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The theoretical and practical aspects of the sensitivity that can be achieved in a flow injection manifold with on-line chemical reactions are investigated with a view to decreasing the detection limits. Optimization of the common manifold configurations, normal single line, double line and reverse single line, was carried out by varying the parameters of flow rate(s), injected volume, reagent concentration and manifold length. The reaction of iron(II) with 1,10-phenanthroline was used for the comparison. Ascorbic acid was added to both sample and reagent to avoid side reactions of 1,10-phenanthroline and iron(III). Results showed that manifold and confluence point geometry affected peak height. A sensitivity comparison, using a 21 point calibration, showed that the manifold sensitivity is similar but that the reverse single line $>$ double line $>$ normal single line. The double line manifold has the best detection limit (10 ng mL$\sp{-1})$ due to the absence of a refractive index effect. Experiments were performed to look at the use of solid molybdate reagent columns for the determination of phosphate. Solid columns without any support were found to be very unstable. Stability was improved by the addition of 5 $\mu$m silica but it was still not reproducible enough. Precipitation of barium molybdate within a cation exchange resin did produce better reproducibility but the complexity added made it impractical. Membrane reagent introduction for the determination of phosphate and chloride was investigated. Nafion cation exchange tubing was used for the introduction of acid and hydrazinium ion for phosphate, and acid, iron(III) and thiocyanate and mercury(II) for chloride. Molybdate was introduced for phosphate determination using a supported liquid membrane of tri-butyl phosphate in n-heptane. Sensitivity was improved for the phosphate determination but not for the chloride determination. The use of an ammonia permeation tube was studied for calibration in flow injection. Nessler's reagent was used for the determination. Release rate temperature variation and day to day reproducibility were investigated. Analysis of a sample of pond water was achieved using the permeation tube for on-line, zero dilution, standard additions calibration.

Data processing tools are valuable to the analytical chemist as they can speed up the analysis, and sometimes solve problems that are not feasible to solve in a traditional manner. However, the complexity of many data processing tools can make their use daunting for the inexperienced user. This thesis includes two applications and two tools for data processing. The first application focuses on minimizing the manual input, reducing the time required for a simple task. The second application required more manual input, in the form of parameter selection, but process far more data.  The data processing tools both include features that simplify the manual work required. The first by including visual diagnostics tools that helps in setting the parameters. The second via internal validation that makes the tool’s process more robust and reliable, and thereby less sensitive to small changes in the parameters. No matter how good or precise a data processing tool is, if it is so cumbersome that it is not used by the analytical chemists that need it, it is useless. Therefore, the main focus of this thesis is to make data processing easier. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Submitted.</p>

voir pdf pp. 182-4

Grâce à la microfluidique, la stabilité et les propriétés de deux types d'émulsions ont pu être sondées. Il s'agit d' émulsions non adhésives et d'émulsions adhésives. Les points importants des différentes thématiques abordées sont résumés dans les paragraphes suivants. – La déstabilisation hydrodynamique d'une émulsion : La fusion de gouttes proches est favorisée par leur séparation. En réalité les gouttes sont localement rapprochées car une dépression se crée lors de leur éloignement. Cela les oblige à former localement des bourgeons qui les rendent plus proches. – La déstabilisation d'une émulsion par un champ électrique : L'état de coalescence temporaire a été mis en évidence. Un diagramme de coalescence de paires a été établi. Pour des trains de gouttes, le diagramme de stabilité coïncide avec celui de paires. La seule différence est observée pour des temps d'excitation plus courts que le temps de relaxation des charges. Dans ce cas, la "coalescence partielle" est remplacée par une simple coalescence. – La caractérisation d'émulsions inverses adhésives : La technique pour former une émulsion inverse très adhésive, c'est de la former très peu adhésive et d'évaporer le bon solvant. Les bicouches artificielles formées avec ces émulsions miment presque toutes les propriétés des membranes biologique. Suivant la quantité de mauvais solvant, elles peuvent se présenter sous forme gaz, fluide ou gel. – La perméabilité des bicouches artificielles : Avec un choc osmotique, la perméabilité à l'eau de ces bicouches a été mis en évidence. Elles sont faiblement perméables aux ions. Avec un champ électrique, leur perméabilité aux ions est possible grâce à la formation de pores à travers elles. Un diagramme d'électroporation s'en est suivi. Pour les deux moteurs de perméabilité, le constat principal est la variation notable de la perméabilité instantanée lors d'une transition de phase dans les bicouches. Ces résultats sont très intéressants et montrent à quel point les émulsions en générale regorge encore de secrets. Pour les émulsions adhésives, les comportements que nous avons observés sur les trains de gouttes sont déjà très surprenants. Nous pouvons nous attendre à des comportements encore plus surprenants dans le cas d'émulsions macroscopiques. En outre, ces effets sont généralement "contre-intuitifs" : la déstabilisation d'une émulsion dense est facilitée par sa décompression ! la séparation des phases huileuses et aqueuses d'une émulsion de pétrole est optimale pour une application d'un champ électrique pas très élevé (un champ électrique élevé entraîne la "coalescence partielle" des gouttes)... Tous ces comportements "contre intuitifs" peuvent être très utiles pour des applications futures dans le domaine des matériaux. En ce qui concerne les émulsions adhésives, les résultats établis ici sont très prometteurs. Elles permettent de mimer les membranes biologiques. Grâce à la perméabilité des membranes artificielles formées, nous pouvons imaginer des gouttes, très concentrées en ions, qui seraient des pompes à solvant : elle permettraient, par exemple, de changer des concentrations de microréacteurs... En ce qui concerne l'électroporation, les expériences peuvent encore être peaufinées. La prochaine étape sera certainement de contrôler directement le potentiel des gouttes, par des pointes par exemple. Cela éviterait, en effet, leur séparation. Dans ce cas, il est clair que le mécanisme d'électroporation pourrait avoir une réelle valeur ajoutée car les réservoirs seront figés et des échanges pourraient se faire. On pourrait espérer ainsi réaliser des expériences d'insertion de molécules dans des gouttes, par électroporation, comme cela existe actuellement pour des vésicules.

Le pesticide organophosphoré azinphos-méthyle (AZM) voit son efficacité de photodégradation augmenter avec l'énergie d'excitation, vraisemblablement dû à des différences de réactivité entre états excités. Sa dégradation sous excitation directe conduit à la formation de benzotrione qui se dégrade en l'acide anthranilique. Un autre organophosphoré, le cyanophos, se dégrade sous excitation directe en faisant intervenir les états excités triplet et singulet pour former : le 4-cyanophénol, le cyanophos-oxon et un dérivé de l'acide benzoïque. Le dépot de l'AZM dans l'argile conduit à une meilleur absorption de la lumière solaire. Sa photodégradation sur argiles et oxyde de fer est efficace, avec une vitesse dépendant essentiellement de la nature et de l'épaisseur du solide du taux d'humidité et de fer(III). L'AZM se dégrade par des processus issus d'une excitation directe et d'autres photoinduits par le support. La formation de radicaux hydroxyles a également été mise en évidence

Kinetic studies of the cobalt (II)-4, 4’, 4’’, 4’’’-tetrasulfophtalocyanine and cyanide system were performed under argon and in air over temperature ranges of 294-314°K and 294-324°K, respectively. Two reactions were detected under argon. One was quite rapid and was followed on the stopped-flow apparatus. The results are consistent with the perturbation of a monomer-dimer equilibrium. The second reaction was slow enough to be followed spectrophotometrically on the Cary Model 14 spectrophotometer. The second order rate constant of 0.11 M-1 sec-1 at 294°K has been attributed to the rate of substitution of the second cyanide addition to a dye-cyanide complex. Activation parameters, ΔH* and ΔS* were obtained over a temperature range of 294-314°K yielding values of 3 +/- 0.3 kcal/mol and -56 +/- 5 e.u., respectively. Reexamination of this system in air revealed three reactions. The first reaction was rapid and measurable on the stopped-flow apparatus. This reaction has been interpreted as a perturbation of the monomer-dimer equilibrium. The other reactions were monitored o the Cary Model 14 spectrophotometer and produced a biphasic curve. The slower reaction yields a rate constant, ks of 3.4 +/- 0.15 x 10-3 s-1 at 294°K and is in agreement with the value reported for the dissociation of the dimer when corrections are made for differences in ionic strength. The activation parameters ΔH* and ΔS* for the slow step were calculated to be 9.1 +/- 0.9 kcal/mole and -39 +/- 3 e.u., respectively, over a temperature range of 294-324K. We have no good explanation for the faster step, kf. However, a linear plot of 1n (dye concentration) vs. time shows kf is a first order rate constant with a value of 2.0 +/- 0.15 x 0.10-2 s-1 at 294°K. There was no dependency of kf on oxygen concentration, thus oxidation involving molecular oxygen is excluded as a possible step Moreover, there is no simple relationship between kf and cyanide concentration. Activation parameters, ΔH*f and ΔS*f of 7.6 +/- 0.5 kcal/mole and -40 +/-4 e.u., respectively, were obtained over a temperature range of 294-324°K.

The focus of this study is the potential use of FTIR imaging as a tool for objective automated histopathology. The Thesis also reports the use of multivariate statistical techniques to analyse the FTIR imaging data. These include Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA), Multivariate Curve Resolution (MCR) and Fuzzy C-Means Clustering (FCM). The development of a new PCA-FCM Clustering hybrid that can automatically detect the optimum clustering structure is also reported. Chapter 1 provides a brief introduction to the use of vibrational spectroscopy to characterise biomolecules in tissues and cells for medical diagnosis. Chapter 2 details the basic histology of a lymph node before proceeding to present imaging results gained from the analysis of both healthy and diseased lymph node tissue sections. The ability of each multivariate technique to discriminate different tissue types is discussed. In addition, the spectral features that are characteristic for each tissue type are reported. The development and application of a new PCA-FCM Clustering algorithm that can automatically determine the best clustering structure is also described in full. The results indicate that cellular abnormality provides changes to both the protein and nucleic acid vibrations. However, similar spectral profiles were identified for highly proliferating cells that were contained within reactive germinal centres of the lymph node. Chapter 3 provides a short introduction to the histology of the cervlx before presenting imaging results that were gained from the analysis of both healthy and diseased cervical tissue sections. The ability of each multivariate technique to discriminate different tissue types is discussed. In addition, the spectral features that are characteristic for each tissue type are described in detail. Novel imaging experiments upon exfoliated cervical cells are also presented. It would appear that cellular abnormality in cervical tissues and cells affects both the protein and nucleic acid features of the spectra. Glycogen and glycoprotein contributions that are prevalent in healthy tissues are also absent. Chapter 4 details sample preparation methods, the instrumentation and procedures used for data acquisition, and the subsequent data processing and multivariate techniques applied to analyse the collected spectral datasets.