Orientador: Lauro Tatsuo Kubota / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-05T11:12:36Z (GMT). No. of bitstreams: 1 Torres_KarinYanetChumbimuni_D.pdf: 1133906 bytes, checksum: 36ba1bfd26d43c4e6c578a20484b0ffd (MD5) Previous issue date: 2005 / Resumo: O presente trabalho de doutorado descreve o desenvolvimento de eletrodos íon-seletivos para cálcio, potássio, sódio e cloreto em sistema de injeção em fluxo e sua aplicação para determinação simultânea em sucos de frutas, bem como o desenvolvimento de eletrodos íon-seletivos de contato sólido com baixo limite de detecção. A construção dos eletrodos íon-seletivos para os íons cálcio, potássio, sódio e cloreto foi primeiramente realizado em estado estacionário para logo ser incorporada em sistema de injeção em fluxo. A otimização de parâmetros comuns, tais como: pH, tampão, volume de injeção, vazão, entre outros, possibilitaram a realização da determinação simultânea, utilizando um arranjo de eletrodos em série. O sistema FIA potenciométrico proposto foi satisfatório para determinação simultânea destes íons em amostras de sucos, e os resultados quando comparados com os obtidos pelo método de referência foram estatisticamente iguais num nível de confiança de 95%. Em relação ao desenvolvimento de eletrodos íon-seletivos com baixo limite de detecção, quatro eletrodos diferentes foram desenvolvidos para os íons prata, chumbo, cálcio e iodeto com excelente resposta nernstiana e limite de detecção na faixa nanomolar, que foram 2 nmol L para Ag, 1 nmol L para Pb, 4 nmol L para Ca e 10 nmol L para I. Isto foi conseguido pelo uso do polímero condutor, poli(3-octiltiofeno) como interface entre o contato sólido e a membrana polimérica, o copolímero metilmetacrilato-decilmetacrilato. Os eletrodos desenvolvidos mostraram resposta rápida e boa repetibilidade, sendo promissores para sua utilização em determinações em nível de traço / Abstract: The present work describes the development of ion-selective electrodes for calcium, potassium, sodium and chloride to be employed in flow injection analyses and its application for the simultaneous determination in samples, as well as, the development of solid contact ionselective electrodes with detection limit in the nanomolar range. The preparation of ion-selective electrodes for calcium, potassium, sodium and chloride was performed optimizing them in steady-state and then incorporated in simultaneous low injection analyses. The optimization of common parameters, such as: pH, buffer, injection volume, flow, etc., was performed looking for the simultaneous determination, using an array of electrodes in series. The proposed potentiometric FIA system was satisfactory for simultaneous determination of these ions in juice samples, and the results, when compared to the reference method, were statistically the same in the 95% of confidence level. In relation to the development of solid contact ion-selective electrodes with low detection limit, four different electrodes were developed for silver, lead, calcium and iodide, with excellent nernstian response and detection limit in the nanomolar range. The obtained detection limits were 2 nmol L for Ag, 1 nmol L for Pb, 4 nmol L for Ca e 10 nmol L for I. It was possible by using the conducting polymer, poly(3-octylthiophene) as an interface between the solid contact and polymeric membrane, methyl metacrylate decyl metacrylate copolymer. The electrodes presented short response time and good repetibility, being potentially useful for determination in trace levels / Doutorado / Quimica Analitica / Doutor em Ciências

<p>This study firstly reports the development, characterisation, and application of thick-film acetylcholinesterase (AChE) biosensors based on a gold electrode modified with a mercaptobenzothiazole (MBT) self-assembled monolayer and either poly(omethoxyaniline) (POMA) or poly(2,5-dimethoxyaniline) (PDMA) in the presence of polystyrene(4-sulphonic acid) (PSSA). The Au/MBT/POMA-PSSA/AChE and Au/MBT/PDMA-PSSA/AChE biosensors were then applied to successfully detect standard organophosphorous and carbamate pesticides in a 0.1 M phosphate buffer, 0.1 M KCl (pH 7.2) solution. Secondly, it reports the construction of the Au/MBT/PANI/AChE/PVAc thick-film biosensor for the determination of certain organophosphate and carbamate pesticide solutions in selected aqueous organic solvent solutions.</p>

<p>This study firstly reports the development, characterisation, and application of thick-film acetylcholinesterase (AChE) biosensors based on a gold electrode modified with a mercaptobenzothiazole (MBT) self-assembled monolayer and either poly(omethoxyaniline) (POMA) or poly(2,5-dimethoxyaniline) (PDMA) in the presence of polystyrene(4-sulphonic acid) (PSSA). The Au/MBT/POMA-PSSA/AChE and Au/MBT/PDMA-PSSA/AChE biosensors were then applied to successfully detect standard organophosphorous and carbamate pesticides in a 0.1 M phosphate buffer, 0.1 M KCl (pH 7.2) solution. Secondly, it reports the construction of the Au/MBT/PANI/AChE/PVAc thick-film biosensor for the determination of certain organophosphate and carbamate pesticide solutions in selected aqueous organic solvent solutions.</p>

Philosophiae Doctor - PhD / This study firstly reports the development, characterisation, and application of thick-film acetylcholinesterase (AChE) biosensors based on a gold electrode modified with a mercaptobenzothiazole (MBT) self-assembled monolayer and either poly(omethoxyaniline) (POMA) or poly(2,5-dimethoxyaniline) (PDMA) in the presence of polystyrene(4-sulphonic acid) (PSSA). The Au/MBT/POMA-PSSA/AChE and Au/MBT/PDMA-PSSA/AChE biosensors were then applied to successfully detect standard organophosphorous and carbamate pesticides in a 0.1 M phosphate buffer, 0.1 M KCl (pH 7.2) solution. Secondly, it reports the construction of the Au/MBT/PANI/AChE/PVAc thick-film biosensor for the determination of certain organophosphate and carbamate pesticide solutions in selected aqueous organic solvent solutions. / South Africa

Biogeochemical changes across oceanic interfaces, and method development to study such changes, are described in this work. The interfaces studied include the Subtropical Front in the Pacific Ocean and the boundary at the base of the euphotic zone. Both interfaces are characterized by accumulations of phytoplankton, although the forcing functions that result in increased biomass are distinctly different. The Subtropical Front, located at approximately 30°N in the Pacific Ocean, was detected during a cruise in the summer of 2002 by its diagnostic 34.8 salinity outcrop, in spite of the absence of its associated temperature signature. The front displayed elevated concentrations of large diatoms; Rhizosolenia and Hemiaulus, with concentrations penetrating deeper in the water column south of the front. Rhizosolenia species were dominant on the warmer, high salinity side of the front, while Hemiaulus prevailed on the cooler, low salinity side. While high cell counts were enumerated by net tows, the elevated biomass was not visible in satellite color imagery. Size fractionated chlorophyll data revealed > 10 um cells were found below 200 m, indicating export of large cells out of the euphotic zone. This confirms observations by other investigators that fronts represent important regions of episodic export, although such export may go undetected if the biomass is not visible in ocean color images. Another region of interest was the narrow layer at the base of the euphotic zone. During stratified conditions, the layer was characterized by a fluorescence maximum, a primary nitrite maximum, and a nutricline. While fluorescence maxima have proven easy to detect using commercial fluorometers, nutrient distributions have proven more difficult. The Spectrophotometric Elemental Analysis System (SEAS) permitted detection of low concentrations of nitrite, nitrate, and phosphate with nanomolar sensitivity and 1 Hz or better sampling frequency. Using multiple wavelength spectroscopy, the range of nitrate concentrations from 2 nM to 20 uM have been detected. Profiles of nitrite obtained across the North Pacific Subtropical Gyre revealed the close correlation between nitrite and chlorophyll fluorescence maxima, suggesting that the nitrite maximum is formed by phytoplankton when insufficient light is available to permit reduction of nitrite to ammonia.