This thesis covers in detail the literature on the theoretical aspects of electrodriven separation in capillary electrophoresis (CE) and capillary electrochromatography (CEC), the column technology of CEC including different types of stationary phases; open-tubular (coated columns), packed and continuous-bed (monolith). The literature on the coupling of CE/CEC with mass spectrometry (MS) and their advantages are also covered. The thesis also describes the preparation and the characterisation of polymethacrylate monoliths. Butyl methacrylate and sodium sulphite-based monoliths with negative surface charges were prepared: The former derived the charge from the sulfonic acid moieties of the 2-acrylamido-2-methyl-l- propanesulfonic acid (AMPS) while the second derived the charge from the sulphite group of the sodium sulphite introduced by epoxide ring opening. This negative charge is responsible for the generation of electroosmotic flow (EOF).

The single cell gel electrophoresis assay (comet assay) has been widely used over the last 30 years. It is a robust method of estimating DNA movement under perturbation. In the assay cells are embedded in agarose on a frosted slide. The amount of broken or fragmented DNA that is removed from the central body, after the cell has been lysed and electrophoresed, is estimated as the total volume of DNA damage in the form of strand breaks caused by the insult. The damage is quantified by fluorescence microscopy with analysis software. It is a simple technique that is efficient and relatively quick. With the comet methodology there is much debate on the underlying mechanisms of cellular damage and repair and over how strongly the comet shape reflects the DNA damage that has occurred. It is often used as a quick-fire detection method to back up other analysis methods with very little thought given to the information it provides. The technique itself is open to experimenter bias at the microscopy level, where researchers have the freedom to select which comets to analyse. Addressing these issues along with those of standardising the technique and developing novel methods of comet analysis may enhance the information it provides. Using statistical and computational methods, it is proposed that a simulation of the comet would provide important information about DNA damage at a cellular level while offering impartial judgement and reproducibility. Information is available on some aspects of comet structure in published literature and with new techniques both computationally and experimentally it has become possible to examine intrinsic information on comet structure. Information was also established via novel and existing laboratory techniques and also through microscopy techniques to examine architecture. A computational modelling and simulation approach can then be used to ask important biological questions on aspects of DNA damage and repair at a cellular level.

No description available.

The work presented in this thesis involves the utility of room temperature ionic liquids (RTILs) as solvents in electrodeposition of Alkali Group I metals (excluding Fr). The first two chapters present fundamentals of electrochemistry which is the basis of this work followed by an overview of RTILs and a brief introduction to X-ray photoelectron spectroscopy. The results of five original studies are then presented as follows: • The deposition and stripping of Li/Li⁺ couple in several RTILs is studied in detail on Pt and Ni microelectrodes and the results are simulated using a mathematical model developed by the Compton Group • The study is then continued for Na/Na⁺ in several ionic liquids on a Ni microelectrode and the results are compared to that of Li/Li+ couple • The remaining members down the Group (K/K⁺, Rb/Rb⁺ and Cs/Cs⁺) are studied in ionic liquid N-butyl-N-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide ([C₄mpyrr][NTf₂]) on a Ni microelectrode allowing comparison of electrode potentials throughout Group in the IL to be deduced. • The novel development of in situ electrochemical-X-ray photoelectron spectroscopy for monitoring the potassium deposition is reported • Electrochemical-XPS is used for monitoring rubidium deposition in competition with RTIL solvent breakdown The results presented show that several RTILs are able to support the electrodeposition of Alkali Group I metals due to their wide electrochemical windows and electrochemical stability. The simulation of the results allows thermodynamic and kinetic parameters such as the electrochemical rate constant (k⁰), diffusion coefficient (D), and formal potential (E_f⁰) and transfer coefficient (α) to be extracted. The trend in electrode potentials of the Group in [C₄mpyrr][NTf₂] is also presented and compared to that of in other solvents. The near zero vapour pressure property of the RTILs is also exploited for the development of in situ electrochemical-XPS; a new branch of spectroelectrochemistry.

The development of an offline interface platform for continuous fraction collection from capillary zone electrophoresis (CZE) is presented. The platform is specified for Proteome-On-Chip applications that employ the protein quantification and differentiation technology Electron-Vibration-Vibration Two-Dimensional Infrared (EVV-2DIR) spectroscopy as the primary protein analysis tool. It is demonstrated that the interface platform facilitates preservation of an initial CZE separation effort and enables generation of single and multi-component tracks that are accessible to examination using EVV-2DIR spectroscopy and intrinsic fluorescence imaging (IFI) microscopy. With the introduction of a novel signal detection substrate, it is shown that EVV-2DIR spectroscopy facilitates detection and differentiation of post-translational modifications, and in particular phosphorylations of tyrosine moieties in polypeptides. The results of analytical and bioinformatical procedures performed on data generated with the interface platform-connected tool set suggest that a continued development of this modular proteomics-driven strategy may offer potential to successfully engage in proteomics projects. Furthermore, it was found that CZE, in addition to electrophoretic separation, also facilitates molecular sizing of the components constituting a complex mixture in a single process step. Despite the absence of an externally applied hydrodynamic flow field, a direct proportionality between protein molecular weight and dispersion coefficient is observed. This qualitative resemblance to the phenomenology of Taylor-Aris dispersion, together with a derived radial temperature gradient (dT)R > 103 K/m and resulting Peclet numbers Pe > 102, is interpreted to be due to Joule heating-induced Taylor-Aris dispersion. For single, as well as for multi-protein solutions, the employed experimental conditions facilitate a mean accuracy of the method of 70 %. The method is independent of the type of solvent or buffer systems employed, and thus experimental parameter optimisation may enhance the accuracy to a degree in order to be useful in the application of proteomics strategies as stated above.

No description available.

The aim of this work was to investigate the possibility of controlled bottom-up electrodeposition of metals into nano dimensional spaces from supercritical fluids. Initially, it was necessary to choose a solvent or a mixture of solvents that would be a suitable base for an electrolyte solution. This was followed by the choice of supporting electrolytes and metal precursors. An attempt to find an appropriate reference electrode or an internal reference probe was also made. Cyclic voltammetry with microelectrodes was used to study the supercritical systems with metal complexes prior to the electrodeposition experiments. The most suitable metal (silver and copper) complexes were employed in the electrodeposition of metal films on flat electrodes. This was followed by electrodeposition into templated substrates, namely aluminium oxide membranes (20-400 nm diameter cylindrical pores) and hexagonal mesoporous silica thin films (3-5 nm diameter pores). The first nanowires produced in homogenous supercritical fluids are reported.

This thesis discusses diverse electrochemical strategies for the determination of the concentration of the gases hydrogen sulfide, ammonia and halothane. The chemical tagging of sulfide by a variety of structurally diverse substituted benzoquinone species was studied over a wide range of pH (2<pH<10). Each derivative was found to respond to increasing concentration of sulfide (typically over a range 10-200 μM). The electrochemically initiated reaction of N,N-diethyl-pphenylenediamine (DEPD) with sulfide in N,N-dimethylformamide (DMF) was next examined with quantitative detection of sulfide (linear range= 28-3290 μM, LoD= 22 μM) achieved by analysis of the increase in the second oxidation wave. This is consistent with the sulfide attacking the doubly oxidised species in a 1,4-Michael addition. The direct oxidation of sulfide at a nickel hydroxide film on a nickel electrode in alkaline solution has provided the basis for the design of a simple and inexpensive sensor for monitoring H₂S in the range 20-200 μM. More sensitive (LoD= 1 (μM) amperometric detection of sulfide was obtained at modified nickel electrodes in acidic media in which sulfide was stripped from the nickel oxide layer. This approach was exploited further by using nickel modified screen printed carbon (Ni-SPC) electrodes as economical and disposable sensors for sulfide. Next, two different strategies for determining gaseous ammonia in the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluromethylsulfonyl)imide, [EMIM][N(Tf)₂], and in DMF are described. The first approach exploits the effect of ammonia as a proton acceptor species on the anodic oxidation of hydroquinone, resulting in a linear detection range from 10 to 95 ppm ammonia (LoD= 4.2 ppm). The second approach is based on the direct oxidation of ammonia in either DMF or [EMIM][N(Tf)₂]. The possibility of photochemically induced electrocatalytic processes within microdroplets containing p-chloranil (2,3,5,6-tetrachloro-1,4-benzoquinone, TCBQ) was examined as a means of detecting the anaesthetic gas halothane.</p> Finally, two of the more promising routes for sulfide detection were studied at elevated temperatures (up to 70 °C) with a view to developing H₂S sensors capable of meeting the demands of oilfield applications.

Il y a un intérêt croissant concernant la découverte de nouvelles méthodes commercialement viables pour réaliser des analyses spectro-électrochimiques — combinant des techniques électrochimiques et spectrales. Pour ce faire, nous avons préparé un matériau d'électrode transparent et conducteur, l’oxyde d’indium dopé à l’étain. Nous avons utilisé la technique d’électrofilage conduisant à la formation de fibres très fines avec une surface spécifique élevée. Ces électrodes ont ensuite été recouvertes d'une couche supplémentaire de silice poreuse et fonctionnalisée pour maximiser la surface spécifique et introduire des propriétés de détection supplémentaires. Le dispositif a été utilisé dans la détection du bleu de méthylène qui est un colorant industriel mais également un polluant environnemental. il a été mis en évidence qu’avec l'utilisation d'une telle électrode, il était possible de détecter des concentrations inférieures aux niveaux environnementaux nocifs. Enfin, les électrodes fonctionnalisées ont également été utilisées avec succès pour générer une luminescence plus intense et plus stable, ce qui ouvre de nouvelles perspectives pour la conception de capteurs spectroélectrochimiques / There is a growing interest in finding new and commercially viable methods of performing a spectroelectrochemical analysis which combines electrochemical and spectral techniques. For this purpose, an electrode material that is transparent and conductive needs to be prepared. In this work, such electrode was prepared by electrospinning which is a technique capable of forming very thin fibers with high surface area. Those electrodes were also covered with additional layer of porous and functionalized silica to maximize the surface area and introduced additional sensing properties. This material was used in the detection of methylene blue which is an industrial dye and an environmental pollutant. It was found that using such electrode it was possible to detect concentrations that are smaller than the harmful environmental levels. Finally, the layers were also used with success to generate luminescence which is opening new prospects for the design of spectroelectrochemical sensors

Les analogues du bleu de Prusse contenant du Fe et du Co (Fe/Co PBA) sont des complexes moléculaires qui présentent des propriétés physiques bistables. Par conséquent, ils sont considérés comme des candidats potentiels pour le stockage d'informations à base de molécules. Cette thèse vise à étudier la structure électronique et magnétique de Fe/Co PBA en utilisant des techniques expérimentales et théoriques avancées. Les techniques X-ray Absorption Spectroscopy (XAS) et X-ray magnetic circular dichroism (XMCD) combinées avec la théorie des multiplets en champ de ligands (LFM) sonde le changement dans les propriétés magnétiques macroscopiques de Fe/Co PBA et peuvent donner des informations locales sur les centres métalliques des complexes. Le composé tridimensionnel RbCoFe PBA, deux complexes de dinucléaire photomagnétiques et les précurseurs de Fe sont étudiés. L'étude de XMCD combinée avec la LFM a révélé une grande valeur du moment magnétique d'orbite du précurseur FeTp. Une étude détaillée a été effectuée pour vérifier les règles de somme d'orbite et de spin dans le cas des ions de Fe(III) bas spin et il a été constaté que la règle spin somme n'était pas valide à cause de l'entremélange des seuils L2 et L3. L'enquête XMCD des complexes dinucléaires photomagnétiques a confirmé le transfert d'électrons métal-métal. Cette enquête XMCD de la plus petite unité de la famille Fe / Co PBA est utile pour comprendre les propriétés magnétiques de la famille de Fe / Co PBA. L'étude XMCD sur aux seuils K du Fe et du Co d'un composé tridimensionnel RbCoFe PBA a prouvé l'existence d'une interaction antiferromagnétique entre les ions métalliques de Fe et de Co dans l'état photoinduit. / The Fe/Co Prussian Blue Analogues (PBA) are molecular complexes that exhibit externally controlled bistable physical properties. Thus, they are considered as potential candidates for photoswitchable molecule-based information storage. This thesis aims to investigate the electronic and magnetic structure of Fe/Co PBA using advanced experimental and theoretical techniques. X-ray Absorption Spectroscopy (XAS) and X-ray Magnetic Circular Dichroism (XMCD) techniques combined with Ligand Field Multiplet (LFM) theory probe the change in the macroscopic magnetic properties of PBA and can give local information about the metal centers existing in the complexes. The XAS and XMCD spectra at Fe and Co L2,3 edges are simulated using Ligand Field Multiplet (LFM) Calculations. The tridimensional RbCoFe PBA, two photomagnetic dinculear complexes and the building blocks Fe-bearing precursors are investigated. The XMCD study combined with LFM investigation revealed a large value of orbital magnetic moment in FeTp precursor of the dinuclear complex. A detailed study has been performed to check for the orbit and spin sum rules in the case of low spin FeIII ions and it was found that the spin sum rule does not hold because of intermixing between L2 and L3 edges. The XMCD investigation of the photomagnetic dinuclear complexes confirmed the metal-to-metal electron transfer. This XMCD investigation of the smallest unit of Fe/Co PBA family is helpful to understand the magnetic properties of the family of Fe/Co PBA. The XMCD study at Fe and Co K edges of a tridimensional RbCoFe PBA proved the existence of an antiferromagnetic interaction between Fe and Co metal ions in the photoinduced state.