Dissertations / Theses: 'Laser desorption ionization MS'

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Tummala, Manorama. "Surfactant-Aided Matrix Assisted Laser Desorption/Ionization Mass Spectrometry (SA-MALDI MS)." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1100672049.

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Sorensen, Christina M. "ESI-MS and MALDI-TOF-MS for the characterization and analysis of metallo-oligomers and proteins." Laramie, Wyo. : University of Wyoming, 2005. http://proquest.umi.com/pqdweb?did=1031044031&sid=4&Fmt=2&clientId=18949&RQT=309&VName=PQD.

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Segu, Mohideen Mohamed Zaneer. "TARGET MODIFICATION FOR ENHANCED PERFORMANCE MATRIX ASSISTED LASER DESORPTION IONIZATION (MALDI) MASS SPECTROMETRY." Available to subscribers only, 2008. http://proquest.umi.com/pqdweb?did=1674093101&sid=1&Fmt=2&clientId=1509&RQT=309&VName=PQD.

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Thesis (Ph. D.)--Southern Illinois University Carbondale, 2008.
"Department of Chemistry." Keywords: Enhanced MALDI, MALDI-MS, On-probe separation, Protein-surface interactions, Sublayers, Surface binding capacity. Includes bibliographical references (p. 130-148). Also available online.

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Ratcliffe, Lucy Vivien. "Proteomic strategies for protein and biomarker identification by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS)." Thesis, Nottingham Trent University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431885.

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This thesis describes the development of novel strategies for the analysis of peptides by MALDI mass spectrometry. The developed techniques are applied to the identification of protein and proteomic biomarkers for melanoma. A commercial atmospheric pressure (APMALDI) source (MassTechnologies, Burtonsville, MD, USA) was modified to allow operation with a high powered nitrogen laser and independent PC control of the sample stage. A software interface was developed using LabVIEW 6.1 that allows full control of the target position with respect to the laser fibre optic interface, allowing the target to be adjusted within any point within a particular sample spot to enhance signal quality. The modified AP-MALDI-QIT interface was evaluated for the analysis of standard peptide mixtures and tryptic digests of proteins. AP-MALDI-QIT analysis of tryptic peptides following capillary liquid chromatographic (LC) separation and direct analysis of a protein digest is reported. Peptide fragments were identified by peptide mass fingerprinting from mass spectrometric data and sequence analysis obtained by tandem mass spectrometry of the principal mass spectral peaks using a data-dependent scanning protocol. These data were compared with those from mass spectrometric analysis using capillary LC/MALDI-time-of-flight (TOF) and capillary LC/electrospray ionisation (ESI)-quadrupole TOF. For all three configurations the resulting data were searched against the MSDB database, using MASCOT and the sequence coverage compared for each technique. Complementary data were obtained using the three techniques. A bottom-up proteomic methodology for the peptide profiling of human serum samples using MALDI mass spectrometry was developed. Reproducibility studies were carried out to define the MALDI measurement precision. Pre-analytical sample handling factors, such as room temperature incubation and freeze thaw cycles have also been investigated. The methodology developed was applied to the analysis of serum peptides from stage IV melanoma patients and healthy control subjects. Prediction of human melanoma metastatic cancer from peptide profiling using artificial neural networks (ANNs) model classified 98 % of samples correctly. The identification of three out of six ions predicted by the ANNs model to be indicative biomarkers that have good predictive performance were identified using MALDI PSD, AP-MALDI MSIMS and LC-ESI-MS/MS. Two of the ions were shown to belong to the same identified peptide, u-l-acid glycoprotein precursor (l, 2) which correctly predicted 95 % (i.e. 45/50) of metastatic melanoma patients.

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PENG, LIJUAN. "MATRIX-ASSISTED LASER DESORPTION/IONIZATION (MALDI) TARGET MODIFICATION FOR ENHANCED PROTEOMICS ANALYSIS AND PLASMA POLYMER CHARACTERIZATION BY MALDI MASS SPECTROMETRY." OpenSIUC, 2010. https://opensiuc.lib.siu.edu/dissertations/207.

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The work described in this dissertation is divided into three sections. In the first section three surface modifications are used to produce MALDI targets having reduced surface-protein binding affinity with a goal of increasing peptide/protein MALDI ion signals and lowering the limits of detection (LODs) for proteins and peptides. The second section discusses a bioselective MALDI target, produced via radio frequency (rf) plasma deposited ethylenediamine (EDA), for on-target separation of complex protein mixtures. The third section develops a new approach for characterization of rf plasma-deposited bulk polymers by using MALDI MS. Previous studies in our group have shown that the analyte signal in a MALDI MS experiment is strongly influenced by the binding interactions between the target surface and the analyte. Specifically, the analyte signal increases with decreasing surface-analyte binding affinity, which has been attributed to more unbound analyte being available for incorporation within the MALDI matrix. In the presented studies MALDI targets are modified with polyethylene glycol (PEG)-like structures via chemical grafting of PEG onto polyurethane (PU) film and rf plasma polymerization of ethylene oxide vinyl ether (EO2) and tetraglyme. It is shown that there are enhancements in the protein MALDI ion signals on these modified targets and that the LOD for target proteins is decreased by a factor of 2-10 in comparison with the conventional stainless steel MALDI target. On-probe affinity capture (OPAC) MALDI MS, developed in our group, has shown that functional group modified MALDI targets can be used to rapidly and selectively isolate target analytes from complex samples. For applications involving analysis of complex peptide/protein mixtures, fractionation of the mixture on the basis of component pI can reduce MALDI ion suppression effects leading to efficient ionization of larger numbers of mixture components. In the present studies a MALDI target is modified by rf plasma deposition of polymerized EDA to yield an OPAC target suitable for capture of proteins with low pI (expected to be negatively charged at neutral pH). In subsequent MALDI MS analyses of both control and biological mixtures after fractionation on the OPAC target it is observed that a significant number of additional peptide/protein ion signals are detected. The results of these studies, along with studies of the effects of the density of the primary amine functionality on the bio-selective MALDI ion signals, are presented. The complex nature of the polymer films resulting from plasma polymerization makes it very difficult to characterize their molecular structures. The presented study is the first to use MALDI MS for characterization of rf plasma-deposited bulk polymers and for investigation of the rf plasma polymerization process. It is shown that the mass spectra of the soluble fraction of allyl alcohol, EO2 and ethylene glycol butyl vinyl ether -plasma polymers contain clear polymer series. Furthermore, it is found that the peaks of the EO2-plasma polymer series shift to higher molecular weight distribution with decreasing plasma duty cycle. In contrast to predictions based on conventional radical polymerization, the mass spectra of all three plasma polymers exhibit the same repeat unit of 44 Da, for which the most likely structure would be -(CH2CH2O)-.

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Yao, Mengmeng. "Determining Polymer Blend Surface Concentration Using Surface Layer Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (SL-MALDI-TOF MS)." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1407941345.

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Hill, Jacob A. Hill. "SURFACE LAYER MATRIX-ASSISTED LASER DESORPTION IONIZATION TIME OF FLIGHT MASS SPECTROMETRY (SL-MALDI-TOF MS) ANALYSIS OF POLYMER BLEND SURFACE COMPOSITION." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1514479406062149.

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Thenstedt, Niklas. "Detektion av hydrolyserad β-laktamantibiotika i plasma med Matrix-Assisted Laser Desorption Ionization – Time of Flight Mass Spectrometry och Liquid Chromatography tandem Mass Spectrometry." Thesis, Örebro universitet, Institutionen för hälsovetenskaper, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-84594.

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Introduktion Antibiotikaresistens är ett globalt växande problem. Till gruppen β-laktamantibiotika hör piperacillin-tazobaktam och cefotaxim som båda verkar genom att försvaga cellväggen med kovalenta bindningar till peptidoglykanlagret som lyserar cellen. E. coli och K. pneumoniae tillhör gruppen Enterobacteriaceae, som är en del av den humana tarmfloran och ofta förekommande vid urinvägsinfektion och sepsis. Utvidgat Spektrum β-Laktamas (ESBL) är ett enzym som finns hos Enterobacteriaceae och som hydrolyserar β-laktamantibiotika. Matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) är en kvalitativ analysteknik för detektion av kemiska föreningar i avseende på massa och laddning. Kännedom om antibiotikametaboliters molekylvikt vid hydrolys möjliggör detektion. Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS) är en högsensitiv kvantifieringsmetod som separerar molekyler i avseende på polaritet för vidare detektion i avseende på massa och laddning. Syfte Syftet med denna studie var att vidareutveckla en snabb och effektiv metod för att påvisa nedbrytning av piperacillin-tazobaktam och cefotaxim i blodplasma med LC-MS/MS. Material och Metod Tiofaldigt sjunkande koncentrationer av piperacillin-tazobaktam från 2000 till 2 µg/ml, och cefotaxim med koncentrationerna 500 till 0,5 µg/ml analyserades med MALDI-TOF MS, dels intakt men även med bakterierna E. coli och K. pneumoniae med uttryck av olika resistensmekanismer. Vid optimerade koncentrationer spikades plasmaprover med nedbrutet antibiotika som sedan kvantifierades med LC-MS/MS. Resultat Lägsta detektionsgräns med MALDI-TOF MS för intakt och hydrolyserat piperacillin-tazobaktam var 20/2,5 µg/ml. För cefotaxim var lägsta gränsen 5 µg/ml. Med kliniskt relevanta blodkoncentrationer gick hydrolys inte att detektera för. Med tre bakteriekolonier/50 µl kunde dock hydrolys detekteras och kvantifieras med LC-MS/MS. Slutsats Detektion av β-laktamantibiotika är möjligt med både MALDI-TOF MS och LC-MS/MS. För att påvisa hydrolys krävdes större mängder bakterier än förväntat med LC-MS/MS.
Introduction Antibiotic resistance is a global growing problem. Piperacillin-tazobactam and cefotaxime are parts of the group β-lactam antibiotics. The common feature is to inhibit the cell wall synthesis by covalent bindings to the peptidoglycan layer and thereby causing lysis of the bacterial cell. E. coli and K. pneumoniae are members of the Enterobacteriaceae which is a part of the human normal flora but also are commonly associated with urinary tract infections which sometimes develops into to sepsis. Extended Spectrum β-Lactamases (ESBLs) are enzymes with hydrolytic abilities acting on β-lactam antibiotics, expressed by Enterobacteriaceae. The qualitative, Matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) can be used to detect chemical compounds in the ratio of mass to charge in accordance to their molecular weight. Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS) is a highly sensitive two-step method of quantification which first separate molecules by their polarity attraction force and then by the ratio of mass to charge. Aim The aim of this study was to develop a fast and efficient method to determine degradation of piperacillin-tazobactam and cefotaxime in blood plasma by LC-MS/MS. Method Tenfold dilution of piperacillin-tazobactam in concentrations of 2000 to 2 µg/ml, and cefotaxime in concentrations of 500 to 0,5 µg/ml where analyzed by MALDI-TOF MS, intact and also with the bacteria E. coli and K. pneumoniae with different expression of antibiotic resistance. Optimized concentrations where fixed in blood plasma and then quantified by LC-MS/MS. Result The detection limit by using MALDI TOF MS of hydrolyzed as well as non-hydrolyzed piperacillin-tazobactam was 20/2,5 µg/ml. The detection limit in cefotaxime was 5 µg/ml. Hydrolysis could not be detected in clinically fixed blood concentrations. Detection and quantification of hydrolysis by LC-MS/MS was possible in a concentration of three bacteria colonies/50 µl. Conclusion It is possible to detect hydrolysis in both MALDI TOF MS and LC-MS/MS. A larger amount of bacteria than expected was needed to demonstrate hydrolysis In LC-MS/MS.

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Huang, Huan. "Optimizing Deposition of Matrix and Ionization Salt via Two-Step Sublimation in Sample Preparation for Surface-Layer Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry Imaging (SL-MALDI-TOF MSI)." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1619183035472425.

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Guerreiro, Tatiane Melina 1987. "Análise de marcadores químicos de adulteração de vinagre balsâmico por 'silica plate laser desorption/ionization mass spectrometry' (SP-LDI-MS)." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/313028.

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Orientador: Rodrigo Ramos Catharino
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
Made available in DSpace on 2018-08-26T18:57:06Z (GMT). No. of bitstreams: 1 Guerreiro_TatianeMelina_M.pdf: 2016380 bytes, checksum: ef19a1e7b43ddd65fdb309939a8ceaf1 (MD5) Previous issue date: 2015
Resumo: O Vinagre Balsâmico é um produto italiano de grande valor, bastante apreciado em todo o mundo devido ao seu sabor característico e aos seus potenciais benefícios à saúde. Ao longo dos últimos anos, diversos pesquisadores realizaram estudos que avaliaram a sua composição físico-química, microbiana e suas propriedades benéficas. Devido ao alto número de estudos que confirmam o seu caráter antioxidante e suas propriedades anti-hipertensivas e antiglicêmicas, o vinagre balsâmico é um produto alvo de fraudes e adulterações. Desta forma, há uma preocupação acerca dos balsâmicos autênticos, que possuam certificação tanto para sua origem (região ou país), como para suas condições de processamento, garantindo sua qualidade e originalidade. Por isso, o esforço para a redução de fraudes, bem como a garantia da qualidade dos balsâmicos são de grande interesse tanto para saúde do consumidor, quanto do ponto de vista econômico. Buscando encontrar estratégias analíticas confiáveis, capazes de avaliar rapidamente a qualidade do vinagre balsâmico, este trabalho emprega a técnica de Espectrometria de Massas por Ionização/Dessorção a Laser em Placa de Sílica (SP-LDI-MS) para a rápida caracterização química de amostras de vinagres balsâmicos comercial e com indicação geográfica protegida (IGP), e identificação de suas amostras adulteradas com vinagres de baixo custo, provenientes de maçã, álcool e vinhos branco e tinto
Abstract: The Balsamic Vinegar is a valuable Italian product, very popular worldwide due to its distinctive flavor and potential health benefits. Several studies have been conducted to assess physicochemical and microbial compositions as well as with respect to its beneficial properties. Due to the high number of studies that confirm its antioxidant character and their antihypertensive and antiglycemic properties, balsamic vinegar is a potential target for frauds and adulterations. Thus, there is growing concern about the search for authenticated balsamics, so make sure your origin (region or country) as well as their processing conditions, which guarantee quality and originality of balsamic vinegar. Striving for fraud reduction and ensuring the quality and safety of food through reliable analytical strategies to quickly assess the quality of balsamic vinegar are of great interest to health and the economic point of view. In this context, this work employs the technique of Silica Plate Laser Desorption/Ionization Mass Spectrometry (SP-LDI-MS) for rapid chemical characterization of samples of commercial balsamic vinegars and with protected geographical indications (PGI) and identification their samples adulterated with inexpensive vinegars from apple, alcohol and red and white wines
Mestrado
Fisiopatologia Médica
Mestra em Ciências

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Ochoa, Mariela L. "Forensic and Proteomic Applications of Thermal Desorption Ion Mobility Spectrometry and Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry." Ohio University / OhioLINK, 2005. http://www.ohiolink.edu/etd/view.cgi?ohiou1113585811.

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Saad, Bessem. "Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry som verktyg för att detektera nedbrytning av Ceftolozan/Tazobaktam orsakad av karbapenemaser." Thesis, Örebro universitet, Institutionen för hälsovetenskaper, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-84598.

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Under senare år har en särskilt hög resistensutveckling observerats hos gramnegativa bakterier inom familjen Enterobacteriaceae. Den främsta resistensmekanismen utgör produktion av så kallade "extended-spectrum β-lactamases" (ESBL) och särskilt oroväckande är karbapenemaser (ESBLCARBA) som har förmåga att bryta ner ett flertal olika grupper av β-laktamantibiotika. Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) har utforskats som metod för snabb detektion av karbapenemasaktivitet genom analys av nedbrytning av antibiotika. Syftet med denna studie var att utvärdera om MALDI-TOF MS kan användas som metod för att detektera enzymatisk nedbrytning av Ceftolozan/Tazobaktam samt att undersöka vilka enzymer som uppvisar nedbrytning av antibiotikan. Sju karbapenemasproducerande isolat och en β-laktamasnegativ kontrollstam användes i studien. Isolaten inkuberades 120 min respektive 270 min med antibiotika (1mg/ml) i en buffertlösning (0,08% ammoniumbikarbonat, pH 8). Efter centrifugering analyserades supernatanten med MALDI-TOF MS. Nedbrytning av Ceftolozan detekterades hos samtliga karbapenemasproducerande stammar, utom hos E. coli med NDM-1 produktion. Nedbrytningstoppar av Tazobaktam detekterades emellertid enbart hos stammar med OXA-48 och NDM-7 produktion. Tydligast nedbrytning sågs efter 120 min. För tydligare visualisering av nedbrytningstoppar bör metoden dock optimeras med avseende på matrix, buffert och antibiotikakoncentration.
In recent years, an alarming increase of antibiotic resistance has been observed in Gram-negative bacteria, classified in the family Enterobacteriaceae. The main resistance mechanism is the production of extended-spectrum β-lactamases (ESBL). Particularly worrisome is the production of carbapenemases (ESBLCARBA) due to their ability to hydrolyze a broad range of β-lactams. Recently, Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) has been investigated as a method for rapid detection of carbapenemase activity through observation of antibiotic degradation. The aim of this study was to investigate whether MALDI-TOF MS can be used as a method to detect degradation of Ceftolozane/Tazobactam as well as to examine which enzymes that possess the ability to hydrolyze the antibiotic. A total of seven carbapenemase-producing strains were used in the study. The experiment also included a β-lactamase-negative isolate as a negative control. The strains were incubated with antibiotic (1mg/ml) in a buffered solution (0,08% ammonium bicarbonate, pH 8) for 120 min and 270 min. The supernatant, after centrifugation, was analyzed by MALDI-TOF MS. All the carbapenemase-producing strains demonstrated hydrolysis of Ceftolozane, except for NDM-1 producing E. coli. However, mass peaks corresponding to the degradation of Tazobactam were only detected in strains producing OXA-48 and NDM-7. The degradation of Ceftolozane/Tazobactam was most apparent after 120 minutes. However, to better enable detection of mass peaks, further optimization is needed in regard to appropriate matrix, buffer and antibiotic concentration.

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Chen, Ping. "Applications of Chemometric Algorithms to Ion Mobility Spectrometry and Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry." Ohio University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1206019463.

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Tate, Wendy Rose. "Surface-enhanced laser desorption/ionization time-of-flight mass spectroscopy (SELDI-TOF-MS) as a tool for molecular endpoint analysis of PX-12, a thioredoxin-1 inhibitor." Thesis, The University of Arizona, 2005. http://hdl.handle.net/10150/291852.

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Thioredoxin-1 is a redox protein upregulated in many cancers. Its functions include inhibition of apoptosis, increasing cellular growth and proliferation. It has been shown that cells displaying increased levels of Trx-1 have increased drug resistance. PX-12 is a Trx-1 inhibitor that shows anti-proloferative and cytotoxic activity in vitro and in vivo. We used surface enhanced laser desorption/ionization time-of-flight mass spectroscopy (SELDI-TOF-MS) to measure plasma Trx-1 levels of patients treated with PX-12 as a side study of a phase-I trial. SELDI-TOF-MS was able to measure a decrease in plasma Trx-1 after PX-12 treatment semi-quantitatively. In addition, SELDI measured 57 other protein peaks in plasma; seven which were found in all plasma samples analyzed. One of these peaks was located at 13.86kDa and identified through LC-MS/MS sequencing to be a variant of Transthyretin. Further studies into these additional peaks are necessary to determine their biological importance in relation to Trx-1 and PX-12.

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Åminne, Ann. "Evaluation of preanalytic methods in order to shorten the processing time before identification of fungal microorganisms by the MALDI-TOF MS." Thesis, Uppsala universitet, Institutionen för kvinnors och barns hälsa, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-255132.

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Identification of fungi is based on macroscopic observations of morphology and microscopic characteristics. These conventional methods are time-consuming and requires expert knowledge. For the past years Matrix-assisted laser desorption ionization-time of flight mass spectrometry has been used for routine bacterial identification in clinical laboratories but not yet in the same extension for fungi. In this study three preanalytic preparation methods for fungi were evaluated in order to shorten the processing time in routine laboratory performance. Clinically relevant strains (n=18) of molds and dermatophytes were cultivated on agar plates and prepared according to the different preparation methods for protein extraction. Each strain was analyzed in quadruplicate by the MALDI Biotyper and the database Filamentous Fungi Library 1.0. The results showed that the genus and species identification rates of the least time-consuming direct extraction method were 33% and 11% respectively. Using the formic acid extraction method, the genus and species identification rates were 83% and 44%, respectively. For the longest sample preparation method, liquid media culturing before formic acid extraction, successfully identified all strains except one, which resulted in an identification rate of 94% and 78% respectively. This study shows that preparing samples in cultured liquid media MADLI-TOF MS effectively identified fungal strains to both genus- and species-level. This method was however too time-consuming and cumbersome to be recommended as a replacement to the conventional method. Future studies should be aimed at expanding the reference library and making the direct extraction method more reproducible in terms of obtaining more reliable identification rates.

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Osterhage, Katharina Johanna [Verfasser]. "Die Zuverlässigkeit von MALDO-TOF MS (Matrix Assisted Laser Desorption / Ionization Time-of-Flight Mass Spectrometry) als Verfahren zur Identifikation von Acinetobacter spp. [[Elektronische Ressource]] / Katharina Johanna Osterhage." Köln : Deutsche Zentralbibliothek für Medizin, 2010. http://d-nb.info/1000932451/34.

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Rettinger, Anna Lena. "Anwendbarkeit der Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) für den Nachweis und die Differenzierung von Leptospira spp. im Vergleich zum Multilocus Sequence Typing (MLST)." Diss., lmu, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-154644.

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Jung, Seokwon. "Surface characterization of biomass by imaging mass spectrometry." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45906.

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Lignocellulosic biomass (e.g., non food-based agricultural resides and forestry wastes) has recently been promoted for use as a source of bioethanol instead of food-based materials (e.g., corn and sugar cane), however to fully realize these benefits an improved understanding of lignocellulosic recalcitrance must be developed. The primary goal of this thesis is to gain fundamental knowledge about the surface of the plant cell wall, which is to be integrated into understanding biomass recalcitrance. Imaging mass spectrometry by TOF-SIMS and MALDI-IMS is applied to understand detailed spatial and lateral changes of major components in the surface of biomass under submicron scale. Using TOF-SIMS analysis, we have demonstrated a dilute acid pretreated poplar stem represented chemical differences between surface and bulk compositions. Especially, abundance of xylan was observed on the surface while sugar profile data showed most xylan (ca. 90%) removed from the bulk composition. Water only flowthrough pretreated poplar also represented difference chemistry between surface and bulk, which more cellulose revealed on the surface compared to bulk composition. In order to gain the spatial chemical distribution of biomass, 3-dimensional (3D) analysis of biomass using TOF-SIMS has been firstly introduced in the specific application of understanding recalcitrance. MALDI-IMS was also applied to visualize different molecular weight (e.g., DP) of cellulose oligomers on the surface of biomass.

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Jacksén, Johan. "Improved techniques for CE-MALDI-MS off-line coupling and MALDI-MS analysis of primarily hydrophobic proteins and peptides." Licentiate thesis, KTH, Chemistry, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4599.

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Due to the hydrophobic nature of integral membrane proteins (IMP) they give rise to several difficulties concerning handling and analysis, which is not the case for the most water soluble proteins. New analysis methods are needed, where the insolubility problems of the hydrophobic proteins due to aggregation and adhesion are tackled. Those problems also affect digestion performance and equipment compatibility for the analysis.

Protocols for analysis and separation specified for IMP are presented in Paper I and III.

The instrumentation used in this work was capillary electrophoresis (CE) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Both instruments are suitable for peptide/proteins analysis.

In Paper I, protocols for a CE separation of bacteriorhodopsin (BR) peptides as model IMP peptides are established. Also, a partially automated manufacturing procedure of a concentration MALDI-target is presented, suitable for fractions from CE. The MS analysis detected 9 out of 10 cyanogen bromide (CNBr) digested BR peptides. A novel technique for the off-line integration of CE to MALDI-MS using a closed-open-closed system is presented in Paper II, where the open part is a microcanal functioning as a MALDI target window. Investigation of the microcanal electro-osmotic flow (EOF) properties and band broadening characteristics was performed. A protein separation was obtained and detected with MALDI-MS analysis in the microcanal. Different protein digestion methods were evaluated using BR in Paper III through MALDI-MS. Several digestion methods as well as MS media were investigated alongside different MALDI matrices. For example, matrices as the hydrophobic 2,6-dihydroxyacetophenone (DHAP) and 2-Hydroxy-3-methoxybenzoic acid (2H3MBA) or 2-Hydroxy-5-methoxybenzoic acid (2H5MBA) mixed with DHB, appeared to be promising matrices for analysis of BR.

Med anledning av integrala membranproteiners (IMP) hydrofoba egenskaper uppstår flera svårigheter vid hantering och analys av IMP, vilket inte är fallet för vattenlösliga proteiner. Nya analysmetoder krävs, som löser löslighetsproblemen för de hydrofoba proteinerna som tex flockning och adsorbtion. Dessa problem påverkar även klyvningsgrad och kompatibilitet med analysutrustningen.

I Artikel I och Artikel III presenteras protokoll för analys och separation specifikt för IMP. Instrumenteringen som har använts i detta arbete är kapillärelektrofores (CE) och matris-assisterad laserdesorptions-joniserings-masspektrometri (MALDI-MS). Båda instrumenten är lämpade för peptid/protein analyser.

I Artikel I, presenteras protokoll för en CE separation av peptider från bacteriorhodopsin (BR), som användes som modellpeptider för IMP. En delvis automatiserat tillverkningsprocedur för en koncentrerande MALDI-platta, som är anpassad för CE fraktionerna beskrivs också. MS-analysen detekterade 9 av 10 BR-peptider från cyanobromid-klyvning (CNBr). En ny teknik för off line-integrering av CE till MALDI-MS genom ett slutet-öppet-slutet system presenteras i Artikel II, där den öppna delen är en mikrokanal som fungerar som detektionsfönster i MALDI. Undersökning av mikrokanalens egenskaper som tex det elektroosmotiska flödet (EOF) och bandbreddningen utvärderades. En proteinseparation genomfördes och detekterades med MALDI–MS i mikrokanalen. Olika proteinklyvningsmetoder för BR undersöktes i Artikel III med MALDI-MS. Flera proteinklyvningsmetoder samt MS-medier utvärderades tillsammans med olika MALDI-matriser. Den hydrofoba matrisen 2,6-dihydroxyacetophenone (DHAP) och 2-Hydroxy-3-methoxybenzoic acid (2H3MBA) eller 2-Hydroxy-5-methoxybenzoic acid (2H5MBA) blandade med DHB, visade sig exempelvis vara lovande matriser för BR-analyser.

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Rettinger, Anna Lena [Verfasser], and Reinhard [Akademischer Betreuer] Straubinger. "Anwendbarkeit der Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) für den Nachweis und die Differenzierung von Leptospira spp. im Vergleich zum Multilocus Sequence Typing (MLST) / Anna Lena Rettinger. Betreuer: Reinhard Straubinger." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2013. http://d-nb.info/1032862343/34.

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Jacksén, Johan. "Improved techniques for CE and MALDI-MS including microfluidic hyphenations foranalysis of biomolecules." Doctoral thesis, KTH, Analytisk kemi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-27342.

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In this thesis, improved techniques for biomolecule analysis using capillary electrophoresis (CE) and matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) and hyphenations between those have been presented.A pre-concentration method which is possible to apply in both techniques, has also been investigated. In this work the off-line MS mode has been used either in the form of fractionation (Paper I) or by incorporating the MALDI target in the CE separation system (Paper II).In Paper I, a protocol for CE-MALDI analysis of cyanogen bromide digested bacteriorhodopsin (BR) peptides as model integral membrane protein peptides were established. Also, an improved protocol for partially automated manufacturing of a concentration MALDI-target plate is presented. The design of the targets was suitable for the fractions from the CE. A novel technique for the integration of CE to MALDI-MS using a closed-open-closed system is presented in Paper II, where the open part is a micro canal functioning as a MALDI target window. A protein separation was obtained and detected with MALDI-MS analysis in the micro canal. A method has been developed for detection of monosaccharides originating from hydrolysis of a single wood fiber performed in a micro channel, with an incorporated electromigration pre-concentration step preceding CE analysis in Paper III. The pre-concentration showed to be highly complex due to the fact that several parameters are included that affecting each other. In Paper IV a protocol using enzymatic digestion, MALDI-TOF-MS and CE with laser induced fluorescence (LIF) detection for the investigation of the degree of substitution of fluorescein isothiocyanate (FITC) to bovine serum albumin (BSA), as a contact allergen model system for protein-hapten binding in the skin, is presented. The intention of a further CE-MALDI hyphenation has been considered during the work. In Paper V 2,6-dihydroxyacetophenone (DHAP) was investigated, showing promising MALDI-MS matrix properties for hydrophobic proteins and peptides. 2,5-dihydroxybenzoic acid (DHB) was undoubtedly the better matrix for the hydrophilic proteins, but its performance for the larger and hydrophobic peptides was not optimal. Consequently, DHAP can be used as a compliment matrix for improved analysis of hydrophobic analytes.
QC 20101214

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Rogers, Kevin Shaun. "Laser desorption/laser ionization mass spectroscopy." Thesis, University of Salford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357037.

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Clipston, Nigel L. "Laser desorption/laser ionization Time-of-Flight Mass Spectrometry." Thesis, University of Salford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360476.

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Lu, Tian. "Nanomaterials For Liquid Chromatography and Laser Desorption/Ionization MassSpectrometry." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1376981440.

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Wen, Xiujuan. "Small Molecule Matrix-free Laser Desorption/ionization Mass Spectrometry." Thesis, The University of Arizona, 2006. http://hdl.handle.net/10150/193332.

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Modified Si wafers and nanoparticles (5-50 nm) have been developed and explored to assist laser desorption ionization mass spectrometry (LDI-MS) for small molecule analysis. DIOS (desorption/ionization on silicon) plates were prepared according to published protocols. DIOS was tested and compared with the optimized silicon nanoparticles derivatized by penterfluorophenylchlorosilane (PFP). SPALDI (Si nanoparticle assisted LDI) requires less laser flux than common MALDI and DIOS thus provides significant less background and higher ionization efficiency. It has higher surface homogeneity, relative salt tolerance and high selectivity which may origin from analyte dependent pre-charging. Surface characterization has been investigated. And different analytes including drugs, peptides, pesticides and acids in both biological and environmental samples have been applied by positive or negative ionization mode. Detection limits, down to the low femtomole per microliter levels have been achieved for propafenone and verapamil. SPALDI is an easily applicable practical tool at a potential low cost.

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Peng, Ivory Xingyu. "Electrospray-assisted laser desorption ionization mass spectrometry for proteomic studies." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1997571271&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.

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Berhane, Beniam T. "Rapid Characterization of Posttranscriptional Modifications in RNA Using Matrix Assisted Laser Desorption Ionization Mass Spectrometry and Matrix Assisted Laser Desorption Ionization Post Source Decay Mass Spectrometry." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1052319621.

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Miao, Zhixin. "Development and Applications of Liquid Sample Desorption Electrospray Ionization Mass Spectrometry (DESI-MS)." Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1347559532.

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Sproch, Norman K. "PDI-PIXE-MS: Particle Desorption Ionization Particle-Induced X-Ray Emission Mass Spectrometry." Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/194827.

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Incident ions, from a Van de Graaff accelerator, in the MeV energy range, deposit their energy into the near surface of a sample. This, in turn, causes atomic, molecular, cluster and fragment ion species to be desorbed and ionized, while simultaneously emitting characteristic elemental X-rays. The multielemental X-rays provide qualitative elemental information, which may be deconvoluted and fit to a theoretical X-ray spectrum, generated by a quantitative analysis program, GUPIX, while the atomic, molecular, cluster, and fragment ion species are identified using a quadrupole mass spectrometer. This methodology directly links elemental determinations with chemical speciation.The development of this particle desorption ionization particle induced X-ray emission mass spectrometer, the PDI-PIXE-MS (or PIXE-MS) instrument, which has the ability to collect both qualitative multielemental X-rays and mass spectral data is described. This multiplexed instrument has been designed to use millimeter-sized MeV particle beams as a desorption ionization (PDI) and X-ray emission (PIXE) source. Two general methods have been employed, one simultaneous and the other sequential. Both methods make use of a novel X-ray/ion source developed for use with the quadrupole mass spectrometer used in these experiments. The first method uses a MeV heavy ion particle beam, typically oxygen, to desorb and ionize the sample, while simultaneously producing characteristic multielemental X-rays. The resulting molecular, cluster, and fragment ions are collected by the mass spectrometer, and the X-rays are collected using a Si-PIN photodiode detector in conjunction with a multichannel analyzer (MCA). Heavy ions of N+, O+, O+2, Ar+, and Kr+ have been investigated, although heavy ion X-ray and mass spectra have focused on the use of oxygen particle beams. The second method is performed by first collecting the X-ray data with a MeV ion beam of He+ ions, then desorbing and ionizing the sample species with a MeV particle beam of heavy ions, producing good ion yields, for mass spectral data collection. The potential development of a scanning microprobe instrument, that would provide micron-scale, imaged, multielemental, and molecular and fragment ion chemical information is being investigated through the development of this prototype PIXE-MS instrument.

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Osterhage, Katharina Johanna. "Die Zuverlässigkeit von MALDO-TOF MS (Matrix Assisted Laser Desorption." Köln Deutsche Zentralbibliothek für Medizin, 2010. http://d-nb.info/1000932451/34.

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Dubois, Frédéric Dubois Frédéric. "Ion formation and detection in matrix-assisted laser desorption/ionization mass spectrometry /." [S.l.] : [s.n.], 1999. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13255.

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Dai, Yuqin. "Development of matrix-assisted laser desorption ionization mass spectrometry for biopolymer analysis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0003/NQ39519.pdf.

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Shariatgorji, Mohammadreza. "Novel clean-up, concentration and laser desorption/ionization strategies for mass spectrometry /." Stockholm : Department of Analytical Chemistry, Stockholm University, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-32236.

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Diss. (sammanfattning) Stockholm : Stockholms universitet, 2010.
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: In Press. Härtill 7 uppsatser.

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Dashtiev, Maxim. "Fluorescence spectroscopy of trapped molecular ions produced with matrix-assisted laser desorption/ionization /." Zürich : ETH, 2006. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=16949.

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35

Zhang, Hui. "Developments and applications of electrophoresis and small molecule laser desorption ionization mass spectrometry." [Ames, Iowa : Iowa State University], 2007.

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Akinapalli, Srikanth. "MICROFLUIDIC DYNAMIC ISOELECTRIC FOCUSING COUPLED TO MATRIX ASSISTED LASER DESORPTION/IONIZATION MASS SPECTROMETRY." OpenSIUC, 2016. https://opensiuc.lib.siu.edu/dissertations/1289.

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Proteomics is an increasingly important area of biological research and has gathered much attention over recent years. Major challenges that make a proteomic analysis difficult are sample complexity, diversity and dynamic range. Progress in the area of proteomics relies heavily on new analytical tools for the sensitive, selective, and high-throughput studies of target analytes. It is estimated that there are several hundred thousand proteins in a human cell. In order to be able to analyze such a complex sample, an analytical method must be capable of separating and detecting many different sample peaks. The complexity of such samples indicates that a single separation method will not be able to provide the needed resolution. If two methods that are orthogonal are combined, then the peak capacity of the combined system is the product of the two individual peak capacities. Development of such systems would cater to the current demands of proteomics studies. Matrix assisted laser desorption/ionization (MALDI) mass spectrometry has evolved into a primary analytical tool for proteomics research. MALDI is fast and efficient and has a high tolerance to non-volatile buffers and impurities. The samples for MALDI are typically applied to solid supports after having been subjected to off-line liquid or gel separations. Several methods have been reported involving various chromatographic or electrophoretic separation methods. However, the current methods often require highly sophisticated sample handling systems, which are often expensive and in need of skilled human resources. The current demands of proteomic analyses require fast, efficient and inexpensive methods for separation to fully harness the capability of MALDI mass spectrometry. In this work a microfluidic device has been designed to perform dynamic isoelectric focusing (DIEF) based protein separation with digital sample deposition directly on a MALDI target for offline analysis. DIEF is related to capillary isoelectric focusing which and can facilitate the interface without the loss of the separation resolution. Compared to traditional capillary isoelectric focusing (cIEF) DIEF uses additional high-voltage power supplies to control the pH gradient by manipulating the electric field. The proteins can be focused at a desired sampling position according to their isoelectric point, to be collected for further analysis by MALDI mass spectrometry. DIEF has a peak capacity of over a thousand and offers an ease of interfacing to other techniques making it a preferred separation method for the interface with mass spectrometric techniques such as MALDI. The design of the microfluidic device is based on a digital droplet fractionation. Multiple fractions of the sample solution from DIEF are generated to retain the resolution and to act as an additional separation mode. The microfluidic device is controlled by actuating pneumatic valves built into the device. The DIEF operational parameters were optimized according to the surface functionality and the design of the microfluidic device. A suitable MALDI sample preparation method was found by studying different existing methods. The methods were studied using test proteins prepared in solutions having the additives used in the experiment. A simple mixture of three proteins was used to demonstrate the application of the developed method. The separation between the proteins insulin, hemoglobin and the myoglobin was demonstrated by varying the separation resolution in three experiments.

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Xiang, Fan. "Improvement and investigation of sample preparation for matrix-assisted laser desorption/ionization of proteins." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq25780.pdf.

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38

Wang, Jian. "Analyses of food and feed compounds using matrix-assisted laser desorption/ionization mass spectrometry." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0013/NQ59690.pdf.

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39

Liu, Qiang. "Fundamental Study and Method Development for Surface-based Laser Desorption Ionization Imaging Mass Spectrometry." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-02262009-143514/.

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By providing both the chemical identity and the spatial organization of each component in biological samples, Imaging Mass Spectrometry (IMS) becomes an emerging tool in clinic and pharmacological study. Most work in IMS has been focused on protein and peptide mapping in biological samples to take advantage of effective analyte ionization in MALDI-MS, and also partially due to the limitation of MALDI-MS in small molecule detection. The focus of my research is to develop novel tools to image spatial distribution of small molecules in biological samples. A surface-based mass spectrometric imaging method, i.e. Desorption/Ionization on Silicon (DIOS), was used for biological surface analysis in the concept-proof investigation. More over, possible proton transferring pathways and impact of local chemical environment have been systematically investigated in the fundamental understanding of ionization mechanism of SALDI-MS. Based on the finding on the SALDI mechanism, a hybrid ionization approach, ME-SALDI has been developed by combing the strength of the conventional MALDI matrix and SALDI, where the improved detection sensitivity with reduced matrix-analyte interference and the improved imaging capability through analysis of mouse brain and heart sections has been demonstrated. In addition, the impact of vacuum stability of matrix in ME-SALDI-IMS applications has been examined. A solvent free, homogenous and reproducible sublimation method has been developed for ionic matrix in ME-SALDI, by which improved vacuum stability and MS detection have been achieved. Furthermore, a new generation of meso-porous oxide substrate was developed as a novel ME-SALDI substrate with a superior storage stability, extended detectable mass range and robust substrate preparation.

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Busse, Frederik [Verfasser], and R. J. Dwayne [Akademischer Betreuer] Miller. "Mechanisms of Picosecond Infrared Laser Desorption Ionization / Frederik Busse ; Betreuer: R. J. Dwayne Miller." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2019. http://d-nb.info/1192912977/34.

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41

Köchling, Heinrich J. (Heinrich Josef) 1962. "Advancements in matrix-assisted laser desorption ionization mass spectrometry of peptides, proteins and polymers." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/10020.

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42

Mowat, Ian A. "Synthetic polymer analysis using matrix assisted laser desorption/ionization time-of-flight mass spectrometry." Thesis, University of Edinburgh, 1996. http://hdl.handle.net/1842/12128.

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The aim of the work described in this thesis was to assess 'Matrix Assisted Laser Desorption/Ionization' (MALDI) Time-of-Flight mass spectrometry as a possible technique for the analysis of synthetic polymers. A compact home-built time-of-flight mass spectrometer of cylindrically symmetrical geometry was used to carry out all the mass spectrometry detailed described in this thesis. A survey of the literature describing the development of matrix assisted laser desorption/ionization spectrometry and also the previous analysis of polymers by laser mass spectrometry was carried out. Experiments comparing the performance of the apparatus with published data on peptides and proteins were carried out, followed by experiments to assess the possibility of analyzing synthetic polymers. Initially polar polymers were investigated, since they could be anlayzed using sample preparations very similar to those developed for peptide and protein analysis. Later investigations were carried out on non-polar polymers such as polystyrene. The attachment of a range of transition metals to a low mass polystyrene was investigated using laser desorption/ionization time-of-flight mass spectrometry, without the use of matrices to increase the ion yield. Systematic investigations into the effects of sample spot composition, i.e. the amounts of matrix, polymer and salt present, were carried out, and used to suggest possible models for the processes leading to the generations of large gas phase ions. The effects of sample spot composition on the size and shape of the polymer molecular weight distributions obtained was also investigated. Liquid polymers such as polysiloxanes and perfluorinated polyethers were investigated using laser desorption/ionization and matrix assisted laser desorption/ionization. Carbon cluster generation from such polymers was investigated, and fullerene and polycyclic aromatic hydrocarbon analysis was also briefly studied. Novel new molecules such as aryl ester dendrimers were investigated, since they could not be successfully analyzed by other mass spectrometric techniques. Single molecular ions were obtained, helping to confirm the expected masses of these molecules. Novel new polymers such as hyperbranched aromatic polyesters were also analyzed, and molecular weight distributions were successfully obtained for a number of samples, showing the utility of MALDI for the analysis of new materials.

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Mazarin, Michaël. "L'ionisation MALDI [Matrix assisted laser desorption/ionization] de polymères synthétiques en spectrométrie de masse." Aix-Marseille 1, 2008. http://theses.univ-amu.fr.lama.univ-amu.fr/2008AIX11034.pdf.

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La spectrométrie de masse après ionisation/désorption laser assistée par matrice (MALDI) apparaît comme une technique de choix pour la caractérisation structurale des polymères synthétiques. Néanmoins, parce que les processus fondamentaux qui régissent la technique MALDI sont encore mal connus, l’optimisation des conditions expérimentales reste empirique. L’objectif de ces travaux de thèse est d’utiliser conjointement des techniques de spectrométrie de masse et de résonance magnétique nucléaire (RMN) pour rationaliser les méthodologies d'analyse des polymères synthétiques par MALDI. Une première approche consiste à utiliser la RMN diffusionnelle pour pré-évaluer la masse moyenne des polymères, valeur qui sert ensuite de guide pour la préparation des dépôts MALDI et l’interprétation des données spectrales obtenues. Un deuxième axe de recherche s’intéresse à la fragilité des groupements terminaux des macromolécules synthétisées par polymérisation radicalaire contrôlée. Les mécanismes de rupture de ces groupements pendant l’ionisation MALDI ont été élucidés en combinant des expériences de dissociation induite par collision après ionisation electrospray, des expériences de RMN en phase liquide et des calculs théoriques. Il ressort de cette étude que seule la protonation du groupement fragile permet la production d’ions oligomères intacts. A cet effet, une préparation sans solvant des dépôts MALDI a été développée pour promouvoir la protonation des macromolécules étudiées. Son efficacité reste néanmoins limitée aux polymères de faible taille. Enfin, le potentiel de la RMN du solide pour caractériser la microstructure des dépôts MALDI a été évalué
Matrix assisted laser desorption/ionization (MALDI) mass spectrometry is a key technique for synthetic polymer structural characterization. Nevertheless, because fundamental process of MALDI is still not fully understood, no standard protocol is available and experimental conditions are empirically optimized. The aim of this PhD work is to combine mass spectrometric techniques with nuclear magnetic resonance (NMR) spectroscopies to develop rationalized MALDI methodologies for structural studies of synthetic polymers. A first approach consists of using diffusion NMR for a rapid evaluation of polymer average mass, to be further used as a guideline in MALDI sample preparation and spectral data interpretation. A second axis deals with fragile end-groups of macromolecules synthesized via controlled radical polymerization reactions. Combining collision-induced dissociation of electrosprayed oligomers with liquid state NMR and theoretical calculations allowed the elucidation of mechanisms involved in the bond cleavage which is observed to occur within such end-groups during the MALDI process. This study shows that protonation of the fragile termination is the main way to allow intact oligomer ions to be produced. A solvent-free MALDI sample preparation was thus developed to promote macromolecule protonation but its efficiency was shown to be limited to the case of small polymers. Finally, the potential of solid state NMR to characterize the microstructure of MALDI sample was evaluated

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44

Garrett, Timothy J. "Imaging small molecules in tissue by matrix-assisted laser desorption/ionization tandem mass spectrometry." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0013807.

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45

Priyasantha, Kandalama KD. "DEVELOPMENT OF A NOVEL MATRIX ASSISTED LASER DESORPTION / IONIZATION (MALDI) BASED PEPTIDE QUANTITATION APPROACH." OpenSIUC, 2015. https://opensiuc.lib.siu.edu/dissertations/989.

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Matrix Assisted Laser Desorption / Ionization (MALDI) Mass Spectrometry (MS) has emerged as an important tool in the field of proteomics mainly because it is simple, quick and efficient. The identification and quantitation of biomarkers, protein targets for drugs, and metabolites are some of the important fields in proteomics research. Although MALDI MS is an important tool in proteomics research there are drawbacks of the technique that need further development in order for the approach to be used in clinical laboratories. One major limitation of MALDI MS is the generally poor reproducibility of ion signal intensities, which negatively impacts the quantitation of peptides and protein by MALDI MS. A considerable amount of research has been performed in an effort to improve the ion signal reproducibility in MALDI MS. However, many of the approaches developed have introduced specific drawbacks with respect to the traditional dried-droplet sample preparation technique, negating many of the advantages of the MALDI MS approach. This project has focused on the development of a novel approach to quantify peptides by MALDI MS while preserving traditional known advantages of the technique. The studies performed show that an approach in which the ion signal base widths are manipulated to match that of a reference ion signal, through adjustments in desorption laser intensity, leads to much higher reproducibility in the integrated ion signal intensities. A standard curve acquired using the constant ion signal base width approach showed lower average RSDs (< 10.00% vs.> 39.00%) and improved R2 values (> 0.9600 vs. < 0.809) as compared to the conventional constant desorption laser intensity approach. Subsequent work also revealed that the peptide hydrophobic / hydrophilic properties influenced the applicability of the quantitation approach to mixtures of peptides. Specifically, the data revealed that peptides with differing hydrophobic / hydrophilic properties appear to co-crystallize with the MALDI matrix differently leading to an inability to use a hydrophobic peptide signal to quantitate a hydrophilic peptide, and vice versa. This latter conclusion was further supported in similar studies performed on the mixture of peptides resulting from tryptic digestion of the protein bovine serum albumin.

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46

Astorga-Wells, Juan. "Microfluidic electrocapture technology in protein and peptide analysis /." Stockholm, 2004. http://diss.kib.ki.se/2004/91-7349-965-x/.

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Erb, William Joseph Owens Kevin G. "Exploration of the fundamentals of matrix assisted laser desorption/ionization time-of- flight mass spectrometry /." Philadelphia, Pa. : Drexel University, 2007. http://hdl.handle.net/1860/1765.

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48

Tang, Ho-wai, and 鄧浩維. "Studies on surface-assisted laser desorption/ionization and its analytical application in imaging mass spectrometry." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47145559.

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Surface-Assisted Laser Desorption/Ionization Mass Spectrometry (SALDI-MS) is an analytical technique enabling direct chemical analysis of solid samples. Analytes could be desorbed/ionized upon nitrogen laser irradiation from a SALDI substrate-coated sample, then analyzed by MS. The substrate is involved in the transfer of laser energy to the analytes, and eventually assists the desorption/ionization of analytes. The analytical performance of SALDI-MS, such as detection sensitivity, is dependent on different parameters of the substrate, such as size, morphology and form. In this thesis, the effects of several substrate parameters on the SALDI process were investigated. SALDI-MS based Imaging Mass Spectrometry (IMS) method was also developed using efficient SALDI substrate identified in the fundamental studies. IMS is a chemical-specific mapping technique which allows parallel mapping of multiple analytes in solid samples. The desorption mechanism of SALDI is investigated using two groups of substrate, the carbon allotropes and the noble metal nanoparticles. Ion desorption efficiency and internal energy transfer were probed and correlated in carbon-based SALDI. It was found that the ion desorption efficiency and internal energy transfer was in opposite order. Substrate that transferred more internal energy to ions did not show higher ion desorption efficiency. This result could not be explained by the Thermal Desorption model which was a generally believed mechanism of the SALDI desorption process. A non-thermal model, the Phase Transition model is proposed to account for the SALDI desorption process. The Phase Transition model suggests that the substrate is melted/ restructured upon laser irradiation, and this will assist ion desorption. The Phase Transition model is supported by the morphological change of carbon substrates after SALDI and high initial velocity of ions desorbed by carbon-based SALDI (> 1,000 ms-1). SALDI-MS is useful for small molecule analysis due to the relatively clean background in the low mass region. SALDI-IMS is developed and applied to the imaging of spatial distribution of small molecules in forensic and biological samples. Gold nanoparticles (AuNPs) was selected as the substrate from several other noble metal NPs. A solvent-free method, argon ion sputtering, was employed for coating AuNPs on sample surface prior to SALDI-IMS analysis. Fine details of the samples, such as the fine pattern of latent fingerprints and handwriting on questioned documents can be preserved and imaged reliably by avoiding the use of solvent. Fatty acids, drugs and ink components can be imaged in forensic samples including latent fingerprints, banknotes and checks. The solvent-free SALDI-IMS method was also applied to image the distribution of metabolites in intact animal tissues. Spatial distributions of neurotransmitters, nucleobases and fatty acids can be imaged from mouse brain and tumor tissue sections.
published_or_final_version
Chemistry
Doctoral
Doctor of Philosophy

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Smith, Donna M. "Matrix Assisted Laser Desorption Ionization Quadrupole Time-of-Flight Mass Spectrometry of Poly(2-Vinylpyridine)." University of Akron / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1110337309.

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Fiorentino, Michael Armond. "Immediate observation of matrix assisted laser desorption ionization products in a Fourier transform mass spectrometer /." Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004264.

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Dissertations / Theses on the topic 'Laser desorption ionization MS'

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