• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 16
  • 15
  • 8
  • 3
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 67
  • 23
  • 21
  • 18
  • 15
  • 14
  • 13
  • 13
  • 12
  • 11
  • 10
  • 9
  • 9
  • 8
  • 8
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Otimização e validação de metodologia para quantificação de trihalometanos em águas / Optimization e validation of methodology for quantification of trihalomethanes in water

Carlos, Elenice Aparecida 24 September 2002 (has links)
Submitted by Reginaldo Soares de Freitas (reginaldo.freitas@ufv.br) on 2016-09-27T18:24:50Z No. of bitstreams: 1 texto completo.pdf: 293428 bytes, checksum: 94ac90797c34ea5d83942b040244763e (MD5) / Made available in DSpace on 2016-09-27T18:24:50Z (GMT). No. of bitstreams: 1 texto completo.pdf: 293428 bytes, checksum: 94ac90797c34ea5d83942b040244763e (MD5) Previous issue date: 2002-09-24 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / O cloro é um agente desinfetante amplamente empregado no tratamento de águas destinadas ao consumo humano com o objetivo de eliminar agentes patogênicos e evitar a ocorrência de doenças que colocariam em risco a saúde da população. Mesmo sendo um processo indiscutivelmente vantajoso, a cloração tem o inconveniente de gerar, como subprodutos, os trihalometanos (THM’s). Estes compostos apresentam potencial carcinogênico e a quantidade máxima permitida em águas potáveis é estabelecida por legislação específica. Neste trabalho otimizou-se uma metodologia de extração e quantificação dos quatro principais THM’s em água: clorofórmio, bromodiclorometano, dibromoclorometano e bromofórmio. Para extrair os THM’s das amostras de água, foi empregada a técnica de extração por “headspace”, que consiste em aquecer a amostra, contida em um frasco hermeticamente fechado, provocando a volatilização destes compostos que se concentram na parte superior do frasco. Uma alíquota da fase gasosa é injetada em um cromatógrafo a gás equipado com detector de captura de elétrons (DCE). Alguns fatores que influenciam a extração dos THM’s foram avaliados e a técnica de extração otimizada. Os fatores avaliados foram: temperatura de aquecimento, tempo de equilíbrio após o aquecimento e volumes da fase gasosa - coletado e injetado. A quantificação dos THM’s por cromatografia gasosa foi também otimizada após avaliar diferentes colunas cromatográficas, fluxo do gás de arraste e programação de temperatura da coluna. A metodologia de extração e quantificação dos THM’s foi validada estabelecendo a faixa de trabalho, linearidade de resposta, limites de detecção e quantificação, precisão e exatidão. A precisão do método foi estudada sob condições de repetibilidade, reprodutibilidade e também sob condições intermediárias a estas. A reprodutibilidade do método foi avaliada em estudo interlaboratorial em que amostras de água tratada foram analisadas por dois outros laboratórios (CETEC e COPASA). O método de extração e quantificação otimizado mostrou-se adequado, com parâmetros de precisão, limites de detecção e quantificação, faixa de trabalho e linearidade de resposta e exatidão comparáveis a outros métodos. Apresenta ainda, em relação aos demais, a vantagem de ser mais barato e não necessitar do emprego de solventes orgânicos, de fases estacionárias para extração em fase sólida ou “purge-and- trap” e de fibras de microextração em fase sólida. Nas amostras de água coletadas na região do Município de Viçosa – M.G. foram detectados, além do clorofórmio, THM’s bromados, em níveis abaixo do valor máximo permitido pela legislação brasileira que é de 100 μg L-1. A origem dos THM’s bromados está associada à presença de brometo na água bruta. Na tentativa de determinar o nível de contaminação deste ânion na água bruta foi proposto um método espectrofotométrico baseado na metodologia padrão. O método modificado foi também otimizado e seus resultados comparados com o método padrão, apresentando a vantagem de empregar agente oxidante mais estável e barato. / Chlorine is a disinfectant agent widely used in the treatment of water meant for human consummation, with the purpose of eliminating pathogenic agents and thus preventing the occurrence of diseases that could put at risk the health of the population. Although indisputably an advantageous process, chlorination has the disadvantage of generating, as subproducts, trihalomethanes (THM’s). These compounds presents carcinogenic potential and the maximum permissible contents is established by specific legislation. In this investigation a method of extraction and quantification for the four main THM’s in water was optimized: chloroform, bromodichloromethane, dibromochloromethane and bromoform. To extract the THM’s from the water samples, the headspace method was employed, that consists in heating a sample contained in hermetically closed vessel provoking the volatibilization of these compounds that concentrates in the upper part of the vessel. An aliquot of gaseous phase is injected in a gas chromatograph equipped with a electron capture detector (ECD). Some of the factors influencing the extractions of the THM’s were evaluated and the extraction method optimized. The evaluated factors were: heating temperature, equilibrium time after heating, and the volumes of the gaseous phase collected and injected. The quantification of the THM’s by gas chromatography was also optimized after evaluating different chromatographic columns, flow of carrying gas and column temperature programming. The THM extraction and quantification methodology was validated by establishing the working range, linearity of response, limits of detection and quantification, precision and accuracy. The precision of the method was studied for conditions of repeatability, reproducibility and also for intermediate conditions. The reproducibility of the method was evaluated by means of an inter laboratory study in which the treated water was analyzed by two other laboratories (CETEC and COPASA). The optimized extraction and quantification method was found to be adequate, with precision, limits of detection and quantification, working range and linearity of response and accuracy parameters comparable to the other methods. Also, in comparison with the other methods, it has the advantage of being less expensive and not needing organic solvents, stationary phases for solid phase extraction or purge- and-trap, and fibers for solid phase microextraction. In the water samples collected in the region of Viçosa county, state of Minas Gerais, Brazil, besides chloroform, brominated THM’s were detected, in levels below the maximum limits allowed by brazilian legislation, which is 100 μg L-1. The origin of these brominated THM’s is associated with the presence of bromide in the gross supply water. In an attempt to determine de contamination levels of this anion in the gross water supply, a photo spectrometric method was proposed, based on the standard method. The modified method was also optimized and the results compared to the standard method, having the advantage of using cheaper and less expensive oxidizing agents.
12

Application of Non-Targeted Volatile Metabolomics in Plant Pathology

She, Jinyan 08 December 2017 (has links)
Our study focuses on the application of volatile metabolomics and chemometrics in plant pathology. Specifically, volatile metabolites or volatile organic compounds (VOCs) from the American chestnut tree (Castanea dentata) and its pathogenic fungus Cryphonectria parasitica have been investigated. The American chestnut was once a dominant tree species in the eastern forests of the United States. However, it was nearly devastated by the fungal pathogen C. parasitica. The loss of this tree species has significantly impacted the ecosystem. Therefore, preservation and restoration of American chestnut are crucial. Chapter one provides an overview of mass spectrometry based volatile metabolomics and their implementation in the investigation of plant pathology. The study of volatile metabolites profiles from virulent and hypovirulent strains of C. parasitica are presented in chapter two. The microbial volatile organic compounds (MVOCs) profiles were analyzed via nondestructive sampling method, headspace solid phase microextraction (HS-SPME), combined with gas chromatography (GC)-mass spectrometry (MS). The results indicate that the MVOCs profiles emitted from these two strains are significantly different. In general, compared with its hypovirulent strains, high emissions of sesquiterpenes were observed in the virulent strains. Furthermore, the study explored MVOCs differences associated with hypovirulence processes. The study found that both hypovirulence and aging can alter the virulent strains' MVOCs, and the process can be observed via their volatile metabolites. Chapter three describes the effects of aging, cultivation medium, and pH on fungal volatile metabolite profiles, all of which can change the strength of MVOCs emission and their composition. An acidic environment favors fungal bioactivity and therefore enhanced MVOCs emission. However, due to the inherently low MVOCs production from hypovirulent strains, the pH effect was less apparent in the hypovirulent isolates. The strength of MVOCs emission was highly correlated to the fungal expansion in virulent strains for the first 14 days. The overall emission from hypovirulent strains was relatively steady during the 28-day observation. Finally, the cultivation media are critical to the fungal MVOCs production. Among the tested media, cornmeal was least favorable for MVOCs production for both strains. Finally, Chapter Four presents a study of the total constitutive phenolic content estimation and volatile organic compounds identification from four species of chestnut tree leaf tissues. Folin Ciocalteu reagent assay with UV/Vis spectrophotometry was applied to estimate the total phenolic content in leaf tissues of American chestnut (Castanea dentata), Chinese chestnut (Castanea mollissima), and their backcross breeding generations (B3F2 and B3F3). The results from leaf tissue extraction in methanol/water (95:5 v/v), pH 2, and analyzed under the UV/Vis at 765 nm show that the variations among these tree species are significant (ANOVA, p < 0.05). The kinetics of phenolic compound solid-liquid extraction was elaborated using Peleg, second order, and power law models. Moreover, the analysis of VOCs collected from these species indicated that the distinction of American and Chinese chestnut could be archived via their VOCs, while the hybrids’ leaf VOCs are different from their parents’.
13

The Effect of Wine Matrix Ingredients on 3-Alkyl-2-methoxypyrazines Measurements by Headspace Solid-Phase Microextraction (HS-SPME)

Hartmann, Peter J. 15 April 2003 (has links)
The effect of wine matrix ingredients and conditions on the headspace (HS) sampling of 3-alkyl-2-methoxypyrazines was investigated with solid-phase microextraction (SPME) and capillary gas chromatography, using a nitrogen phosphorus detector. Changes in the recovery of 3-ethyl-, isopropyl-, sec-butyl-, and isobutyl-2-methoxypyrazines from the static headspace of synthetic wine matrices spiked with 5mg/L of each analyte were investigated and reported as a function of SPME fiber type, extraction time, and temperature. The influence of pH, ethanol, phenolics, and ground oak was studied. DVB/Carboxen?/PDMS SPME fibers at an extraction temperature of 50°C for 30 minutes with 30% (w/v) added sodium chloride resulted in the highest analyte recoveries. Although, PDMS (100 micron) SPME fibers at an extraction temperature of 35°C for 30 minutes with 30% (w/v) added sodium chloride resulted in the lower analyte recoveries, the fiber remained functional after 50 to 75 analyses after other coatings deteriorated. Changing the sample ethanol concentration from 0 to 20% (v/v) resulted in an exponential decrease in the recovered analytes. Below pH 2, there was extensive loss of the analytes in the headspace. No measurable impact on alkylmethoxypyrazine headspace concentrations was observed with exposures to selected phenolics and to ground oak. / Master of Science
14

Determinação de clorobenzenos em água por cromatografia de fase gasosa com headspace / Determination of chlorobenzenes in water by gas chromatography headspace

Margarida Maria Sartori Tavares 29 February 2012 (has links)
As preocupações com o meio ambiente em particular com a água, adquirem especial importância, porque as demandas estão se tornando cada vez maiores, sob o aspecto crescente da população e das atividades industriais. Quando se fala em água subterrânea, a primeira ideia que surge é que ela seja potável. Mas nem sempre isso é uma verdade. Em área urbana, os crescentes números de problemas devido a contaminação, na maioria das vezes por vazamentos de combustíveis oriundos dos tanques de armazenamento dos postos de gasolina. Sem falar nas indústrias que também oferecem potencial risco de contaminação para esses corpos hídricos e são pouco divulgadas. O presente trabalho tem como foco determinar os compostos clorobenzenos por cromatografia de fase gasosa com headspace (CG-HS) em matriz água e validar a metodologia. A metodologia usada neste estudo foi cromatografia de fase gasosa com headspace (CG HS), por ser uma técnica excelente e sensível e é utilizada para determinar compostos voláteis em baixas concentrações. Os dados obtidos foram tratados estatisticamente de modo avaliar a seletividade, os limites de detecção e quantificação, a faixa linear de trabalho, a linearidade e a recuperação. As recuperações variam de 80 a 110%, os coeficientes de variação obtidos foram menor que 20%, todas as substâncias estudadas apresentaram linearidade na faixa de trabalho de 0,8 a 100g.L-1. Foram estudadas 10 amostras de água subterrânea do Município do Rio de Janeiro e nas amostras analisadas foram encontrados todos os compostos em estudo, com faixa de concentração: monoclorobenzeno (<0,8 a 2,988g.L-1); 1,3-diclorobenzeno (<0,8 a 23,067g.L-1); 1,4-diclorobenzeno (nd a 16,160g.L-1); 1,2-diclorobenzeno (<0,8 a 48,685g.L-1); 1,3,5-triclorobenzeno (<0,8 a 21,900g.L-1); 1,2,4-triclorobenzeno (1,007 a 183,808g.L-1) e 1,2,3-triclorobenzeno (<0,8 a 126,886g.L-1) / The concerns with the environment, in particular with water, acquire special importance, because the demands become ever higher, under the growth of the population and industrial activities aspects. When speaking about underground water, the first notion that comes to mind is that it is potable water. But thats not always a true. In urban areas, the increasing numbers of problems due to contamination, is caused, most of time, by leaking gas tanks of gas stations. Not to mention industries that also offer the potential risk of contamination of these water bodies and that less divulged. The present work is focused in determining chlorobenzenes by headspace gas chromatography (HS-GC) in the water and validating its methodology. The methodology used in this work was headspace gas chromatography (HS-CG), because of its excellence technique and sensitive, applied for determining low concentrations volatile compounds. The data was statistically treated so to evaluate the selectivity, quantitation and detection limits, work range linearity, linearity and recovery. The recoveries vary between 80 to 110%, the variation obtained were less than 20%, all compounds present linearity in the work range 0,8 of 100g.L-1. . Ten samples of underground water of Rio de Janeiro were tested, and all the samples contained the studied compounds, as and range concentration: chlorobenzene (<0,8 a 2,988g.L-1), 1,3-dichlorobenzene (<0,8 a 23,067g.L-1), 1,4-dichlorobenzene (nd a 16,160g.L-1), 1,2-dichlorobenzene (<0,8 a 48,685g.L-1), 1,3,5-trichlorobenzene (<0,8 a 21,900g.L-1), 1,2,4-trichlorobenzene (1,007 a 183,808g.L-1) and 1,2,3-trichlorobenzene (<0,8 a 126,886g.L-1)
15

Determinação de clorobenzenos em água por cromatografia de fase gasosa com headspace / Determination of chlorobenzenes in water by gas chromatography headspace

Margarida Maria Sartori Tavares 29 February 2012 (has links)
As preocupações com o meio ambiente em particular com a água, adquirem especial importância, porque as demandas estão se tornando cada vez maiores, sob o aspecto crescente da população e das atividades industriais. Quando se fala em água subterrânea, a primeira ideia que surge é que ela seja potável. Mas nem sempre isso é uma verdade. Em área urbana, os crescentes números de problemas devido a contaminação, na maioria das vezes por vazamentos de combustíveis oriundos dos tanques de armazenamento dos postos de gasolina. Sem falar nas indústrias que também oferecem potencial risco de contaminação para esses corpos hídricos e são pouco divulgadas. O presente trabalho tem como foco determinar os compostos clorobenzenos por cromatografia de fase gasosa com headspace (CG-HS) em matriz água e validar a metodologia. A metodologia usada neste estudo foi cromatografia de fase gasosa com headspace (CG HS), por ser uma técnica excelente e sensível e é utilizada para determinar compostos voláteis em baixas concentrações. Os dados obtidos foram tratados estatisticamente de modo avaliar a seletividade, os limites de detecção e quantificação, a faixa linear de trabalho, a linearidade e a recuperação. As recuperações variam de 80 a 110%, os coeficientes de variação obtidos foram menor que 20%, todas as substâncias estudadas apresentaram linearidade na faixa de trabalho de 0,8 a 100g.L-1. Foram estudadas 10 amostras de água subterrânea do Município do Rio de Janeiro e nas amostras analisadas foram encontrados todos os compostos em estudo, com faixa de concentração: monoclorobenzeno (<0,8 a 2,988g.L-1); 1,3-diclorobenzeno (<0,8 a 23,067g.L-1); 1,4-diclorobenzeno (nd a 16,160g.L-1); 1,2-diclorobenzeno (<0,8 a 48,685g.L-1); 1,3,5-triclorobenzeno (<0,8 a 21,900g.L-1); 1,2,4-triclorobenzeno (1,007 a 183,808g.L-1) e 1,2,3-triclorobenzeno (<0,8 a 126,886g.L-1) / The concerns with the environment, in particular with water, acquire special importance, because the demands become ever higher, under the growth of the population and industrial activities aspects. When speaking about underground water, the first notion that comes to mind is that it is potable water. But thats not always a true. In urban areas, the increasing numbers of problems due to contamination, is caused, most of time, by leaking gas tanks of gas stations. Not to mention industries that also offer the potential risk of contamination of these water bodies and that less divulged. The present work is focused in determining chlorobenzenes by headspace gas chromatography (HS-GC) in the water and validating its methodology. The methodology used in this work was headspace gas chromatography (HS-CG), because of its excellence technique and sensitive, applied for determining low concentrations volatile compounds. The data was statistically treated so to evaluate the selectivity, quantitation and detection limits, work range linearity, linearity and recovery. The recoveries vary between 80 to 110%, the variation obtained were less than 20%, all compounds present linearity in the work range 0,8 of 100g.L-1. . Ten samples of underground water of Rio de Janeiro were tested, and all the samples contained the studied compounds, as and range concentration: chlorobenzene (<0,8 a 2,988g.L-1), 1,3-dichlorobenzene (<0,8 a 23,067g.L-1), 1,4-dichlorobenzene (nd a 16,160g.L-1), 1,2-dichlorobenzene (<0,8 a 48,685g.L-1), 1,3,5-trichlorobenzene (<0,8 a 21,900g.L-1), 1,2,4-trichlorobenzene (1,007 a 183,808g.L-1) and 1,2,3-trichlorobenzene (<0,8 a 126,886g.L-1)
16

O aroma das flores de Passiflora spp na atração de polinizadores : uma abordagem bioquímica e molecular / Role of the Leafy (LFY) gene in two species of Passiflora

Cutri, Lucas, 1983- 18 February 2013 (has links)
Orientador: Marcelo Carnier Dornelas / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-22T02:41:48Z (GMT). No. of bitstreams: 1 Cutri_Lucas_D.pdf: 2714790 bytes, checksum: 166e8f9c13b78486aa747c098642efc0 (MD5) Previous issue date: 2013 / Resumo: O gênero Passiflora é representado por lianas e pequenos arbustos que totalizam cerca de 600 espécies. As flores deste gênero possuem uma série de inovações fisiológicas e morfológicas, que possibilitam a adaptação a diferentes tipos de polinizadores. Os compostos voláteis que compõem o aroma destas flores contribuem para o sucesso reprodutivo destas espécies, uma vez que atuam na atração de polinizadores específicos. Os constituintes voláteis emitidos pelas flores são em sua grande maioria lipofílicos com baixo peso molecular e pertencem a diferentes classes de metabólitos vegetais. O objetivo deste trabalho foi analisar os componentes voláteis presentes no aroma de três espécies de Passiflora com diferentes síndromes de polinização: melitofilia, ornitofilia e quiropterofilia (Passiflora edulis, P. coccinea e P. mucronata, respectivamente). As análises foram realizadas utilizando técnicas de micro extração em fase sólida (SPME) associada à cromatografia gasosa e espectrometria de massas (GC-MS). Os resultados sugerem diferenças no padrão de substâncias voláteis detectas no "headspace" floral das espécies P. edulis e P. coccinea e P. mucronata. P. aedulis possui como componentes voláteis majoritários os benzenóides metoxilados provenientes da via dos fenilpropanóides; P. coccinea possui principalmente terpenóides e P. mucronata possui terpenóides, alcanos, derivado de ácido graxo e substância contendo enxofre. No banco de etiquetas de seqüências expressas (ESTs) de tecidos reprodutivos de P. edulis (PASSIOMA) foram encontradas seqüências similares a genes relacionados à via de biosbiossíntese de componentes voláteis. Destes, PePAL e PeOMT, potencialmente envolvidos na produção de benzenóides metoxilados, que também são encontrados em outras espécies vegetais polinizadas por insetos, tiveram seus padrões de expressão analisados em tecidos de flores de P. edulis por RT-PCR quantitativa ou semi-quantitativa e por hibridização in situ. Os resultados sugerem que a via de fenilpropanóides está ativa em tecidos florais de P. edulis potencialmente envolvidos na emissão de voláteis, especialmente no tecido epitelial da corona, o qual apresenta características ultraestruturais de células secretoras. O trabalho corrobora com a observação de diferença no padrão de componentes voláteis em flores de Passiflora, e apresenta dois genes candidatos envolvidos na produção de uma classe de metabolitos especializados em P. edulis / Abstract: The genus Passiflora comprises more than 600 species of lianas and small shrubs. The typical flowers of Passiflora congregate a series of morphological and physiologic innovations that allow adaptation to a number of pollinating agents. The volatile compounds present in the flower scent ("headspace") are important features to the effective reproduction of plant species since they act in the attraction of the correct pollinating agent. These compounds emitted by flowers are basically of low-molecular weight, mostly lipophilic and are represented by very different chemical classes. The aim of this work was the analysis of the volatile compounds present in the floral "headspace" of three different Passiflora species pollinated by bees, hummingbirds and bats (Passiflora edulis, P. coccinea and P. mucronata, respectively). Solid phase micro extraction (SPME) coupled to GC-MS analysis was the analytical tool in that study. The results showed different patterns of volatile compounds in the floral "headspace" of P. edulis, P. coccinea and P. mucronata. The "headspace" of P. edulis contained phenylproanoids mostly represented by methylated benzenes, P. coccinea, terpenes and P. mucronata terpenes, alkanes, fatty acid derivative, and sulphur-containing compounds. Genes potentially involved with the synthesis of key enzymes of volatile compounds pathways were identified in an Expressed Sequence Tag (EST) database obtained from reproductive tissues of P. edulis (PASSIOMA). Among these PePAL and PeOMT possibly involved with the production of methylated benzenes that acting in the insect attraction in different plant species. PePAL and PeOMT had their expression patterns analyzed by quantitative and semi-quantitative RT-PCR as well as by in situ hybridization. This approach confirmed that the phenylpropanoid pathway is active in flowers of P. edulis, especially in the epithelial tissue in corona filaments that has ultra-structural features of secretor cells. This work emphasizes the chemical differences in scent flower among Passiflora species, and shows two genes potentially involved in scent flowers production in P. edulis / Doutorado / Biologia Vegetal / Doutor em Biologia Vegetal
17

Determinação de canabinóides em cabelo por microextração em fase sólida por Headspace e análise por espectrometria de massa associada à cromatografia em fase gasosa / Determination of cannabinoids in hair by Headspace solid-phase microextraction and gas chromatography-mass spectrometry

Oliveira, Carolina Dizioli Rodrigues de 21 July 2005 (has links)
Foi desenvolvido um método para determinar canabinóides (canabidiol, canabinol e delta-9-tetraidrocanabinol) no cabelo. Uma amostra de 10mg foi descontaminada com diclorometano, seguida de digestão alcalina, microextração em fase sólida por headspace (HS-SPME) e analisada por espectrometria de massa associada à cromatografia em fase gasosa (GC/MS). Os limites de detecção e de quantificação foram de 0,07 e 0,12 ng/mg, respectivamente, para todos canabinóides estudados. O método demonstrou ser simples, rápido, preciso e linear no intervalo de 0,12 a 12 ng/mg (r2 > 0,98). Amostras de cabelo de 8 usuários de Cannabis foram coletadas de pacientes provenientes de uma clínica dependentes pela equipe médica. O método mostrou-se eficiente em amostras de cabelos de usuários que faziam uso da droga pelo menos 10 vezes por semana. / A method was to develop to detect cannabinoids (cannabidiol, cannabinol and delta-9-tetrahydrocannabinol) in hair. A 10 mg of hair sample was descontaminated by dichloromethane followed by alkalin digestion, headspace solid-phase microextraction technique (HS-SPME) and analyzed by gas chromatography-mass spectrometry (CG/MS). The detection and quantitation limits were 0,07 and 0,12ng/mg respectively for all studied cannabinoids. The method proved to be simple, fast, precise and linear at the range of 0,12 to 12ng/mg (r2 > 0,98). Eight hair samples of Cannabis user were collected from patients at admittance from a dependence clinic by clinical staff. The method showed efficient in samples of users who use the drug at least 10 fold a week.
18

Determinação de canabinóides em cabelo por microextração em fase sólida por Headspace e análise por espectrometria de massa associada à cromatografia em fase gasosa / Determination of cannabinoids in hair by Headspace solid-phase microextraction and gas chromatography-mass spectrometry

Carolina Dizioli Rodrigues de Oliveira 21 July 2005 (has links)
Foi desenvolvido um método para determinar canabinóides (canabidiol, canabinol e delta-9-tetraidrocanabinol) no cabelo. Uma amostra de 10mg foi descontaminada com diclorometano, seguida de digestão alcalina, microextração em fase sólida por headspace (HS-SPME) e analisada por espectrometria de massa associada à cromatografia em fase gasosa (GC/MS). Os limites de detecção e de quantificação foram de 0,07 e 0,12 ng/mg, respectivamente, para todos canabinóides estudados. O método demonstrou ser simples, rápido, preciso e linear no intervalo de 0,12 a 12 ng/mg (r2 > 0,98). Amostras de cabelo de 8 usuários de Cannabis foram coletadas de pacientes provenientes de uma clínica dependentes pela equipe médica. O método mostrou-se eficiente em amostras de cabelos de usuários que faziam uso da droga pelo menos 10 vezes por semana. / A method was to develop to detect cannabinoids (cannabidiol, cannabinol and delta-9-tetrahydrocannabinol) in hair. A 10 mg of hair sample was descontaminated by dichloromethane followed by alkalin digestion, headspace solid-phase microextraction technique (HS-SPME) and analyzed by gas chromatography-mass spectrometry (CG/MS). The detection and quantitation limits were 0,07 and 0,12ng/mg respectively for all studied cannabinoids. The method proved to be simple, fast, precise and linear at the range of 0,12 to 12ng/mg (r2 > 0,98). Eight hair samples of Cannabis user were collected from patients at admittance from a dependence clinic by clinical staff. The method showed efficient in samples of users who use the drug at least 10 fold a week.
19

Vývoj, optimalizace a validace analytické metody na stanovení těkavých mastných kyselin ve vodných vzorcích metodou GC/MS

OPEKAR, Jan January 2018 (has links)
This thesis is focused on the development of an analytical method for the determination of volatile fatty acids in aqueous samples using GC-MS/MS. The theoretical section provides general information on a selected group of acids, their significance in the biogas plants, the means of their derivatization and the analytical techniques used. The practical part mainly deals with optimizition of various parameters in the derivatization reaction to achieve optimal conditions. Finally, the analytical method was successfully validated and applied to the analysis of a real sample.
20

Développement de supports absorbants à base de cyclodextrines pour la désodorisation des atmosphères de travail par des essences naturelles / Development of absorbent substrates based on cyclodextrins for the deodorization of working atmospheres by natural essences

Ciobanu, Anca 15 December 2011 (has links)
L’objectif de cette thèse était de réaliser des désodorisants, obtenus à partir de différentes essences naturelles. Ceux-ci doivent être efficaces dans l’amélioration du microclimat des atmosphères de travail. Une étude fondamentale sur l'optimisation de l'extraction des essences naturelles et l'identification des composants de ces essences a été réalisée par GC/MS. Nous avons étudié également les processus de reconnaissance moléculaire entre les composants majoritaires de ces essences et des CDs natives ou modifiées. La stabilité de ces complexes a été mesurée par trois méthodes différentes : l’headspace statique, la spectrophotométrie UV-visible et la microcalorimétrie de titration isotherme. La réalisation d’adsorbants à base de cyclodextrines a été effectuée en utilisant des polymères de cyclodextrine synthétisés à partir de l’épichlorhydrine ainsi que des matériaux hybrides de type CM-β-CD/LDH. L’efficacité des désodorisants obtenus a été évaluée en mesurant la durée de libération des composés odorants. / The objective of this thesis was to develop air fresheners from various natural essences. Those must be efficient in the improvement of working atmosphere microclimate. A fundamental study on the optimization of extraction of natural essences andidentification of components of these essences was performed by GC/MS. We have also studied the process of molecular recognition between the major components of these essences and native or modified CDs. The stability of these complexes was measured by three different methods: static headspace, UV-visible spectrophotometry and isothermal titration microcalorimetry.The realization of adsorbents supports based on cyclodextrins was carried out by using cyclodextrin polymers synthesized from epichlorohydrin and hybrid materials of CM-β-CD/LDH type. The efficiency of air fresheners was evaluated by measuring the release time of odorous compounds.

Page generated in 0.065 seconds