado. Este estudo mostrou também que o sistema GC×GC-μECD com modulador de duplo jato de ar comprimido possibilita a redução dos custos da análise e que esta combinação pode ser utilizada em análises de pesticidas piretróides em tomate, pois obteve-se valores satisfatórios de LOD e LOQ, com boa precisão e exatidão.

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33

Skinner, Michael A. "Hapsite® gas chromatograph-mass spectrometer (GC/MS) variability assessment /." Download the thesis in PDF, 2005. http://www.lrc.usuhs.mil/dissertations/pdf/Skinner2005.pdf.

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34

Asres, Daniel Derbie. "Characterization of carbohydrates using gas chromatography/mass spectrometry (GC/MS)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0001/MQ41677.pdf.

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35

RIZEL, PATRICIA. "QUALITATIVE STUDIES FOR DETERMINATION OF PYRENE METABOLITES USING GC/MS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2003. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=4329@1.

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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Os Hidrocarbonetos Policíclicos Aromáticos (HPAs) são contaminantes carcinogênicos e mutagênicos, freqüentemente encontrados no ambiente. Muitos organismos são capazes de metabolizá-los rapidamente, tornando de fundamental importância o desenvolvimento de técnicas analíticas para a determinação de seus metabólitos. A determinação do 1- hidroxipireno é considerada com uma das primeiras etapas para a avaliação do risco ambiental por exposição dos HPAs. O pireno é um dos compostos predominantes desta classe de xenobióticos e o 1-hidroxipireno é o seu principal metabólito. Neste estudo é apresentado uma método para análise qualitativa do 1-hidroxipireno. Testes foram realizados afim de viabilizar a aplicação de uma metodologia para análises de rotina em amostras biológicas. O método escolhido envolve uma etapa de hidrólise ácida com subsequente extração líquido-líquido para obtenção do 1- hidroxipireno. A cromatografia de permeação em gel (CPG) foi empregada como um método de separação de lipídios, seguida de uma etapa de cromatografia líquida de coluna aberta. Uma vez que o 1-hidroxipireno é um composto de baixa volatilidade, foi incluída uma etapa de derivação com BSTFA e seguida de análise por CG/EM.
Polycyclic Aromatic Hydrocarbons are ubiquitous pollutants that usually present carinogenic and mutagenic effects. Several organisms are able to metabolize them quickly, and therefore becoming very important the development of analytical techniques for their metabolites determination. The chemical analyses of 1-hydroxipyrene is one of the first steps for evaluation of environmental assessment by PAH exposure. Pyrene is one of the principal compounds of this xenobiotic class and 1-hydroxipyrene is yours major metabolite. This study presents a method for qualitative analysis of 1-hydroxipirene. Tests were performed due to allow the use of a methodology for routine analysis in biological samples. The chosen method included acid hydrolysis followed of liquid-liquid extraction to obtain 1- hydroxipyrene. Gel permeation chromatography (GPC) was applied as a lipid separation method, and then liquid chromatography of opened column. As long as the 1- hydroxipyrene is a low volatile compound, it was included one step of derivatization with BSTFA followed by gas chromatography/mass spectrometer (GC/MS) analysis.

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36

Song, Xiling. "Analysis of Aroma Constituents in Cultivated Strawberries by GC/MS." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/42874.

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In aroma analysis, strawberries have always been the favored fruit because of their relatively high content of typical and pleasant aroma constituents. Esters, aldehydes, alcohols and sulfur compounds have been found to be the main aroma components in strawberry. In recent years, two volatile compounds, 2,5-dimethyl-4-methoxy-3(2H)-furanone (DMF) and 2,5-dimethyl-4-hydroxy-3(2H)-furanone (DHF) were reported to contribute heavily to strawberry aroma. These two compounds have been found in all wild strawberries studied, but found only in few cultivated varieties. In this work, three kinds of cultivated strawberries were sampled and analyzed. The three strawberries all belong to the Camarosa variety. They came from different growing areas: Salinas (California), Orrville (Ohio), and Memphis (Tennessee). The volatile compounds of these three strawberries were separated by Gas Chromatography (GC), and identified by Mass Spectrometer Detector (MSD). Column and experimental conditions were optimized for this particular separation. Salinas, Orrville and Memphis strawberries have very similar aroma constituents, however, in slightly differing amounts. Several unique peaks were found in each strawberry, which may well account for the differences in the aroma qualities of the three. 2-Furaldehyde was found in both Memphis and Orrville strawberries, but not in Salinas. It is a key odor compound correlated with woody aroma and it has a low odor threshold value. These two properties make it contribute negatively to the pleasant aroma of Memphis and Orrville strawberries. A compound, 2-furanmethanol, was found only in Salinas strawberries. This compound has a faint burning aroma, however, its high odor threshold value offsets its potentially bad aroma. DMF was found in all three strawberries, but no DHF was detected in any of the three. We propose a possible explanation for the absence of DHF. Ethyl (methylthio) acetate, which is a sulfur-containing compound, was found in both Orrville and Salinas strawberries. This work is the first to report its presence in strawberries of any variety. An external standard method was employed to quantify seven main aroma components found in the strawberry extracts. Aroma values were introduced and then calculated together with sensory descriptions of these compounds. Salinas strawberry was found to have the best aroma quality of the three. These results indicate that the odors of strawberries of the same variety can be different when grown in different geographical areas.
Master of Science

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Milo, John A. "Quantitation of Halogenated Anisoles in Wine via SPME – GC/MS." Connect to resource online, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1230924488.

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Hu, Xiaoyi. "Detection and quantitation of diazinon and chlorpyrifos : a novel GC." Scholarly Commons, 2002. https://scholarlycommons.pacific.edu/uop_etds/573.

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An analytical method was developed for detection and quantitation of diazinon and chlorpyrifos, two widely used pesticides in local water pathway. Solid phase extraction combined with GC/MS detection with selected ion monitoring was employed. In establishing calibration curves for GC/MS analysis, it may be impractical to use isotope-labeled analogs as internal standards for all analytes in a complicated matrix. Compounds may have to be used as internal standards which could cause non-linear effects because of different response of analytes and internal standards. A novel sample introduction method, which could eliminate this negative effect of non-linearity, was proposed. Calibration data were acquired using the traditional constant volume injection method, and a new method: constant mass injection of analytes. Calibration curves by the constant mass injection method show a better linearity and y-intercept. The nonlinear effect observed with data obtained in low concentration ranges using the constant volume injection method was eliminated. The effectiveness of these curves by two methods was also tested. Better accuracy was obtained with the constant mass injection method. This constant mass injection of analytes method could be very useful in quantitative studies of a complicated sample matrix, such as those encountered in the environmental analysis of pesticides, or in the quality control analysis of medical and industrial product. In solid phase extraction, Varian Bondelute SPE C8 cartridge was selected for extraction. With the standard water sample spiked at 500 ng/L for the two analytes, the recovery for diazinon was about 50% and for chlorpyrifos about 60%. With the standard water sample at 1000 ng/L, the recovery for diazinon was about 60% and for chlorpyrifos about 70%. Among three samples from three different sampling sites, diazinon was detected and confirmed. The quantitation of diazinon was done to water sample from the Calaveras River near the Sanguetti Street crossing Stockton, California, with observed concentration 143.2 ng/L.

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39

Olivares, Igor Renato Bertoni. "\"Desenvolvimento, otimização e validação da técnica HS-SPME-GC/MS para análise de amostras obtidas do Rio Atibaia através da aplicação de uma sistemática \"ISO\" para diagnóstico ambiental de áreas contaminadas\"." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/75/75132/tde-16042007-171617/.

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Neste trabalho foi desenvolvida, otimizada, e validada, uma metodologia para análise de 15 pesticidas organoclorados em sedimento através de HS/SPME-GC/MS. Esta metodologia foi aplicada para análise de amostras reais visando à realização de um diagnóstico da contaminação por pesticidas organoclorados do Rio Atibaia, principalmente em sua região próxima a contaminação oriunda da empresa Shell Brasil S.A. unidade de Paulínia. Para realização deste diagnóstico, também foi desenvolvida uma metodologia padronizada para diagnóstico ambiental de áreas contaminadas, embasada principalmente em conceitos de Gestão de Qualidade e Meio Ambiente abordadas nas normas ISO 17025, ISO 14001 e GLP. Finalmente, aplicando a metodologia analítica validada, e a metodologia para realização de um diagnóstico ambiental, foi realizado o diagnóstico da presença de pesticidas organoclorados no Rio Atibaia, indicando a existência de diferentes pesticidas organoclorados em sedimento, com destaque para os compostos DDE e BHC que se encontraram em valores acima dos recomendados pela legislação canadense. Os resultados encontrados também demonstraram que as metodologias desenvolvidas foram adequadas para análise de uma contaminação real.
In this work a methodology was developed, optimized and validated for the analysis of 15 organochlorine pesticides in sediment through HS/SPME-GC/MS. This methodology was applied to the analysis of real samples for diagnosis of the organochlorine pesticides contamination of the Atibaia River, mainly in its region close the contamination from company Shell Brasil S.A. site of Paulínia. For accomplishment of this diagnosis, also a standard methodology for environmental diagnosis of contaminated areas was developed, mainly based in concepts of Quality Management and Environmental Management find in standards like ISO 17025, ISO 14001 and GLP. Finally, applying the validated analytical methodology and the methodology proposed for environmental diagnosis, the diagnosis of the organoclhorine pesticide presence in the Atibaia River was performed, indicating different organoclorine pesticides in sediment, mainly DDE and yBHC, which were found in values above of those recommended by the Canadian legislation. The results also demonstrated that the developed methodologies are adequate for analysis of a real contamination.

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40

Witrick, Katherine Amy Thompson. "Characterization of aroma and flavor compounds present in lambic (gueuze) beer." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/19203.

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Lambic beer is one of the oldest beer styles still being brewed in the western world today and the only beer that is still brewed through spontaneous fermentation. Lambic beers are only produced within a 500 km radius of Brussels because of the natural microflora found within the air in that region. Little is known about the chemical composition of lambic beers. The objective of this research were (1) to compare SPME and SAFE for the isolation of flavor and aroma compounds, (2) determine the volatile composition and acids of commercially available lambic gueuze using SPME/GC-MS and HPLC, and (3) determine the major aroma compounds of aging lambic beer using GC-O. Comparing the two extraction methods, both SPME and SAFE were able to identify a similar number of chemical compounds, however SAFE identified a greater number of acid compounds. A total of 50 compounds were identified within nine commercial brands of lambic beer. HPLC was used in the identification and quantification of acetic and lactic acids. The concentration of acetic acid in the commercial products ranged from 723 mg/L â " 1624 mg/L and lactic acid ranged from 995 â " 2557 mg/L. GC-O was used in the analysis of aged (3-28 months) lambic beer samples. As the samples increased in age, the number of aroma compounds detected by the panelists also increased. Panelists were detected nine aroma compounds in the 3 month old sample, while 17 compounds were detected in the 28 month old sample. The research conduct increased the number of volatile and semi-volatile compounds identified in lambic beer from 27 to 50.
Ph. D.

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41

Beraldo, Daniele Alves de Souza. "Desenvolvimento e validação de método analítico para análise de bisfenol A e nonilfenol em águas superficiais da cidade de Americana, SP." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/75/75135/tde-24072012-142457/.

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Neste estudo determinou-se o nonilfenol - um composto xenobiótico utilizados na fabricação de antioxidantes, aditivos para óleos lubrificantes e produção de surfactantes etoxilados - e o bisfenol A - um composto químico utilizado na produção de diversos produtos, como, plásticos policarbonatos, resinas epóxi e retardantes de chama. Ambos exibem atividade estrogênica em concentrações abaixo de 1ng L-1 - em cinco pontos de coleta na cidade de Americana, SP. Devido à ampla utilização, esses compostos estão presentes em esgoto industrial em quantidades substanciais. A primeira etapa deste estudo foi a validação dos método analítico seguindo o Método 8270D da United States Environmental Protection Agency (USEPA) que descreve o procedimento de validação para os compostos semivoláteis analisados por cromatografia gasosa acoplada a espectrometria de massas (GC/MS). Os limites de detecção e de quantificação do método para a determinação do nonilfenol foram, respectivamente, 1 e 5 µg L-1. O coeficiente de determinação (R2) e a recuperação média para o nonilfenol foram, respectivamente, 0,99 e 99,04%. Os limites de detecção e de quantificação do método para o bisfenol A foram, respetivamente, 1 e 5 µg L-1. O coeficiente de determinação (R2) e a recuperação média para o bisfenol A foram, respectivamente, 0,99 e 91,55%. Na segunda etapa desta pesquisa analisaram-se amostras de água coletadas na cidade de Americana para a determinação do nonilfenol e do bisfenol A. Como método de extração dos compostos, usou-se a extração em fase sólida (SPE) e como técnica analítica a cromatografia gasosa acoplada a espectrometria de massas (GC/MS). Os resultados indicaram a presença desses compostos em alguns pontos de amostragem sendo que a concentração do nonilfenol a variou de 5,028 a 10,524 µg L-1 e para o bisfenol A a concentração variou de 5,645 a 295,255 µg L-1. Foram feitos também testes ecotoxicólogicos utilizando como organismo teste o microcrustáceo Daphnia similis, porém o nonilfenol e o bisfenol A, na concentração testada que variou de 0,05 a 500 µg L-1 não apresentaram toxicidade aguda.
In this study it was determined nonylphenol - a xenobiotic compound used in the manufacture of antioxidants, additives for lubricating oils and production of ethoxylated surfactant - and bisphenol A - a chemical compound used in production of various products, such as polycarbonate plastic, epoxy resins and flame retardants. Both exhibit estrogenic activity at concentrations lower than 1 ng L-1 - in five sampling points in the city of Americana, SP. Due to the widespread use of these compounds, they are present in substantial quantities in industrial sewage. The first step of this study was to validate the analytical method following the Method 8270D of the United States Environmental Protection Agency (USEPA) that describes the validation procedure for semi-volatile compounds analized by gas chromatography-mass spectrometry (GC/MS). The limits of detection and quantification for determining the nonylphenol were, respectively, 1 and 5 µg L-1. The coefficient ofdetermination (R2) and recovery for nonylphenol were respectively 0.99 and 99.04%. The limits of detection and quantification for the bisphenol A were, respectively, 1 and 5 µg L-1. The coefficient of determination (R2) and recovery for bisphenol A were respectively 0.99 and 91.55%. In the second step of this study were analized in water samples of Americana city for the determination of nonylphenol and bisphenol A. As a method of extraction of the compounds it was used solid-phase extraction (SPE) and as analytical technique GC/MS. The results indicated the presence of such compounds in some sampling points and the concentration of nonylphenol ranged from 5.028 to 10.524 µg L-1 and bisphenol A concentration ranged from 5.645 to 295.255 µg L-1. Ecotoxicological tests were also performed using as test organism microcrustaceans Daphnia similis, but nonylphenol and bisphenol A, tested at concentration ranging from 0,05 to 500 µg L-1 showed no acute toxicity.

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42

Urbina, Nelson D. "A Multivariate Model for Identification of Bacteria using Pyrolysis-GC/MS." Thesis, Uppsala University, Department of Mathematics, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-122468.

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43

Taylor, Gillian. "The Application of GC-C-Irms to Biogeochemical and Bioarchaeological Investigations." Thesis, University of Newcastle Upon Tyne, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506433.

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44

Chou, Yu-chieh, and 周裕傑. "Application of vapor and liquid phase real samples by 2D-GC(GC×GC)." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/09654055638554001734.

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碩士
國立中央大學
化學研究所
100
This study consists of two objectives: one is to develop a GC x GC method with electron capture detection ( ECD ) to analyze trace levels ( ~pptv ) of atmospheric halocarbons, the other is to analyze complex liquid samples by GC x GC with flame ionization detection ( FID ). To analyze atmospheric halocarbons a self-built pre-concentrator was employed for in-line enrichment before analyzed by GC x GC – ECD. To further lower the detection limits of chlorofluorocarbon ( CFC ) replacements, oxygen doping technique was adopted for electron capture detection. The GC x GC used a valve type modulator based on the Deans switch method. Analytes after eluting from the first column were cut into slices and sent to the second column for two-dimensional separation. A commercially available software, SuferR 8, was used to process the data into three-dimensional concentration contour plots. The column combination of DB-5 x TG-1301 was found to show the best separation results for halocarbons. The correlation coefficients ( R2 ) of 2D vs. 1D results were greater than 0.9920. The reproducibility ( RSD based on N = 30 ) was better than 0.94% for all target halocarbons. The method can be used in either online or offline mode. Flask samples can be analyzed when the system is operated in off-line mode, whereas continuous monitoring is possible when the system is operated in on-line mode. As the second objective to analyze complex liquid samples, such as perfume, essential oil, wine, gasoline and biofuel, etc. the Deans switch GC x GC – FID method was tested. The column combination of DB-5 x DB-1 was found to show the optimal separation results. Rather than pursuing full separation as with the halocarbon analysis, the concept of “pattern recognition” of complex samples was adopted. A product series with minor composition variation can be distinguished based on pattern difference. This application is found particular useful where imitating products can be easily separated apart from their genuine counterparts. When compare the self-made GC x GC – FID method with the commercial GC x GC / ToF-MS method using the identical column combination, compound identification becomes possible, which further broadens the applicability of the proposed method.

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45

Dufková, Veronika. "Stanovení perfluorovaných polutantů metodou GC a GC-MS." Master's thesis, 2007. http://www.nusl.cz/ntk/nusl-369029.

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46

Tu, Yung-Feng, and 杜永鋒. "Establishing the Identification Technique of Spilled Oil by GC×GC." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/sbf4sm.

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碩士
國立聯合大學
環境與安全衛生工程學系碩士班
103
Components in oils are so complicate sometimes beyond GC-MS separation ability and thus result in co-elution chromatogram. To solve this problem, comprehensive two-dimensional gas chromatography (GC×GC) is not only an innovative technique that separates co-eluted components apart by adding a different polarity column to the end of original one, but also significantly simplify data processing procedures. This study aimed at establishing the analytical method of crude oil by GC×GC-FID. The applicability of instrument was firstly validated by comparing the results with the previous report “Establishment of the Biomarker Measuring Technologies for Offshore Oil Spills（2/2）”, and then was applied to ten crude oil samples imported from Middle-East and Africa along with a condensate originated from Taiwan in 2013. With appropriate statistical approaches and information gathered from characteristic factors such as n-C17/Pr, n-C18/Ph, 2-MN/1-MN, Pr/Ph, MDBT/mP and C29/C30, all samples were successfully distinguished associating to their origins. Furthermore two different integration methods of GC-MS were compared and discussed. Results showed that TIC and EIC methods led to totally diverse results associating with n-C17/Pr and n-C18/Ph factors. We finally concluded that EIC is a better quantitative analytical method for that TIC integrates target peak and background noise at the same time and thus acquiring larger peak value than EIC. In the future oils from lacustrine and terrestrial source rocks could be analyzed to make the database more completed since most oil samples of the study are originated from marine source rocks.

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47

Lopes, André Morgado. "Optimization of the analysis of gasolines with GC x GC." Master's thesis, 2015. https://repositorio-aberto.up.pt/handle/10216/89890.

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48

Lopes, André Morgado. "Optimization of the analysis of gasolines with GC x GC." Dissertação, 2015. https://repositorio-aberto.up.pt/handle/10216/89890.

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49

"Comparison between chromatographic, using gc-ecd, gc-fpd and gc-ms, and spectrophotometric methods to determinate dithiocarbamates in lettuce." Tese, Biblioteca Digital de Teses e Dissertações da UFSM, 2005. http://coralx.ufsm.br/tede/tde_busca/arquivo.php?codArquivo=465.

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50

wen, Shan-Shy, and 文上賢. "Comparison of Analytical Performance between Portable GC/MS and Desktop GC/MS." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/50036798931714782105.

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碩士
中原大學
化學研究所
97
Gas chromatography/mass spectrometry (GC/MS) is reliably used analytical technique for the microanalysis of organic vapor or poisonous chemical material including chemical weapons agent (CWA). In recent years poisonous disaster first respond agency and national chemical corps import new generation of GC/MS simultaneously, That are aimed at detecting and recognizing the name and the classification of poisonous chemical material at the first time, and provide analysis of damage and operational proposal for the commander, when poisonous disaster and chemical terrorism incident occurred. This research prepared benzene, disulfide carbon, acetaldehyde, acetonitrile and dichloromethane into different mixtures, and made a comparison of analyzing single reagent and mixed agent between desktop GC/MS and portable GC/MS in order to realize the difference of the analytical performance of these equipments. The result obtaired form disulfide carbon and dichloromethane determination indicated that the operators beed more skillful on analytical technique or using different columns. The main ion fragments of poisonous chemical material which are average below 45(m/z) are often ignored and therefore affect the determination of analytical technique. Obviously the separation abilioy of columns of portable GC/MS is not as good as desktop GC/MS. Using portable GC/MS to preliminary detect at first responding and then desktop GC/MS is used further to analyze the samples. Comparing sketch of portable GC/MS and desktop GC/MS could determine the classification of poisonous chemical material accurately.

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Dissertations / Theses on the topic 'GC'

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