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1
Price, Daniel Charles. "Radio astronomy instrumentation for redshifted hydrogen line science." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:3185b622-9aba-4c0f-995b-eceb50a5a49c.
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This thesis presents instrumentation with which to measure the abundance of neutral hydrogen gas in the Universe. Measuring where the Universe’s hydrogen is, and tracing how its distribution evolves with time, holds the key to understanding how galaxies evolve, the nature of dark energy, and how the first cosmic structures formed. In particular, this thesis looks at instrumentation for 21-cm intensity mapping telescopes. In 21-cm intensity mapping, the collective emission of many galaxies is measured, without individual detections. This technique promises to allow detection of the baryonic acoustic oscillation peaks in the power spectrum of the Universe’s matter distribution. Such a detection would increase constraints on cosmological parameters. There are two main approaches to designing a 21-cm intensity mapping instruments: using a filled aperture instrument such as a single-dish telescope, or using a sparse aperture instrument such as an interferometric array of dipoles. This thesis investigates analogue components for a sparse aperture instrument operating at 1.0-1.5 GHz. As part of this work, a 16-element sparse aperture array was designed and constructed. To test the array’s performance, field testing was conducted; the results of which are presented here. In addition to this, I have designed a new digital spectrometer for redshifted hydrogen line science, named HISPEC. A copy of this spectrometer has been installed on the Parkes 64 m telescope, as a digital signal processor for the 21-cm multibeam receiver. HISPEC has increased instantaneous bandwidth, higher interchannel isolation, and improved quantization efficiency as compared to the existing backend, MBCORR. The HISPEC equipped multibeam receiver is an ideal instrument for 21-cm intensity mapping at redshifts z<0.2.
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Hochgürtel, Stefan [Verfasser]. "Efficient implementations of high-resolution wideband FFT-spectrometers and their application to an APEX Galactic Center line survey / Stefan Hochgürtel." Bonn : Universitäts- und Landesbibliothek Bonn, 2013. http://d-nb.info/104497124X/34.
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Pospíchal, David. "Systém pro měření lokálních IR spekter." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442520.
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The diploma thesis deals with the design of a system for measuring infrared spectra from local areas of samples. The theoretical part describes the electromagnetic waves and related phenomena. Furthermore, the semiconductor junction and solar cells are discussed. The following is a basic description of line spectrometers. In the practical part, a suitable arrangement of the whole system, collimator design, and especially the core of the whole work, ie control software and signal processing, are proposed.
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Galhena, Asiri S. "Implementation of an In-line Surface-induced Dissociation Device in a Quadrupole Time-of-flight Instrument and Its Performance." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/195832.
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The focus of this dissertation is the introduction of surface-induced dissociation (SID) into a commercially available quadrupole time-of-flight mass spectrometer as an alternative ion fragmentation method. The performance of the SID device was characterized and its applications were demonstrated by dissociating peptides, proteins, inorganic salt clusters and non-covalent protein complexes. The SID setup allowed direct comparison of SID with conventional collision-induced dissociation (CID) on the same instrument, taking advantage of the characteristics of Q-TOF instrumentation, including extended mass range, high sensitivity and resolution. With the SID setup installed, no significant reduction of the ion transmission was evident. SID fragmentation patterns of peptides are, in general, similar to CID, with slight differences in the relative intensities of immonium ions, backbone cleavage b- versus y- type ions, and y- versus y-NH3 ions. This suggests enhanced accessibility to high energy/secondary fragmentation channels with SID. SID studies on cesium iodide clusters (CsI) also revealed that SID deposits more internal energy.The utility of mass spectrometric methods to probe the gas phase cyclization process was studied with [D-Ala2]-Leucine Enkephalin amide. This peptide showed prominent formation of the [M-NH3]+ ion which is believed to be the linear b5 ion with a C-terminal oxazolone structure. Other fragments in the spectra indicate that the linear b5 ion undergoes cyclization, subsequent ring opening and further dissociation to rearranged fragments that cannot be explained by the initial sequence. The similarities between the cyclic and b5-ion from the linear peptide indicated the formation of a heterogeneous ion population and this is further supported by gas-phase H/D exchange experiments. An ion funnel interface to improve ion transmission at high pressures was tested in a custom built quadrupole-surface-quadrupole instrument. The ion transmission efficiency for selected bio-molecules such as YGGFLR, insulin chain-B, ubiquitin and cytochrome c showed to approach almost 90%, with the funnel interface installed. The ion transmission efficiency was effected by several factors including: the size of the analyte, the DC gradient, the RF frequency, and the RF amplitude. The higher fragmentation efficiencies for SID in the presence of the funnel interface indicated higher internal energy deposition for the funnel interface.
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Bell, Christopher Robert. "Multi-lined Interferometric Stellar Oscillation Spectrometer (MISOS)." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46672.
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Dunn, Warwick Brian. "The off-line and on-line analysis of liquid process streams by mass spectrometry." Thesis, University of Hull, 1996. http://hydra.hull.ac.uk/resources/hull:4651.
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The work presented in this thesis describes the development and validation in the laboratory of four techniques employed for the off-line and on-line analysis of liquid chemical process streams by mass spectrometry, without previous chromatographic separation of sample components. The four techniques were total vaporisation analysis, headspace analysis, membrane introduction mass spectrometry and atmospheric pressure ionisation-mass spectrometry. The technique of total vaporisation analysis completely vaporises liquid samples in a gas chromatograph heated injection inlet and analyses the vapour created with a mass spectrometer. Headspace analysis and membrane introduction mass spectrometry provide partial and selective transfer of compounds from the liquid sample phase to the gas phase and the subsequent analysis of the gas phase with a mass spectrometer. Headspace analysis has no third phase separating the liquid and gas phases whereas membrane introduction mass spectrometry places a membrane between the two phases. All three techniques were validated using an electron-impact quadrupole mass spectrometer and two model streams; acetone (analyte) in water and methyl iodide (analyte) in acetic acid. As an alternative strategy atmospheric pressure ionisation-mass spectrometers ionise samples in ion sources operating at atmospheric pressure. The techniques of electrospray ionisation and atmospheric pressure chemical ionisation were investigated for the analysis of formic, acetic and propionic acids present in water and other carboxylic acids. The techniques of total vaporisation analysis, headspace analysis and membrane introduction mass spectrometry provided low p.g m1' or g 11 limits of detection for acetone and methyl iodide with relative standard deviation values for replicate analyses of 100 pg ml' standards of less than 10 % in most cases. Off-line and on-line total vaporisation analysis and off-line headspace analysis provided accurate determination of acetone in similar process samples, whereas the matrix affected the accuracy of the determination when the techniques of on-line headspace analysis and membrane introduction mass spectrometry were employed. Electrospray ionisation could also detect formic, acetic and propionic acids in aqueous or carboxylic acid matrices at concentrations of and possibly less than 100 tg nil1 . Atmospheric pressure chemical ionisation could only detect carboxylic acids present in aqueous matrices at concentrations of 100 tg ml' or greater.
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Gallavardin, Stéphane. "Analysis concepts of aerosols by on-line aerosol mass spectrometry." [S.l.] : [s.n.], 2006. http://mediatum2.ub.tum.de/doc/603768/document.pdf.
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Pitts, Leslie John. "On-line systems for automated sample introduction in atomic spectrometry." Thesis, University of Plymouth, 1995. http://hdl.handle.net/10026.1/1807.
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Offley, Stephen George. "Aspects of flow injection atomic absorption spectrometry." Thesis, Loughborough University, 1992. https://dspace.lboro.ac.uk/2134/25489.
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The literature relevant to the generation of volatile hydrides for analytical atomic spectroscopy has been reviewed, with particular reference to atomic absorption spectrometry (AAS). This reveals some conflicting information concerning the nature of various interference effects and strategies to overcome them. The use of flow injection (FI) procedures has been demonstrated by several research groups, to be beneficial. A review of the literature concerning the application of FI techniques to AAS shows that there is a sustained interest in the use of such a combination for analytical purposes. In particular, an interest in the on-line coupling of chemical pretreatment of samples is evident. Atomic absorption spectrometry has a limited working range and requires frequent calibration, consequently, there is a need for a rapid, precise on-line dilution procedure. The potential of FI systems with wide bore manifold tubing for on-line dilution was assessed and found to be limited by variations in dispersion coefficient arising from differences in specific gravities between the sample and carrier fluids. This could be overcome only by the use of unrealistically high flow rates. The use of FI procedures for the generation of volatile hydrides of selenium and arsenic was investigated. Optimization studies of system parameters, including the atomization step, were undertaken which demonstrated the benefits in applying FI in hydride generation atomic absorption spectrometry (HGAAS). Analytical methods were devised and evaluated for the determination of Se in copper metal and As in nickel alloy. These procedures involved the use of an on-line matrix removal step in which potentially interfering matrix elements were retained on a strong cation exchange resin (Dowex 50W). The manifold was designed so that the FI value acted as the interface between the matrix isolation stage and the vapour generation stage, a strategy which allowed independent optimization of each stage. Location of the ion exchange resin in the sample loop of a six-port rotary valve allowed the resin to be regenerated easily and rapidly, with a throughput capability of the order of 50 h⁻¹ and permit the proposed full automation of the whole analytical procedure. In the determination of As in nickel alloy a novel stopped-flow pre-reduction step was developed to permit AsIII quantification, therefore, achieve optimum sensitivity. The two systems permitted limits of detection for Se and As of 2.1 and 3.9 ng ml⁻¹ respectively. Direct comparisons were made with existing matrix isolation systems to emphasise the benefits of system design.
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Zettersten, Camilla. "On-line Electrochemistry Electrospray Ionisation Mass Spectrometry : Method Development and Applications." Doctoral thesis, Uppsala universitet, Analytisk kemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-99329.
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This thesis deals with studies of on-line electrochemistry electrospray ionisation mass spectrometry (EC/ESI-MS). It is shown that the use of EC/ESI-MS demands optimal coupling characteristics. Pre-concentration and desalting, due to matrix exchange, were demonstrated for the model substance 1-hexanethiol in an EC/ESI-MS setup. The setup was also used for investigations of the oxidation states of the manganese complex [Mn2(bpmp)(µ-OAc)2][ClO4], where bpmp is a 2,6-bis[[N,N-di(2-pyridylmethyl)amino]methyl]-4-methylphenol compound. The manganese complex, which is relevant to artificial photosynthesis, was found to be a good model compound for the EC/ESI-MS studies, thanks to its many oxidation states. For the first time, the presence of the Mn(III,IV) state of the manganese complex was demonstrated in the studies. During the experimental work, the importance of the electrode positioning within the electrochemical cell was investigated. Different EC cell configurations were studied using the manganese complex as a model substance. It was clearly shown that the EC cell design influences the distribution between the peaks in the mass spectra - not only for manganese complexes and Olsalazine but also for 4-chloroaniline. A previously unknown comproportionation reaction was found for 4-chloroaniline involving the oxidised dimer, 4-[(4-chlorophenyl)imino]-2,5-cyclohexadien-1-imine. This reaction explained the unexpected presence of the signal due to the reduced dimer, 4-amino-4'-chlorodiphenylamine, in the mass spectra. Furthermore, it was shown that EC/ESI-MS was successful in conjunction with miniaturised gold wire electrodes in a PDMS chip within which dopamine was oxidised with a conversion efficiency of 30%. The oxidation products of dopamine were detected after 0.6-1.2 seconds for 1.0 and 0.5 µl/min, respectively. The combination of electrochemically controlled solid-phase extraction (EC-SPE) with ESI-MS was found to be less straightforward than detecting anions pre-concentrated on a polypyrrole coated electrode with EC-SPE/ICP-MS. The on-line combination of liquid chromatography with EC/ESI-MS/MS for studying antioxidants in yellow onion extracts was shown to be fast and a relatively easy complement to classical antioxidant activity determinations.
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Murphy, James Robert. "On-line sample pretreatment of environmental samples for use with atomic spectrometry." Thesis, University of Plymouth, 1998. http://hdl.handle.net/10026.1/1884.
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The objective of this study was to develop novel techniques for on-line sample pre-treatment for use with atomic spectroscopy. Preconcentration of the analytes using either complexation of the analyte(s) on an analytical column or by in-situ (in atomiser) trapping on a pre-coated graphite tube has been used. The samples were manipulated using flow injection analysis and detection achieved in most cases by ETAAS. All aspects of the study are supported by reference to the literature. Using the above approach, a new method has been developed to determine mercury in environmental (sediment) and biological (tuna fish) samples. This approach successfully achieved a sample throughput of 20-30 sample per hour, with a method detection limit of 0.2 ng g*^ (3a) and a precision of less than 10% at the 0.1 ug g"^ level. An interference study was conducted and seven elements ( As\, Cd", Cu", Ni", Pb". Sb'' and Se"") shown to give less than a 5% interference when the interferent concentration was 2 orders of magnitude greater than the Hg. Silver showed a 9% interference when one order of magnitude greater than the Hg. The technique of "in atomiser trapping" was applied to the determination of As, Bi, Sb and Se, in lake water samples. The hydrides were sequestrated upon an Ir coated graphite tube and the instrumental and chemical parameters optimised for multi-element determinations. Iridium has been identified as the best trapping material (coating) for multi-element determinations. The final method gave detection limits of 0.82, 0.04, 0,26 and 0.29 ug 1'^ (500 ul sample loop) for As, Bi, Sb and Se respectively. A characteristic mass of 177 pg for As, 91 pg for Bi, 107 pg for Sb and 90 pg for Se was achieved. Good agreement was obtained with certified and standard reference materials and the method was successfully applied to the determination of As, Bi, Sb and Se in lake water samples. Six elements (Cd, Cu, Fe, Mn, Ni and Pb) were selected for determination in seawater samples by multi-element on-line column preconcentration. The sample stream was mixed on-line with a buffered solution of diethylammonium dithiocarbamate (DDDC). and the metal-DDC complex retained upon a Cie RP silica column. Ethanol was then used to elute the metals from the column directly into the graphite tube. Disappointing results, were obtained due to interference problems, and although more work is required before this approach may be routinely used, it is shown to have potential for the future. Overall, this study has shown that novel methods employing flow injection methodologies for separation and preconcentration are a viable way to prepare environmental sample for analysis by ETAAS. Further it has demonstrated that multi-element analysis is possible for low levels of analyte despite the presence of troublesome matrices, although further work is required to achieve the ultimate goal of a universal method suitable for all analytes irrespective of the sample type.
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Brahma, Noel Kumar. "The on line determination of mercury in process streams using atomic spectrometry." Thesis, University of Plymouth, 2000. http://hdl.handle.net/10026.1/2040.
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On-line systems for monitoring mercury in liquid and gaseous production and waste streams have been developed, utilising atomic fluorescence spectrometry (AFS) as the basis for detection. Instrumentation has been designed for unattended continuous operation. Laboratory chemistries for the vapour generation of mercury, normally performed off-line in batch mode, have been adapted and optimised for continuous, flow-injection analysis for varying sample types and chemical forms of mercury. The system has typical analysis cycle of 7 minutes, a limit of detection of 10 pg ml ˉ¹ a linear range up to 100 µg ml ˉ¹ and has been applied in industrial environments for the continuous monitoring of mercury in incineration wastewater and sulphuric acid. The system was validated by on-site trials for periods of one week, during which time comparative off-line laboratory measurements showed good agreement. An automated system for monitoring mercury in natural gas streams has also been developed and validated by laboratory and on-site industrial trials. A heated pressure let-down system was designed in order to facilitate sampling of high-pressure gas streams without condensation of heavier fractions. The heated sampling line was interfaced with an automated system for trapping mercury, from variable volumes of gas, onto gold amalgamation traps, with subsequent desorbtion and analysis by AFS. The method detection limit for a 58 litre sample of natural gas was 30 pg m ˉ³ which was sufficient to determine residual mercury in natural gas streams even after mercury scrubbing had been performed. The system was validated by laboratory trials and spiking experiments during on-site trials at a gas processing facility, which resulted in complete installation and commissioning.
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Gilmor, Christopher Stephen Robertson. "In-line color monitoring of polymers during extrusion using a charge-coupled device spectrometer." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0018/MQ58717.pdf.
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CHEN, JIANWEI. "ON-LINE INTERROGATION OF PEBBLE BED REACTOR FUEL USING PASSIVE GAMMA-RAY SPECTROMETRY." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1096255485.
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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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McArthur, Paul. "Numerical analysis of open-ended coaxial line probes and its application to in-vivo dielectric measurements." Thesis, King's College London (University of London), 1989. https://kclpure.kcl.ac.uk/portal/en/theses/numerical-analysis-of-openended-coaxial-line-probes-and-its-application-to-invivo-dielectric-measurements(e5dde497-6cb0-4076-aa33-81890463d680).html.
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Goodwin, Richard J. A. "Microsampling and on-line separation techniques for mass spectrometry : analysis of single fungal cells." Thesis, University of Edinburgh, 2006. http://hdl.handle.net/1842/12042.
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My research during this interdisciplinary investigation was to primarily focus on the development of novel single cell sampling and analysis methods. Using micromanipulation, microsampling and mass spectroscopic analysis techniques to determine the concentration of biologically relevant molecules quantitatively from living fungal cells, as well as to study the uptake of externally applied compounds. Evaluation of a range of on-line separation techniques, including Capillary Liquid Chromatography (CapLC), nanoLC and capillary electrophoresis (CE) was made for suitability to be coupled to a range of mass spectrometers for the analysis of fungal cytoplasm. Techniques for microsampling at the single cell level from the model organism, Neurospora crassa, and transfer of the sample from under the microscope for analysis by mass spectrometry, following on-line separation, were developed. Capillary electrophoresis electrospray mass spectrometry (CE-ESI-MS) was used to measure intra cellular concentrations of trehalose, quantitatively, with mechanisms developed for detection of external contamination of the samples taken from viable, actively growing cells of Neurospora crassa, by the use of laser induced fluorescence (LIF). The measured concentration for intra-cellular disaccharide was determined to be 1.3mM by the methods developed and described during this thesis. In addition, topical applications of fungicide were made, with intra-cellular measurements taken by single cell analysis. Following application of 14.8μM azoxystrobin, the fungicide under investigation at saturation concentration in water, intra-cellular concentrations were measured at 9.9μM after 5 minutes.
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Durmaz, Tunay. "Multi-hit delay line anode detectors in experiments involving collisions of highly charged ions with molecules." abstract and full text PDF (free order & download UNR users only), 2006. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1433296.
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Lo, Fu-kiu, and 盧富嬌. "Multi-residue analysis of pesticides using on-line two dimension liquid chromatography-tandem mass spectrometry." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47869951.
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This thesis begins with an examination of the feasibility of using the Quick, Easy, Cheap,
Effective, Rugged, and Safe (QuEChERS) method, and its variants, for the co-extraction of
nonpolar and polar pesticides, including highly polar quaternary ammonium salts (QA) and
organophosphates (OP). QuEChERS was performed on a mixture of nine different chemical
classes of pesticides, with triphenyl phosphate (TPP) as the internal standard, on aqueous
Chinese lettuce samples, at 0.1 and 1.0 μg/mL levels. QuEChERS provided superior sample
recovery and precision (RSD) for nonpolar pesticides than it did for its polar variants, including
most of the polar pesticides and several carbamates, as judged from quintuplicate analyses. A
modification of the extraction buffer and cleanup reagent significantly enhanced the recovery of
highly polar QA and carbamates at sub–microgram-per-milliliter levels, while maintaining the
performance of the other nonpolar pesticides. Thus, QuEChERS is a versatile and convenient
methodology for multi-residue analyses, although unambiguous confirmation and quantification
of some polar pesticides, namely chlormequat, mepiquat, and glyphosate, required separate
analyses using tedious and time-consuming single-residue methods.
Liquid chromatography/tandem mass spectrometry (LC-MS/MS) provides the potential
advantages of low detection limits, simple sample preparation procedures, and high selectivities
for multi-residue analyses of organic toxics in food. In this study, a novel methodology based on
LC-MS/MS was developed for the simultaneous analyses of both polar and nonpolar pesticides;
an online-coupled hydrophilic-interaction chromatography/reversed-phase (HILIC-RP)
separation platform, featuring a HILIC column for online sample enrichment and a downstream
high-flow injector for solvent mixing and reconditioning, was constructed to allow efficient,
concomitant analyses of both hydrophilic and hydrophobic pesticides from a single sample
injection event. The performance of the HILIC-RP system, verified using a standard pesticide
mixture, was satisfactory. 6 out the 7 polar pesticides were successfully retained on the HILIC
column and 11 out of the 15 nonpolar pesticides were transferred to and separated by the RP
column; the remaining compounds were determined as flow-through prior to the HILIC
separation. No sensitivity loss of the polar pesticides was observed when using this hyphenated
system. The calibration curves for 20 out of the 22 standard pesticides exhibited excellent linear
responses (R2 > 0.995) over a typical working concentration range. The performance of the
HILIC-RP platform was comparable with those of individual one-dimensional HILIC and RP
analyses, thereby potentially eliminating redundant quantification procedures and allowing highthroughput
multi-residue analyses of toxic organic compounds.published_or_final_version
Chemistry
Master
Master of Philosophy
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Sarvaiya, Hetal Abhijeet. "Mass Spectrometric Characterization of the MCF7 Cancer Cell Line: Proteome Profile and Cancer Biomarkers." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/42169.
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The discovery of cancer biomarkers is crucial in the clinical setting to facilitate early diagnosis and treatment, thereby increasing survival rates. Proteomic technologies with mass spectrometry detection (MS) have the potential to affect the entire spectrum of cancer research by identifying these biomarkers. Simultaneously, microfabricated devices have evolved into ideal analysis platforms for minute amounts of sample, with promising applications for proteomic investigations and future biomarker screening. This thesis reports on the analysis of the proteomic constituents of the MCF7 breast cancer cell line using a shotgun 2-D strong cationic exchange/reversed phase liquid chromatography electrospray ionization tandem mass spectrometry (SCX/RP-LC-ESI-MS/MS) protocol. A series of optimization strategies were performed to improve the LC-MS experimental set-up, sample preparation, data acquisition and database searching parameters, and to enable the detection and confident identification of a large number of proteins. Over ~4,500 proteins were identified using conventional filtering parameters, and >2000 proteins using a combination of filters and p-value sorting. Of these, ~1,950 proteins had p<0.001 (~90%) and more than half were identified by ≥ 2 unique peptides. About 220 proteins were functionally involved in cancer related cellular processes, and over 100 proteins were previously described in the literature as potential cancer markers. Biomarkers such as PCNA, cathepsin D, E-cadherin, 14-3-3-sigma, antigen Ki-67, TP53RK, and calreticulin were identified. These data were generated by subjecting to mass spectrometric analysis ~42 µg of protein digest, analyzing 16 SCX peptide fractions, and interpreting ~55,000 MS2 spectra. Total MS time required for analysis was 40 h.
Selective SCX fractions were also analyzed by using a microfluidic LC platform. The performance of the microchip LC was comparable to that obtained with bench-top instrumentation when similar experimental conditions were used. The identification of 5 cancer biomarkers was enabled by using the microchip LC platform. Furthermore, this device was also capable to analyze phosphopeptides.Master of Science
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Carroll, J. H. "Development and application of probe atomisation in line-source and continuum-source electrothermal atomic absorption spectrometry." Thesis, University of Strathclyde, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382344.
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Schiarea, Silvia. "Mass spectrometry-based characterisation of the secretome of pancreatic cancer cell lines." Thesis, Open University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520740.
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Jones, Megan Renee. "Investigation of the Barrett's esophagus cell line by capillary electrophoresis /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/8573.
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Surdem, Sedat. "On-line Preconcentration, Speciation And Determination Of Chromium By Flame Atomic Absorption Spectrometry (faas) And Chemiluminescence (cl)." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12604979/index.pdf.
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ABSTRACT
Toxicological studies have shown that the degree of toxicity of some elements depends on the chemical form in which the element is present. Chromium (III) is considered as an essential micronutrient for human whereas chromium (VI) is a potentially carcinogenic agent. So the speciation of inorganic chromium in environmental samples is required for accurate assessment of pollution levels. The chromium content in natural water is usually very low, and a preconcentration is often necessary prior to the determination.
A sensitive and selective preconcentration and speciation procedure is developed for the determination of trace and ultra trace amounts of chromium species by utilizing chemiluminescence (CL) and flame atomic absorption spectrometric (FAAS) techniques. The performances of amino silica-gel, amino sol-gel, mercapto silica-gel beads and metal oxides for solid phase extraction of chromium are examined either in column or batch type studies. Considering the advantage of concentrating Cr(III) and Cr(VI) ions separately simply by adjusting the pH of the medium, amino silica-gel resin is chosen in this study. The influences of different experimental parameters on the separation and preconcentration of chromium species such as pH, eluent concentration, flow rate, particle size of the resin are investigated.
Chemiluminescence detection studies are performed by using the catalytic effect of Cr (III) on the reaction between luminol and hydrogen-peroxide and Cr (VI) is detected after reduction to Cr (III). Luminol and H2O2 concentrations and the pH of the medium are optimized to increase the sensitivity of the system.
Chemiluminescence is inherently a very sensitive technique. When a preconcentration step is included in the CL mesurement of very low concentrations of chromium is possible to determine. Indeed, a 25-fold enhancement in sensitivity of chromium ions is achieved after incorporating amino silane&ndashgel colums in the system and 0.2 &
#61549
g/L of chromium (corresponds to the concentration of chromium in natural waters) was measured. A fully automated FI-CL system is designed that allows all necessary operations to be performed on-line. This system allows the pre-conditioning of micro-columns with different buffer solutions
adsorption of chromium species in micro-columns
washing these columns to remove interfering matrix components
elution of the species with minimum volume
transporting the species and chemiluminescence reagents to the cell
and, finally, cleaning of all pertinent conduits in the FIA-system in order to prevent carry-over between individual samples.
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Reyes, Villegas Ernesto. "New on-line mass spectrometric tools for studying urban organic aerosol sources." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/new-online-mass-spectrometric-tools-for-studying-urban-organic-aerosol-sources(afe1d185-5db9-4aae-a60c-761293c6b30d).html.
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Atmospheric aerosols have been shown to have a significant impact on air quality and health in urban environments. Organic aerosols (OA) are one of the main constituents of submicron particulate matter. They are composed of thousands of different chemical species, which makes it challenging to identify and quantify their sources. OA sources have been previously studied; however quantitative knowledge of aerosol composition and their processes in urban environments is still limited. The results presented here investigate OA, their chemical composition and sources as well as their interaction with gases. On-line measurements of species in the particle and the gas phase were performed both from field-based and laboratory studies. Aerosol Mass Spectrometers (AMS) were used together with the Chemical Ionisation Mass Spectrometer (CIMS) and the Filter Inlet for Gases and AEROsols (FIGAERO). Two ambient datasets were analysed to develop methods for source apportionment, using the Multilinear Engine (ME-2), in order to gain new insights into aerosol sources in Manchester and London. Long-term measurements in London allowed the opportunity to perform seasonal analysis of OA sources and look into the relationship of hydrogen-like OA (HOA) and heavy- and light-duty diesel emissions. The seasonal analysis provided information about OA sources that was not possible to observe on the long-term analysis. During Bonfire Night in Manchester, with high aerosol concentrations, particularly biomass burning OA (BBOA), it was possible to identify particulate organic oxides of nitrogen (PON), with further identification of primary and secondary PON and their light absorbing properties. Through laboratory work, new insights into cooking organic aerosols (COA) were gained, a higher relative ion efficiency (RIEOA) value of around 3.3 for OA-AMS compared with the typical RIEOA of 1.4 was determined, which implies COA concentrations are overestimated when using the RIEOA value of 1.4. Dilution showed to have a significant effect on food cooking experiments, increasing both the gas/particle ratios and the O:C ratios. The data generated in this work, OA-AMS mass spectra and markers from both gas and particle phase identified with FIGAERO-CIMS, provide significant information that will contribute to the improvement of source apportionment in future studies. This work investigates OA, with a focus on primary organic aerosols originated from anthropogenic activities. These scientific findings increase our understanding of OA sources and can help to improve inventories and models as well as to develop plans and policies to mitigate the air pollution in urban environments.
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Oller, Moreno Sergio. "Data processing for Life Sciences measurements with hyphenated Gas Chromatography-Ion Mobility Spectrometry." Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/523539.
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Recent progress in analytical chemistry instrumentation has increased the amount of data available for analysis. This progress has been encompassed by computational improvements, that have enabled new possibilities to analyze larger amounts of data. These two factors have allowed to analyze more complex samples in multiple life science fields, such as biology, medicine, pharmacology, or food science.
One of the techniques that has benefited from these improvements is Gas Chromatography - Ion Mobility Spectrometry (GC-IMS). This technique is useful for the detection of Volatile Organic Compounds (VOCs) in complex samples. Ion Mobility Spectrometry is an analytical technique for characterizing chemical substances based on the velocity of gas-phase ions in an electric field. It is able to detect trace levels of volatile chemicals reaching for some analytes ppb concentrations. While the instrument has moderate selectivity it is very fast in the analysis, as an ion mobility spectrum can be acquired in tenths of milliseconds. As it operates at ambient pressure, it is found not only as laboratory instrumentation but also in-site, to perform screening applications. For instance it is often used in airports for the detection of drugs and explosives. To enhance the selectivity of the IMS, especially for the analysis of complex samples, a gas chromatograph can be used for sample pre-separation at the expense of the length of the analysis.
While there is better instrumentation and more computational power, better algorithms are still needed to exploit and extract all the information present in the samples. In particular, GC-IMS has not received much attention compared to other analytical techniques. In this work we address some of the data analysis issues for GC-IMS: With respect to the pre-processing, we explore several baseline estimation methods and we suggest a variation of Asymmetric Least Squares, a popular baseline estimation technique, that is able to cope with signals that present large peaks or large dynamic range. This baseline estimation method is used in Gas Chromatography - Mass Spectrometry signals as well, as it suits both techniques. Furthermore, we also characterize spectral misalignments in a several months long study, and propose an alignment method based on monotonic cubic splines for its correction. Based on the misalignment characterization we propose an optimal time span between consecutive calibrant samples.
We the explore the usage of Multivariate Curve Resolution methods for the deconvolution of overlapped peaks and their extraction into pure components. We propose the use of a sliding window in the retention time axis to extract the pure components from smaller windows. The pure components are tracked through the windows. This approach is able to extract analytes with lower response with respect to MCR, compounds that have a low variance in the overall matrix
Finally we apply some of these developments to real world applications, on a dataset for the prevention of fraud and quality control in the classification of olive oils, measured with GC-IMS, and on data for biomarker discovery of prostate cancer by analyzing the headspace of urine samples with a GC-MS instrument.Els avenços recents en instrumentació química i el progrés en les capacitats computacionals obren noves possibilitats per l’anàlisi de dades provinents de diversos camps en l’àmbit de les ciències de la vida, com la biologia, la medicina o la ciència de l’alimentació. Una de les tècniques que s’ha beneficiat d’aquests avenços és la cromatografia de gasos – espectrometria de mobilitat d’ions (GC-IMS). Aquesta tècnica és útil per detectar compostos orgànics volàtils en mostres complexes. L’IMS és una tècnica analítica per caracteritzar substàncies químiques basada en la velocitat d’ions en fase gasosa en un camp elèctric, capaç de detectar traces d’alguns volàtils en concentracions de ppb ràpidament. Per augmentar-ne la selectivitat, un cromatògraf de gasos pot emprar-se per pre-separar la mostra, a expenses de la durada de l’anàlisi. Tot i disposar de millores en la instrumentació i més poder computacional, calen millors algoritmes per extreure tota la informació de les mostres. En particular, GC-IMS no ha rebut molta atenció en comparació amb altres tècniques analítiques. En aquest treball, tractem alguns problemes de l’anàlisi de dades de GC-IMS: Pel que fa al pre-processat, explorem algoritmes d’estimació de la línia de base i en proposem una millora, adaptada a les necessitats de l’instrument. Aquest algoritme també s’utilitza en mostres de cromatografia de gasos espectrometria de masses (GC-MS), en tant que s’adapta correctament a ambdues tècniques. Caracteritzem els desalineaments espectrals que es produeixen en un estudi de diversos mesos de durada, i proposem un mètode d’alineat basat en splines cúbics monotònics per a la seva correcció i un interval de temps òptim entre dues mostres calibrants. Explorem l’ús de mètodes de resolució multivariant de corbes (MCR) per a la deconvolució de pics solapats i la seva extracció en components purs. Proposem l’ús d’una finestra mòbil en el temps de retenció. Aquesta millora permet extreure més informació d’analits. Finalment utilitzem alguns d’aquests desenvolupaments a dues aplicacions: la prevenció de frau en la classificació d’olis d’oliva, mesurada amb GC-IMS i la cerca de biomarcadors de càncer de pròstata en volàtils de la orina, feta amb GC-MS.
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Kelly, Van. "Development and application of mass spectrometry based methodologies to study ubiquitin-like modifiers." Thesis, University of Dundee, 2014. https://discovery.dundee.ac.uk/en/studentTheses/e3f36853-fc49-46c2-8b11-f666b33f7f7c.
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Ubiquitin-like proteins (UBLs) have broad activities including modification of proteins, lipids, and tRNA. Analysis of both UBL conjugation sites and characterisation of system wide proteome responses is essential to understanding the impact UBLs have on regulating cellular systems. While mass spectrometry is a powerful analytical technique, identifying UBL isopeptides can be particularly challenging due their low abundance and the spectral complexity of UBL isopeptides with very long tryptic remnants. Furthermore, the complexity of whole proteomes delivers limitations to the throughput and depth of quantitative discovery proteomics. This thesis addresses some of the major technical challenges in UBL research. Biochemical and bioinformatic methodologies have been developed for the selective enrichment proteomics datasets, with a common theme of overcoming proteome complexity. In the first instance, enrichment of diglycine isopeptides has been achieved through a novel method exploiting the polyglycine specificity of the bacterial protease- transpeptidase Sortase A (SrtA). Using a mutant with increased catalytic activity, SrtA mediates biotinylation of diglycine tryptic remnants, and also acts as a specific protease for release of isopeptides from streptavidin for analysis by mass spectrometry. This cost-effective approach to isopeptide enrichment is also applicable to linear N-terminal ubiquitylation. The method is demonstrated to offer greater than 100x enrichment and is exemplified on an in vitro ubiquitylation of MIRO1 by PINK1-activated PARKIN. In contrast to a physical enrichment, a dataset enrichment of isopeptide identifications has been achieved through UBL isotope labelling. In vitro substrate modification with isotopically light and heavy UBL generates a characteristic isotopic doublet enabling isopeptides to be distinguished at the MS1 level. Candidate peptide identity can be assigned using high-resolution precursor mass and complementary MS2- level spectral interpretation with SUMmOn adds further confidence to isopeptide identities. Application to SUMO2 modification of putative substrate RNA guanine-7 methyltransferase (RNMT) revealed widespread SUMOylation at 16 different lysines by UBC9 despite lacking a consensus motif. Finally, a quantitative proteomics workflow is presented that enriches whole proteome datasets by combining peptide identifications from unlabelled and SILAC proteomes. A software implementation, with additional tools for improved data quality management, is demonstrated to significantly improve proteome coverage and quantitative precision in unfractionated proteomes. An exemplification on elp3Δ/wt unfractionated yeast proteome reveals a subset of ELP-dependent uridine-34 tRNA modifications to be particularly important for efficient translation. Interestingly, the three mcm5s2U tRNAs which are co-modified by the UBL URM1, have a much greater impact on protein translation efficiency than the ELP-only modified mcm5U tRNAs.
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Quadri, Syeda. "Metabolomics Investigation of Glyceollins by On-Line Liquid Chromatography-Electrospray Ionization Tandem Mass Spectrometry and Fungal Metabolite Identification by Thermal Desorption Analysis Coupled with Gas Chromatography-Mass Spectrometry." ScholarWorks@UNO, 2013. http://scholarworks.uno.edu/td/1701.
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Metabolomics is an emerging field that entails the detailed characterization of the ensemble of metabolites produced by living organisms; subfields include drug metabolism and natural environmental toxin production. The first part of the dissertation pursued metabolism of glyceollins, i.e., isoflavones produced by soybeans, that are potential cancer therapy agents. In vivo glyceollin metabolites produced in rats were investigated by on-line Liquid Chromatography-Electrospray Ionization Tandem Mass Spectrometry. An odd-electron fragment ion at m/z 148, formed in violation of the even-electron rule, and diagnostic of the glyceollin backbone, was discovered. Based on this finding, a negative mode precursor ion scanning method was developed to screen for glyceollins and their metabolites from biological samples. Products of both Phase I and Phase II metabolism were identified, none of which have been previously reported. Sulfated metabolites were confirmed by accurate mass measurement, while glucuronide conjugation was confirmed by enzyme-assisted glucuronidation by rat liver microsomes. Intact GSH-glyceollin conjugates were not observed, but breakdown products of the GSH pathway, i.e., cysteinylglyceine, cysteine, and acetylated cysteine, were identified as conjugates of oxygenated glyceollins. The identification of GSH by-product conjugates was confirmed in product ion spectra acquired in the negative mode (where peptide anions, and glyceollin-bearing cleaved peptide portions were observed), as well as in the positive mode (where intact oxygenated glyceollin fragments appeared without the initially-present peptide portion). Mass spectral evidence strongly supports a metabolic pathway involving initial epoxidation of glyceollins followed by GSH addition at the epoxidation site.
The second part of the dissertation undertook the investigation of secondary metabolites called microbial volatile organic compounds (MVOCs) produced by fungi (mold) that have been reported to have adverse human health effects. MVOCs were collected onto different sorbent materials and analyzed by Thermal Desorption Analysis coupled with on-line Gas Chromatography-Mass Spectrometry. Fungal MVOCs were characterized from various simulated flooding conditions (brackish, freshwater, and saltwater) and different substrates (nutrient rich vs. low nutrient) to determine diagnostic MVOCs. Ten fungi from simulated environments were identified by genetic sequencing. Cladosporium sp. and Chaetomium sp. were cultivated and their emitted MVOCs, 3-furaldehyde and 3-(4-hydroxy-3-methoxyphenyl)-2-propenal, were proposed as diagnostic indicators of these fungi.
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Metzger, Michael [Verfasser]. "Studies on Fundamental Materials Degradation Mechanisms in Lithium-ion Batteries via On-line Electrochemical Mass Spectrometry / Michael Metzger." München : Verlag Dr. Hut, 2017. http://d-nb.info/1155056302/34.
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Hosu, Ioana Silvia. "Ultrasensitive detection of ricin-like proteins by innovative graphene-based sensors, using mass spectrometry." Thesis, Lille 1, 2020. http://www.theses.fr/2020LIL1I008.
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Les attaques bioterroristes sont devenues plus fréquentes ces dernières années et le large éventail d’agents bioterroristes en fait un problème important à résoudre. La ricine appartient à la famille des protéines inactivant les ribosomes (RIP). Les RIP sont des toxines biologiques, solubles dans l’eau, qui peuvent être facilement extraites de plantes (ricine de Ricinus communis et abrine d’Abrus precatorius) ou de bactéries (toxine de Shiga). La ricine est composée de deux chaînes: la chaîne A de la ricine, une N-glycosidase induisant la toxicité par élimination de l’adénine (action de dépurination) de l’ARNr 28S des sous-unités ribosomales 60S, inhibant la synthèse protéique, et la chaîne B, une lectine qui se lie aux fragments de sucre spécifiques sur la membrane extracellulaire, assurant l'absorption de la toxine. Comme ils inhibent la synthèse des protéines, en fonction de la voie d'absorption et de la dose reçue, la mort peut survenir. En l'absence de contre-mesures efficaces, les méthodes de détection de ces toxines doivent être rapides, fiables, sélectives et sans aucune ambiguïté. Les méthodes actuelles qui sont principalement basées sur des méthodes comme le SERS, l’ELISA, la Colorimétrie et la SPR ne répondent pas à toutes ces exigences. Même si la spectrométrie de masse a été utilisée pour la détection de la ricine, elle ne peut pas être réalisée sans une longue et fastidieuse préparation d'échantillon. Dans ce travail, nous avons montré comment les matériaux à base de carbone (nanomurs de carbone) pourraient être appliqués comme matériaux nanostructurés pour la détection spécifique, rapide et simple de la ricine par désorption/ionisation laser de surface pour la détection par spectrométrie de masse (SALDI-MS). Tout d'abord, l'adéquation des nanoparticules de carbone en tant que bonne surface SALDI a été initialement étudiée pour des biomolécules plus petites. En ce qui concerne les protéines, la littérature a montré qu'elles sont difficiles à ioniser et à détecter avec la méthode SALD-MS, en raison de leur grand poids moléculaire. La capacité des CNWs à désorber et à ioniser les protéines a nécessité de nombreuses étapes d’optimisation. Pour ce faire, le cytochrome C a été utilisé comme protéine modèle. Enfin, des nanomurs de carbone alignés verticalement ont ensuite été modifiés à l'aide de sucres à lectine spécifiques (galactosamine), pour la détection spécifique de la chaîne B de la ricine dans des échantillons réels, tels que des boissons sans alcool et du sérum sanguin. Nous avons obtenu une limite de détection (80 ng/0.5 μL) soit trois fois inférieure à la dose létale médiane la plus faible (DL50 = 10 μg/kg). Cette détection peut être réalisée dans les 10 min. Dans la dernière partie, des résultats préliminaires concernant la mise au point d'outils analytiques bimodaux seront présentés. Il s'agit de combinaisons telles que: SPR (résonance plasmonique de surface)-MS, SERS (Spectroscopie Raman Exaltée de Surface)-MS et EC(Électrochimie)-MS. Une attention particulière a été portée sur la SPR-MS car elle permet d’obtenir des interactions quantitatives et moléculaires en temps réel (SPR) et une identification structurelle des analytes (MS). Les méthodes de dépôt suivantes (de matériaux de type graphène) sont avérées appropriées pour la détection des protéines: la méthode de surfactant à bulle d'oxyde de graphène, le transfert par voie humide de graphène CVD et le dépôt électrophorétique de graphène.Cette thèse décrit pour la première fois le développement d'un capteur de type SALDI-MS, capable de détecter la ricine à une dose inférieure à la dose mortelle chez l'homme et d'apporter ainsi une contribution importante à la lutte contre d'éventuelles attaques terroristes. L'étude systématique de différents paramètres qui influencent ce processus LDI-MS est également présenté. Les techniques bimodales présentent des alternatives intéressantes permettant de créer des outils analytiques plus puissantsBio-terroristic attacks have become more frequent in the past years and the wide range of bio-terroristic agents makes this an important issue to overcome. Ricin is part of the ribosome-inactivating proteins (RIP). RIPs are vegetable toxins, water soluble, which can be easily extracted from plants (ricin from castor beams, abrin from rosary pea) or from bacteria (Shiga toxin). These proteins are composed of two chains: ricin A chain, a glycosidase that insures the toxicity by removal of adenine (depurination) from the RNAr 28S from the 60S ribosomal subunits, followed by the inhibition of protein synthesis, and ricin B chain, a lectin that binds to specific sugar moieties on the surface of the cells, assuring transportation the cell uptake. As they inhibit protein synthesis, depending of the administration take-up (oral, inhalation, intravenously) and the dose received, cell death also occurs. In the absence of efficient counter measurements, detection methods of these toxins have to be fast, reliable, selective and suitable, especially pre-assimilation analysis. The current methods (based on SERS, ELISA, Colorimetric, SPR and MS) do not overcome all these requirements. Even though mass spectrometry was used for ricin detection, it cannot be performed without long and tedious sample preparation. In this work, we describe how carbon-based materials (carbon nanowalls and others) can be used as nanostructured materials for specific, rapid and straightforward ricin-like proteins detection, using surface assisted laser/desorption ionization mass spectrometry (SALDI-MS). The suitability of the carbon nanowalls (CNWS) was proven initially for other smaller bio-molecules.When it comes to proteins, they are hard to ionize and detect using SALD-MS, due in part to their big molecular weight. The ability of CNWs to desorb and ionize proteins required a lot of optimization steps of the SALDI-MS method. A systematic optimization was done using a model protein, the cytochrome C. From this, we were able, for the first time, to detect Ricin B chain without the use of organic matrix. To go further in improving Ricin detection performances, carbon nanowalls were then covalently modified using specific lectin sugars (galactosamine) and the ability to detect Ricin B chain in real samples such as soft drinks and blood serum was demonstrated within10 minutes. We obtained a limit of detection (80 ng/0.5 μL) that is 3 times lower than the lowest median lethal dose (LD50 = 10 μg/kg) Multifunctional surfaces are described as perspectives for more powerful bimodal analytical tools, by combining two techniques, such as: SPR(Surface Plasmon Resonance)/SALDI-MS, SERS(Surface Enhanced Raman Spectroscopy)/SALDI-MS and EC(Electrochemistry)/SALDI-MS. Special attention was focused on SPR/SALDI-MS as it can achieve both quantitative and molecular interactions in real-time (SPR) and precise identification of the analytes (MS). Different depositions methods of graphene-like materials were studied to ensure a good surface coverage of the substrate and the followings methods were suitable for protein detection: bubble surfactant method of graphene oxide, wet transfer of CVD pristine graphene, electrophoretic deposition of graphene.In this thesis, we described the first world wide ricin-like proteins SALDI-MS sensor, which is able to detect below the lethal dose in humans and bring an important contribution to the fight against eventual terroristic attacks. The systematic study of different parameters that influence this LDI-MS process is also presented. The dual surfaces studied, in particular the SPR/MS bimodal techniques, presented reliable consistency for further approaches in creating more powerful analytical tools
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Barks, Hannah Lynn. "Separation and identification of complex mixtures using chromatography mass spectrometry." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33953.
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Here, for the first time, the formation of adenine, hypoxanthine, and guanine from formamide solutions with heating only to 130 degrees C and UV-irradiation in the absence of minerals or inorganic salts is shown using LC-MS/MS as the analysis technique. The thesis goes on to demonstrate that the product distributions change drastically when the temperature is increased to 160 degrees C from 130 degrees C, specifically that the amount of hypoxanthine increases with the addition of UV light, and the amount of adenine increases with an increase in temperature. Along with showing the formation of purines in these reactions, the identification of pyrimidines was also achieved by GCxGC-MS. GCxGC-MS was also used to study additional samples, specifically bio-oils, where the type of compounds in the samples were easily identifiable, which allowed for a direct comparison between different types of bio-oils (e.g. Douglas-fir bark, Southern pine bark, and a Southern pine bark-wood mixture).
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Hosseini, Seyedeh Sona. "Tunable Reflective Spatial Heterodyne Spectrometer| A Technique for High Resolving Power, Wide Field Of View Observation Of Diffuse Emission Line Sources." Thesis, University of California, Davis, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3736922.
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The purpose of this dissertation is to discuss the need for new technology in broadband high-resolution spectroscopy based on the emerging technique of Spatial Heterodyne Spectroscopy (SHS) and to propose new solutions that should enhance and generalize this technology to other fields. Spectroscopy is a proven tool for determining compositional and other properties of remote objects. Narrow band imaging and low resolving spectroscopic measurements provide information about composition, photochemical evolution, energy distribution and density. The extension to high resolving power provides further access to temperature, velocity, isotopic ratios, separation of blended sources, and opacity effects. In current high resolving power devices, the drawback of high-resolution spectroscopy is bound to the instrumental limitations of lower throughput, the necessity of small entrance apertures, sensitivity, field of view, and large physical instrumental size. These limitations quickly become handicapping for observation of faint and/or extended targets and for spacecraft encounters.
A technique with promise for the study of faint and extended sources at high resolving power is the reflective format of the Spatial Heterodyne Spectrometer (SHS). SHS instruments are compact and naturally tailored for both high étendue (defined in section 2.2.5) and high resolving power. In contrast, to achieve similar spectral grasp, grating spectrometers require large telescopes. For reference, SHS is a cyclical interferometer that produces Fizeau fringe pattern for all other wavelengths except the tuned wavelength. The large étendue obtained by SHS instruments makes them ideal for observations of extended, low surface brightness, isolated emission line sources, while their intrinsically high spectral resolution enables one to study the dynamical and physical properties described above.
This document contains four chapters. Chapter 1, introduces a class of scientific targets that formerly have not been extensively observed due to absence of technical capabilities in current apparatus. We will introduce the concept of Special Heterodyne Spectrometers and address how it can fill the gap. Chapter 2 reports on the development of a new mathematical frame work for the Reflective SHS. Chapter 3 provides the details of the design and construction of a Tunable Reflective SHS at both UC Davis laboratory and Mt. Hamilton, Lick Observatory, CA. And chapter 4 contains an overview of the prospects of SHS instruments in future.
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Wang, Zhenyu. "Supercritical Fluid Extraction Directly Coupled with Reversed Phase Liquid Chromatography for Quantitative Analysis of Analytes in Complex Matrices." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/30073.
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The purpose of this research was to design a simple, novel interface for on-line coupling of Supercritical Fluid Extraction (SFE) with High Performance Reversed Phase Liquid Chromatography (HP-RPLC), and to explore its ability for quantitative analysis of analytes in different matrices. First, a simple interface was developed via a single one six-port injection valve to connect the SFE and LC systems. A water displacement method was utilized to eliminate decompressed CO2 gas in the solid phase SFE trap and connection tubes. To evalute this novel hyphenated system, spiked polynuclear aromatic hydrocarbons (PAHs) in a sand matrix were used as target analytes with the achievement of quantitative results. Also PAHs in naturally contaminated soil were successfully extracted and quantitatively determined by this hyphenated system. Compared to the EPA method (Soxhlet extraction followed by GC-MS), on-line SFE-LC gave precise (4-10% RSD) and accurate results in a much shorter time.
Based on this hyphenated technique, a method for the extraction and analysis of hyperforin in St. John's Wort was developed under air/light free conditions. Hyperforin is a major active constituent in the antidepression herbal medicine-Hypericum Perforatum (St. John's Wort). Hyperforin is very sensitive to oxygen and light. There is no way to date to determine whether any degradation occurs during the sample-processing step in the analytical laboratory. On-line coupling of SFE-LC with UV absorbance/ electrospray ionization mass spectrometry (SFE-LC-UV/ESI-MS) provided an air/light free extraction-separation-detection system, which addressed this issue. Mass spectral data on the extract confirmed the presence of the major degradation compounds of hyperforin (i.e. furohyperforin and two of its analogues). Thus, the degradation process must have occurred during plant drying or storage. The feasibility of quantitative extraction and analysis of hyperforin by on-line SFE-LC was made possible by optimizing the extraction pressure, temperature, and modifier content. High SFE recovery (~90%) relative to liquid-solid extraction was achieved under optimized conditions.
We then extended the interface's application to an aqueous sample by using a liquid-fluid extraction vessel. Quantitative extraction and transfer were achieved for the target analytes (progesterone, phenanthrene, and pyrene) spiked in water, as well as in real samples (urine and environmental water). During each extraction, no restrictor plugging was realized. Extraction temperature and pressure were optimized. Different amounts of salt were added to the aqueous matrix to enhance ionic strength and thus extraction efficiency. Methanol and 2-propanol were used as CO2 modifiers. Two modifier modes were compared, e.g. dynamically mixing modifier with the CO2 extraction fluid, and pre-spiking modifier in the extraction vessel. Surprisingly, we found pre-spiking the same amount of modifier in the vessel enhanced the recovery from ~70% to ~100% for progesterone, phenanthrene, and pyrene due to a "co-extraction effect".
The last phase of our work explored the disadvantages/limitations of this hyphenated technique through the analysis of more highly polar phenolic compounds in grape seeds. Five types of SFE trapping adsorbent materials were evaluated in an effort to enhance the collection efficiency for the polar components. Pure supercritical CO2 was used first to remove the less polar oil in the seeds. Then methanol-modified CO2 was used to remove the polar components (e.g. phenolic compounds). Catechin and epicatechin (90%) were exhaustively extracted out of the de-oiled seed after 240 minutes with 40% methanol as modifier. Both singly linked (B-type) and doubly linked (A-type) procyanidins were identified by LC-ESI-MS, as well as their galloylated derivatives. Compared to the off-line SFE-LC approach, much less sample was required for extraction in the on-line method, since all the extracted components could be transferred to the LC column. Also, no extract processing/concentration step was needed in the on-line method. However, in the on-line mode, some polar compounds were lost (1) during the collection step (e.g. lower trapping efficiency on a single solid SFE trap when a high percentage modifier was used) and (2) during the water rinsing step (e.g. less retention of polar compounds on C18 trap). Therefore, this hyphenated technique is less desirable for the analysis of highly polar compounds.Ph. D.
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Eyglunent, Grégory. "TDCIAMS (Thermal Desorption Chemical Ionization Aerosol Mass Spectrometer) : Analyse en ligne de l'Aérosol Organique - développement et applications." Phd thesis, Université de Provence - Aix-Marseille I, 2007. http://tel.archives-ouvertes.fr/tel-00182294.
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Cette étude s'inscrit dans une problématique globale d'analyse en ligne de la composition chimique de l'Aérosol Organique Secondaire (AOS) pour une meilleure compréhension de sa formation et de son vieillissement, à travers le développement d'un spectromètre de masse à désorption thermique et ionisation chimique : le TDCIAMS. La caractérisation des performances de cet instrument, ainsi que l'étude de l'AOS formé par ozonolyse de l'a- pinène en chambre de simulation atmosphérique (CSA) ont montré que le TDCIAMS est bien adapté à l'analyse quantitative de l'AOS formé en CSA. Les données recueillies par le TDCIAMS permettent d'accéder à des informations essentielles concernant les mécanismes de formation et l'évolution de l'AOS. De plus, l'étude de l'AOS formé par ozonolyse de deux composés d'origine anthropique (2-méthylstyrène et indène), peu étudiés jusqu'alors, a été comparée avec celle réalisée par une analyse off-line (SFE-GC-MS).
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Sarda, Estève Roland. "Étude de la variabilité des bioaérosols atmosphériques en région île de France." Electronic Thesis or Diss., université Paris-Saclay, 2021. http://www.theses.fr/2021UPASJ004.
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Les bioaérosols atmosphériques sont des particules d’aérosols biologiques primaires en suspension dans l’air et référencés dans la littérature comme étant des: Primary Biological Aerosol Particles (PBAPs). Les PBAPs sont de tailles et de natures très différentes. Ils ont la capacité à agir comme noyaux de condensation nuageux ou de glace et participent ainsi au cycle de l’eau sur terre. Ils peuvent être transportés loin de leur zone d’émission et coloniser de nouveaux écosystèmes. Leur caractère allergisant ou pathogène a un impact sur la santé humaine et animale. Ce travail de thèse qui porte sur l’étude de la variabilité des bioaérosols atmosphériques en région île de France concerne les pollens, les moisissures et les bactéries. Les observations ont été réalisées dans la couche limite à l’observatoire du SIRTA/LSCE. Ce travail pionnier dans la région Francilienne a permis: (1) de documenter la variabilité interannuelle, saisonnière et journalière propre à chacun des PBAPs, (2) de déterminer leurs origines géographiques respective, (3) d’étudier les paramètres météorologiques qui gouvernent leur cycle de vie dans l’atmosphère. Mon dernier objectif (4) a été de developper un instrument de mesure en temps reel des PBAPs et plus specifiquement des pollensAtmospheric bioaerosols are particles of primary biological aerosols suspended in the air and referred in the literature as: Primary Biological Aerosol Particles (PBAPs). PBAPs have very different sizes and coposition. They have the ability to act as cloud condensation nuclei or ice nuclei and thus participate in the water cycle on earth. They can be transported far from their sources and they can in this way colonize new ecosystems. Their allergenic or pathogenic propoeries have an impact on human and animal health. This work on the variability of atmospheric bioaerosols in the Ile de France region concerns pollens, molds and bacteria. The observations were made in the boundary layer at the SIRTA/LSCE observatory. This pioneering work in the Ile-de-France region had the objective to: (1) document the interannual, seasonal and daily variability specific to each of the PBAPs, (2) determine their respective geographical origins, (3) study the meteorological parameters that control their life cycle in the atmosphere. My last objective (4) has been to develop an on line instrumenst to measure in real time BPAPs concentrations with a focus on pollen
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Korkmaz, Deniz. "Preconcentration Of Volatile Elements On Quartz Surface Prior To Determination By Atomic Spectrometry." Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12604921/index.pdf.
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Hydride generation technique is frequently used for the detection of elements as As, Se, Sb, Sn, Bi, Ge, Te and Pb that form volatile hydrides in solution using a reductant. In this study, a novel quartz trap for on-line preconcentration of volatile analyte species was designed. Pb, Sb and Cd were selected as analyte elements and chemical vapour generation technique was employed for generation of their volatile species in flow systems. The trapping medium was formed by external heating of either the inlet arm of the quartz tube atomizer or a separate cylindirical quartz tube. Generated analyte species were trapped on quartz surface heated to the collection temperature and the collected species were revolatilized when the trap was heated further to releasing temperature and hydrogen gas was introduced in the trapping medium. The conventional quartz T-tube and multiple microflame quartz tube were employed as atomizers. The influence of relevant experimental parameters on the generation, collection and revolatilization efficiencies was investigated. Optimum conditions, performance characteristics of the trap and analytical figures of merit are presented. Experimental design was used for optimizations in some cases. Standard reference materials were analyzed to assess the accuracy of the proposed method. For a collection period of 1.0 minute for Pb, 2.0 minutes for Sb and 3.0 minutes for Cd, 3σ
limit of detections, in pg ml-1, were 19, 3.9 and 1.8, respectively. In cases of Sb and Cd, the limits of detections obtained are the same as the best attained with in-situ trapping in graphite furnaces.
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Cankur, Oktay. "On-line Preconcentration Of Vapor Forming Elements On Resistively Heated W-coil Prior To Their Determination By Atomic Absorption Spectrometry." Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605049/index.pdf.
Full textAbstract:
Vapor generation in atomic spectrometry is a well established technique for the
determination of elements that can be volatilized by chemical reactions. In-situ
trapping in graphite furnaces is nowadays one of the most popular methods to
increase the sensitivity. In this study, resistively heated W-coil was used as an online
trap for preconcentration and revolatilization of volatile species of Bi, Cd and
Pb. The collected analyte species were revolatilized rapidly and sent to a quartz Ttube
atomizer for AAS measurement. Although the nature of revolatilized species
of Bi and Pb are not clear, they are probably molecular since they can be
transported at least 45 cm without any significant decrease in the peak height
values. However, cadmium is revolatilized from the trap surface as atoms.
The experimental parameters were optimized for the highest vapor generation,
trapping and revolatilization efficiencies. The concentration limits of detection
calculated by the 3 of blank solution were found to be 0.0027, 0.0040 and 0.015
ng/mL for Bi (18 mL), Cd (4.2 mL) and Pb (2 mL), respectivelyenhancement factors in the sensitivity were 130, 31 and 20, respectively. These values are comparable with those obtained by in-situ trapping in graphite furnaces or even ICP-MS found in the literature or better. Sensitivity can be improved further for Bi and Cd using larger sample volumes, but purification of blank is required for Pb. Certified standard reference materials were analyzed for the assessment of accuracy of developed method.
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Akay, Pinar. "Inorganic Antimony Speciation Using Tungsten Coil Atom Trap And Hydride Generation Atomic Absorption Spectrometry." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12611543/index.pdf.
Full textAbstract:
Antimony is a toxic element which is mostly found in two oxidation states (III and V) in environmental, biological and geological samples. Antimony may form various inorganic and organic compounds that exhibit differences in analytical behavior, toxicity and mobilityinorganic compounds of antimony are more toxic than organic forms and toxicity of Sb(III) has been shown to be 10 times higher than that of Sb(V). Therefore selective determination of Sb(III) and Sb(V) is required in environmental and biological samples. Hydride generation atomic absorption spectrometry is a sensitive, fast and economical technique for the determination of antimony at trace level. A possible non-chromatographic method for antimony speciation is hydride generation atomic absorption spectrometry that is based on the relatively slow kinetics of hydride formation from Sb(V). In this study, continuous flow hydride generation method for the determination of antimony was developed and hydride generation conditions were optimized. Analyte solution was prepared in 0.050 mol/L HCl and 1.2% (w/v) NaBH4 stabilized in 0.30% (w/v) NaOH was used as a reductant solution. Inorganic antimony speciation conditions were determined by continuous flow HGAAS system. For the pre-reduction of Sb(V) to Sb(III), 8.0% (w/v) potassium iodide (KI) and 0.10% (w/v) ascorbic acid were used. Further speciation study was also carried out using Ir coated W-coil Atom Trap Hydride Generation Atomic Absorption Spectrometry. Tungsten coil atom trap was used to enhance the sensitivity. Tungsten coil surface was treated with Ir and totally 250 &
#956
g 1000 mg/L Ir stock solution was used for coating of tungsten coil. LOD and LOQ values were calculated as 152 pg/mL and 508 pg/mL according to 120 seconds trapping. 128 and 37 fold enhancement were obtained for 120 seconds collection with respect to W-coil-ETAAS and ETAAS, respectively.
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Harper, Carla Jo. "Development and application of an on-line liquid chromatography interface for the analysis of biomolecules by Fourier transform ion cyclotron resonance mass spectrometry /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Wang, Tao-Chin Lin. "Part I: Dispersion versus absorption (DISPA) line shape analysis. Part II: Ion trajectories and excitation techniques in fourier transform ion cyclotron mass spectrometry /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487260135355759.
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Schweitzer, Mario. "Optical Alignment and Characterization of FIFI-LS - the Far-Infrared Field Imaging Line Spectrometer for SOFIA and Spitzer IRS Observations of Active Galaxies." Diss., lmu, 2008. http://nbn-resolving.de/urn:nbn:de:bvb:19-87542.
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Forsgard, Niklas. "Inductively Coupled Plasma Spectrometry for Speciation Analysis : Development and Applications." Doctoral thesis, Uppsala universitet, Analytisk kemi, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8169.
Full textAbstract:
In analytical chemistry the main goal is normally to determine the identity and/or concentration of one or more species in a sample. The samples analyzed are often natural samples, containing numerous different species in a complex matrix and the choice of technique for multi-elemental detection is in general inductively coupled plasma spectrometry. The chemical forms of an element can affect many of its characteristics e.g. toxicity, which makes speciation analysis important. Therefore, determination of the identity and quantity of an element is still important, but for many applications measurements of total element concentration provides insufficient information. To be able to perform speciation analysis, separation, identification and/or characterization of the various forms of elements in the sample has to be accomplished. Speciation analysis has been employed in a wide range of disciplines, including for example environmental science, biology and clinical chemistry. This thesis describes work to improve and understand the elemental speciation analysis with liquid chromatography coupled to plasma spectrometry and also highlights the importance and potential of the synergy between atomic spectrometry and molecular mass spectrometry. The combination of the matrix tolerant, robust and very sensitive plasma spectrometry used together with molecular mass spectrometry, which provides structural information and the possibility to identify unknown species, is demonstrated to be a very powerful tool for speciation analysis. In this thesis methods are developed for on-line sample clean-up and pre-concentration coupled to liquid chromatography and plasma spectrometry, which makes handling of small sample volumes easier and also decreases the risk of contamination. The problems associated with organic modifiers in plasma spectrometry are also addressed. Applications of speciation analysis are exemplified by analysis of aluminium-chelated siderophores in field-soil solutions and organic phosphorous species in aquatic sediments. The possibility to analyze un-dissolved samples as slurries with minimal sample preparation is also discussed.
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Colditz, Sebastian [Verfasser]. "FIFI-LS – A Field-Imaging Far-Infrared Line Spectrometer for SOFIA: Completion of the Instrument, Laboratory and In-flight Calibration and Characterization / Sebastian Colditz." München : Verlag Dr. Hut, 2017. http://d-nb.info/1140978055/34.
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Park, Sinyoung. "Mammalian cell respiration and oxygen and carbon dioxide transfer in high-density perfusion culture with microsparge oxygenation and on-line mass spectrometry /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
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Chicooree, Navin. "Enhancing the mass spectrometric analysis of ubiquitin-like modifications." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/enhancing-the-mass-spectrometric-analysis-of-ubiquitinlike-modifications(ab42ea7c-73d1-4348-85e5-69813be451f7).html.
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Mamalian protein ubiquitination and SUMOylation are reversible post translational modifications, which are involved in a multitude of important complex regulatory processes within the cell. Current mass spectrometry approaches that involve bottom-up proteomics to comprehensively analyse these modifications, have proved to be problematic. In this work, analytical approaches are carried out to improve and enhance the comprehensive analysis of these modifications. Tryptic proteolysis of ubiquitinated proteins results in the generation of isopeptides bearing adi-glycine (GG) remnant. Current mass spectrometry approaches used to identify these isopeptides are predominantly reliant on detecting the signature mass shift of the GG remnant (114.043 Da). The lack of sequence information from the GG remnant post MS/MS acquisition results in database search algorithms falsely identifiying these isopeptides. Reductive methylation chemistry was employed to derivatize these isopeptides. Upon collision induced dissociation of the isopeptides two robust ions were released from the iso-N-terminus of the GG remnant ; i) an a1’ ion at m/z 62.09, corresponding to the G of the remnant and ii) a b2’ ion at m/z 147.11, corresponding to the full GG remnant. Post-acquisition data extraction of these unique diagnostic ions demonstrated enhanced selectivity towards identifying these isopeptides. Tryptic proteolysis of SUMOylated proteins results in the generation of isopeptides bearing a substantial iso-C-terminal SUMO remnant. The CRA(K) (Consecutive Residue Addition tolysines (K)) approach combined independant use of proteolytic enzymes and unbiased consecutive residue addition of amino acids pertaining to these iso-C-terminal SUMOremnants, on all lysine residues. This approach enabled the identification of analytically useful novel wildtype isopeptides derived from the proteolysis of SUMO(1/2/3)ylated proteins, bearing GG, TGG and QTGG remnants. The analytically useful isopeptides derived from proteolysis of SUMO(2/3)ylated proteins lacked robust diagnostic information from their iso-C-terminal bearing TGG and QTGG remnants. Reductive methylation chemistry was utilised to derivatize these isopeptides and enabled diagnostic a’ and b’ ions to be released from their iso-N-termini; i) a1’ (m/z 133.13),b2’ (m/z 262.17) and b4’ (m/z 376.22) ions, corresponding to the QTGG remnant and ii) (m/z106.10), b2’ (m/z 191.14) and b3’ (m/z 248.14) ions, corresponding to the TGG remnant. Post-acquisition data extraction of these unique diagnostic ions, enabled comprehensive structural elucidation of these isopeptides and enhanced selectivity towards identification.
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Myers, Alexandra. "Identification of CaMK-II Protein Targets in Tissue Culture and Zebrafish Embryos using Tandem Mass Spectrometry." VCU Scholars Compass, 2009. http://scholarscompass.vcu.edu/etd/10.
Full textAbstract:
Calcium (Ca2+)/calmodulin-dependent kinase 2 (CaMK-II) is one member of a family of Ca2+/calmodulin-dependent protein kinases that responds to intracellular Ca2+ signals (Hudmon, A. and H. Schulman (2002)). CaMK-II is a multifunctional regulator of transcription, cell cycle progression, cell motility and neuronal development. (Wang, C., et al. (2008), Easley, C. A. IV, et al. (2008), Osterhoff, M., et al. (2003), Faison, M. O., et al. (2002)). Recently, CaMK-II has been shown to be important in the early development of vertebrates. In developing zebrafish, disruption of CaMK-II expression has been shown to induce phenotypes similar to those documented in several human diseases. The identification of the tissue-specific binding partners and substrates of CaMK-II which are responsible for specific developmental fates remains a key step in understanding this important protein kinase family. In this thesis research, specific “substrate-trapping” mutants of CaMK-II were designed, introduced into a variety of rodent and human cell lines in culture and used in conjunction with tandem mass spectrometry to identify binding partners, such as β-actin, tropomodulin-3 and Fli-I as well as novel, putative substrates, such as the tumor suppressor protein 53 (p53). This approach was subsequently applied to zebrafish embryos where an overlapping subset of CaMK-II binding proteins to those found in mammalian cell culture were identified. This project represents one of the first studies to identify binding proteins in zebrafish embryos using epitope tagging and mass spectrometry. This research has also established a technical framework for the use of mass spectrometry to characterize the developmental proteome of whole zebrafish embryos or specific zebrafish tissues at any developmental time point.
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Earle, Lieko. "Z-Spec: A broadband spectrometer for millimeter-wave astrophysics---Instrument development and results of a molecular line survey of nearby star-forming galaxy NGC 253." Connect to online resource, 2008. 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:3337091.
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Evers, Frank Richard. "Development of a liquid chromatography ion trap mass spectrometer method for clinical drugs of abuse testing with automated on-line extraction using turbulent flow chromatography." Thesis, University of Portsmouth, 2014. https://researchportal.port.ac.uk/portal/en/theses/development-of-a-liquid-chromatography-ion-trap-mass-spectrometer-method-for-clinical-drugs-of-abuse-testing-with-automated-online-extraction-using-turbulent-flow-chromatography(c047da7d-eb8a-41d0-ad1c-830deca531dc).html.
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Aims The method for the confirmation of drugs of abuse for addiction testing within King’s College Hospital prior to 2008 was a labour intensive thin layer chromatography method. To replace this with a faster method more suited to future requirements, the laboratory bought a liquid chromatography system with ion trap mass spectrometric detection. The development of the routine analytical method and the implementation of this method within the laboratory using on-line solid phase extraction and Turboflow® sample preparation will allow the laboratory to operate successfully in the field of clinical drugs of abuse testing in the future. Method Analyses are performed on an ion trap mass spectrometer with an electrospray ion source following reversed phase liquid chromatography, initially using on-line solid phase extraction with a Jasco XLC® series autosampler and pump and later a Thermo Turboflow® on-line extraction method with a CTC Combi-Pal® autosampler and Agilent 1100 series liquid chromatography system. Elution of drugs and metabolites is performed with a multi-step gradient of ammonium formate buffer and acetonitrile, followed by regeneration of the extraction and analytical columns to starting conditions. Detection is achieved with a Thermo LCQ Fleet ion trap mass spectrometer with a combination of full spectrum survey scans, dedicated product ion scans, neutral loss scans and data dependent product ion scans in two analysis segments. Total run time is only 20 minutes, allowing a throughput of around 65 samples per day. Results The methods include the novel combination of the elimination of any hydrolysis step, on-line SPE or Turboflow extraction, detection of multiple drug groups, full spectrum analysis and library matching, the use of data dependent scans and ion trap mass spectrometry using MS3 and neutral loss scans. The methods developed were validated using a departmental method validation protocol and accepted for routine use. Simultaneous detection of over fifty analytes has been found possible in a range of clinically relevant drug groups, including opiates, amphetamines, methadone, propoxyphene, cocaine, ketamine and their metabolites. The use of neutral loss scans and product ion scans of phase 2 drug metabolites permits the addition of previously unidentified drugs and metabolites to the method, allowing the laboratory’s services to develop in line with requirements of the service. Quality is maintained through the use of standard operating procedures, staff training, quality control samples and external quality assessment. Conclusion Drugs of abuse testing is key for treatment and monitoring of drug addiction. The introduction of modern mass spectrometry techniques has reduced the turnaround time of routine analysis for a range of drugs and metabolites and increased the range of drugs that can be analysed. The methods introduced have revolutionised testing at King’s College Hospital and produced a method which is capable of evolving with the needs of the service to keep abreast of future requirements of the service.
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Krishnaswamy, Sangeetha. "Kinetics of volatile generation during coffee roasting and analysis using Selected Ion Flow Tube-Mass Spectrometry." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492506642418004.
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Wetterhall, Magnus. "Electrifying the Molecules of Life : Peptide and Protein Analysis by Capillary Electrophoresis Coupled to Electrospray Ionization Mass Spectrometry." Doctoral thesis, Uppsala University, Department of Chemistry, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4233.
Full textAbstract:
This thesis describes the current status and novel aspects of the analysis of the molecules of life, i.e. peptides and proteins, using capillary electrophoresis (CE) coupled to mass spectrometry (MS) via (sheathless) electrospray ionization (ESI). Early reports of sheathless CE-ESI-MS were plagued by limited lifetimes of the electrospray emitter. In this thesis, two new approaches, the Black Dust and the Black Jack methods, utilizing polymer-embedded graphite instead of noble metals are presented. These emitters have shown improved long-term stability and proven excellent for sheathless electrospray operation. Failure of an emitter is often caused by electrochemical reactions occurring at the emitter-liquid interface. The electrochemical properties of the graphite coated emitters were therefore evaluated by classical electrochemical methods, such as cyclic voltammetry and chronoamperometry. The graphite coated emitters showed excellent electrochemical stability and properties compared to noble metal and polymer configurations.
Analyte-wall interactions have long been known to cause problems in the CE analysis of biomolecules. This can be circumvented by internal modification of the capillary walls. Additionally, it is of outermost importance to have a stable and sufficiently high electroosmotic flow (EOF) to sustain the electrospray, when using a sheathless approach. New monomer and polymer coatings are presented for rapid and high-efficient CE-ESI-MS separations of peptides and proteins.
Furthermore, the use of CE-ESI coupled to Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS) shows great potential for rapid proteomic probing of human cerebrospinal fluid. The results are comparable with more established techniques, such as liquid chromatography and two-dimensional gel electrophoresis coupled to MS. However, the CE-ESI-FTICRMS analysis has significantly lower sample consumption and faster analysis time compared to the other techniques. The applications and use of CE-ESI-MS is expected to have a bright future with continued growth as current trends of multidimensional hyphenation and microfabricated devices are further developed and explored.