The identification and quantification of atoms, molecules, or ions concentrations in gaseous samples are in great demand for medical, environmental, industrial, law enforcement and national security applications. These applications require in situ, high-resolution, non-destructive, sensitive, miniature, inexpensive, rapid detection, remotely accessed, real time and continuously operating chemical sensing devices. The aim of this work is to design a miniature optical sensing device that is capable of detecting and measuring chemical species, compatible with being integrated into a large variety of monitoring systems, and durable enough to be used under extreme conditions. The miniature optical sensor has been realized by employing technologies from the optical communication industry and spectroscopic methods and techniques. Fused silica capillary tubing along with standard communication optical fibers have been utilized to make miniature gas sensor based on near-infrared spectroscopy for acetylene gas detection. In this work, the basic principles of infrared spectroscopy are reviewed. Also, the principle of operation, fabrication, testing, and analysis of the proposed sensor are discussed in details. / Master of Science

Le but de cette étude est de développer une méthodologie permettant d'obtenir le pH des paléofluides du système H2O-CO2-HCO3--NaCl dans leurs conditions P-T de circulation. Ceci combine une approche expérimentale pour le calibrage d'une méthode analytique, la spectrométrie Raman et une modélisation numérique pour l'interprétation quantitative des équilibres de phase ou d'espèces chimiques. Les techniques analytiques utilisées en routine pour l'étude des inclusions fluides, comme la microthermométrie et la micro-spectrométrie Raman sont utilisées pour la détermination des concentrations. Les expériences sont basées à la fois sur l'utilisation d'inclusions fluides synthétiques fabriquées dans des cristaux de quartz et sur une nouvelle méthode de synthèse de fluides dans des capillaires de silice pure. La technique des fluides contenus dans des capillaires de silice pure peut être appliquée dans une gamme de pressions, jusqu'à 2 ou 3 Kbar à température ambiante, et de températures au moins jusqu'à 400°C sous 2 Kbar de pression. Le protocole expérimental de chargement des fluides du système H2O-CO2-HCO3--NaCl et les méthodes de quantification sont élaborées et validées. La modélisation numérique est basée sur le modèle de Pitzer pour décrire la phase liquide aqueuse, en particulier les coefficients d'activité de chaque espèce chimique des espèces présentes dans la phase aqueuse. L'équation d'état de Duan est utilisée pour le calcul des propriétés P-V-T-X des phases liquide et vapeur dans le sous-système H2O-CO2-NaCl. Les conditions d'application du modèle de Pitzer dans le champ température-pression sont respectivement comprises entre 273 et 523 K et 0 et 2000 bar. La gamme de concentration en NaCl de notre modèle est comprise entre 0 et 5 molal, gamme qui correspond aux températures de fusion de la glace (Tmice) comme dernière phase. La détermination de la concentration des espèces HCO3- et CO2 est réalisée à l'aide de la micro-spectrométrie Raman et est calibrée grâce à l'utilisation des standards que sont les inclusions fluides synthétiques et la technique des capillaires de silice fondue. Un programme de calcul utilisant les modèles de Pitzer et de Duan est réalisé afin d'interpréter i) la température de fusion de la glace et la concentration en bicarbonate en termes de concentration de NaCl et ii) la température d'homogénéisation globale en termes de volume molaire global et de pression à la température d'homogénéisation. Ensuite, la spéciation du fluide est calculée le long de l'isochore à la température de piégeage si celle-ci est inférieure à 250°C. Une première application au gisement d'or de Mokrsko dans le massif de Bohême est discutée / The aim of this study is to develop the methodology to get the pH values of the palaeo-circulation in the system H2O-CO2-HCO3--NaCl in the P-T conditions of circulation. It combines the use of an experimental approach for calibrating the analytical method, Raman spectrometry, and numerical modelling for the quantitative interpretation of phase and chemical species equilibria. The routine analytical techniques for fluid inclusions are used to carry out the experimental analyses, such as microthermometry and micro-Raman spectroscopy. Experiments are based both on the use of synthetic fluid inclusions produced in quartz crystal and a new method to make synthetic fluids in fused-silica glass capillary. The synthetic fluid in silica glass capillary can be applied to a wide range of pressure (up to 2 to 3 kbar) at room temperature and temperature (as high as at least 673 K). The experimental protocol of capillary loading with different chemical species in the system H2O-CO2-HCO3--NaCl and the methods to quantify their amount are elaborated and validated. Numerical modelling is based on the use of the Pitzer model to describe the liquid aqueous phase, especially the activity coefficients of each chemical species in the liquid aqueous phase. The Duan equation of state is used for the P-V-T-X properties of the liquid and vapour phases in the simplified subsystem H2O-CO2-NaCl. The application pressure and temperature ranges of the model are respectively 273 to 523 K, and 0 to 2000 bar. Range of NaCl concentration is between 0 and 5 molal and corresponds to the range of ice melting temperature (Tmice). The determination of the concentration of aqueous species HCO3- and CO2 is performed by using micro-Raman spectrometry and is calibrated with using the standards of synthetic fluid inclusion and silica glass capillary. A software program based on the Pitzer and Duan models has been done for the interpretation of i) ice melting temperature (Tmice) and bicarbonate concentration in terms of NaCl concentration, and ii) total homogenisation temperature in terms of bulk molar volume and pressure at homogenisation temperature. Then speciation of the fluid is calculated along the isochore till the trapping temperature if lower than 250 °C. A first application to the Mokrsko gold deposit in Bohemian Massif is done and discussed

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-04-27T12:33:46Z No. of bitstreams: 1 fernandoantoniosimasvaz.pdf: 40063052 bytes, checksum: f272ddc4d930b7d243c50223436e02b2 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-05-13T13:00:49Z (GMT) No. of bitstreams: 1 fernandoantoniosimasvaz.pdf: 40063052 bytes, checksum: f272ddc4d930b7d243c50223436e02b2 (MD5) / Made available in DSpace on 2017-05-13T13:00:49Z (GMT). No. of bitstreams: 1 fernandoantoniosimasvaz.pdf: 40063052 bytes, checksum: f272ddc4d930b7d243c50223436e02b2 (MD5) Previous issue date: 2011-07-22 / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Nesta tese é descrita a preparação de novas fases estacionárias monolíticas (FEM) polimerizadas por fotoiniciação, através do método sol-gel, em capilares de sílica fundida revestidos com poliacrilato, para aplicação em eletrocromatografia capilar (ECC). Dentre as principais técnicas de separação em Química Analítica, a ECC tem despertado grande interesse no meio acadêmico, pelo fato desta combinar as vantagens tanto da cromatografia a líquido de alta eficiência quanto da eletroforese capilar. Grande parte do desenvolvimento da ECC se deve ao uso das FEM, as quais são semelhantemente aplicadas em outras técnicas cromatográficas. Ao contrário do revestimento de poliimida, amplamente empregado, o revestimento de poliacrilato, transparente acima de 370 nm e à luz visível, facilita a visualização da solução de sol no interior do capilar, o que permite controlar a injeção desta e de outras soluções, bem como observar a formação in situ da FEM. Além disso, é possível que seja feita a polimerização fotoiniciada sem a necessidade de remoção do revestimento polimérico que protege a coluna. O objetivo central deste trabalho foi entender e aprimorar o processo de fabricação das FEM para aplicações em ECC. Para isso, foram feitas modificações da câmara fotorreatora homemade utilizada para a polimerização das FEM, como uma correção na faixa espectral de trabalho de 350 a 700 nm para 350 a 400 nm; e instalação de dispositivos de segurança tanto para o operador quanto para o sistema elétrico. Para que fosse alcançado um melhor controle de injeção de fases líquidas no interior de tubos com dimensões capilares, a construção de um dispositivo de alta pressurização (DAP) que forneceu, além da pressão, grande precisão foi indispensável. O DAP, além de simples, teve ótima relação custo-benefício, comparado a modelos comerciais. O preparo das FEM foi otimizado mediante auxílio de planejamento fatorial fracionário 24-1, onde se buscou analisar propriedades eletrocromatográficas frente diferentes proporções dos reagentes empregados e tempo de incidência de luz ultravioleta (UV). Este último fator não apresentou significância e foi desconsiderado, de forma que o planejamento fosse devidamente reduzido para um planejamento fatorial completo 23, o que possibilitou uma análise mais apurada dos efeitos significativos. O fator mais influente foi a proporção de porogênio (tolueno), sendo que a melhor condição obtida foi utilizando 80,0 % (v/v) de solução porogênica; 3,5 % (m/m) de fotoiniciador óxido de bis(2,4,6-trimetilbenzoil)-fenilfosfino (Irgacure 819); razão molar água/ metacriloxipropiltrimetoxisilano (MPTMS) igual a 4 e tempo de incidência de luz UV de 10 minutos. As características morfológicas, espectroscópicas e porosidade foram avaliadas através de microscopia eletrônica de varredura, infravermelho e porosimetria por adsorção de nitrogênio, respectivamente. As FEM foram testadas em ECC pela separação de hidrocarbonetos policíclicos aromáticos (naftaleno, acenafteno, fluoreno, fenantreno e antraceno) e alquilbenzenos (etilbenzeno, propilbenzeno, butilbenzeno e hexilbenzeno), todos compostos eletricamente neutros, diluídos em metanol (1 mmol L-1 cada), utilizando tiouréia como marcador de fluxo. Como fase móvel foi utilizada a mistura de acetato de amônio 16,7 mmol L-1 pH 7,0 (60 %) e acetonitrila (40 %). A voltagem aplicada foi -20 kV; a temperatura de análise foi 20 ºC; a injeção dos analitos foi -25 mbar por 5 s; e a detecção no UV foram nos comprimentos de onda de 220 nm e 250 nm. Foi utilizado o modo ECC-rápida, que consiste na inversão do sentido de análise e injeção de padrões pela extremidade curta do capilar. Este modo se mostrou muito mais rápido, repetitivo e eficiente do que o modo normal, fornecendo em pouco mais de 12 minutos de análise, mais de 51400 pratos/m de coluna e desvios padrão relativos em tempo de migração/retenção entre 0,09 e 3,3 % e em área de pico relativa entre 0,14 e 1,6 %. Os perfis de separação em ECC corroboraram com os resultados de porosidade e morfologia obtidos. / This thesis describes the preparation of new monolithic stationary phases (MSP) polymerized by photoinitiation through sol-gel approach in polyacrylate-coated fused silica capillary, for application in capillary electrochromatography (CEC). CEC has been concentrated much attention among the major separation techniques in analytical chemistry because it combines the advantages of both high performance liquid chromatography and capillary electrophoresis. Much of the CEC development is due to the use of MSP, which are similarly applied to other chromatographic techniques. Unlike polyimide-coating, widely used, the polyacrylate-coating, which is transparent above 370 nm and visible, enables the visualization of the sol solution within the capillary, allowing one to control the injection of sol and other solutions, in addition to observe the in situ formation of the MSP. Furthermore, it is possible to perform the photoinitiated polymerization without removing this polymeric coating that protects the capillary. The main purpose of this work was to comprehend and improve the fabrication process of MSP, for CEC applications. For this, some changes were set in the homemade photo reactor chamber, used for the MSP polymerization, like correction in the work range from 350 – 700 nm to 350 – 400 nm; and installation of security devices for both operator and electric system safeties. For better control of liquid phases injection within tubes with capillary dimensions, the build of a high-pressure device (HPD) that provides a great precision, in addition to the high-pressure, was essential. HPD is simpler and relatively cheaper when compared to commercial models. The preparation of the MSP has been optimized through assistance of a 24-1 fractional factorial design, with the intention to investigate electrochromatographic properties with different amounts of employed reagents and ultraviolet (UV) light incidence time. The later factor did not show significance and was unconsidered, making the design possible to be reduced to a 23 complete factorial design, which allowed analyzing the significant effects accurately. The most influent factor was the porogen (toluene) proportion, and the best condition was obtained using 80.0 % (v/v) of porogenic solution; 3.5 % of photoinitiator bis(2,4,6 trimetylbenzoyl)-phenylphosphine oxide (Irgacure 819); water to metacryloxypropyltrimethoxysilane (MPTMS) molar ratio equal to 4 and 10 minutes of UV light incidence time. The MSP morphological, spectroscopic characteristics and porosity were evaluated through scanning electron microscopy, infrared spectroscopy and nitrogen adsorption porosimetry, respectively. The MSP has been tested in CEC through the separation of polycyclic aromatic hydrocarbons (naphthalene, acenaphthene, fluorene, phenanthrene and anthracene) and alkylbenzenes (ethylbenzene, propylbenzene, butylbenzene and hexylbenzene), which are electrically neutral compounds, after dilution in methanol (1 mmol L-1 each), using thiourea as the flow marker. As mobile phase a mixture of ammonium acetate 16.7 mmol L-1 at pH 7.0 (60.0 %) and acetonitrile (40.0 %) was used. The applied voltage was -20 kV, the temperature of analysis was 20 °C, the analyte injection was -25 mbar for 5 s, and UV detection was done at 220 and 250 nm. A fast-CEC mode, which consists to reverse the analysis direction and to introduce the analyte by capillary short-end injection, was performed. This mode was much more fast, repetitive and efficient than the normal one, providing in a little more than 12 minutes over than 51400 plates per meter of column and relative standard deviations ranging from 0.09 to 3.3 % for migration/retention time and from 0.14 to 1.6 % for relative peak area. The separation profiles in CEC corroborate with the porosity and morphology results.