Dissertations / Theses on the topic 'Spectrometry'
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Wingerd, Mark A. "A multi-mode spectrometer for atomic emission spectrometry." Diss., Virginia Tech, 1990. http://hdl.handle.net/10919/37396.
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Murray, Jonathan Ernest. "High resolution spectrometry of neutral chromium using a Fourier Transform Spectrometer." Thesis, Imperial College London, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.481779.
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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.
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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.
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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.
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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.
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Burt, Christopher. "Plastic scintillation spectrometry." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/72351/.
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Plastic scintillators provide homeland security organisations with large area, low cost gamma-ray counters at international borders. Currently these detectors connot distinguish between the sources they detect, leading to high false alarm rates during primary screening. These alarms must be followed up by time consuming secondary screening techniques using spectroscopic detectors. Here we review current PVT scintillators and present a range of techniques that optimise their characteristics. By combining these optimisations with Symetrica's spectral deconvolution and isotope identification software, PVTdetectors were given isotope identification ability. Far from being simple gamma-ray counters, these detectors were used to successfully identify a range of complex isotopes, such as Eu-152, Ra-226 and Th-232. The resulting clarity produced by these detectros was impressive, with a measured full width at half maximum of ~5% at 662keV in deconvolved Cs-137 spectrum. Detector designs are also presented here which allow PVT detectors to identify a full range of isotopes during primary screening, potentially eradicating the need for follow up examinations.
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Kurulugama, Kurulugama Lekamlage Ruwan T. "Overtone mobility spectrometry." [Bloomington, Ind.] : Indiana 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:3344776.
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Thesis (Ph. D.)--Indiana University, Dept. of Chemistry, 2009.Title from PDF t.p. (viewed Oct. 8, 2009). Source: Dissertation Abstracts International, Volume: 70-02, Section: B, page: 0988. Adviser: David E. Clemmer.
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Ding, Luyi. "Studies of electrospray/ion mobility spectrometry/time-of-flight mass spectrometry." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0015/NQ48344.pdf.
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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.
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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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Chawner, Ross. "Combined tandem mass spectrometry and ion mobility spectrometry in proteome analyses." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/combined-tandem-mass-spectrometry-and-ion-mobility-spectrometry-in-proteome-analyses(3ba76f18-4703-4f6e-a97f-ee2b1dfb1deb).html.
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Proteomic studies aim to identify, quantify and characterise the full complement of proteins in a cell or organism under a defined set of conditions, and are important to our understanding of cellular mechanisms. However, such studies represent a major analytical challenge. A typical proteome analysis involves enzyme-mediated digestion of complex protein mixtures to yield an even more complex mixture of peptides. Combined reverse-phase liquid chromatography and tandem mass spectrometry is then traditionally utilised to ascertain sequence information from the characteristic peptide sequences. Analytical data derived for the peptides are employed as search terms in database searching of protein sequences derived from gene sequences. The extreme complexity of the peptide mixtures analysed means that additional novel approaches are required to fully interrogate the vast number of tandem mass spectra generated, assigning peptide identity and thereby helping to address demanding biological questions. The research reported here aims to further our understanding of both gas phase peptide/peptide fragment ion structure and peptide fragmentation behaviour using a combination of tandem mass spectrometry and ion mobility measurement.To facilitate the determination of peptide ion collision cross section, a novel standard, QCAL-IM, produced using the QconCAT strategy, has been developed to enable calibration of drift time in Travelling Wave Ion Mobility instruments. The standard facilitates empirical determination of the rotationally averaged collision cross section of any peptide/peptide fragment ion that lies within the calibration range encompassed. QCAL-IM was subsequently utilised to determine the collision cross section of a range of peptide ions produced by Lys-C and Lys-N proteolysis of ‘standard’ proteins. Data produced allowed the effect upon gas phase ion conformation through changing the location of the basic residue lysine within a peptide sequence to be assessed.The fragmentation behaviour of peptide ions produced by a variety of digestion regimes during both collision-induced dissociation (CID) and electron transfer dissociation (ETD) has also been extensively studied. The proteases trypsin and Lys-C are those typically utilised during proteomic studies and peptides produced by each have either the basic residues arginine or lysine at their carboxy-terminus. Secondary enzymatic treatment with the exoprotease carboxypeptidase B cleaves these basic residues from the C-terminus. Tandem mass spectrometric analysis of both tryptic/Lys-C peptides and their CBPB truncated analogue highlights that the dominant fragment ion series observed during both CID and ETD is determined, at least in part, by the location of such basic residues.Finally, studies were undertaken to investigate the factors which may promote/inhibit scrambling of peptide fragment ion sequence, which has recently been shown to take place during CID. The effect of modifying the gas phase basicity of the N-terminal amino acid residue is studied through a combination of derivatisation and synthesis of alternative peptide sequences. Increasing the gas phase basicity is shown to inhibit the observed sequence scrambling while promoting concomitant rearrangement/retention of a carboxyl oxygen at the C-terminus to give enhanced formation of bn+H2O product ion species.
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Koeniger, Stormy Lee Ann. "Multidimensional ion mobility spectrometry coupled to time-of-flight mass spectrometry." [Bloomington, Ind.] : Indiana University, 2006. 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:3230539.
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Thesis (Ph. D.)--Indiana University, Dept. of Chemistry, 2006.Title from PDF t.p. (viewed Nov. 5, 2008). Source: Dissertation Abstracts International, Volume: 67-08, Section: B, page: 4395. Adviser: David E. Clemmer.
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Lu, Yao. "Forensic Applications of Gas Chromatography-Differential Mobility Spectrometry, Gas Chromatography/Mass Spectrometry, and Ion Mobility Spectrometry with Chemometric Analysis." Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1267816777.
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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.
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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).
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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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Townshend, Nichola. "Developments in Raman spectrometry and intracavity laser absorption spectrometry for quantitative analysis." Thesis, University of Strathclyde, 2010. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=25752.
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Jansen, Andrew. "Laser ablation ICP spectrometry." Thesis, Sheffield Hallam University, 1998. http://shura.shu.ac.uk/19868/.
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This thesis reports investigations into laser ablation inductively coupled plasma emission spectrometry for rapid elemental analysis of a diverse range of samples: glasses, aqueous solutions, oils, coated steels and glasses, and biological samples. Bulk analysis of glasses for major, minor and trace elements is reported. Results showed that element emission responses are dependent upon laser operating conditions. With optimised operating conditions of a Q switched laser operating at 60 J for 5 s ablation time with the laser defocused by 5 mm above the sample surface. The limits of detection are in the sub ug g -1 level with precision ranging from 6.6 %RSD for a non volatile element such as boron to 23 %RSD for a volatile element silver. Although the principal aim of using aqueous multielement solutions as novel calibration standards for quantitative analysis of other liquids was not achieved, optimised laser operating parameters needed for microsampling of aqueous solutions and analytical performance data were obtained. The optimum laser operating conditions for a 20 ul sample were found to be the same as for glasses and were as follows: a Q switched laser operating at 60 J for a 5 s ablation time with the laser defocused by 5 mm above the sample surface. Transport efficiencies of approximately 30 % can be achieved, compared to < 1% by pneumatic nebulisation. Also there was no differential loss of elements by laser ablation which may occur with electrothermal vaporisation. Limits of detection were found to be in the sub ug ml -1 level. Precisions were typically between 6.6 and 12 %RSD. The main cause for lack of precision was spattering of the sample. Microsampling of oils by laser ablation proved to be an effective and accurate technique for rapid determination of element concentration without the need for sample filtration or digestion. Precision proved to be better than for aqueous solutions, typically from 3 to 7 %RSD, because of a reduction in spattering. The same optimum laser operating conditions used for aqueous solutions were identical for oils. This thesis reports the first experiments to fully utilise laser ablation as a routine method for quantitative measurement of coating depth for coated steels and glasses. It was found that the peak width at half the maximum height was proportional to the coating thickness (over a range of 1 to 10 um). With optimised laser operating conditions a depth resolution of less than 1 um was achieved. The optimum laser operating conditions were as follows: a Q switched laser ran continuously with a laser lamp energy of 60 J at 10 Hz pulse repetition rate. Finally experiments show the great potential for the use of laser ablation as a microsampling technique for microtome tissue samples. Micro depth analysis of nickel distribution in skin shows that the technique could differentiate between two skin samples with different nickel concentrations. The use of gel multielement standards as a novel calibration technique for analysis of microtome tissue samples has also been demonstrated. Optimum laser operating condition were to use a moderate laser energy of 750 V with the laser defocused 5 mm above the sample surface.
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Chavis, Amy. "Cluster Enhanced Nanopore Spectrometry." VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4290.
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Nanopore sensing is a label-free method used to characterize water-soluble molecules. Recent work describes how Au25(SG)18 clusters improve the single molecule nanopore spectrometry (SMNS) technique when analyzing polyethylene glycol (PEG). This thesis will further study and optimize the enhancement effect resulting from a cluster’s presence. Additionally, a model describing the interaction between a cluster and PEG is developed to assist in understanding this mechanism of enhancement. This thesis will also discuss expanding the SMNS method to detect peptides, using Au25(SG)18 for enhancement, and adjusting solution conditions to improve the sensitivity of the SMNS system for peptide detection. Finally, a model describing the relationship between nanopore current blockades and molecular weight is developed to demonstrate the feasibility of using SMNS as a viable analytical technique for characterizing a wide variety of water-soluble molecules.
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Yuen, Wei Hao. "Ion imaging mass spectrometry." Thesis, University of Oxford, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.564395.
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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.
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Descour, Michael Robert. "Non-scanning imaging spectrometry." Diss., The University of Arizona, 1994. http://hdl.handle.net/10150/186904.
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The objective of imaging spectrometry is to collect three-dimensional data about object space. Two of the three dimensions are spatial. The third dimension is spectral. Current techniques rely on some form of scanning, causing instruments to include moving components and/or to be capable of imaging only static or slowly changing scenes. An interpretation of the problem in terms of computed tomography leads to a system design which can fulfill the objective of imaging spectrometry without scanning. The imaging spectrometer assumes the frame-rate and integration-time properties of its imaging array. The raw data collected by such an instrument must be processed to yield temporally coincident spectral images of the scene. The computed tomography imaging spectrometer is therefore an example of indirect imaging. The three-dimensional frequency-space viewpoint and the associated central slice theorem form the theoretical basis for an understanding of this technique and its limitations. As described here, computed tomography imaging spectrometry belongs to the class of limited-view-angle problems. The spectrometer is treated as a discrete-to-discrete mapping and described accordingly by the linear imaging equation g = Hf + n. The M-element vector g represents the data collected by the spectrometer. The purpose of the instrument and the subsequent processing is the acquisition of the object cube f. In the discrete-to-discrete model, f is approximated as a vector of N independent elements. The vector n represents measurement-computing noise. The M-by-N matrix H embodies the imaging properties of the instrument. We have developed and implemented an experimental method of characterizing H. Such an approach yields a description of the imaging spectrometer which is more accurate than techniques that model the instrument and compute H. Inversion of the imaging equation to find an estimate of f has been best performed by the Expectation-Maximization algorithm. This approach is based on a Poisson likelihood law and therefore the assumption of quantum noise dominating the measurements g.
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Vandervlugt, Corrie Jean. "Computed Tomographic Imaging Spectrometry." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/202975.
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A Computed Tomographic Imaging Spectrometer (CTIS) is an imaging spectrometer which can acquire a hyper-spectral data set in a single snapshot (one focal plane array integration time) with no moving parts. A specially designed dispersing element, which separates light from the three-dimensional object cube into a grid of two-dimensional prismatic diffraction orders, is the key element in the instrument. The capabilities of the CTIS instrument can be improved by employing a more optimized grating design.There were two main goals to this research: (1) to design a novel CTIS disperser that will improve CTIS capabilities over the previous 5x5 disperser and (2) to integrate the new disperser into the CTIS and evaluate its performance compared to the 5x5 disperser. Six new disperser ideas were evaluated based on their performance in a number of computer simulations to determine the most optimal dispersion pattern. A new CTIS disperser incorporating a novel radial design pattern was developed and tested. Reconstruction results of various spatial and spectral targets are presented. Capabilities of the new CTIS instrument incorporating the radial grating are compared to the previous instrument employing a 5x5 disperser. While both dispersers perform similarly for point-source objects, the radial grating performs better than the previous disperser for extended sources.
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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.
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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.
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Brown, Lauren J. "Field asymmetric waveform ion mobility spectrometry-mass spectrometry studies of peptides and proteins." Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/12001.
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Field asymmetric waveform ion mobility spectrometry (FAIMS) is a gas phase atmospheric pressure separation technique that exploits the difference in the mobility of ions in alternating low and high electric fields as they are carried between two electrodes. In this thesis, a miniaturised FAIMS separation step has been applied to increase selectivity, enhance sensitivity and improve the quality of mass spectral data for rapid, high-throughput protein and peptide analysis. In Chapter 2, charge state separations were used to generate pseudo-peptide mass fingerprint data by FAIMS-MS, permitting confident protein identification using ESI sample introduction as an alternative to MALDI-TOF-MS methods. In addition, pre-cursor ions were targeted prior to MS/MS analysis. Chapter 3 describes the analysis of intact proteins by miniaturised FAIMS-MS. Multiple charge states of intact proteins were separated on the basis of differences in differential mobility. Higher charge states were found to be transmitted at similar CVs suggesting that the miniaturised FAIMS device was separating ions on the basis of 3D structure. In addition, multiple species could be observed at the same m/z suggesting the presence of different protein conformers. In Chapter 4, miniaturised FAIMS was used to select ions on the basis of differential mobility prior to in-source collision-induced dissociation CID, LC and ToF-MS analysis for qualitative and quantitative analysis of peptides mixtures. This was applied to the analysis of co-eluting model peptides and tryptic peptides derived from human plasma proteins, allowing precursor ion selection and CID to yield product ion data suitable for peptide identification via database searching.
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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.
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Garabedian, Alyssa Lynn. "Study of Proteoforms, DNA and Complexes using Trapped Ion Mobility Spectrometry-Mass Spectrometry." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3567.
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The characterization of biomolecules and biomolecular complexes represents an area of significant research activity because of the link between structure and function. Drug development relies on structural information in order to target certain domains. Many traditional biochemical techniques, however, are limited by their ability to characterize only certain stable forms of a molecule. As a result, multidimensional approaches, such as ion mobility mass spectrometry coupled to mass spectrometry (IMS-MS), are becoming very attractive tools as they provide fast separation, detection and identification of molecules, in addition to providing three-dimensional shape for structural elucidation. The present work expands the use and application of trapped ion mobility spectrometry-coupled to mass spectrometry (TIMS-MS) by analyzing a range of biomolecules (including proteoforms, intrinsically disordered peptides, DNA and molecular complexes). The aim is to i) evaluate the TIMS platform measuring sensitivity, selectivity, and separation of targeted compounds, ii) pioneer new applications of TIMS for a more efficient and higher throughput methodologies for identification and characterization of biomolecular ions, and iii) characterize the dynamics of selected biomolecules for insight into the folding pathways and the intra-or intermolecular interactions that define their conformational space.
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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.
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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.
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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.
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Gwak, Seongshin. "Comprehensive Analysis of Emerging New Psychoactive Substances by Ion Mobility Spectrometry and Mass Spectrometry." FIU Digital Commons, 2015. http://digitalcommons.fiu.edu/etd/2291.
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In the new era of drug abuse, the proliferation of new psychoactive substances (NPS), commonly referred to as designer drugs or legal highs, has been a global concern. These substances are produced to circumvent current legislation for controlled substances with minor modifications in their chemical structure. Although many efforts have been made previously, the characterization of such substances are still challenging because of (1) the continual emergence of newly identified substances, (2) the lack of a universal screening test for NPS that are structurally similar to each other, and (3) the complex and time-consuming chromatographic techniques currently used. Therefore, it is necessary to develop novel analytical methods that can be readily adapted by forensic laboratories to overcome these challenges.
In this dissertation, various analytical techniques have been evaluated for qualitative analysis of these emerging NPS. For rapid screening purposes, a commercial ion mobility spectrometry with a 63Ni ion source (63Ni-IMS) and also direct analysis in real time coupled to a quadrupole time-of-flight mass spectrometer (DART-QTOF-MS) were investigated first. The results showed that rapid detection by 63Ni-IMS and identification by DART-QTOF-MS can be achieved with sub-nanogram detection capability and high speed total analysis time less than two minutes. In recent developments of gas chromatography mass spectrometry (GC-MS), gas chromatography (GC) has been coupled to state-of-the-art mass spectrometers, including triple quadrupole (MS/MS) and quadrupole time-of-flight (QTOF). It was revealed that the application of GC-MS/MS and GC-QTOF facilitates the unambiguous identification of emerging NPS with a chemical ionization (CI) source. In addition, constitutional isomers of NPS were differentiated with the capabilities of product ion scan and multiple reaction monitoring (MRM) modes. Finally, the coupling of IMS with a mass spectrometer (IMS-MS) was investigated as an alternative confirmatory technique. With the development of an optimal solvent system in the electrospray ionization (ESI) process, the rapid analysis and identification of synthetic cathinone was successfully achieved less than five minutes. As a proof-of-concept, seized drugs samples provided by a local forensic laboratory were analyzed using these developed methods by various analytical techniques. The results from these seized samples are also presented in this evaluation.
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Knapman, Thomas William. "Structural analysis of biomolecules by nanoESI and travelling wave ion mobility spectrometry-mass spectrometry." Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.535122.
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Tam, Maggie. "Liquid phase ion mobility spectrometry." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Dissertations/Fall2006/m_tam_120606.pdf.
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Zhou, Yi. "Microfluidics interfacing to mass spectrometry." College Park, Md. : University of Maryland, 2007. http://hdl.handle.net/1903/7402.
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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.
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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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D'Mellow, Bob. "Digital processing in neutron spectrometry." Thesis, Lancaster University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440406.
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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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Winter, David. "Drug analysis by mass spectrometry." Thesis, University of Canterbury. Chemistry, 1986. http://hdl.handle.net/10092/6560.
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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.
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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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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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Qui, Junyi. "Terahertz spectrometry applied to proteins." Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/24777.
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Electromagnetic radiation from the radio waves used in nuclear magnetic resonance spectroscopy through to X-rays used in crystallography have provided a wealth of knowledge about the structure, function, and dynamics of protein molecules. Terahertz waves, the topic of this thesis, are lower in frequency than radiation from the infrared, not to the frequencies of individual bond vibrations, but to the frequency range where slower longer range protein librations (low frequency vibrations) are expected to occur. The role of low frequency protein dynamics remains controversial, with some arguing that these motions are crucial for enzyme and protein function. Terahertz spectroscopy may provide key evidence to contribute to this interdisciplinary debate. In this thesis, terahertz (THz) spectroscopy has been applied in studying a number of proteins experimentally. In the first results chapter, the effect of protein concentration and ionic strength in the 0.1-2.5 THz region was investigated using Terahertz time domain spectroscopy. The results confirm the presence of terahertz excess for a number of proteins, which results from the increased absorption of THz waves when protein is introduced into the system. THz spectroscopy was then used to detect the difference between a folded protein, myoglobin, and folding intermediates, including the molten globule form, apomyoglobin. The results collected using THz spectroscopy were unable to differentiate between the folded and molten globule states. A further study was susceptible to the formation of higher order protein complexes and explored structures formed using PduA*. These experiments were primarily biochemical in nature with showing that PduA* assembles into nanotubes of 20nm diameter in vitro. The final results chapter explores the sub-THz circular dichroism signal from a vector network analyser driven by quasi-optical circuits. Wherever possible, the THz experiments were benchmarked using established analytical techniques.
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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.
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Cobice, Diego Federico. "Mass spectrometry imaging of steroids." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/21032.
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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.
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Salter, Tara La Roche. "Metrology for ambient mass spectrometry." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/28748/.
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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.
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McClure, Thomas Dale. "Biomedical applications of mass spectrometry." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185490.
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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.
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Offei, Felix. "Denoising Tandem Mass Spectrometry Data." Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etd/3218.
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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.
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SPEZZANO, ROBERTO. "Lipids and Mass Spectrometry Application." Doctoral thesis, Università degli Studi di Milano, 2019. http://hdl.handle.net/2434/647470.
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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.
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Harris, Glenn A. "Fundamentals of ambient metastable-induced chemical ionization mass spectrometry and atmospheric pressure ion mobility spectrometry." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41147.
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Molecular ionization is owed much of its development from the early implementation of electron ionization (EI). Although dramatically increasing the library of compounds discovered, an inherent problem with EI was the low abundance of molecular ions detected due to high fragmentation leading to the difficult task of the correct chemical identification after mass spectrometry (MS). These problems stimulated the research into new ionization methods which sought to "soften" the ionization process. In the late 1980s the advancements of ionization techniques was thought to have reached its pinnacle with both electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI). Both ionization techniques allowed for "soft" ionization of large molecular weight and/or labile compounds for intact characterization by MS. Albeit pervasive, neither ESI nor MALDI can be viewed as "magic bullet" ionization techniques. Both techniques require sample preparation which often included native sample destruction, and operation of these techniques took place in sealed enclosures and often, reduced pressure conditions.
New open-air ionization techniques termed "ambient MS" enable direct analysis of samples of various physical states, sizes and shapes. One particular technique named Direct Analysis In Real Time (DART) has been steadily growing as one of the ambient tools of choice to ionize small molecular weight (< 1000 Da) molecules with a wide range of polarities. Although there is a large list of reported applications using DART as an ionization source, there have not been many studies investigating the fundamental properties of DART desorption and ionization mechanisms.
The work presented in this thesis is aimed to provide in depth findings on the physicochemical phenomena during open-air DART desorption and ionization MS and current application developments. A review of recent ambient plasma-based desorption/ionization techniques for analytical MS is presented in Chapter 1. Chapter 2 presents the first investigations into the atmospheric pressure ion transport phenomena during DART analysis. Chapter 3 provides a comparison on the internal energy deposition processes during DART and pneumatically assisted-ESI. Chapter 4 investigates the complex spatially-dependent sampling sensitivity, dynamic range and ion suppression effects present in most DART experiments. New implementations and applications with DART are shown in Chapters 5 and 6. In Chapter 5, DART is coupled to multiplexed drift tube ion mobility spectrometry as a potential fieldable platform for the detection of toxic industrial chemicals and chemical warfare agents simulants. In Chapter 6, transmission-mode DART is shown to be an effective method for reproducible sampling from materials which allow for gas to flow through it. Also, Chapter 6 provides a description of a MS imaging platform coupling infrared laser ablation and DART-like phenomena. Finally, in Chapter 7 I will provide perspective on the work completed with DART and the tasks and goals that future studies should focus on.
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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.
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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.
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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.
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Adams, Kendra J. "Discovery and Targeted Monitoring of Biomarkers Using Liquid Chromatography, Ion Mobility Spectrometry , and Mass Spectrometry." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3568.
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The complexity of biological matrices makes the detection and quantification of compounds of interest challenging. For successful targeted or untargeted identification of compounds within a biological environment, the use of complementary separation techniques is routinely required; in many situations, a single analytical technique is not sufficient. In the present dissertation, a multidimensional analytical technique was developed and evaluated, a combination of new sample preparation/extraction protocols, liquid chromatography, trapped ion mobility and mass spectrometry (e.g., LC-TIMS-MS and LC-TIMS-MS/MS). The performance of these techniques was evaluated for the detection of polybrominated diphenyl ethers metabolites, polychlorinated biphenyls metabolites in human plasma, opioid metabolites in human urine, and lipids in Dictyostelium discoideum cells. The new workflows and methods described in the body of this dissertation allows for rapid, selective, sensitive and high-resolution detection of biomarkers in biological matrices with increased confidence, sensitivity and shorter sample preparation and analysis time.
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Fälth, Savitski Maria. "Improved Neuropeptide Identification : Bioinformatics and Mass Spectrometry." Doctoral thesis, Uppsala universitet, Institutionen för farmaceutisk biovetenskap, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9400.
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Bioinformatic methods were developed for improved identification of endogenous peptides using mass spectrometry. As a framework for these methods, a database for endogenous peptides, SwePep, was created. It was designed for storing information about endogenous peptides including tandem mass spectra. SwePep can be used for identification and validation of endogenous peptides by comparing experimentally derived masses of peptides and their fragments with information in the database. To improve automatic peptide identification of neuropeptides, targeted sequence collections that better mimic the peptidomic sample was derived from the SwePep database. Three sequence collections were created: SwePep precursors, SwePep peptides, and SwePep predicted. The searches for neuropeptides performed against these three sequence collections were compared with searches performed against the entire mouse proteome, and it was observed that three times as many peptides were identified with the targeted SwePep sequence collections. Applying the targeted SwePep sequence collections to identification of previously uncharacterized peptides yielded 27 novel potentially bioactive neuropeptides. Two fragmentations studies were performed using high mass accuracy tandem mass spectra of tryptic peptides. For this purpose, two databases were created: SwedCAD and SwedECD for CID and ECD tandem mass spectra, respectively. In the first study, fragmentation pattern of peptides with missed cleaved sites was studied using SwedCAD. It was observed that peptides with two arginines positioned next to each other have the same ability to immobilize two protons as peptides with two distant arginines. In the second study, SwedECD was used for studying small neutral losses from the reduced species in ECD fragmentation. The neutral losses were characterized with regard to their specificity and sensitivity to function as reporter ions for revealing the presence of specific amino acids in the peptide sequence. The results from these two studies can be used to improve identification of both tryptic and endogenous peptides. In summary, a collection of methods was developed that greatly improved the sensitivity of mass spectrometry peptide identification.