Natural products provide a wide and virtually inexhaustible source of novel, useful, and often hard to synthesise compounds. However, due to the origin of these products, the matrices tend to be complex, and individual components are difficult to isolate and conclusively identify. The majority of this thesis focuses on the separation, identification, and quantification of certain species inherent within natural product samples. Liquid chromatography atmospheric pressure ionisation mass spectrometry techniques were utilised for this research. Chapter One provides a brief history and introduction to the principles and applications of liquid chromatography, mass spectrometry, and their use as an interfaced combined system. Chapter Two incorporates an investigation into the main component groups of cashew nut shell liquid (i.e. cardanol, cardol, 2-methylcardol, and anacardic acid). Compositional trends relative to the degree of applied heat treatment were examined. The compositions of certain regional samples were also compared. Chapter Three encompasses four synthesised phyto-oestrogen compounds known to naturally occur in plant-derived sources suspected as having potential cancer-protective activity. A separation of the four compounds is described, along with an account of their mass spectral identification and characterisation. Selected ion and selected reaction monitoring techniques were utilised for the determination of the limits of detection of each analyte. Chapter Four investigates the highly complex composition of propolis, a natural product manufactured by bees, and reported to provide a range of medicinal benefits. A liquid chromatographic separation of the substance is described. Additionally, differently sourced samples were mass spectrally analysed, and each one characterised and compared by their eight most abundant compounds. Chapter Five is an exception to the majority of the thesis and covers novel double-charge-transfer spectrometry investigations into the double-ionisation energies of acetonitrile and fluorinated benzene molecules. A brief appraisal of theorised values is also included.

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HPLC separations employing anion-exchange, reverse-phase and paired-ion techniques were developed for the analysts of both ribonucleotides and cyclic nucleotides. The methods for ribonucleotide separation were then optimised and evaluated for the analysis of extracts containing the free nucleotides of rat tissues. The nucleotide patterns of several tissues of the rat were then examined (a) In relation to ageing, over a period of 1 year from birth (b) in rats administered streptozotocin, a diabetogenic agent and (c) in rats administered doses of glucagon adrenaline and glucose. The effects of these compounds were investigated since they are known, like diabetes, to affect carbohydrate metabolism. During ageing, changes in the free nucleotide pattern were slight, but several trends did emerge. For example, the total nucleotide concentration (per 100g of tissue) in several organs declined with age. This was especially noticable with the concentrations of nucleotide-sugars. In streptozotocin induced diabetes the nucleotide pattern of the liver changed markedly, while those of heart and eye were only marginally affected. The nucleotide patterns of muscle and kidney appeared unchanged in the diabetic state. After administration of glucagon, adrenaline and glucose, the nucleotide profiles of liver showed several changes. The changes in nucleotide pattern observed in all the above cases are discussed with reference to biochemical changes which are known to occur in the relevant tissues as a result of the induced metabolic disturbances employed in the present study. Suggestions for further work on the nucleotide patterns of tissues are made. Suggestions are also made for the improvement of techniques for tissue sampling, sample preparation and HPLC analysis. These improvements might be used to facilitate detection of more subtle changes in tissue nucleotide patterns in subsequent studies.

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Silanophilic interaction chromatography columns can give rise to complementary selectivity compared to the more commonly used hydrophobic interaction based HPLC columns. However, the former types of phase have historically caused issues of tailing and irreversible retention with polar or basic analytes. An investigation was therefore undertaken into the fundamental nature of their electrostatic, dipole-dipole and hydrogen bonding interactions. This was particularly focussed on interactions that are induced by the presence of residual silanols on the surface of HPLC phases, in order to fully understand the retention mechanism and the practical limitations of commercial stationary phases. Manufacturer's literature for these types of phase often contains specific applications and claims, however full independent testing of a range of acid, basic, phenolic, and polar compounds had not previously been demonstrated . Research in this area will aid in the development of new industrial applications by highlighting the stationary phase type with the most suitable mechanism to separate any combination of polar and non-polar compounds. Initial investigations evaluated silanophilic interactions present in a set of Extended Polar Selectivity (EPS) phases utilising a set of known characterisation probes. Structural elucidation of these phases confirmed the intensity of these interactions is due to the accessibility of the silanols and the purity of the base silica. Shorter chains and sparsely bonded hydrocarbon ligands were shown to reduce hindrance and increase the degree of interaction. Endcapping was shown to decrease the accessibility of residual silanols and mask silanophilic interactions. High purity base silica was shown to reduce silanophilic interactions compared to similar phases bonded to a TVPE-A silica. The control and restriction of silanophilic interactions is of great importance for the analysis of basic and polar molecules. Commercial TVPE-C™ phases are claimed to minimise silanophilic interactions through the " silanization" process. This converts the surface silanols to silica hydride prior to derivatisation with a functionalised ligand.

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