The development of chromatographic methods for the detection of low molecular weight organic acids and inorganic anions found in low-order explosive residues are presented. The work is divided into six sections. Firstly, Chapter 1 provides a background on low-order explosives and fingermarks. Existing methods for the analysis of these sample types, focussing on ion chromatography (IC) and mass spectrometry (MS) technologies, are reviewed. Gaps in knowledge are highlighted and the aims and objectives of the thesis presented and justified towards addressing these challenges. Chapter 2 applies an anion exchange chromatographic method for the analysis of gunshot residue. This micro-bore scale method utilises a hydroxide gradient with suppressed conductivity detection. A study on external contamination, such as from environmental matrices and collection devices, is presented suggesting that direct extraction of the residues is more advantageous for the analysis of these residues on small items. Analytical performance characteristics for linearity, repeatability and limits of detection are also presented and discussed. Chapter 3 extends the performance limits of IC by investigating the use of capillary-scale IC technology for the detection of low-order explosive residues for the first time, including gunshot residues and black powder substitutes, in biological matrices such as sweat and human latent fingermarks. A comparison to the micro-bore method in Chapter 2 is made, with a focus on the measured increase in absolute sensitivity at the lower limits. In a brief study, a capillary-scale organic polymer monolithic resin (IonSwift MAX-100) was also investigated in terms of backpressure and efficiency. Chapter 4 presents the selectivity offered by alternative anion exchange resins with the addition of organic solvents to the eluent, specifically methanol and acetonitrile. The combined effect of temperature and organic solvent-containing eluents on IC selectivity is also presented for the first time and discussed regarding their use as variables in IC method development. Analytical performance characteristics for linearity, repeatability and limits of quantification are presented. Chapter 5 combines the organic solvent and temperature-enhanced IC method developed in Chapter 4 with high resolution mass spectrometry (HRMS) detection which enabled simplified coupling of these two technologies. The method was applied to the forensic detection of low-order explosives in fingermarks for the first time, offering confirmatory analysis of several forensically important species at pg amounts. Analytical performance characteristics for linearity, repeatability and limits of quantification are once again presented and compared to the published literature. Chapter 6 presents results collected by capillary electrophoresis and Raman spectroscopy as alternative/complementary techniques to IC. These techniques are applied to the detection of explosive residues in biological matrices, and their relative merits are discussed. The development of several IC-based technologies enabled the successful interrogation of small anions in low-order explosives within fingermarks at fg-ng amounts for the first time, offering the potential to link identity with criminal activity. In particular, the development of a solvent enhanced-IC method with simplified coupling to HRMS shows considerable benefit not just for forensic purposes, but for IC applications in a number of alternative fields.

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The first set of measurements in this thesis discusses the hydrogen-bonding behaviour of1,3-dimesitylimidazol-2-ylidene when co-crystallised with organic acids. 1,3-dimesityiimidazol-2-ylidene is an unusual molecule in which it is possible to have a carbon with a valence of two. In the co-crystals of 1,3-dimesitylimidazol-2-ylidene with pentafluorophenol, pentachlorophenol, 2(2-hydroxidophenyl)benzoxazole or 2,6-di-tert-butyl-4-methylpyridine the 1,3-dimesitylimidazol-2-ylidene becomes protonated and uncommonly short C-H - O hydrogen bonds are formed, the shortest has a C-0 separation of 2.800(3)Å. In the 1:1 co-crystal of 1,3-dimesitylimidazol-2-ylidene and diphenylamine the first example of an N-H-C hydrogen bond is observed, with an N-C distance of 3.196(2)Å. The 1:1, 1:2 and 2:1 co-crystals of 4,4'-bipyridine and benzene-1,2,4,5-tetracarboxylic acid(pyromellitic acid) have been studied by X-ray and neutron diffraction and the 1:1 and 1:2 co-crystals of 4,4'-bipyridine and benzene-1,2-dicarboxylic acid (phthalic acid) and the 1:2 co-crystal of bis-1,2-(2-pyridinium)ethane and benzene-1,2-dicarboxylic acid have been studied by X-ray diffraction. In the short N-H- -0 hydrogen bond observed in the 2:1 co-crystal of 4,4'-bipyridine and benzene-1,2,4,5-tetracarboxylic acid (N-0 2.5220(17)Å at 20K) the hydrogen atom was observed to change position with temperature; at 20K the hydrogen lies1.207(3)Å from the nitrogen and 1.325(3)Å from the oxygen and at 296K it has moved across the hydrogen bond to lie 1.240(4)Å from the oxygen atom and 1.302(4)Å from the nitrogen atom. The same phenomenon of temperature dependent proton migration has been observed by neutron diffraction in crystals of pyridine-3,5-dicarboxylic acid and upon deuteration of the hydrogen bonds the magnitude of the effect becomes greater. Solid-state density functional theory calculations have been used to provide theoretical models for the observed behaviour and to predict the inelastic-incoherent neutron-scattering spectra for pyridine-3,5-dicarboxylicacid in different degrees of deuteration.

A ratiometric, luminescent Eu probe was sought for use in measuring intracellular pH, that can be excited in the range 355-405 nm. In order to achieve this, a series of 1- azathiaxanthone based chromophores has been synthesised and studied to find the best candidate to promote Eu emission. A series of 'D02A' derivatives was synthesised incorporating both the chosen chromophore (2-methyl-l-azathioxanthone) and a pH- dependent binding moiety (a tethered sulfonamide). Measurements were carried out in order to study and understand the properties of the complexes, especially the nature of the pH dependence. The protonation constants of the pendant pH 'switch' in each system were determined by luminescence titration. The influence on Eu emission of some endogenous anions and protein has also been examined by luminescence spectroscopy, along with calculations of their apparent binding constants in order to find the best candidate for measuring intracellular pH. A novel bicarbonate sensor has also been synthesised and studied incorporating a 7-(methylcarbamoylmethyl)-azathioxanthone sensitiser moiety. The luminescence properties have been thoroughly studied, and the changes in the photophysical properties and the sensitivity towards anion and protein binding rationalised. The complex displayed sensitivity towards endogenous anions and protein binding, however, a suitable calibration curve was obtained in the desired 5 - 30 mM HCO(_3) range in simulated endogenous anion mixture, using intensity ratio vs. pH plots. A series of ratiometric Eu(111)complexes has been synthesised incorporating an efficient sensitiser for measuring citrate concentrations in seminal and prostate fluid samples. Their luminescent properties were thoroughly studied using simulated prostate fluid as the background to find the best candidate for prostate adenocarcinoma detection. Preliminary studies have been undertaken to determine citrate levels in 'clinical' prostate and seminal fluid samples. Cellular uptake and localisation studies have also been undertaken with each complex revealing the complex uptake profile and the time-dependent localisation behaviour within the cell. Each complex showed no significant evidence for toxicity. Images were observed using unfixed cells, appropriate for live cell imaging applications.

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A Monte Carlo has been developed, using the EGS4 code, to aid the design and optimisation of a polarised source for <I>in vivo</I> X-ray fluorescence (XRF) analysis of platinum (P<SUB>t</SUB>). The modelled code is based on a 300 kV clinical X-ray therapy unit at Singleton Hospital. The code handles five individual components (X-ray tube, filter, polariser, sample and detector) which the user assembles as needed, thus allowing the facility for simulation of a wide variety of XRF systems. For each component, all the physical dimensions and materials involved are set by the user. The model includes polarised photon transport modification, K-edge fluorescent photon transport modification and K-edge sampling method for mixtures (a facility previously available for simple compounds). It incorporates a variance reduction technique (forcing photon interaction) and uses random number generator called RANMAR. Also EGS4PICT (The EGS4 Shower Display System for PC) is built in to display a shower picture at every stage of simulation. The clinical motivation for the measurement of Pt is the need to investigate the kinetics of Pt-based chemotherapy drugs used for the treatment of head and neck tumours in cancer patients. Accurate measurement of tumour Pt concentration can provide important information in establishing dose-response relationships and therefore optimising treatment to obtain maximum therapeutic effect. Several computer experiments are employed to find optimum geometrical configuration and maximise sensitivity for the polarised XRF system. The selected polariser materials tested are C, Al, Fe, Cu, Sn and Pb. The material shape and thickness is investigated. The secondary beam collimator diameter, length and material is also studied. Results are compared with analytical models and experiment.

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