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An attempt has been made to develop specialised flow injection analysis (FIA) systems for sulphate determination, and the determination of metals in trace quantities. The use of pH gradients and kinetic of recta in FIA systems is described, as is the use of single and double solvent extraction steps. The optimisation of the systems to improve sensitivity was carried out. The systems developed have many advantages over the static methods currently in use in analytical laboratories. Automation improves the precision and speeds up the analysis. Many of the chemical processes that classical "wet chemistry" involves have been automated, for example sampling, reagent addition, phase separation and absorbance measurement. The absorbance measurement was carried out using a phototransducer with LED light source. The detector cell is solid state. The inert stability of these components gives rise to very high sensitivity in colorimetric analysis. A system for the in-line measurement of pH is described. This was used to monitor pH gradients and the pH of solutions passing through the detector flow cell; for solvent extraction, and the mode of operation investigated. A robust easily constructed phase separator is described in single and double extraction systems, for the determination of trace quantities of uranium. The sulphate determination by turbidimetric analysis involved the use of alkaline EDTA. The build up of precipitated barium sulphate is minimised and interference masking is shown possible. FIA systems for the determination of copper(II), bismuth(III) and thorium(IV) with pyrocatechol violet are described. The pH effect was studied. Chelated zinc(II), copper(II) and nickel(II) with 1-(2-pyridylazo)2-naphthal(PAH) were extracted using single extraction system. Use was made of pH and kinetic effects to enable separate extraction of two metals from the same sample. The use of masking agents to allow the specific chelation of uranium in the presence of interferences was investigated. An indirect method using extraction of the uranium with tributylphosphate, then subsequent colour formation in the organic phase is described. The need for masking agents is thus minimised. The determination of the uranium content of ore is thus possible. A double extraction system for metal reconcentration was designed. The use of advanced optimisation and automation techniques is discussed.

The technique of mass-analyzed ion kinetic energy spectrometry (MIKES), in which ions are selected according to their mass-to-charge ratio before entering the electric sector of a mass spectrometer, has been used for structural studies on complex organic and biochemical compounds. This thesis contains three parts: (a) the application of MIKES to the structural elucidation of five unknown organic compounds; (b) an investigation to extend the MIKES technique to the structural analysis of specific portions of a molecule. Five steroids of known structure with similar ring skeletons and different side chains were studied. In each case, the ion products of the mass of the specific side chain was isolated by the MIKES technique followed by structural interpretation using the unique set of daughter ions in the MIKE spectrum. The ring skeletons were studied in the same way. The results demonstrated that unique parts of molecules can be isolated and their structures determined; and (c) the development of a new method, combining electron-impact pyrolysis mass spectrometry with the MIKES technique, for the structural elucidation of a complex biomacromolecule, deoxyribonucleic acid (DNA). This method (Py-EI-MIKES)' was used to study the structure of a modified nucleoside of unknown origin which is present in viral DNAs. Ion species from bacteriophage 0-174 DNA and lambda DNA were examined by Py-EI-MIKES. The MIKE spectra yielded evidence that a highly-modified nucleoside is present in both of these DNAs. The structure that the spectral data support is that of deoxy-Q*-nucleoside. Additional secondary projects resulted in: (a) a method for recognizing and eliminating extraneous peaks in MIKE spectra, and (b) a fast-scanning method for recording MIKE spectra under computer control for situations when the amount of sample and the time permitted for analysis are limited. This thesis contains four independent chapters and six publications.

This thesis reports the development and characterisation of the fast flow argon flow discharge source, coupled to quadrupole mass spectrometry, as a novel detector for gas chromatography. Also described are fundamental studies of the chemical and electrical properties of the flowing plasma, which further support the excited state model proposed in previous publications from this laboratory. The fast flow glow discharge source has been used for the GC-MS analysis of simple mixtures of halocarbons and organotin compounds. Detection limits in the low and sub-picogram range were obtained and the technique is shown to be a robust, simple and low cost alternative to existing plasma sources for elemental speciation. The voltage applied to the ion sampling cone has been used to easily control the degree of fragmentation of organic samples. When a small (< 10 V) <i>positive </i>bias was applied, molecular mass spectra were obtained with detection limits < 1 pg. When a <i>negative </i>bias was applied, the sample fragmented and dispersed the charge, which lowered the sensitivity. A progression to more fragmented ions was observed as the voltage was increased. This was similar to the type of information obtained from tandem mass spectrometry but only a single quadrupole was used in this work. The effect of the ion exit voltage on the organic ion intensities has been shown to be consistent with a secondary discharge of argon Rydberg (highly excited) states close to the sampling cone. When a negative bias is applied, the sample is fragmented in collisions with electrons accelerated in the field. When a positive bias is applied, positive ions are repelled but neutral molecular Rydberg species can pass through the exit aperture to the mass spectrometer, where they are then ionised. Therefore, the molecular mass spectra obtained may be considered as a form of Rydberg state mass spectrometry.

The main thrust of this work investigated the use of supercritical fluids in analytical chemistry. Their use for sample preparation, supercritical fluid extraction (SFE), and as a mobile phase in chromatography, supercritical fluid chromatography (SFC), was investigated for the analysis of compounds derived in the agrochemical and pharmaceutical industries. Fast, efficient separations were demonstrated with SFC for the analysis of pharmaceutical compounds and possible retention mechanisms in SFC are postulated. The hyphenation of SFE with SFC and mass spectrometry (MS) is successfully demonstrated in the analysis of a systematic fungicide from a soil matrix. Both qualitative and semi-quantitative data were obtained. A new atmospheric pressure ion source used in mass spectrometry, electrospray ionisation, was investigated for the analysis of both high and low molecular weight compounds. The technique afforded high mass measurement accuracies and the ability to be readily coupled with liquid chromatography. Experimental investigations were also made into the double ionisation energies of a series of chlorinated benzenes using double charge transfer spectrometry.

The objectives of these studies was to investigate the use of tris(2,4,6-trimethoxyphenyl) phosphonium (TMPP) derivatising reagents to enhance methods for the analysis of acids, alcohols and amines by high-performance liquid chromatography-mass spectrometry (LC-MS). Early chapters provide an introduction to the main instrumental techniques of chromatography, mass spectrometry and solid phase extraction used to conduct the experiments in the thesis. This is followed by a review of derivatisation for compounds analysed with HPLC and LC-MS. Particular emphasis is placed on tris(2,4,6-trimethoxyphenyl) phosphonium reagents. Chapter three provides experimental and instrumental details together with descriptions of the synthesis of the TMPP derivatising reagents. LC-MS studies on underivatised and derivatised compounds were conducted using electrospray ionisation (ESI) and atmospheric pressure chemical ionisation (APCI) with the positive ionisation mode providing to be the method of choice for derivatised compounds. Studies of carboxylic acids showed that derivatives formed with tris(2,4,6-trimethoyphenyl)phosphonum propylamine (TMPPPrNH₂) gave lower detection limits by LC-MS. The technique was successfully applied to the qualitative and quantitative analysis of the fatty acids composition of a variety of cooking oils and to the analysis of the fatty acids in soil extracts. Similar enhancement in sensitivity for LC-MS by ESI and APCI was observed for the TMPP derivatives of phenoxyalkanoic acid (PAAs) herbicides. Spiked water samples were studied using solid phase extraction and derivatisation of the herbicides were detected at low ng/L levels. Encouraged by these studies bile acids were next investigated and derivatisation of the carboxylic acid group with TMPPPrNH₂ provided enhanced sensitivity for LC-MS. The technique was successfully applied to the analysis of bovine bile for bile acids but taurine conjugated acids were not detected. TMPP derivatives provide improved methods for the analysis of acids, alcohols and amines by LC-MS using either ESI or APCI.

Non-spherical homogeneous particles in the 1.0 to 10.0μm size range are required for the calibration of aerosol shape analysis equipment based on light scattering principles (ASAS). A variety of particulate systems are needed, each with a uniform but easily definable morphology. An extensive literature review identified several chemical reactions which could be used for the production of uniform non-spherical particles in the specified size range. Small scale reaction schemes were devised to produce these particulate systems for an initial series of trials to assess their suitability as candidate materials for calibration of the ASAS. It was found that hematite particles produced by the hydrothermal ageing of ferric chloride solutions were highly suited to calibration purposes, as the particles could be prepared with either cuboidal or prolate spheroidal morphologies by slight modification in the reaction conditions. A research programme was then undertaken to establish the reproducibility of the ferric chloride reaction and the effects caused by further modifications and refinements in the reaction conditions. Highly homogeneous particles could be obtained only when reaction volumes of ten litres were used, giving hematite particles of cuboidal, spherical and prolate spheroidal morphologies, with aspect ratios of the prolate spheroids being variable from 1.0 to approximately 3.3. Magnetite and maghemite particles could also be produced by reduction and reduction/oxidation of the hematite particles with no change in the morphology of the particles. X-ray diffraction analyses confirmed the composition of these materials. The ASAS was challenged with these materials, demonstrating that it could recognise and distinguish between differently shaped homogeneous particles of the same material. It could also detect when particle orientation had occurred in the airflow carrying the particles through the laser beam. It was found that different degrees of particle orientation occurred for identical hematite, magnetite and maghemite prolate spheres. As the ASAS provided a measure of the degree of particle orientation, the operator was able to distinguish between these samples even though their size and shape characteristics were identical.

In Chapter 3 a homologous family of dialkyl phthalates is used to investigate the effect of plasticiser/polymer compatibility on the response characteristics of transparent, thin-film optical gas sensors for carbon dioxide. A strong correlation is found between plasticiser/polymer compatibility and sensitivity in phenol red/ethyl cellulose CO<SUB>2</SUB>-sensitive films. This relationship applies to CO<SUB>2</SUB>-sensitive films based on other polymers such as polystyrene and poly(methyl methacrylate). This relationship also extends to optical O<SUB>2</SUB>-sensitive films, implying that the relationship is general for thin film optical sensors. In Chapter 4 an optical sensor is developed for breath-by-breath gaseous carbon dioxide analysis. The detector is based on a general formulation described in previous work where a phase transfer agent, tetraoctylammonium hydroxide (TOAOH), is used to incorporate a hydrophilic pH-sensitive dye into a hydrophobic plastic film to create an effectively solid-state colourimetric sensor. In this work the formulation has been modified to yield a sensor which is capable of responding to clinically important levels of carbon dioxide (0.1-5%) in less than 200ms. This is comparable with the response of commercially available capnometers based on infrared sensing of carbon dioxide, which are currently widely used for clinical analysis. In Chapter 5 the hydrophobic bases, tetraoctylammonium hydroxide (TOAOH), tetrakisdecylammonium hydroxide (TKAOH) and tetradodecylammonium hydroxide (TDAOH), are used to solubilise the anionic form of <I>m</I>-cresol purple in ethyl cellulose to create colourimetric thin-film sensors for monitoring carbon dioxide in the gas phase and dissolved in solution. When used for making dissolved carbon dioxide measurements both TKAOH and TDAOH appear significantly more resistant toward interference by protons or other ions at high concentration when compared to TOAOH, the hydrophobic base which has been used for such work in previous studies. In Chapter 6 the preparation and characterisation of three different plastic thin-film colourimetric sensors for gaseous ammonia are described. Each of these film optrodes gives a reproducible and reversible response towards gaseous ammonia. The sensitivity of the film sensors was found to be dependent upon the pK<SUB>a</SUB> of the encapsulated dye. The sensitivity of the plastic film sensor decreases markedly with increasing operation temperature and the 90% response and recovery times are slow and activation-controlled.

This thesis describes the development and characterisation of two second-generation Fast Flowing Glow Discharge (FFGD) ion sources for analytical applications. These sources are interfaced with a quadrupole based mass spectrometer. Optimisation of the source parameters enables selective enhancement of the analyte ions whilst reducing the levels of the interfering ions (discharge gas and contaminant ions), producing a cleaner mass spectrum and higher analyte ion currents. Investigations have shown behaviour that is inconsistent with ionisation processes based solely on conventional models. This indicates that other ion-formation processes also occur within the argon glow discharge plasma, especially under short gas residence time conditions. Preliminary analytical work suggests that these sources achieve good internal precision (< 10%), detection limits in the 1-100 ppb range and Relative Sensitivity Factors in the range 0.4-5.0. These results indicate the potential of both sources for elemental analysis. The addition of 1-2% secondary hydrogen of the afterglow of the flowing plasma selectively enhances the metal ion signals. The interfering ions are also selectively reduced, to the point of negligible presence. These results are consistent with previous work from this laboratory, which suggests that the ions sampled from short residence time plasmas are as a result of neutral ionisation processes involving highly excited state species close to the ion exist aperture. Ionisation is caused by field/chemi-ionisation reactions at the ion exit aperture. The work in this thesis demonstrates that the Fast Flowing Glow Discharge source can be used as a sensitive elemental technique. In a separate piece of work, Collision Induced Dissociation Mass Spectrometry was used to investigate the pressure and temperature effects on the thermal (low energy) ionisation processes in cyclohexane. Although the project was unsuccessful in distinguishing the presence of the three C₆H₁₁⁺ isomers, the work is instructive with regards to the limitations of the technique used.

The equilibrium uptake of four amino acids (glycine, isoleucine, threonine, tryptophan) of differing physico-chemical properties on two ion exchangers of differing surface chemistries was studied with the aim of assessing the importance of inter-molecular and surface interactions in the ion exchange process. Analysis of data showed that, under the conditions investigated, the ion exchange of amino acids at hydrogen form cation exchangers occurred via the uptake of amino acid zwitterions and subsequent protonation of amino acid molecules within the exchangers. Equilibrium isotherm analysis allowed the determination of the thermodynamic equilibrium constants for each combination of amino acid and ion exchanger. The affinity of the synthetic organic resin (Dowex 50W) for the hydrophobic amion acid (tryptophan) was highest and lowest for the hydrophilic amino acid (threonine). The cellulosic ion exchanger (SE 53) displayed lower selectivity for all the amino acids compared to the Dowex 50W resin. This behaviour is explained by considering the chemical properties of the amino acids and ion exchangers. The heats of exchange of the amino acids at these ion exchangers were obtained by titration microcalorimetry using a Thermometric 2277 Thermal Activity Monitor. An analysis procedure was developed to determine the standard thermodynamic functions (ΔG<SUP>o</SUP>, ΔH<SUP>o</SUP>, ΔS<SUP>o</SUP>) for each ion exchange process. Knowledge of these thermodynamic quantities provided further insight into the interactions that can occur, in addition to the electrostatic interaction, during the ion exchange process. The thermodynamic data indicated the most effective means of manipulating process solution conditions in order to increase the selectivity of an ion exchanger for a particular amino acid and also to maximise the degree of separation between amino acids from a binary mixture. The techniques and data analysis procedures described are likely to be of use in the development of bioseparation processes.