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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
261

Analysis of partially carbonised residues from the Chiseldon Cauldrons by gas chromatography-mass spectrometry and gas chromatography-combustion-isotope ratio mass spectrometry

Steele, Valerie J. January 2017 (has links)
No / During the micro-excavation of the cauldrons, residues were identified which appeared different from the surrounding soil and metal corrosion products. Thirty-seven of these residues from nine cauldrons and two significant fragments of incomplete cauldrons were analysed by gas chromatography-mass spectrometry (GC-MS) along with two samples of soil from the micro-excavation for comparison. The aim of the analysis was to determine whether these residues contained any organic material related to the use of the cauldrons, specifically lipids (fats, waxes, resins etc.) from the preparation of food or drink. Two of the samples from the cauldrons were also sent for compound specific carbon stable isotope analysis by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) to give a more precise identification of the residues.
262

Application of polychlorinated biphenyl signatures for environmental fingerprinting

Megson, David Peter January 2014 (has links)
Polychlorinated Biphenyls (PCBs) are a group of 209 ‘man-made’ chlorinated organic compounds that were widely used in the 20th century for a variety of industrial uses. PCBs were first commercially produced in the 1929 and were manufactured until the 1980s when their use was phased out due to environmental and human health risks. However, due to their widespread use and persistence they are ubiquitous in the environment and remain a contaminant of concern. The structural properties that determine the persistence of PCBs in humans were therefore elucidated by statistical analysis of data from the National Health and Nutrition Examination Survey (NHANES). PCBs with chlorine bonding in the 2,5-and 2,3,6- positions (and 2- in di- and tri-chlorinated congeners) were rapidly biotransformed and so can be classed as episodic congeners whereas PCBs with chlorine bonding in the 2,3,4-, 2,4,5-, 3,4,5-, and 2,3,4,5- positions were more resistant to biotransformation and can therefore be classed as steady state congeners. A fundamental requirement of using PCB signatures for environmental fingerprinting is an effective analytical method capable of producing high resolution signatures from biological samples. An extraction and clean-up method was developed that was successfully applied to different biological matrices (blood and tissues). A two dimensional gas chromatography with time of flight mass spectrometry (GCxGC-ToFMS) method was designed and optimised to provide a congener specific method capable of identifying 200 out of the 209 PCBs, with detection limits in human serum in the range of 1 to 10 ng g-1 lipid. The extraction and detection methods were used to determine the source of PCB contamination and age date exposure in workers at a transformer dismantling plant. A total of 84 different PCB congeners were identified in the sera of 30 workers with concentrations of the 7 indicator PCBs ranging from 1.2 - 39 μg g-1 lipid. Analysis of PCB signatures was able to distinguish recent from prolonged exposure and also identified an additional source of inhalation exposure in a subgroup of workers. Analysis of 12 different tissue types obtained from the common guillemot (Uria aalge) suggested a high degree of perpetuation between the PCB signature in different tissue types. This shows that comparative assessments can be undertaken between animals using different tissue types and that small (1 g) samples of blood can be used as a non-lethal sampling technique. The regional provenance of 25 wrecked Leach’s storm petrels (Oceanodroma leucorhoa) was also determined using PCB signatures. Results from GCxGC-ToFMS analysis revealed distinctively different PCB signatures in birds from Canada and Europe. The findings reported in this thesis enhance our understanding of PCB signatures in the environment and show how they can be used effectively to age date and identify the source of exposure in humans and animals.
263

The use of multidimensional GC techniques for the analysis of complex petrochemical products

Van der Westhuizen, Rina 12 1900 (has links)
90 leaves on CD format, preliminary i-ix pages and numbered pages 1-81. Includes bibliography, list of figures in color to pdf format (OCR). / Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: The composition of petrochemical products obtained from Fischer Tropsch (FT) technologies is of the highest complexity possible and may contain thousands of components. Chemicals produced from FT feedstocks often contain trace level contaminants that can poison catalysts or that affect product performance in down-line processes. Single dimension GC analysis of these mixtures provides incomplete information because of lack of separation power. This study evaluates the separation power of heart-cut GC-GC, comprehensive GCxGC and sequential GC-GC for three selected challenging petrochemical applications. The fundamental theoretical aspects of the techniques are discussed. Oxygenates are removed as far as possible in C10 – C13 alkylation feedstocks, used in the production of linear alkyl benzenes, because the oxygenates may have deactivating effects on some expensive alkylation catalysts. Residual oxygenates may still be present and can consist of hundreds of components. Detection of individual components at ng/g levels is required. Heart-cut GC-GC is used to illustrate the separation and enrichment power for oxygenates in an alkylation feedstock. The stationary phase in the first dimension column was selected to provide separation of the oxygenates from the hydrocarbons in a relatively narrow window. The oxygenate fraction is then enriched by repeated injections and collection on the cryotrap. After sufficient enrichment, the trap is heated and the oxygenates are analysed on the second dimension column. Comprehensive GCxGC and Sequential GC-GC are compared for the separation and analysis of the oxygenated chemical component classes in the alkylation feedstock, before removal of oxygenates. Cyclic alcohols can occur in detergent alcohols produced from FT feedstocks. These cyclics are regarded as impurities because they affect the physical properties of the detergents. The cyclic and noncyclic alcohols in a narrow C12 – C13 detergent alcohol distillation cut have similar boiling points and polarities, and separation of individual components is thus difficult to achieve. Comprehensive GCxGC and sequential GC-GC are evaluated for the separation of the alcohol component classes. The study shows that both approaches provide component class separation but the high resolving power of the second column and the optimal chromatographic operating conditions of sequential GC-GC provide better separation of the individual components. The study illustrates the immense power of the three multidimensional GC techniques namely heart-cut GC-GC, comprehensive GCxGC and sequential GC-GC. The three multidimensional GC techniques each have their own advantages, disadvantages and unique applications and should be used as complementary rather than as competitive analytical tools. / AFRIKAANSE OPSOMMING: Fischer Tropsch (FT) petrochemiese produkte is van baie hoë kompleksiteit en kan uit duisende komponente bestaan. Chemikalië afkomstig van dié voerstrome bevat soms spoorhoeveelhede onsuiwerhede wat deaktiverend op kataliste kan inwerk of wat die werkverrrigting van finale produkte kan beïnvloed. Enkeldimensie GC analises van die komplekse mengsels is meesal onakkuraat as gevolg van geweldige piekoorvleueling. Die studie evalueer die skeidingsvermoë van drie multidimensionele tegnieke, Heart-cut GC-GC, Comprehensive GCxGC en Sequential GC-GC vir geselekteerde petrochemiese toepassings. Die fundamentele teoretiese aspekte van die tegnieke word bespreek en drie analitiese toepassings word beskryf. Oksigenate word so ver moontlik verwyder uit C10 – C13 paraffien-voerstrome, wat gebruik word in die vervaardiging van liniêre alkielbenzene, aangesien dit deaktiverend kan inwerk op alkileringskataliste. Die oorblywende oksigenate kan uit honderde komponente bestaan sodat analise van individuele komponente tot op lae ng/g vlakke nodig is. Heart-cut GC-GC word gebruik om die skeiding en verryking van die oksigenate in die alkileringsvoerstroom te illustreer. Die stationêre fase in die eerste-dimensie kolom is so gekies dat skeiding tussen oksigenate en koolwaterstowwe verkry word. Met herhaalde inspuitings verhoog die oksigenaat-konsentrasie op die cryo val en - na voldoende verryking - word die val verhit en die oksigenate geanaliseer op die tweede dimensie kolom. Die skeiding en analises verkry met Comprehensive GCxGC en Sequential GC-GC word vergelyk vir die chemiese klasse-skeiding van die alkileringsvoer (voor verwydering van oksigenate). Sikliese alkohole kan voorkom in detergent-alkohole vervaardig vanaf FT voerstrome. Dit word as onsuiwerhede beskou aangesien dit die fisiese eienskappe van die finale produkte beïnvloed. Die sikliese en nie-sikliese alkohole se kookpunte en polariteite is baie naby aanmekaar sodat skeiding van individuele komponente moeilik verkry word. Comprehensive GCxGC en Sequential GC-GC word evalueer vir die skeiding van die alkohol. Die studie toon aan dat albei die tegnieke skeiding gee van die chemiese komponent-klasse maar dat die hoë-resolusie tweede-dimensie kolom en die optimisering van die experimentele kondisies van die Sequential GC-GC sisteem beter skeiding van individuele komponente gee. Die uitsonderlike skeidingsvermoë van die drie multidimensionele tegnieke, Heart-cut GC-GC, Comprehensive GCxGC en Sequential GC-GC word geïllustreer in die studie. Elke tegniek het sy eie voordele, nadele en unieke toepassings en die drie tegnieke behoort as komplementêre eerder as kompeterende tegnieke gebruik te word.
264

Gaschromatografiese analise van geurstowwe in wyn

Wagener, W. W. D. (Wolfram Wilhelm Dirk) 03 1900 (has links)
Thesis (MSc)--Stellenbosch University, 1965. / ENGLISH ABSTRACT: no abstract available / AFRIKAANSE OPSOMMING: geen opsomming
265

Gaschromatografiese analise vir geurstowwe in wyn

Wenzel, K. W. O. (Klaus Willy Otto) 03 1900 (has links)
Thesis (MSc)--Stellenbosch University, 1966. / ENGLISH ABSTRACT: no abstract available / AFRIKAANSE OPSOMMING: geen opsomming
266

Comprehensive multidimensional gas chromatography for the analysis of Fischer-Tropsch products

Van der Westhuizen, Katriena Elizabet 12 1900 (has links)
Thesis (PhD)--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The analysis of Fischer–Tropsch–derived (FT–derived) synthetic crude and derived products is very challenging because of the highly complex nature of these products. In this study, the use of comprehensive multidimensional gas chromatography (GCxGC) with time-of-flight mass spectrometry (TOF-MS) and flame ionisation detection (FID) was investigated for the analysis of these products and the technique was found to be invaluable for the analysis of these complex mixtures. The compositions of FT synthetic crude, produced at low temperature (LT–FT) and high temperature (HT–FT) processes were compared and the effect that changes in FT reaction temperature has on product formation was investigated. Results for conventional onedimensional GC (1D-GC) and GCxGC were compared. It was found that conventional 1D–GC does not have sufficient peak capacity to separate the thousands of compounds in the HT FT products. GCxGC provides a huge peak capacity of tens-of-thousands to separate highly complex mixtures. Structured chromatograms, where groups of compounds with similar properties are grouped together, aid in peak identification. Moreover, sensitivity at low microgram per milliliter levels is obtained. These attributes enabled accurate analysis of various complex feed and product streams in the FT refinery, and also various final fuel products. The use of GCxGC alone was demonstrated, and also combined with high performance liquid chromatography (HPLC), supercritical fluid chromatography (SFC) and nuclear magnetic resonance (NMR) when even more separation power was needed. HPLC–GCxGC enabled the separation of alkene and cyclic alkane compound classes in oligomerisation products. These compound classes have similar mass spectra, elute in adjacent regions and co–elute even to some extent on the GCxGC contour plot, making differentiation difficult. SFC is a good replacement for HPLC for these applications because it does not use solvents as mobile phases. CO2 is easily evaporated after the separation and does not interfere with the GCxGC separation of the analytes. SFC is also a very good technique to separate the compound classes of alkanes, alkenes, aromatics and oxygenates, and is therefore highly complementary to GCxGC. The combination of GCxGC with NMR data was also found to be very valuable for the identification of branched alkane isomers in LT–FT diesels. GCxGC provides excellent separation of individual compounds but the identification of isomers (except for mono–methyl branching) is difficult because the mass spectra of most of these isomers are similar and not all compounds are in the mass spectral libraries. NMR, on the other hand, is able to distinguish between the individual types of branched isomers but has limited separation power for the complex mixtures. By combining the two techniques, the best of both was obtained. The study found GCxGC to be invaluable for the analysis of the highly complex FT–derived products, while its combination with other techniques such as HPLC, SFC and NMR provided even more separation power. / AFRIKAANSE OPSOMMING: Die hoogs komplekse samestelling van sintetiese ru–olie en afgeleide produkte, afkomstig van Fischer–Tropsch (FT) sintese, bied groot uitdagings aan die analis. Die studie het die gebruik van GCxGC met ’n TOF-MS en FID bestudeer vir die analise van FT produkte en het bevind dat die tegniek van onskatbare waarde is vir die analise van die hoogs komplekse mengsels. Die samestellings van produkte van lae- en hoë-temperatuur FT prossesse is vergelyk en die effek van ’n verhoging in die reaksie–temperatuur op die produk samestelling is ondersoek. Resultate vir 1D–GC and GCxGC is vergelyk en dit was duidelik dat 1D-GC nie naastenby voldoende piekkapasiteit het om al die komponente van die produkte wat tydens die hoëtemperatuur prosses gevorm word, te kan skei nie. Die GCxGC se piekkapasiteit daarteenoor is in die orde van tienduisende wat die skeiding van hoogs komplekse mensels moontlik maak terwyl die tegniek hoogs gestruktureerde kontoerplotte verskaf wat help met identfikasie van komponente. Die tegniek is verder ook baie sensitief en kan komponente op lae μg/mL vlakke waarneem. Hierdie eienskappe het akkurate analise van verskeie FT produkstrome moontlik gemaak. Die kombinasie van GCxGC met HPLC, SFC en KMR het selfs meer skeidingskrag verskaf waar nodig. HPLC–GCxGC het die skeiding van alkene en sikliese alkane moontlik gemaak. Hierdie komponent klasse se massaspektra is feitlik dieselfde en terselfdertyd elueer die twee groepe reg langs mekaar, en oorvleuel soms selfs tot ’n mate, op die GCxGC kontoerplot, sodat dit moeilik is om daartussen te onderskei. SFC is ’n goeie alternatief vir HPLC in meeste toepassings aangesien die tegniek net CO2 gebruik, wat maklik verdamp by kamertemperatuur en nie oplosmiddels gebruik wat se pieke steur met die van die laekookpunt komponente op die GCxGC kontoerplot nie. Skeidings van die komponentgroepe alkane, alkene, aromate en oksigenate is moontlik met SFC en daarom komplimenteer dit die GCxGC skeiding goed aan. Die kombinasie van GCxGC met kern–magnetiese resonansie (KMR) is van waarde gevind om die verskillende tipes vertakkings in ’n lae-temperatuur FT diesel te identifiseer. GCxGC verskaf uitstekende skeiding van individuele komponente maar die identifikasie van die verskilende isomere, behalwe vir die mono-metiel vertakkings, is moeilik aangesien die massaspektra van baie van die komponente soortgelyk is en die komponente nie in die massa spektrum–biblioteke voorkom nie. KMR, aan die ander kant, kan tussen die individuele vertakkings onderskei maar het beperkte skeidingskrag vir komplekse mensels. Deur die twee tegnieke te kombineer is die beste van albei tegnieke bekom. Die studie het bevind dat GCxGC van onskatbare waarde is vir die analise van die komplekse sintetiese FT produkte terwyl die kombinasie met ander tegnieke soos HPLC, SFC and KMR selfs meer skeidingskrag verskaf.
267

The effect of ultraviolet-C treatment on the biochemical composition of beer

Mfa-Mezui, Antoine Aime 03 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: This study describes: · Development of analytical tools to investigate the light struck flavour (LSF) in beer by Gas chromatography mass spectrometry (GCMS) and by liquid chromatography mass spectrometry/mass spectrometry (LCMS/MS). Development of a high performance liquid chromatography (HPLC) method to analyse carbohydrates in beer. · The efficiency a pilot scale ultraviolet (UV-C) system at 254 nm to inactivate spoilage microorganisms spiked in commercial beer. Bacteria test were Lactobacillus brevis, Acetobacter pasteurianus and Saccharomyces cerevisiae · A pilot scale UV treatment of commercial and non-commercial lager beers at UV dosage of 1000 J/L. Following the UV treatment, the correlation between chemical analyses and sensory tests conducted by consumers’ tasters were investigated. · A pilot scale UV treatment of non-commercial beer brewed with reduced hops iso-α-acids (tetrahydro-iso-α-acids) at UV dosage of 1000 J/L. Sensory changes and chemical properties were investigated. · The development and optimisation of an UV light emitting diodes (UV-LED) bench scale apparatus. Chemical and microbiological tests were conducted to investigate the effect of UV-LEDs on beer at 250 nm and 275 nm wavelengths. / AFRIKAANSE OPSOMMING: Hierdie studie beskryf: · Die ontwikkeling van analitiese toerusting om die invloed van lig op die smaakontwikkeling in bier te bestudeer m.b.v gaschromatografie massa spektrometrie (GCMS) en vloeistofchromatografie massa spektrometrie/massa spektrometrie, asook die ontwikkeling van ‘n hoë druk vloeistofchromatografiese metode vir die analise van koolhidrate in bier. · Die doeltreffendheid van ‘n toetsskaal ultraviolet (UV-C) sisteem om die nadelige mikroorganismes waarmee die bier geïnnokuleer was, by 254 nm te inaktiveer.. Toetse is uitgevoer met die volgende bakterieë, Lactobacillus brevis, Acetobacter pasteuriants en Saccharomyces cerevisiae. · ‘n Toetsskaal UV behandeling van kommersiële en nie-kommersiële lager biere by ‘n UV dosering van 1000 J/L. Na UV behandeling is die verwantskap tussen chemiese analises en ‘n reeks sensoriese toetse deur vebruikers proeërs ondersoek.. · ‘n Toetsskaal UV behandeling van ‘n nie-kommersiële bier gebrou met verlaagde hops-iso-α-sure (tetrahidro-iso-α -sure) by UV dosering van 1000 J/L. Sensoriese veranderinge asook chemiese eienskappe is ondersoek. · Die ontwikkeling en optimalisering van ‘n UV-lig emissie diodes bankskaal apparaat. Chemiese en mikrobiologiese toetse is uitgevoer om die effek van UV lig op bier by 250 nm en 275 nm te ondersoek.
268

Fatty acid and lipid profiles in models of neuroinflammation and mood disorders : application of high field NMR, gas chromotography and liquid chromotography-tandem mass spectrometry to investigate the effects of atorvaststin in brain and liver lipids and explore brain lipid changes in the FSL model of depression

Anyakoha, Ngozi Gloria January 2009 (has links)
Lipids are important for the structural and physiological functions of neuronal cell membranes. Alterations in their lipid composition may result in membrane dysfunction and subsequent neuronal deficits that characterise various disorders. This study focused on profiling lipids of aged and LPS-treated rat brain and liver tissue with a view to explore the effect of atorvastatin in neuroinflammation, and examining lipid changes in different areas of rat brain of the Flinders Sensitive Line (FSL) rats, a genetic model of depression. Lipids and other analytes extracted from tissue samples were analysed with proton nuclear magnetic resonance spectroscopy (1H-NMR), gas chromatography (GC) and liquid chromatography-tandem mass spectroscopy (LC/ESI-MS/MS). Changes in the lipid profiles suggested that brain and liver responded differently to ageing and LPS-induced neuroinflammation. In the aged animals, n-3 PUFA were reduced in the brain but were increased in the liver. However, following treatment with LPS, these effects were not observed. Nevertheless, in both models, brain concentration of monounsaturated fatty acids was increased while the liver was able to maintain its monounsaturated fatty acid concentration. Atorvastatin reversed the reduction in n-3 PUFA in the aged brain without reducing brain and liver concentration of cholesterol. These findings further highlight alterations in lipid metabolism in agerelated neuroinflammation and show that the anti-inflammatory actions of atorvastatin may include a modulation of fatty acid metabolism. When studying the FSL model, there were differences in the lipid profile of different brain areas of FSL rats compared to Sprague-Dawley controls. In all brain areas, arachidonic acid was increased in the FSL rats. Docosahexaenoic acid and ether lipids were reduced, while cholesterol and sphingolipids were increased in the hypothalamus of the FSL rats. Furthermore, total diacylglycerophospholipids were reduced in the prefrontal cortex and hypothalamus of the FSL rats. These results show differences in the lipid metabolism of the FSL rat brain and may be suggestive of changes occurring in the brain tissue in depression.
269

Trąšų pramonėje naudojamų korozijos inhibitorių analizė chromatografijos ir masių spektrometrijos metodais / Chromatographic and mass-spectrometric analysis of corrosion inhibitors used in the fertilizer industry

Sirtautas, Ramūnas 10 August 2009 (has links)
Skystosios trąšos yra laikomos, gaminamos ir transportuojamos plieninėse talpose, kurios visiškai surūdytų, jei nebūtų pridedama korozijos inhibitorių. Korozijos inhibitoriai yra sudaryti iš cheminių junginių, kurie apsaugo plieno paviršių formuodami apsauginį sluoksnį. Šis sluoksnis apsaugo plieno paviršių nuo reakcijos su skystųjų trąšų komponentėmis ir taip galima sutaupyti milijonines lėšas, nesant būtinybės keisti ar taisyti plienines talpas. Lietuvoje AB „Achema“ per metus pagamina apie 1 milijoną tonų skystųjų trąšų. Dažniausiai korozijos inhibitorius sudaro riebiosios rūgštys, aminai, paviršiaus aktyvios medžiagos, glikoliai ir kt. Korozijos inhibitoriai plačiai analizuojami dujų ir skysčių chromatografijos - masių spektrometrijos metodais. Šiame darbe bus pristatyti dujų chromatografijos - masių spektrometrijos, efektyviosios skysčių chromatografijos - elektropurkštuvinės jonizacijos - skrydžio laiko masių spektrometrijos ir matrica skatinamos lazeriu sužadinamos - skrydžio laiko masių spektrometrijos metodai komercinių korozijos inhibitorių sudėties nustatymui ir indentifikavimui. Šio darbo tikslas buvo optimizuoti chromatografijos ir masių spektrometrijos metodikas skirtas korozijos inhibitorių analizei ir nustatyti komercinių korozijos inhibitorių kiekybinę ir kokybinę sudėtį. Darbo rezultatai. Ištirti trys skirtingų gamintojų komerciniai korozijos inhibitoriai: Cordon 99, Galoryl Ic 22, Ixonol-5. Dujų chromatografijos - masių spektrometrijos metodu nustatyta... [toliau žr. visą tekstą] / Liquid fertilizers are stored, manufactured, and transported in metallic tanks which can completely corrode if corrosion inhibitor will not be added. Corrosion inhibitors are chemical compounds which protect metallic surface by forming a protection layer. This layer protects metallic surface from reaction with liquid fertilizers compounds and can save millions of dollars, since there are no need to replace or repair the tanks. In Lithuania Achema corporation is producing about 1 million tons of liquid fertilizers in the year. Usual ingredients of corrosion inhibitors are fatty acids, amines, surfactants, glycols etc. Corrosion inhibitors are widely analyzed by gas and liquid chromatographic mass spectrometry methods. In this work will be presented gas chromatography- mass spectrometry, high performance liquid chromatography - electrospray ionization – time-of-flight - mass spectrometry and matrix assisted laser desorption ionization time-of-flight mass spectrometry, methods for commercial corrosion inhibitors determination and identification. The aim of this work is optimize chromatographic and mass spectrometry methods for corrosion inhibitors analysis and determinate quantitative and qualitative composition of commercial corrosion inhibitors. Results. Analyses of corrosion inhibitors: Cordon 99, Galoryl Ic 22, Ixonol-5 from three different manufacturers were performed. The main compound determined in all the corrosion inhibitors samples by gas chromatography mass... [to full text]
270

Laser Desorption Solid Phase Microextraction

Wang, Yan January 2006 (has links)
The use of laser desorption as a sample introduction method for solid phase microextraction (SPME) has been investigated in this research project. Three different types of analytical instruments, mass spectrometry (MS), ion mobility spectrometry (IMS) and gas chromatography (GC) were employed as detectors. The coupling of laser desorption SPME to these three instruments was constructed and described in here. <br /><br /> Solid phase microextraction/surface enhanced laser desorption ionization fibers (SPME/SELDI) were developed and have been coupled to two IMS devices. SPME/SELDI combines sampling, sample preparation and sample introduction with the ionization and desorption of the analytes. Other than being the extraction phase for the SPME fiber, the electro-conductive polymer coatings can facilitate the ionization process without the involvement of a matrix assisted laser desorption/ionization (MALDI) matrix. The performance of the SPME coatings and the experimental parameters for laser desorption SPME were investigated with the SPME/SELDI IMS devices. The new SPME/SELDI-IMS 400B device has a faster data acquisition system and a more powerful data analysis program. The optimum laser operation parameters were 250 <em>&mu;J</em> laser energy and 20 <em>Hz</em> repetition rate. Three new SPME coatings, polypyrrole (PPY), polythiophene (PTH) and polyaniline (PAN) were developed and evaluated by an IMS and a GC. The PPY coating was found to have the best performance and was used in most of the experiments. The characteristics of the PPY and the PTH SPME/SELDI fiber were then assessed with both IMS and MS. Good linearity could be observed between the fiber surface area and the signal intensity, and between the concentration and the signal intensities. <br /><br /> The ionization mechanism of poly(ethylene glycol) 400 (PEG) was studied with the SPME/SELDI-IMS 400B device. It was found that the potassiated ions and sodiated ions were both present in the ion mobility spectra. The results obtained with quadrupole time-of-flight (QTOF) MS confirmed the presence of both potassiated and sodiated ions. This result suggested that cationization is the main ionization process when polymers are directly ionized from the PPY coated silica surface. Four PEGs with different average molecular weights and poly(propylene glycol) 400 were also tested with this SPME/SELDI device. The differences between the ion mobility spectra of these polymers could be used for the fast identification of synthetic polymers. <br /><br /> The SPME/SELDI fibers were then coupled to QTOF MS and hybrid quadrupole linear ion trap (QqLIT) MS, respectively. Improved sensitivity could be achieved with QqLIT MS, as the modified AP MALDI source facilitated the ion transmission. The application of method for analysis of urine sample and the bovine serum albumin (BSA) digest were demonstrated with both PPY and PTH fibers. The LOD for leucine enkephalin in urine was determined to be 40 <em>fmol &mu;L<sup>-1</sup></em> with PTH coated fiber; and the LOD for the BSA digest was 2 <em>fmol &mu;L<sup>-1</sup></em> obtained with both PTH and PPY fibers. <br /><br /> A new multiplexed SPME/AP MALDI plate was designed and evaluated on the same QqLIT MS to improve the throughput, and the performance of this technique. The experimental parameters were optimized to obtain a significant improvement in performance. The incorporation of diluted matrix to the extraction solution improved the absolute signal and S/N ratio by 104X and 32X, respectively. The incorporation of reflection geometry for the laser illumination improved the S/N ratio by more than two orders of magnitude. The fully optimized high throughput SPME/AP MALDI configuration generated detection limit improvements on the order of 1000-7500X those achieved prior to these modifications. This system presents a possible alternative for qualitative proteomics and drug screening. <br /><br /> Laser desorption SPME as a sample introduction method for the fast analysis of non-volatile synthetic polymers was also demonstrated here. The coupling of laser desorption SPME to GC/FID and GC/MS was performed, and the advantage of laser desorption over traditional thermal desorption was demonstrated in this research. Laser desorption PEG 400 was observed more effcient than thermal desorption. Good separation was obtained even with a 1-m or 2-m column. These results demonstrate the potential of laser desorption SPME as a sample introduction method for the fast GC analysis of non-volatile compounds such as synthetic polymers.

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