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Tesi sul tema "Mass spectrometry"
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1
Lemire, Sharon Warford. "Rigorous analytical applications of liquid secondary ion mass spectrometry/mass spectrometry". Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/30026.
Testo completo
2
Dabney, David E. "Analysis of Synthetic Polymers by Mass Spectrometry and Tandem Mass Spectrometry". University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1259021862.
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3
Goodwin, Lee. "Capillary electrophoresis-mass spectrometry and tandem mass spectrometry studies of ionic agrochemicals". Thesis, University of York, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398906.
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4
Shliaha, Pavel Vyacheslavovich. "Investigation of protein abundance and localization by mass spectrometry and ion-mobility spectrometry-mass spectrometry methods". Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708661.
Testo completo
5
Hsi, Kuang-Ying. "Peptide identification of tandem mass spectrometry from quadrupole time-of-flight mass spectrometers". Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p1462246.
Testo completoAbstract (sommario):
Thesis (M.S.)--University of California, San Diego, 2009.Title from first page of PDF file (viewed May 4, 2009). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 45-46).
6
Yuen, Wei Hao. "Ion imaging mass spectrometry". Thesis, University of Oxford, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.564395.
Testo completoAbstract (sommario):
This work investigates the applicability of fast detectors to the technique of microscope-mode imaging mass spectrometry. By ionising analyte from a large area of the sample, and projecting the desorbed ions by the use of ion optics through a time-of-flight mass spectrometer onto a two- dimensional detector, time- (and hence mass-) dependent distributions of ions may be imaged. To date, this method of imaging mass spectrometry has been limited by the ability to image only one mass window of interest per experimental cycle, limiting throughput and processing speed. Thus, the alternative microprobe-mode imaging mass spectrometry is currently the dominant method of analysis, with its superior mass resolution. The application of fast detectors to microscope-mode imaging lifts the restriction of the detection of a single mass window per experimental cycle, potentially decreasing acquisition time by a factor of the number of mass peaks of interest. Additional advantages include the reduction of sample damage by laser ablation, and the potential identification of coincident eo-fragments of different masses originating from the same parent molecule. Theoretical calculations and simulations have been performed confirming the suitability of conventional time-of-flight velocity-mapped ion imaging apparatus for imaging mass spectrometry. Only small modifications to the repeller plate and laser beam path, together with the adjustment of the accelerating potential field, were required to convert the apparatus to a wide (7 mm diameter) field-of-view ion microscope. Factors affecting the mass and spatial resolution were investigated with these theoretical calculations, with theoretical calculations predicting a spatial resolution of about 26μm and m/m of 93. Typical experimental data collected from velocity-mapped ion imaging experiments were collected, and characterised in order to provide specifications for a novel time-stamping detector, the Pixel Imaging Mass Spectrometry detector. From these data, the suitability of thresholding and centroiding on the new detector was determined. Initial experiments using desorptionjionisation on silicon and conventional charge-coupled device cameras confirmed the correct spatial-mapping of the apparatus. Matrix-assisted laser desorptionjionisation techniques (MALDI) were used in experiments to determine the spatial and mass resolutions attainable with the apparatus. Experimental spatial resolutions of 14.4 μm and m/m of 60 were found. The better experimental spatial resolution indicates a higher di- rectionality of initial velocities from MALDI desorption than used in the theoretical predictions, while the poorer mass resolution could be attributed to limitations imposed by the use of the phosphor screen. Proof-of-concept experiments using fast-framing cameras and the new time-stamping detectors confirmed the feasibility of multiple mass acquisition in time-of-flight microscope mode ion imaging. Mass-dependent distributions were acquired of different pigment distributions in each experimental cycle. Finally, spatial-mapped images of coronal mouse brain sections were acquired using both conventional and fast detectors. The apparatus was demonstrated to provide accurate spatial distributions with a wide field-of-view, and multiple mass distributions were acquired with each experimental cycle using the new time-stamping detector.
7
Berezovskaya, Yana. "Investigation of protein-ion interactions by mass spectrometry and ion mobility mass spectrometry". Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/7747.
Testo completoAbstract (sommario):
Protein‐ion interactions play an important role in biological systems. A considerable number of elements (estimated 25 – 30) are essential in higher life forms such as animals and humans, where they are integral part of enzymes involved in plethora of cellular processes. It is difficult to overestimate the importance of thorough understanding of how protein‐ion interplay affects living cell in order to be able to address therapeutic challenges facing humanity. Presented to the reader’s attention is a gas‐phase biophysical analysis of peptides’ and proteins’ interactions with biologically relevant ions (Zn2+ and I–). This investigation provides an insight into conformational changes of peptides and proteins triggered by ions. Mass spectrometry and ion mobility mass spectrometry are used in this work to probe peptide and protein affinities for a range of ions, along with conformational changes that take place as a result of binding. Observation of peptide and protein behaviour in the gas phase can inform the investigator about their behaviour in solution prior to ionisation and transfer from the former into the latter phase. Wherever relevant, the gas‐phase studies are complemented by molecular dynamics simulations and the results are compared to solution phase findings (spectroscopy). Two case studies of protein‐ion interactions are presented in this thesis. Firstly, sequence‐to‐structure relationships in proteins are considered via protein design approach using two synthetic peptide‐based systems. The first system is a synthetic consensus zinc finger sequence (vCP1) that is responsive to zinc: it adopts a zinc finger fold in the presence of Zn2+ by coordinating the metal ion by two cysteines and two histidines. This peptide has been selected as a reference for the zinc‐bound state and a simple model to refine the characterisation method in preparation for analysis of a more sophisticated second system – dual conformational switch. This second system (ZiCop) is designed to adopt either of the two conformations in response to a stimulus: zinc finger or coiled coil. The reversible switch between the two conformational states is controlled by the binding of zinc ion to the peptide. Interactions of both peptide systems with a number of other divalent metal cations (Co2+, Ca2+ and Cu2+) are considered also, and the differences in binding and switching behaviour are discussed. Secondly, protein‐salt interactions are investigated using three proteins (lysozyme, cytochrome c and BPTI) using variable temperature ion mobility mass spectrometry. Ion mobility measurements were carried out on these proteins with helium as the buffer gas at three different drift cell temperatures – ‘ambient’ (300 K), ‘cold’ (260 K) and ‘hot’ (360 K), and their conformational preferences in response to HI binding and temperature are discussed.
8
Liu, Xiumin. "Mass Spectrometry and Tandem Mass Spectrometry Analysis of Polymers and Polymer-Protein Interactions". University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1406838246.
Testo completo
9
Kaleta, Erin. "Applications of mass spectrometry to bacterial diagnostics: Affinity capture matrix assisted laser desorption/ionization mass spectrometry and polymerase chain reaction mass spectrometry". Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/305352.
Testo completoAbstract (sommario):
This dissertation presents the application of mass spectrometry to the detection and characterization of microorganisms based on biomarker identification and DNA analysis. Two major topics are covered: affinity capture mass spectrometry using immunoassay methods and methods involving insertion of membrane receptors into polymerized planar supported lipid bilayers; and the application of mass spectrometry for use in clinical microbiology for the identification of microorganisms causing bloodstream infections.
Affinity capture mass spectrometry on immunoassay-based platforms studied the capture of Protein A from Staphylococcus aureus , demonstrating capture that is both selective and sensitive. Experiments illustrated successful capture from a purified source and cell lysates. Affinity capture using receptors inserted into polymerized lipid bilayers was also performed using GM1 and cholera toxin subunit B, demonstrating the enhanced stability offered by polymerizing the lipid bilayers such that direct ionization could be performed. Detection of protein binding was achieved with mass spectrometry at low molar ratios of receptor, and enzymatic digestion experiments on the protein retained at the surface illustrated the ability to characterize the protein ligand bound, lending support to using this technique for reverse pharmacological applications. Lastly, experiments demonstrated that affinity capture of surface-bound proteins can also be used to extract cells from complex mixture prior to the polymerase chain reaction, illustrating utility as a pre-treatment for detecting microorganisms in blood samples.
Mass spectrometry was applied to detection of microorganisms from blood culture bottles collected from patients with bloodstream infections. Polymerase chain reaction electrospray ionization and whole cell matrix-assisted laser desorption/ionization mass spectrometry were used to characterize hematopathogens. High diagnostic accuracy was demonstrated with respect to culture-based testing and these two platforms were compared considering accuracy in identification, time to result, and cost benefit analysis.
The experiments presented here cover a broad range of detection strategies for identifying proteins and microorganisms. The affinity capture techniques describe the first application of peptide capture and polymerized bilayers for mass spectrometric analysis, and the clinical mass spectrometry work demonstrates validation of two emerging techniques and the first comparative study on both platforms simultaneously. All research presented here demonstrates promise for application of mass spectrometry in diagnostic biology.
10
Sun, Xiaobo. "Forensic Applications of Gas Chromatography/Mass Spectrometry, High Performance Liquid Chromatography--Mass Spectrometry and Desorption Electrospray Ionization Mass Spectrometry with Chemometric Analysis". Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1329517616.
Testo completo
11
Woods, Lucy Ann. "Characterising amyloid assembly using ion mobility spectrometry-mass spectrometry". Thesis, University of Leeds, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.590277.
Testo completoAbstract (sommario):
From small molecules to macromolecules, mass spectrometry has evolved significantly over the past decade, progressing from a tool to identify chemical elements to a powerful technique able to elucidate structural information for large protein complexes. With the interfacing of ion mobility spectrometry to mass spectrometry (IMS-MS), mass spectrometric analyses now occupy an extra dimension, providing unrivalled separation and structural characterisation of lowly-populated species in heterogeneous mixtures. One biological system that has benefitted enormously from such advances is the study of in vitro amyloid formation. The ability of amyloidogenic proteins to assemble into insoluble fibrils is associated with over twenty-five different disease states. Beta-2 microglobulin (β2m) is one such protein able to assemble into amyloid fibrils in vitro, although assembly can only be initiated upon destabilisation of the native structure. Identifying which states initiate fibril formation is challenging. as few techniques are able to separate and characterise such transient species. In addition, recent research has identified a number of small molecule inhibitors of fibrillation and understanding their mechanism of action is a topic of current interest. Here, the power of IMS-MS has been harnessed to achieve the separation and characterisation of monomeric and oligomeric precursors of amyloid fibril formation of the protein β2m. Analysis of oligomeric species populated during fibril formation, in addition to the effects of small molecule inhibitors on oligomer population, has led to the identification of oligomeric species on-pathway to fibril formation. Further investigation into fibrils of different morphologies has also been conducted using IMS and limited proteolysis, Differences in oligomeric populations have been revealed, together with differences in fibril structure. Each of these results highlights how MS can be used to give insights into the mechanism of amyloid formation and highlight the potentials of this approach for screening for potential inhibitors of any assembly reaction.
12
Zhou, Yi. "Microfluidics interfacing to mass spectrometry". College Park, Md. : University of Maryland, 2007. http://hdl.handle.net/1903/7402.
Testo completoAbstract (sommario):
Thesis (Ph. D.) -- University of Maryland, College Park, 2007.Thesis research directed by: Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
13
Testino, Samuel A. Jr. "Optimization strategies in mass spectrometry". Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/26972.
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14
Rostom, Adam A. "Mass spectrometry of protein interactions". Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312385.
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15
Winter, David. "Drug analysis by mass spectrometry". Thesis, University of Canterbury. Chemistry, 1986. http://hdl.handle.net/10092/6560.
Testo completoAbstract (sommario):
1. The pharmacokinetics of morphine have been measured in four patients with renal failure and three healthy volunteers following intramuscular administration of papaveretum. Morphine blood levels were determined using GCMS with specific ion monitoring. The significantly shorter drug elimination half-life found for the patients suggests that renal failure does not impair the elimination of morphine.
2. A CI GCMS assay with specific ion monitoring has been developed for measuring the anti parkinsonian drug benztropine in post-mortem specimens. The assay is potentially more sensitive than a similar assay using electron impact ionisation.
3. The level of atropine in an aqueous extract of Datura stramonium has been measured by GCMS with selected ion monitoring. The results show that such an extract will contain most of the atropine present in the plant material. The levels are such that several medium sized glassfuls will contain sufficient atropine to constitute a dangerous drug dose.
4. A Hewlett-Packard 5982A GCMS has been successfully modified to allow it to be used to record in-beam mass spectra with a commercially available DCI probe. The effectiveness of these modifications is discussed and in-beam mass spectra of some physiologically active compounds are presented.
16
Perkins, John Robert. "Supercritical fluid chromatography/mass spectrometry". Thesis, Cardiff University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375969.
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17
Smith, Derek John. "Femtosecond Laser Mass Spectrometry (FLMS)". Thesis, University of Glasgow, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264149.
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18
Sweet, Steve M. M. "Phosphoprotein analysis by mass spectrometry". Thesis, University of Manchester, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.538385.
Testo completo
19
Cobice, Diego Federico. "Mass spectrometry imaging of steroids". Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/21032.
Testo completoAbstract (sommario):
Glucocorticoids are steroid hormones involved in the stress response, with a well-established role in promoting cardiovascular risk factors including obesity and diabetes. The focus of glucocorticoid research has shifted from understanding control of blood levels, to understanding the factors that control tissue steroid concentrations available for receptor activation; it is disruption of these tissue-specific factors that has emerged as underpinning pathophysiological mechanisms in cardiovascular risk, and revealed potential therapeutic targets. However, the field is hampered by the inability at present to measure concentrations of steroid within individual tissues and indeed within component cell types. This research project explores the potential for steroid measurements using mass spectrometry-based tissue imaging techniques combining matrix assisted laser desorption ionization with on-tissue derivatisation with Girard T and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (OTCD-MALDIFTICRMS). A mass spectrometry imaging (MSI) platform was developed and validated to quantify inert substrate and active product (11-dehydrocorticosterone (11DHC), corticosterone (CORT) respectively) of the glucocorticoid-amplifying enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) in rodent tissues. A novel approach to derivatising keto-steroids in tissue sections using Girard T reagent was developed and validated. Signals were boosted (10⁴ fold) by formation of GirT hydrazones compared to non-derivatised neutral steroids. Active and inert glucocorticoids were detected in a variety of tissues, including adrenal gland and brain; in the latter, highest abundance was found in the cortex and hippocampus. The MSI platform was also applied to human biopsies and murine tissues for the analysis of other ketosterols such as androgens and oxysterols. Proof-of-principle validation that the MSI platform could be used to quantify differences in enzyme activity was carried out by following in vivo manipulation of 11β-HSD1. Regional steroid distribution of both substrate and product were imaged at 150-200μm resolution in mouse brain sections, and the identification confirmed by collision induced dissociation/liquid extraction surface analysis (CID-LESA). To validate the technique, the CORT/11DHC ratios (active/inert) were determined in 11β- HSD1 deficient mice and found to be reduced (KO vs WT; cortex (49 %*); hippocampus (46 %*); amygdala (57 %)). Following pharmacological inhibition by administration of UE2316, drug levels peaked at 1 h in tissue and at this time point, a reduction in CORT/11DHC ratios were also determined, although to a lesser degree than in KO mice, cortex (22%), hippocampus (25 %) and amygdala (33 %). The changes in ratios appeared driven by accumulation of DHC, the enzyme substrate. In brains of mice with 11β-HSD1 deficiency or inhibition, decreases in sub-regional CORT/11DHC ratio were quantified, as well as accumulation of an alternative 11β- HSD1 substrate, 7-ketocholesterol. MSI data correlated well with the standard liquid chromatography tandem mass spectrometry (LC-MS/MS) in whole brain homogenates. Subsequently, the MSI platform was also applied to measure the dynamic turnover of glucocorticoids by 11β-HSD1 in metabolic tissues using stable isotope tracers (Cortisol-D4 (9,11,12,12-D4) (D4F). D4F was detected in plasma, liver and brain after 6 h infusion and after 48 h in adipose. D3F generation was detected at 6 h in plasma and liver; at 24 h in brain specifically in cortex, hippocampus and amygdala; and at 48 h in adipose. The spatial distribution of d3F generation in brain by MSI closely matched enzyme localisation. In liver, an 11β-HSD1-riched tissue, substantial generation of d3F was detected, with a difference in d4F/d3F ratios compared with plasma (ᴧTTRᴧ 0.18± 0.03 (6 h), 0.27± 0.05 (24 h) and 0.38±0.04 (48 h)). A smaller difference in TTR was also detected between plasma and brain (ᴧTTR 0.09 ± 0.03 (24 h), 0.13±0.04 (48 h)), with no detectable regeneration in adipose. After genetic disruption of 11β-HSD1, d3F generation was not detected in plasma or any tissues, suggesting that 11β-HSD1 is the only enzyme carrying out this reaction. After pharmacological inhibition, a similar pattern was seen. The circulating concentration of drug peaked at 2 h and declined towards 4 h, with same pattern in liver and brain. The ᴧTTR ratios 2HPD between plasma and liver (0.27±0.08vs. 0.45± 0.04) and brain (0.11±0.2 vs. 0.19± 0.04) were smaller following drug administration than vehicle, indicating less d3F generation. Extent of enzyme inhibition in liver responded quickly to the declining drug, with ᴧTTR returning to normal by 4 h (0.38± 0.06). ᴧTTR had not normalised 4HPD in brain (0.12±0.02, suggesting buffering of this pool. In adipose, UE2316 was not detected and nor were rates of d3F altered by the drug. Two possible phase I CYP450 metabolites were identified in the brain differing in spatial distribution. In conclusion, MSI with on-tissue derivatisation is a powerful new tool to study the regional variation in abundance of steroids within tissues. We have demonstrated that keto-steroids can be studied by MALDI-MSI by using the chemical derivatisation method developed here and exemplified its utility for measuring pharmacodynamic effects of small molecule inhibitors of 11β-HSD1. This approach offers the prospect of many novel insights into tissue-specific steroid and sterol biology.
20
Salter, Tara La Roche. "Metrology for ambient mass spectrometry". Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/28748/.
Testo completoAbstract (sommario):
Ambient mass spectrometry (AMS) is a new and versatile method for analysing a multitude of different sample types with the benefit of analysis at ambient pressure and the many other advantages that this entails. However, as these techniques are still in their infancy, metrological development of the techniques is essential. This is a critical step before AMS can be used reliably in the application areas in which it has shown great promise. The research in this thesis addresses the development of AMS sources, in particular plasma-assisted desorption-ionisation, PADI. Optimisation and characterisation is fundamental to understanding and developing the technique. Optimisation of PADI is addressed; this includes understanding the effects of different parameters to maximise signal intensities. The power, and temperature, of the plasma is shown to have a significant effect on the fragmentation observed in the mass spectra. This is an important result that is further explored with the use of thermal desorption to aid the analysis of low volatility molecules. The form of the analyte is also an important consideration for analysis by PADI; characteristic ions from powders are easily detected, whereas for thin film samples an analyte vapour pressure of greater than 10-4 Pa is needed. This result provides an indication of the limitations of PADI and what classes of analyte it will be successful at analysing. It is also shown that we can improve signal intensities using a heated sample stage allowing the analytes to be thermally desorbed before being ionised by the plasma. This is an important result for future work, where ambient plasma sources can be implemented as an ionisation source in conjunction with another mechanism, such as thermal or laser desorption, to generate gas-phase ions. A comparison of different ambient methods for personal care products shows the usefulness and also complementarities of PADI with desorption electrospray ionisation, DESI, one of the most established AMS techniques which utilises a different mechanism for desorption and ionisation. This also demonstrates the chemical information that can quickly be gained from these techniques, with minimal sample preparation. DESI is also compared to secondary ion mass spectrometry, SIMS. Vacuum-based techniques such as SIMS are much more established than ambient techniques; it is insightful to understand the advantages that each source can offer, for the analysis of different types of molecule as well as the mass spectral information that can be gained from SIMS and DESI.
21
McClure, Thomas Dale. "Biomedical applications of mass spectrometry". Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185490.
Testo completoAbstract (sommario):
The application of mass spectrometry to verification of the structure of 3-methyluridine (m³U) isolated by HPLC from normal human urine is described. m³U has been used as an internal standard for studies of urinary nucleosides, a practice that is discouraged with the confirmation of m³U as a naturally occurring compound. Mass spectrometry has been used for the identification of 5'-deoxyxanthosine (5'-dX) a novel nucleoside in normal human urine. Initial concern over availability of a reference sample of 5'-dX prompted investigations of the structure/fragmentation relationships of the TMS deratives of 2'-, 3'-, and 5'-deoxynucleosides toward differentiation between the three deoxynucleosides. Results are presented which allow discrimination between the model compounds, deoxyanalogs of adenosine. Subsequent to the deoxynucleoside fragmentation studies, a biosynthetically produced reference sample of 5'-dX became available for direct comparison of mass spectra and chromatographic retention times which, when combined with observations from the deoxynucleoside studies established the structure of 5'-dX. In response to the large number of mass spectra produced from the GC-MS analysis of a TMS derivatized urine sample, computer software has been written to aid in spectral analysis. Examples are shown in which the software uses established fragmentation rules to assign structure to ions in the mass spectrum and suggest modifications in the sugar portion of two urinary nucleosides. The structure/fragmentation relationships of the unique antitumor drug taxol has been studied by EI, CI and FAB mass spectrometry. Information is presented showing characteristic fragmentation of the side-chain and verification of functional groups attached to the taxane ring. Studies have been conducted to determine the relationship between target temperature and matrix and sample lifetime in the source of the mass spectrometer. Results are presented showing that cooling the target permits the use of matrix materials that are too volatile at ambient temperatures thus extending the range of compounds that can be studied by mass spectrometry. A recently constructed four-sector mass spectrometer is described with a detailed discussion of instrumental capabilities. Results of experiments designed to apply these capabilities to the structural analysis of TMS nucleosides using FAB ionization are discussed with an emphasis on the fragmentation unique to 4-sector daughter ion experiments compared with conventional studies and 2-sector daughter ion results.
22
Offei, Felix. "Denoising Tandem Mass Spectrometry Data". Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etd/3218.
Testo completoAbstract (sommario):
Protein identification using tandem mass spectrometry (MS/MS) has proven to be an effective way to identify proteins in a biological sample. An observed spectrum is constructed from the data produced by the tandem mass spectrometer. A protein can be identified if the observed spectrum aligns with the theoretical spectrum. However, data generated by the tandem mass spectrometer are affected by errors thus making protein identification challenging in the field of proteomics. Some of these errors include wrong calibration of the instrument, instrument distortion and noise. In this thesis, we present a pre-processing method, which focuses on the removal of noisy data with the hope of aiding in better identification of proteins. We employ the method of binning to reduce the number of noise peaks in the data without sacrificing the alignment of the observed spectrum with the theoretical spectrum. In some cases, the alignment of the two spectra improved.
23
SPEZZANO, ROBERTO. "Lipids and Mass Spectrometry Application". Doctoral thesis, Università degli Studi di Milano, 2019. http://hdl.handle.net/2434/647470.
Testo completoAbstract (sommario):
During my PhD courses I focused attention on the applications of mass spectrometry in lipidomic studies. I applied mass spectrometry in several experimental models to try to observe differences in selected metabolites affected by a particular pathology.
The first project performed in experimental model of impaird lipogenesis highlighted a cross talk between altered fatty acid synthesis and neuroactive steroid levels.
The second project, mass spectrometry application allows to understand he effect of short-term diabetes on cholesterol metabolism.
In the last project lipidomic pattern was investigated in experimental model of SCA38. Results obtained highlighted as elovl5 mutation affect phospholipids profile.
24
Mohan, Krishnan R. "Fast atom bombardment mass spectrometry and tandem mass spectrometry : conditions for measurement of reproducible spectra". Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/27159.
Testo completo
25
Catron, Brittany Lyn. "Analysis of Protein:RNA Cross-links by Inductively Coupled Plasma Mass Spectrometry and Tandem Mass Spectrometry". University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1337885809.
Testo completo
26
Crnogorac, Goranka. "Analysis of dithiocarbamate fungicide residues by liquid chromatography, mass spectrometry and isotope ratio mass spectrometry". Aachen Shaker, 2008. http://d-nb.info/993691447/04.
Testo completo
27
Zhou, Li. "Enhanced Electrospray Ionization for Mass Spectrometry and Ion Mobility Spectrometry". Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1384.pdf.
Testo completo
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Cunningham, Connell Glish Gary L. "Improved methods of tandem mass spectrometry for proteomics applications in a quadrupole ion trap mass spectrometer". Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2006. http://dc.lib.unc.edu/u?/etd,217.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2006.Title from electronic title page (viewed Oct. 10, 2007). " ... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Chemistry. Chapel Hill 2006." Discipline: Chemistry; Department/School: Chemistry.
29
Perdian, David C. "Direct analysis of samples by mass spectrometry from elements to bio-molecules using laser ablation inductively coupled plasma mass spectrometry and laser desorption/ionization mass spectrometry /". [Ames, Iowa : Iowa State University], 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3369879.
Testo completo
30
Göth, Melanie [Verfasser]. "Investigation of Protein-Ligand Complexes by Native Mass Spectrometry and Ion Mobility-Mass Spectrometry / Melanie Göth". Berlin : Freie Universität Berlin, 2017. http://d-nb.info/1149050594/34.
Testo completo
31
Martin, Nicholas Joseph. "Surface analysis for proteomics via liquid extraction surface analysis mass spectrometry and liquid chromatography mass spectrometry". Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/6493/.
Testo completoAbstract (sommario):
Liquid extraction surface analysis (LESA) is an ambient ionisation technique which allows direct analysis of surfaces coupled with mass spectrometry. LESA mass spectrometry has been used successfully to analyse small molecules, but there are a limited number of examples where the approach has been applied to protein analysis. The work presented here aims to develop novel applications of LESA mass spectrometry of proteins. LESA mass spectrometry was used to analyse intact proteins from polymeric membranes. The rationale for these experiments was the potential application to analyse proteins electroblotted following polyacrylamide gel electrophoresis, i.e. top-down proteomics, and in air monitoring. The subsequent focus was dried blood spot (DBS) analysis. An automated LESA based trypsin digestion protocol was developed and coupled with liquid chromatography tandem mass spectrometry to enable DBS proteomics. i.e., untargeted global protein identification via a bottom-up approach. Approaches for DBS proteomics (in the absence of LESA) were explored further using conventional digestion procedures coupled with protein depletion. LESA was also applied for targeted analysis of proteins from DBS, to determine variants of alpha-1-antitrypsin. Finally, native LESA mass spectrometry was developed to analyse non-covalent complexes from dried surfaces. Native LESA mass spectrometry successfully identified the haemoglobin tetramer directly from DBS.
32
Galezowska, Angelika. "Rapid characterisation of quinazoline drug impurities using electrospray mass spectrometry-mass spectrometry and computational chemistry approaches". Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/300028/.
Testo completoAbstract (sommario):
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.
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John, Gareth David. "Secondary ion mass spectrometry and resonant ionisation mass spectrometry studies of nickel contacts to silicon carbide". Thesis, Swansea University, 2004. https://cronfa.swan.ac.uk/Record/cronfa42495.
Testo completoAbstract (sommario):
Time-of-flight secondary ion mass spectrometry (TOF-SIMS) and resonant ionisation mass spectrometry (RIMS) have been used to perform depth profile analyses on nickel (Ni) contacts to silicon carbide (SiC) to understand the interfacial properties. In particular, as-deposited Schottky contacts and high temperature annealed Ohmic contacts have been characterised. Previous literature had indicated that the chemistry of the interface controlled the electrical properties of the contact. Using the TOF-SIMS system, depth profiles have been performed with the standard duoplasmatron ion source and a newly introduced liquid metal ion gun. Sputtering conditions have been optimised enabling detailed depth profiling of Schottky and Ohmic samples. The data from these samples have indicated a distinct difference between the two contact types. Schottky samples have been shown to have an abrupt interface with any interfacial reaction appearing to be confined to the intimate interface. This region had no significant affect on ion yield. Conversely, the Ohmic samples exhibited an extended Si composition well into the Ni contact layer. Moreover, the ion yield varied substantially throughout the contact layer indicating matrix changes were present as a result of annealing to 1000&C. RIMS studied the variation of Ni atoms sputtered into the Ni ground state (a3F4) and first excited state (a3D3) to determine variation in chemical bonding as a function of depth through the contact. Using a defocused ion beam passing through an aperture, detailed depth profiles were obtained by using two-colour, two-step resonant ionisation scheme. Again, a significant variation exists between the RIMS signals from Ohmic and Schottky samples. The ratio of the excited state to ground state for Ni showed measurable variations indicative of multiple Ni-silicide phases. Models for these interfaces are proposed and support other studies performed on this material system. The success of these techniques is reviewed together with suggestions for experimental development.
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Zoppi, Ugo. "Isobar suppression in accelerator mass spectrometry /". [S.l.] : [s.n.], 1993. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=10373.
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Bundala, Matthew Matus. "Serological immune profiling using mass spectrometry". Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/63765.
Testo completoAbstract (sommario):
The adaptive immune system is a fantastically complex system comprised of specialized cells, organs and molecules. When properly functioning, our adaptive immune system is continually responding to, and protecting us from, a myriad of disease threats ranging from viruses to cancer. Immune dysfunction leaves us vulnerable to pathogens and can result in autoimmune disorders. Despite the adaptive immune system’s central importance in health, efficient immune profiling methods, and in particular approaches capable of functional characterization of adaptive immune responses, are still in their infancy. In this thesis I present a rapid and scalable serological immune profiling protocol based on antibody mediated identification of antigens (AMIDA). Serological antibodies are extracted from serum, covalently bound to magnetic beads, and washed with a panel of antigens. The bound immunoreactive antigens are then eluted, in-gel trypsin digested, and identified by tandem mass spectrometry. I demonstrate the application of this protocol for profiling immune responses of nine patients to a set of bacterial pathogens including Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Salmonella typhimurium. The identified list of antigens includes outer membrane proteins known to cause immune reaction, as well as novel immunogenic proteins. The data allows for characterization of differences in the global antigen reactivity between different patients and identifies individuals having pronounced pathogen recognition. In a small study I show that K. pneumoniae and P. aeruginosa are generally more reactive across the pathogens tested, and that S. typhimurium showed the weakest reactivity. The improved AMIDA-based protocol allows for efficient identification of immunoreactive antigens and the profiling of patient reactivity. When coupled with complementary technologies such as immune repertoire sequencing this approach can be applied to high-value applications including vaccine development, biomarker identification, and therapeutic antibody discovery.Science, Faculty of
Graduate
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Mironov, Gleb. "Capillary Electrophoresis - Mass Spectrometry for Bioanalysis". Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/33004.
Testo completoAbstract (sommario):
Bioanalysis is a subdivision of analytical chemistry and deals with biological analytes such as metabolites, proteins, nucleic acids, small molecules, virus particles and entire cells. The rationale of my thesis was to achieve two goals: (i) develop a set of ready to use methods (ii) which are capable providing exact concentrations of analytes as well as kinetic and thermodynamic parameters of their interactions.
To investigate interactions between biomolecules special conditions are required which do not interfere with the course if biomolecule interactions. Establishing these conditions and optimization of separation and detection parameters can be tedious and can take longer than actual analysis of samples. I developed a variety of Capillary Electrophoresis – Mass Spectrometry (CE-MS) methods suitable for bionalalysis.
CE-MS establishes a new paradigm that separation methods together with MS detection can be used as comprehensive kinetic tools. Most previous attempts to use chromatography and electrophoresis for studying nucleic acid interactions were restricted to assuming slow or no equilibrium between reactants. Kinetic CE (KCE) shows that non-zero kinetics and structural dynamics must be taken into account when separation happens. KCE-MS could be a valuable supplement to IM-MS due to the separation of ions in solution according to their size-to-charge ratio.
These methods allowed to reveal new facts about biomolecules and added novel data to the bank of the mankind knowledge. For the best of my knowledge, kinetic parameters for TG2 and thrombin G-quadruplex folding were reported for the first time. I developed a homogeneous method to determine kon, koff and Kd of fast and weak noncovalent interactions between multiple unlabeled ligands (small molecule drugs) and an oligosaccharide (α- or β-cyclodextrin) simultaneously in one capillary microreactor. It has been shown for the first time that KCE can be used to separate and detect the slowly interconverting open and closed conformations of human TG2. It allowed the first direct measurement of the Kd value for calcium binding. Sixteen new substrates were discovered for three aminotransferases (AAT, BCAT, and DAAT). In addition, Viral qCE showed a feasibility to analyse both the count of intact viral particles and sample nucleic acid contamination.
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Jonsson, Andreas. "Mass spectrometry in protein structure analysis /". Stockholm, 2001. http://diss.kib.ki.se/2001/91-628-4716-3/.
Testo completo
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Nelson, Paul Redfield. "Applications of analytical collisional mass spectrometry". Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/27053.
Testo completo
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Mullis, James Onis Jr. "Planar chromatography coupled with mass spectrometry". Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/27124.
Testo completo
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Ho, Stacy Zhanying. "Aerosol sample introduction and mass spectrometry". Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/30517.
Testo completo
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Axford, Stephen Douglas Tabrum. "Mass spectrometry of ions in flames". Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239584.
Testo completo
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Nettleton, Ewan John. "Analysing protein conformations by mass spectrometry". Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298392.
Testo completo
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Florane, H. "Exploring protein conformation with mass spectrometry". Thesis, University of Edinburgh, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.650980.
Testo completoAbstract (sommario):
The first part of this thesis describes the development and viability of a phase I screening system for obtaining a rank order of affinity of novel ligands against the immunophilin, Cyclophilin A (CypA). The naturally occurring inhibitor Cyclosporin A (CsA) was used as a positive control to validate a method for calculating the dissociation constant (Kd). An HPLC autosampler and pumping system was used as a high throughput on-line electrospray ionisation (ESI)-MS sampling system. Optimised ESI conditions were then used to screen novel ligands from 3 combinatorial libraries and approaches for data analysis is discussed. Hydrogen/deuterium exchange (HDX) can be used directly and indirectly as a means for studying protein conformations. Melittin, the major component of honey bee venom is taken here as a model system for studying secondary structure in solution and the gas phase. Comprising a 26 amino acid polypeptide, melittin occupies a random coil in aqueous conditions which can be transformed into an α-helix under increasingly hydrophobic conditions. A variety of HDX techniques were utilised: i) comparing rats of deuterium (d-) uptake by direct infusion – ESI at different pDs and methanol concentrations; ii) PLIMSTEX (protein-ligand interactions by mass spectrometry, titration and HDX) at high and low salt concentrations with varying pDs; iii) gas phase exchange in an LCQ ion trap using He/d-methanol as the bath gas. Melittin was pre-incubated in a variety of methanol concentrations. Comparing results from these different approaches, α-helical retention has been shown to exist in the N-terminal half of the peptide. All the afore-mentioned techniques developed using melittin were adapted for CypA. Comparisons of d-uptake in the presence and absence of CsA shows the ligand to have a stabilising affect on the protein.
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Ben-Farag, Suaad Omran S. "Statistical analysis of mass spectrometry data". Thesis, University of Leeds, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.659026.
Testo completoAbstract (sommario):
The research described in this thesis can be broadly described by term "statistical analysis of mass spectrometry data". Bioinformatics is a new science which attempts to amalgamate statistical methodology with bring statistical thinking and the biological understanding to area which have previously been void of such. Mass spectrometry which is used to study proteins and their functions, is a relatively new field of bioinformatics research. In this thesis we explore three main themes, all of which tackle a different statistical learning method which arises in mass spectrometry. The main focus of the first theme of the research is on using statistical methods to study fragmentation patterns of mass spectrometry experiments. The analysis contained in this theme has been loosely split into parts: firstly, we calculate a probability of a process called cleavage as part of our preliminary analysis to determine which combination of fragmentation site residues were likely to break. In part two, we apply statistical models to investigate factors influencing the relative intensity of fragment ions formed in tandem mass spectrometry experiments. Separate models were formulated for different types of ions as it was thought that different factors may influence the formation of each type of fragment ion. Statistical regression methods are applied to two types of datasets of mass spectra data: tryptic and nontryptic peptide sequences. We find that several factors have a highly significant influence on the relative intensity of fragment ions formed in the experiment.
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Jackson, Anthony Trevor. "Tandem mass spectrometry of polymeric materials". Thesis, University of Warwick, 1995. http://wrap.warwick.ac.uk/44296/.
Testo completoAbstract (sommario):
Mass spectrometry and tandem mass spectrometry (MS/MS) has been employed to analyse peptides (<600 daltons), synthetic polymers of low molecular weight (<10,000 daltons) and a mixture of polymer additives (300-1200 daltons). Mass spectrometry experiments were performed on a four sector mass spectrometer, a tandem quadrupole mass spectrometer and a time-of-flight instrument. High and low energy collision induced dissociation (CID) spectra were obtained by means of a four sector mass spectrometer and a tandem quadrupole instrument respectively. Surface induced dissociation (SID) spectra of peptides were obtained by means of a four sector mass spectrometer with a modified collision cell in the third field free region. Sequence data were generated by SID from protonated and cationated precursor ions of all four peptides analysed. Furthermore, broad metastable ion peaks were observed in the spectra, arising from fragmentation of precursor ions in the field free region between the electric sector and the magnetic sector of the second mass spectrometer. Field desorption was a good ionisation technique for the generation of molecular weight information from the polymer additives used. High energy eID was found to be more applicable than low energy eID to the structural determination of polymer additives as characteristic ions were observed in the spectra. Mechanisms have been proposed for the generation of some of the fragment ions observed. Ultraviolet-matrix assisted laser desorptionlionisation spectra of synthetic polymers of low molecular weight (<10,000 daltons) were used to calculate molecular weight averages. Furthermore, end group information was also obtained from CID spectra of the same polymer samples. End group and structural information was also obtained from polystyrene and a substituted polystyrene by means of FD-MS/MS.
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O'Neill, Karen Elizabeth. "Studies in ion trap mass spectrometry". Thesis, University of East Anglia, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332326.
Testo completo
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Clinton, Rebecca. "Pharmaceutical process analysis by mass spectrometry". Thesis, Nottingham Trent University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.430266.
Testo completo
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Ponce, Alquicira Edith. "Food analyzing using electrospray mass spectrometry". Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324538.
Testo completo
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Owen, Andrew. "Direct liquid sampling process mass spectrometry". Thesis, University of Strathclyde, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431825.
Testo completo
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Dumville, Joanne. "Developments in laser-microprobe mass-spectrometry". Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360826.
Testo completo