Ionization Mass Spectrometry (ionization + mass_spectrometry)

Distribution by Scientific Domains
Distribution within Chemistry

Kinds of Ionization Mass Spectrometry

  • atmospheric pressure chemical ionization mass spectrometry
  • chemical ionization mass spectrometry
  • chromatography electrospray ionization mass spectrometry
  • chromatography ionization mass spectrometry
  • desorption electrospray ionization mass spectrometry
  • electron ionization mass spectrometry
  • electrospray ionization mass spectrometry
  • high-performance liquid chromatography ionization mass spectrometry
  • laser ionization mass spectrometry
  • liquid chromatography electrospray ionization mass spectrometry
  • liquid chromatography ionization mass spectrometry
  • matrix-assisted laser ionization mass spectrometry
  • nano-electrospray ionization mass spectrometry
  • pressure chemical ionization mass spectrometry

  • Selected Abstracts

    The Detection of Multiply Charged Dyes Using Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry for the Forensic Examination of Pen Ink Dyes Directly from Paper

    Jamie D. Dunn M.S.
    Abstract:, Laser desorption mass spectrometry (LDMS) is emerging as a technique for questioned document examination. Its use is limited to detecting ink dyes that are neutral or singly charged. Several inks contain dyes that are multiply charged and LDMS cannot be employed for their identification. We have successfully detected >20 polyionic dyes that can be used in the manufacture of inks using matrix-assisted laser desorption/ionization (MALDI) MS, directly from paper, with the matrix, 2-(4-hydroxyphenylazo)benzoic acid (HABA), and the additive, diammonium hydrogen citrate (DAHC). For example, Acid Violet 49, a charged dye containing one positively-charged site and two negatively charged sulfonate groups, cannot be detected by LDMS, but forms intact, singly charged ions in the MALDI MS experiment. The method described is also useful for identifying multiply charged dye mixtures that are used in modern pen inks. [source]

    Application of Electrospray Ionization Mass Spectrometry to the Elucidation of the Primary Structure of Lignin

    Dmitry V. Evtuguin
    Abstract Electrospray ionization mass spectrometry (ESI-MS) was successfully applied to the structural analysis of lignin. The structure of oligomers fractionated from Eucalyptus globulus dioxane lignin was elucidated using tandem mass spectrometry, and the information on fragmentation patterns was provided by experiments on dimeric model compounds. Data obtained revealed a significant abundance in the lignin macromolecules of linear fragments that were composed of 8- O -4,-linked syringyl/guaiacyl units and syringaresinol. The proposed linear fragment of the E. globulus lignin molecule. [source]

    Innentitelbild: Sensitive Detection of Native Proteins Using Extractive Electrospray Ionization Mass Spectrometry (Angew. Chem.

    ANGEWANDTE CHEMIE, Issue 17 2010
    Die Charakterisierung nativer Proteine gelingt durch extrahierende Elektrosprayionisations-Massenspektrometrie (EESI-MS). Wie H. Chen und Mitarbeiter in ihrer Zuschrift auf S.,3117,ff. ausführen, werden native Proteine bei der EESI mit Ladungen belegt, ohne dass ein starkes elektrisches Feld benötigt wird. Das Verfahren erleichtert massenspektrometrische Studien, auch an biologischen Rohproben, und vermeidet signifikante Konformationsänderungen und Aktivitätsverluste. [source]

    Sensitive Detection of Native Proteins Using Extractive Electrospray Ionization Mass Spectrometry,

    ANGEWANDTE CHEMIE, Issue 17 2010
    Huanwen Chen Prof.
    ,Sanfte" Ionisation: Bei der EESI werden Ladungen auf native Proteine übertragen, ohne sie einem starken elektrischen Feld auszusetzen. So lassen sich Proteine in nichtaufbereiteten biologischen Proben massenspektrometrisch charakterisieren, ohne dass bedeutende Konformationsänderungen oder Aktivitätsverluste eintreten. Die EESI-MS bietet sich für die Hochdurchsatzanalyse kleinster Proteinmengen unter nativen Bedingungen an. [source]

    Three-Dimensional Vizualization of Mouse Brain by Lipid Analysis Using Ambient Ionization Mass Spectrometry,

    ANGEWANDTE CHEMIE, Issue 5 2010
    Sehen, nicht vorstellen: Dreidimensionale Bilder können aus einem Satz von 2D-Daten konstruiert werden, die durch Desorptions-Elektrospray-Ionisations(DESI)-Massenspektrometrie erhalten wurden. Die 3D-Bilder zeigen die räumliche Verteilung bestimmter Biomoleküle in Substrukturen des Maushirns (siehe Bild). [source]

    Dilution-Free Analysis from Picoliter Droplets by Nano-Electrospray Ionization Mass Spectrometry,

    ANGEWANDTE CHEMIE, Issue 37 2009

    Verpackt, versandt und geliefert: Eine Methode wurde entwickelt, die den Inhalt wässriger Pfropfen, die in einer Ölphase immergiert sind, automatisch in eine wässrige Flussphase transferiert. Dies ermöglicht eine verdünnungslose Elektrospray(ESI)-Massenspektrometrieanalyse in der tröpfchenbasierten Mikrofluidik. [source]

    Probing the Subunit-Subunit Interaction of the Tetramer of E. coli KDO8P Synthase by Electrospray Ionization Mass Spectrometry,

    Zhili LI
    Abstract Escherichia coli 3-Deoxy- D - manno- octulosonate 8-phosphate (KDO8P) synthase catalyzes the condensation reaction between D -arabinose 5-phosphate (A5P) and phosphoenolpyruvate (PEP) to form KDO8P and inorganic phosphate (Pi). This enzyme exists as a tetramer in solution, which is important for catalysis. Two different states of the enzyme were obtained: i) PEP-bound and ii) PEP-unbound. The effect of the substrates and products on the overall structure of KDO8P synthase in both PEP-bound and unbound states was examined using electrospray ionization mass spectrometry. The analysis of our data showed that the complexes of the PEP-unbound enzyme with PEP (or Pi) favored the formation of monomers, while the complexes with A5P (or KDO8P) mainly favored dimers. The PEP-bound enzyme was found to exist in the monomer and dimer with a small amount of the tetramer, whereas the PEP-unbound form primarily exists in the monomer and dimer, and no tetramer was observed, suggesting that the bound PEP have a role in stabilization of the tetrameric structure. Taken together, the results imply that the addition of the substrates or products to the unbound enzyme may alter the subunit-subunit interactions and/or conformational change of the protein at the active site, and this study also demonstrates that the electrospray ionization mass spectrometric method may be a powerful tool in probing the subunit-subunit interactions and/or conformational change of multi-subunit protein upon binding to ligand. [source]

    A novel approach for analysis of oligonucleotide,cisplatin interactions by continuous elution gel electrophoresis coupled to isotope dilution inductively coupled plasma mass spectrometry and matrix-assisted laser desorption/ionization mass spectrometry

    ELECTROPHORESIS, Issue 7 2008
    Wolfram Brüchert
    Abstract In this work we present a novel approach for in vitro studies of cisplatin interactions with 8-mer oligonucleotides. The approach is based on the recently developed coupling of continuous elution gel electrophoresis (GE) to an inductively coupled plasma-sector field mass spectrometer (ICP-SFMS) with the aim of monitoring the interaction process between this cytostatic drug and the nucleotides. In contrast to existing methods, the electrophoretic separation conditions used here allow both the determination of the reaction kinetics in more detail as well as the observation of dominant intermediates. Two different nucleotides sequences have been investigated for comparison purposes, one containing two adjacent guanines (5,-TCCGGTCC-3,) and one with a combination of thymine and guanine (5,-TCCTGTCC-3,), respectively. In order to gain further structural information, MALDI-TOF MS measurements have been performed after fraction collection. This allows for identification of the intermediates and the final products and confirms the stepwise coordination of cisplatin via monoadduct to bisadduct formation. Furthermore, the ICP-MS results were quantitatively evaluated in order to calculate the kinetics of the entire process. [source]

    Electronic gel protein transfer and identification using matrix-assisted laser desorption/ionization-mass spectrometry

    ELECTROPHORESIS, Issue 9 2004
    Jonathan W. Cooper
    Abstract An electronic protein transfer technique is described for achieving the rapid and efficient recovery of sodium dodecyl sulfate (SDS)-protein complexes from polyacrylamide gels. This process involves the use of small-dimension capillaries in physical contact with a resolved protein band within the polyacrylamide gel, providing a large potential drop and high electric field strength at the capillary/gel interface. Several factors controlling the electronic protein transfer, including the applied electric field strength, the electrophoresis buffer concentration, and the capillary dimension, are studied to further enhance the use of field-amplification for sample stacking of extracted SDS-protein complexes. As a result of sample stacking, the extracted proteins from a 50 ng gel loading are present in a narrow (,80 nL) and highly concentrated (0.46 mg/mL or 3.3×10,5 M for cytochrome c) solution plug. Three model proteins with molecular mass ranging from 14 kDa (cytochrome c) to 116 kDa (,-galactosidase) are stained by Coomassie blue and electrophoretically extracted from gels with protein loadings as low as 50 ng. The capillary format of the electronic protein transfer technique allows direct deposition of extracted proteins onto a matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) target. Various matrices and solvent compositions are evaluated for the analysis of extracted and concentrated SDS-protein complexes using MALDI-MS. The electronic protein transfer technique, when operated under optimized conditions, is demonstrated for the effective (>70% recovery), speedy (less than 5 min), and sensitive MS identification of gel resolved proteins (as low as 50 ng). [source]

    A convenient purification and preconcentration of peptides with ,-cyano-4-hydroxycinnamic acid matrix crystals in a pipette tip for matrix-assisted laser desorption/ionization mass spectrometry,

    Helena, ehulková
    Abstract Peptide samples derived from enzymatic in-gel digestion of proteins resolved by gel electrophoresis often contain high amount of salts originating from reaction and separation buffers. Different methods are used for desalting prior to matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS), e.g. reversed-phase pipette tip purification, on-target washing, adding co-matrices, etc. As a suitable matrix for MALDI MS of peptides, ,-cyano-4-hydroxycinnamic acid (CHCA) is frequently used. Crystalline CHCA shows the ability to bind peptides on its surface and because it is almost insoluble in acidic water solutions, the on-target washing of peptide samples can significantly improve MALDI MS signals. Although the common on-target washing represents a simple, cheap and fast procedure, only a small portion of the available peptide solution is efficiently used for the subsequent MS analysis. The present approach is a combination of the on-target washing principle carried out in a narrow-end pipette tip (e.g. GELoader tip) and preconcentration of peptides from acidified solution by passing it through small CHCA crystals captured inside the tip on a glass microfiber frit. The results of MALDI MS analysis using CHCA-tip peptide preconcentration are comparable with the use of homemade POROS R2 pipette tip microcolumns. Advantages and limitations of this approach are discussed. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Tandem mass spectrometry of synthetic polymers

    Anna C. Crecelius
    Abstract The detailed characterization of macromolecules plays an important role for synthetic chemists to define and specify the structure and properties of the successfully synthesized polymers. The search for new characterization techniques for polymers is essential for the continuation of the development of improved synthesis methods. The application of tandem mass spectrometry for the detailed characterization of synthetic polymers using the soft ionization techniques matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and electrospray ionization mass spectrometry (ESI-MS), which became the basic tools in proteomics, has greatly been increased in recent years and is summarized in this perspective. Examples of a variety of homopolymers, such as poly(methyl methacrylate), poly(ethylene glycol), as well as copolymers, e.g. copolyesters, are given. The advanced mass spectrometric techniques described in this review will presumably become one of the basic tools in polymer chemistry in the near future. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Chemically modified porous silicon for laser desorption/ionization mass spectrometry of ionic dyes

    I. V. Shmigol
    Abstract Desorption/ionization on silicon (DIOS) mass spectra of model ionic dyes methylene blue (MB+Cl,) and methyl orange (Na+MO,) were studied using p+ type-derived porous silicon (PS) free layers. As-prepared PS (PS-H), the PS thermally oxidized at 300 °C (PS-OX), PS with chemically grafted cation-exchanging alkylsulfonic acid (PS-SO3H) and anion-exchanging propyl-octadecyldimethylammonium chloride (PS-ODMA+Cl,) groups was tested as ionization platforms. Two mechanisms of the methylene blue desorption/ionization were found: (1) the formation of [MB + H]+, ion due to the reduction/protonation of MB+, which is predominant for PS-H and PS-OX platforms and (2) direct thermal desorption of the MB+ cation, prevailing for PS-SO3H. The fragmentation of the cation is significantly suppressed in the latter case. The samples of PS-SO3H and PS-ODMA+ Cl, efficiently adsorb the dyes of the opposite charge from their solutions via the ion-exchange. Consequent DIOS MS studies allow to detect only low fragmented ions (MB+ and MO,, respectively), demonstrating the potential of the ion-exchange adsorption combined with DIOS MS for the analysis of ionic organic compounds in solutions. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Ionization efficiency of ,-helical peptides in laser desorption/ionization mass spectrometry

    Yasushi Shigeri

    The effect of temperature on the stability of compounds used as UV-MALDI-MS matrix: 2,5-dihydroxybenzoic acid, 2,4,6-trihydroxyacetophenone, ,-cyano-4-hydroxycinnamic acid, 3,5-dimethoxy-4-hydroxycinnamic acid, nor-harmane and harmane

    Olga I. Tarzi
    Abstract The thermal stability of several commonly used crystalline matrix-assisted ultraviolet laser desorption/ionization mass spectrometry (UV-MALDI-MS) matrices, 2,5-dihydroxybenzoic acid (gentisic acid; GA), 2,4,6-trihydroxyacetophenone (THA), ,-cyano-4-hydroxycinnamic acid (CHC), 3,5-dimethoxy-4-hydroxycinnamic acid (sinapinic acid; SA), 9H-pirido[3,4-b]indole (nor-harmane; nor-Ho), 1-methyl-9H-pirido[3,4-b]indole (harmane; Ho), perchlorate of nor-harmanonium ([nor-Ho + H]+) and perchlorate of harmanonium ([Ho + H]+) was studied by heating them at their melting point and characterizing the remaining material by using different MS techniques [electron ionization mass spectrometry (EI-MS), ultraviolet laserdesorption/ionization-time-of-flight-mass spectrometry (UV-LDI-TOF-MS) and electrospray ionization-time-of-flight-mass spectrometry (ESI-TOF-MS)] as well as by thin layer chromatography analysis (TLC), electronic spectroscopy (UV-absorption, fluorescence emission and excitation spectrosco y) and 1H nuclear magnetic resonance spectroscopy (1H-NMR). In general, all compounds, except for CHC and SA, remained unchanged after fusion. CHC showed loss of CO2, yielding the trans-/cis -4-hydroxyphenylacrilonitrile mixture. This mixture was unambiguously characterized by MS and 1H-NMR spectroscopy, and its sublimation capability was demonstrated. These results explain the well-known cluster formation, fading (vanishing) and further recovering of CHC when used as a matrix in UV-MALDI-MS. Commercial SA (SA 98%; trans -SA/cis -SA 5 : 1) showed mainly cis- to- trans thermal isomerization and, with very poor yield, loss of CO2, yielding (3,,5,-dimethoxy-4,-hydroxyphenyl)-1-ethene as the decarboxilated product. These thermal conversions would not drastically affect its behavior as a UV-MALDI matrix as happens in the case of CHC. Complementary studies of the photochemical stability of these matrices in solid state were also conducted. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Laser desorption/ionization techniques in the characterization of high-molecular-weight oil fractions,Part 2: de-asphalted oils

    Andrea Rizzi
    Abstract The composition of the de-asphalted oil fraction obtained from two different Italian fields was studied by laser desorption/ionization mass spectrometry. These fractions were treated with different solvent mixtures, and subfractions containing saturates, aromatic and polar compounds were obtained and analyzed by the same instrumental approach. The investigation showed clear differences between the samples coming from the two oils. The instrumental approach did not lead to an accurate description of the different components in terms of elemental composition and structures; however, valid information could be obtained on the molecular weight distribution of the components of the different fractions. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    An effective derivatization method for matrix-assisted laser desorption/ionization mass spectrometry of poly(acrylic acid)

    Ryuichi Arakawa

    Advanced glycation end products: a highly complex set of biologically relevant compounds detected by mass spectrometry,

    Annunziata Lapolla
    Abstract Structural information on ,AGE-peptides,' a class of substances belonging to advanced glycation end products (AGE) and originating by proteolysis of glycated proteins, was gained through various analytical approaches on the mixture produced by proteinase K digestion of in vitro glycated bovine serum albumin. Both matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and high-performance liquid chromatography/electrospray ionization mass spectrometry (HPLC/ESI-MS) were employed, and the results were compared with those from conventional spectroscopic methods (UV, fluorescence, gel permeation). The data acquired by the various techniques all depict the digestion mixtures as highly complex, with components exhibiting molecular mass in the range 300,3500 Da. In the analysis of HPLC/ESI-MS data, identification of AGE-peptides was facilitated by 3D mapping. Structural information was gained by means of multiple mass spectrometric experiments. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update covering the period 2001,2002

    David J. Harvey
    Abstract This review is the second update of the original review on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates that was published in 1999. It covers fundamental aspects of the technique as applied to carbohydrates, fragmentation of carbohydrates, studies of specific carbohydrate types such as those from plant cell walls and those attached to proteins and lipids, studies of glycosyl-transferases and glycosidases, and studies where MALDI has been used to monitor products of chemical synthesis. Use of the technique shows a steady annual increase at the expense of older techniques such as FAB. There is an increasing emphasis on its use for examination of biological systems rather than on studies of fundamental aspects and method development and this is reflected by much of the work on applications appearing in tabular form. © 2008 Wiley Periodicals, Inc., Mass Spec Rev 27:125,201, 2008 [source]

    Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update covering the period 1999,2000

    David J. Harvey
    Abstract This review describes the use of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry for the analysis of carbohydrates and glycoconjugates and continues coverage of the field from the previous review published in 1999 (D. J. Harvey, Matrix-assisted laser desorption/ionization mass spectrometry of carbohydrates, 1999, Mass Spectrom Rev, 18:349,451) for the period 1999,2000. As MALDI mass spectrometry is acquiring the status of a mature technique in this field, there has been a greater emphasis on applications rather than to method development as opposed to the previous review. The present review covers applications to plant-derived carbohydrates, N- and O- linked glycans from glycoproteins, glycated proteins, mucins, glycosaminoglycans, bacterial glycolipids, glycosphingolipids, glycoglycerolipids and related compounds, and glycosides. Applications of MALDI mass spectrometry to the study of enzymes acting on carbohydrates (glycosyltransferases and glycosidases) and to the synthesis of carbohydrates, are also covered. © 2006 Wiley Periodicals, Inc., Mass Spec Rev 25:595,662, 2006 [source]

    A strategy for high-resolution protein identification in surface-enhanced laser desorption/ionization mass spectrometry: Calgranulin A and chaperonin 10 as protein markers for endometrial carcinoma

    Jingzhong Guo
    Abstract Surface-enhanced laser desorption/ionization-mass spectrometry (SELDI-MS) has conventionally been practiced on linear time of flight (TOF) which has low mass accuracy and resolution. Here we demonstrate in an examination of both malignant and nonmalignant endometrial tissue homogenates that high mass accuracy and resolution in the MS stage are crucial. Using a commercially available quadrupole/TOF (QqTOF), we were able to resolve two potential cancer markers, subsequently identified off-line as chaperonin 10 and calgranulin A, that differ by 8 Da in mass. Two off-line protein identification protocols were developed: the first was based on size-exclusion chromatography (SEC), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), protein extraction, trypsin digestion, and matrix-assisted laser desorption/ionization-tandem MS (MALDI-MS/MS); the second on SEC and shotgun nano-liquid chromatography (nanoLC)-MS/MS. Analyses on a cohort of 44 endometrial homogenates showed 22 out of 23 nonmalignant samples had nondetectable to very low abundance of chaperonin 10 and calgranulin A; 17 of the 21 malignant samples had detectable to abundant levels of both proteins. Immunohistochemical staining of a tissue microarray of 32 samples showed that approximately half of malignant endometrial tissues exhibited positive staining for calgranulin A in the malignant epithelium, while 9 out of 10 benign tissues exhibited negative epithelial staining. In addition, macrophages/granulocytes in malignant as well as nonmalignant tissues showed positive staining. No immunostaining occurred in stroma or myometrium. Calgranulin A, in combination with chaperonin 10 and other proteins, may eventually constitute a panel of markers to permit diagnosis and screening of endometrial cancer. [source]

    Comparative proteome analysis of secretory proteins from pathogenic and nonpathogenic Listeria species

    Matthias Trost
    Abstract Extracellular proteins of bacterial pathogens play a crucial role in the infection of the host. Here we present the first comprehensive validation of the secretory subproteome of the Gram positive pathogen Listeria monocytogenes using predictive bioinformatic and experimental proteomic approaches. The previous original signal peptide (SP) prediction (Glaser et al., Science 2001, 294, 849,852) has been greatly improved by an in-depth analysis using seven different bioinformatic tools. Subsequent careful classification of the resulting data gives a probability dependent annotation of 121 putatively secreted proteins of which 45 are novel. Complementary proteomic analysis using both two-dimensional gel electrophoresis/matrix assisted laser desorption/ionization mass spectrometry and high performance liquid chromatography/electrospray ionization-mass spectrometry has identified 105,proteins in the culture supernatant of L.,monocytogenes. Among these, we were able to detect all the currently known virulence factors with an SP showing the importance of this subproteome and demonstrating the reliability of the techniques used. The comparison between the L.,monocytogenes wildtype and the nonpathogenic species Listeria innocua was performed to reveal proteins probably involved in pathogenicity and/or the adaptation to their respective lifestyles. In addition to the eight known virulence factors, all of which have no orthologous genes in L.,innocua, eight additional proteins have been identified that exhibit the typical key feature defining the known listerial virulence factors. Further significant differences between the two species are evident in the group of cell wall and secretory proteins that warrant further study. Our investigation clearly demonstrates that the major difference between the pathogenic and nonpathogenic species, noted in the comparative genome analysis, manifests itself strongest in the secretome. [source]

    Proteomic analysis of nuclear proteins from proliferative and differentiated human colonic intestinal epithelial cells

    Natacha Turck
    Abstract Self-renewing tissues such as the intestine contain progenitor proliferating cells which subsequently differentiate. Cell proliferation and differentiation involve gene regulation processes which take place in the nucleus. A human intestinal epithelial cell line model (Caco2/TC7) which reproduces these dynamic processes has been used to perform proteomic studies on nuclear proteins. Nuclei from Caco2/TC7 cells at proliferative and differentiated stages were purified by subcellular fractionation. After two-dimensional gel electrophoresis separation and ruthenium staining, 400 protein spots were detected by image analysis. Eighty-five spots corresponding to 60 different proteins were identified by matrix-assisted laser desorption/ionization mass spectrometry in nuclei from proliferative cells. Comparison of nuclear proteomes from proliferative or differentiated cells by differential display resulted in the identification of differentially expressed proteins such as nucleolin, hnRNP A2/B1 and hnRNP A1. By using Western blot analysis, we found that the expression and number of specific isoforms of these nuclear proteins decreased in differentiated cells. Immunocytochemistry experiments also showed that in proliferative cells nucleolin was distributed in nucleoli-like bodies. In contrast, hnRNPs A2/B1 and A1 were dispersed throughout the nucleus. This study of the nuclear proteome from intestinal epithelial cells represents the first step towards the establishment of a protein database which will be a valuable resource in future studies on the differential expression of nuclear proteins in response to physiological, pharmacological and pathological modulations. [source]

    Semi-online nanoflow liquid chromatography/matrix-assisted laser desorption ionization mass spectrometry of synthetic polymers using an octadecylsilyl-modified monolithic silica capillary column

    Takehiro Watanabe
    We have designed a semi-online liquid chromatography/matrix-assisted laser desorption/ionization mass spectrometry (LC/MALDI-MS) system to introduce eluent from a octadecylsilyl (ODS) group modified monolithic silica capillary chromatographic column directly onto a sample plate for MALDI-MS analysis. Our novel semi-online system is useful for rapidly and sensitively examining the performance of a monolithic capillary column. An additional advantage is the small elution volume of a monolithic capillary column, which allows delicate eluents, such as 1,1,1,3,3,3,-hexafluoroisopropyl alcohol (HFIP), to be used to achieve cost-effective analysis. Using the semi-online LC/MALDI-MS system, chromatographic separation of polymers by the monolithic column with different eluents was studied. Separation of poly(methyl methacrylate) and Nylon 6/6 showed that the column functioned via size-exclusion separation when tetrahydrofuran or HFIP eluent was used. On the other hand, the separation behavior of Nylon 11 indicated a reversed-phase mode owing to the interaction of the polymer with the modified ODS group in the column. Using tetrahydrofuran/methanol (1:1, v/v) as the eluent, the LC/MALDI-MS spectra of poly(lactic acid), which contains both linear and cyclic polymer structures, showed that the column could separate the hydrophobic cyclic polymer and elute it out relatively slowly. The monolithic column functions basically via size-exclusion separation; the reversed-phase separation by interaction with the ODS functions may have less influence on column separation. The semi-online monolithic capillary LC/MALDI-MS method we have developed should provide a means of effectively analyzing synthetic polymers. Copyright © 2010 John Wiley & Sons, Ltd. [source]

    Electrospray ionization and atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry of antioxidants applied in lubricants,

    Alexander Kassler
    The aim of this study was to investigate the utility of ion trap mass spectrometry (ITMS) in combination with the two desorption/ionization methods, electrospray (ESI) and atmospheric pressure matrix-assisted laser desorption/ionization (AP-MALDI), for the detection of antioxidants which are applied in lubricants. These experiments should form the base for future investigations of antioxidants in tribologically formed thin layers on the surface of frictional systems. Seventeen different antioxidants were selected out of the group of hindered phenolic and aromatic aminic compounds. Practically all antioxidants could be characterized by positive ion ESI- and AP-MALDI-ITMS, forming various types/species of molecular ions (e.g. [M]+., [M+H]+, [M+Na]+ or [M,2H+H]+). A few compounds could be analyzed by negative ion ESI-MS, too, but none by negative ion AP-MALDI-MS. The influence of target materials in AP-MALDI-MS (gold- and titanium nitride (TiN)-covered stainless steel, micro-diamond-covered hard metal, hand-polished and sand-blasted stainless steel targets) with respect to the molecular ion intensity and type of molecular ion of two selected antioxidants was evaluated. The surface properties are of particular interest because in friction tests different materials with different surface characteristics are used. However, the MS results indicate that optimal target surfaces have to be found for individual antioxidants in AP-MALDI-MS but in general smooth surfaces were superior to rough surfaces. Finally the gold-covered stainless steel MALDI target provided the best mass spectra and was selected for all the antioxidants investigated. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Selective photocatalytic degradation of poly(ethylene glycol) additives using TiO2 surface-assisted laser desorption/ionization mass spectrometry

    Takehiro Watanabe
    First page of article [source]

    Method development for direct detection of glycoproteins on aminophenylboronic acid functionalized self-assembled monolayers by matrix-assisted laser desorption/ionization mass spectrometry

    Kyung Kook Jang
    First page of article [source]

    The effect of sodium dodecyl sulfate and anion-exchange silica gel on matrix-assisted laser desorption/ionization mass spectrometric analysis of proteins

    Miwako Asanuma
    Sodium dodecyl sulfate (SDS), an anionic surfactant, is widely used in peptide and protein sample preparation. When the sample is analyzed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), this surfactant can often cause signal suppression. We have previously reported an on-probe sample preparation method using a suspension of anion-exchange silica gel and sinapinic acid (i.e., gel-SA suspension) as a matrix, thereby greatly improving the MALDI signal detection of the protein solutions containing SDS. In this study, we found that a certain amount of SDS enhanced the MALDI signal intensity for protein samples. This effect was also observed when using sodium decyl sulfate and sodium tetradecyl sulfate instead of SDS. Furthermore, this on-probe sample preparation method using both SDS and the gel-SA suspension improved the detection limit of protein samples in the MALDI-MS analysis by about ten-fold as compared to that of protein samples without SDS and the gel-SA suspension. This method can be applied not only to the MALDI-MS analysis of samples containing SDS, but also to the examination of proteins at femtomole levels or insoluble proteins such as membrane proteins. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Study of bisphosphonates by matrix-assisted laser desorption/ionization mass spectrometry , influence of alkali atoms on fragmentation patterns

    Erwann Guénin
    1-Hydroxymethylene-1,1-bisphosphonic acids (or bisphosphonates) are compounds that have interesting pharmacological applications. However, few mass spectrometric investigations have been carried out to determine their fragmentation patterns. Herein, we evaluated different matrices for the study by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) of the formation and fragmentation of the protonated, the cationized (MNa+ and MK+) and the deprotonated bisphosphonates. Some in-source fragmentations were observed both in positive and in negative ion modes. The fragmentation patterns obtained in post-source decay mode are also discussed. In contrast to previous electrospray ionization/multi-stage mass spectrometry (ESI-MSn) studies, some new fragmentation pathways were deduced and the effects of alkali ions on the fragmentation patterns were shown. The results summarized here completed the data previously recorded by ESI-MSn and could be used for the characterization of bisphosphonates as alkali complexes in biological mixtures. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Quantification of Greenland halibut serum vitellogenin: a trip from the deep sea to the mass spectrometer

    Alejandro M. Cohen
    This paper focuses on the sequential steps involved in developing a technique for quantifying Greenland halibut vitellogenin, a serum protein biomarker, using a comprehensive mass spectrometric approach. In the first phase of this study, in-gel trypsin digestions of serum proteins separated by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) were analyzed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). A characteristic band around a molecular mass of 185,kDa, present in the mature female specimens, but absent in the male samples, was identified as vitellognin according to the peptide mass fingerprint obtained by MALDI-MS. Subsequently, MALDI and electrospray ionization tandem mass spectrometry (ESI-MS/MS) analyses were performed on the digest of the vitellogenin band for de novo sequencing. From these studies, a characteristic 'signature' peptide (sequence: FFGQEIAFANIDK) was selected from a list of candidate peptides as a surrogate analytical standard used for quantification purposes. Sample preparation for vitellogenin quantification consisted of a simple one-step overnight trypsin digestion. Samples were spiked with an isotopologue signature peptide standard and analyzed by high-performance liquid chromatography (HPLC) coupled in-line to an electrospray quadrupole-hexapole-quadrupole tandem mass spectrometer, operated in selective reaction monitoring mode. Transitions [(m/z 750.0,,,1020.4 and 750.0,,,1205.4) and (754.8,,,1028.6 and 754.8,,,1213.2)] were monitored for the signature peptide and the internal standard, respectively. Samples obtained from the field showed that vitellogenin levels were in accordance with fish maturity determined by macroscopic examination of the gonad, proving this technique suitable for measuring vitellogenin as a serum protein biomarker for reproductive maturity in female fish. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Reverse micellar microextraction for rapid analysis of thiol-containing peptides and amino acids by atmospheric-pressure matrix-assisted laser desorption/ionization ion trap and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

    Kavita Agrawal
    Simple, rapid and inexpensive one-step reverse micellar microextraction (RMME) procedures were combined with matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) for the determination of thiol-containing peptides and amino acids. In this investigation, a thiol-containing peptide (HW6) was chosen as model compound to understand the mechanism of RMME. The electrostatic interactions between the thiol-containing peptide and reverse micelles were proposed to be reason for the transfer of analytes from the aqueous phase to the organic phase. Reverse micelles were formed by the cationic surfactant, methyltrioctylammonium chloride (MTOAC). The best extraction efficiency of HW6 was obtained under the following conditions: pH 11.0, ionic strength 5.0,mM of KCl and micelle concentration 7.0,mM of MTOAC. The limits of detection (LODs) obtained for HW6 in water, urine and plasma samples were 0.15, 0.19 and 0.28,µM, respectively, with relative standard deviation (RSD) values in the range ±8.8,10.5%. The sensitivity obtained in water by the present method was 45-fold higher than that of the conventional use of atmospheric-pressure (AP)-MALDI MS. Furthermore, the applicability of the proposed approach was extended for the determination of thiol-containing amino acids in sample solutions by using MALDI time-of-flight (TOF) MS. Copyright © 2008 John Wiley & Sons, Ltd. [source]