Thèses : « Qualitative Analytic Chemistry »

1

Asimopoulos, George. « Hartley transform based algorithm for the qualitative and quantitative analysis of multi-component mixtures with the use of emission excitation matrices ». Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-06062008-171404/.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

2

Menegotto, Morgana. « Avaliação da degradação biótica do poli(ácido lático), do polipropileno e suas misturas pela ação de fungos basidiomicetos ». reponame:Repositório Institucional da UCS, 2014. https://repositorio.ucs.br/handle/11338/887.

Texte intégral

Résumé :

Resíduos poliméricos, quando destinados em ambientes inadequados, associados a sua resistência à degradação, podem promover poluição ambiental. Desta forma, estudos que possibilitam favorecer a degradação de alguns polímeros vêm crescendo e são considerados como alternativa para os atuais problemas de poluição ambiental. Outra alternativa que possibilita alterar características de interesse dos polímeros é por meio do desenvolvimento de misturas poliméricas, sendo que suas propriedades físicas e químicas podem ser alteradas para uma vasta gama de aplicações, proporcionando desempenho desejável ao produto final. Neste trabalho foi desenvolvida misturas poliméricas entre o polipropileno (PP), polímero sintético, e o poli(ácido lático) (PLA), polímero biodegradável com e sem a presença de agente compatibilizante (AC) a base de PP modificado com anidrido maleico. O objetivo do trabalho foi avaliar as propriedades da mistura de PLA e PP sem e com a presença de agente compatibilizante, bem como a ação de 10 fungos asidiomicetos isolados dos biomas mata atlântica e pampa na degradação individualmente dos polímeros e da mistura de PLA/PP. As misturas poliméricas foram produzidas por processo de extrusão e injeção e verificadas as propriedades morfológicas, térmicas, químicas e mecânicas. Para o processo de degradação biológica em cultivo sólido in vitro foram produzidos filmes de PP, PLA e suas misturas, por moldagem por compressão. Os polímeros puros foram submetidos à exposição aos 10 fungos por períodos de 14, 28 e 75 dias a 28°C sendo os fungos Trametes villosa (Sw.) Kreisel 82I.6, Schizophyllum cf. commune (Fr.) 85E.16 e Auricularia bull Ex. Juss. 551.9B os que proporcionaram indícios de degradação nos filmes de PLA e o fungo T. villosa (Sw.) Kreisel 82I.6 nos filmes de PP. A mistura de PLA/AC/PP (75/3/25) selecionada por apresentar maior caráter hidrofílico, foi submetida à exposição ao fungo T. villosa (Sw.) Kreisel 82I.6 por 14, 28 e 60 dias a 28°C. Após o período avaliado, foram verificadas as propriedades físicas (perda de massa), morfológicas (microscopia ótica e microscopia eletrônica de varredura) e características químicas (espectroscopia no infravermelho com transformada de Fourier). Como resultados das propriedades das misturas, estas mostraram-se imiscíveis e as propriedades mecânicas foram inferiores as do PLA, sem alteração da estabilidade térmica e mudança da hidrofilia com o aumento de PP. O PLA diminuiu sua cristalinidade após o processamento e o PP aumentou. Foram produzidos extratos em cultivo líquido do PLA com os fungos T. villosa (Sw.) Kreisel 82I.6, S. cf. commune (Fr.) 85E.16 e A. bull Ex. Juss. 551.9B e do PP com o fungo T. villosa (Sw.) Kreisel 82I.6, contudo as enzimas não foram eficientes quanto a degradação biológica nos caldos. Os fungos que apresentaram maior potencial de degradação em cultivo sólido do PLA foram o T. villosa (Sw.) Kreisel 82I.6, S. cf. commune (Fr.) 85E.16 e A. bull Ex. Juss 551.9B e para o PP foi o fungo T. villosa (Sw.) Kreisel 82I.6; evidenciado na colonização da superfície com remoção de material após 28 e 75 dias de incubação. O fungo T. villosa (Sw.) Kreisel 82I.6 utilizado no processo de degradação em cultivo sólido da mistura PLA/AC/PP (75/3/25) propiciou que fosse identificado indícios de degradação nos períodos estudados.
Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2015-02-20T16:07:37Z No. of bitstreams: 1 Dissertacao Morgana Menegotto.pdf: 4833989 bytes, checksum: 9e911dfa8cf78af6b06ea5d15a320088 (MD5)
Made available in DSpace on 2015-02-20T16:07:37Z (GMT). No. of bitstreams: 1 Dissertacao Morgana Menegotto.pdf: 4833989 bytes, checksum: 9e911dfa8cf78af6b06ea5d15a320088 (MD5)
Bolsa de Desenvolvimento Tecnológico e Inovação
Polymeric wastes when intended improperly, associated with its resistance to degradation may promote environmental pollution. Therefore, studies involving the degradation of some polymers are considered as an alternative to current environmental pollution problems. Another alternative that allows changing the characteristics of interest of the polymers is through the development of polyblends, and their physical and chemical properties can be changed to a wide range of applications, providing desirable performance to the final product. In this work were used polypropylene (PP), synthetic polymer, and polylactic acid (PLA), biodegradable polymer with and without the presence of compatibilizer (AC) based maleic anhydride modified PP. The objective of this study was to evaluate the properties of the blend of PLA and PP with and without the presence of compatibilizer as well the action of 10 basidiomycete fungi isolated from biomes, rainforest and pampa in as individually degradation polymers and the blends of PLA/PP. Polyblends of PP and PLA with and without the presence of a compatibilizer were produced by extrusion and injection process and morphological analysis, thermal, chemical and mechanical properties. For the process of biological degradation in solid culture in vitro were produced films of PP, PLA and their blend by compression molding. The pure polymers were subjected to exposure to the ten basidiomycete fungi for a period of 14, 28 and 75 days at 28°C, being the fungi Trametes villosa (Sw.) Kreisel 82I.6, Schizophyllum cf. commune (Fr.) 85E.16 and Auricularia bull Ex. Juss. 551.9B those who have provided evidence of degradation in the films of PLA and the fungus T. villosa (Sw.) Kreisel 82I.6 in the films of PP. A blend of PLA/AC/PP 75/3/25 selected due to its higher hydrophilic character, was subjected to exposure to the fungus T. villosa (Sw.) Kreisel 82I.6 during 14, 28 and 60 days at 28°C. After the evaluation period the physical properties (weight loss), morphological (light microscopy and scanning lectron microscopy) and chemical characteristics (infrared spectroscopy with Fourier transform) were observed. As a result of the properties of the blends, these proved to be immiscible, and the mechanical properties were lower than those of the PLA, without change in thermal stability and change in hydrophilicity with PP increasing. PLA decreased crystallinity after processing and PP increased. The solutions produced in liquid culture of the PLA with fungi T. villosa (Sw.) Kreisel 82I.6, S. cf. commune (Fr.) 85E.16 and A. bull Ex Juss. 551.9B and PP with the fungus T. villosa (Sw.) Kreisel 82I.6, however, the enzymes were not as efficient biological degradation in the broth. The fungi that showed higher degradation potential in solid culture of PLA were the T. villosa (Sw.) Kreisel 82I.6, S. cf. commune (Fr.) 85E.16 and A. bull Ex. Juss 551.9B below those reported in the literature time and the PP, the fungus T. villosa (Sw.) Kreisel 82I.6.; it promoted surface changes with removal of material after 28 and 75 days of incubation. The fungus T. villosa (Sw.) Kreisel 82I.6 used in the process of degradation in solid culture blend PLA/AC/PP (75/3/25), was identified that provided evidence of degradation during periods of exposure this study.

Styles APA, Harvard, Vancouver, ISO, etc.

3

Mahuteau, Laurent. « Study of algorithms for analysis of xrf spectra to automate inspection of carpets ». Thesis, Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26625.

Texte intégral

Résumé :

The objective of this thesis is to categorize carpet types according to their XRF spectra and verify if further classification of carpets is possible for use of an XRF analysis system in the carpet manufacturing line. This thesis consists of (1) implementing and studying effective algorithms for automated analysis of X-ray spectra, (2) comparing known algorithms for X-ray spectra analysis, and (3) implementing our own algorithm for classification of carpets spectra obtained for further fluorine online analysis of XRF inspected carpets. This research is intended for quick and accurate automated analysis of raw XRF spectra and matching analysis results to a database of XRF spectra of raw carpets. The research uses spectrum signal processing and spectrum analysis regarding efficacy of combined methods for XRF inspected carpets. X-Ray Fluorescence is a key technology for detection of chemical elements. Fluorine is a key element for carpet's quality. XRF has been chosen to be a potential candidate to measure fluorine since it is a versatile tool for low concentration element detection. Due to specific XRF background spectrum for each different carpet type, carpet samples may need specific calibrations for further computation of carpet fluorine concentration. Automating the detection of the carpet type is intended to help in automating the XRF calibration.

Styles APA, Harvard, Vancouver, ISO, etc.

4

Calloni, Caroline. « Jabuticaba (Plinia trunciflora (O. Berg) Kausel) : composição química, atividade antioxidante in vitro e redução do etresse oxidativo/nitrosativo via modulação da função mitocondrial em cultura de fibroblastos humanos (MRC-5) ». reponame:Repositório Institucional da UCS, 2014. https://repositorio.ucs.br/handle/11338/882.

Texte intégral

Résumé :

A jabuticaba (Plinia sp.), uma fruta nativa do Brasil, tem despertado grande interesse científico devido ao seu conteúdo de fitonutrientes e seus benefícios a saúde, sendo considerada um alimento funcional. Estudos demonstraram que a jabuticaba é rica em compostos fenólicos, principalmente antocianinas e flavonóis. Esses compostos vêm sendo relacionados à redução da incidência de doenças que apresentam o estresse oxidativo e nitrosativo em sua fisiopatologia, como doenças cardiovasculares, diabetes e o câncer. Recentemente, estudos têm demonstrado que a disfunção mitocondrial está presente como um fator determinante no desenvolvimento e progressão do estresse oxidativo e nitrosativo e que compostos fenólicos teriam a capacidade de regular essa disfunção. Neste contexto, o objetivo deste trabalho foi avaliar a composição de macronutrientes, o conteúdo de compostos fenólicos totais e antocianinas da casca e da polpa de jabuticaba (P. trunciflora). Paralelamente, determinou-se a composição química do extrato de casca de jabuticaba (ECJ), através de espectrometria de massas, e a sua atividade antioxidante in vitro através dos ensaios de DPPH• e ABTS•+. Além disso, avaliou-se a capacidade do ECJ em reduzir o estresse oxidativo/nitrosativo e modular a função mitocondrial, a qual foi determinada através da atividade do complexo I da cadeia de transporte de elétrons e da biossíntese de ATP, na linhagem celular de fibroblastos de pulmão humano (MRC-5) tratados com H2O2. Os resultados demonstraram que o principal macronutriente presente tanto na casca quanto na polpa da jabuticaba são carboidratos. A casca apresentou maior conteúdo de fibras totais em relação à polpa. Além disso, os compostos fenólicos apresentaram-se em maior quantidade na casca da jabuticaba, sendo que a maior parte destes compostos encontrados na casca são antocianinas. A análise de espectrometria de massas do ECJ permitiu a identificação de cianidina-3-O-glicosideo, canferol, ácido hexadecanóico e ácido octadecanóico. O ECJ apresentou atividade antioxidante in vitro nos dois ensaios utilizados. Nas células MRC-5 o ECJ foi capaz de evitar significativamente a diminuição da atividade do complexo I da cadeia de transporte de elétrons e atenuou a diminuição na biossíntese de ATP induzida pelo H2O2. Concomitantemente, o ECJ foi capaz de minimizar o aumento da peroxidação lipídica, os níveis de óxido nítrico e a perda da viabilidade induzida pelo H2O2 nas células MRC-5. Estes dados mostram, pela primeira vez, a capacidade do ECJ em reduzir danos oxidativos/nitrosativos via modulação da função mitocondrial em células de mamíferos. Além disso, esses achados representam um avanço em relação ao entendimento dos mecanismos de ação dos compostos fenólicos e colaboram como uma alternativa para o desenvolvimento de possíveis tratamentos de doenças que apresentam a disfunção mitocondrial e o estresse oxidativo/nitrosativo em sua fisiopatologia.
Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2015-02-12T12:25:33Z No. of bitstreams: 1 Dissertacao Caroline Calloni.pdf: 2384035 bytes, checksum: b09d76eb830be7e315d9a2479fa5b6fc (MD5)
Made available in DSpace on 2015-02-12T12:25:33Z (GMT). No. of bitstreams: 1 Dissertacao Caroline Calloni.pdf: 2384035 bytes, checksum: b09d76eb830be7e315d9a2479fa5b6fc (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Jaboticaba (Plinia sp.), a native fruit from Brazil, has attracted scientific interest due to its phytonutrient content and potential health benefits, and therefore it has being considered a functional food. Studies have shown that jaboticaba is a rich source of phenolic compounds, mainly anthocyanins and flavonols. Phenolic compounds are natural products that hold important biological activities and have been reported to reduce the incidence of disease associated with oxidative and nitrosative stress in their pathophysiology, such as cardiovascular diseases, diabetes and cancer. Recent studies have shown that mitochondrial dysfunction is a key factor in development and progression of oxidative and nitrosative stress. Moreover, studies have observed the ability of phenolic compounds to modulate mitochondrial function. Thus the aim of this study was to evaluate the macronutrient composition, the total phenolic content and anthocyanins content in jaboticaba (P. trunciflora) peel and pulp. Simultaneously, it was determined the chemical composition of the jaboticaba peel extract (JPE) by mass spectrometry, and its in vitro antioxidant activity through the DPPH• and ABTS•+ assays. The ability of JPE to reduce oxidative/nitrosative stress and modulate mitochondrial function, assessed by complex I activity and ATP biossintesis, in human lung fibroblasts cells (MRC 5) challenged with H2O2 were also determined. Results evidenced that the majority of macronutrients present in both peel and pulp are carbohydrates. Jaboticaba peel showed higher fiber content than the pulp. Phenolic compounds are also present in higher quantity in the peel, and almost all phenolic compounds present in the peel are anthocyanins. Mass spectrometry analysis of the JPE allowed the identification of cyanidin-3-O-glucoside, kaempferol, hexadecanoic acid and octadecanoic acid compounds. The JPE presented in vitro antioxidant activity, through DPPH• and ABTS•+ assays. In MRC-5 cells, JPE was able to prevent the decrease in complex I activity and attenuated the decrease in ATP levels induced by H2O2. The ECJ was also able to minimize the increased in lipid peroxidation and nitric oxide levels, and prevented the cell viability loss induced by H2O2. These results show for the first time, the ability of JPE to reduce oxidative/nitrosativos damage via modulation of mitochondrial function in mammalian cells. Furthermore, these findings represent an advance over the understanding of the mechanisms of action of phenolic compounds and collaborate as an alternative for the development of potential treatments for diseases with mitochondrial dysfunction and oxidative/nitrosative stress in their pathophysiology.

Styles APA, Harvard, Vancouver, ISO, etc.

5

Garcia, Charlene Silvestrin Celi. « Salvia officinalis (Lamiaceae) Lin. : caracterização química, atividade citotóxica e apoptótica em células de mamíferos ». reponame:Repositório Institucional da UCS, 2014. https://repositorio.ucs.br/handle/11338/880.

Texte intégral

Résumé :

Salvia officinalis (Lamiaceae), conhecida popularmente como sálvia, tem sido muito utilizada no sul do Brasil como condimento nos alimentos, tintura hidroalcoólica e chá para o tratamento de vários distúrbios de saúde. As propriedades dessa planta são estudadas por apontar possíveis mecanismos de ação antioxidante e antitumoral. Neste trabalho, o extrato hidroalcoólico e aquoso de sálvia foram analisados quimicamente por meio de cromatografia gasosa acoplada a espectrômetro de massas (GC-MS) e electrospray de alta resolução acoplada a espectrômetro de massas (ESI-QTOF MS/MS) em modo negativo. A identificação química mostrou a presença de ácidos como caféico, rosmarínico, málico, succínico, tartárico, cítrico, ursólico e compostos como luteolina-7-O-glucoronide, eucaliptol, β-tujona, β-cariofileno, α-cariofileno, α- tujona, cânfora viridiflorol, mannol, rosmanol e seus isômeros metilcarnosato e ácido 12-metoxicarnosinico. Os extratos apresentaram compostos polifenólicos com capacidade de varrer os radicais 2,2-difenil-1-picrilhidrazil (DPPH•) e 2,2’- azino-bis(3-etilbenzotiazolina-6-ácido sulfônico) (ABTS•+), além de atividade catalase (CATlike) e superóxido dismutase (SOD-like). Ambos os extratos apresentaram menor citotoxicidade em linhagens não tumorais (HeK-293 e MRC-5) e seletividade para linhagens tumorais (Hep-2, HeLa, A-549, HT-29, A-375 e HepG2). Além disso, verificou-se que o aumento do tempo de exposição ao extrato hidroalcoólico diminuiu a viabilidade em linhagens tumorais. Foram observadas alterações morfológicas por coloração de Giemsa e a avaliação da apoptose com anexina V e iodeto de propídeo mostraram a maioria das células tumorais em estágios finais do processo de apoptose e necrose após 24h de tratamento em ambos os extratos. Sugere-se que o extrato de Salvia officinalis (L.) possui atividade biológica em células tumorais, podendo ser objetivo de mais estudos com a finalidade de comprovar sua eficácia como possível agente para o tratamento do câncer.
Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2015-02-12T12:00:17Z No. of bitstreams: 1 Dissertacao Charlene Silvestrin Celi Garcia.pdf: 2151872 bytes, checksum: 7bfd73bdf5fd152982466e3f75044d21 (MD5)
Made available in DSpace on 2015-02-12T12:00:17Z (GMT). No. of bitstreams: 1 Dissertacao Charlene Silvestrin Celi Garcia.pdf: 2151872 bytes, checksum: 7bfd73bdf5fd152982466e3f75044d21 (MD5)
Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul, FAPERGS
Salvia officinalis (Lamiaceae), popularly known as sage, has been used in south of Brazil as a condiment in foods, as tincture and tea for the treatment various health disorders. The properties of this plant have been studied and suggest possible mechanisms of antioxidant and antitumor action. Here, the sage hydroalcoholic and aqueous extract were chemically analyzed by gas chromatography-mass spectrometry (GC-MS) and by high-resolution electrospray ionization mass spectrometry (ESI-HRMS) in negative mode. The chemical identification showed the presence of acids as caffeic, rosmarinic, malic, succinic, tartaric, citric, ursolic and compouns like luteolin-7-O-glucoronide, eucalyptol, β-thujone, β-caryophyllene, α-caryophyllenen and α-thujone, camphor, viridiflorol, mannol, rosmanol and its isomers methylcarnosate and 12-methoxycarnosinic acid. The extracts showed the content of polyphenolic compounds, ability to scavenge the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH•) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+), moreover catalase (CAT-like) and superoxide dismutase (SOD-like) activity. Both extracts showed lower cytotoxicity in non-tumor lines (HEK-293 and MRC-5) and selectivity for tumor cell lines (Hep-2, HeLa, A-549, HT-29, A-375 e HepG2). Furthermore, it was found that increasing the treatment exposure time of the hydroalcoholic extract decreases the tumor cell viability. Morphological changes by giemsa were observed and staining for annexin V and propidium iodide showed majority of tumor cells at late stages of the apoptotic process and necrosis after 24h treatment with both extracts. The results of this study suggest that the extract of Salvia officinalis (L.) has biological activity against tumor cell and may be the objective of further studies in order to prove its effectiveness as a possible agent for the treatment of cancer.

Styles APA, Harvard, Vancouver, ISO, etc.

6

Williamson, Rhett J. « Qualitative Analysis for the Characterization and Discrimination of Printing Inks ». FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/3055.

Texte intégral

Résumé :

Improvements in printing technology and the wide accessibility of advanced printers has resulted in an increase in counterfeiting. Of particular interest to forensic document examiners, ink analysis of security documents has emerged as an important tool for the analysis, comparison, and association of inks to a potential production source. In this study, methods were developed for Py-GC/MS, ATR-FTIR, DART-MS, and MALDI-MS analyses of printing inks of four classes: 78 inkjet inks, 76 toners, 79 offset inks, and 86 intaglio inks in order to generate information on the organic chemical characterization of the inks to determine the ability to associate and discriminate the inks for uses in security document examinations. The suite of analytical techniques evaluated in the study focused on having the following analytical characteristics: 1) rapid analysis time, 2) little-to-no sample preparation, 3) minimal destructiveness to the sample, 4) allow for association of inks with the same source of origin as well as discrimination of inks originating from different sources. As a result of this study, a novel searchable library database of inks was developed for use with each analytical chemical method that allows for data fusion. Py-GC/MS analysis was used to achieve >63% discrimination of toner inks on the basis of the characterization of polymer degradation products. The combination of a protocol implementing first ATR-FTIR and subsequently DART-MS analysis resulted in >96% discrimination for toners, 95% for inkjet, >92% for offset, and >54% for intaglio. In addition, a case study was performed using DART-MS to illustrate its utility as a tool for ink analysis in document examination. The results of MALDI-MS analyses from two different instruments resulted in >90% discrimination of a subset of all inks by characterizing the colorant molecules present in ink formulations. A study characterizing luminescent compounds present in the formulation of inks in crossed-line intersections was performed using a combination of MALDI-MS, LC-MS, and TLC. Overall, it was shown that the combination of analytical techniques included within this dissertation can provide information on the organic chemical composition of four classes of printing inks, which is useful for the future of document examination.

Styles APA, Harvard, Vancouver, ISO, etc.

7

Theophilo, Paulo Henrique Medeiros. « Qualitative Analytical Chemistry in Federal University of CearÃ : a look on the Theaching using Lerarning Objects ». Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=13427.

Texte intégral

Résumé :

HÃ cerca de vinte anos, o pesquisador Paschoal Senise do Instituto de QuÃmica da Universidade de SÃo Paulo, ressaltava a necessidade de se refletir sobre a diferenÃa entre QuÃmica AnalÃtica e AnÃlise QuÃmica. Ele acreditava que a conscientizaÃÃo desta diferenÃa proporcionaria um maior aproveitamento da disciplina de QuÃmica AnalÃtica Qualitativa. No Brasil, esta foi introduzida nas universidades a partir de 1935, com base nos ensinamentos da chamada Escola de Rheinboldt. Em meio a esta ascensÃo, os trabalhos publicados sobre QuÃmica AnalÃtica Qualitativa, a partir dos anos sessentas, tÃm seu cunho direcionado para as atividades de ensino. Os currÃculos dos cursos universitÃrios norte-americanos reduziram a carga horÃria, outras relegando seu ensino para as atividades de laboratÃrio na disciplina de QuÃmica Geral, ou mesmo, retirando a disciplina por completo dos cursos. Tal situaÃÃo repercutiu no mundo cientÃfico e vÃrios educadores e pesquisadores, dentre eles Henry Taube, PrÃmio Nobel de QuÃmica de 1983, se manifestaram a favor da manutenÃÃo da disciplina como forma de introduzir a quÃmica descritiva e motivar os alunos a estudarem as reaÃÃes quÃmicas. A presente pesquisa evidencia a importÃncia e a situaÃÃo na qual se encontra a QuÃmica AnalÃtica Qualitativa na Universidade Federal do CearÃ. Nessa pesquisa 5 turmas foram observadas das quais duas delas foram utilizadas como turma de trabalho onde entrevistou-se 37 estudantes com objetivo de verificar a satisfaÃÃo e os problemas relacionados Ã disciplina em questÃo. Fez-se uma historicizaÃÃo da disciplina e traÃou-se uma anÃlise crÃtica em relaÃÃo Ã aplicaÃÃo da mesma nos cursos oferecidos pela Universidade Federal do CearÃ. De acordo com os resultados na fase de observaÃÃo e entrevista, fez-se uma reestruturaÃÃo do material didÃtico com o objetivo de colaborar com o professor na contextualizaÃÃo necessÃria Ã abordagem da tecnologia de informaÃÃo e comunicaÃÃo (CTS). Promoveu-se a confecÃÃo de objetos de aprendizagem como vÃdeos com as tÃcnicas de anÃlises, diapositivos, espectroscÃpio didÃtico e banners que facilitam a apresentaÃÃo do conteÃdo e o contextualizam. A reestruturaÃÃo proporciona maior efetividade na apresentaÃÃo, reduzindo o tempo de exposiÃÃo e melhorando o aprendizado. De acordo com as opiniÃes de discentes e docentes foi possÃvel verificar maior desenvoltura das turmas logo nas primeiras aulas. O material elaborado nÃo tem a pretensÃo de substituir o trabalho do professor ou mesmo substituir livros didÃticos, mas sim de conseguir facilitar a compreensÃo do estudante, fazendo com que o conteÃdo seja melhor apropriado pelo discente da disciplina QuÃmica AnalÃtica Qualitativa, oferecida nos cursos de Licenciatura em QuÃmica, nas categorias presenciais e semipresenciais, da Universidade Federal do CearÃ.
Some twenty years, Pascoal Senise researcher at the Institute of Chemistry, University of SÃo Paulo, emphasized the need to reflect on the difference between Analytical Chemistry and Chemical Analysis. He believed that awareness of this difference would provide a better use of the discipline of Qualitative Analytical Chemistry. In Brazil, this was introduced in universities after 1935, based on the teachings of the so-called School of Rheinboldt. Amidst the rise, papers on Qualitative Analytical Chemistry, from the years sixties have its seal directed to teaching activities. The curricula of American university courses reduced workload, other relegating teaching to the lab activities in the discipline of General Chemistry, or even completely removing the discipline courses. This situation affected the scientific world and several educators and researchers, among them Henry Taube, Nobel Prize in Chemistry 1983, were in favor of maintaining discipline as a way of introducing the descriptive chemistry and motivate students to study chemical reactions. This research highlights the importance and the situation in which one finds the Qualitative Analytical Chemistry at the Federal University of CearÃ. There was a historicizing of Discipline and drew up a critical analysis regarding the application of the same courses offered by the Federal University of CearÃ. According to the results of this analysis, it is believed that a restructuring of its courseware in order to collaborate with the teacher in the context of necessary information and communication (CTS) technology approach is needed. Promoted to making videos with technical analysis, slides that facilitate the presentation of content and contextualize. The restructuring provides greater effectiveness in the presentation, reducing the exposure time and improve learning. Thus, the extra time due to the improvement in the approach can be used in discussions that promote the emergence of investigative thinking for the student to develop their creative intuition and ability necessary to Chemistry rofessional. It was possible to detect greater ease of classes in the first few lessons. The section does not pretend to replace the teacher's job or even replace textbooks, but to achieve facilitate student understanding, making the content of the course is best suitable for student discipline Qualitative Analytical Chemistry, offered in undergraduate courses in Chemistry, in the classroom and hybrid categories, the Federal University of CearÃ.

Styles APA, Harvard, Vancouver, ISO, etc.

8

Haraguchi, Toshio. « Análise químico-farmacêutica da buspirona ». Universidade de São Paulo, 1990. http://www.teses.usp.br/teses/disponiveis/9/9139/tde-12022015-171521/.

Texte intégral

Résumé :

A buspirona, ansiolítico da segunda geração usada no tratamento de ansiedade, foi analisada fisico-quimica e quimicamente, com o objetivo de fornecer subsídios para a respectiva monografia. Fizeram-se os seguintes testes de caracterização deste fármaco: faixa de fusão, análise elementar, pH, umidade e solubilidade. Realizaram-se igualmente as provas de identificação constante de: análise cromatográfica, ensaio de cloreto, espectro no infravermelho, espectro no ultravioleta, espectro de ressonância magnética protônica, espectro de massa, espectro de carbono-13, termogravimetria, calorimetria exploratória diferencial e cromatografia líquida de alta resolução. Efetuaram-se, também, determinações quantitativas pelos seguintes métodos: micro-Kjeldahl, gravimétrico, potenciométrico com nitrato de prata, doseamento com ácido perclórico em meio acetico por volumetria e potenciometria e espectrofotométrico no ultravioleta. Concluiu-se que: 1) o teste de caracterização mais indicado e o ponto de fusão; 2) das provas de identificação, as mais simples e rápidas são as seguintes: identificação de cloreto, infravermelho e ultravioleta; 3) dos métodos de determinação quantitativa, mais prático e o doseamento com ácido perclórico em meio acético, usando como indicador o vermelho de quinaldina.
Buspirone, a new non-benzodiazepine anxiolytic agent which is effective in the treatment of anxiety, was analyzed by physicochemical and chemical methods, having in mind a monograph of this drug. The fo1lowing characterization tests of this drug were performed: melting range, elementary analysis, pH, loss in drying, solubility. The following identification tests were also carried out: chromatographic analysis, identification of chloride, infrared absorption, ultraviolet absorption, protonic magnetic resonance spectra, mass spectrum, carbon 13C NMR spectroscopy, thermogravimetry and high performance liquid chromatography. Quantitative determinations were obtained through the following methods: micro-Kjeldahl, gravimetry, potenciometry, non-aqueous titration with perchloric acid and ultraviolet spectrometry. The following conclusions were reached: 1) the best characterization test is the melting range; 2) the simplest and quickest tests of identification are: identification of chloride, infrared and ultraviolet spectrophotometry; 3) the most practical method is the non-aqueous assay with perchloric acid.

Styles APA, Harvard, Vancouver, ISO, etc.

9

Smith, Kerri M. « Quantitative and qualitative mass spectrometric analysis of anticancer agents, drugs of abuse and enzyme-inhibitor complexes ». Cleveland State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=csu1373987824.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

10

Calefi, Roberta Maura. « Ensino de química analítica qualitativa na graduação : sua importância e metodologias adotadas ». Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/75/75132/tde-26072010-101443/.

Texte intégral

Résumé :

Um estudo sobre alguns aspectos relacionados ao ensino de Química Analítica Qualitativa no Brasil é apresentado, com o objetivo de oferecer subsídios para discussão sobre a importância e as formas de se trabalhar o conteúdo dessa disciplina em nosso país. Inicialmente, foi feito um levantamento dos aspectos históricos da análise qualitativa, sua introdução e desenvolvimento no ensino superior brasileiro, com destaque ao seu introdutor, o Prof. Heinrich Rheinboldt, a autores nacionais que se ocuparam do assunto, como o Prof. Paschoal Senise (e seus seguidores) e às pesquisas desenvolvidas em nosso país, por Fritz Feigl. Também foi enviado um questionário com 11 perguntas sobre diversos aspectos da disciplina, dirigidas a 134 docentes responsáveis por ministrar Química Analítica Qualitativa em 75 Instituições de Ensino Superior, tanto públicas como particulares, abrangendo todo o território nacional. As questões tinham o objetivo de avaliar a importância dada à disciplina, seu conteúdo e formas de apresentação pelo país. Destes, apenas 20 responderam e suas respostas foram compiladas e analisadas sob diversos aspectos. Como última parte do trabalho foi feita uma resenha das principais metodologias de ensino experimental da Química Analítica Qualitativa, tendo como base os principais livros-texto, citados pelos professores no questionário. Também foram incluídas algumas propostas de metodologia nas quais se evita o uso do controverso sulfeto de hidrogênio. A principal conclusão é que há uma divergência profunda de opiniões sobre a apresentação da disciplina quanto à sua forma e carga horária, porém com certa convergência quanto ao conteúdo. Entretanto, a maioria dos professores que responderam ao questionário, concordou com a importância da disciplina na formação do estudante de química.
A study of some aspects considered relevant, concerning the teaching of Qualitative Chemical Analysis in Brazil is presented, looking for subsidy discussions on the importance and approaches of teaching this discipline. Initially historical aspects of the Qualitative Analysis as well as its introduction in our country is presented emphasizing its introducer Prof. Heinrich Rheinboldt and Brazilian authors that concerned on the subject as Prof. Paschoal Senise (and his students) and the research developed here by Fritz Feigl in the last century. A questionary with 11 questions about several aspects of the discipline was sent out to 134 teachers responsible by teaching Qualitative Chemical Analysis in 75 universities and colleges (state and private) all around the country. The questions had the goal of evaluating the importance attributed to the contents and didactical approach used in the discipline. Only 20 answers were received back and their contents were compiled and analyzed under several aspects. As the last part of the work a summary of the main experimental teaching approaches of Qualitative Chemical Analysis based on the text-books mostly cited in the answers to the questionary is presented together with some propositions from the literature that avoid the use of the controversial hydrogen sulphide. The main conclusion is that there is a deep divergence about how to present the contents of the discipline concerning the teaching approach and the time dedicated to the subject with certain agreement in relation to the contents. However, the majority of the teachers that attempt the questionary agreed with the importance of Qualitative Chemical Analysis in the formation of the chemistry student.

Styles APA, Harvard, Vancouver, ISO, etc.

11

Eckart, Teresa McClain. « Productive Whole-Class Discussions : A Qualitative Analysis of Peer Leader Behaviors in General Chemistry ». [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0003222.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

12

Pruyn, Marley. « Qualitative Detection of Selected Designer Drugs and Relevant Metabolites in Environmental Water Samples ». FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2571.

Texte intégral

Résumé :

Designer drugs are compounds which have been synthetically derived from illicit drugs. After consumption, drugs and their metabolites are introduced into the sewage water which is treated and disposed into the environment. A combined target, suspect and non-target workflow was created to detect designer drugs in environmental water samples. Multiple water samples were spiked with an unknown mixture of drugs and metabolites to assess the efficiency of the method. Samples were collected from sewage influent and effluent pipes, downstream from a sewage outfall and reclaimed water. Analysis was conducted with high resolution MS using the QExactive Orbitrap. Screening was performed using a database compiled in-house using TraceFinder EFS. Structure confirmation was achieved using MassFrontier. Target drugs and their metabolites were detected in sewage influent but not in sewage effluent, downstream of the effluent pipe, or in reclaimed water. The workflow was adequate to detect designer drugs in multiple water matrices at concentrations as low as 20ppt.

Styles APA, Harvard, Vancouver, ISO, etc.

13

Berndtson, Emma. « Qualitative analysis of LGD-4033 and its metabolites in equine plasma using UHPLC-MS(MS) for doping control purposes ». Thesis, Uppsala universitet, Analytisk kemi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-327256.

Texte intégral

Résumé :

A new class of drugs has been developed for treatment of muscle and bone mass wasting diseases called non-steroidal selective androgen receptor modulators (SARMs). Because of their positive androgenic effects such as muscle gain, they are desirable as performance enhancers. One of those substances is LGD-4033 (4-[(2R)-2-[(1R)-2,2,2-trifluoro-1-hydroxyethyl]pyrrolidin-1-yl]-2-(trifluoromethyl)- benzonitrile). It has been detected in human samples in routine doping control and another SARM has been detected in an equine blood sample in routine doping control. It is therefore indicated that SARMs need to be screened for in routine testing in equestrian sport. The aim of this project was to identify what metabolites were found in equine plasma after an intra venous administration of LGD-4033 using UHPLC coupled with QToF-MS and determine whether the parent compound or any of its metabolites were most suitable for doping control. With the sample preparation method protein precipitation, six possible metabolites were identified in samples from three horses. Two of the metabolites were identified as phase I-metabolites (monohydroxylated and dihydroxylated). Four of the metabolites were identified as phase II-metabolites, where glucuronidation had occurred. The most suitable species for doping control were determined based on a semi- quantification and were M1a, M2 and M3a.

Styles APA, Harvard, Vancouver, ISO, etc.

14

Sanchez, João Ricardo. « A atividade orientadora de ensino como alternativa metodológica para a abordagem de metais pesados na disciplina de Química Analítica Qualitativa ». Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/59/59138/tde-19092014-111235/.

Texte intégral

Résumé :

A disciplina Química Analítica Qualitativa (QAQ), no contexto do Departamento de Química (DQ) da Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP), passou ao longo dos anos por uma redução de sua carga horária, que era de 11 horas semanais (1990) para 6 horas semanais (2001). Com a limitação na carga horária de QAQ, alguns grupos analíticos (grupos IV e V Metais Pesados), foram aos poucos, deixando de ser abordados no curso de Licenciatura e Bacharelado em Química, ofertados pelo DQ. Devido à importância destes metais na atualidade, acreditamos que não poderiam ser suprimidos do currículo do nosso curso. Desta forma, elaborou-se uma AOE sobre os grupos analíticos IV e V, que haviam sido retirados da marcha analítica e nesta dissertação o objetivo foi investigar a potencialidade da Atividade Orientadora de Ensino (AOE) como estratégia de ensino-aprendizagem em QAQ. A fundamentação teórica deste trabalho pautou-se nos estudos de Vygotsky sobre atividade e consciência e também na Teoria da Atividade proposta por Leontiev. Participaram da AOE 23 alunos da Licenciatura em Química, regularmente matriculados na disciplina de QAQ, que é oferecida no terceiro semestre do curso. A AOE foi desenvolvida no 1o Semestre de 2013 e incluiu três encontros previamente acordados e inseridos no cronograma da disciplina. Os dois primeiros encontros foram desenvolvidos em duas aulas simples de 1h40, para a discussão teórica acerca do tema central - metais pesados - e consequente método de identificação e separação dos mesmos. Nestes, os alunos desenvolveram uma proposta de rota de separação, pautados em uma notícia acerca da utilização de metais em batons e brilhos labiais. O terceiro encontro foi desenvolvido no laboratório didático experimental, em uma aula dupla de 3h30, na qual os alunos colocaram em prática a rota proposta, ao manipularem uma amostra fictícia dos cosméticos. Os encontros foram vídeos gravados, transcritos e posteriormente analisados a partir do método dialético. A metodologia de pesquisa adotada foi a pesquisa participante. A AOE como metodologia de ensino propiciou a interação entre os alunos da disciplina e o professor/pesquisador. Mobilizou os alunos a buscarem informações que pudessem solucionar os problemas relativos aos metais pesados, bem como articular as mesmas estabelecendo nexos entre elas e assim, conceber os conceitos envolvidos. No momento de discussão, pôde-se notar o favorecimento de nexos relacionados à: toxicidade dos metais e seus efeitos no corpo humano; bioacumulação e biomagnificação, saúde do homem, efeito das ações do homem no meio ambiente, impacto do conhecimento científico na sociedade e ambiente, proposta de identificação e separação, entre outros. Os momentos de fala externa para o grupo favoreceram que os alunos organizassem seu pensamento e sua compreensão dos conceitos. Esta AOE foi inserida na matriz curricular na disciplina e contribuiu para a avaliação dos alunos, que receberam uma nota na forma de Prática como Componente Curricular, item exigido no projeto político pedagógico do curso de Licenciatura em Química.
The Qualitative Analytical Chemistry discipline (QAC), in the context of the Chemistry Department (CD) of the Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto-FFCLRP (School of Philosophy, Sciences and Letters of Ribeirão Preto), passed over the years by a reduction of its workload, which used to be 11 hours per week (1990) to 6 hours per week (2001). By limiting the workload of QAC, some analytical groups (groups IV and V - Heavy Metals), were gradually ceasing to be covered in the Chemistry Graduation Course, offered by CD. Due to the importance of these metals at present, we believe that they could not be removed from the curriculum of our course. Thus, a Teaching Guiding Activity (TGA) about the analytical groups IV and V, which had been removed from the analytical procedures, has been elaborated and the objective in this dissertation was to investigate the potential of TGA as a teaching-learning strategy in QAC. The theoretical referential of this work was based on the studies of Vygotsky about activity and consciousness and also on the Activity Theory proposed by Leontiev. It was attended by 23 students of the Chemistry Graduation Course, regularly enrolled in the discipline of QAC, which is offered in the third semester of the course. The TGA was developed in the first semester of 2013, and included three meetings previously agreed into the schedule of the discipline. The two initial meetings were developed in two simple classes of 1h40 to the theoretical discussion concerning the central subject - heavy metals - and consequent separation and identification method of the aforementioned metals. In these meetings, the students developed a proposal for separation, guided by a piece of news about the use of metals in lipsticks and lip gloss. The third meeting was developed in the experimental teaching laboratory, in a double lesson of 3h30, in which the students put into practice the proposed route, by manipulating a fictitious sample of cosmetics. The meetings were recorded, transcribed and later analyzed from the dialectical method. The research methodology used was the participatory research. The TGA as teaching methodology provided the interaction between students of the discipline and the teacher/researcher. It also mobilized the students to search for information that would solve the problems related to heavy metals, as well as articulating such information, fomenting links among them and thus, conceive the concepts involved. At the moment of the discussion, it could be noticed the favoring of links related to: toxicity of metals and its effects in the human body; bioaccumulation and biomagnification, men\'s health, effect of human actions on the environment, impact of scientific knowledge in society and environment, the proposed identification and separation, among others. The moments of external speaking for the group, favored the students to organize their thinking and their understanding of concepts. This TGA was inserted into curriculum in the discipline and contributed to the assessment of students who received a grade in the form of Prática como Componente Curricular (\"Practical Course as Curricular Component\") item required in the political pedagogical project of the Chemistry Graduation Course.

Styles APA, Harvard, Vancouver, ISO, etc.

15

Tan, Kim C. D. « Development and application of a diagnostic instrument to evaluate secondary students' conceptions of qualitative analysis ». Thesis, Curtin University, 2000. http://hdl.handle.net/20.500.11937/1361.

Texte intégral

Résumé :

The primary purpose of this study was to develop a two-tier multiple choice diagnostic instrument to assess Singapore Grade 10 students' (15 to 17 years old) understanding and alternative conceptions of qualitative analysis. Additional and related purposes were to determine whether more advanced chemistry students, for example, junior college (Grade 11 and 12) students, undergraduates and graduate trainee-teachers have a better understanding of basic qualitative analysis than secondary students, and to develop appropriate teaching strategies and materials on qualitative analysis based on the findings of this study and a review of the literature on practical work.The results from the administration of the diagnostic instrument showed that Singapore Grade 10 students had many alternative conceptions related to qualitative analysis, and these were grouped under the headings of 'Displacement', 'Redox', 'Dissolution', 'Addition of acid' and 'Heating'. The cross-age study showed that the more advanced chemistry students generally had a better understanding of basic qualitative analysis but had similar alternative conceptions as the Grade 10 students. However, the alternative conceptions identified were consistently held by only a small number of students across all contexts examined in the diagnostic instrument, suggesting that a number of students either had more than one conception for a particular concept or no conceptions at all. The results from the trial of the qualitative analysis teaching package indicated that the teaching package was feasible. Teachers involved in the trial found it structured and comprehensive, and the students who experienced the teaching package performed better on the diagnostic instrument than a comparison group.The study recommends that better ways of conducting qualitative analysis practical work are required, and using the teaching package may be a step in this direction. The study also raises questions about the value of teaching qualitative analysis in secondary schools when important reactions involved in qualitative analysis are omitted from the syllabus, and when there is little incentive and time in the school curriculum for learners to understand what they are doing in qualitative analysis.

Styles APA, Harvard, Vancouver, ISO, etc.

16

Gaubeur, Ivanise. « Desenvolvimento de métodos espectrofotométricos em condições estacionária e em fluxo para determinação de zinco em amostras biológicas e farmacêuticas ». Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-23012019-093715/.

Texte intégral

Résumé :

Métodos espectrofotométricos em condições estacionária e em fluxo para determinação de Zn(II) foram desenvolvidos com base na formação do complexo de Zn(II) com di-2-piridil cetona saliciloilhidrazona (DPKSH), em meio de etanol-água 50% (V/V) e pH 4,5. Os complexos de Zn(II) com DPKSH foram caracterizados utilizando diferentes técnicas e as respectivas constantes de formação (βl 1,07x105 e β2 1,05x1010) e absortividades molares, em 376 nm, (εl 1,1x104 e ε2 4,5x104) determinadas. Os parâmetros para o método em condição estacionária foram otimizados e, a seguir, construiu-se a respectiva curva analítica. Obteve-se uma faixa de linearidade (lei de Beer) de (0,0293 a 2,01)x10-5mol. L-1, absortividade molar média (em 376 nm, em meio de etanol-água 50% (V/V) e pH 4,5) de 4,83x104 mol-1.L.cm-1 e limite de detecção igual a 1,24x10-7 mol.L-1 (8,11 µg.L-1). Avaliou-se a interferência de 43 íons. Alguns destes que apresentaram interferência positiva são comuns em preparações farmacêuticas e amostras biológicas, porém tal interferência pode ser facilmente eliminada. Aplicou-se o método desenvolvido à preparações farmacêuticas e amostras biológicas. Comparando-se os resultados com a técnica de absorção atômica com chama, obteve-se grande concordância. O método espectrofotométrico em fluxo foi desenvolvido a partir de alguns parâmetros previamente estudados e estabelecidos. Construiu-se a curva analítica e obteve-se uma faixa de linearidade de (0,332 a 7,04)x 10-5 mol.L-1 e limite de detecção 7,46x10-7 mol.L-1 (48,8 µg.L-1). Aplicou-se o método em preparações farmacêuticas e comparando-se os resultados com a técnica de absorção atômica com chama observou-se grande concordância. Com a finalidade de aplicar o método em fluxo a amostras biológicas, foi acoplada ao sistema uma coluna com resina de troca iônica no lugar da alça de amostragem. Após avaliar alguns parâmetros, construiu-se a curva analítica que apresentou uma faixa de linearidade de (0,126 a 3,15)x10-5 mol.L-1 e limite de detecção 2,12x10-7 mol.L-1 (13,9 µg.L-1).
Spectrophotometric methods in stationary and flow conditions were developed for Zn(II) determination based on the complex formation of Zn(II) with di-2-pyridyl ketone salicyloylhydrazona (DPKSH), in ethanol-water 50% (V/V) medium and pH 4.5. The complexes Zn(II)/DPKSH were characterized by several methods and the respective formation constants (β1 1.07x105 and β2 1.05x1010) and molar absorptivities, in 376 nm, (ε1 1.1x104 and ε2 4.5x104) were determinated. Parameters for the stationary method were optimized and, the analytical curve was obtained. A linear behavior (Beer\'s law) was verified in the range (0.0293 and 2.01)x10-5mol.L-1, the medium molar absorptivity (in 376 nm, ethanol-water 50% (V/V) medium and pH 4.5) and the detection limit are 4.83x104 mol-1.L.cm-1 and 1.24x10-7 mol.L-1 (8.11 ppb), respectively. The interference of 43 ions was evaluated. Some of them that showed present a positive interference are commom in pharmaceutical formulations and biological samples, but such interference could be easily eliminated. The developed method was applied to pharmaceutical formulations and biological samples. The results complied well with atomic absorption (flame atomization) technique. A spectrophotometric method in flow was developed upon some previously established parameters. The analytical curve was determined and a linear range was verified between (0.332 to 7.04)x10-5 mol.L-1, and the detection limit 7.46x10-7 mol.L-1 ( 48.8 µg.L-1). This method was applied to pharmaceutical formulations and the results showed a good agreement with atomic absorption (flame atomization) technique. Aiming at employing the flow method to biological samples an ion-exchange resin column was adapted substituting the sampling handle. After evaluating some parameters the analytical curve was determined and it displayed a linear range of (0.126 to 3.15)x10-5 mol.L-1, and detection limit 2.12x10-7 mol.L-1 (13.9 µg.L-1).

Styles APA, Harvard, Vancouver, ISO, etc.

17

Lohnes, Mitchell T. « Multivariate approaches to qualitative and quantitative analysis in chemistry, I. Calibration with correlated errors ; II. Window target-testing factor analysis ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ36495.pdf.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

18

Anderson, Jennifer Christine. « QUANTITATIVE AND QUALITATIVE INVESTIGATIONS INTO URINARY CALCULI USING INFRARED MICROSPECTROSCOPY ». Miami University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=miami1173303815.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

19

Capri, Maria da Rosa. « Dissolução química parcial \"on line\" de aço inoxidável seguida de determinação de Cr, Mn e Ni por espectrometria de emissão ótica com plasma indutivamente acoplado (ICP-OES) ». Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-25102018-140251/.

Texte intégral

Résumé :

O objetivo deste trabalho foi o desenvolvimento de metodologia analítica versátil e rápida para a determinação de Cr, Mn e Ni em aços martensíticos e austeníticos, através do processo de dissolução química parcial em sistema de injeção em fluxo acoplado ao Espectrômetro de Emissão Ótica acoplado indutivamente (ICP-OES). O procedimento, também priorizou menor manipulação de amostra e consumo de reagentes. A solução extratora, HNO3 e HCI 7,0 mol L-1 e 6,0 mol L-1 respectivamente 1:1 v/v foi utilizada para a dissolução química parcial dos aços inoxidáveis. A quantificação dos metais dissolvidos foi feita utilizando-se o método da somatória, que relaciona a concentração de um elemento individual com a somatória dos elementos determinados, segundo a fórmula: i% = Ci /Ct x 100, onde Ci é a concentração do elemento i e Ct é a soma das concentrações de todos elementos determinados. Os resultados não apresentaram diferença significativa em um nível de confiança de 95% com os valores certificados das amostras de referência e com os valores da dissolução total assistida por microondas. O procedimento apresentou freqüência analítica de 20 determinações por hora.
The objective of this work was the development of a versatile and fast analytical methodology for the determination of Cr, Mn, and Ni in martensitic and austenitic steels, through on-line partial chemical dissolution using a flow injection system coupled to an ICP-OES. The procedure also aimed the smallest sample manipulation and reagents consumption. The extractor solution, 7.0 mol L-1 HNO3 and 6.0 mol L-1 HCI 1:1 v/v, was used to the on-line partial chemical dissolution of the stainless steels. The quantification of the dissolved metals was made using a method, that relate the concentration of an individual element with the sum of all elements concentrations, applying the formula: i% = Ci /Ct x 100, where Ci is the concentration of the element i and Ct is the sum of the concentration of all elements determined. No significant difference has been present by the results, at a confidence level of 95%, with the certified values of the reference materials and with the total dissolution values obtained by microwave - assisted sample pretreatment. The procedure presented analytic frequency of 20 determinations per hour.

Styles APA, Harvard, Vancouver, ISO, etc.

20

Lynch, Robert Bruce Rodes. « The Quantitative and Qualitative Analysis of Cohorts' Early Enrollment in Physics| concurrent with enrollment in mathematics, biology and chemistry ». Thesis, University of California, Davis, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3646337.

Texte intégral

Résumé :

Cohorts of 48 entering biological science majors was recruited in the fall of 2007 and again in 2008 and 2009 for the Interdisciplinary Science Experience (ISE). These ISE students enrolled in their own sections of standard courses of physics, chemistry, and biology. In these courses average ISE student out-performed their non-cohort peers by up to a full letter grade. A qualitative analysis of ISE student interviews illuminates the student experience and shows how the ISE students perceived themselves to be different than their non-cohort peers. Quantitative modeling of student performance shows that higher grades are correlated with multiple factors. These factors includes admissions characteristics such as high school GPA, and SAT scores, as well as demographic information. These trends support and elaborate on the selection narratives told by participants. Additionally the quantitative model found that higher student performance is predicted by structural aspects of the ISE program, specifically the timing of course, enrolling as a freshmen in many of their courses, and the sequencing of physics and chemistry courses. There is a statistically significant benefit to student performance in general and organic chemistry courses associated with completing the first quarter of the Physics for Bio-Science majors prior to enrollment. Further the combination of quantitative and qualitative data suggest that there is a epistemological transfer of problem solving skills and outlook from the physics to the chemistry courses.

Styles APA, Harvard, Vancouver, ISO, etc.

21

Laidler, Paul. « Qualitative and quantitative analysis of human chorionic gonadotropin : applied to drug control in sport ». Thesis, King's College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309125.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

22

Tan, Kim C. D. « Development and application of a diagnostic instrument to evaluate secondary students' conceptions of qualitative analysis ». Curtin University of Technology, Science and Mathematics Education Centre, 2000. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=11512.

Texte intégral

Résumé :

The primary purpose of this study was to develop a two-tier multiple choice diagnostic instrument to assess Singapore Grade 10 students' (15 to 17 years old) understanding and alternative conceptions of qualitative analysis. Additional and related purposes were to determine whether more advanced chemistry students, for example, junior college (Grade 11 and 12) students, undergraduates and graduate trainee-teachers have a better understanding of basic qualitative analysis than secondary students, and to develop appropriate teaching strategies and materials on qualitative analysis based on the findings of this study and a review of the literature on practical work.The results from the administration of the diagnostic instrument showed that Singapore Grade 10 students had many alternative conceptions related to qualitative analysis, and these were grouped under the headings of 'Displacement', 'Redox', 'Dissolution', 'Addition of acid' and 'Heating'. The cross-age study showed that the more advanced chemistry students generally had a better understanding of basic qualitative analysis but had similar alternative conceptions as the Grade 10 students. However, the alternative conceptions identified were consistently held by only a small number of students across all contexts examined in the diagnostic instrument, suggesting that a number of students either had more than one conception for a particular concept or no conceptions at all. The results from the trial of the qualitative analysis teaching package indicated that the teaching package was feasible. Teachers involved in the trial found it structured and comprehensive, and the students who experienced the teaching package performed better on the diagnostic instrument than a comparison group.The study recommends that better ways of conducting qualitative analysis practical work are required, and using the teaching ++
package may be a step in this direction. The study also raises questions about the value of teaching qualitative analysis in secondary schools when important reactions involved in qualitative analysis are omitted from the syllabus, and when there is little incentive and time in the school curriculum for learners to understand what they are doing in qualitative analysis.

Styles APA, Harvard, Vancouver, ISO, etc.

23

Kucheriavaia, Daria. « Applications of Mass Spectrometry for Qualitative Analysis and Imaging of Microcystins in Mouse Tissues, Cyanobacterial Cells and Water ». University of Toledo / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1596824964059216.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

24

Araújo, Renata Bernardo. « Instrumentos de avaliação na atividade experimental da disciplina de Química Analítica Qualitativa ». Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/59/59138/tde-16102014-192505/.

Texte intégral

Résumé :

A avaliação somativa é a que prevalece nas instituições de ensino superior, os instrumentos de avaliação tradicionalmente utilizados (provas e relatórios) fornecem informações sobre a aprendizagem de conteúdos conceituais e ficam à margem a avaliação dos conteúdos procedimentais e atitudinais. Além disso, provas e relatórios são realizados num momento final das atividades, tardio para um feedback adequado, não havendo tempo para intervir na aprendizagem. Emerge nesse contexto a necessidade de se estudar e refletir sobre os processos avaliativos utilizados na disciplina de Química Analítica Qualitativa (QAQ). Diante disto, tinha-se uma pergunta: haveriam instrumentos adequados e ao mesmo tempo abrangentes que permitissem melhorar o processo avaliativo na disciplina QAQ? Com o objetivo de responder a esta questão foram aplicadas e analisadas duas modalidades de instrumentos de avaliação: pré-exercícios de laboratório (PEL) e grades de observação (GO). Esta pesquisa é de natureza qualitativa, e foi fundamentada em contribuições teóricas de autores que são a favor da avaliação no decorrer do processo de ensino. Sendo assim, teve-se como uma das principais referências Fernandes (2006), que propõe a expressão Avaliação Formativa Alternativa (AFA), alternativa a tradições avaliativas em que o resultado é obtido após o processo de ensino e aprendizagem. Na AFA o professor vai obtendo informações sobre a aprendizagem dos alunos, permitindo assim, o feedback das atividades propostas, interações aluno-professor, e as notas são consideradas pois estas servem como registro. A pesquisa foi desenvolvida no decorrer da disciplina QAQ, com a turma do terceiro semestre do curso de Licenciatura em Química noturno na Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo (FFCLRP/USP). Concluiu-se que os instrumentos de avaliação PEL e GO foram eficientes no acompanhamento da aprendizagem dos alunos no decorrer da disciplina. Estes instrumentos proporcionaram a AFA, e complementam a avaliação realizada tradicionalmente na disciplina QAQ, dessa forma reforçam o acompanhamento dos alunos contribuindo para a melhoria na aprendizagem e no processo de avaliação da disciplina.
The summative assessment is prevailing in higher education institutions, the traditional evaluation tools used (tests and reports) provide information on conceptual learning does not include assessments of experimental procedures and attitudinal content. Besides, examinations and reports are performed in a final stage of activities without proper feedback, there is no time to help in the learning. Emerges in this context the need to study and reflect on the assessment processes used in the discipline of Qualitative Analytical Chemistry (QAC). This rises to the following question: are there more specific and more comprehensive instruments, which allow an improvement of the evaluation process in the Qualitative Analytical Chemistry (QAC)? In order to answer this question, we applied and analyzed two types of assessment tools: pre-lab work (PLW) and observation grids (GO). This research qualitative in nature was based on theoretical contributions of the authors that are in favor of the assessment during the teaching process. Fernandes (2006) was as one of the main references, he proposed the term Alternative Formative Assessment (AFA), the alternative assessment traditions in which the result is obtained after the process of teaching and learning. While using AFA, the teacher obtains information about students\' learning, allowing the feedback of the proposed activities, student-teacher interactions and considering the marks, as they serve as a record. The research was developed during the discipline of QAC, with the class of the third semester of the degree chemistry at night in the Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo (FFCLRP/USP). It was concluded that the assessment instruments PLW and GO were effective in accompaniment students\' learning during the discipline. These instruments provided the AFA, for the evaluation supplement traditionally held in the discipline QAC, and thus reinforce the monitoring of students contributing to the improvement in learning and evaluation process of the discipline.

Styles APA, Harvard, Vancouver, ISO, etc.

25

Moreno, Ruben Gregorio Moreno. « Determinação de mercúrio em amostras ambientais por espectrometria de absorção atômica com atomização eletrotérmica em forno de grafite com superfície modificada ». Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-15022019-113640/.

Texte intégral

Résumé :

Um procedimento eletroquímico para deposição de paládio no interior de um tubo de grafite para modificação química permanente e um sistema de geração de vapor frio para a determinação de níveis traços de mercúrio em água e sedimento através de espectrometria de absorção atômica é proposto. A célula eletroquímica tubular para as deposições de paládio em fluxo foi construída aproveitando a estrutura original do tubo de grafite o qual opera como eletrodo de trabalho. Um tubo de aço inoxidável, posicionado na saída da célula, é usado como o eletrodo auxiliar. O valor do potencial aplicado no eletrodo de grafite é medido contra um micro eletrodo de referência de Ag/AgCl inserido sobre o eletrodo auxiliar. Soluções de paládio em tampão de acetato (100 milimol L-1, pH=4,70), numa vazão de 0,5 mL min-1 foram usados para executar a deposição eletroquímica durante o intervalo de tempo de 60 min. O sistema de geração de vapor frio consiste de um micro-reator de polietileno e frasco separador líquido-gás, volume total de 4,0 ml, que é descartado depois de cada amostragem para evitar inter-contaminação das amostras. Volumes de 1,0 ml de reagente (2,0% m/v NaBH4 em 0,10 mol L-1 de NaOH) e 1,0 ml de soluções analíticas ou amostras em 0,25 mol L-1 de HNO3 são levados para o reator e separador líquido-gás usando uma bomba peristáltica. O vapor de mercúrio é transportado ao tubo de grafite modificado eletroquimicamente com fluxo de argônio de 212 ml min-1 e pré-concentrado durante 120 s. O limite de detecção obtido foi 93 ng L-1 (n=20, 3δ). O desempenho deste sistema foi testado para determinação de mercúrio em água potável, água não potável e sedimentos de lagoa. A confiança de todo procedimento foi confirmada através de testes de recuperação.
An electrochemical procedure for palladium deposition on the inner of a graphite tube for permanent chemical modification and a cold vapor generation system for the determination of trace levels of mercury in water and sediment by atomic absorption spectrometry are proposed. The tubular electrochemical cell for the deposition of palladium was assembled on the original geometry of a graphite tube that operates as the working electrode. A stainless steel tube, positioned downstream from the working electrode, is used as the auxiliary electrode. The potential value applied on the graphite electrode is measured against a micro reference electrode (Ag/AgCl) inserted into the auxiliary electrode. Palladium solutions in acetate buffer (100 milimol L-1, pH=4.70), flowing at 0.5 mL min-1 for 60 min was used to perform the electrochemical deposition. A cold vapor generation system consist of a micro polyethylene reactor and gas-liquid separator flask, total volume of 4.0 mL, that is discarded after each sampling to avoid intercontamination of the samples. Volumes of 1.0 mL of reagent (2.0% m/v NaBH4 in 0.10 mol L-1 of NaOH) and 1.0 mL of reference or sample solutions in 0.25 mol L-1 of HNO3 are carried out to the reactor and gas-liquid separator by using a peristaltic pump. The mercury vapor is transported to the graphite tube electrochemically modified with argon flow (200 mL min-1) and pre-concentrated during 120 s. The detection limit obtained was 93 ng L-1 (n=20, 3δ). The performance of these system was tested for determination of mercury in potable and non-potable water and lake sediments. The reliability of the entire procedure was confirmed by recovery tests.

Styles APA, Harvard, Vancouver, ISO, etc.

26

Anderson, Jennifer C. « INFRARED MICROSPECTROSCOPIC TECHNIQUES FOR THE QUALITATIVE ANALYSIS OF CROSS-SECTIONED RENAL CALCULI AND EMBEDDED MINERALIZED DEPOSITS ». Miami University / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=miami1083332748.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

27

Grigoletto, Tânia. « Dissolução eletrolítica de ligas de alumínio em cavacos e determinação dos elementos constituintes por espectrometria de emissão atômica com fonte de pasma (ICP-OES) ». Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-12032010-100435/.

Texte intégral

Résumé :

Várias ligas de Al em cavacos, com diferentes granulometrias foram dissolvidas de modo convencional, com ataque por água régia. Este tipo de decomposição resulta, muitas vezes, em resíduos sólidos, cujas quantidades dependem dos teores de silício. A fim de se comparar os resultados, procedeuse, com esses resíduos, de dois modos distintos: ou foram desprezados ou foram decompostos com ácido fluorídrico, eliminando-se o silício, dissolvendo-se o restante com ácido nítrico e agrupando-o à primeira solução para a determinação de Fe, Cu, Mn, Mg, Cr, Ni, Zn, Pb, Sn, Ti e Zr por ICP-OES. Foi avaliada a influência de quantidades crescentes de Al na determinação destes elementos e, também, a provável interferência espectral de Cu na determinação do Zn (com e sem separação eletrolítica de Cu). A dissolução eletrolítica de ligas de alumínio em cavacos foi estudada pressionando-os contra um eletrodo de platina para que se comportassem como se fossem o próprio ânodo e a eletrólise ocorresse. Uma célula foi construída utilizando-se um tubo (corpo de seringa de 2,5 mL) com perfurações ao redor da base aberta, onde foi colocada uma malha sintética (perlon) no fundo e, sobre esta, a amostra. Na parte superior foi introduzido um pequeno tarugo de acrílico com um fio de platina passando pelo seu interior e com um orifício por onde passava o fluxo (4,5 mL min.-1) da solução eletrolítica (ácido nítrico diluído). Na extremidade inferior, prendeu-se, com o fio, uma plaquinha, também de platina, que pressionava a amostra. A solução saía pelos orifícios inferiores para um béquer de onde era recirculada e onde estava colocado o cátodo, um fio de Pt (de forma de losango), sendo novamente captada e introduzida na parte superior do tarugo do ânodo. Com esse circuito, foram obtidos bons resultados utilizando-se ácido nítrico 1 mol L-1, corrente de 0,6A e tempo de eletrólise de 10 minutos. Sendo a dissolução parcial, é necessário que se conheçam as porcentagens dos elementos por dissolução ácida total de uma liga de composição similar ou por um material de referência certificado. Normalizaram-se os dados pelas porcentagens conhecidas dos constituintes das ligas. Compararam-se os cálculos feitos dos seguintes modos: 1-) pela razão entre a concentração do elemento com a do Al, também determinada; 2-) pela a razão entre a concentração do elemento com a soma das concentrações de todos os elementos determinados, inclusive o Al; 3-) pela razão entre a concentração do elemento e a soma das concentrações só dos outros elementos, sem o Al. O desvio padrão e o erro relativo para os elementos Fe, Cu, Mg, Ni e Cr, quando em teores > 0,1%, foram < 10%; para teores de Zn < 0,2%, foram menores de 10% e para teor de 4,8% foram < 15%. Já para o Mn, quando em teor > 0,2% foram <10% (exceto para a liga B.C.S.268/1). O desvio padrão relativo para o Zr, com teor ao redor de 0,002% foi <10%. Os resultados para o elemento Pb nas ligas B.C.S. 216/1 e 380 tiveram desvio padrão e erro relativo <10%, mas o mesmo não ocorreu na liga B.C.S. 268/1. O elemento Sn apresentou resultados piores, ao redor de 20%. O elemento Ti só deu bons resultados quando em teor de cerca de 0,2%. Para estas determinações foram avaliadas as dissoluções químicas dos metais nas ligas pelo ácido nítrico em diferentes concentrações e temperaturas. Além disso, foram avaliadas duas outras células para a verificação da possibilidade de dissolução eletrolítica das ligas de Al on-line com a determinação por ICP-OES.
Several aluminum alloys with different chips size were dissolved using aqua regia (HCl:HNO3,3:1). The residues of the dissolution procedure were either rejected or used in silicon volatilization with hydrofluoric acid before determination of Fe, Cu, Mn, Mg, Cr, Ni, Zn, Pb, Sn, Ti and Zr by ICP-OES. The influence caused by crescent amounts of aluminum in the determination of other elements and the probable spectral interference by Cu in determination of Zn (with or without electrolytic separation of Cu) was evaluated. The electrolytic dissolution of aluminum alloys was performed by pressing chips against a platinum electrode for the electrolysis to occur, so that way the chips behaved as the anode. A tube (body of syringe of 2.5mL) with perforations around the open base was used to contain the sample and Pt electrode. The alloy was placed on synthetic wool (perlon) in this tube. An acrylic dowel with a platinum wire across its interior was fixed in the superior part a tube with Teflon film, with an orifice through which the electrolytic solution flowed (HNO3 1 mol L-1; 4.5mL min-1). A platinum dish was fixed at the inferior extremity of the platinum wire to press the sample. The solution came out through the inferior orifices of the tube to a flask, from where it was again captured (with a peristaltic pump) to go into the superior part of the tube. In this flask, a Pt wire cathode was also placed. A current of 0,6A and ten minutes of electrolysis provided good results. Due to the partial dissolution, the knowledge of percentages of previous elements analyzed after total dissolution, or using certified reference material are necessary. The results were normalized by known percentages. The calculations were made by: 1-) the ratio between the concentration of the element determind, with the determined concentration of aluminum; 2-) the ratio between concentration of the element and the sum of the concentrations of the elements determined, including Al; 3-) the ratio between the concentration of element and the sum of the concentrations of the elements determined, without the aluminum. The relative standard deviations and accuracy were <10% for the elements Fe, Cu, Mg, Ni and Cr when the concentrations were >0.1%; for the Zn were 15%, when the concentration >0.2%, and <10% for concentration <0.2%. For Ti with concentration of about 0.1%, were 15%. Relative standards deviations for the Zr, with concentration of 0.002%, were always <10%. The element Pb, Sn and Mn didnt provide good results. For these determinations, the chemical dissolution of the elements with different nitric acid concentrations and temperature was evaluated. Two other cells for the electrolytic dissolution of Al alloys followed by online ICP-OES determination were examined.

Styles APA, Harvard, Vancouver, ISO, etc.

28

Moraes, Maria Carolina Blassioli. « Introdução da técnica de espectrometria de massas com ionização por electrospray para determinação da razão isotópica baseada em complexos de carga simples com ligantes monoisotópicos. Uma nova alternativa para Boro e metais de transição ». Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-15022019-130329/.

Texte intégral

Résumé :

A espectrometria de massas com ionização por electrospray (ES-MS) foi proposta para medidas da razão isotópica de alguns metais de transição e boro através de complexos com carga simples e ligantes monoisotópicos. Vários experimentos combinando estes elementos com iodeto e fluoreto são apresentados. Cloreto e cianeto foram utilizados em estudos sobre o comportamento destes complexos. De um modo geral, os metais geraram picos mais intensos com cloreto e iodeto, já o boro forneceu um cluster abundante como BF4¯. A principal tendência é a formação de espécies com carga simples pela associação dos íons metálicos com os ânions presentes na solução ou pela perda de um ou mais ligantes. Em alguns casos, esta tendência é mais forte que a manutenção do estado de oxidação do metal na fase líquida. Para cobre e ferro, a variação dos estados de oxidação depende do solvente, de outras espécies em solução e das tensões aplicadas ao cone de amostragem. Estes e outros resultados mostram que a quantificação e especiação não são tarefas muito fáceis, mas há a possibilidade de usar a técnica para medidas isotópicas com os complexos formados com os ligantes monoisotópicos. As principais vantagens neste caso seriam a mudança de m/z para região de massa alta, o que diminui as chances de interferência isobárica, e a ausência de hidretos, comumente observados no modo de íons positivos e sem ligantes. O tetrafluoroborato foi proposto para determinações de razão isotópica do boro (10B/11B). Os espectros obtidos em condições brandas mostram-se livres de interferência isobárica e com resolução de linha base na região de m/z 86 e 87, que corresponde a 10BF4¯ e 11BF4¯. Soluções predominantemente aquosas em meio ácido não devem ser armazenadas, pois ocorre a hidrólise BF4¯. Para minimizar o efeito de memória na fonte de íons, um novo contra eletrodo, tipo cross-flow, foi manufaturado e substituiu o contra-eletrodo original do tipo pepper-pot. Além disto, foram feitos estudos sobre a ação de algumas substâncias que formam complexos não voláteis com boro, como manitol, Triton X-100 e amônia. Estas substâncias são comumente usadas para auxiliar na minimização do efeito de memória em ICP-MS. Observou-se uma diminuição no tempo necessário para limpar a fonte de electrospray, mas o resultado não foi satisfatório. Um procedimento alternativo - e bem mais eficaz - é provocar a hidrólise do BF4¯ residual, o que pode ser feito com um spray de ácido sulfúrico 1mmol/L. Descarga corona é um evento raro, mas que altera drasticamente o espectro. Assim, a mediana e o desvio absoluto da mediana (MAD) foram usados como avaliadores da tendência central e do desvio, respectivamente. A influência das tensões da fonte, do detector, e os fluxos dos gases sobre a razão isotópica foram investigados. Nenhum efeito sistemático foi observado, mas existe discriminação de massas que pode ser corrigida por calibração com padrão certificado do National Institute of Standards and Technology (NIST) de ácido bórico SRM 951. Foram realizados estudos de interferência isobárica e supressão da espécie de interesse. Íons comuns como K+, Na+, Mg2+, Ca2+, SO42¯, Br¯ e Cl¯ não causaram interferência isobárica e fracionamento isotópico. A precisão obtida para a medida da razão isotópica para injeções de 5 min de solução 100 µmol/L de B foi tipicamente 0,4 %, que é comparável àquela obtida por ICP-MS e TIMS. O método proposto também permite a quantificação através da diluição isotópica. Como a técnica de electrospray exige uma concentração do analito superior a 10-6 mol/L para obter um pico detectável e não sofrer supressão pelos eletrólitos em solução, um passo importante na análise de amostras é a pré-concentração. Procedimentos de abertura, pré-concentração e eliminação de interferentes catiônicos foram propostos para amostras de solo, sabão em pó e folhas de algodoeiro. Além destes, duas amostras de plantas certificadas para concentração de boro, pelo National Institute of Standards and Technology, foram avaliadas - folhas de pessegueiro e folhas de macieira. Os resultados obtidos foram excelentes, mostrando que o procedimento desenvolvido para a abertura da amostra, pode vir a ser um método bastante simples e eficaz para análise de boro em amostras reais. É claro que dependendo da amostra a matriz será diferente e outros procedimentos precisarão ser tomados.
A negative-mode electrospray ionization mass spectrometry was proposed to study of isotopic measurements some transition metal ions and boron through of complexes with monoisotopoic ligands. Several experiments combining these elements with iodide, fluoride, chloride, and cyanide are presented. Methanol/water was mainly used as the solvent in order to reduce the surface tension and, thus, the voltage at the capillary tip. Some common behaviors could be observed. Metals give more abundant peaks with iodide and chloride, while boron gives an abundant cluster for BF4¯. In general, the complexes are singly charged formed by association of the metal ions with the anions present in the solution or by loss of one or more ligands from species previously present in solution. In some cases, this tendency surpasses the maintenance of the oxidation state of the metal in liquid phase. The interconversion of low and high oxidation states of copper and iron ions depends on the solvent and other species from the solution, but in the gas phase the high oxidation state species can be reduced by collision induced dissociation at low sampling cone voltages. Surprisingly, ferricyanide and ferrocyanide anions render almost the same spectrum. The results suggest that [Fe(CN)6]4¯ lose one electron to a leaving solvent molecule to form [Fe(CN)6]3¯ in the final steps of desolvation. These and other results suggest that, for the ligands studied in this work, quantitation and speciation are not easy tasks, but there is the possibility of to perform isotope ratio measurements with the complexes formed with monoisotopic anions. The main advantages in this case would be the shift of the m/z to high mass region, which diminishes the chance of isobaric interference, and the inexistence of hydrides, commonly observed in the positive mode ES/MS spectra of metal ions and that cause isobaric interference. The use of electrospray mass spectrometry (ES-MS) of tetrafluoroborate solutions was proposed for the determination of the boron isotopic ratio (10B/11B). When a mixture of methanol and water is used as the solvent and neutral to alkaline medium is kept, spectra obtained at mild electrospray conditions show free-of-interference peaks with base-line resolution in the region of m/z 86 and 87, which corresponds to 10BF4¯ and 11BF4¯. The study was carried out on a quadrupolar mass spectrometer Platform II (Micromass, UK). To minimize the memory effect in the ion source, the original pepper pot counter electrode was substituted by a crossflow counter electrode. This geometry reduces the memory effect, but a cleaning process based on mannitol injection assures a suitable background level. Another procedure to eliminate the memory effect could be the hydrolyze of BF4¯ ion using a sulfuric acid spray. Occasional corona discharge corrupts the numerical results, thus median and median of absolute deviations were used as central tendency and dispersion estimators, respectively, because spikes and outliers do not affect them. The influence of the source and detector voltages and the gas flows over the isotopic ratio was investigated. No systematic effect was observed, but there are mass discrimination and drift that were corrected by successive injection of solution of boric acid NIST 951 converted to sodium tetrafluoroborate. Common ions such as K+, Na+, Mg2+, Ca2+, SO42¯, Br¯ and Cl¯ do not cause significant isobaric interference and isotopic fractionation. The isotopic ratio precision obtained for 5-min injection of 100-µmol/L boron solution at 10-µL/min was typically 0.4%, which is comparable to those from induced coupled plasma (ICP-MS) and thermal ionization mass spectrometry (TIMS). Besides, through of isotope dilution it is possible quantitative analysis of boron. Electrospray needs a minimal concentration of analyte, above of 10-6 mol/L, to obtain a detectable peak and it do not suffer suppression of other electrolytes presents in solution. Therefore, an important step in the analyses of real samples is the pre-concentration and elimination of cationic interference. Procedures of dissolution and digestion to soil, washing powder and plants were proposed. Besides, two certified samples of plants from National Institute of Standards and Technology were evaluated- peach leaves and apple leaves. The results obtained were excellent, showing that the procedure developing can be an alternative method to boron analyses.

Styles APA, Harvard, Vancouver, ISO, etc.

29

Damin, Craig Anthony. « Instrument Development and Application for Qualitative and Quantitative Sample Analyses Using Infrared and Raman Spectroscopies ». Miami University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=miami1385774823.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

30

Ishihara, Fumiko. « The use of Hadamard Transform as a data compression technique in the development of a 3-dimensional fluorescence spectral library for qualitative analysis ». Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54201.

Texte intégral

Résumé :

In recent years, chemical instrumentation has become much more sophisticated. Most analytical equipment now incorporates a microprocessor or is interfaced to a microcomputer. As a result, chemists can collect an immense amount of data on a single sample in a short period of time. While there may be an advantage to gathering such a great deal of information, problems can arise from too much information. Today, analysts commonly are faced with the dual problems of storing and analyzing the resulting flood of information. The goal of this research has been to address the problems of data storage and data analysis. Specifically, data compression techniques and spectral search and match algorithms have been developed. The data compression techniques developed utilize the Hadamard Transform and the modified zero-crossing clipping algorithm. The spectral search technique utilizes the unique format of the compressed and clipped data to greatly accelerate spectrum identification. To demonstrate the feasibility of this technique, three-dimensional fluorescence spectra of polynuclear aromatic compounds have been used. The results indicate data compression techniques and the application of these techniques to a library search system for three-dimensional fluorescence spectroscopy were both successful.
Ph. D.

Styles APA, Harvard, Vancouver, ISO, etc.

31

Porfirio, Darilena Monteiro. « Determinação macro e microelementos em adoçantes dietéticos por ICP OES ». Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-08092016-115857/.

Texte intégral

Résumé :

Neste estudo foi determinado o conteúdo de metais em adoçantes dietéticos de mesa, consumidos por um número crescente de pessoas preocupadas em manter a forma física e restringir o nível calórico da dieta havendo ou não recomendação médica. Foram coletadas 26 amostras de adoçantes dietéticos distribuídos no mercado de São Paulo, em uma grande variedade de apresentações, produtos, composições e marcas. Como a composição é dependente da produção, esta análise é indispensável ao controle da qualidade e relevante à saúde do consumidor. A Espectrometria de Emissão Óptica com Fonte de Plasma Indutivamente Acoplado (ICP OES) com vista axial, mostrou-se adequada determinação dos macronutrientes Na, K, Ca, Mg e dos microelementos essenciais Fe, Cu, Zn, Cr, Mn e Se, dos potencialmente tóxicos AI, Ni, As, Cd e Pb em adoçantes sólidos e líquidos, atendendo as exigências da legislação brasileira. Assim, foi realizado um estudo comparativo entre as determinações utilizando as metodologias clássicas de pré-tratamento da amostra, como o resíduo de cinzas, a dissolução ácida com aquecimento por microondas com o procedimento sem tratamento prévio das amostras, visando facilitar a análise, uma vez que esta é a etapa que mais consome tempo e esforços. A determinação simultânea do espectro favoreceu a análise, uma vez que 74 comprimentos de onda puderam ser selecionados sem aumento no tempo ou no custo de análise, auxiliando na seleção de 36 linhas analíticas mais adequadas (livre de interferências) à determinação sem tratamento prévio da amostra. Nenhuma amostra de adoçante excedeu o valor recomendado para o somatório dos contaminantes inorgânicos (Aspartame < 10 µg g-1 e Sacarina < 20 µg g-1). No entanto, 6 marcas de adoçantes em pó excederam o valor limite da legislação para As (1,0 µg g-1), excederam o valor para Cr total (0,1 µg g-1) e 2 marcas de adoçante líquido excederam o valor para Ni (0,1 µg g-1). Mostrando que os adoçantes em pó apresentam (≈5 µg g-1) níveis maiores de metais potencialmente tóxicos que os adoçantes líquidos (≈2,O µg mL-1).
The metal content in artificial sweetener usually consumed by a growing population concerned to keep body shape and to restrict the diet caloric content, by medical recommendation or not, was measured. The samples were 26 artificial sweeteners available at São Paulo\'s market, under different forms, and several suppliers, with various sweetener composition, and brands. Because the composition depends on manufacture factors, this analysis is mandatory for quality control and relevant for the user health. Inductively coupled plasma atomic emission with axial view has demonstrated to be an appropriated technique to determine the macronutrient content, such as Na, K, Ca, Mg and essential microelements such as Fe, Cu, Zn, Cr, Mn and Se, besides the potentially toxic elements such as AI, Ni, As, Cd and Pb in solid and liquid sweeteners in accordance with to the Brazilian regulation. It was also performed a comparative study of the sample preparation methodology, using classical sample pretreatment, such as burning to ashes, and acid dissolution with microwave heating and a procedure without prior sample treatment (dissolution and/or convenient dilution), aiming at facilitating the analysis of dietetic sweetener because this step is the most time and labor consuming. The analysis was simplified using the simultaneous spectra acquisition, once 74 wavelengths were selected without time or cost increase, and helping the identification of 36 appropriate analytical lines (free from interferences) to apply to the samples determination without prior treatment. None sweetener exceeded the recommended value of inorganic contaminant (for aspartame samples the value was below 10 µg g-1 and for saccharine samples that was below 20 µg g-1). However, 6 brands of artificial sweetener in powder exceeded the legislation limit value for As (1.0 µg g-1), and other 7 brands exceeded the Cr recommended maximum value (0.1 µg g-1). Other 2 brands of Iiquid sweetener exceeded the Ni recommended maximum value. Therefore, for ali samples, the artificial sweetener in powder presented higher levels of potentially toxic metais (≈5µg g-1) than those in a Iiquid presentation (≈2.0 µg mL-1).

Styles APA, Harvard, Vancouver, ISO, etc.

32

Siloto, Rita de Cássia. « Especiação de cobre e zinco em água de coco e a influência do processo de pasteurização sobre essas espécies ». Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-06062016-183858/.

Texte intégral

Résumé :

A água de coco é considerada uma bebida isotônica, nutritiva e pouco calórica. A sua composição química é bastante complexa, alguns dos principais constituintes são açúcares e minerais e, em menores quantidades, Iipídeos e compostos nitrogenados. Um grande desafio é preservar a água de coco por longo período de tempo fora do fruto, mantendo as suas características físicas e organolépticas. A pasteurização é um dos processos de conservação que vem sendo utilizado com esse propósito. No entanto, pouco se sabe a respeito da influência desse processo de conservação na composição química da água de coco. Nesse sentido, a proposta desse trabalho foi investigar as espécies químicas de Cu e Zn presentes na água de coco, bem como avaliar a influência do processo de pasteurização sobre essas espécies. Para esse estudo foram feitas medidas de pH e da concentração hidrogeniônica, extração em ponto nuvem, extração por solvente, ultrafiltrações e determinação da concentração total de proteínas visando a separação com eletroforese em gel de poliacrilamida com dodecil sulfato de sódio (SOS-PAGE), e cromatografia por filtração em gel. As determinações de Cu e Zn foram feitas na água de coco total e nas frações por espectrometria de absorção atômica com atomização eletrotérmica (ETAAS). Os resultados das determinações totais de Cu e Zn, e de proteínas mostraram que a composição dessas espécies varia muito entre os diferentes frutos. A combinação dos resultados obtidos pelas diferentes técnicas indicou que o Cu está, preferencialmente, associado às moléculas de maiores pesos moleculares, enquanto que o Zn encontra-se associado a pequenas moléculas. A pasteurização não afetou o pH, a concentração total dos elementos e de proteínas. Porém, a partir dos resultados da cromatografia por filtração em gel e da determinação de Cu e Zn nas frações coletadas do eluente, foi possível observar que a pasteurização provocou alterações nos pesos moleculares das proteínas e, possivelmente nos elementos associados a elas. As mudanças observadas indicam quebra de ligações fracas, provavelmente dissulfeto, rompendo aglomerados protéicos (maior massa molecular) e aumentando a abundância de proteínas mais leves (menor massa molecular).
Coconut water is a natural isotonic, nutritive and low caloric drink. Its chemical composition is quite complex, some of the main compounds are sugars and minerais and, in smaller amounts fat and compounds of nitrogen. The coconut water preservation outside the fruit, maintaining its physical and organolépticas properties is a big challenge. Pasteurization has been used as one of the most common preservation processes. However, little knowledge exists about the influence of preservation processes over coconut water chemical composition. This way, the aim of this work was to investigate the chemical species of Cu and Zn in coconut water and evaluate the influence of pasteurization over these species. For this, many procedures such as, pH measurements, c10ud point extractions, solvent extraction, ultrafiltration, measurement of total protein concentration, sodium dodecil sulphate poliacrylamide gel electrophoresis (SDS-PAGE) and gel filtration chromatography were executed. The Cu and Zn determinations were made in a whole coconut water and in its different fractions, obtained by the separation techniques by using electrothermal atomic absorption spectrometry. The results of Cu, Zn and protein determinations showed that there is a big variation between different fruits. Results obtained by ali techniques used showed that Cu is, preferentially Iinked to big molecules and Zn is associated to small molecules. The results of gel filtration chromatography associated to the concentration of Cu and Zn in the collected fractions showed the strong possibility of Iinkage of these elements with proteins. The pasteurization did not cause significant changes in the total proteins concentration, however, the changes observed indicated the break in week chemical connections, probably in proteins (agglomerations of high molecular mass), increasing the abundance of small proteins (Iow molecular mass).

Styles APA, Harvard, Vancouver, ISO, etc.

33

Espimpolo, Daniela Mica. « Estudo da construção de conhecimento na disciplina de Química Analítica Qualitativa e a inserção de íons de Terras Raras no processo de separação analítica de cátions ». Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/59/59138/tde-18062013-153354/.

Texte intégral

Résumé :

Em atendimento às determinações legais decorrentes da LDB, reestruturações foram introduzidas nos currículos de Química, em especial na disciplina de Química Analítica Qualitativa (QAQ). Tal fato, atrelado à vigente concepção dos estudantes acerca da disciplina de QAQ: a memorização de um grande número de reações químicas; leva à imperativa necessidade de mudanças didático-metodológicas para tornar o processo de ensino e aprendizagem mais efetivo. É importante salientar que as metodologias de ensino, bem como as avaliações do processo de ensino e aprendizagem, sejam adequadas à maneira como ocorre o processo de construção de conhecimentos dos estudantes. Destarte, a contribuição desta pesquisa consiste no estudo do processo de construção do conhecimento na disciplina de Química Analítica Qualitativa. Para tanto, uma Atividade Orientadora de Ensino (AOE) (MOURA) voltada à temática equilíbrio químico em soluções aquosas foi organizada e desenvolvida com os estudantes do terceiro semestre do curso de Licenciatura em Química do Departamento de Química (DQ) da Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP). A pesquisa foi baseada na pesquisa-ação (EL ANDALOUSSI). Os encontros foram videogravados e analisados pautando-se no enfoque Histórico-Cultural (VIGOTSKI) e na Teoria da Atividade (LEONTIEV) considerando, sobretudo, a linguagem. A apresentação da análise foi realizada por meio de episódios (MOURA), nos quais se explicitam a organização do ensino, bem como o movimento de aprendizagem dos estudantes. O princípio geral de separação da marcha analítica a partir da especificidade do teste de ferro(III) com tiocianato e do conceito de solubilidade foram apropriados pelos estudantes. Reagentes de grupo, controle das condições reacionais e o fenômeno de interferência foram igualmente discutidos, possibilitando a internalização destes conceitos pelos estudantes. Foi possível identificar que o processo de construção do conhecimento ocorre por meio de nexos cognitivos, em um constante movimento dialético, propiciado pelas interações estudante-estudante e estudante-professor, de uma dimensão interpsíquica para intrapsíquica. Observou-se que o papel do professor enquanto mediador deste processo foi fundamental. Além disso, a AOE configura-se como uma ferramenta metodológica em potencial para ser utilizada na disciplina de QAQ. O estudo do processo de construção de conhecimento na disciplina de QAQ foi o tema predominante nesta pesquisa e está apresentado na Parte A desta dissertação. Por outro lado, em decorrência do destaque conferido às Terras Raras (TR) no atual cenário socioeconômico mundial, surge uma oportunidade para se trabalhar na construção de conhecimento químico, no caso a inserção do estudo das propriedades destes elementos no currículo de graduação em Química. Dessa forma, parte desta pesquisa destinou-se à investigação da inclusão dos íons de TR (Nd3+ e Pr3+) na marcha analítica e está apresentado na Parte B desta dissertação. Foi possível separá-los junto ao grupo III e posteriormente identificá-los como oxalato de neodímio e oxalato de praseodímio Nd2(C2O4)3 e Pr2(C2O4)3, respectivamente.
In compliance with legal requirements arising from the LDB, restructurings have been introduced in the Chemistry curricula, especially in the Qualitative Analytical Chemistry (QAC) discipline. This fact, together with current concepts of the students about the QAC discipline, mainly the memorization of a large number of chemical reactions, leads to the imperative necessity of didactic and methodological changes in order to make more effective the teaching and learning processes. It is also important to mention that the teaching methodologies, as well as the evaluation of teaching and learning, must be adequate to way in which the construction of the students knowledge takes place. Thus, the contribution of this research is to study the process of knowledge construction in the QAC discipline. Therefore, a Teaching Guiding Activity (TGA) (MOURA) focused on the \"chemical equilibrium in aqueous solutions\" theme was organized and developed with students of the third semester of a Chemistry graduation course, at the Department of Chemistry (DC), of the Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (School of Philosophy, Sciences and Literature of Ribeirão Preto- FFCLRP) of the University of São Paulo. The research was based on action research (ANDALOUSSI EL). The meetings were videotaped and analyzed based on the Historical-Cultural approach (VIGOTSKI) and Activity Theory (LEONTIEV), by considering especially the language. The presentation of the analysis was performed by means of episodes (MOURA), in which they explain the organization of teaching, as well as the movement of the students learning. The general principle of systematic separation of inorganic ions, based on the specificity of the iron(III) test with thiocyanate and on the concept of solubility, have been appropriated for the students. The group reagents, the control of the reaction conditions and the phenomenon of interference have also been discussed, thus allowing for the internalization of these concepts by the students. It has been possible to identify that the process of knowledge construction occurs by means of a cognitive nexus, in a constant dialectical movement, caused by student-student and student-teacher interactions, in an interpsychic-to-intrapsychic dimension. It has also been observed that the teacher´s role as a mediator of this process was essential. In addition, the TGA is configured as a potential methodological tool to be applied in the QAC discipline. The study of the knowledge construction in the QAC discipline was the predominant theme in this research and it is presented in the Part A of this dissertation. Nevertheless, due to the emphasis which is currently placed on Rare Earth elements (RE) in the global socioeconomic scenario, there is an opportunity to work with the construction of the chemical knowledge, for instance, with the inclusion of the study of the properties of these elements in the undergraduate Chemistry courses. Thus, the Part B of this research is devoted to the investigation of the inclusion of RE ions (Nd3+ and Pr3+) in the systematic analysis of inorganic ions. It has been possible to separate the two RE ions along with the Group III, with their further identification as praseodymium(III) and neodymium(III) oxalates Nd2(C2O4)3 and Pr2(C2O4)3, respectively.

Styles APA, Harvard, Vancouver, ISO, etc.

34

Prada, Silvio Miranda. « Caracterização estrutural do complexo Cu(II) / DPKBH e desenvolvimento/aplicação de método espectrofotométrico em fluxo, empregando multicomutação e amostragem binária, para determinação de Cu(II), Fe(II) e Fe(III) ». Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-11032019-103333/.

Texte intégral

Résumé :

Desenvolveu-se um método espectrofotométrico para determinação de íons Cu(II), Fe(II) e Fe(III) com o reagente cromogênico di-2-piridil cetona benzoilhidrazona (DPKBH), em condições estacionárias e em fluxo. Fez-se a caracterização estrutural e estequiométrica do complexo de Cu(II) com DPKBH usando-se técnicas espectroscópicas de infravermelho e massas, além de análise térmica e elementar. Estudou-se, ainda, a estequiometria dos complexos de Fe(II) e Fe(III) com DPKBH utilizando espectrometria de massas com ionização por electrospray. Desenvolveu-se, preliminarmente, um método espectrofotométrico para a determinação de íons Cu(II) com DPKBH e aplicou-se em amostras de aguardente. Posteriormente, adaptou-se para análise por injeção em fluxo, utilizando-se injetor comutador manual. Em seguida, desenvolveu-se em condições estacionárias um método espectrofotométrico para determinação de Fe(II) e Fe(III) e Cu(II) em uma mesma amostra, com o uso de agentes mascarantes. Fez-se também a adaptação do método para análise em fluxo empregando multicomutação e amostragem binária. Finalmente, determinou-se a concentração de íons Cu(II), Fe(II) e Fe(III) em amostras sintéticas e Cu(II) e ferro total em amostras de sedimento coletadas no reservatório de Guarapiranga. Os resultados obtidos foram comparados com o método de referência de ICP-OES, apresentando concordância para um nível de confiança de 95% da média.
A spectrophotometric method was developed to the determination of Cu(II), Fe(II) and Fe(III) with the chromogenic reagent di-2pyridyl ketone benzoylhydrazone (DPKBH) in stationary conditions as a flow injection process. The structural characterization and the stoichiometry of Cu(II)/DPKBH complex were achieved using infrared spectrometry, mass spectrometry, thermal and elementar analysis. Toe stoichiometry of the Fe(II) and Fe(III) complexes with DPKBH was studied by electrospray ionization mass spectrometry. The spectrophotometric method for the determination of Cu(II) with DPKBH was developed in stationary conditions and, after this, it was adapted to flow injection analysis, using a manual commutator. Subsequently, a spectrophotometric method was developed to determine Fe(II), Fe(III) and Cu(II) in the same sample, in stationary conditions, using masking reagents. This method was also adapted to flow injection analysis, using multicommutation and binary sampling. Finally, Cu(II), Fe(II) and Fe(III) were determined in sediments from Guarapiranga reservoir. The obtained results were compared with the ICP-OES standard methods, showing a good agreement into a 95% confidence level (t-test).

Styles APA, Harvard, Vancouver, ISO, etc.

35

Galhardo, Cristiane Xavier. « Potencialidade da injeção seqüencial no monitoramento em tempo real de indicadores de qualidade de águas naturais e residuais ». Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-10102014-131230/.

Texte intégral

Résumé :

O presente trabalho apresenta o desenvolvimento de metodologias baseadas no sistema de Análise por Injeção Seqüencial (SIA) para a determinação de fosfato e silicato, nitrito e nitrato, assim como a especiação de Fe(II) e Fe(III) em amostras de interesse ambiental, com ênfase para sistemas aquáticos. Para todas as determinações utilizou-se a espectrofotometria de absorção molecular na região do visível como técnica de detecção. A determinação de fosfato e silicato foi baseada na reação de ambos os ânions com molibdato de amônio em meio ácido e posterior redução do Mo(VI) à Mo(V) com ácido ascórbico. O procedimento SIA foi desenvolvido para contornar a interferência mútua das duas espécies explorando o efeito de complexação do molibdato pelo ácido oxálico. A determinação de nitrito foi baseada na reação de diazotação com sulfanilamida e diclorato de N-1 naftil etilenodiamina (NED), enquanto a determinação de Fe(II) baseou-se na sua complexação com 1,10 fenantrolina. A determinação de nitrato e Fe(III) foi efetuada pelas mesmas reações após a redução a nitrito e Fe(II) em colunas de cádmio e zinco amalgamado, respectivamente. A estabilidade das curvas analíticas foi avaliada em diferentes dias de trabalho, obtendo-se variações não superiores a 5% durante um período de 4 dias. O sistema de injeção seqüencial foi explorado também no sentido de regenerar as colunas redutoras no intervalo de tempo entre duas amostras. A estabilidade das curvas analíticas, a viabilidade de regeneração das colunas redutoras e a possibilidade de realizar a amostragem através de filtração tangencial, permitindo a realização de análises com características de tempo real, sugerem que o sistema de injeção seqüencial tem grande potencial para ser implementado em estações automáticas de monitoramento da fração solúvel de indicadores de poluição em águas naturais e residuais.
The present work presents the development of analytical methodologies based on Sequential Injection Analysis (SIA) for determination of phosphate and silicate, nitrite and nitrate, as well as speciation Fe(II)/Fe(III) in environmental samples with emphasis for aquatic environments. All determinations were performed using molecular absorption spectrophotometry at the visible range of the spectrum as the detection technique. The determination of phosphate and silicate was based on the reaction of both anions with ammonium molybdate in acidic medium, followed by reduction of Mo(VI) to Mo(V) with ascorbic acid. The SIA procedure was developed to avoid the mutual interference of both species exploiting the complexation of the molybdate by oxalic acid. The determination of nitrite was based on the diazotation reaction with sulfanilamide and N-l naphtyl ethylenediamine dihydrochlorine (NED), while the determination of Fe(II) were based on the complexation with 1,10 phenantroline. The determination of nitrate and Fe(III) were based on the same reactions, performed after their reduction to nitrite and Fe(II) in reducing columns containing cooperized cadmium and amalgamated zinc, respectively. The stability of the analytical curves was evaluated in different working days, in which no variations greater than 5% were observed during a period of 4 consecutive days. The sequential injection analysis was exploited to regenerate the reducing columns in the time interval between two sample. The stability of the analytical curves, the easy and automatic regeneration of the reducing columns, as well as the possibility to perform sampling through tangential filtration, which permits the analysis to be performed in real time, are characteristics that show the potential application of the sequential injection systems in automatic stations for monitoring the soluble fraction of pollution indicators in natural waste waters.

Styles APA, Harvard, Vancouver, ISO, etc.

36

Retief, A. C. « Analysis of sterols and sterolins in hypoxis hemerocallidea and related herbal medicine ». Diss., 2002. http://hdl.handle.net/2263/23081.

Texte intégral

Résumé :

Phytosterols and their glucosides (sterolins) have many therapeutic indications e.g. immune modulation, hypercholesterolaemia and benign prostatic hyperplasia (BPH). In this study sterolslsterolins in three BPH phytotherapeutics (Hypoxis hemerocallidea, Prunus africana and Serenoa repens) and related products were investigated. The aim of this study was to develop, evaluate and apply TLC and HPLC methods for the qualitative and quantitative analyses of sterols and sterolins. A new optimum TLC method was developed for good visibility and separation of phytosterols and sterolins and could be used to qualitatively compare sterol/sterolin content. A published HPLC method to determine the bioavailability of β-sitosterol in humans was used in a new application to quantitatively determine phytosterols in plant extracts. A new and sensitive method to determine hypoxoside (norlignan diglucoside unique to Hypoxidaceae), by isolation from the crude methanol extract with solid phase extraction (SPE) and HPLC quantification using fluorescence detection (excitation wavelength of 230 nm and emission wavelength of 345 nm), was developed. The developed TLC and adapted HPLC methods were applied to determine the stability of phytosterols, subjected to increased temperature and gamma irradiation. Phytosterols in isolated form were more stable than the phytosterols in plant material. The data from the accelerated stability tests could be used to estimate the shelf-lives of the BPH phytotherapeutics and related sterol containing products. The HPLC method to determine β-sitosterol in serum, was evaluated during a pilot study of a clinical trial, to test the bio-equivalence of different phytosterol containing products. The method was found not sensitive enough to determine β-sitosterol in serum, notwithstanding improvements made, Le. changing the extraction ratio; experimenting with higher dosages, and different products. As result, the proposed clinical trial could not be performed, in the future, serum could rather be analysed by gas chromatographic methods. TLC and HPLC analyses of medicinal African potato tea, indicated that it contained hypoxoside, but not β-sitosterol or β-sitosterolin. β-Sitosterol (accepted to be the active of H. hemerocallidea) might not be the main active in African potato tea. Hypoxoside and a compound (red spot compound), noticed on TLC plates of acetone extracts of Prunus africana, Serenoa repens, Moducare®, Harzol®, Immunochoice® and Nutricare®, were extracted with water. This general presence of the red spot compound could point to a possible important function. Preparative TLC was unsuccessful to isolate the red spot compound, but column chromagraphy was successfully applied. From the proton and carbon NMR spectra, it was concluded, that the compound was definitely not a steroid and could either be a coumarin or an isoflavanoid, with a sugar unit (possibly a rhamose) attached to it. Further analyses to elucidate the structure failed due to decomposition of the compound. Further work on structure elucidation is required and possible therapeutic activity should also be investigated. The sterols and sterolins in H. hemerocallidea and related herbal medicine can be qualitatively and quantitatively analysed with the developed TLC and adapted HPLC methods. This provides natural medicine industry with necessary procedures to ensure proper quality, safety and stability.
Dissertation (MSc (Pharmacology))--University of Pretoria, 2006.
Pharmacology
unrestricted

Styles APA, Harvard, Vancouver, ISO, etc.

37

Ward, Jessamyn. « Surface-enhanced Raman spectroscopy (SERS) for the qualitative analysis of synthetic piperazines ». Thesis, 2017. https://hdl.handle.net/2144/26942.

Texte intégral

Résumé :

Designer drugs are some of the most commonly abused substances in the world. They are synthesized through slight chemical modifications of existing substances, evading the law while maintaining the desired effects of the pharmaceutical or illicit substance. These drugs are often marketed as “herbal” or “natural,” but are fully synthetic. Due to their constant, rapid emergence, there is a need for a rapid method of identification, both in the field as well as in the laboratory. One group of these designer drugs are synthetic piperazines. Named for the piperazine ring found in their chemical structures, synthetic piperazines are central nervous system stimulants that have the reputation of mimicking the psychoactive effects of the illicit compounds amphetamine and 3, 4-methylenedioxymethampetamine (MDMA). Over the past 10 years, synthetic piperazine cases submitted to forensic laboratories in the United States have greatly increased, including a 30-fold increase between 2007 and 2009 alone. Surface enhanced Raman spectroscopy (SERS) was investigated as a method for the rapid qualitative analysis of synthetic piperazines. SERS is a type of vibrational spectroscopy, which utilizes the interaction of light and matter to elucidate details of the chemical structure of a molecule. SERS combines laser spectroscopy with the optical properties of metallic nanostructures, resulting in strongly enhanced signals from the Raman scattering of light. Each chemical structure will give a unique SERS spectrum and this, coupled with the minimal-to-no sample preparation and the portability of a SERS instrument, makes SERS a strong candidate for the identification of not only synthetic piperazines, but all designer drugs. To evaluate the use of SERS for the qualitative analysis of synthetic piperazines, eight synthetic piperazines were adsorbed onto a SERS substrate. The interaction with the gold nanoparticles enhanced the Raman scattering for all eight of the synthetic piperazines and SERS spectra were obtained. All eight drugs were found to give a robust and reproducible signal, requiring a fewer number of scans, less laser power, and less time for analysis compared with traditional Raman spectroscopy. When compared with traditional Raman spectra, the synthetic piperazines demonstrated sensitivity enhancement factors of up to 10^8 using SERS. A partial least squares-discriminant analysis (PLS-DA) statistical model was built and used to evaluate the analytical sensitivity and specificity of the SERS method. The PLS-DA model helped determine a limit of detection of 10 μg/mL of BZP. All eight synthetic piperazines could be identified by the statistical model below an error rate of 20% when compared to each other- a strong indication of a method with high specificity.Through this research, it has been demonstrated that SERS can be applied efficiently as a qualitative technique for the analysis of synthetic piperazines.

Styles APA, Harvard, Vancouver, ISO, etc.

38

Dykstra, Andrew Boissy. « Advanced Techniques in Mass Spectrometry for Qualitative and Quantitative Protein Characterization ». 2011. http://trace.tennessee.edu/utk_graddiss/1073.

Texte intégral

Résumé :

Though mass spectrometry has earned a central role in the field of proteomics due to its versatility in a wide range of experiments, challenges and complications are still encountered when using mass spectrometry to characterize protein structures, post-translational modifications (PTMs), and abundances. In this dissertation, analytical methods utilizing mass spectrometry have been developed to address challenges associated with both qualitative and quantitative protein characterization. The effectiveness of using multiple pepsin-like proteases, both separately and in mixtures, combined with online proteolysis using a special triaxial probe has been demonstrated on an amyloid beta peptide related to the onset of Alzheimer’s disease. These findings have broad implications in protein structural characterization studies using hydrogen-deuterium exchange mass spectrometry. A wider range of proteases (Lys-C, Glu-C, and trypsin) and multiple fragmentation methods (collisionally activated dissociation, electron transfer dissociation, and decision tree) have been utilized in the discovery-based PTM characterization of extracellular cellulosome proteins of the bioenergy-relevent organism Clostridium thermocellum, resulting in the identification of 85 previously unknown modification sites in 28 cellulosome proteins. These modifications may contribute to the structure and/or function of the cellulosome protein complex. By using peptide internal standards and a triple quadrupole mass spectrometer operating in selected reaction monitoring mode, a method has been developed for the absolute quantitation of the Clostridium thermocellum cellulosome protein machine in samples ranging in complexity from purified cellulosome samples to whole cell lysates as an alternative to a previously-developed enzyme-linked immunosorbent assay method of cellulosome quantitation. The precision of the cellulosome mass concentration in technical replicates is better than 5% relative standard deviation for all samples, indicating high precision of cellulosome mass concentration for this method. Though methods and results presented in this dissertation have implications in the study of Alzheimer’s disease and bioenergy research, more broadly this dissertation focuses on development of methods to contend with some of the more complex challenges associated with protein characterization currently presented to the field of proteomics.

Styles APA, Harvard, Vancouver, ISO, etc.

39

Moore, Amanda Marie. « Qualitative identification of fentanyl and other synthetic opioids using ambient ionization high resolution time-of-flight mass spectrometry ». Thesis, 2017. https://hdl.handle.net/2144/23836.

Texte intégral

Résumé :

The Centers for Disease Control and Prevention deemed the increase in overdose fatalities, due to the use of opioids, an “opioid epidemic” in the United States. Heroin, fentanyl, and other synthetic opioids are commonly abused and are contributing to the opioid epidemic. In 2016, the Drug Enforcement Administration temporarily placed three fentanyl analogs (beta-hydroxythiofentanyl, butyryl fentanyl, and furanyl fentanyl) under Schedule I due to their imminent threat to public health. These drugs elicit analgesic effects similar to heroin making them desirable drugs to abuse. Novel fentanyl analogs and designer opioids are expected to become more prominent in forensic casework in the near future as the opioid epidemic continues. These drugs can be seen in forensic seized drug and urine casework samples either alone or mixed with other drugs of abuse. It is therefore necessary to have an efficient methodology to identify these new compounds. Currently, gas chromatography-mass spectrometry (GC/MS) is used to identify drugs of abuse and is considered the “gold standard” in forensic casework. However, analysis times can often range from 15 to 60 minutes in length. Another drawback is the need for spectral library matching, which requires analytical reference materials for identification. Therefore, the identification of novel fentanyl analogs and designer drugs is limited until a reference material becomes available. In this study, direct sample analysis time-of-flight mass spectrometry (DSA-TOFMS) was evaluated to provide rapid identification of fentanyl and other synthetic opioids in seized drug and urine casework samples. DSA is a direct ambient ionization source, which requires no chromatography and minimal sample preparation. TOFMS is a high resolution mass spectrometer that uses collision-induced dissociation (CID) to produce precursor ion and characteristic fragmentation ions, which provide additional structural and molecular formula information, allowing for the identification of compounds without a reference material. The analytes explored in this study include: heroin, 6-monoacetylmorphine (6-MAM), morphine, fentanyl, norfentanyl, 4-anilino-N-phenethylpiperidine (4-ANPP), acetyl fentanyl, beta-hydroxythiofentanyl, butyryl fentanyl, furanyl fentanyl, valeryl fentanyl, AH-7921, U-47700, buprenorphine, norbuprenorphine, desomorphine, MT-45, W-15, and W-18. Direct sample analysis time-of flight mass spectrometry (DSA-TOFMS) is a novel instrumentation that could be utilized in the forensic sciences field to qualitatively identify illicit substances in casework samples. In this study, 19 compounds of interest containing heroin, fentanyl, fentanyl analogs, and other synthetic opioids were evaluated using DSA-TOFMS. DSA-TOFMS abbreviated the workload of the analysis and was utilized to provide precursor ion and characteristic fragmentation ions within an analysis time of 20 seconds. Certified reference standards were used to optimize instrumentation settings, to determine precursor ions and characteristic fragmentation ions, and to determine the limit of detection of the instrument. A carryover study determined there were no persisting ions present when entering the capillary inlet between runs. A repeatability study revealed the DSA-TOFMS repeated results within the acceptable criteria range of above 500 counts and within 10ppm error 93% (10ppm) and 83% (1ppm). Forensic seized drug casework samples were evaluated with DSA-TOFMS and qualitatively identified. Out of the 64 samples, 89% were qualitatively identified as heroin, 4% were qualitatively identified as fentanyl, 1% was qualitatively identified as heroin and fentanyl, 3% were qualitatively identified as acetyl fentanyl, and 3% were qualitatively identified as furanyl fentanyl. The casework samples containing furanyl fentanyl were considered “true unknown unknown samples,” as the Maine Health and Environmental Testing Laboratory gas chromatography-mass spectrometry library did not have a spectrum to use for the identification of these samples. Forensic urine casework samples were evaluated with DSA-TOFMS. Samples previously confirmed to contain compounds of interest were prepared using minimal sample preparation technique (filtered using 0.45 microns syringe filters and diluted (1:10) with LC/MS grade water). Analysis displayed the limitations of DSA-TOFMS as only twelve of the forty compounds of interest were present and only three of the twelve were within the acceptable criteria range. DSA-TOFMS is a fast and reliable technique with minimal sample preparation for forensic seized drug samples. However, the concentration in complex matrixes, such as urine and blood, were unable to be qualitatively identified using this sample preparation method by DSA-TOFMS.

Styles APA, Harvard, Vancouver, ISO, etc.

40

Moretto, Giovanna Lucia. « A study into the use of ion beam analysis for the quantitative and qualitative analysis of conducting polymers : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry at Massey University, Palmerston North, New Zealand ». 2004. http://hdl.handle.net/10179/1620.

Texte intégral

Résumé :

Since their discovery in the late 1970s conducting polymers have become increasingly used materials in many applications. They are utilised for their conductivity and/or their electroactive properties. These applications include sensor technologies, actuators, and battery materials. The properties of conducting polymers rely on the extent of the reduction / oxidation or redox state, and hence the dopant levels, of the materials. The aim of this work was to investigate the use of the Ion Beam Analysis (IBA) techniques Rutherford Backscattering Spectroscopy (RBS), and Proton Induced X-ray Emission (PIXE) for the analysis of 'soft' organic materials, in particular, conducting polymers. These IBA techniques are not new, as they have been extensively used for the characterisation of many inorganic, 'hard', materials such as aluminium oxide and silicon oxynitride. While they have been used to alter the molecular structure, and hence the properties of conducting polymers in the past, little to no research has explored the use of ion beams as a tool for the characterisation of these materials. Conducting polymers can either be prepared chemically or electrochemically. They are predominantly prepared in an oxidised state and this charge is balanced by negatively charged counter ions. In this work, the conducting polymers were formed electrochemically by deposition onto support materials at constant electrode potential. The number of counter ions required to balance the polymer chain depends on the type of conducting polymer formed and extent of oxidation. Issues such as the influence of the support material and extent of polymer oxidation on the extent of counter ions through the polymer films are of importance. Gaining knowledge of the dispersion of counter ions may provide new insights into the redox mechanisms for conductive polymers. Complex bis terthiophene porphyrin conducting polymers were prepared and investigated for the uptake of zinc into the freebase porphyrin unit after polymerisation by acquiring elemental depth profiles using RBS analysis. Issues such as the influence of the support material and extent of polymer oxidation on the extent of counter ions through the polymer films were found to be of importance. Gaining knowledge of the extent of counter ions provides new insights into the redox mechanisms for conductive polymers. The results were compared to those obtained for a sample where zinc was coordinated to the porphyrin prior to the polymerisation process. Unexpected high concentrations of both nitrogen and oxygen were found, which were interpreted to be due to entrapped cations originating from the electrolyte ((Bu)4N+), together with trapped water molecules, within the polymer films. The chlorine depth profiling assisted with understanding the extent of the perchlorate counter ion throughout the polymer films. The combination of both RBS and PIXE demonstrated that trace element impurities can be detected using ion beam analysis, which other analytical techniques are unable to do. A series of polypyrrole films incorporating a range of counter ions were prepared as model compounds for study in the second section of this work. RBS and PIXE techniques were used to evaluate film homogeneity with respect to depth and to infer the counter ion / pyrrole unit ratio for each of the six PPy film formed. RBS was also used to characterise a series of terthiophene-ferrocene based conducting co-polymers. The ratio of co-polymer monomer to terthiophene-ferrocene monomers and the dopant levels for the polymers were determined using a RBS deconvolution method developed in this study. This new method can be extended for characterization of a wide range of organic polymers. The limitations of RBS for the analysis of these soft materials were identified. The advantage that RBS offers over other analytical techniques is that it provides a means for low atomic number element depth profiling in these materials.

Styles APA, Harvard, Vancouver, ISO, etc.

41

Wilson, Sarah Beth. « A comparison of first-semester organic chemistry students' experiences and mastery of curved-arrow formalism in face-to-face and cyber peer-led team learning ». Thesis, 2015. http://hdl.handle.net/1805/10082.

Texte intégral

Résumé :

Indiana University-Purdue University Indianapolis (IUPUI)
The cyber Peer-Led Team Learning (cPLTL) workshops are a synchronous online adaptation of the educational intervention PLTL, in which students, under the guidance of undergraduate peer facilitators, collaboratively solve problems in small groups. The purpose of this parallel convergent mixed methods study was to assess the impact of implementing cPLTL in an organic chemistry course on students’ workshop experiences, performance, and development of curved-arrow formalism skills. Statistical analyses revealed comparable attendance rates, distribution of course grades, and achievement on American Chemical Society First-semester Organic Chemistry Exams. However, plotting workshop grades by AB, C, and DFW grade groupings revealed that PLTL students earned more successful grades than their cPLTL counterparts (91% vs 77% ABC grades). Utilization of a new curved-arrow formalism analytic framework for coding student interview artifacts revealed that cPLTL students were statistically less likely to successfully draw the product suggested by the curved-arrows than their PLTL classmates. Both PLTL and cPLTL students exhibited a comparable incidence of relational to instrumental learning approaches. Similarly, both PLTL and cPLTL students were more likely to exhibit a common Scheme for Problem-Solving in Organic Chemistry (SPOC) than having dialogue that could be characterized by Toulmin’s Argumentation scheme. Lastly, implications for faculty are suggested, including: developing more explicit connections concept, mode, and reasoning components of understanding curved-arrow formalism for organic chemistry students; optimizing graphical collaborative learning activities for online learners; and developing online students’ sense of community.

Styles APA, Harvard, Vancouver, ISO, etc.

Thèses sur le sujet « Qualitative Analytic Chemistry »

Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres