Thesis (Ph. D.)--University of Toledo, 2008. / Typescript. "Submitted as partial fulfillment of the requirements for the Doctor of Philosophy degree in Chemistry." Includes bibliographical references (leaves 32-37, 74-75, 112-114, 155-157, 187-188, 193).

Made available in DSpace on 2014-06-11T19:29:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-10-29Bitstream added on 2014-06-13T20:59:12Z : No. of bitstreams: 1 petruci_jfs_me_araiq.pdf: 1279057 bytes, checksum: 2d09c3c4f4cf70a2e51fbf646c996c1b (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Nesse trabalho, foram desenvolvidos métodos analíticos para determinação de três classes de conservantes e contaminantes em alimentos e bebidas utilizando como técnica analítica a Eletroforese Capilar. No primeiro subgrupo, foram investigados os ânions nitrito e nitrato, utilizados como conservantes em alimentos curados. A separação foi efetuada utilizando os seguintes parâmetros instrumentais: eletrólito de corrida: 60 mmol.L-1 de borato de sódio contendo 0,2 mmol.L-1 de CTAB, pH 9,30; tensão: -10 kV, temperatura: 29º C, injeção: 8 s x 30 mbar, Capilar: 48,5 cm (sendo 40,0 cm até o detector) e detecção direta em 210 nm. Os parâmetros de validação foram investigados revelando boa precisão no tempo de migração (RSD < 0,73%). A linearidade foi estudada na faixa de 50 – 250 mg.Kg-1 para nitrito e 100 – 1000 mg.Kg-1 para nitrato, com r > 0,99. Os limites de quantificação foram de 14,8 mg.Kg-1 para nitrito e 16,9 mg.kg-1 para nitrato. A recuperação foi maior que 98% para os ânions. O método foi aplicado a amostras de alimentos encontradas no comércio local e os resultados estão abaixo dos valores permitidos pela legislação para nitrito (150 mg.kg-1 ) e nitrato (300 mg.kg-1 ). O segundo subgrupo avaliado foram os ânions benzoato, sorbato, metil e propilparabeno, que são utilizados como conservantes em diversos alimentos, dentre eles em sucos, bebidas gaseificadas, condimentos e adoçantes. As condições de separação otimizadas foram: Eletrólito de corrida: 20 mmol.L-1 de borato de sódio, tensão: 20 kV; temperatura: 29ºC, injeção: 8 s x 30 mbar; Capilar: 48,5 cm (sendo 40,0 cm até o detector) e detecção direta em 220 nm. O método foi validado, com bons resultados de precisão analítica para tempo de migração (RSD < 1,89 %), a linearidade estudada foi na faixa de 75 – 500 mg.Kg-1 , com r > 0,99 para todos os ânions. Os... / In this work were developed analytical methods for determination of three groups of preservatives and contaminants in foods and beverages using Capillary Electrophoresis. In the first group, it was investigated the nitrite and nitrate anions, used as preservatives in cured meats. The separation was achieved according to the following instrumental parameters: Running buffer: 60 mmol.L-1 sodium tetraborate containing 0.2 mmol.L-1 CTAB; voltage: -10 kV, temperature: 29ºC; injection: 8 s x 30 mbar, Capillary lenght: 48.5 cm (40.0 cm effective length) and wavelength: 210 nm. The validation parameters were investigated, revealing a good precision on the migration time (RSD < 0,73%). The linearity was evaluated in the range of 50 – 250 mg.Kg-1 to nitrite and 100 – 1000 mg.Kg-1 to nitrate (r>0.99). Limit of quantification was 14.8 mg.Kg-1 to nitrite and 16.9 mg.Kg-1 to nitrate and the recovery rate higher than 98% to these anions. The method was applied to commercial samples of meats and the obtained results were below the acceptable levels according to the Brazilian legislation (150 mg.Kg-1 to nitrite and 300 mg.Kg-1 to nitrate). The second group evaluated was the anions benzoate, sorbate, methyl and propylparaben, used as preservatives in several foods, including juices, sauces, soda and sweeteners. The analytical parameters were: running buffer: 20 mmol.L-1 sodium borate; voltage: 20 kV; temperature: 29ºC; injection: 8 s x 30 mbar; capillary: 48.5 cm (40.0 effective length), wavelength: 220 nm. The method was validated revealing a good precision (RSD > 1.89 %) and linearity in range of 75 – 500 mg.L-1 (r>0.99). Limits of detection were 27.0; 47.5; 27.0; 40.5 mg.Kg-1 ; to methylparaben, propylparaben, benzoate and sorbate, respectively. The recovery range found was from 98.81 – 104.87%. The method was applied in different commercial sodas, sweeteners, sauces and juices ... (Complete abstract click electronic access below)

Submitted in partial fulfillment of the requirements for the degree of Masters in Technology in Chemistry, M.L. Sultan Technikon, 2000. / Mycotoxins are a group of natural poisons produced by certain strains of fungal species when they grow under favourable conditions on a wide variety of different substrates. These toxins have been implicated in a wide range of acute diseases in man and animals. Their toxic effects include oesophageal cancer and liver diseases in humans, and carcinogenic effects in experimental rats and poultry. Hence, there is a need to monitor toxin levels in food commodities. / M

Este trabalho descreve a construção e avaliação de um detector condutométrico sem contato (oscilométrico) para sua aplicação em eletroforese capilar de zona e cromatografia micelar eletrocinética (MEKC). A construção do detector contou com a avaliação de diversos materiais e métodos para a confecção dos eletrodos, tão bem como o aperfeiçoamento do seu circuito eletrônico. O seu comportamento e desempenho foram verificados através do estudo dos diversos parâmetros que influenciam sua resposta, como freqüência e amplitude do sinal aplicado, temperatura e condutividade do meio. Além disso, a simulação do circuito equivalente da cela de detecção auxiliou no entendimento das propriedades do detector frente a alterações na condutividade do meio, na freqüência de operação e nas dimensões da cela. A otimização dos parâmetros operacionais foi racionalizada pela formulação de equações analíticas que descrevem o fator de resposta do detector a partir de parâmetros obtidos experimentalmente. Para o desenvolvimento do sistema de detecção, dois equipamentos completos de eletroforese capilar foram construídos. Sistemas de injeção de amostra por pressão, por gravidade, e eletrocinética foram desenvolvidos. Um dos equipamentos permite que a injeção da amostra seja feita do lado aterrado da fonte de alta tensão. Conseqüentemente, o detector é posicionado próximo do ponto de aplicação da alta tensão. Este é, de que se tem notícia, o primeiro sistema de detecção eletroquímico para eletroforese capilar com essa característica. A termostatização dos capilares foi efetuada por convecção forçada de ar. De maneira a aumentar o grau de automação e facilitar o seu manuseio, os dois equipamentos foram interfaceados a microcomputador. Os equipamentos de eletroforese com detecção oscilométrica construídos permitiram a análise de diversas substâncias em matrizes variadas, como por exemplo íons orgânicos e inorgânicos em água de chuva e material particulado, ácidos graxos de cadeia linear em gordura de coco, formaldeído na fase gasosa da atmosfera, e, pela primeira vez, espécies neutras, como álcoois alifáticos, separadas por MEKC. / This work describes the construction and evaluation of a contactless conductometric (or oscillometric) detector, for its application in capillary zone electrophoresis and micellar electrokinetic chromatography (MEKC). The materials and methods used for the construction of the electrodes, as well as the improvements on the electronic circuit, were evaluated. The behavior and performance of the detector were studied by changing the parameters that affect its response, e. g., the frequency and amplitude of the input signal, temperature and solution conductivity. The simulation of the cell equivalent electric circuit helped to understand the detector properties related to the variations in the solution conductivity, frequency, and cell dimensions. The optimization of the parameters was conducted by the formulation of analytical equations that describe the response factor using experimental data. For the detection development, two complete capillary electrophoresis equipments were constructed. Pressure, gravity, and electrokinetic sample injection systems were developed. One of the equipments allows the sample injection on the grounded side of the capillary. Consequently, the detector is placed near the high voltage application point. This is the first electrochemical detector described for capillary electrophoresis with this characteristic. The capillary thermostating was made by passing a forced air stream. Both equipments were interfaced to microcomputers. The capillary electrophoresis equipments with oscillometric detection were applied to the analysis of many types of compounds in different matrices, such as organic and inorganic ions in rainwater and particulate material, fatty acids in cocoa oil, formaldehyde in the atmosphere and, for the first time, neutral species, like aliphatic alcohols, separated by MEKC.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第16864号 / 工博第3585号 / 新制||工||1542(附属図書館) / 29539 / 京都大学大学院工学研究科材料化学専攻 / (主査)教授 大塚 浩二, 教授 松原 誠二郎, 教授 田中 勝久 / 学位規則第4条第1項該当

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The use of capillary electrophoresis (CE) has been restricted to applications having high sample concentrations because of its low sensitivity caused by small injection volumes and, when ultraviolet (UV) detection is used, the short optical path length. Sensitivity in CE can be improved by using more sensitive detection systems, or by preconcentration techniques which are based on chromatographic and/or electrophoretic principles. One of the promising strategies to improve sensitivity is solid phase extraction (SPE). Solid Phase Extraction utilizes high sample volumes and a variety of complex matrixes to facilitate trace detection. To increase the specificity of the SPE a selective solid phase must be chosen. Immunosorbents, which are a combination of an antibody and a solid support, have proven to be an excellent option because of high selectivity of the antibody. This thesis is an exploratory study of the application of immunosorbent-SPE combined with CE for trace concentration of benzodiazepines. This research describes the immobilization and performance evaluation of an immunosorbent prepared by immobilizing a benzodiazepine-specific antibody on aminopropyl silica. The binding capacity of the immunosorbent, measured as µg of benzodiazepine/ gram of immunosorbent, was 39 ± 10. The long term stability of the prepared immunosorbent has been improved by capping the remaining aminopropyl groups by reaction with acetic anhydride. The capped immunosorbent retained its binding capacity after several uses.

Despite the ongoing “war on drugs” the seizure rates for phenethylamines and their analogues have been steadily increasing over the years. The illicit manufacture of these compounds has become big business all over the world making it all the more attractive to the inexperienced “cook”. However, as a result, the samples produced are more susceptible to contamination with reactionary byproducts and leftover reagents. These impurities are useful in the analysis of seized drugs as their identities can help to determine the synthetic pathway used to make these drugs and thus, the provenance of these analytes. In the present work two fluorescent dyes, 4-fluoro-7-nitrobenzofurazan and 5-(4,6-dichlorotriazinyl)aminofluorescein, were used to label several phenethylamine analogues for electrophoretic separation with laser-induced fluorescence detection. The large scale to which law enforcement is encountering these compounds has the potential to create a tremendous backlog. In order to combat this, a rapid, sensitive method capable of full automation is required. Through the utilization of the inline derivatization method developed whereby analytes are labeled within the capillary efficiently in a minimum span of time, this can be achieved. The derivatization and separation parameters were optimized on the basis of a variety of experimentally determined factors in order to give highly resolved peaks in the fluorescence spectrum with limits of detection in the low µg/mL range.

This thesis deals with automatic bacteria genotyping by rep-PCR method. Its theoretical part presents various methods of DNA typing, basic information on electrophoresis and modern electrophoretic approaches, including their problems, misleading data distortion. In order to automate typing, there has been introduced a program for phylogenetic sample classification from rep-PCR, also applicable for data from chip capillary electrophoresis. The program consists of three main parts: digitization, bandmatching and clustering apparatus to bacterial type classification. The result of the algorithm is a phylogenetic tree, which indicates the cluster of sapmles according to bacterial type. The program has a graphical user interface for possible use in the Children's Hospital. Finally, the program is tested with data from the Children´s Hospital.

Partial Filling method (PF) and Flow Induced Dispersion Analysis (FIDA) were used for the determination of stability constants of model system of four profens (R-Flurbiprofen, S-Ibuprofen, S-Ketoprofen and S-Naproxen) complexing with β-cyclodextrin. When using PF method, only a part of capillary is filled with the selector and thus the analyte must migrate through the zone of selector first and then through the neat BGE (it has different mobilities in both zones). Dependency of the differences in migation time on the length of the selector zone is then studied. When FIDA is used, the analyte in pushed through the capillary by external pressure and dependency of the rate of peak dispersion of the analyte on the concentration of selector in capillary is observed. Moreover, PF experiments were theoretically studied by Simul 5 Complex computing programme. Values of stability constants obtained by both methods were compared with values obtained by frequently used Affinity Capillary electrophoresis (ACE) method. The comparison of stability constants values determined by PF method and FIDA shows that both investigated methods grants results comparable with those obtained by the ACE.