Electron impact induced rearrangements have been observed in compounds containing either two arylthio groups or an arylthio group and an arylsulphonyl group. In addition to the loss of sulphur dioxide from the molecular ion and a sulphone-sulphinate rearrangement, 3-arylsulphonyl-2-arylthiopropenes exhibited the rearrangement a bisarylsulphide ion (analogous to that reported for the isomeric l-arylsulphonyl-2-arylthiopropenes). A series of l-arylsulphonyl-4-arylthio-2-butynes also underwent sulphone-sulphinate rearrangement and rearranged to the bisarylsulphide ions, in the absence of sulphur dioxide or sulphur extrusion. The formation of the bisarylsulphide ion from the molecular ion of these compounds is postulated to occur after an initial {1,3} arylthio shift giving an ion analogous to the molecular ion of 3-arylsulphonyl-2-arylthiopropene. A skeletal rearrangement of N-(4'-arylsulphonyl -2 '-butynyl)-N-(4"-arylthio-2"-butynyl)anilines resulted in the elimination of Ar1SO2SAr2 from the molecular ion, but notions arising from a sulphone-sulphinate rearrangement or extrusion of sulphur or sulphur dioxide. The rearrangement of N,N- bis(4'-arylthio-2'-butynyl)anilines via consecutive {1,3} arylthio shifts,followed by elimination of a bisaryldisulphide moiety, was supported by the behaviour of N-(4'-arylthio-2'-butynyl)-N-(2"-arylthio-2"-propenyl)-p-toluidines and N,N-bis(2'arylthio-2'-propenyl)-p-toluidines. Theirmolecular ions are analogous to the rearranged molecular ions of the N,N-bis(4'-arylthio-2'-butynyl)anilines after one or two arylthio shifts, respectively. No extrusion of sulphur is observed, but rather the elimination of a bisaryldisulphide moiety occurs. A series of 1,8-bis(arylthiomethyl)naph-thalenes and 1,2-bis(arylthio)acenaphthenes were1 2synthesised. Electron impact showed no loss of Ar SSAr from the naphthalene derivatives, owing to the predominance of C-S bond cleavage. However, the acenaph-thene derivatives readily eliminated a bisaryldi-sulphide moiety and a qualitative substituent effect was1 2 +observed for the formation of Ar SSAr ˙ ions. In a separate investigation, the kinetics of ion-molecule clustering reactions in a number of chemical ionisation reagent gases were studied. Rate coefficients were obtained at various ion-source field strengths for the formation of proton or deuteron bound dimers at pressures of ca.0.01-0.4 Torr (450°K).Changes from overall third to second order kinetics were observed with increasing pressure, in accord with an energy transfer mechanism. Using the higher values of pressure, rate coefficients were obtained and corresponded to the formation of the excited collision complexes. Rate coefficients for the association reaction of the MH (or MD ) ions in methylamine, dimethylamine, trimethyl-Simple kinetic methods for estimating the ion-source pressures of these gases are described. The disappearance rate coefficients for the major primary ions of the above gases were also determined.

This study may be divided into two sections which cover different aspects of the reproducibility problems encountered in HPLC. In the first, the study has involved the separation of basic drugs, on different manufacturer's reversed-phase columns in conjunction with an acid buffered acetonitrile/water gradient. The retention reproducibility of each drug was assessed and compared on the basis of the retention index scale of 1-nitroalkanes. The effect of changing gradient run time on the reproducibility of the retention values of the 1-nitroalkanes was demonstrated on reversed-phases of different makers. The optimisation of initial isocratic composition of organic (acetonitrile) was carried out and its effect on the reproducibility of retention of basic drugs was evaluated. The effect of a premixed eluent on the retention reproducibility of selected basic drugs with time intervals between injections was demonstrated. The same method was further extended with or without using helium gas with small flow. The prediction of dwell volume and its effect on retention reproducibility was evaluated. Determination of retention times changes for selected aqueous basic solutes against eluent with different pH values on Capcell ODS column was studied. Applicability of each reversed-phases (Cl8) for the separation of basic analytes was demonstrated. In the second section, a number of different unbonded (bare) silicas were studied in terms of surface analysis using of solid state cross-polarisation (CP) magic angle spinning (MAS) NMR and Fourier Transform (FT) Diffuse Reflectance Infrared Spectra (DRIFT-IR) data. It is believed that silica material used for HPLC separation with eluent undergoes an ageing process with acidic (at pH:2–3) and basic eluents (higher than pH:8). To examine this process more clearly, some basic analytes were selected to evaluate each of the accelerated ageing process followed by showing the final surface properties by the method most commonly used such as solid-state NMR and FT-IR along with BET surface analyser.

The application of flow injection analysis into the simultaneous determination of two or more components has been challenging for many years. Various detectors such as ultraviolet/visible absorption, fluorescence, and electrochemical detectors, have been used individually or in combination with each other. Combining two optical detectors such as fluorescence and ultraviolet/visible absorbance, however, has always been challenging due to their incompatibilities. However, the recent developments in fibre optics, solid-state light sources and miniaturised charged coupled devices (CCD), allow novel designs and most of the incompatibilities be circumvented. A flow injection manifold can now be adapted so that only one flow cell is used along with a diode array CCD detector that can detect both fluorescence and absorbance simultaneously. The initial development and testing of such dual detection system is described in this thesis.

Even at low concentrations the presence of toxic materials, such as metals or organic pesticides, in water can be harmful to humans. Extraction and preconcentration of these materials is an important part of many analytical procedures. In this work functionalised solid phase extractants, 250 nm in size (nanoscavenger), have been used to collect and concentrate metals and organic species from water using a nanoscavenger dispersion extraction (NSDE) approach. Stöber-type silica with a mean diameter of ca. 250 nm and a surface area of ca. 20 m2 g-1 has been synthesized by hydrolysis and condensation of tetraethoxysilane in a methanol and ammonium hydroxide medium. Increasing the surface area to increase the loading of functional groups on the surface was achieved by adopting mesoporous silica as the nanoscavenger core. This was successfully synthesized from tetramethoxysilane in the presence of a dodecyltrimethylammonium bromide template: 250 nm particles prepared in this manner had a surface area of ca. 1325 m2 g-1. The properties of synthesized sub-micron silicas have been investigated using various techniques. One of the main aims of this work was to use the nanoscavengers for the analytical recovery of trace analytes from water. Nanoscavengers were prepared by chemically modifying mesoporous silicas with groups such as mono- and diamines, dithiocarbamates, hydroxyquinoline, mercaptobenzamide and, for organic extractions, a mixed functionality diol and C18 modification. The nanoscavengers were characterized by Fourier transform infrared spectroscopy, scanning electron microscope, transmission electron microscope and thermogravimetric analysis. Copper capacity measurements for complexant nanoscavengers ranged between 0.1 and 2 mmol g-1 depending on the type of silica and the loading group. The nanoscavengers were evaluated for the preconcentration of trace analytes from water. The dithiocarbamate, hydroxyquinoline and mercaptobenzamide nano- scavengers were used to preconcentrate eight metal ions (Cu2+, Cd2+, Ni2+, Pb2+, Co2+, Cr3+, Mn2+ and Zn2+) from water. A dual functionality diol/C18-nanoscavenger was used to collect four estrogenic compounds, polynuclear aromatic hydrocarbons and tributyltin from water. The recovery of extracted analytes by nanoscavengers exhibited good results.

This thesis reports the development and potential applications of direct UV written Bragg grating refractometers for detection of chemical analytes. The technique of direct UV writing uses the localised refractive index increase of a photosensitive planar glass layer upon exposure to a tightly focussed UV beam to fabricate a wide range of integrated optical devices. One such device, the Bragg grating, can be used as an optical sensor for changes in refractive index. This thesis reports upon the advancements made to such optical Bragg grating devices towards the development of practical “lab-on-a-chip” microfluidic chemical sensors. This has been achieved through improvements in the fabrication processes and the inclusion of a high-index overlayer, shown to enhance the sensitivity by over an order of magnitude. A novel method for compensating for fluctuations in temperature is introduced; with it demonstrated that this technique can be applied towards the fabrication of an athermal Bragg grating device. The encapsulation of such highly sensitive refractometers within a microfluidic channel allows for realtime measurements of the dynamic composition of a fluid. This technology has been further developed to allow for chemical reactions to both occur, and to be monitored upon the microfluidic sensor surface. It is also demonstrated that using such a functionalised surface allows for chemical specificity to be introduced to these highly sensitive optical sensors, with examples of both copper and sodium selective sensors presented

Low-energy collision-induced dissociation-tandem mass spectrometry (CIDMS/ MS) is a well-established approach for identifying pharmaceutical drug metabolites. The technique fulfils many necessary requirements for this task, such as a low limit of detection, simple interfacing to chromatographic techniques, capability of fast analyses and automation, and high sensitivity, selectivity and accuracy. However, one of the main limitations of low-energy CID-MS/MS is that unambiguous assignment of the site of metabolism is often not possible, particularly for oxidised metabolites. Further, data interpretation can be time-consuming, thus producing a bottleneck to high-throughput analyses. The aim of the presented study was to identify structurally dependent dissociation pathways using low-energy CID-MS/MS that could facilitate rapid and definitive assignment of the sites of metabolism of new chemical entities. Chapter 4 details a specific loss of 50 m/z units in a model S-oxide that arises due to an ortho-effect. This loss could be used to definitively assign the site of oxidation and discriminate between multiple sulfur atoms in a parent compound. The 50 m/z unit loss was also shown to be a two-step process involving sequential radical losses; a rare observation for even-electron precursor ions under low-energy CID conditions. Chapter 5 discusses the experimental investigation of two unexpected rearrangements during the dissociation of a model S-oxide that could prevent correct assignment of the site of metabolism. Chapter 6 presents a rapid and definitive approach to the characterisation of dialkyl tertiary amine-N-oxides. The work also elucidated generic dissociation behaviour under low-energy CID conditions. Finally, chapter 7 considers an observation of site-specific intra-ionic hydrogen/deuterium exchange in the gas phase. Seven sets of compounds were analysed to investigate the substructures that facilitate the exchange. The work demonstrates a method by which a deuterium label can be inserted into the carbon skeleton of a small molecule without having to synthetically produce the compound, which could be useful in performing timely and cost-effective structural elucidation studies. In summary, the presented study provides two potentially useful approaches for the rapid and definitive identification of oxidised metabolites, as well as increasing the body of knowledge relating to ion-chemistry under low-energy CID conditions.

Recently, a novel diffractive-based encoded system has been developed for various multiplexed suspension biological assays. These microparticles, which are manufactured using photolithography of a commercial epoxy-based negative photoresist (SU-8), contain micrometre-sized diffractive elements and can encode millions of unique codes. In this thesis, the preparation and surface modification of different diffractive microparticles; the attachment of a range of biological molecules (e.g. proteins and peptides) onto the functionalised surfaces; and different on-bead analytical techniques for surface characterisation are described. From a thermodynamic study of a multiplexed immunoassay for immunoglobulins (Ig, MW ~150 kDa), the immobilised probe molecules exhibit high affinity (Kd = 9 ± 3 nM) and excellent specificity (S/N >36:1) for the target analytes. The suspension assay resembles solution-like reaction kinetics allowing detection of multiple target proteins in <20 min. The encoded microparticles can also be used for quantifying small proteins, such as cytokines (MW ~20 kDa). In a particle-based sandwich suspension immunoassay, human tumour necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6) are detected and compared with conventional enzyme-linked immunosorbent assays (ELISA). Correlation coefficients (R2) for the two cytokines are found to be >0.96. Intra-assay variability (%CV) is determined to be <25%. The sensitivity of the multiplexed immunoassay, expressed as Lowest Detection Limit (LDL), is found to be 379 fM and 1.47 pM for TNF-α and IL-6 respectively, and are comparable to the corresponding ELISAs as demonstrated by the suppliers

Tributyltin compounds (TBT) are highly toxic pollutants, mainly introduced to the environment as a marine antifouling agent. The main aim of this work was to evaluate the present methods for the measurement of TBT and its breakdown products dibutyltin and monobutyltin in environmental sediments and waters and to improve upon their measurement. For the analysis of sediments, a triple hexane/acetic acid extraction was employed of tropolone complexes of the organotin compounds. Grignard reagent derivatization and measurements by gas chromatography with pulsed flame photometric detection were then employed. The TBT detection limit of 5 μg Sn/ kg in sediment was below the UK environmental quality target (EQS) value for TBT in sediment (1-2 mg Sn/kg). A pilot investigation was carried out on a small dockyard in Southampton to evaluate if the total amount of tin could be used to predict the presence of TBT. Due to different sources of tin contamination in the studied area no clear overall correlation of TBT with total tin was found. As part of the investigation into the determination of butyltin in sediment, the extraction of TBT from paint particles deposited in sediment during boat refurbishment and the removal of sulphur interferences were investigated. For the extraction of TBT in paint, a pre-treatment procedure was developed based on pre-treatment with dichloromethane (DCM). This treatment improved the extraction of TBT from the paint, but TBT losses can occur during DCM removal by evaporation. Sulphur interferences were successfully removed from the sediment extract by improving the clean-up procedure. This procedure was based on treatment of the hexane extract with activated copper and then passing the hexane extract through a C18 solid phase extraction column. For the determination of butyltins in water a doubly functionalized mesoporous silica was synthesized and used to extract butyltin compounds from water based on a solid phase dispersion technique. Butyltin chlorides were collected from the water on the surface of the HOC18-nanoscavenger, hexylated using a Grignard reagent and quantified by GC-PFPD. Another approach was based on ethylation of tributylin chloride using NaEt4B followed by extraction of the ethylated species on the HOC18-nanoscavenger. TBT detection limits of 1.5 and 3 ng Sn/ L were achieved using the Grignard and NaEt4B approaches respectively and were regarded satisfactory, as they were below or near to the UK EQS for water ( 2 ng/ L). The Grignard approach was more efficient than the NaEt4B approach, but the latter was more precise.

Structural characterisation of impurities from synthetic pathways of drugs is an important process in pharmaceutical development. Dissociation pathways of the impurities can vary between different classes of compounds, often resulting in a challenging and a time-consuming process of data interpretation. A detailed understanding of the specific structural features of the fragmentation behaviour of impurity gas-phase ions affords faster characterisation of the unknown sub-structures. Establishing electrospray ionisation-tandem mass spectrometry (ESI-MS/MS) fragmentation rules, based on structure specific and common fragmentation patterns, can improve the process as a screening method in the R&D of new drugs. This project is focused on understanding dissociation pathways of protonated quinazolines using tandem mass spectrometry. Different ionisation techniques and mass analysers were used to allow comparison studies, which may help to define characteristic fragmentation processes of protonated quinazolines. It was found that the choice of mass spectrometer influences the dissociation pathways of protonated quinazolines to some extent, but it is the structure of the molecule that predominantly controls the fragmentation behaviour. Additionally, Density Functional Theory (DFT) calculations have been performed to investigate stabilities of protonated molecules and their product ions to improve the prediction of MS/MS data. It was found that specific forms of product ions and their probability of formation correlate to experimental data acquired using quadrupole-ion trap mass spectrometry (QIT MS) within 10 % difference in intensity. The approach of DFT-MS/MS may help interpretation of MS/MS data by indicating the favoured protonation sites and proposing most probable forms of product ions. It is suggested that the product ion mass spectrum is most probably a combination of individual product ion mass spectra formed from the heterogeneous population of singly protonated molecules; i.e. protonation does not have to occur on the most basic atom in the molecule, but it can be distributed on a number of most probable sites of protonation. In addition, the position of the charge does not have to be fixed and may transfer to a different heteroatom in the molecule prior the fragmentation. These observations offer the possibility to partially assign structures to isomeric molecules using MS/MS and improve structural identification of quinazoline ions.

Capillary electrophoresis is a generic term used to describe separation techniques employing high voltages. In its simplest form, capillary zone electrophoresis (CZE), separations are based on the differential migration of charged analytes under the influence of a high electric field. CZE offers several advantages over other separation techniques, such as high performance liquid chromatography (HPLC). These include higher separation efficiency, enhanced resolution and reduced analysis time. In addition, small injection volumes (nanolitres cf. microlitres for HPLC) and low solvent consumption make CZE an attractive alternative to HPLC. Unfortunately, CZE is not amenable to neutral species, therefore alternative electroseparation methods are employed for neutrals, e.g. capillary electrochromatography (CEC) and micellar electrokinetic chromatography (MEKC), so therefore CZE can be treated as a complementary technique to HPLC.Mass spectrometry (MS) has previously been demonstrated to be a sensitive, selective and near-universal detector. Analytes must be ionised in order to be detected; thus, CZE (which also requires ions) seems an ideal separation technique for combining with MS.CZE/MS interfacing would seem problematic; the linear flow velocity through the capillary is significantly less than that required by appropriate MS ionisation sources (e.g. continuous-flow fast atom bombardment and electrospray). In addition, it is necessary to provide a ground for the separation voltage within the interface. However, interfacing of CZE and MS was first reported in 1987. Since then three distinct interface designs have been developed, co-axial sheath flow, liquid junction and the use of a low flow electrospray (nanospray) interface. Co-axial sheath flow and liquid junction methods serve to increase the overall flow rate of CZE to a suitable level for MS, whereas nanospray is a low flow ionisation technique that accepts similar flow rates to those provided by CZE.The work presented in this thesis details the off-line development of a CZE separation of a pharmaceutical product (cimetidine) and related impurities. The separation was then transferred to mass spectral detection on a commercial triple quadrupole MS instrument employing home-built co-axial sheath flow (electrospray) and nanospray interfaces and the data obtained evaluated. The separation was subsequently transferred to an orthogonal acceleration time-of-flight MS (oa-ToF) for the exact mass determination of the narrow electrophoretic peaks. The feasibility of hydrogen/deuterium exchange via the sheath liquid for CZE/MS has been investigated using model pharmaceutical compounds and preliminary work is presented. An application of CZE/MS for the separation of nicotine and ten of its metabolites has been developed. This method could be further developed into a quantitative assay for nicotine metabolites in biological fluids and suggestions for future work in this area are made.