Conselho Nacional de Desenvolvimento Científico e Tecnológico / This work describes the development and application of analytical methods to establish parameters to the quality control of fruit and trunk latex of H. speciosa using High Performance Liquid Chromatography (HPLC) with diode array detect and evaporative light scattering detector (ELSD). As a first step chromatographic profile analytical method was developed and validated for the analysis of authentic sample of trunk latex of H. speciosa, and then the optimized method was used for the analysis of commercial samples of trunk latex sold in open markets from Sergipe, Brazil. The visual comparison of the chromatographic profiles of different samples of trunk latex allowed checking the authenticity and dissimilarities of chemical profiles of these samples. Seven chemical markers were purified by semi-preparative HPLC-DAD from the trunk latex of H. speciosa, the characterization by 1H, 13C NMR allowed the identification of the following substances cyclohexylethanoid glucoside cornoside, cyclohexylethanoid glucoside dihydrocornoside and (7,8)-treo-4,7,9,9 -tetrahydroxy-3,3 -dimethoxy-8-O-4 -neolignan-7-O-β-D-glucopyranoside. As a second step of our work chromatographic method for qualitative analysis of chemical markers lupeol, α-amyrin, β-amyrin e 3- β-O-acyl lupeol esters in the fruit latex of H. speciosa and in the mangaba commercial pulp was developed, the optimized method showed itself appropriate to the identification of such substances with adequate separation. In the end one analytical method for the quantification of the lupeol ester content in fruit latex and commercial pulp was developed and validated using the HPLC-DAD-ELSD. In the validation study were evaluated the figures of merit selectivity, linearity, limit of quantification and detection, precision, accuracy, stability and robustness according to the standards described in RE nº 899/03 (ANVISA). The quantification of lupeol ester by both detectors was significantly similar (259.44 μg/mg DAD and 269.58 μg/mg ELSD) with one coefficient of variation of 2.7%. This paper presents a contribution to the quality control of H. speciosa samples. / O presente trabalho apresenta o desenvolvimento e aplicação de métodos analíticos para o controle de qualidade do látex do fruto e do caule de H. speciosa Gomes utilizando cromatografia líquida de alta eficiência com os detectores de arranjo de diodos e evaporativo por espalhamento de luz (HPLC-DAD-ELSD). No primeiro momento, um método analítico para a obtenção do perfil cromatográfico foi desenvolvido e validado para a análise de uma amostra autêntica do látex do caule de H. speciosa; em seguida foi utilizado o método otimizado para a análise de amostras do látex do caule comercializadas em feiras livres do Estado de Sergipe. A comparação visual dos perfis cromatográficos das diferentes amostras do látex do caule permitiu averiguar a autenticidade e as dissimilaridades dos perfis químicos dessas amostras. Utilizando uma coluna semi-preparativa, sete marcadores químicos foram purificados a partir do látex do caule de H. speciosa; a caracterização por RMN 1H, 13C possibilitou a identificação das seguintes substâncias: ciclohexiletanóide glicosilado cornosídeo, ciclohexiletanóide glicosilado dihidrocornosídeo e (7,8)-treo-4,7,9,9 -tetrahidroxi-3,3 -dimetoxi- 8-O-4 -neolignana-7-O-β-D-glicopiranosídeo. No segundo momento, um método cromatográfico para análise qualitativa dos marcadores químicos lupeol, α-amirina, β-amirina e ésteres 3- β-O-acil lupeol no látex dos frutos de H. speciosa e em polpa comercial de mangaba foi desenvolvido. Por fim, um método analítico para a quantificação do teor de ésteres de lupeol em látex dos frutos de H. speciosa e em polpa comercial foi desenvolvido e validado utilizando HPLC-DAD-ELSD. No estudo da validação foram avaliadas as figuras de mérito seletividade, linearidade, limite de quantificação e detecção, precisão, exatidão, estabilidade e robustez conforme as normas descritas na RE nº 899/03 (ANVISA). A quantificação do teor de ésteres de lupeol por ambos os detectores se mostraram significativamente similares (259,44 μg/mg para o DAD e 269,58 μg/mg para o ELSD) com coeficiente de variação de 2,7 %. Este trabalho apresenta uma contribuição ao controle de qualidade de amostras de H. speciosa.

Made available in DSpace on 2014-07-29T15:11:10Z (GMT). No. of bitstreams: 1 Tese Rodrigo I Medeiros.pdf: 2094204 bytes, checksum: 5d1ccae92a1ff1a8355428a531e6a4b9 (MD5) Previous issue date: 2011-03-18 / An analytical chemical method for the forensic analysis of an illicit drug merla, whose the main constituent is the cocaine was development. Thermogravimetric analysis admitted to understand the thermal behavior of samples and quantifying the stages of mass loss, which together with the quantification endothermic event in DSC, the results were essential for the generation of analytical answers used to construct the data matrix of the statistical analysis. An efficient process for the precipitation of inorganic substances was established, which simultaneously allowed the extraction of two liquid fractions, organic and aqueous, being determinate a partition coefficient of 96,22 % for cocaine, using ethyl acetate as solvent, which showed lower elution time (0.58 min.) among the solvents evaluated. A method by Fast GC for cocaine analysis was developed, reducing the analysis time of 14.5 to 4.5 min was developed, which allowed analyze merla sample and the normalization of the chromatographic peaks of cocaine, demonstrated the great variation of its concentration in merla. Noticed of the potential of the method involving the thermo-analytical and chromatographys techniques to generate experimental results obtained statistically enabled a classification and grouping of samples by Euclidean Distance by the Hierarchical Cluster Analysis (HCA), estimated whether seized samples with different users were manipulated in the same laboratory and if determined city has separate laboratories for illegal preparatiom of drug narcotic. / Neste estudo realizou-se o desenvolvimento de um método químico analítico forense para a análise de uma droga ilícita a base de cocaína, a merla. As análises termogravimétricas permitiram conhecer o comportamento térmico das amostras e quantificar as etapas de perdas de massa, que juntamente com a quantificação de evento endotérmico em DSC, foram essenciais para a geração de resultados analíticos utilizados na construção da matriz de dados do tratamento estatístico. Foi estabelecido um processo eficiente para a precipitação das substâncias inorgânicas, que simultaneamente permitiu a extração de duas frações líquidas, orgânica e aquosa, sendo determinado um coeficiente de partição de 96,22 % para a cocaína, tendo como solvente acetato de etila, o qual apresentou menor tempo de eluição (0,58 min.) dentre os solventes avaliados. Foi desenvolvido um método Fast GC para análise de cocaína, diminuindo o tempo de análise de 14,5 min para cerca de 4,5 min, o qual permitiu analisar as amostras de merla e, pela normalização dos picos cromatográficos da cocaína, perceber a grande variação de sua concentração na merla. Observou-se o potencial do método envolvendo as técnicas termoanalíticas e cromatográficas para geração de resultados experimentais que tratados estatisticamente possibilitaram a classificação e o agrupamento das amostras pela distância euclidiana obtida por Análise Hierárquica de Agrupamentos (HCA), avaliando se amostras apreendidas com diferentes usuários foram manipuladas em um mesmo laboratório e se determinada cidade possui laboratórios distintos de preparo ilegal de tóxico-entorpecente.

Une des évolutions dans le domaine de l'analyse chimique concerne la miniaturisation des systèmes d'analyse. Cette tendance s'accompagne du développement de nouvelles approches expérimentales basées, par exemple, sur l'intégration de plusieurs étapes analytiques, couplées en ligne en système miniaturisé. Cette intégration, en ligne, d'étapes mettant en jeu des mécanismes de séparation différents et généralement orthogonaux, implique cependant d'être capable de définir des zones (segments de colonne vides et/ou remplis de phase stationnaire) présentant des chimies de surface adaptées. L'approche choisie pour la préparation de ces colonnes " multimodales ", repose sur (1) la synthèse d'un monolithe de silice poreux "générique " dans des tubes capillaires de quelques dizaines de microns de diamètre interne et (2) la modification de surface localisée dans le capillaire permettant d'apporter des propriétés de surface complémentaires. Dans le cadre de cette thèse, deux procédés de fonctionnalisation innovants, initiés par photochimie, ont été développés pour la préparation des colonnes multimodales miniaturisées : la photopolymérisation, basée sur des réactions de polymérisation radicalaire, et la " photoclick chemistry ", basée sur un greffage radicalaire contrôlé (et non plus une polymérisation). Un état de l'art de leur utilisation en sciences séparatives a été dressé pour chacun des procédés, afin de guider le choix des stratégies de greffage. Après une optimisation des conditions de greffage, les résultats présentés dans ce manuscrit montrent que ces procédés de fonctionnalisation sont rapides (fonctionnalisation en quelques minutes), efficaces, polyvalents (transposables à de multiples greffons) et localisables. Leurs potentiels respectifs dans la préparation des colonnes multimodales ont ensuite été démontrés pour la préconcentration/séparation en ligne de plusieurs composés. L'approche par " click chemistry " qui permet un meilleur contrôle du greffage, a été étendue au greffage de biomolécules pour la préparation de supports d'immunoaffinité. Ainsi, une colonne multimodale composée d'une première zone remplie de monolithe photogreffée avec des aptamères et une deuxième zone vide a été préparée pour la préconcentration/séparation électrocinétique en ligne de l'Ochratoxine A / Miniaturization of analytical processes is a general trend in analytical chemistry. Such trend is driven by the development of new experimental approaches based, for example, on hyphenated analytical steps or techniques. The in-line coupling of different and generally orthogonal/complementary separation mechanisms at the microscale, is dependent on the capability to define functional segments (open column segments and/or filled with stationary phase). Preparation of such "multimodal" capillary columns is based on (1) the in-capillary synthesis of a "generic" porous silica monolith and (2) on its localized chemical surface modification to define specific functional segments. Herein, two innovative photo-functionalization processes have been investigated for the preparation of multimodal miniaturized columns. The former, called photopolymerization is based on acrylate free radical polymerization reactions while the latter, called photografting, implements the thiol-ene "photoclick chemistry" reaction. These photo-initiated processes, after optimization, prove to be rapid (within few minutes), versatile (adapted to the grafting of various monomers) and localizable. Photopolymerization of acrylate monomers on activated silica monolith (using ?-methacryloxypropyltrimethoxysilane) gives rise to highly retentive columns due to the polymeric nature of the layer obtained. Photografting of octadecanethiol on vinylized silica columns leads to monolayer-like coating. The preparation of dedicated multimodal columns using such approaches was then successfully applied to the in-line preconcentration / separation of neuropeptides and preconcentration / fractionation of various neutral and charged compounds. The "click chemistry" approach which allows a better control of the reaction, has been extended to the grafting of biomolecules for the preparation of immunoaffinity supports. Thus, a multimodal column composed a 1-cm length aptamer-functionalized monolith at the entrance of a CZE open capillary has been prepared and successfully applied to the in-line preconcentration/electrokinetic separation of Ochratoxin A in white wine and beer

La chromatographie à lit mobile simulé (procédé SMB) est une technique de séparation bien maîtrisée dans certains secteurs traditionnels tels que la séparation de sucres et d’hydrocarbures. Cependant, son application à la séparation de composés à haute valeur ajoutée dans l’industrie pharmaceutique pose de nouveaux problèmes liés à la nature des produits à séparer ainsi qu'aux exigences plus strictes en matière de pureté et de quantités produites. Les principaux problèmes ouverts sont notamment la détermination des conditions de fonctionnement optimales, la conception de structures robustes de régulation, et le développement d’un système de supervision permettant la détection et la localisation de dégradations de fonctionnement. Ces tâches requièrent l’usage d’un modèle mathématique du procédé ainsi qu’une méthodologie d’estimation paramétrique. L’étude et le développement des modèles mathématiques pour ce type d’installation ainsi que l’estimation des paramètres des modèles sur base de mesures expérimentales constituent précisément l’objet de nos travaux de doctorat.<p><p>Les modèles mathématiques décrivant les procédés SMB consistent en les bilans massiques des composés à séparer. Ce sont des modèles à paramètres distribués (décrit par des équations aux dérivées partielles). Certains ont un comportement dynamique de type hybride (c'est-à-dire faisant intervenir des dynamiques à temps continu et des événements discrets). Quelques modèles ont été développés dans la littérature. Il s’agit de sélectionner ceux qui paraissent les plus intéressants au niveau de leur temps de calcul, de leur efficacité et du nombre de paramètres à déterminer. En outre, de nouvelles structures de modèles sont également proposées afin d’améliorer le compromis précision / temps de calcul. <p><p>Ces modèles comportent généralement certains paramètres inconnus. Ils consistent soit, en des grandeurs physiques mal définies au départ des données de base, soit, en des paramètres fictifs, introduits à la suite d'hypothèses simplificatrices et englobant à eux seuls un ensemble de phénomènes. Il s’agit de mettre au point une procédure systématique d’estimation de ces paramètres requérant le moins d’expériences possible et un faible temps de calcul. La valeur des paramètres est estimée, au départ de mesures réelles, à l'aide d'une procédure de minimisation d'une fonction de coût qui indique l’écart entre les grandeurs estimées par le modèle et les mesures. La sensibilité du modèle aux écarts sur les paramètres, ainsi que l’identifiabilité du modèle (possibilité de déterminer de manière univoque les paramètres du modèle) sur la base de mesures en fonctionnement normal sont étudiées. Ceci fournit un critère de comparaison supplémentaire entre les différents modèles et permet en outre de déterminer les conditions expérimentales optimales (choix du type d’expérience, choix des signaux d’entrée, choix du nombre et de la position des points de mesures…) dans lesquelles les mesures utilisées lors de l’estimation paramétrique doivent être relevées. De plus, les erreurs d’estimation sur les paramètres et les erreurs de simulation sont estimées. La procédure choisie est ensuite validée sur des données expérimentales recueillies sur un procédé pilote existant au Max-Planck-Institut für Dynamik komplexer technischer systeme (Magdebourg, Allemagne).<p> / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

Erythromycin (ERY) is a macrolide antibiotic which is used in the treatment of acne vulgaris.Acne is a common skin condition that occurs when the sebaceous glands and hair shafts become infected by the bacteria Propionibacterium acnes. Acne is a chronic condition that may last for years and the severity of the effects of the disease on patients is often undermined especially in third world countries where more emphasis is placed on other more life-threatening diseases. It may cause considerable physical and emotional distress to sufferers along with the possibility of permanent scarring. Although use of topical ERY formulations is not the first line of treatment it has proven to be effective in treating inflammation of skin and skin structures cause by the responsible bacteria. To-date there are a variety of vehicles which are used in preparing topical ERY formulations namely ointment and gel bases, alcoholic solutions and pledgets. All the gel formulations on the market contain hydroxypropyl cellulose, alcohol and water along with the active ingredient(s). However, some gel formulations contain propylene glycol in addition to these excipients an example being Emgel®. Propylene glycol has been shown to affect the penetration of topically applied drugs through the skin suggesting that it would be highly likely that those formulations which contain propylene glycol may release more ERY into the skin following application. With this in mind, two ERY gel formulations were produced which contained different percentages of propylene glycol. According to the FDA guidelines, pharmacokinetic measurements in blood, plasma and/or urine of topical dermatological drug products are not feasible to document bioequivalence since the active ingredient(s) in topical formulations is/are not intended to be absorbed into the systemic circulation and in addition, concentrations in extracutaneous biological tissues would generally not be measurable. This limits determination of bioavailability and assessment of bioequivalence of such products to pharmacodynamic measurements, clinical trials and dermatopharmacokinetic (DPK) measurements such as tape stripping (TS) and microdialysis (MD).TS is a sampling technique which involves sequential removal of layers of the stratum corneum using strips of adhesive tape. This technique has found increasing use in DPK studies for investigation of drug kinetics in the skin following the application of a topical formulation. The technique has also been used as a diagnostic tool in assessing the quality of the stratum corneum in diseased skin. In the current research study, the tape stripping technique was used to investigate the pharmaceutical/biological availability of topical gel formulations containing ERY. MD is another DPK sampling technique which has been used to determine the amount of a topically applied drug that penetrates through the stratum corneum to reach deeper tissues of the skin. The in vivo sampling technique involves the insertion of microdialysis probes beneath the skin surface in the dermal tissue and allows for real-time sampling of the analyte at its target site. Recently in vitro MD has also been successfully used to assess the pharmaceutical availability of a topical corticosteroid, mometesone furoate, from topical formulations. Based on this work, microdialysis was used to determine the pharmaceutical availability of ERY from gel formulations which were developed for use in this research. The results of the pharmaceutical availability of ERY from in vivo tape stripping studies and the in vitro microdialysis studies were compared to establish correlation between the data. Pharmaceutical equivalence and bioequivalence data obtained from the respective studies on the gel formulations were investigated by statistical analysis of the data generated from both the in vitro and in vivo experiments. In summary the objectives of this research were: 1. To develop and validate a high performance liquid chromatography method suitable to analyse ERY concentrations obtained from in vitro microdialysis studies and in vivo tape stripping studies. 2. To prepare two different ERY gel formulations with different percentage content of propylene glycol. 3. To determine the pharmaceutical availability of ERY from two different gel formulations using in vitro microdialysis. 4. To develop and validate a tape stripping technique which could be used to determine percutaneous penetration and bioequivalence of the gel formulations. 5. To compare in vitro microdialysis and in vivo tape stripping data and attempt to establish a correlation between the two different approaches.

La chromatographie à contre courant (CCC) est une technique de purification chimique préparative quitravaille avec un système biphasique liquide. Une phase est la phase mobile, l'autre phase est la phasestationnaire. Il n'y a aucun support solide: un champ de force centrifuge est utilisé pour maintenir en place laphase stationnaire. Ce travail est une contribution à l'étude de la purification préparative par CCC. Après uneimportante étude bibliographique des procédés de purification en continu tant en CCC qu'autres, il est montréque la méthode dite "multi-dual-mode", ou MDM, est une solution possible. Elle consiste à utiliser le fait queles deux phases liquides peuvent servir de phase stationnaire: il suffit d'inverser le sens de circulation et lanature de la phase mobile (méthode dual-mode). Le mélange est séparé de façon classique pendant untemps chronométré, puis on inverse le rôle des phases: la phase mobile devient stationnaire et vice versa eton inverse également le sens de circulation (ascendant devient descendant ou vice versa). On sort lescomposants du mélange soit d'un coté de la colonne CCC, soit de l'autre. La méthode est mise en oeuvrepour purifier le Bleu de Coomassie en le débarassant des ses composés polaires (d'un coté) et apolaire (del'autre coté de la colonne et en accumulant dans la colonne la fraction de polarité intermédiaire, fractiond'intérêt. Une nouvelle colonne hydrostatique de petit volume (30 mL) a également été testée: elle permetde tester un nouveau système liquide très rapidement. / Counter-current chromatography (CCC) is a preparative purification technique that works with the twoliquid phases of a biphasic liquid system. One phase is used as the mobile phase when the other phase isused as the stationary phase. There is no solid support: centrifugal fields are used to obtain a support-freeliquid stationary phase. This work contains an exhaustive bibliographic study of what can be found in theliterature concerning continuous chromatographic processes. The multi-dual-mode (MDM) process was foundto be the best one able to purify large amount of crude mixtures. The MDM method starts with a classicalseparation of the mixture followed by a switch of both the liquid phase nature and the flowing direction. Themobile phase flowing e.g. in a descending direction becomes the stationary phase. The previous stationaryphase becomes the mobile phase flowing in the ascending direction (or vice versa). The purified compoundsof the introduced mixture are eluted at one side of the column or the other according to their polarity. TheMDM method was used to purify a crude sample of Coomassie Blue: the polar part of the dye was eluted atthe column top (or head) and the apolar part at the column bottom (or tail) while the essential part of the dyewas trapped inside the CCC column. The work also presents a new small volume (30 mL) hydrostatic CCCcolumn. It is shown that this column could be used to test quickly the potential of a given biphasic liquidsystem.

The coconut (Cocos nucifera L) is a rich source of nutrient and as well as other plants is under attack from different types of pests and diseases, causing losses to producers. Pesticide use remains the primary control strategy and combat pests and diseases in agricultural crops. However, the excessive and indiscriminate use of these products can cause serious harm to human health and the environment due to the high toxicity these products. In Brazil, until now no stipulated values of maximum residue limits (MRLs) for pesticides in coconut crops. Similarly, there is little information about the degree of contamination. Therefore analytical methodologies must be developed for the determination of pesticide residues in coconut cultivation, aiming to ensure human health. Thus, this work proposes a methodology to determine residue of bromopropylate, clofentezine, coumaphos, difenoxuron, diniconazole, fenvalerate, flumetralin, flumeturon, teflubenzuron in greens stipe, appling the matrix solid phase dispersion (MSPD) and liquid chromatography with diode array detector (LC-DAD) for analysis. In this study we evaluated the best sorbent/solvent combinations (using silica, Florisil, neutral alumina, C18 and coordination polymers [Zn(BDC)(H2O)2]n, [Zn(BDC)0.99(NH2-BDC)0.01)(H2O)2]n, [Zn(BDC)0.95(NH2-BDC)0.05)(H2O)2]n, [Zn(BDC)0.90(NH2-BDC)0.10)(H2O)2]n/acetonitrile), the best ratio of sample/ adsorbent mass, as volume of the elution solvent used for extraction were evaluated. Among the investigated combinations, the system comprising 0.25 g of stem, 1 g of neutral alumina and 5 mL of acetonitrile was the most efficient in recovery resulting from 70 and 93%, with relative standard between 1.6% and 10%, in the levels of concentration 0.04, 0.08, 0.2, 0.4, 2.0, 3.0; 4.0 ìg g-1. The linearity was above 0.9991 and the limits of detection between 0.01 and 0.05 ìg g-1 and quantification 0.05 and 0.2 ìg g-1. Among the polymeric phases, the [Zn(NH2BDC)0.1(BDC)0.9(H2O)2]n was most eficiente in the extraction of bromopropylate, clofentezine, coumaphos, difenoxuron, diniconazole, fenvalerate, flumetralin, flumeturon and teflubenzuron. / O coqueiro (Cocos nucifera L.) e uma rica fonte de nutrientes e, assim como outras plantas e alvo de ataque de diferentes tipos de pragas e doencas, causando prejuizos aos produtores. O uso de pesticidas continua sendo a principal estrategia de controle e combate de pragas e doencas nas plantacoes agricolas. No entanto, o uso excessivo e indiscriminado desses produtos podem ocasionar serios danos a saude humana e ao ambiente, devido a elevada toxicidade desses produtos. No Brasil, ate o momento, nao ha valores estipulados de limites maximos de residuos (LMR) para pesticidas na cocoicultura. Do mesmo modo, ha pouca informacao quanto ao grau de contaminacao. Portanto metodologias analiticas tem de ser desenvolvidas para determinacao de residuos de pesticidas na cultura de coqueiro, com intuito de assegura essencialmente a saude humana. Nesse sentido, esse trabalho propoe uma metodologia que determine residuo de bromopropilato, clofentezina, cumafos, difenoxurom, diniconazol, fenvalerato, flumetralina, flumeturom, teflubenzurom em estipe de coqueiro, fazendo uso da tecnica de DMFS para extracao e CL-DAD para analise. Nesse estudo foram avaliados as melhores combinacoes sorvente/solvente (utilizando silica gel, Florisil, alumina neutra, C18, e polimeros de coordenacao [Zn(BDC)(H2O)2]n, [Zn(BDC)0,99(NH2-BDC)0,01)(H2O)2]n, [Zn(BDC)0,95(NH2-BDC)0,05)(H2O)2]n, [Zn(BDC)0,90(NH2-BDC)0,10)(H2O)2]n/acetonitrila). Avaliou-se a melhor relacao de massa amostra/adsorvente, alem do volume do solvente de eluicao utilizado para extracao. Dentre as combinacoes avaliadas, o sistema constituido de 0,25 g de estipe, 1 g de alumina neutra e 5 mL de acetonitrila foi o mais eficiente resultando em recuperacao entre 70 e 93% com precisao entre 1,6% e 10% nos niveis de concentracao 0,04, 0,08, 0,2, 0,4, 2,0, 3,0; 4,0 Êg g-1. As linearidades foram acima de 0,9991 e os limites de deteccao foram entre 0,01 e 0,05 Êg g-1 e de quantificacao entre 0,05 e 0,2 Êg g-1. Entre as fases polimericas estudadas, o [Zn(NH2BDC)0,1(BDC)0,9(H2O)2]n foi o mais eficiente na recuperacao de bromopropilato, clofentezina, cumafos, difenoxurom, diniconazol, fenvalerato, flumetralina, flumeturom e teflubenzurom.

The goal of this project is to use the Generic Tutorial System for the Sciences (GTSS) tools to develop a prototype interactive chromatography simulation with the Chrom-Quiz system. This will demonstrate Chrom-Quiz/chromatography integration as a teaching system.

(EN) This dissertation thesis is focused on physicochemical and chromatographic characterization of polyaniline-coated stationary phases. In the first part, surfaces of bare silica and octadecyl silica sorbents were modified by in-situ chemical polymerization of aniline hydrochloride and their subsequent systematic characterization was performed by using the linear solvation energy relationship approach in the HILIC mode of capillary LC. In addition, several common physicochemical techniques were used to characterize properties of these altered materials. The modified sorbents were then packed into capillary columns. The retention interactions taking place between solute and the separation system were evaluated on the basis of retention data of a number of various solutes. The results showed that polyaniline coating had a significant effect on the retention promoting interactions of both polyaniline-coated stationary phases. The assumed mixed-mode retention mechanism was proven for both the stationary phases. The second part dealt with investigation of the separation potential of polyaniline- coated silica stationary phase in different chromatographic modes. The retention factor curves of structurally similar solutes were constructed as a function of organic modifier portion in the mobile phase....

This thesis aims to find out the effective diffusivity (Deff) of a porous material – γ-alumina, using an unsteady state method with two inert gases at ambient condition with no reactions. For porous materials, Deff is important because it determines the amount of reactants that transfers to the surface of pores. When Deff is known, the apparent tortuosity factor of γ-alumina is calculated using the parallel pore model. The apparent tortuosity factor is important because: (a) it can be used to back-calculate Deff at reacting conditions; (b) once Deff with reactions is known, the Thiele modulus can be calculated and hence the global reaction rate can be found; (c) apparent tortuosity factor is also important for modelling purposes (e.g. modelling a packed-bed column or a catalytic combustion reactor packed with porous γ-alumina in various shapes and monoliths). Experimental measurements were performed to determine the effective diffusivity of a binary pair of non-reacting gases (He in N2, and N2 in He) in spherical γ-alumina pellets (1 mm diameter), and in γ-alumina washcoated monoliths (washcoat thickness 20 to 60 µm, on 400 cpsi (cells per square inch) cordierite support). The method used is based on the chromatographic technique, where a gas flows through a tube, which is packed with the sample to be tested. A pulse of tracer gas is injected (e.g. using sample loops: 0.1, 0.2, 0.5 ml) and by using an on-line mass spectrometer the response in the outlet of the packed bed is monitored over time. For the spherical pellets, the tube i.d. = 13.8 mm and the packed bed depths were 200 and 400 mm. For monoliths the tube i.d. = 7 mm and the packed lengths were 500 and 1000 mm. When the chromatographic technique was applied to the monoliths, it was observed that experimental errors can be significant, and it is very difficult to interpret the data. However, the technique worked well with the spherical pellets, and the effective diffusivity of He in N2 was 0.75 – 1.38 × 10-7 m2 s-1, and for N2 in He was 1.81 – 3.10 × 10-7 m2 s-1. Using the parallel pore model to back-calculate the apparent tortuosity factor, then a value between 5 to 9.5 was found for the pellets.