<p>Packed capillary liquid chromatography in combination with ultraviolet and mass spectrometric (MS) detection was explored as an analytical tool for drug analysis. The focus was put on column and sample preparation techniques as well as on fundamental aspects and development of chromatographic separations. Both octadecylbonded (C₁₈) silica and porous graphitic carbon (PGC) was used as stationary phases.</p><p>Supercritical carbon dioxide was used as the packing carrier to pack silica based C₁₈ particles in 0.2 mm internal diameter fused silica capillaries. A factorial design was used to examine the influence of selected factors on packing performance. The model obtained indicated that the best packing conditions would include the use of a pressure ramp, a high final pressure and a long restrictor.</p><p>The retention behaviour of sulphated heparin and chondroitin disaccharides of different charge levels was studied on PGC capillary columns. It was found that the retention was strongly dependent on the choice of buffer and number of sulphate groups on the disaccharides. An increase in retention was observed when the temperature or the concentration of the organic modifier was increased.</p><p>A packed capillary PGC column was also used to separate the polar drug L-DOPA and four of its metabolites in plasma. The mobile phase contained no ion-pairing agents and relatively high concentrations of organic modifier, which makes it suitable for e.g. MS detection.</p><p>A method was developed to determine the free concentration of the drug tolterodine at pM-nM levels in microliter plasma volumes. Ultrafiltration was used as the sample preparation method. For the analyses, packed capillary C₁₈ columns in a column-switching system coupled to MS detection was used.</p><p>Finally, the two sample preparation methods ultrafiltration and microdialysis were compared with regard to the determination of the free concentration of ropivacaine in plasma. Both methods gave a free fraction of 6 %.</p>

<p>Liquid chromatography-mass spectrometry (LC-MS) has become an important analytical on-line technique, capable of producing large amounts of data with high selectivity and sensitivity. Optimal use of the sophisticated instrumentation can be attained if the analytical chemists are guided to perform the proper experiments and to extract the useful information from the acquired data. In this thesis, strategies and methods concerning these two issues are presented.</p><p>LC-MS method development will benefit from fundamental understanding of the processes involved. An experimental procedure was designed to determine the coefficients in a model for the electrospray process. By relating these coefficients to the experimental conditions, the influence on signal level and sensitivity for presence of matrix compounds was studied.</p><p>For the optimization of LC-MS methods, strategies based on empirical modelling were worked out. Comparisons were made between artificial neural network (ANN) modelling and linear modelling tools, and a genetic algorithm was implemented to explore the ANN models.</p><p>Visual interpretation and multivariate analysis of LC-MS data is hampered by background signals and noise, and a digital filter for background suppression and signal-to-noise improvement was developed. It is also important to indicate the presence of overlapping peaks, and a strategy for the assessment of peak purity was therefore worked out. These methods and several established methods were implemented in an add-on program (LC-MS Toolbox 1.0) for information extraction of LC-MS data.</p><p>Ultimately, the data produced with LC-MS can be separated into the mass spectra, the elution profiles and the concentrations of the analytes, <i>e.g.</i> with PARAFAC modelling. The trilinear data structure assumed may, however, be distorted by variations in the LC conditions causing retention time shifts. An improved algorithm for time warping that can compensate for some of these deviations was worked out, and its performance as a pre-processing tool for PARAFAC was examined.</p>

A technique to alter the morphology of the inner surface of fused silica capillaries has been developed. The internal surface area is enlarged by means of nano-wires of silica, which are grown from the capillary walls. The growth is initiated by the decomposition of the etchant precursor 2-chloro-1,1,2–trifluoroethylmethyl ether at elevated temperature and pressure. It is suggested that the formation of the nano-wires is a process where hydrogen fluoride is continuously consumed and re-liberated. The amorphous bulk silica wall is dissolved, vaporized and finally condensed, yielding a directional re-formation of silica into nano-wire structures. The unidirectional growth of the nano-wires seems to follow the well-known vapor-liquid-solid (VLS) mechanism since characteristic attributes of the VLS mechanism can be observed in the modified capillaries, such as spherical particles terminating each nano-wire. An alternative procedure was developed based on non-isothermal etching which enabled nano-wire outgrowth in fused silica capillaries with internal diameters exceeding 5 µm. The etched and modified capillaries are expected to be suitable for fluidic applications where a higher surface-to-volume ratio is beneficial, such as open tubular liquid chromatography as well as solid-phase micro-reactors and catalysis including enzymatic reactions. The last part of the thesis describes new techniques developed for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. A set of novel matrices based on polymers/oligomers of benzodioxins and thiophenes has been introduced. Using this approach, which has been given the name Polymer-Assisted Laser Desorption/Ionization (PALDI), the low m/z-range of the mass spectrum, from 180 to 1.000 Da, could be used without the abundant chemical noise which normally disturbs such MALDI-MS spectra. Some of the PALDI matrices also showed excellent behavior in the analysis of low molecular weight polymers. A methodology based on non-linear regression of cumulative frequency distributions in polymers has been developed to compare and evaluate different matrix/polymer/cation agent sample combinations for MALDI and PALDl-MS analyses of low molecular weight polymers.

In this thesis the isolation, synthesis and biological evaluation of natural defense compounds against herbivores or oxidative stress is discussed. The first part concerns the metabolites of platyphylloside ((5S)-5-hydroxy-1,7-bis-(4-hydroxyphenyl)-3-heptanone-5-O-β-D-glucopyranoside), a phenolic glucoside found in birch (Betula pendula) that possess digestibility inhibiting activity in herbivores. The structure-activity relationship of platyphylloside analogues were investigated regarding to stereochemistry and substitution pattern on the aromatic rings. The metabolites formed in vitro in rumen fluid were synthesized and the active metabolite determined as (R)-centrolobol (1,7-bis-(4-hydroxyphenyl)-3-heptanol). Treatment of mice and rats with rac-centrolobol did not effect either food intake or body weight. Effect of platyphylloside in moose was also investigated, and the results indicate that there was an in vivo digestibility reducing activity. The second part concerns naturally occurring antioxidants. Avenanthramides is a class of phenolic antioxidants found in oat (Avena sativa). Avenanthramides derived from either anthranilic acid or 5-hydroxyanthranilic acid were evaluated for their antioxidative capacity and quantified in oat extracts. Avenanthramides derived from 5-hydroxyanthranilic acid possessed higher activity than those from anthranilic acid. The order of reactivity depending on substitution pattern on the phenolic moiety was found to be 4-hydroxy &lt; 4-hydroxy-3-methoxy &lt; 3,5-dimethoxy-4-hydroxy and 3,4-dihydroxy. A synthesis towards antioxidative compounds such as 4-deoxycarbazomycin was developed. The third part concerns the isolation of compounds from Lodgepole pine (Pinus contorta) with antifeedant activity against pine weevil (Hylobius abietis). Two compounds possessing high activity were isolated and identified.

Palladium-promoted reactions have been employed for the synthesis of compounds labelled with 11C (t½ = 20.3 min). The precursor [11C]methyl iodide was used in palladium-promoted cross-coupling reactions with organostannanes. With this method, large molecules with several functional groups, that is prostacyclin analogues, have been synthesised in up to 54 % decay-corrected radiochemical yield, calculated from [11C]methyl iodide. However, since this method did not afford reproducible yields, a second method where copper(I) was used as a co-catalyst with palladium, was developed. In the second method, a lower reaction temperature could be used and more reproducible yields were obtained. Employing this method, a prostaglandin analogue was synthesised in 34 % decay-corrected radiochemical yield calculated from [11C]methyl iodide. The total synthesis time was 30 min and the radiochemical purity was higher than 95 %. The specific radioactivity of the compounds obtained with these two methods was approximately 100 GBq/μmol. 11C-Labelled aliphatic and aromatic alkenes were synthesised from [11C]methyl iodide in a Wittig olefination reaction using a published method. The 11C-labelled alkenes were reacted with five aromatic halidein Heck coupling reactions, producing five [11C]stilbene analogues in 34-40 % decay-corrected radiochemical yield. The radiochemical purity was higher than 95 % and the total synthesis timwas 40 min. 11C-Labelled alkenes were also synthesised from 11C-labelled aldehydes. The 11C-labelled aldehydes were obtained from [11C]carbon monoxide in a palladium-mediated formylation of aryl iodides in 51-87 % radiochemical yield, determined by analytical LC and corrected for trappinefficiency. A range of palladium catalysts and hydride reagents were investigated. The labelled aldehydes were used in a subsequent Wittig olefination reaction where various Wittig salts were employed tsynthesise a variety of alkenes. The radiochemical yields were 30-76 %, determined by analytical LC.

Methods for liquid chromatography-mass spectrometry (LC/MS) with electrospray ionization (ESI) have been developed for the determination of specific radioactivity and for metabolic studies of radiolabelled compounds used in positron emission tomography (PET). These compounds often provide an analytical challenge mainly due to their low concentrations in complex sample matrices. The effect on sensitivity using different mobile phase additives, such as trifluoroacetic acid and formic acid, was investigated. The ESI-MS response shows higher stability and sensitivity when volatile additives are used. For reversed phase ion-pair chromatography separations, however, non-volatile counter-ions are used that destabilize the detector response and reduce the sensitivity. A method was therefore developed for on-line removal of the ion-pairing reagents prior to detection. Packed capillary columns and on-column focusing were used to improve mass sensitivity when analysing limited sample amounts. A commercial interface was modified to assist electrospray ionization at the low flow-rates (1 μl/min) required by columns with an inner diameter of 200 µm. LC-MS methods were developed for determination of specific radioactivity of compounds labelled with short-lived radionuclides (i.e. 11C with T½=20.3 min and 76Br T½=16.2 h). In comparison with UV absorption detection, ESI-MS showed equal or improved sensitivity for all compounds investigated. The sensitivity of the developed methods allowed for detection of the radiolabelled isotope directly by mass spectrometry. A packed capillary LC/MS method was developed for determination of raclopride in plasma samples taken from patients during PET studies after intravenous injection of nanomolar doses. The validated assay exhibited satisfactory accuracy and precision over the concentration range 0.2-15 nM.

In the first part, the preparation and properties of chalcogen-containing vitamin E analogues are described. The sulfur compound 3,3,4,6,7-pentamethyl-2,3-dihydrobenzo[b]thiophene-5-ol was prepared by two different routes using ionic and radical chemistry. Interesting rearrangements were observed in the two synthetic pathways. A new methodology for the synthesis of dihydroselenophene and dihydrotellurophene derivatives is described. In the preparation of the vitamin E analogues 2,3-dihydrobenzo[b]selenophene-5-ol and 2,3-dihydrobenzo[b]tellurophene-5-ol a tellurium-mediated tandem SRN1/SHi sequence was suggested to be operative. 2,3-Dihydrobenzo[b]thiophene-5-ol and the vitamin E-like selenide 2-methyl-2-(4,8,12-trimethyl-tridecyl)-selenochroman-6-ol were prepared via intramolecular homolytic substitution at sulfur and selenium, respectively. The first rate constant for intramolecular homolytic substitution at tellurium is also reported (5x108 s-1 at 25 °C). The antioxidant profile for 2,3-dihydrobenzo[b]furan-5-ol and its 1-thio, 1-seleno, and 1-telluro analogues is described. By means of pulse radiolysis, it was shown that the one-electron reduction potentials (ArO·/ArO-) were independent of the chalcogen (0.49-0.52 V vs NHE). The O-H bond dissociation enthalpies for the compounds were also estimated to be similar (336-340 kJ mol-1). The pKa values and the oxidation potentials were also determined for these compounds. For some compounds the rate of hydrogen atom donation to tert-butoxyl radicals was determined by means of laser flash photolysis. Using a two-phase lipid peroxidation model, it was demonstrated that the selenium and tellurium analogues could be regenerated in the presence of a stoichiometric amount of a reducing agent. The organotellurium analogue also acted as a good glutathione-peroxidase mimic and as a potent inhibitor of lipid peroxidation in liver microsomes. In the second part of the thesis the stabilizing capacity of bis[4-(dimethylamino)phenyl]telluride was investigated in the thermoplastic elastomer PACREL®. It was demonstrated that the addition of 0.17-0.50 % of the telluride significantly improved the tensile strength and elongation at break of the polymer. Chemiluminescence measurements showed that the organotellurium compound prolonged the induction period of thermo-oxidation and reduced the total luminescence intensity of the material.

This work consists of mainly two parts. The first part deals with the sintering behaviour and the microstructural stability of SrFe1-xCrxO3-δ, and the second with transport properties of membranes of the same compositions. The most important experimental tools have been dilatometry and oxygen permeability measurements. Supplementary tools were x-ray diffraction analysis (XRD), scanning electron microscope (SEM) and particle size distribution analysis.

Solid oxide fuel cells and oxygen permeable membranes have received considerable attention during the last decade due to the increasing demand for electrical energy and easily transportable fuels combined with the requirement of low emission of CO2. This work concentrates on the stability of ceramic interfaces in general, and more specifically to heterophase solid state interfaces related to solid oxide fuel cells and oxygen permeable membranes. Reaction mechanisms are discussed and requirements and properties of suitable materials are determined. This thesis consists of three parts: 1) Structure of Ca-substituted lanthanum manganite (Paper I), 2) Reactions between cathode and electrolyte for SOFC applications (Papers II-IV) and 3) Chemical and mechanical aspects of sealing dense oxygen permeable membranes (Papers V and VI).

Packed capillary liquid chromatography in combination with ultraviolet and mass spectrometric (MS) detection was explored as an analytical tool for drug analysis. The focus was put on column and sample preparation techniques as well as on fundamental aspects and development of chromatographic separations. Both octadecylbonded (C18) silica and porous graphitic carbon (PGC) was used as stationary phases. Supercritical carbon dioxide was used as the packing carrier to pack silica based C18 particles in 0.2 mm internal diameter fused silica capillaries. A factorial design was used to examine the influence of selected factors on packing performance. The model obtained indicated that the best packing conditions would include the use of a pressure ramp, a high final pressure and a long restrictor. The retention behaviour of sulphated heparin and chondroitin disaccharides of different charge levels was studied on PGC capillary columns. It was found that the retention was strongly dependent on the choice of buffer and number of sulphate groups on the disaccharides. An increase in retention was observed when the temperature or the concentration of the organic modifier was increased. A packed capillary PGC column was also used to separate the polar drug L-DOPA and four of its metabolites in plasma. The mobile phase contained no ion-pairing agents and relatively high concentrations of organic modifier, which makes it suitable for e.g. MS detection. A method was developed to determine the free concentration of the drug tolterodine at pM-nM levels in microliter plasma volumes. Ultrafiltration was used as the sample preparation method. For the analyses, packed capillary C18 columns in a column-switching system coupled to MS detection was used. Finally, the two sample preparation methods ultrafiltration and microdialysis were compared with regard to the determination of the free concentration of ropivacaine in plasma. Both methods gave a free fraction of 6 %.