A growing number of pollutants are being shown to have a large environmental and health impact resulting in stricter legislative limits. Increased environmental monitoring is forcing analytical chemists to consider automating and miniaturizing current standard methods. Instrumentation and sample handling techniques for centrifugal microfluidic devices in motion have been developed with the objective of integrating multi-step reactions into a single device for the analysis of environmental solid samples.In order to study and optimize centrifugal microfluidic devices in motion, motorized stages integrating a camera, strobe and a variety of other peripheral components were developed. These allowed precise control of the devices throughout the methods' spin sequences and simultaneous acquisition of a series of stop action photographs of the devices.Non-contact methodologies for sample introduction, preparation and extraction on centrifugal microfluidic devices in motion are presented. To achieve this, hybrid fabrication techniques including the use of 3D printers were investigated and a World-to-Disk interface permitting the introduction of a solution gradient to a spinning device was developed. The interaction of integrated mobile magnets with a series of fixed magnets placed below the spinning devices was also investigated resulting in the development of both a magnetically actuated solid sample preparation and a magnetically actuated liquid-solid extraction technique. New automated and miniaturized methods for the analysis of environmentally important species such as polycyclic aromatic hydrocarbons and pesticides in solid samples are presented. / Les polluants ont des impacts importants sur la santé et l'environnement résultant à des restrictions accrues des limites législatives. Cette surveillance environnementale accrue pousse les chimistes analytiques vers l'automatisation et la miniaturisation des méthodes de référence actuelles. L'analyse d'échantillons environnementaux solides bénéficiera de cette envolée par le développement de nouveaux instruments et techniques de manipulation d'échantillon via des dispositifs microfluidiques centrifuges qui intègrent des réactions à étapes multiples sur un dispositif unique.Afin d'étudier et d'optimiser les dispositifs microfluidiques centrifuges en mouvement, des plateformes motorisées qui incluent une caméra, une lumière stroboscopique et une variété d'autres composantes périphériques ont été développées. Celles-ci ont permis le contrôle efficace des dispositifs tout au long des séquences giratoires et l'acquisition simultanée de séries de photographies en arrêt sur image.Des méthodologies sont présentées pour l'introduction, la préparation et l'extraction d'échantillons sur des dispositifs microfluidiques centrifuges en mouvement. Ceci fut réalisé grâce à la recherche de techniques de fabrication hybrides incluant l'utilisation d'imprimantes 3D menant au développement d'une interface permettant l'introduction de solutés à concentrations variables aux dispositifs en mouvement. De plus, l'interaction d'aimants mobiles intégrés avec une série d'aimants fixes placée sous les dispositifs en mouvement a mené au développement des techniques de préparation d'échantillons solides par force magnétique et d'extraction liquide-solide d'échantillons par force magnétique. De nouvelles méthodes automatisées et miniaturisées ont été développées pour l'analyse d'espèces environnementales importantes telles que les hydrocarbures polycycliques aromatisés et les pesticides dans des échantillons solides.

The understanding of the interaction of light with a scattering/absorbing medium provides a foundation needed for developing many applications in diagnostic medicine and industry. The objective of this research was to obtain quantitative depth-resolved information about absorbing constituents in a scattering medium. / Initially, the project focussed on quantification in samples where scattering and absorber concentration were variable. Using time resolved reflectance measurements, a series of statistical descriptors of the photon time distributions were calculated. Stepwise multilinear regression was used to formulate linear models from optimal linear combinations of the descriptors. It was found that the scattering coefficient, absorption coefficient and apparent particle diameter could be estimated to within 9, 10 and 7% of their reference values respectively. / An array of radial reflectance measurements on layered scattering/absorbing samples was made to obtain information sensitive to sub-surface changes in absorption. As an initial approach to depth-resolved quantification, classical tomographic reconstruction techniques were used. However, due to the ambiguity of the reconstruction, extremely poor estimates of the sub-surface absorption resulted. Chemometric methods were then employed for enhanced quantification. By using stepwise multilinear regression with time-resolved data, the absorption coefficient in the top region of a sample could be estimated to within 2%. However, errors in the absorption coefficient estimations deep within a sample remained high. / Further improvements in sample quantification were made by linearizing the reconstruction problem. By using a priori information about sample composition in upper regions, subsequent calibrations for lower regions were directed. Estimations of the absorption coefficient deep within a sample with hierarchical locally weighted calibration were obtainable at greater than 50% accuracy. This represented a 20% improvement at all sample depths over stepwise multilinear regression. / Confocal illumination and detection optics was also used for discriminating highly scattered photons from light, which follows a geometric path through a sample. When confocal optics were used together with information from the rising edge of time distribution, little enhancement in quantification was observed in comparison to an integrated signal. This important finding demonstrates that the confocal optical detection should be considered when imaging in scattering/absorbing media.

Microfluidic platforms allow the implementation of classical analytical operations at a mere fraction of the time, cost and resources required conventionally while granting the potential for measurements to be taken directly in the field by untrained personnel. Centrifugal microfluidic (CM) platforms, a subset of microfluidic platforms, use centrifugal force to direct liquid flow and perform a variety of analytical operations.Although the use of centrifugal force grants CM platforms many advantages such as a high degree of parallelism, the potential for portability, and the capability to pump liquids irrespective of their physicochemical properties, it creates a design paradigm that requires all platform operations to occur while the platform is in motion. Stopping a CM platform may result in unintended capillary induced flow in channels that can disrupt the intended operation and even cause a loss of sample. In accordance with this paradigm, it is important to develop measurement techniques that can be utilized while CM platforms are in motion. One measurement of importance is the volume of liquid aliquots inside a CM platform. The capability to measure volume directly on CM platforms in motion could allow experiments to quantify liquid flow in real time and avoid the use of volume metering chambers, which occupy valuable platform space. In this thesis, a new technique based on image segmentation was created to perform volume measurements on CM platforms in motion. Evaluation platforms containing a black contrast layer were fabricated and injected with liquid aliquots. High-resolution images of the evaluation platforms in motion were obtained with a high speed camera synchronized to a strobe light and the images were processed digitally. Platform images were then converted to an intensity space before image segmentation was applied to trace the inner contour of each liquid aliquot. The contour of each measured aliquot was filled and an area was computed. This area was ratioed against that obtained for a calibration volume located on the same image to obtain the volume of the aliquot.The volume measurement technique was characterized through experiments designed to test its precision and accuracy over a range of volumes. The results were found to be 1 and 2% respectively. Further characterization of the technique revealed its flexibility in regards to optical magnification, chamber shape, size and aspect ratio and platform rotational frequency. An investigation into the effects of surface tension on the method precision was also conducted. The applicability of the technique to liquids of various colours was successfully demonstrated. The versatility of the method should allow it to be used for a variety of applications including real time metering of volumes in platforms, quantitative monitoring of a design's performance in real time and the elimination of metering chambers in designs. / Les systèmes microfluidiques permettent la miniaturisation de techniques classiques d'analyse chimique en n'utilisant qu'une fraction du temps et des ressources requises conventionnellement. Ces systèmes offrent la possibilité d'effectuer des mesures directement sur le terrain sans avoir recours à un personnel qualifié. Des systèmes microfluidiques ont été développés qui utilisent la force centrifuge pour diriger le débit de liquides injectés et accomplir une variété de processus analytiques. Bien que l'utilisation de la force centrifuge accorde à ces systèmes plusieurs avantages tels qu'un haut niveau de parallélisme, un potentiel de portabilité et la capacité de pomper des liquides indépendamment de leurs propriétés physicochimiques, elle crée aussi un modèle de conception qui requière l'accomplissement de toutes les opérations analytiques pendant que le système est en rotation.En accord avec ce modèle, il est important de développer des techniques de mesure qui peuvent être appliquées pendant qu'un système microfluidique centrifuge est en mouvement. Une mesure importante est celle du volume de liquides injectés dans un système microfluidique centrifuge. La capacité d'effectuer la mesure des volumes directement sur des systèmes microfluidiques en mouvement pourrait permettre la quantification du débit de liquide en temps réel et éliminer le besoin d'utiliser des chambres de comptage qui occupent un espace déjà restreint sur le système.Dans cette thèse, une technique basée sur la segmentation d'images a été développée pour mesurer le volume d'aliquotes de liquide dans des systèmes microfluidiques en rotation. Des systèmes d'évaluation contenant une couche de peinture contrastante ont été conçus, fabriqués et injectés avec des aliquotes de liquides. Des images de haute résolution de ces systèmes en mouvement ont été acquises avec une caméra numérique à haute vitesse synchronisée avec une lumière stroboscopique et traitées numériquement. Ces images ont été converties à un espace colorimétrique de niveau de gris et segmentées pour tracer un contour autour de chaque aliquote de liquide. Ces contours ont ensuite été utilisés pour calculer l'aire de chaque aliquote qui a ensuite été divisée par l'aire d'une aliquote de calibration située sur la même image pour obtenir le volume de chaque aliquote. La technique de mesure de volume a été caractérisée par des études conçus pour tester sa précision et son exactitude pour différents volumes. La précision et l'exactitude obtenues ont été de 1 et 2 % respectivement. Une caractérisation supplémentaire de la technique a révélé sa flexibilité quant au grandissement du système optique, la taille, la forme et le rapport hauteur/largeur des chambres du système et la fréquence de rotation du système. Une enquête sur les effets de la tension de surface du liquide mesuré sur la précision de la méthode a aussi été effectuée. L'applicabilité de la technique à des liquides de diverses couleurs a aussi été démontrée avec succès. La versatilité de cette méthode devrait permettre son utilisation dans une variété d'applications incluant la mesure de volumes en temps réel, le contrôle quantitatif de la performance de designs de systèmes microfluidiques centrifuges en temps réel et l'élimination de chambres de comptage dans leur conception.

A detailed, unified description of electrocatalytic mechanisms at organic conducting salt (OCS) electrodes, tetrathiafulvalene tetracyanoquinodimethane (TTFTCNQ) and hexamethylenetetratellurafulvalene tetracyanoquinodimethane (HMTTeFTCNQ), has been presented. A wide spectrum of behavior is observed depending on the electrochemical and kinetic characteristics of the analyte of interest, the nature of the OCS, and the applied potential. Both direct electron transfer and indirect (homogeneous and heterogeneous) mediation mechanisms are shown to arise, depending on the experimental conditions. / The redox chemistry of the coenzyme, pyrroloquinoline quinone (PQQ), has been investigated in detail as a function of metal complex formation and pH. The characterization of PQQ and its metal complexes provides insight into the redox chemistry of the 15-lipoxygenase active site. / A biosensor involving the coupling of a PQQ-enzyme, methanol dehydrogenase (EC 1.1.99.8.), to a TTFTCNQ electrode has been developed. Characterization of this enzyme membrane electrode shows that the substrate-reduced enzyme is rapidly turned over at the TTFTCNQ electrode whereas no turnover is evident at a conventional electrode. Enzyme properties (K$ sb{ rm me},$ stability, T$ sb{ rm sensitivity},$ pH dependence, substrate selectivity), when interfaced to the electrode, are reported.

Research on electrochemical detection methods for electroactive species in flowing streams is focussing on improving selectivity without compromising sensitivity or detection limits. With this in mind an effective electrode would be one that can examine electroactivity at many potentials in the shortest possible time frame. This work has investigated this possibility by using a single low temperature isotropic carbon working electrode with a choice of three scanning techniques. The most familiar one is cyclic voltammetry which is known to generate a wealth of qualitative information. The other modes are pulse and square-wave cyclic voltammetry. These modified versions of cyclic voltammetry offer advantages in two additional domains. Electroactivity may be studied in two time frames, increasing the diagnostic power, and quantitative determinations are possible. The enhancements and limitations of these scanning methods were investigated based on data obtained from a variety of electroactive model compounds. The survey was performed in quiet and flowing solutions using flow injection analysis for the latter.

The role of mobile phase modifiers in supercritical fluid chromatography (SFC) and their effect on the separation process were investigated. A study of the influence of temperature and density on chromatographic behaviour in supercritical carbon dioxide and four modified carbon dioxide mobile phases demonstrates the importance of both density and mobile phase composition in controlling retention characteristics. The information gained from these studies was used to develop methodology for the separation and detection of a series of phenothiazinone compounds and an assay for L-615,919, 4-chloro-3H-phenothiazin-3-one, in plasma. The development of an analytical method for the analysis of sorbitan trioleate in pharmaceutical formulations demonstrates a unique application of SFC with flame ionization detection (FID) that is not possible by other chromatographic techniques. / The feasibility of an electrochemical detection system for SFC has been demonstrated. The design and construction of an electrochemical detector with a platinum ultramicro working electrode and factors influencing its performance are described.

Formaldehyde is an important intermediate in the gas-phase methane oxidation chain and plays an important role in the chemistry of the troposphere by influencing the odd hydrogen budget (HOx = HO + HO2), and thus the Earth's oxidative capacity. The evaluation of the importance of formaldehyde in atmospheric cycles requires accurate and precise measurements of its concentration in the atmosphere. In this work, the concentration of formaldehyde in unpolluted outdoor air will be determined using an on fibre derivatization-solid phase micro-extraction (SPME). This method consists of derivatizing formaldehyde to its pentafluorobenzyl oxime using 1,2,3,4,5-pentafluorobenzylhydroxylamine (PFBHA), extracting using SPME and then analyzing with gas chromatography with flame ionization detector. We herein present an improved methodology for detection of formaldehyde in ambient air using SPME and GC-FID, which gives a detection limit of 100-300 pptv, for our rapid, portable and environmentally benign technique. The developed methodology was used to measure the formaldehyde mixing ratios in chemistry labs (9.28 ± 0.26, 12.36 ± 0.11 ppbv), library (11.75 ± 0.57 ppbv), and basement of a building (6.79 ± 0.010 ppbv) and in a campus terrain (7.17 ± 0.040 ppbv). We observed a diurnal variation in the mixing ratios of formaldehyde measured in the city of Montreal. The implications of our results will be herein discussed. / Le formaldéhyde joue un rôle important en tant qu'intermédiaire dans l'oxydation du méthane dans la phase gazeuse ainsi que dans les réactions chimiques de la troposphère en influençant le budget de radicaux hydroxyle et donc la capacité oxydative de l'atmosphère. Afin d'évaluer l'influence du formaldéhyde sur les cycles atmosphériques, la concentration atmosphérique exacte est requise et ce nécessite une méthodologie précise pour prendre des mesures. Dans ce travail la concentration du formaldéhyde dans l'atmosphère non polluée est mesurée à l'aide d'une fibre de micro extraction phase solide (SPME). Cette méthode consiste à dérivatiser le formaldéhyde en son oxime de pentafluorobenzyl avec du 1,2,3,4,5-pentafluorobenzylhydroxylamine (PFBHA), suivi par l'extraction et l'analyse par chromatographie phase gazeuse équipé d'un détecteur à ionisation de flamme (FID). Nous présentons une méthodologie améliorée pour détecter le formaldéhyde dans l'air ambiant à l'aide de la SPME et du GC-FID ; nous achevons une limite de détection de 100-300 pptv. La méthodologie a été utilisée pour déterminer les taux de formaldéhyde dans des laboratoires de chimie (9.28 ± 0.26, 12.36 ± 0.11 ppbv), dans une bibliothèque (11.75 ± 0.57 ppbv), dans le sous-sol d'un bâtiment (6.79 ± 0.010 ppbv), et sur un terrain au sein de l'université (7.17 ± 0.040 ppbv). Des mesures prises en 2009 au mois de juillet montrent que le taux atteint dans la journée et la soirée étaient de 8-12 ppbv et de 5-7 ppbv, respectivement; la méthodologie permet également de discerner les variations temporales.

Several approaches to sample preconcentration combined with sample introduction by Direct Sample Insertion (DSI) into the Inductively Coupled Plasma (ICP) for ultra trace elemental analysis have been developed. A microcolumn based flow injection (FI) manifold was used with ICP Mass Spectrometry (MS) but performance was adversely affected by high and variable blank levels. / Physical preconcentration by depositing the sample as an aerosol into an inductively heated graphite DSI probe yielded detection limit improvements of over two orders of magnitude for ICP Atomic Emission Spectrometry (AES). Instrumentation was developed to automate the aerosol deposition preconcentration process, and this apparatus was used in conjunction with ICP-MS. Several of the aerosol deposition, DSI, and ICP parameters that impact on the performance of the technique were studied. Detection limit improvements averaged two orders of magnitude, and analysis of a river water reference material for 10 elements gave good results even at the part per trillion (pg ml$ sp{-1}$) level. / Investigations into direct analysis of the analyte-laden chelating resin by DSI-ICP-AES were carried out. It was clearly demonstrated that the determination of volatile elements was adversely affected by the effect of the pyrolysis products of the resin on the plasma excitation conditions.

The initial and principal topic of this thesis was hazardous waste destruction by inductively coupled plasma (ICP) assisted post-combustion. As an aside, direct solid sample analysis (DSSA) on powdered sample was to be studied. To perform this double task, an "analytical chamber", described in chapter 2, was designed and made. The project was still at the preliminary studies stage on the usefulness of Swann bands as a probe for the presence of carbon to carbon bonds (Chapter 2), when the lack of funding forced a reorientation on the DSSA project as the main topic for the thesis. Since ICPs are known to be poor particle digesters, a suitable solid-gas reactor had to be found. From this study (Chapter 3), the cyclone reactor appeared to be the best-suited type of reactor for this task. Unfortunately, micro-engineering and gas flow rate constraints imposed by the ICP forced the abandonment of the concept for a simpler one. / In parallel with the quest for a suitable DSSA reactor, a new calibration method, the tandem calibration method (TCM) was developed. The objective of the TCM was to achieve calibration of any sample introduction system with the use of classical liquid standards. The study showed clearly that not only did the TCM not bias the results, but it also automatically corrected for physico-chemical matrix effects in a manner similar to standard additions. Despite the fact that results presented in Chapter 4 were obtained on liquid samples, the TCM is equally applicable to solid samples introduced into the plasma by other means. The TCM was used on an electrothermal vaporizer (ETV) (see Appendix 3). / The first DSSA system studied was modified direct sample insertion (MDSI). The MDSI used halogen-assisted sample vaporization and demonstrated that quantitative vaporization of solids could be achieved using the ICP as the thermal energy source (Chapter 5). The next step was to design a reactor along the same fines, but capable of operating under continuous sample feed from an appropriate powder feeder. This intraplasmic reactor, the pseudo fluidized-bed reactor (PFBR) did not perform as well as expected (Chapter 6). Still, it allowed the demonstration of the usefulness of a baffle placed in the path of the particles inside the reactor to achieve longer solid residence time. The results obtained on the PFBR indicated that although the general concept was good, the source of most problems came from inefficient energy transfer from the plasma to the reactor. This drawback was eliminated by replacing plasma heating with Ohmic (resistive) heating. Called the ohmically heated PFBR (OPFBR), this reactor imposed severe design constraints, principally in terms of electrode cooling and protection of the hot graphite reactor against attack from oxygen. The design required a series of modifications, described in Chapter 7, before reaching its final form (Chapter 8). Transport losses were a problem with the OPFBR. The introduction of a quenching gas through tangential holes in the upper body of the reactor faded to eliminate transport losses; however, these losses were sufficiently small and reproducible to allow quantitative analysis on real samples (SO-4 sod CRM and 1646 Estuarine sediment CRM) fed continuously into the reactor. These results fulfill the goal of this thesis, which was to develop a method for steady-state feed DSSA.

Two new techniques for the study of biological molecules using vibrational spectroscopy have been investigated, and are presented in this thesis in two parts. / In Part I, the application of centrifugal vacuum techniques for sample preparation in FT-IR spectroscopy is demonstrated. This technique is used in the development of an agglutination immunoassay for bovine serum albumin (BSA) using polystyrene latex particles as both a solid support and an IR label. The synthesis of new organometallic labels for use in LPIRIA has been undertaken and is described in detail. A competitive non-agglutination LPIRIA for BSA using anti-BSA covalently bound to carboxylate-modified latex (CML) particles has been developed. Protein-A, a universal antibody binder, covalently bound onto CML, is used in the development of a competitive non-agglutination LPIRIA for nortriptyline and for the titration of anti-theophylline by theophylline. / In Part II, the study of a variety of ($ eta sp{6}$-arene) chromium tricarbonyl complexes and cyclopentadienyl manganese tricarbonyl by FT-Raman spectroscopy is reported. The application of FT-Raman to the study of proteins, mycotoxins, latex particles, and selected drugs is also presented. (Abstract shortened by UMI).