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Littérature scientifique sur le sujet « Mass Spectrometry technique »

Auteur : Grafiati
Publié le 9 mars 2023
Mis à jour le 10 mars 2023

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Articles de revues sur le sujet "Mass Spectrometry technique"

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R Swetha Sri, B Aishwarya, D Vaishnavi et M Sumakanth. « A review on ion mobility mass spectrometry ». Open Access Research Journal of Biology and Pharmacy 6, no 2 (30 novembre 2022) : 013–23. http://dx.doi.org/10.53022/oarjbp.2022.6.2.0067.

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Mass Spectrometry can be coupled with ion mobility to get results that cannot be obtained by alone mass spectrometry. This coupled instrument can be used for knowing the separation of isomers, isobars, and conformers, the reduction of chemical noise, and the measurement of ion size. It divides ions into families of ions as well as ions with the same charge and similar structural properties. The four ion mobility separation techniques currently applied to mass spectrometry are described in this article. Low-resolution mobility separation is demonstrated by AIMS. Offering continuous ion monitorings are DMS and FAIMS. TWIMS is a novel IMS technique that has good sensitivity and is well integrated into a commercial mass spectrometer while having modest resolving power. In this review it includes that Many researches has used this technique has it gives results in millisecond and its low cost operation.it has major drawback of contamination of compounds due to atmospheric pressure, complex spectra and interferences aredue to wide spread of ionization.it is not suitable for Non-volatile compound and the repoducubility is1-2%.
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Niwa, Toshimitsu, et Akira Shimizu. « New challenge of mass spectrometry technique ». Journal of Chromatography B 855, no 1 (août 2007) : 1. http://dx.doi.org/10.1016/j.jchromb.2007.02.051.

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Chan, Daniel Shiu-Hin, Andrew J. Whitehouse, Anthony G. Coyne et Chris Abell. « Mass spectrometry for fragment screening ». Essays in Biochemistry 61, no 5 (6 octobre 2017) : 465–73. http://dx.doi.org/10.1042/ebc20170071.

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Fragment-based approaches in chemical biology and drug discovery have been widely adopted worldwide in both academia and industry. Fragment hits tend to interact weakly with their targets, necessitating the use of sensitive biophysical techniques to detect their binding. Common fragment screening techniques include differential scanning fluorimetry (DSF) and ligand-observed NMR. Validation and characterization of hits is usually performed using a combination of protein-observed NMR, isothermal titration calorimetry (ITC) and X-ray crystallography. In this context, MS is a relatively underutilized technique in fragment screening for drug discovery. MS-based techniques have the advantage of high sensitivity, low sample consumption and being label-free. This review highlights recent examples of the emerging use of MS-based techniques in fragment screening.
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Szpunar, J., et R. Lobinski. « Species-selective Analysis for Metal - Biomacromolecular Complexes using Hyphenated Techniques ». Pure and Applied Chemistry 71, no 5 (30 mai 1999) : 899–918. http://dx.doi.org/10.1351/pac199971050899.

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Analytical chemistry of metal complexes with biomacromolecules based on the coupling of a high resolution separation technique with an element or species selective detection technique is critically discussed. The role of size-exclusion chromatography (SEC) with on-line atomic spectrometric detection is evaluated for the characterization of the metal distribution among the fractions of different molecular weight. Attention is given to the conditions for the separation of metallated biomacromolecular isoforms and sub-isoforms by anion-exchange and reversed-phase HPLC. Techniques for interfacing chromatography with atomic absorption spectrometry (AAS), inductively coupled plasma atomic emission spectrometry (ICP AES) and ICP mass spectrometry (ICP MS) are assessed. The potential of electrospray (tandem) mass spectrometry for the on-line determination of the molecular mass of the eluting protein is highlighted. Perspectives for capillary zone electrophoresis (CZE), microbore and capillary HPLC with ICP MS and electrospray MS detection for probing metalloproteins are discussed. Applications of hyphenated techniques to the analysis of real-world samples are reviewed.
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Davies, S., J. A. Rees et D. L. Seymour. « Threshold ionisation mass spectrometry (TIMS) ; a complementary quantitative technique to conventional mass resolved mass spectrometry ». Vacuum 101 (mars 2014) : 416–22. http://dx.doi.org/10.1016/j.vacuum.2013.06.004.

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Termopoli, Veronica, Maurizio Piergiovanni, Davide Ballabio, Viviana Consonni, Emmanuel Cruz Muñoz et Fabio Gosetti. « Condensed Phase Membrane Introduction Mass Spectrometry : A Direct Alternative to Fully Exploit the Mass Spectrometry Potential in Environmental Sample Analysis ». Separations 10, no 2 (17 février 2023) : 139. http://dx.doi.org/10.3390/separations10020139.

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Membrane introduction mass spectrometry (MIMS) is a direct mass spectrometry technique used to monitor online chemical systems or quickly quantify trace levels of different groups of compounds in complex matrices without extensive sample preparation steps and chromatographic separation. MIMS utilizes a thin, semi-permeable, and selective membrane that directly connects the sample and the mass spectrometer. The analytes in the sample are pre-concentrated by the membrane depending on their physicochemical properties and directly transferred, using different acceptor phases (gas, liquid or vacuum) to the mass spectrometer. Condensed phase (CP) MIMS use a liquid as a medium, extending the range to new applications to less-volatile compounds that are challenging or unsuitable to gas-phase MIMS. It directly allows the rapid quantification of selected compounds in complex matrices, the online monitoring of chemical reactions (in real-time), as well as in situ measurements. CP-MIMS has expanded beyond the measurement of several organic compounds because of the use of different types of liquid acceptor phases, geometries, dimensions, and mass spectrometers. This review surveys advancements of CP-MIMS and its applications to several molecules and matrices over the past 15 years.
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Vidová, Veronika, Michael Volný, Karel Lemr et Vladimír Havlíček. « Surface analysis by imaging mass spectrometry ». Collection of Czechoslovak Chemical Communications 74, no 7-8 (2009) : 1101–16. http://dx.doi.org/10.1135/cccc2009028.

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A review of four MS-based techniques available for molecular surface imaging is presented. The main focus is on the commercially available mass spectrometry imaging techniques: secondary ion mass spectrometry (SIMS), matrix assisted laser desorption ionization mass spectrometry (MALDI-MS), desorption electrospray ionization mass spectrometry (DESI-MS) and laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS). A short historical perspective is presented and traditional desorption ionization techniques are also briefly described. The four techniques are compared mainly with respect to their usage for imaging of biological surfaces. MALDI is evaluated as the most successful in life sciences and the only technique usable for imaging of large biopolymers. SIMS is less common but offers superior spatial lateral resolution and DESI is considered to be an emerging alternative approach in mass spectrometry imaging. LA-ICP ionization is unbeatable in terms of limits of detection but does not provide structural information. All techniques are considered extremely useful, representing a new wave of expansion of mass spectrometry into surface science and bioanalysis. A minireview with 121 references.
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Woehlck, Harvey J., Marshall Dunning, Kasem Nithipatikom, Alexander H. Kulier et Daniel W. Henry. « Mass Spectrometry Provides Warning of Carbon Monoxide Exposure Via Trifluoromethane ». Anesthesiology 84, no 6 (1 juin 1996) : 1489–93. http://dx.doi.org/10.1097/00000542-199606000-00026.

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Background The chemical breakdown of isoflurane, enflurane, or desflurane in dried carbon dioxide absorbents may produce carbon monoxide. Some mass spectrometers can give false indications of enflurane during anesthetic breakdown. Methods During clinical anesthesia with isoflurane or desflurane, the presence of carbon monoxide in respiratory gas was confirmed when enflurane was inappropriately indicated by a clinical mass spectrometer that identified enflurane at mass to charge ratio = 69. In vitro, isoflurane, enflurane, or desflurane in oxygen was passed through dried carbon dioxide absorbents at 35, 45, and 55 degrees C. Gases were analyzed by gas chromatography and by mass spectrometry. Results Mass spectrometry identified several clinical incidents in which 30-410 ppm carbon monoxide was measured in respiratory gas. Trifluoromethane was produced during in vitro breakdown of isoflurane or desflurane. Although these inappropriately indicated quantities of "enflurane" correlated (r2 > 0.95) to carbon monoxide concentrations under a variety of conditions, this ratio varied with temperature, anesthetic agent, absorbent type, and water content. Conclusions Trifluoromethane causes the inappropriate indication of enflurane by mass spectrometry, and indicates isoflurane and desflurane breakdown. Because the ratio of carbon monoxide to trifluoromethane varies with conditions, this technique cannot be used to quantitatively determine the amount of carbon monoxide to which a patient is exposed. If any warning of anesthetic breakdown results from this technique then remedial steps should be taken immediately to stop patient exposure to carbon monoxide. No warning can be provided for the breakdown of enflurane by this technique.
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Bhole, R. P., S. R. Jagtap, K. B. Chadar et Y. B. Zambare. « Liquid Chromatography-Mass Spectrometry Technique-A Review ». Research Journal of Pharmacy and Technology 13, no 1 (2020) : 505. http://dx.doi.org/10.5958/0974-360x.2020.00097.9.

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Satoh, Takaya, Kentaro Takahara, Tomoaki Kondo, Ryo Ogasawara et Chika Nogami. « Recent data analysis technique in mass spectrometry ». Japanese Journal of Pesticide Science 42, no 1 (2017) : 203–15. http://dx.doi.org/10.1584/jpestics.w17-54.

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Thèses sur le sujet "Mass Spectrometry technique"

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Collin, Olivier L. « Development of a Novel Tandem Mass Spectrometry Technique for Forensic and Biological Applications ». View abstract, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3292877.

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COGHI, MARIA DONATA. « Samdi mass spectrometry for high yield protein modification reaction development ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2014. http://hdl.handle.net/10281/50887.

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Efficient chemical strategies that attach synthetic molecules to desired positions on protein surfaces are useful tools in the field of chemical biology and represent one major prerequisite for the development of new drugs and materials. Protein modification with polyethylene glycol (PEG) groups is indeed routinely performed on therapeutic proteins to improve serum half-life, or even cytotoxins or imaging agents are efficiently conjugated to cancer-targeting elements. In a typical approach, a synthetic functional group of interest is attached to a uniquely reactive amino acid group introduced by recombinant methods. Most bioconjugation reactions, however, do not reach full conversion. Therefore the development of a straightforward and reliable method to increase the extent of conversion into bioconjugates would be very helpful. In this perspective, we developed a generalizable combinatorial peptide library screening platform suitable for the identification of sequences displaying high levels of reactivity toward a desired bioconjugation reaction. This was achieved by using SAMDI MS technique (Self-Assembled Monolayer and Desorption/Ionization Mass Spectrometry) as a new, efficient and simple method for the evaluation of highly reactive amino acid motifs. The bioconjugation reaction we selected is the oxidative modification of electron-rich tyrosine residues performed using cerium(IV) ammonium nitrate (CAN) as oxidant reagent. The peptides were identified on a 361-member hexapeptide array, wherein the two N- and C-terminal residues to the target residue were varied. The arrays were prepared by immobilizing the peptides to a self-assembled monolayer of alkanethiolates on gold and could therefore be analyzed by mass spectrometry. We found that the most reactive peptides had either a serine N-terminal to the tyrosine residue or another tyrosine in proximity of the reactive site. Conversely, peptides displaying the lowest conversion level contained a positive charged residue: histidine, lysine or arginine, where the lowest relative activity was reached with arginine and leucine as C- and N- terminal residues, respectively. This study provides an important example of how synthetic peptide libraries can accelerate the discovery and optimization of protein bioconjugation strategies.
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Sproch, Norman K. « Electrospray mass spectrometry : an investigation of non- covalent interactions of cytochrome c/crown ether complexes and applied methods of computational chemistry ». Virtual Press, 1994. http://liblink.bsu.edu/uhtbin/catkey/917033.

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This research is directed at developing the interplay of experimental and computational methods in the area of biochemical mass spectrometry. The experimental method is that of electrospray ionization mass spectrometry (ESI-MS). The computational methods employed are those of semi-empirical quantum mechanics and molecular modeling.The use of Electrospray Mass Spectrometry was developed to investigate whole proteins and the non-covalent complexes that may be formed with small molecules. This method provides the soft ionization needed to accurately determine a noncovalently bound complex's mass with an error of less than 0.1 %. An original design electrospray ionization source (ESI) and a syringe pump have been built to fulfill the goals of the research. The ESI source design has been published in The Journal of the American Society for Mass Spectrometry, (1993, 4, 964-967).In this work the protein selected was cytochrome c and its variants from different species. The small molecules chosen were a broad class of structures known as crown ethers. With the ESI technique the proteins are prepared in an acidic solution that fully protonates the solvent-exposed basic amino acid residues. This provides the protein with many positive charges which makes the analysis by ESI mass spectrometry possible with a single quadrupole instrument, an Extrel ELQ 400. The mass of the protein is divided by the number of positive charges. The small molecules, the crown ethers, were chosen due to their ability to bind ammonium ion and protonated amino groups. This binding is non-covalent, hydrogen bonds stabilize the complex formation. Because this complex is non-covalent in nature the charge of proteins does not change. To aid in the interpretation of our electrospray mass spectra we have originated a new kind of linear plot for use with ESI data. It was found that in using the ESI technique that ion currents representing non-covalent complexes of cytochrome c and crown ethers could be observed in the mass spectra. The measurements of the total ion counts of peaks in the mass spectra allowed binding constants to be calculated. This had not been reported before in the literature.The accurate weight determination and the characteristic charge distribution in the ESI mass spectrum provides data suitable for computer modeling. The nature of the protein's positive charges in ESI had not been well defined. The experimentally determined binding constants allowed comparison to results from computational chemistry and molecular modeling. This result shows that the binding occurs at specific, protonated amino acid residues. The calculations performed yielding the Heats of Formation (OH f) for protonated amino acids complexed with crown ethers indicates that the OH binding of crowns increases from histidine, to arginine, to lysine. The use of a 3D model of cytochrome c from crystallographic data provided in the Brookhaven Protein Database and the SYBYL molecular modeling program allows a structural correlation to be made between the 3D model of the protein and protein/crown ether complex. The stoichiometric ratios of bound crown ether to protein determined from experiment, along with the computational results, have been used to rationalize a protein molecular model that allows predictions to be made about the potential for binding of other small molecules.
Department of Chemistry
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Thiery, Gwendoline. « Imagerie par désorption laser/spectrométrie de masse de multiples marqueurs spécifiques : développement de la technique TAMSIM "Targeted Multiplex Mass Spectrometry Imaging" ». Paris 6, 2008. http://www.theses.fr/2008PA066253.

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La protéomique est devenue un domaine de recherche essentiel en biologie et en médecine. Afin, de répondre aux enjeux de cette discipline, il est nécessaire de pouvoir caractériser et localiser les protéines exprimées au niveau cellulaire. De nombreuses techniques d’analyses in situ des ces protéines considérées comme étant des marqueurs spécifiques d’une pathologie existent et sont utilisées en routine, notamment pour le suivi des cancers, dans de nombreux laboratoires d’anatomo pathologie. La plus répandue est l’immunohistochimie (IHC). Cette technique consiste à révéler spécifiquement in situ un complexe immun (antigène-anticorps). Dans l’optique d’accroître la capacité de détection multiple (multiplexage) d’une immunoréaction, nous avons développé une nouvelle technique d’imagerie in situ de multiples marqueurs spécifiques. Des traceurs chimiques photoclivables (Tag) sont fixés spécifiquement sur des anticorps. Les anticorps marqués sont complexés in situ aux protéines cibles présentent sur le tissu. Les Tag sont ensuite clivés de leurs anticorps respectifs par désorption laser. Apres une irradiation de la coupe par le laser à 355 nm une image est générée à partir des différents spectres de masse enregistrés pour chaque Tag utilisés. Contrairement au mode MALDI, l’utilisation de la matrice n’est pas nécessaire pour favoriser l’ionisation de ces composés chimiques. Ce qui simplifie grandement l’analyse par spectrométrie de masse. Cette technique appelée TAMSIM pour TArgeted multiplex Mass Spectrometry IMaging a pu être validée pour l’analyse de différents marqueurs spécifiques localisés au sein des tissus pancréatiques et sur des sections tissulaires de foie humain.
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Spencer, Matthew Todd. « New approaches for the chemical and physical characterization of aerosols using a single particle mass spectrometry based technique ». Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3264603.

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Thesis (Ph. D.)--University of California, San Diego, 2007.
Title from first page of PDF file (viewed August 2, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Angelico, Vincent James. « The development of a mass spectrometry-based technique that uses low energy ion-surface collisions to characterize surfaces ». Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/280148.

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Low energy (tens of eV) ion-surface collisions carried out in a tandem mass spectrometer are investigated as a tool to characterize self-assembled monolayer (SAM) films. The target films are prepared by spontaneous chemisorption of thiol-based (HS-R) compounds onto Au (111) substrates. Most of the films used as targets contain alkane or fluoro-alkane backbones, some with unique groups in the terminal position (e.g., -CD₃, -OH, -OC(O)CF₃). Pyrazine is the most frequently used probe ion, however in certain cases other small organic molecules are also used. Common interactions between the impinging ion and the target film that vary as a function of film characteristics include, but are not limited to, reactive scattering, neutralization and T → V conversion. Pyrazine ion readily reacts when colliding with hydrocarbon films at 20-eV, forming product ions that incorporate a hydrogen atom or a methyl group. Several examples of the utility of these processes to characterize film properties are presented. For hydrocarbon films, ion-surface reactions of pyrazine ion resulting in addition of a hydrogen atom or a methyl group are shown to vary with the quality, chemical composition and orientation of the target film. Experiments with isotopically labeled films show that the ion beam interacts predominantly with the end groups of the film, however interactions with underlying groups increase as the film or substrate quality decreases. The orientation difference of odd and even chain length n-alkanethiols produces a measurably different degree of hydrogen addition with the higher free energy odd chain length orientation being more reactive. The composition of mixed component films (H, D or H, F) is tracked by measuring the abundance of unique reaction products, energy transfer (translational to vibrational conversion) and charge exchange properties. When mixed films containing deuterium labeled and unlabeled n-alkanethiols are subjected to collisions of 20-eV pyrazine ion, the D-addition ion abundance increases linearly with the surface concentration of D-containing alkane chains. When mixed films containing different ratios of H and F components are the target, several processes track with the changing population of surface species. As the target films become more fluorocarbon in nature H-addition decreases, total ion current reaching the detector increases, and dissociation increases. Several properties of electron transfer from the film to the ion are examined. When the probe ion and collision energy remain consant, charge exchange is shown to be primarily governed by the work function of the film and the thickness of the adsorbed layer. Fluorocarbon films, which have a higher work function than hydrocarbon films, consistently show less charge exchange. When comparing hydrocarbon films of varying chain lengths (ranging from 15 to 18 carbons), a increase of ∼1% in total ion current measured at the detector is observed for each additional methylene in the chain.
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Tang, Jianhua. « Development of a Novel Gradient Chromatofocusing Tandem Mass Spectrometry Technique for the Determination of Cationic Compounds in Biofluids ; Identification of Caspase 3 Cleavage Sites of NHE-1 by High Performance Liquid Chromatography-Mass Spectrometry ». Cleveland State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=csu1247344073.

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Tang, Jianhua. « Development of a novel gradient chromatofocusing tandem mass spectometry technique for the determination of cationic compounds in biofluids identification of caspace 3 cleavage sites of nhe-1 by high performance liquid chromatography- mass spectrometry / ». Cleveland, Ohio : Cleveland State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=csu1247344073.

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Thesis (Ph. D.)--Cleveland State University, 2009.
Abstract. Title from PDF t.p. (viewed July 29, 2009). Includes bibliographical references (p. 105). Available online via the OhioLINK ETD Center and also available in print.
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Fedrizzi, Bruno. « Identification, quantitation and origin of sulfur compounds in grape products. An approach via hyphenated mass spectrometry techniques ». Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3426543.

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The contribute of the Analytical Chemistry in the study of complex matrices, as for instance foodstuff, is crucial. In particular the development of chromatographic methods allows to quantify important technological, microbiological and physiological markers. The ensemble of all these information furthers a deeper and higher knowledge. This Ph.D. project was designed to define the tools and evaluate the contribution of an important class of molecule on wine aroma. Grape products are really important in the cultural and dietary Italian traditions; moreover Italy is both the first producer and the first consumer around the world. Oenological products have been largely studied since the early ’70, even if the lack of biochemical and microbiological knowledge and the poor sensitivity of the analytical techniques did not allow to carry an deep study on sulfur compounds. This project, planned to bid analytical and oenological chemistry, focussed its attention on the study of sulfur compounds. Dealing with complex matrices, the first problem we had to face was the matrix effects. The overcoming of such issue or the attempts in reducing it, costs to chemical laboratory, wasting of time and money to prepare suitable internal standards. In this thesis we proposed a statistical approach based on the variance component model able to handle matrix effects. The benefits obtained by this approach definitely outweigh both the slightly worse sensitivity and uncertainty. Another topic discussed in the thesis is the definition of analytical methods to quantify sulfur compounds. This subject has been studied distinguishing sulfur compounds into two sub-groups: o fermentative sulfur compounds: molecules produced by yeast metabolisms from amino acidic precursors. o varietal sulfur compounds: molecules present in specific variety, as conjugated with cysteine and glutathione. The free forms, which are sensorially active, are released during fermentation by means of a specific enzymatic activity. This further classification was kept in the development of the analytical methods because the two classes required different sensitivity as well as metabolomics study were separated. Concerning fermentative sulfur compounds a HS-SPME/GC-MS method was optimised and validated. With this method a wide range of sulfur compounds were quantified. Such tool was applied to metabolomic studies, concerning the influence of variety, ageing, yeast strain and other technological practice on the level of 13 fermentative sulfur compounds. The results obtained from the development of the analytical method permitted to highlight the potentiality of the HS-SPME technique in sampling volatile compounds in complex matrices. This approach allows an easier and safer lab conditions, avoiding the use of organic solvents. The metabolomic studies furnished important suggestion on the influence of important oenological variables on the level of important sulfur compounds. The last topic discussed in this thesis concerns the study of varietal sulfur compounds. The lack of suitable analytical technique, sufficiently rapid and avoiding the use of mercuro-organic compounds stimulated our research in verifying the performance of headspace technique in extracting these analytes. We optimised and validated HS-SPME and purge and trap methods and finally we defined a non-parametric robust approach to compare performances from different analytical methods. Owing to the recent interest of the scientific research in trying to understand the formation and evolution of varietal sulfur compounds, we focussed our attention on their precursors. The first step was the synthesis of the putative precursors, followed by the optimisation of LC-MS/MS methods to quantify them. It was possible to identify a new precursor by LC-MS/MS experiments. Finally, by the isolation of the enzyme potentially responsible of the biosynthesis of the varietal thiols precursors, we gave a preliminary explanation of the formation of these glutathionylated precursors during grape ripening. By this project it has been possible to study and apply the newest analytical techniques available and it has been possible to define statistical procedures to overcome the most common issues in studying complex matrices. Furthermore it was clarified the contribution of an important class of molecules, such as sullfur compounds, on oenological matrices.
Il contributo della Chimica Analitica nello studio delle matrici complesse, quali ad esempio quelle alimentari, è cruciale. In particolare lo sviluppo di metodi cromatografici avanzati può permettere di dosare importanti marker tecnologici, microbiologici e fisiologici e quindi consentire un approfondimento delle attuali conoscenze. Questo lavoro è stato concepito allo scopo di definire gli strumenti per valutare il contributo di un’importante classe di molecole all’aroma dei vini. Il vino riveste un ruolo di primaria importanza nelle tradizioni culturali ed alimentari Italiane, inoltre l’Italia risulta primo produttore e primo consumatore mondiale di vino. I prodotti enologici sono stati largamente studiati fin dai primi anni ’70, anche se l’assenza di conoscenze biochimiche e microbiologiche e la mancanza di tecniche analitiche sufficientemente sensibili non ha consentito lo studio esaustivo della classe dei composti solforati. Questa tesi, nata da esigenze legate alla chimica analitica e alla chimica enologica, ha avuto come punto centrale lo studio dei composti solforati nei vini. Il primo problema che si è dovuto affrontare nello studio di matrici complesse come quelle enologiche è stato quello relativo agli effetti matrice. Il superamento o il contenimento di questo problema crea ogni giorno costi in termini di tempo e di preparazione di opportuni standard interni. In questa tesi si è proposto un metodo statistico basato sul modello a componente di varianza in grado di gestire questo problema. I vantaggi sono notevoli, a fronte di una incertezza leggermente maggiore e di una sensibilità di poco peggiorata. Altro argomento trattato è stata la definizione dei metodi analitici in grado di quantificare e quindi di studiare i composti solforati. Questa materia è stata affrontata riconoscendo una prima distinzione all’interno del gruppo degli analiti indagati: o composti solforati fermentativi: molecole derivanti dal metabolismo del lievito a partire da precursori amminoacidici o composti solforati varietali: molecole presenti in specifiche varietà come coniugati della cisteina e del glutatione e rilasciati durante la fermentazione alcolica ad opera di specifiche attività enzimatiche. Questa suddivisione è stata mantenuta anche nello sviluppo dei metodi analitici, in quanto sensibilità richieste e conseguenze metabolomiche erano anch’esse distinte. Per quanto riguarda i composti solforati fermentativi, durante il dottorato di ricerca è stato ottimizzato e validato un metodo HS-SPME/GC-MS per l’analisi di un’ampia gamma di molecole tipicamente derivanti dal metabolismo del lievito. Tale approccio è poi stato la base per studi di natura più squisitamente metabolomica in cui è stato verificato come il cultivar (i.e. la varietà), l’invecchiamento, il ceppo di lievito e altre pratiche tecnologiche potessero influenze il livello e l’evoluzione degli analiti indagati. I risultati ottenuti per quanto attiene lo sviluppo del metodo in spettrometria di massa hanno potuto confermare con la tecnica SPME con campionamento in spazio di testa sia una tecnica di elezione per l’analisi di molecole volatili. Inoltre questo approccio consente una gestione semplice ed enviromental friendly in confronto con i più obsoleti metodi di estrazione con solvente. Gli studi metabolomici hanno consentito di trarre importanti considerazioni su aspetti molto importanti nella definizione della qualità del prodotto finale. Tali risultati consentono anche una trasferibilità nei settori della ricerca applicata e dell’enologia. Come ultima classe di analiti indagati si sono studiati i composti solforati varietali. L’assenza di metodi sensibili e sufficientemente rapidi da essere applicati per studi su un numero significativo di campioni ha spinto la nostra attenzione alla verifica delle potenzialità delle tecniche in spazio di testa nel dosare queste molecole. Si sono ottimizzati e validati metodi HS-SPME e purge and trap ed è stata definita una procedura non parametrica robusta per il confronto delle performance delle diverse procedure. Visto il recente interesse della ricerca scientifica operante nel settore al controllo della formazione ed evoluzione di queste molecole, abbiamo focalizzato la nostra attenzione sui precursori dei composti solforati varietali. Il primo stadio è stata la sintesi di queste molecole, seguito poi dall’ottimizzazione di metodi LC-MS/MS per il dosaggio di queste molecole. In questo contesto è stato possibile identificare per la prima volta un nuovo potenziale precursore di aroma, tramite esperimenti LC-MS/MS. Da ultimo, attraverso l’isolamento dell’enzima responsabile della biosintesi dei precursori d’aroma è stato possibile proporre una preliminare spiegazione alla formazione di tali molecole durante la maturazione della materia prima. In conclusione, grazie a questa tesi di dottorato, è stato possibile approfondire ed applicare alcune delle più moderne tecniche analitiche a disposizione, è stato possibile definire procedure statistiche per superare i più comuni ostacoli nello studio di matrici complesse, ed è stato possibile chiarire il contributo di una classe importante di molecole come i composti solforati nelle matrici enologiche.
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Shewmaker, Patricia Lynn Wallace. « Enhanced biodegradation of phenolic compounds and cellular fatty acid analysis of bacteria using infrared pyrolysis/gas chromatography-mass spectrometry ». Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/25732.

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Livres sur le sujet "Mass Spectrometry technique"

1

Jehuda, Yinon, dir. Forensic mass spectrometry. Boca Raton, Fla : CRC Press, 1987.

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1919-, Karasek Francis W., Hutzinger O et Safe S, dir. Mass spectrometry in environmental sciences. New York : Plenum Press, 1985.

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Jehuda, Yinon, dir. Forensic applications of mass spectrometry. Boca Raton, Fla : CRC Press, 1995.

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J, Gaskell S., dir. Mass spectrometry in biomedical research. Chichester : Wiley, 1986.

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1960-, Sechi Salvatore, dir. Quantitative proteomics by mass spectrometry. Totowa, N.J : Humana Press, 2007.

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Alvin, Fox, et International Symposium on the Interface between Microbiology and Analytical Chemistry (1st : 1987 : University of South Carolina), dir. Analytical microbiology methods : Chromatography and mass spectrometry. New York : Plenum Press, 1990.

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Elmar, Heinzle, Reuss Matthias, Institut für Umweltforschung, International Federation of Automatic Control. et International Federation of Automatic Control. Technical Committee on Applications., dir. Mass spectrometry in biotechnological process analysis and control. New York : Plenum Press, 1987.

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Lantbruksuniversitet, Sveriges, dir. Direct current plasma(DCP)-atomic emission spectrometry : Development of technique and applications to biological materials. Uppsala : Sveriges Lantbruksuniversitet, 1996.

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Butler, John M. Improved analysis of DNA short tandem repeats with time-of-flight mass spectrometry. Washington, D.C : U.S. Dept. of Justice, Office of Justice Programs, National Institute of Justice, 2001.

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Busch, Kenneth L. Mass spectrometry/mass spectrometry : Techniques and applications of Tandem mass spectrometry. New York, N.Y : VCH Publishers, 1988.

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Chapitres de livres sur le sujet "Mass Spectrometry technique"

1

Malainey, Mary E. « Mass Spectrometry ». Dans Manuals in Archaeological Method, Theory and Technique, 411–25. New York, NY : Springer New York, 2010. http://dx.doi.org/10.1007/978-1-4419-5704-7_31.

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Colton, Richard J., David A. Kidwell, George O. Ramseyer et Mark M. Ross. « Secondary Ion Mass Spectrometry : A Multidimensional Technique ». Dans ACS Symposium Series, 160–93. Washington, D.C. : American Chemical Society, 1985. http://dx.doi.org/10.1021/bk-1985-0291.ch010.

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Karlsson, Roger, Darren Chooneea, Elisabet Carlsohn, Vesela Encheva et Haroun N. Shah. « Characterization of Bacterial Membrane Proteins Using a Novel Combination of a Lipid Based Protein Immobilization Technique with Mass Spectrometry ». Dans Mass Spectrometry for Microbial Proteomics, 157–74. Chichester, UK : John Wiley & Sons, Ltd, 2010. http://dx.doi.org/10.1002/9780470665497.ch8.

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Calvano, Cosima D., Antonio Monopoli et Carlo G. Zambonin. « MALDI Mass Spectrometry : A Promising Non-Chromatographic Technique ». Dans Food Authentication, 393–411. Chichester, UK : John Wiley & Sons, Ltd, 2017. http://dx.doi.org/10.1002/9781118810224.ch12.

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Snyder, A. Peter. « Electrospray : A Popular Ionization Technique for Mass Spectrometry ». Dans ACS Symposium Series, 1–20. Washington, DC : American Chemical Society, 1996. http://dx.doi.org/10.1021/bk-1995-0619.ch001.

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Czanta, M., C. Strietzel, H. J. Besch, H. F. Beyer, F. Bosch, R. Deslattes, F. Förster et al. « Spectroscopy of Ly-α Lines at Storage Rings by Crystal Spectrometry and Absorption Edge Technique ». Dans Atomic Physics at Accelerators : Mass Spectrometry, 491–94. Dordrecht : Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-015-1270-1_55.

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Joshi, Vivek, et Elena Chernokalskaya. « Filtration as a Sample Preparation Technique Prior to Mass Spectrometry : Selecting the Right Filtration Device ». Dans Sample Preparation in Biological Mass Spectrometry, 61–75. Dordrecht : Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-0828-0_4.

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Jespersen, S., W. M. A. Niessen, U. R. Tjaden, J. van der Greef, E. Litborn, U. Lindberg et J. Roeraade. « Picoliter Vials : A New Sample Handling Technique for Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry ». Dans Mass Spectrometry in the Biological Sciences, 217–26. Totowa, NJ : Humana Press, 1996. http://dx.doi.org/10.1007/978-1-4612-0229-5_11.

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Varma, Karthik, Sreeraj Gopi et Józef T. Haponiuk. « HRMS : The Cutting-Edge Technique in Clinical Laboratory ». Dans High-Resolution Mass Spectrometry and Its Diverse Applications, 45–60. New York : Apple Academic Press, 2022. http://dx.doi.org/10.1201/9781003304258-3.

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Colton, R. J. « Organic Secondary Ion Mass Spectrometry : Theory, Technique, and Application ». Dans Springer Series in Chemical Physics, 456–61. Berlin, Heidelberg : Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-82724-2_122.

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Actes de conférences sur le sujet "Mass Spectrometry technique"

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Fredeen, Kenneth J. « Applications of Laser Sampling Inductively Coupled Plasma Mass Spectrometry ». Dans Laser Applications to Chemical Analysis. Washington, D.C. : Optica Publishing Group, 1992. http://dx.doi.org/10.1364/laca.1992.pd2.

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Laser sampling inductively coupled plasma mass spectrometry (LS-ICP-MS) is a increasingly popular technique for the direct determination of trace elements in solid materials. In this technique, a high-power pulsed laser is used to vaporize a portion of a solid specimen. The sample vapor is then swept into an ICP discharge, which ionizes the vapor before it is subsequently sampled by a mass spectrometer.
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Goeringer, D. E., et W. H. Christie. « Resonance Ionization Mass Spectrometry Using Ion-Beam Sampling ». Dans Lasers in Material Diagnostics. Washington, D.C. : Optica Publishing Group, 1987. http://dx.doi.org/10.1364/lmd.1987.thc2.

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Sputter atomization/resonance ionization mass spectrometry (SA/RIMS) is a highly sensitive technique for materials analysis which combines ion beam sputtering, resonance ionization, and mass spectrometry. A pulsed beam of high-energy primary ions bombards the sample producing a plume of neutral atoms. The cloud of sputtered neutrals is intersected and ionized by a synchronized, pulsed laser beam tuned to a resonant transition for specific sample atoms. Laser-generated ions are then extracted into a mass spectrometer for mass analysis. Ion beam sputtering allows the sampling process to be highly controlled by varying the energy, current density, and composition of the primary beam; the pulsed nature of the beam results in efficient sample utilization. Use of a micro-focused beam permits imaging of small areas and particles. The pulsed dye laser generates the high optical power necessary to efficiently ionize the sputtered atoms. Mass analysis of the laser-generated ions provides the capability for isotope ratio measurements.
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Bushaw, B. A., F. Juston, W. Nörtershäuser, N. Trautmann, P. Voss-de-Haan et K. Wendt. « Ultratrace Analysis of Calcium with High Isotopic Selectivity by Resonance Ionization Mass Spectrometry ». Dans Laser Applications to Chemical and Environmental Analysis. Washington, D.C. : Optica Publishing Group, 1996. http://dx.doi.org/10.1364/lacea.1996.lfb.7.

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Using resonance ionization mass spectrometric techniques (RIMS) for ultratrace analysis has a number of advantages over conventional techniques: 1. Extremely high sensitivity in the fg to ag range per sample is possible with the high cross sections for optical excitation. 2. Ultrahigh elemental and isotopic selectivity is achieved by the uniqueness of the optical resonance lines of individual elements and isotopes. 3. Background is strongly suppressed by subsequent mass spectrometry. Unfortunately, the application of the technique is complicated by the complexity of the experimental set-up, particularly the laser system, and hence is limited to a small number of research institutes so far.
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Evans, Charles A. « Laser Microprobe Mass Spectrometry and Its Relationship to Other Microanalytical Techniques ». Dans Lasers in Material Diagnostics. Washington, D.C. : Optica Publishing Group, 1987. http://dx.doi.org/10.1364/lmd.1987.thc1.

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There are a variety of techniques employed for the microanalysis of materials. The majority of these techniques employ focused ions or electron beams to probe the materials. In recent years, a technique called Laser Microprobe Mass Spectrometry has been developed to provide a unique and complementary characterization capability. This paper will deal with the basic phenomena involved, instrumentation and illustrations of the technique's utility with a variety of applications.
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Wendt, K., K. Blaum, B. A. Bushaw, C. Geppert, P. Müller, W. Nörtershäuser, A. Schmitt, N. Trautmann et B. Wiche. « A Diode-Laser Based Resonance Ionization Mass Spectrometer for Selective Ultratrace Analysis ». Dans Laser Applications to Chemical and Environmental Analysis. Washington, D.C. : Optica Publishing Group, 1998. http://dx.doi.org/10.1364/lacea.1998.ltuc.4.

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Resonance ionization mass spectrometry (RIMS) has become a widely used technique for isotope-selective ultra-trace analysis1-4. It provides complete isobaric suppression, high overall efficiency and strongly increased isotopic selectivity in respect to conventional mass spectrometers. Still a major drawback for the application of this technique is the complexity of the experimental set-up, particularly the laser system, which restricts utilization of the technique to a small number of university and research institutes so far.
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Miller, C. M., R. Engleman et R. A. Keller. « Resonance ionization mass spectrometry for high-resolution mass-resolved spectra of rare isotopes ». Dans OSA Annual Meeting. Washington, D.C. : Optica Publishing Group, 1985. http://dx.doi.org/10.1364/oam.1985.tha2.

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Previous isotope ratio measurements using resonance ionization mass spectrometry (RIMS) have used element selective photoionization with isotope ratios measured by dispersion of ions in a mass spectrometer. To increase the accuracy and dynamic range of isotope ratio measurements, it may be necessary to use isotopically selective ionization. To be successful in this task it is necessary to know isotope shifts and hyperfine structures of the optical transition(s) used for the isotopes of interest. We are particularly interested in rare and sometimes highly radioactive elements for which this information is not readily available. We demonstrate that the sensitivity and mass selectivity of the RIMS technique itself can be used to obtain the needed spectra. With this goal in mind, RIMS was used to acquire high-resolution optical spectra of rare isotopes. To demonstrate the potential of this technique, hyperfine spectra of the 2 D 3 / 2 0 ← 2 D 3 / 2 lutetium transition at 22,125 cm–1 are presented for 176Lu, 175Lu, 174Lu, and 173Lu. The latter two are rare isotopes with half-lives of 3.3 and 1.4 yr whose optical spectroscopy has not previously been explored. Sensitivity is documented by the fact that the total amount of these rare isotopes in our sample was 2 × 10–10 g and 3 × 10–11 g. Analysis of the spectra confirms that the spin of 174Lu is unity and yields values for the hyperfine constants and isotope shifts of these nuclei.
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Manfredi, Marcello, Simona Martinotti, Mauro Patrone, Maria Paola Sassi, Elia Ranzato et Emilio Marengo. « Targeted quantitation of HMGB1 protein by label-free Mass Spectrometry technique ». Dans 2015 IEEE International Symposium on Medical Measurements and Applications (MeMeA). IEEE, 2015. http://dx.doi.org/10.1109/memea.2015.7145260.

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Lubman, David M., Roger Tembreull, Chung Hang Sin et Homing Pang. « Laser-induced ionization spectroscopy of small biological precursors in supersonic beam-mass spectrometry ». Dans International Laser Science Conference. Washington, D.C. : Optica Publishing Group, 1986. http://dx.doi.org/10.1364/ils.1986.tue3.

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In our work resonant two-photon ionization (R2PI) in supersonic jets is used as a means of optically selecting ions for mass spectrometry. The use of supersonic beam injection provides internally ultracold molecules with sharp spectral features for chemical analysis for molecules whose spectra would otherwise exhibit broad, unresolvable spectral contours at room temperature. The use of high-powered tunable monochromatic laser sources can be used to probe this sharp structure by using laser R2PI spectroscopy. This method has been used for analysis of small biological species based on the combination of wavelength selectivity and the high efficiency for producing molecular ions by the R2PI technique. One method investigated for use in solubilizing nonvolatile and thermally labile molecules involves expansions of supercritical fluids of CO2 and N2O at up to 400-atm backpressure in to a mass spectrometer at 10-5 Torr. The expansion of this ultradense jet is shown to provide cold spectra for molecules which would normally require significant heating for volatilization into the gas phase. A second method used in our work for volitilization of nonvolatiles uses laser desorption to rapidly heat molecules off a surface before they can decompose. The resulting desorbed cloud is then swept into a supersonic jet and into a TOFMS for analysis by R2PI. The parameters required to volatilize various compounds and the spectroscopic and mass spectrometric results for several small biological systems including amino acids, drugs, catecholamines, and vitamins are discussed.
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Benson, Brian L., Stuart A. Oerle et Melvin V. Kilgore. « Liquid Chromatography/Mass Spectrometry A New Technique for Water Recovery System Testing ». Dans International Conference On Environmental Systems. 400 Commonwealth Drive, Warrendale, PA, United States : SAE International, 1990. http://dx.doi.org/10.4271/901255.

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Murray, Kermit K., Michelle D. Beeson et David H. Russell. « Laser Ionization of Biomolecules in Solution ». Dans Laser Applications to Chemical Analysis. Washington, D.C. : Optica Publishing Group, 1994. http://dx.doi.org/10.1364/laca.1994.tha.5.

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Many powerful laser based methods are unavailable for the analysis of molecules in solution. Techniques for the analysis of liquids are particularly important for the study of biomolecules, whose natural environment is a water solution. Mass spectrometry is a powerful analytical technique, but liquids and mass spectrometers are fundamentally incompatible. We have developed a technique for laser ionization of biomolecules in solution by applying matrix-assisted laser desorption ionization (MALDI) to liquid aerosols. In the typical MALDI experiment, the analyte biomolecule is deposited from solution onto a metal surface with a 100 to 50,000 molar excess of a suitable matrix, usually a UV absorbing organic acid.1 The solvents are allowed to evaporate and the sample is inserted into the source region of a mass spectrometer. Light from a pulsed laser is absorbed by the matrix causing both ablation of the surface and ionization of the intact biomolecule. In the aerosol MALDI experiment, 2,3 the analyte biomolecule is dissolved in a methanol solution with an ultraviolet absorbing matrix. The aerosol is sprayed into vacuum, desolvated, and ionized by pulsed UV laser radiation. The ions are mass separated in a time-of-flight (TOF) mass spectrometer. Aerosol MALDI mass spectra have been obtained for a variety of peptides and proteins with molecular weights as large as 80,000. We have used aerosol MALDI as a liquid chromatography detection method4 (LC/MS) and as a probe of aerosol and cluster chemistry.5 This paper gives a general description of aerosol MALDI and discusses some recent results for peptide and protein ionization.
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Rapports d'organisations sur le sujet "Mass Spectrometry technique"

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Fairbank, W. M. Jr. [Photon burst mass spectrometry technique.] Final report. Office of Scientific and Technical Information (OSTI), avril 1996. http://dx.doi.org/10.2172/212673.

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Jenkins, Amanda L., Eric J. Bruni, Leonard C. Buettner, Ai Sohrabi et Michael W. Ellzy. Vapor Pressure Determination of VM Using the Denunder-Liquid Chromatography-Mass Spectrometry Technique. Fort Belvoir, VA : Defense Technical Information Center, janvier 2015. http://dx.doi.org/10.21236/ada613614.

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MORALES-ARTEAGA, MARIA, et REBECCA THOMAS. NWAL VALIDATION REPORT FOR U ASSAY BY POTENTIOMETRIC TITRATION (MODIFIED DAVIES AND GRAY TECHNIQUE) AND U AND PU ASSAY BY ISOTOPE DILUTION MASS SPECTROMETRY. Office of Scientific and Technical Information (OSTI), mars 2022. http://dx.doi.org/10.2172/1860321.

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BALSLEY, STEVEN D., JAMES F. BROWNING et CAROL A. LADUCA. Mass Spectrometric Calibration of Controlled Fluoroform Leak Rate Devices : Technique and Uncertainty Analysis. Office of Scientific and Technical Information (OSTI), avril 2003. http://dx.doi.org/10.2172/810000.

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Moores, Lee C., P. U. Ashvin, I. Fernando et Garret W. George. Synthesis of 2-Methoxypropyl Benzene for Epitope Imprinting. U.S. Army Engineer Research and Development Center, juillet 2022. http://dx.doi.org/10.21079/11681/44883.

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Harmful algal blooms (HABs) are occurring with increasing frequency and severity across the globe in part due to climate change and anthropogenic pollution (Bullerjahn et al. 2016). HABs produce several classes of toxins; however, microcystins (MCs) are the most commonly studied (Lone et al. 2015) and can be potent toxins with LD50s in the range of 50 μg/kg (Puddick et al. 2014). Sample analysis in laboratories, typically by high-pressure liquid chromatography tandem mass spectrometry (HPLC-MS/MS) or by Enzyme Linked Immunosorbent Assays (ELISAs) (USEPA 2015). These analytical techniques are highly sensitive and selective for the given toxins; however, the time it takes to collect, transfer, prepare, and analyze a sample before the data can be reported is significant; often, multiple days is the most expeditious.
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Hamilton, T. H., et J. McAninch. Measurement of plutonium and other actinide elements at the center for accelerator mass spectrometry : a comparative assessments of competing techniques. Office of Scientific and Technical Information (OSTI), février 1999. http://dx.doi.org/10.2172/7993.

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Benn, D., R. Linnen et T. Martins. Evaluating white mica as an indicator mineral for lithium bearing pegmatites, Wekusko Lake pegmatite field, Manitoba, Canada. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/328982.

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This project investigates the potential use of white micas as an indicator mineral within Li-bearing pegmatites and the potential of field portable techniques, such as Raman spectroscopy and Laser Induced Breakdown Spectroscopy (LIBS) as real-time techniques in exploration. The pegmatites in the Wekusko Lake field, Manitoba, Canada, display five zones of varying mineralization. White micas display two textures in the field (primary igneous and secondary) and four textures were identified by backscattered electron imaging (poor zonation, rimmed, patchy and exsolution). The white micas were analysed by Electron Probe Micro-Analysis (EPMA) and Laser Ablation Induction-Coupled Plasma Mass Spectroscopy (LA-ICP-MS) and the results show a strong correlation in the Li content of the white mica and the whole rock Li2O obtained from the assays of drill core. The K/Rb vs. Cs contents of the white mica indicate that the most prospective dikes contain moderate to highly evolved grains. The use of portable Raman Spectrometer, while useful for mineral identification, was not able to detect a significant Li signature at the concentrations tested (1500-6000 ppm).
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Evans, Jr, et Charles A. Development and Application of SIMS (Secondary Ion Mass Spectrometry) Characterization Techniques for the Study of Impurities and Impurity Motion in (HgCd)Te and CdTe. Fort Belvoir, VA : Defense Technical Information Center, septembre 1985. http://dx.doi.org/10.21236/ada163047.

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Park, C. J., et G. E. M. Hall. Electrothermal Vapourization As a Means of Sample Introduction Into An Inductively Coupled Plasma Mass Spectrometer : a Preliminary Report of a New Analytical Technique. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1986. http://dx.doi.org/10.4095/120691.

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Naim, Michael, Gary R. Takeoka, Haim D. Rabinowitch et Ron G. Buttery. Identification of Impact Aroma Compounds in Tomato : Implications to New Hybrids with Improved Acceptance through Sensory, Chemical, Breeding and Agrotechnical Techniques. United States Department of Agriculture, octobre 2002. http://dx.doi.org/10.32747/2002.7585204.bard.

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The tomato, a profitable vegetable crop in both the USA and Israel, has benefited significantly from intensive breeding efforts in both countries, and elsewhere (esp. Holland). : Modem hybrids are highly prolific and resistant to a variety of major pests. They produce attractive, firm fruit for both processing and fresh-marketing. In all cases, however, reduction in flavor and aroma have occurred concomitantly with the increase in yield. Sugars-acids ratio dominate fruit taste, whereas aroma volatiles (potent at minute ppb and ppt levels) contribute to the total characteristic tomato flavor. An increase in sugars (1-2%) contributes significantly to tomato fruit taste. However, because of energy reasons, an increase in fruit sugars is immediately compensated for by a decrease in yield. Our main objectives were to: (a) pinpoint and identify the major impact aroma components of fresh tomato; (b) study the genetic and environmental effects on fruit aroma; (c) determine precursors of appealing (flavors) and repelling (off-flavors) aroma compounds in tomato. Addition of saturated salts blocked all enzymatic activities prior to isolation of volatiles by dynamic and static headspace, using solvent assisted flavor evaporation (SAFE) and solid phase micro-extraction (SPME) from highly favored (FA-612 and FA-624) and less preferred (R 144 and R 175) tomato genotypes. Impact aroma components were determined by gas chromatography-olfactometry (GC-O), gas chromatography-mass spectrometry (GC- MS) and aroma extract dilution analysis (AEDA). The potent odorant (Z)-1,5-octadien-3-one, was identified for the first time in fresh tomato. From the ca. 400 volatile compounds in the headspace of fresh tomato, the following compounds are proposed to be impact aroma compounds: (Z)-3-hexenal, hexanal, 1-penten-3-one, 2-phenylethanol, (E)-2-hexenal, phenyl acetaldehyde, b-ionone, b-damascenone, 4-hydroxy-2,5-dimethyl-3-(2H)-furanone (FuraneolR), (Z)-l,5-octadien-3-one, methional, 1-octen-3-one, guaiacol, (E,E)- and (E,Z)- 2,4-decadienal and trans- and cis-4,5-EPOXY -(E)-2-decenal. This confirms the initial hypothesis that only a small number of volatiles actually contribute to the sensation of fruit aroma. Tomato matrix significantly affected the volatility of certain impact aroma components and thus led to the conclusion that direct analysis of molecules in the headspace . may best represent access of tomato volatiles to the olfactory receptors. Significant differences in certain odorants were found between preferred and less-preferred cultivars. Higher consumer preference was correlated with higher concentrations of the following odorants: l-penten-3-one, (Z)-3-hexenal, (E,E)- and (E,Z)-2,4-decadienal and especially Furaneol, whereas lower consumer preference was associated with higher concentrations of methional, 3-methylbutyric acid, phenylacetaldehyde, 2-phenylethanol, and 2-isobutylthiazole. Among environmental factors (salinity, N source, growth temperature), temperature had significant effects on the content of selected aroma compounds (e.g., 3-methylbutanal, 1- penten-3-one, hexanal, (Z)-3-hexenal, (E)-2-hexenal, 2-isobutylthiazole, 6-methyl-5-hepten- 2-one, 1-octen-3-one, methional, 2-phenylethanal, phenyl acetaldehyde, and eugenol) in fresh tomatoes. Salt stress (20 mM NaCl) increased the content of odorants such as (Z)-3-hexenal, 2-phenylethanol and 3-methylbutanal in the R-144 cultivar whereas salinity had minor effects on 1-pentene-3-one, 2-isobutylthiazole and b-ionone. This fundamental knowledge obtained by comprehensive investigation, using modem chemical, sensory and agrotechnical methodology will assist future attempts to genetically modify the concentrations of key odorants in fresh tomatoes, and thus keep the tomato production of Israel and the USA competitive on the world market.
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