959 resultados para Cromatografia em fase gasosa


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Grains and legume seeds are foods that form the basis of the diets of many cultures around the world, winch contritbute to the daily nutrient requirements of humans. Vicilins (7S globulin) are storage proteins found in legume seeds, and may have an additional function constitutive defense of the embryo against pests and pathogens. In this work the vicilin from Anadenanthera macrocarpa - AmV (red-angico), was purified and partially characterized, its effect on development and larval survival and adult emergence of Callosobruchus maculatus was evaluated by determination of LD50, WD50 and ED50 in system bioassay. Purification of vicilin was initiated by the chitin affinity chromatography and then gel filtration (Superdex 75 Tricorn 10x300 mm) FPLC system followed by reverse phase chromatography (C8 phenomenex) on HPLC system. Bioassays WD50 and LD50 for larvae were 0.32% and 0.33% (w:w) respectively, since the ED50 for adults was 0.096%. The probable mechanism of action was evaluated by testing digestibility of AmV in vitro, and observed for the involvement of two fragments vicilins immunoreactive against polyclonal Anti-vicilin from Erythrina velutina (Anti-EvV) about of 22 and 13 kDa chitin binding. The AmV in its native form has been recognized by the anti-EvV, indicating that there is a conserved region in the vicilin and is probably corresponding to the chitin binding domains. These results point to a new vicilin chitin binding that can subsequently be used as a possible biopesticide protein source, in order to control insect pest C. maculatus and confirm literature findings that demonstrate vicilin in the presence of different kinds of ligands to conserved regions chitin not yet characterized

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This master thesis aims at developing a new methodology for thermochemical degradation of dry coconut fiber (dp = 0.25mm) using laboratory rotating cylinder reactor with the goal of producing bio-oil. The biomass was characterized by infrared spectroscopy with Fourier transform FTIR, thermogravimetric analysis TG, with evaluation of activation energy the in non-isothermal regime with heating rates of 5 and 10 °C/min, differential themogravimetric analysis DTG, sweeping electron microscopy SEM, higher heating value - HHV, immediate analysis such as evaluated all the amounts of its main constituents, i.e., lignin, cellulose and hemicelluloses. In the process, it was evaluated: reaction temperature (450, 500 and 550oC), carrier gas flow rate (50 and 100 cm³/min) and spin speed (20 and 25 Hz) to condensate the bio-oil. The feed rate of biomass (540 g/h), the rotation of the rotating cylinder (33.7 rpm) and reaction time (30 33 min) were constant. The phases obtained from the process of pyrolysis of dry coconut fiber were bio-oil, char and the gas phase non-condensed. A macroscopic mass balance was applied based on the weight of each phase to evaluate their yield. The highest yield of 20% was obtained from the following conditions: temperature of 500oC, inert gas flow of 100 cm³/min and spin speed of 20 Hz. In that condition, the yield in char was 24.3%, non-condensable gas phase was 37.6% and losses of approximately 22.6%. The following physicochemical properties: density, viscosity, pH, higher heating value, char content, FTIR and CHN analysis were evaluated. The sample obtained in the best operational condition was subjected to a qualitative chromatographic analysis aiming to know the constituents of the produced bio-oil, which were: phenol followed by sirigol, acetovanilona and vinyl guaiacol. The solid phase (char) was characterized through an immediate analysis (evaluation of moisture, volatiles, ashes and fixed carbon), higher heating value and FTIR. The non-condensing gas phase presented as main constituents CO2, CO and H2. The results were compared to the ones mentioned by the literature.

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O objectivo deste trabalho foi o desenvolvimento e validação de uma metodologia analítica para a determinação de clorpromazina em sangue total, tendo a protriptilina sido usada como padrão interno. A extracção e purificação dos analitos foi efectuada por extracção em fase sólida com colunas Oasis® HLB, e análise posterior por cromatografia gasosa com detector de espectrometria de massa de impacto electrónico (GC/EI-MS). Para a preparação das curvas de calibração foram fortificadas diariamente amostras de sangue branco com concentrações crescentes de clorpromazina entre 0,01 e 5 µg/mL. Foi utilizado um modelo de regressão linear, sendo os coeficientes de correlação superiores a 0,998. Os coeficientes de variação e os erros relativos foram respectivamente inferiores a 12 e 13%, cumprindo assim critérios internacionalmente aceites para a validação de métodos bioanalíticos. Foram também estudados os limites de detecção e quantificação, sendo de 3 e 10 ng/mL respectivamente. A interferência de outras substâncias foi excluída por análise de dez amostras brancas de sangue. O rendimento médio do método foi de 81%. Em virtude da sua simplicidade e rapidez, este método pode ser aplicado na determinação deste antipsicótico em amostras de sangue total, sendo adequado para análises de rotina no âmbito da toxicologia clínica e forense.

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Amicroextracção em fase sólida, SPME, é uma técnica de adsorção/dessorção desenvolvida na Universidade de Waterloo (Ontario, Canadá) que elimina a necessidade de utilização de solventes orgânicos ou instrumentos complicados para a extracção e concentração de compostos voláteis e não voláteis a partir de amostras líquidas ou gasosas.ASPME origina resultados lineares dentro de um amplo intervalo de concentrações, é compatível com qualquer tipo de equipamento de cromatografia gasosa, com colunas de enchimento ou capilares, ou ainda cromatografia gasosa-espectrometria de massa. Pode, inclusivamente ser utilizado com injectores split/splitless ou directos. Na análise de urina, sangue ou outras matrizes biológicas, a preparação das amostras é normalmente necessário extraír e concentrar os analitos de interesse, o que é efectuado com recurso à extracção líquido-líquid, extracção em fase sólida, ou outras técnicas. Estes procedimentos apresentam várias desvantagens, onde se incluem o tempo excessivo de preparação e gasto desnecessário de solventes orgânicos. A SPME elimina a maior parte destes inconvenientes, já que é uma técnica rápida e que não necessita de solventes orgânicos ou de equipamentos complicados para ser levada a cabo. Esta técnica pode ser utilizada para monitorizar analitos em amostras líquidas ou gasosas, podendo ser acoplada à cromatografia gasosa, cromatografia gasosa-espectrometria de massa ou cromatografia líquida de alta eficiência. Embora inicialmente direccionada para a determinação de compostos orgânicos no meio ambiente, as suas vantagens nas análises clínicas, forenses e de alimentos têm vindo a ser postas em evidência. Desta forma, com este trabalho pretende-se conhecer mais aprofundadamente esta técnica bem como rever as suas principais aplicações no campo da toxicologia e da química analítica.

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Neste trabalho utilizou-se a técnica de HS-SPME/GC/ITMS para o estudo qualitativo dos compostos voláteis (VOC) emitidos pelas folhas de três espécies de Eucalyptus (E.): E. citriodora, E. dunnii e E. saligna tanto em laboratório como in situ, além do estudo da relação entre folhas de eucalipto e rãs Litoria ewingi. Para este fim, foram desenvolvidos métodos análiticos. Os compostos tentativamente como (E,E)-a-farseno, (E)-4,8-dimetil-1,3,7-nonatrieno (DMNT),(E,E)-4,8,12-trimetil-1,3,7,11-tridecatetraeno (TMTT),B-cariofileno,a-cariofileno, gerrmacreno D e (E,E,E)-3,7,11,15-tetrametil-1,3,6,10,14-hexadecapentaeno (TMHP) foram encontrados no headspace de folhas picadas de eucalipto, sendo que os três primeiros também foram nas emissões áreas de E. saligna in situ, não tendo sido encontrados nos óleos voláteis das mesmas árvores, obtidos por hidrodestilação. Nas amostragens in situ, foram observados dois tipos de perfis circadianos nas emissões voláteis, incluindo compostos como cis-, trans-óxido de rosa, trans-B-ocimeno, citronelal, citronelol, entre outros. O comportamento dos compostos citados sugere que os mesmos sejam semioquímicos. Os resultados obtidos com HS-SPME (PDMS/DVB) mostraram que esta é uma ferramenta analítica relativamente simples, que preserva a vida devido ao seu caráter não invasivo, de mínima pertubação do sistema vivo sob amostragem e que, devido a sua rapidez (1 min), permite o acompanhamento de alteraçãoes rápidas provocadas por processos endógenos e/ou exógenos nos seres vivos. O monitoramento da emissão de voláteis de folhas in situ durante 8 a 10 h por vários dias consecutivos, e a extração dos voláteis de rãs vivas sob estresse, submetidas a diferentes condições de dieta e meio ambiente, exemplificam o potencial desta técnica, que abre novos horizontes na investigação de voláteis de seres vivos.

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Since the beginning of the National Program for Production and Use of Biodiesel in Brazil, in 2004, different raw materials were evaluated for biodiesel production, trying to combine the agricultural diversity of the country to the desire to reduce production coasts. To determine the chemical composition of biodiesel produced from common vegetables oils, international methods have been used widely in Brazil. However, for analyzing biodiesel samples produced from some alternative raw materials analytical problems have been detected. That was the case of biodiesel from castor oil. Due the need to overcome these problems, new methodologies were developed using different chromatographic columns, standards and quantitative methods. The priority was simplifying the equipment configuration, realizing faster analyses, reducing the costs and facilitating the routine of biodiesel research and production laboratories. For quantifying free glycerin, the ethylene glycol was used in instead of 1,2,4-butanetriol, without loss of quality results. The ethylene glycol is a cheaper and easier standard. For methanol analyses the headspace was not used and the cost of the equipment used was lower. A detailed determination of the esters helped the deeper knowledge of the biodiesel composition. The report of the experiments and conclusions of the research that resulted in the development of alternative methods for quality control of the composition of the biodiesel produced in Brazil, a country with considerable variability of species in agriculture, are the goals of this thesis and are reported in the following pages

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This dissertation aims the development of an experimental device to determine quantitatively the content of benzene, toluene and xylenes (BTX) in the atmosphere. BTX are extremely volatile solvents, and therefore play an important role in atmospheric chemistry, being precursors in the tropospheric ozone formation. In this work a BTX new standard gas was produced in nitrogen for stagnant systems. The aim of this dissertation is to develop a new method, simple and cheaper, to quantify and monitor BTX in air using solid phase microextraction/ gas chromatography/mass spectrometry (SPME/CG/MS). The features of the calibration method proposed are presented in this dissertation. SPME sampling was carried out under non-equilibrium conditions using a Carboxen/PDMS fiber exposed for 10 min standard gas mixtures. It is observed that the main parameters that affect the extraction process are sampling time and concentration. The results of the BTX multicomponent system studied have shown a linear and a nonlinear range. In the non-linear range, it is remarkable the effect of competition by selective adsorption with the following affinity order p-xylene > toluene > benzene. This behavior represents a limitation of the method, however being in accordance with the literature. Furthermore, this behavior does not prevent the application of the technique out of the non-linear region to quantify the BTX contents in the atmosphere.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Since the introduction of GC there has been an ongoing interest in reducing time of analysis resulting in new terms and definitions such as ultra fast gas chromatography (UF-GC). One of the most used definitions describes UF-GC as a technique that combines the employment of short narrow bore column with very fast temperature programming rates producing chromatographic peaks in the range of 50 ms and allowing separations times in 1-2 min or less. This paper summarizes the analytical approaches, the main parameters involved and the instrumentation towards UF-GC.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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The constant petrol fuel leak in gas stations has caused concern in many countries around the world. Those fuels have toxic organic compounds in their composition, like Polycyclic Aromatic Hydrocarbons (PAH), which are harmful to the human health. In this work the efficiency of the protection layer with a High Density Polyethylene (HDPE) membrane of 2.5 mm thickness was evaluated. The study was based in the diffusive process in the intact membrane by a permeameter developed to evaluate the diffusive process. The membrane was putted in the middle of the system to separate two sides: a local soil impregnated with diesel oil (in one side) and pure water (in the other side). The chromatography technique was conducted to evaluate the contamination in the pure water. The analyses were made monthly in a total period of 6 months of research. The results tests show that the membrane was less effective to antracene and naphthalene compounds. Despite that, the results showed that the HDPE membrane is a good alternative to prevent contamination of water and soil by the compounds under study up to one year, based on the performance in the time of study.