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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Desenvolvimento e validação de metodologias analíticas para quantificação de β-escina em extratos de Aesculus hippocastanum L. (Castanha da Índia)

Dutra, Lidiane Silva 25 July 2012 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-06-27T18:35:12Z No. of bitstreams: 1 lidianesilvadutra.pdf: 2190672 bytes, checksum: 0b5887c354de6e34ac0de42130ae2653 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-06-27T18:39:39Z (GMT) No. of bitstreams: 1 lidianesilvadutra.pdf: 2190672 bytes, checksum: 0b5887c354de6e34ac0de42130ae2653 (MD5) / Made available in DSpace on 2016-06-27T18:39:39Z (GMT). No. of bitstreams: 1 lidianesilvadutra.pdf: 2190672 bytes, checksum: 0b5887c354de6e34ac0de42130ae2653 (MD5) Previous issue date: 2012-07-25 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Todos os povos do mundo fazem uso de plantas medicinais ou de seus derivados, para o tratamento de doenças. Os fitoterápicos são medicamentos obtidos empregando-se, como princípio ativo, exclusivamente matérias-primas vegetais e são caracterizados pelo conhecimento da eficácia e dos riscos de seu uso. No Brasil estes produtos são regulamentados pela Agência Nacional de Vigilância Sanitária (ANVISA) e devem apresentar qualidade, segurança e eficácia. A β-escina é o principal princípio ativo das sementes da Castanha-da-Índia, Aesculus hippocastanum (Hippocastanaceae) que possui propriedades farmacológicas que produzem respostas significativas nos casos de insuficiência venosa crônica (IVC), hemorróidas e edemas pós-operatórios. Como produto de uso farmacêutico é amplamente utilizada e possui várias apresentações, em diferentes formas farmacêuticas. A Castanha-da-Índia (Aesculus hippocastanum L.) é a segunda espécie vegetal com maior número de derivados registrados como fitoterápicos simples pela ANVISA. A ausência de metodologia analítica para quantificação de β-escina nos extratos fluido, glicólico e seco de Castanha-da-Índia gerou a necessidade de desenvolvimento deste trabalho que teve como objetivos propor e validar métodos analíticos de doseamento para esta substância. Foram desenvolvidas três metodologias analíticas diferentes utilizando a espectrofotometria Ultravioleta visível, Cromatografia Líquida de Alta Eficiência e Eletroforese Capilar. O extrato fluido foi analisado pelas três técnicas validadas. Os métodos foram comparados através do teste t de Student e apresentaram diferenças estatísticas num intervalo de 95% de confiança. O Intervalo de confiança dos métodos também foi calculado, sendo estes de 0.16 a 0.73; 0.21 a 0.87 e 0.24 a 1.15 respectivamente para CLAE, CE e UV-Vis. O teor declarado pelo fabricante foi de 0.47%, estando este valor contido no intervalo de confiança de todas as metodologias. / All people around the world use medicinal plants, or its derivatives, for disease’s treatment. The herbal medicines are obtained by using, as an active principle, only raw vegetables and characterized by knowledge of the effectiveness and risks of its use. In Brazil, these products are regulated by the Agência Nacional de Vigilância Sanitária (ANVISA) and shall provide criteria for quality, safety and efficacy required. The β-escin is the major active proved from seeds of Horse-Chestnut, Aesculus hippocastanum (Hippocastanaceae) that has pharmacological properties that produce significant responses in cases of chronic venous insufficiency (CVI), hemorrhoids and edema postoperatively. As a product for pharmaceutical use is widely used and has several presentations, on various pharmaceutical forms. The Horse-Chestnut (Aesculus hippocastanum L.) is the second plant species with the highest number of derivatives recorded as simple herbal medicine at ANVISA. The lack of analytical methodology for quantification of β-escin in fluid extracts, glycolic and dry of Horse-Chestnut prompted the need for development of this study whose aim was to develop and validate analytical methods for determination of this substance. We developed three different analytical methodologies using UV visible spectrophotometer, High Performance Liquid Chromatography and Capillary Electrophoresis. The fluid extract was analyzed by three techniques validated. The methods were compared using Student's t test and showed statistical differences in the 95% confidence. The confidence interval of the methods was also calculated, which are 0.16 to 0.73, 0.21 to 0.87 and 0:24 to 1:15, respectively, for HPLC, CE and UV-Vis. The amount declared by the manufacturer was 0.47%, while this value in the confidence interval of all methodologies.
12

Charakterizace rostlinné složky vybraných potravin pomocí technik molekulární biologie a instrumentálních metod / Characterization of plant-based component of selected foodstuffs using techniques of molecular biology and instrumental methods

Tomíšek, Martin January 2020 (has links)
The aim of this work was to compare authenticity analysis in selected food products with fruit component by using, instrumental and molekular methods. Particularly, the presence of blueberries in fruit–based foodstuffs was verified. The theoretical part is focused on the characterization, chemical composition and botanical classification of blueberries (European blueberry and Canadian blueberry). It also contains an overview of instrumental and molecular diagnostic methods that can be used for the analysis of these fruits. The experimental part focuses on the selection of a suitable method of DNA isolation, and primers for the detection of blueberries in commercial products. DNA analysis was performed by qPCR and HRM analysis. In the experimental part, DNA was isolated in sufficient quality for PCR and the presence of blueberries in foodstuffs was verified by qPCR. Using HRM analysis, we were able to differentiate between bilberry (Vaccinium myrtillus) and blueberry (Vaccinium corymbosum) in control samples and in some commercial products. Certain phenolic acids and some flavonoids specific for blueberries were detected by HPLC. The total content of polyphenols and flavonoids was determined by UV / VIS spectrophotometry.
13

Možnosti přípravy kombinovaných nápojů z vybraných druhů ovoce / Possibilities of preparation combined drinks from selected fruits

Zábranská, Miroslava January 2016 (has links)
This thesis deals with the preparation of the combined alcoholic beverages based on wine and fruit juices. The fruit juices were obtained from the selected fruits as honeysuckle, mulberry, dogwood, rose hips, elderberry, buckthorn and aronia. Some chemical properties e. g. total fenolics, total anthocyanins, vitamin C and sacharides were determined for characterization of the mentioned juices. As well as chemical parameter of juices, the same chemical parameters were determined on wine. There were prepared three sets of combined beverages from wine and juices. The two best evaluated beverages were chosen on the basis of their sensory evaluation. In the end, the same chemical properties were determined in both particular juices and resulting beverages.
14

Saponin Removal from Quinoa by Abrasion Processing

Lundberg, Luke 01 June 2019 (has links) (PDF)
Quinoa is coated with a thin layer of saponins, glycosylated triterpenoids, that produce a bitter flavor when consumed. The average saponin content in commercial varietals from Bolivia average around 2.7% saponins and organoleptic testing shows the threshold for noticing a bitter flavor is below 0.12% (Medina-Meza et al., 2016). Current industrial processing methods use a combination of abrasion and turbulent water flow to remove saponin. This study will address the following research question: How will grain-to-grain and grain-to-surface abrasion affect the processing time to remove saponin from quinoa? In particular, can effective saponin removal be achieved in less than 10 minutes without washing with water? Three different laboratory scale systems for generating grain-to-grain abrasion alone and in combination with grain-to-surface abrasion were constructed. Preliminary studies using mass balance and visual observation found the tubular system removed 4.45% of the quinoa mass in saponin containing fractions compared to the conical system (1.33%) and fluidized bed (0.62%). After preliminary studies, a saponin estimation method was adapted and the conditions of the tubular system were determined. A randomized experiment was carried out in triplicate at three levels of time (5, 10, and 15 minutes) and mass (200, 300, and 400 grams). The effect of surface roughness in the tubular system was also evaluated. The samples were collected and saponin content in each sample was quantified using the adapted method. The saponin levels were compared to commercially processed quinoa in the market. The processing conditions of 15 minutes at an input mass of 300 grams yielded the lowest saponin level of 0.19%. The four processing conditions of (10 minutes/200 grams, 10 minutes/400 grams, 15 minutes/200 grams and 15 minutes/300 grams) were statistically different (p The tubular system showed promise for reducing process time and saponin content in commercially processed quinoa without washing. However, further experimentation is needed for industrial implementation. The system would provide the industry with a sustainable process with better saponin removal capacity.
15

Comparação entre analisadores com fluxo constante ou pulsado: aplicação a amostras de relevância farmacêutica, agronômica e/ou ambiental / Comparison of flow analyzers exploiting constant or pulsed flows: application to samples of pharmaceutical, agronomical and/or environmental relevance

Sasaki, Milton Katsumi 24 November 2015 (has links)
Sistemas de análises químicas em fluxo com multi-impulsão empregam bombas solenoide como unidade propulsora de fluidos, as quais proporcionam fluxos pulsados. Estes provêm um eficiente transporte radial de massas, o que garante boa homogeneização das soluções envolvidas, mesmo em situações de dispersão limitada. O objetivo principal deste trabalho foi então comparar o desempenho de metodologias envolvendo reagentes imobilizados em sistemas de análises em fluxo com fluxos constantes ou pulsados. Para isto, foram selecionadas as determinações espectrofotométricas de ácido ascórbico em produtos farmacêuticos, utilizando reator tubular de polietileno (50 cm) com MnO2(s) imobilizado, e reação com formaldoxima (0,25 mol L-1); e de carbaril em águas naturais, explorando extração líquido-líquido com xileno imobilizado em membrana de PVDF, e solução de NaOH a 0,1 mol L-1 como fluxo aceptor. Adicionalmente, compararam-se os dois tipos de fluxo em uma nova titulação em fluxo, a titulação monitorada por traçador; a determinação de acidez total em vinagres foi selecionada e utilizaram-se as titulações por injeção em fluxo e programada em triângulo, ambas empregando solução de NaOH a 0,01 mol L-1 como titulante e fenolftaleína como indicador ácido-base, com monitoramento por traçador empregando azul brilhante FCF (ca. 6 mg L-1). Na determinação de ácido ascórbico, o desempenho do sistema com fluxos pulsados foi superior àquele com fluxos constantes quanto ao limite de detecção: 0,33 contra 0,60 mg L-1 (critério 3,3 ?), e à repetibilidade: d.p.r. estimado como 2,5 contra 5,6% (n = 20); quanto à exatidão, não foi encontrada diferença estatisticamente significativa entre o método proposto e o da Farmacopeia Britânica ao nível de confiança de 95%. Na determinação de carbaril, o uso de fluxos pulsados favoreceu a extração do analito, obtendo-se uma sensibilidade 9,3% maior relativamente ao emprego de fluxos constantes, além de uma melhor linearidade da curva analítica; entretanto, o método mostrou-se susceptível a interferência de outros metilcarbamatos, o que comprometeu sua aplicação à análise de águas naturais. Na determinação de acidez total, a exploração de fluxos pulsados proporcionou menores variações da razão dos valores de absorbância relativos ao monitoramento do traçador e do indicador; não foi encontrada diferença estatística entre as titulações em fluxo propostas e o método titulométrico de referência ao nível de confiança de 95% / Multi-pumping flow systems use solenoid pumps as fluid propelling devices, which deliver pulsed flows. These flows provide an efficient radial mass transport, thus good mixing conditions even in limited sample dispersion situations. The main objective of this work was then to compare the performance of methodologies involving immobilized reagents in flow systems with constant or pulsed flows. To this end, the spectrophotometric determinations of ascorbic acid in pharmaceutical products using a 50-cm polyethylene tubular reactor with immobilized MnO2(s) with further colour-forming reaction with 0.25 mol L-1 formaldoxime; and carbaryl in natural waters exploiting liquid-liquid extraction with xylene immobilized in a PVDF membrane and a 0.1 mol L-1 ¬¬NaOH solution as acceptor stream, were selected. Moreover, constant and pulsed flows were compared in relation to a novel strategy for flow titration, named tracer-monitored titration; the determination of total acidity in vinegars was selected and flow injection and triangle-programmed titrations were applied, both using a 0.01 mol L-1 NaOH solution as titrant, phenolphtalein as acid-base indicator and ca. 6 mg L-1 brilliant blue FCF as tracer. Regarding ascorbic acid determination, the pulsed flow system was superior in relation to the constant flow system for detection limit: 0.33 against 0.60 mg L-1 (3.3 ? criterion), and for repeatability: r.s.d. estimated as 2.5 against 5.6% (n = 20); in relation to accuracy, no significant differences between the proposed method and that of the British Pharmacopoeia were found at the 95% confidence level. Regarding carbaryl determination, use of pulsed flows favored the analyte extraction, leading to a 9.3% sensitivity improvement in relation to use of constant flows; besides the attainment of better linearity of the analytical curve. The method was however susceptible to interference of other methylcarbamates, thus the application to natural water analyses was impaired. Regarding total acidity determination, pulsed flows exploitation provided lower variations in the ratio of absorbance values related to the monitoring of tracer and indicator; no significant differences between the proposed titrations and the reference method were found at the 95% confidence level
16

Projeto e desenvolvimento de um sistema de análises químicas por injeção em fluxo para determinações espectrofotométricas simultâneas de cobre e de níquel explorando cinética diferencial e calibração multivariada / Project and development of a flow-injection system for simultaneous spectrophotometric determination of copper and nickel exploiting differential kinetics and multivariate calibration

Sasaki, Milton Katsumi 09 June 2011 (has links)
Análise cinética diferencial explora diferenças em taxas reacionais entre os analitos e um sistema reacional comum; etapas de separação prévia dos analitos podem então ser prescindidas. Sistemas de análise por injeção em fluxo (FIA) se afiguram como uma ferramenta importante para métodos envolvendo essa estratégia, pois permitem um controle preciso da dispersão de reagentes / amostras e da temporização. O objetivo deste trabalho foi então explorar estes dois aspectos favoráveis visando a determinação simultânea de cobre e de níquel, a partir de suas reações com o reagente cromogênico 5-Br-PADAP. Três alíquotas de amostra eram simultaneamente inseridas, por meio de um injetor proporcional, no fluxo transportador reagente (5-Br-PADAP 75 mg L-1 + sistema tampão 0,5 mol L-1 em ácido acético / acetato, pH 4,7) de um sistema FIA em linha única. Durante o transporte em direção ao detector, as zonas estabelecidas se coalesciam, originando uma zona complexa que era monitorada a 562 nm. Os valores locais máximos e mínimos da função concentração / tempo obtida eram considerados para calibração multivariada utilizando a ferramenta quimiométrica PLS-2 (partial least squares - 2). A concentração do reagente, a capacidade tampão, a temperatura, a vazão, os comprimentos do percurso analítico e das alças de amostragem, bem como a distância inicial entre as zonas de amostra estabelecidas foram avaliados para construção dos modelos matemáticos. Estes foram criados a partir de 24 soluções-padrão mistas de Cu2+ e Ni2+ (0,00-1,60 mg L-1 em HNO3 a 0,1% v/v). Duas variáveis latentes foram suficientes para capturar > 98 % das variâncias inerentes ao conjunto de dados e erros médios das previsões (RMSEP) foram estimados em 0,025 e 0,071 mg L-1 para Cu e Ni, salientando a boa precisão do modelo de calibração. O sistema proposto apresenta boas figuras de mérito: fisicamente estável, quando mantido em operação por quatro horas ininterruptas, consumo de 314 \'mü\'g 5-Br-PADAP por amostra, frequência analítica de 33 amostras por hora (165 dados, 66 determinações) e erros nas leituras em sinais de absorbância tipicamente < 5%. Entretanto, verificou-se a inexatidão das previsões efetuadas pelo modelo proposto, quando comparadas aos resultados obtidos por ICP OES. A partir deste fato, tornam-se necessários maiores estudos referentes a este tipo de matriz, bem como de técnicas de mascaramento dos possíveis interferentes presentes / Differential kinetic analysis exploits the differences in reaction rates between the analytes and a common reactant system; prior steps of analyte separation can then be waived. Flow-injection systems (FIA) are considered as an important tool for methods involving such a strategy because they allow precise control of sample / reagent dispersion and timing. The aim of this work was then to exploit these two favorable aspects for the simultaneous determination of copper and nickel using the 5-Br-PADAP chromogenic reagent. Three sample aliquots were simultaneously inserted by means of a proportional injector into reagent carrier stream (75 mg L-1 5-Br-PADAP + 0.5 mol L-1 acetic acid / acetate, pH 4.7) of a single-line FIA system. During transport towards detection, the established zones coalesce themselves, resulting in a complex zone that was monitored at 562 nm. The local maximum and minimum values of the concentration / time obtained function were considered for multivariate calibration using the PLS-2 (partial least squares - 2) chemometric tool. The reagent concentration, buffering capacity, temperature, flow rate and lengths of the analytical path, sampling loops and initial distance between plugs were established and evaluated for the construction of mathematical models. To this end, 24 Cu2+ and Ni2+ (0.00 - 1.60 mg L-1, also 0.1% v/v HNO3) mixed standard solutions were used. Two latent variables were enough to capture > 98% of the variance inherent in the data set and average prediction errors (RMSEP) were estimated as 0.025 and 0.071 mg L-1 for Cu and Ni, emphasizing the good precision the calibration model. The proposed system presents good figures of merit: physical stability when kept in operation for four uninterrupted hours, consumption of 314 \'mü\'g 5-Br-PADAP per sample, sample throughput of 33 h-1 (165 data, 66 determinations) and error readings in absorbance signals typically <5%. However, inaccuracy of the predictions made by the proposed model when compared to results obtained by ICP OES was noted. Thus, further studies involving this type of matrix, as well as masking techniques of potential interferences present, are recommended
17

Projeto e desenvolvimento de um sistema de análises químicas por injeção em fluxo para determinações espectrofotométricas simultâneas de cobre e de níquel explorando cinética diferencial e calibração multivariada / Project and development of a flow-injection system for simultaneous spectrophotometric determination of copper and nickel exploiting differential kinetics and multivariate calibration

Milton Katsumi Sasaki 09 June 2011 (has links)
Análise cinética diferencial explora diferenças em taxas reacionais entre os analitos e um sistema reacional comum; etapas de separação prévia dos analitos podem então ser prescindidas. Sistemas de análise por injeção em fluxo (FIA) se afiguram como uma ferramenta importante para métodos envolvendo essa estratégia, pois permitem um controle preciso da dispersão de reagentes / amostras e da temporização. O objetivo deste trabalho foi então explorar estes dois aspectos favoráveis visando a determinação simultânea de cobre e de níquel, a partir de suas reações com o reagente cromogênico 5-Br-PADAP. Três alíquotas de amostra eram simultaneamente inseridas, por meio de um injetor proporcional, no fluxo transportador reagente (5-Br-PADAP 75 mg L-1 + sistema tampão 0,5 mol L-1 em ácido acético / acetato, pH 4,7) de um sistema FIA em linha única. Durante o transporte em direção ao detector, as zonas estabelecidas se coalesciam, originando uma zona complexa que era monitorada a 562 nm. Os valores locais máximos e mínimos da função concentração / tempo obtida eram considerados para calibração multivariada utilizando a ferramenta quimiométrica PLS-2 (partial least squares - 2). A concentração do reagente, a capacidade tampão, a temperatura, a vazão, os comprimentos do percurso analítico e das alças de amostragem, bem como a distância inicial entre as zonas de amostra estabelecidas foram avaliados para construção dos modelos matemáticos. Estes foram criados a partir de 24 soluções-padrão mistas de Cu2+ e Ni2+ (0,00-1,60 mg L-1 em HNO3 a 0,1% v/v). Duas variáveis latentes foram suficientes para capturar > 98 % das variâncias inerentes ao conjunto de dados e erros médios das previsões (RMSEP) foram estimados em 0,025 e 0,071 mg L-1 para Cu e Ni, salientando a boa precisão do modelo de calibração. O sistema proposto apresenta boas figuras de mérito: fisicamente estável, quando mantido em operação por quatro horas ininterruptas, consumo de 314 \'mü\'g 5-Br-PADAP por amostra, frequência analítica de 33 amostras por hora (165 dados, 66 determinações) e erros nas leituras em sinais de absorbância tipicamente < 5%. Entretanto, verificou-se a inexatidão das previsões efetuadas pelo modelo proposto, quando comparadas aos resultados obtidos por ICP OES. A partir deste fato, tornam-se necessários maiores estudos referentes a este tipo de matriz, bem como de técnicas de mascaramento dos possíveis interferentes presentes / Differential kinetic analysis exploits the differences in reaction rates between the analytes and a common reactant system; prior steps of analyte separation can then be waived. Flow-injection systems (FIA) are considered as an important tool for methods involving such a strategy because they allow precise control of sample / reagent dispersion and timing. The aim of this work was then to exploit these two favorable aspects for the simultaneous determination of copper and nickel using the 5-Br-PADAP chromogenic reagent. Three sample aliquots were simultaneously inserted by means of a proportional injector into reagent carrier stream (75 mg L-1 5-Br-PADAP + 0.5 mol L-1 acetic acid / acetate, pH 4.7) of a single-line FIA system. During transport towards detection, the established zones coalesce themselves, resulting in a complex zone that was monitored at 562 nm. The local maximum and minimum values of the concentration / time obtained function were considered for multivariate calibration using the PLS-2 (partial least squares - 2) chemometric tool. The reagent concentration, buffering capacity, temperature, flow rate and lengths of the analytical path, sampling loops and initial distance between plugs were established and evaluated for the construction of mathematical models. To this end, 24 Cu2+ and Ni2+ (0.00 - 1.60 mg L-1, also 0.1% v/v HNO3) mixed standard solutions were used. Two latent variables were enough to capture > 98% of the variance inherent in the data set and average prediction errors (RMSEP) were estimated as 0.025 and 0.071 mg L-1 for Cu and Ni, emphasizing the good precision the calibration model. The proposed system presents good figures of merit: physical stability when kept in operation for four uninterrupted hours, consumption of 314 \'mü\'g 5-Br-PADAP per sample, sample throughput of 33 h-1 (165 data, 66 determinations) and error readings in absorbance signals typically <5%. However, inaccuracy of the predictions made by the proposed model when compared to results obtained by ICP OES was noted. Thus, further studies involving this type of matrix, as well as masking techniques of potential interferences present, are recommended
18

Comparação entre analisadores com fluxo constante ou pulsado: aplicação a amostras de relevância farmacêutica, agronômica e/ou ambiental / Comparison of flow analyzers exploiting constant or pulsed flows: application to samples of pharmaceutical, agronomical and/or environmental relevance

Milton Katsumi Sasaki 24 November 2015 (has links)
Sistemas de análises químicas em fluxo com multi-impulsão empregam bombas solenoide como unidade propulsora de fluidos, as quais proporcionam fluxos pulsados. Estes provêm um eficiente transporte radial de massas, o que garante boa homogeneização das soluções envolvidas, mesmo em situações de dispersão limitada. O objetivo principal deste trabalho foi então comparar o desempenho de metodologias envolvendo reagentes imobilizados em sistemas de análises em fluxo com fluxos constantes ou pulsados. Para isto, foram selecionadas as determinações espectrofotométricas de ácido ascórbico em produtos farmacêuticos, utilizando reator tubular de polietileno (50 cm) com MnO2(s) imobilizado, e reação com formaldoxima (0,25 mol L-1); e de carbaril em águas naturais, explorando extração líquido-líquido com xileno imobilizado em membrana de PVDF, e solução de NaOH a 0,1 mol L-1 como fluxo aceptor. Adicionalmente, compararam-se os dois tipos de fluxo em uma nova titulação em fluxo, a titulação monitorada por traçador; a determinação de acidez total em vinagres foi selecionada e utilizaram-se as titulações por injeção em fluxo e programada em triângulo, ambas empregando solução de NaOH a 0,01 mol L-1 como titulante e fenolftaleína como indicador ácido-base, com monitoramento por traçador empregando azul brilhante FCF (ca. 6 mg L-1). Na determinação de ácido ascórbico, o desempenho do sistema com fluxos pulsados foi superior àquele com fluxos constantes quanto ao limite de detecção: 0,33 contra 0,60 mg L-1 (critério 3,3 ?), e à repetibilidade: d.p.r. estimado como 2,5 contra 5,6% (n = 20); quanto à exatidão, não foi encontrada diferença estatisticamente significativa entre o método proposto e o da Farmacopeia Britânica ao nível de confiança de 95%. Na determinação de carbaril, o uso de fluxos pulsados favoreceu a extração do analito, obtendo-se uma sensibilidade 9,3% maior relativamente ao emprego de fluxos constantes, além de uma melhor linearidade da curva analítica; entretanto, o método mostrou-se susceptível a interferência de outros metilcarbamatos, o que comprometeu sua aplicação à análise de águas naturais. Na determinação de acidez total, a exploração de fluxos pulsados proporcionou menores variações da razão dos valores de absorbância relativos ao monitoramento do traçador e do indicador; não foi encontrada diferença estatística entre as titulações em fluxo propostas e o método titulométrico de referência ao nível de confiança de 95% / Multi-pumping flow systems use solenoid pumps as fluid propelling devices, which deliver pulsed flows. These flows provide an efficient radial mass transport, thus good mixing conditions even in limited sample dispersion situations. The main objective of this work was then to compare the performance of methodologies involving immobilized reagents in flow systems with constant or pulsed flows. To this end, the spectrophotometric determinations of ascorbic acid in pharmaceutical products using a 50-cm polyethylene tubular reactor with immobilized MnO2(s) with further colour-forming reaction with 0.25 mol L-1 formaldoxime; and carbaryl in natural waters exploiting liquid-liquid extraction with xylene immobilized in a PVDF membrane and a 0.1 mol L-1 ¬¬NaOH solution as acceptor stream, were selected. Moreover, constant and pulsed flows were compared in relation to a novel strategy for flow titration, named tracer-monitored titration; the determination of total acidity in vinegars was selected and flow injection and triangle-programmed titrations were applied, both using a 0.01 mol L-1 NaOH solution as titrant, phenolphtalein as acid-base indicator and ca. 6 mg L-1 brilliant blue FCF as tracer. Regarding ascorbic acid determination, the pulsed flow system was superior in relation to the constant flow system for detection limit: 0.33 against 0.60 mg L-1 (3.3 ? criterion), and for repeatability: r.s.d. estimated as 2.5 against 5.6% (n = 20); in relation to accuracy, no significant differences between the proposed method and that of the British Pharmacopoeia were found at the 95% confidence level. Regarding carbaryl determination, use of pulsed flows favored the analyte extraction, leading to a 9.3% sensitivity improvement in relation to use of constant flows; besides the attainment of better linearity of the analytical curve. The method was however susceptible to interference of other methylcarbamates, thus the application to natural water analyses was impaired. Regarding total acidity determination, pulsed flows exploitation provided lower variations in the ratio of absorbance values related to the monitoring of tracer and indicator; no significant differences between the proposed titrations and the reference method were found at the 95% confidence level
19

Studium působení plazmatu na roztoky chininu / Study of plasma effects on quinine solutions

Procházková, Michaela January 2020 (has links)
This diploma thesis focuses on quinine solutions and quality of these solutions after applying plasma discharge. These electric discharges can be used to destroy some substances from the water. The theoretical part is focused on description of electric discharges in liquids and on the properties of quinine. In the experimental part, the properties of quinine solutions containing different electrolytes were analysed by UV-VIS spectrophotometer and fluorescence spectroscopy. Two different types of configurations of plasma discharges in liquids were used. Solutions were compared on the base of different concentration of quinine, different electrolytes, different configurations of plasma discharges and pH values of the solutions. Furthermore, the experimental work focuses on quinine solutions with the sodium nitrate. The time instability of the solutions was analysed. Also, the influence of the solution age and different types of the plasma discharge on the excitation and emission spectra of quinine were investigated.
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Mikrostanovení kobaltu metodami molekulové a atomové absorpční spektrometrie / Microdetermination of cobalt by methods of molecular and atomic absorption spectrometry

Charuza, Martin January 2012 (has links)
This diploma thesis is focused on microdetermination of cobalt by UV-VIS spectrophotometry with organic agents and comparison with atomic absorption spectrometry. In the first part properties, occurance and importance of cobalt in the environment are desribed, complete with as a part of vitamine B12. Attention is also given to cobalt compounds, especially in the oxidative states +II and +III. Methods of preconcentration and preparation cobalt determination in real samples are adduced. In this thesis are described some optical analytical methods with accept on spectrophotometric agents for determination of cobalt. The experimental part of this thesis icludes optimalization of the spectrophotometric determination of cobalt with choosen organic agents 4-(2-pyridylazo)resorcin and 2-(5-Brom-2-pyridylazo)-5-diethylaminophenol and optimalization of atomic absorption spectrometry for cobalt determination. All of real samples of water (surface, underground, mineral and waste) were measured by both 4-(2-pyridylazo)resorcin and 2-(5-Brom-2-pyridylazo)-5-diethylaminophenol via UV-VIS and via atomic absorption spectrometry. Results of determinations were compared. A sample of vitamine B12 was measured too by all techniques.

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