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Sample records for mass spectrometric mapping

  1. Mass spectrometric immunoassay

    DOEpatents

    Nelson, Randall W; Williams, Peter; Krone, Jennifer Reeve

    2013-07-16

    Rapid mass spectrometric immunoassay methods for detecting and/or quantifying antibody and antigen analytes utilizing affinity capture to isolate the analytes and internal reference species (for quantification) followed by mass spectrometric analysis of the isolated analyte/internal reference species. Quantification is obtained by normalizing and calibrating obtained mass spectrum against the mass spectrum obtained for an antibody/antigen of known concentration.

  2. Mass spectrometric immunoassay

    DOEpatents

    Nelson, Randall W.; Williams, Peter; Krone, Jennifer Reeve

    2005-12-13

    Rapid mass spectrometric immunoassay methods for detecting and/or quantifying antibody and antigen analytes utilizing affinity capture to isolate the analytes and internal reference species (for quantification) followed by mass spectrometric analysis of the isolated analyte/internal reference species. Quantification is obtained by normalizing and calibrating obtained mass spectrum against the mass spectrum obtained for an antibody/antigen of known concentration.

  3. Mass spectrometric immunoassay

    DOEpatents

    Nelson, Randall W; Williams, Peter; Krone, Jennifer Reeve

    2007-12-04

    Rapid mass spectrometric immunoassay methods for detecting and/or quantifying antibody and antigen analytes utilizing affinity capture to isolate the analytes and internal reference species (for quantification) followed by mass spectrometric analysis of the isolated analyte/internal reference species. Quantification is obtained by normalizing and calibrating obtained mass spectrum against the mass spectrum obtained for an antibody/antigen of known concentration.

  4. Mass spectrometric peptide mapping analysis and structural characterization of dihydrodiol dehydrogenase isoenzymes.

    PubMed Central

    Gauss, C; Klein, J; Post, K; Suckau, D; Schneider, K; Thomas, H; Oesch, F; Przybylski, M

    1990-01-01

    The direct molecular weight determination and structural analysis of polypeptides and peptide mixtures have become amenable by the recent development of fast atom bombardment (FABMS) and 252Cf-plasma desorption (PDMS) mass spectrometry. FABMS and PDMS peptide mapping, i.e., the direct analysis of peptide mixtures resulting from proteolytic digestion, have been developed as powerful methods for the structural characterization of epoxide-metabolizing isoenzymes. The major advantage of this approach is provided by the selectivity of the endoproteolytic cleavage, combined with the specific and accurate molecular weight determination of complex digest mixtures containing peptides up to several thousands daltons in size. Furthermore, the mass spectrometric peptide mapping analysis can be combined with a range of protein-chemical modification reactions and with sequential degradation such as by carboxypeptidases. Both FABMS and PDMS peptide mapping have already been successfully applied to the structural differentiation of glutathione transferase and epoxide hydrolase isoenzymes in cases where references sequence data for at least one isoenzyme form was available. In the application described here, for a series of dihydrodiol dehydrogenase (DDH) isoenzymes with hitherto undetermined primary structures, a direct correlation between the structural differentiation from peptide mapping data and differences in their substrate specificities could be demonstrated. The mass spectrometric peptide mapping analysis of isoenzymes proved to be an efficient basis for the elucidation of the structure of one major DDH isoenzyme form; partial sequence data for this protein are reported. PMID:2272334

  5. Mass Spectrometric Immunoassay Revisited

    PubMed Central

    Nelson, Randall W.; Borges, Chad R.

    2013-01-01

    The progressive understanding and improvement of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS), realized over the years through the considerable efforts of Dr. Marvin Vestal, have made possible numerous comparable efforts involving its application in the biological sciences. Here we revisit the concepts behind one such analytical approach, Mass Spectrometric Immunoassay, which is designed to selectively detect and quantify proteins present in biological milieu. PMID:21953037

  6. Mass spectrometric analysis of integral membrane proteins: application to complete mapping of bacteriorhodopsins and rhodopsin.

    PubMed Central

    Ball, L. E.; Oatis, J. E.; Dharmasiri, K.; Busman, M.; Wang, J.; Cowden, L. B.; Galijatovic, A.; Chen, N.; Crouch, R. K.; Knapp, D. R.

    1998-01-01

    Integral membrane proteins have not been readily amenable to the general methods developed for mass spectrometric (or internal Edman degradation) analysis of soluble proteins. We present here a sample preparation method and high performance liquid chromatography (HPLC) separation system which permits online HPLC-electrospray ionization mass spectrometry (ESI-MS) and -tandem mass spectrometry (MS/MS) analysis of cyanogen bromide cleavage fragments of integral membrane proteins. This method has been applied to wild type (WT) bacteriorhodopsin (bR), cysteine containing mutants of bR, and the prototypical G-protein coupled receptor, rhodopsin (Rh). In the described method, the protein is reduced and the cysteine residues pyridylethylated prior to separating the protein from the membrane. Following delipidation, the pyridylethylated protein is cleaved with cyanogen bromide. The cleavage fragments are separated by reversed phase HPLC using an isopropanol/acetonitrile/aqueous TFA solvent system and the effluent peptides analyzed online with a Finnigan LCQ Ion Trap Mass Spectrometer. With the exception of single amino acid fragments and the glycosylated fragment of Rh, which is observable by matrix assisted laser desorption ionization (MALDI)-MS, this system permits analysis of the entire protein in a single HPLC run. This methodology will enable pursuit of chemical modification and crosslinking studies designed to probe the three dimensional structures and functional conformational changes in these proteins. The approach should also be generally applicable to analysis of other integral membrane proteins. PMID:9541408

  7. Constraining geochemistry and biological primary productivity in hydrothermal systems via in situ mass spectrometric geochemical mapping

    NASA Astrophysics Data System (ADS)

    Vidoudez, Charles; Marcon, Yann; Bach, Wolfgang; Lebris, Nadine; Dubilier, Nicole; Girguis, Peter

    2014-05-01

    Hydrothermal vent ecosystems are biological hot spots, supported by chemoautotrophic primary productivity and achieving densities comparable to rainforests. Nevertheless, our understanding of the geochemical factors that govern the distribution of animals and microbes within vents is limited. It is well known that vent endemic organisms are found in specific vent "microenvironments", and that these microenvironments are distributed -coarsely speaking- in predictable patterns within a vent field. However, the relative differences in activity among these faunal patches, and their role in influencing geochemical flux remains largely unknown due to historical limitations in our ability to sample and quantify geochemical constituents with fine spatial resolution. In particular, the distribution of biologically important volatiles around vent fields is poorly constrained, as is the degree to which their distribution influences the destiny and distribution of organisms. To characterize the relationship between the distribution of volatiles, chemosynthetic microbes, and chemosynthetic symbioses, we generated detailed geo-referenced maps of methane, hydrogen sulfide, carbon dioxide and oxygen (four of the key volatiles that are both vent- and seawater derived) using an in situ mass spectrometer (ISMS). We characterized these concentrations in over 130 spots across three vent sites associated with the mid-Atlantic ridge in the Menez Gwen vent field. We quantified gases in sites ranging from hot fluids to mussel beds, and found notable relationships between the distribution and consumption of hydrogen sulfide and methane and the animal and microbial communities. Finally, we also developed a metabolic energy "map", which enables us to constrain both the potential energy that is available to these communities as well as the extent to which it is being used, and places constraints on the extent of primary production that can be supported by the realized use of these volatiles.

  8. In-depth mass spectrometric mapping of the human vitreous proteome

    PubMed Central

    2013-01-01

    Mapping of proteins involved in normal eye functions is a prerequisite to identify pathological changes during eye disease processes. We therefore analysed the proteome of human vitreous by applying in-depth proteomic screening technologies. For ethical reasons human vitreous samples were obtained by vitrectomy from “surrogate normal patients” with epiretinal gliosis that is considered to constitute only negligible pathological vitreoretinal changes. We applied different protein prefractionation strategies including liquid phase isoelectric focussing, 1D SDS gel electrophoresis and a combination of both and compared the number of identified proteins obtained by the respective method. Liquid phase isoelectric focussing followed by SDS gel electrophoresis increased the number of identified proteins by a factor of five compared to the analysis of crude unseparated human vitreous. Depending on the prefractionation method proteins were subjected to trypsin digestion either in-gel or in solution and the resulting peptides were analysed on a UPLC system coupled online to an LTQ Orbitrap XL mass spectrometer. The obtained mass spectra were searched against the SwissProt database using the Mascot search engine. Bioinformatics tools were used to annotate known biological functions to the detected proteins. Following this strategy we examined the vitreous proteomes of three individuals and identified 1111 unique proteins. Besides structural, transport and binding proteins, we detected 261 proteins with known enzymatic activity, 51 proteases, 35 protease inhibitors, 35 members of complement and coagulation cascades, 15 peptide hormones, 5 growth factors, 11 cytokines, 47 receptors, 30 proteins of visual perception, 91 proteins involved in apoptosis regulation and 265 proteins with signalling activity. This highly complex mixture strikingly differs from the human plasma proteome. Thus human vitreous fluid seems to be a unique body fluid. 262 unique proteins were detected

  9. Mass spectrometric immunoassay

    SciTech Connect

    Nelson, R.W.; Krone, J.R.; Bieber, A.L.; Williams, P.

    1995-04-01

    A new, general method of immunoassay is demonstrated. The approach is based on the microscale immunoaffinity capture of target antigens followed by mass-specific identification and quantitation using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Immunoaffinity capture of antigens effectively overcomes signal suppression effects typically encountered during traditional matrix-assisted laser desorption/ionization analysis of complex biological mixtures while simultaneously concentrating the analyte into a small volume. Sample incubation and processing methods were such that a typical analysis could be performed in less than 1 h while subnanomolar sensitivities were maintained. The technique has been used for the rapid, selective, and quantitative screening of human blood for the presence of myotoxin a, and Mojave toxin from the venoms of the prairie rattlesnake, Crotalus virdis virdis, and the Mojave rattlesnake, Crotalus scutulatus scutulatus. 18 refs., 8 figs.

  10. Mass Spectrometric Studies of Oxides

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.

    2012-01-01

    Current studies at NASA Glenn on oxide thermodynamics are discussed. Previous studies on the vaporization of B2O3 in reducing atmospheres led to inconsistent studies when B was used as a reductant. It is shown that liquid B2O3 does not wet B and a clear phase separation was noted in the Knudsen cell. This problem was solved by using FeB and Fe2B to supply a different and constant activity of B. The thermodynamic data thus derived are compared to quantum chemical composite calculations. A major problem in high temperature mass spectrometry is the determination of accurate ionization cross sections, particularly for molecules. The method of Deutsch and Mark shows promise and some sample calculations are discussed. Finally current studies on the thermodynamics of rare earth silicates are discussed. Here the problems are obtaining a measurable signal from SiO2 vaporization and non-equilibrium vaporization. The use of a Ta reducing agent provides a stronger signal, which is related to silica activity. The Whitman-Motzfeld relation adapted to KEMS measurements is applied to obtain equilibrium pressures.

  11. Challenges and recent advances in mass spectrometric imaging of neurotransmitters

    PubMed Central

    Gemperline, Erin; Chen, Bingming; Li, Lingjun

    2014-01-01

    Mass spectrometric imaging (MSI) is a powerful tool that grants the ability to investigate a broad mass range of molecules, from small molecules to large proteins, by creating detailed distribution maps of selected compounds. To date, MSI has demonstrated its versatility in the study of neurotransmitters and neuropeptides of different classes toward investigation of neurobiological functions and diseases. These studies have provided significant insight in neurobiology over the years and current technical advances are facilitating further improvements in this field. neurotransmitters, focusing specifically on the challenges and recent Herein, we advances of MSI of neurotransmitters. PMID:24568355

  12. Electrospray Modifications for Advancing Mass Spectrometric Analysis

    PubMed Central

    Meher, Anil Kumar; Chen, Yu-Chie

    2017-01-01

    Generation of analyte ions in gas phase is a primary requirement for mass spectrometric analysis. One of the ionization techniques that can be used to generate gas phase ions is electrospray ionization (ESI). ESI is a soft ionization method that can be used to analyze analytes ranging from small organics to large biomolecules. Numerous ionization techniques derived from ESI have been reported in the past two decades. These ion sources are aimed to achieve simplicity and ease of operation. Many of these ionization methods allow the flexibility for elimination or minimization of sample preparation steps prior to mass spectrometric analysis. Such ion sources have opened up new possibilities for taking scientific challenges, which might be limited by the conventional ESI technique. Thus, the number of ESI variants continues to increase. This review provides an overview of ionization techniques based on the use of electrospray reported in recent years. Also, a brief discussion on the instrumentation, underlying processes, and selected applications is also presented. PMID:28573082

  13. Enzyme linked immuno mass spectrometric assay (ELIMSA).

    PubMed

    Florentinus-Mefailoski, Angelique; Safi, Frozan; Marshall, John G

    2014-01-16

    biological samples, industrial products or the environment may be detected by probes that bind to the target analyte. Combining the reporter enzymes from ELISA with sensitive liquid chromatography (LC), electrospray ionization (ESI) and tandem mass spectrometry (MS/MS) will permit the sensitive detection and quantification of the molecular probes by Enzyme Linked Immuno Mass Spectrometric Assay (ELIMSA). The flexibility and sensitivity of mass spectrometry to measure large numbers of compounds simultaneously should permit the quantification of multiple ELIMSA reactions at separate mass-to-charge (m/z) ratios. Hence ELIMSA and it variants should permit the rapid and simple detection and quantification of many molecules over the complete range of biologically important concentrations without the use of radiolabels using only existing antibodies, reagents and instruments. Antibodies coupled to reporter enzymes that are widely used in biomedical and environmental applications can now be detected and quantified using ultra sensitive mass spectrometry to create a sensitive and flexible ELIMSA system. Absolute standards of analytes or enzyme product may serve as a reference. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Mass Spectrometric Immunoassays in Characterization of Clinically Significant Proteoforms

    PubMed Central

    Trenchevska, Olgica; Nelson, Randall W.; Nedelkov, Dobrin

    2016-01-01

    Proteins can exist as multiple proteoforms in vivo, as a result of alternative splicing and single-nucleotide polymorphisms (SNPs), as well as posttranslational processing. To address their clinical significance in a context of diagnostic information, proteoforms require a more in-depth analysis. Mass spectrometric immunoassays (MSIA) have been devised for studying structural diversity in human proteins. MSIA enables protein profiling in a simple and high-throughput manner, by combining the selectivity of targeted immunoassays, with the specificity of mass spectrometric detection. MSIA has been used for qualitative and quantitative analysis of single and multiple proteoforms, distinguishing between normal fluctuations and changes related to clinical conditions. This mini review offers an overview of the development and application of mass spectrometric immunoassays for clinical and population proteomics studies. Provided are examples of some recent developments, and also discussed are the trends and challenges in mass spectrometry-based immunoassays for the next-phase of clinical applications. PMID:28248223

  15. Characterization of a discontinuous epitope of the human immunodeficiency virus (HIV) core protein p24 by epitope excision and differential chemical modification followed by mass spectrometric peptide mapping analysis.

    PubMed

    Hochleitner, E O; Borchers, C; Parker, C; Bienstock, R J; Tomer, K B

    2000-03-01

    A combination of epitope excision, epitope extraction, and differential chemical modification followed by mass spectrometric peptide mapping was used for the characterization of a discontinuous epitope that is recognized by the mouse anti-HIV-p24 monoclonal antibody 5E2.A3. In epitope excision, the protein is first bound to an immobilized antibody and then digested with proteolytic enzymes. In epitope extraction, the protein is first digested and subsequently allowed to react with the antibody. After epitope excision of the p24-5E2.A3 complex with endoproteinase Lys-C, a large fragment remained affinity bound corresponding to amino acids 1-158 of HIV-p24 (fragment 1-158). Further digestion, however, resulted in loss of affinity. Moreover, no affinity-bound fragments were observed after an epitope extraction experiment. These data from the epitope excision and extraction experiments suggest that the epitope is discontinuous. For the further characterization of the epitope, amino groups in the epitope-containing fragment were acetylated in both the affinity bound and free states followed by mass spectrometric analysis. Two successive acetylation reactions were performed: (1) the first used a low molar excess of acetic anhydride, and (2) the second, after separation from the antibody, a high molar excess of its hexadeuteroderivative. This isotopic labeling procedure, in combination with high resolution mass spectrometry, allowed the precise determination of relative reactivities of amino groups. In this study, no differences were observed in the ranking of the relative reactivities of five lysine residues. However, the N-terminal amino group was found to be part of the discontinuous epitope.

  16. Characterization of a discontinuous epitope of the human immunodeficiency virus (HIV) core protein p24 by epitope excision and differential chemical modification followed by mass spectrometric peptide mapping analysis.

    PubMed Central

    Hochleitner, E. O.; Borchers, C.; Parker, C.; Bienstock, R. J.; Tomer, K. B.

    2000-01-01

    A combination of epitope excision, epitope extraction, and differential chemical modification followed by mass spectrometric peptide mapping was used for the characterization of a discontinuous epitope that is recognized by the mouse anti-HIV-p24 monoclonal antibody 5E2.A3. In epitope excision, the protein is first bound to an immobilized antibody and then digested with proteolytic enzymes. In epitope extraction, the protein is first digested and subsequently allowed to react with the antibody. After epitope excision of the p24-5E2.A3 complex with endoproteinase Lys-C, a large fragment remained affinity bound corresponding to amino acids 1-158 of HIV-p24 (fragment 1-158). Further digestion, however, resulted in loss of affinity. Moreover, no affinity-bound fragments were observed after an epitope extraction experiment. These data from the epitope excision and extraction experiments suggest that the epitope is discontinuous. For the further characterization of the epitope, amino groups in the epitope-containing fragment were acetylated in both the affinity bound and free states followed by mass spectrometric analysis. Two successive acetylation reactions were performed: (1) the first used a low molar excess of acetic anhydride, and (2) the second, after separation from the antibody, a high molar excess of its hexadeuteroderivative. This isotopic labeling procedure, in combination with high resolution mass spectrometry, allowed the precise determination of relative reactivities of amino groups. In this study, no differences were observed in the ranking of the relative reactivities of five lysine residues. However, the N-terminal amino group was found to be part of the discontinuous epitope. PMID:10752610

  17. Mass spectrometric detection, identification, and fragmentation of arseno-phytochelatins.

    PubMed

    Schmied-Tobies, Maria I H; Arroyo-Abad, Uriel; Mattusch, Jürgen; Reemtsma, Thorsten

    2014-11-01

    Phytochelatins (PC) are cystein-rich oligopeptides in plants for coordination with toxic metals and metalloids via their thiol groups. The composition, structure, and mass spectrometric fragmentation of arseno-PC (As-PC) with PC of different degree of oligomerization (PC2-PC5) in solution were studied using liquid chromatography coupled in parallel to inductively coupled plasma mass spectrometry and electrospray ionization quadrupole time-of-flight mass spectrometry. As-PC were detected from As(PC2) to As(PC5) with an increasing number of isomers that differ in the position of thiol groups bound to As. Thermodynamic modeling supported the identification process in case of these isomers. Mass spectrometric fragmentation of the As-PC does not follow the established pattern of peptides but is governed by the formation of series of As-containing annular cations, which coordinate to As via S, N, or O. Structure proposals for 30 As-PC fragment ions in the range m/z 147.92 to m/z 1290.18 are elaborated. Many of these fragment ions are characteristic to several As-PC and may be suited for a screening for As-PC in plant extracts. The mass spectrometric data offer the perspective for a future more sensitive determination of As-PC by means of liquid chromatography tandem mass spectrometry with multiple reaction monitoring. Copyright © 2014 John Wiley & Sons, Ltd.

  18. A NEW MASS SPECTROMETRIC TECHNIQUE FOR ...

    EPA Pesticide Factsheets

    Most organic compounds are not found in mass spectral libraries and cannot be easily identified from low resolution mass spectra. Ion Composition Elucidation (ICE) utilizes selected ion recording with a double focusing mass spectrometer in a new way to determine exact masses and relative abundances of ions more rapidly and with greater accuracy than by full scanning. These measurements are made as analytes from a complex mixture elute from a GC column into the ion source. The exact masses and relative abundances establish the elemental compositions of the ions in a mass spectrum, which limits the possible identify of the compound sufficiently to make searches of the chemical and commercial literature feasible. ICE has two facets: Mass Peak Profiling from Selected Ion Recording Data (MPPSIRD) for data acquisition and a Profile Generation Model (PGM) for automated data interpretation. NTPSIRD and the PGM will be described and several applications of ICE will be shown: tentative identification of a compound that provided a mass spectrum with I I plausible NIST library matches; confirmation of the presence of temazepam, a sedative and one of the 200 most prescribed drugs in 1999. The research focused on in the subtasks is the development and application of state-of the-art technologies to meet the needs of the public, Office of Water, and ORD in the area of Water Quality. Located In the subtasks are the various research projects being performed in support of this T

  19. Mass-spectrometric measurements for nuclear safeguards

    SciTech Connect

    Carter, J.A.; Smith, D.H.; Walker, R.L.

    1982-01-01

    The need of an on-site inspection device to provide isotopic ratio measurements led to the development of a quadrupole mass spectrometer mounted in a van. This mobile laboratory has the ability, through the use of the resin bead technique, to acquire, prepare, and analyze samples of interest to nuclear safeguards. Precision of the measurements is about 1 to 2%.

  20. Mass Spectrometric Analysis of Histone Proteoforms

    NASA Astrophysics Data System (ADS)

    Yuan, Zuo-Fei; Arnaudo, Anna M.; Garcia, Benjamin A.

    2014-06-01

    Histones play important roles in chromatin, in the forms of various posttranslational modifications (PTMs) and sequence variants, which are called histone proteoforms. Investigating modifications and variants is an ongoing challenge. Previous methods are based on antibodies, and because they usually detect only one modification at a time, they are not suitable for studying the various combinations of modifications on histones. Fortunately, mass spectrometry (MS) has emerged as a high-throughput technology for histone analysis and does not require prior knowledge about any modifications. From the data generated by mass spectrometers, both identification and quantification of modifications, as well as variants, can be obtained easily. On the basis of this information, the functions of histones in various cellular contexts can be revealed. Therefore, MS continues to play an important role in the study of histone proteoforms. In this review, we discuss the analysis strategies of MS, their applications on histones, and some key remaining challenges.

  1. Electrospray tandem mass spectrometric investigations of morphinans.

    PubMed

    Raith, Klaus; Neubert, Reinhard; Poeaknapo, Chotima; Boettcher, Christian; Zenk, Meinhart H; Schmidt, Jürgen

    2003-11-01

    In this study positive ESI tandem mass spectra of the [M + H]+ ions of morphinan alkaloids obtained using an ion trap MS were compared with those from a triple quadrupole MS. This allows to assess the differences of the tandem-in-time versus the tandem-in-space principle, often hampering the development of ESI MS/MS libraries. Fragmentation pathways and possible fragment ion structures were discussed. In order to obtain elemental composition, accurate mass measurements were performed. According to the MS/MS fragmentation pathway, the investigated compounds can be grouped into 4 subsets: (1) morphine and codeine, (2) morphinone, codeinone, and neopinone, (3) thebaine and oripavine, (4) salutaridine and salutaridinol. Salutaridinol-7-O-acetate shows a different fragmentation behavior because of the favored loss of acetic acid. Although most fragment ions occur in both ion trap and triple quad tandem mass spectra, some are exclusively seen in either type. For triple quad, quadrupole time-of-flight and FT-ICR MS/MS, the base peak of morphine results from an ion at m/z 165 that contains neither nitrogen nor oxygen. This ion is not found in ion trap MS/MS, but in subsequential MS3 and MS4.

  2. Mass spectrometric measurement of thermospheric wind

    NASA Technical Reports Server (NTRS)

    Knutson, J. R.; Kayser, D. C.; Potter, W. E.

    1977-01-01

    The open source neutral mass spectrometer (OSS) on the Atmosphere Explorer C satellite was periodically operated in an experimental 'fly-through' mode. When the satellite is spinning, the signal from this mode displays a sharp maximum that occurs when the instrument source faces directly into the oncoming gas. Thus the location of this maximum is sensitive to neutral wind components in the spin plane. Twenty-two spinning fly-through orbits were analyzed to determine vertical wind magnitudes in the altitude range 160-250 km. Large (up to 65 m/s) magnitudes were detected in the early morning sector of the auroral zone.

  3. Chemical cross-linking with thiol-cleavable reagents combined with differential mass spectrometric peptide mapping--a novel approach to assess intermolecular protein contacts.

    PubMed Central

    Bennett, K. L.; Kussmann, M.; Björk, P.; Godzwon, M.; Mikkelsen, M.; Sørensen, P.; Roepstorff, P.

    2000-01-01

    The intermolecular contact regions between monomers of the homodimeric DNA binding protein ParR and the interaction between the glycoproteins CD28 and CD80 were investigated using a strategy that combined chemical cross-linking with differential MALDI-MS analyses. ParR dimers were modified in vitro with the thiol-cleavable cross-linker 3,3'-dithio-bis(succinimidylproprionate) (DTSSP), proteolytically digested with trypsin and analyzed by MALDI-MS peptide mapping. Comparison of the peptide maps obtained from digested cross-linked ParR dimers in the presence and absence of a thiol reagent strongly supported a "head-to-tail" arrangement of the monomers in the dimeric complex. Glycoprotein fusion constructs CD28-IgG and CD80-Fab were cross-linked in vitro by DTSSP, characterized by nonreducing SDS-PAGE, digested in situ with trypsin and analyzed by MALDI-MS peptide mapping (+/- thiol reagent). The data revealed the presence of an intermolecular cross-link between the receptor regions of the glycoprotein constructs, as well as a number of unexpected but nonetheless specific interactions between the fusion domains of CD28-IgG and the receptor domain of CD80-Fab. The strategy of chemical cross-linking combined with differential MALDI-MS peptide mapping (+ thiol reagent) enabled localization of the interface region(s) of the complexes studied and clearly demonstrates the utility of such an approach to obtain structural information on interacting noncovalent complexes. PMID:10975572

  4. Mass spectrometric thermodynamic studies of oxide systems and materials

    NASA Astrophysics Data System (ADS)

    Stolyarova, V. L.

    2016-01-01

    Progress in methods of synthesis of advanced materials as well as utilization of such materials at high temperatures requires information on the vaporization processes and thermodynamic properties of oxide systems. The optimal experimental method for these purposes is high-temperature mass spectrometry. This review summarizes and classifies experimental results obtained in mass spectrometric studies of the high-temperature thermodynamic properties of oxide systems and materials carried out in the last two decades. Published data on the vaporization processes and thermodynamic properties of oxide materials for high-temperature technologies are discussed from the standpoint of acid-base concept and model approaches including statistical thermodynamic methods. The bibliography includes 248 references.

  5. Outlier Detection for Mass Spectrometric Data.

    PubMed

    Cho, HyungJun; Eo, Soo-Heang

    2016-01-01

    Mass spectrometry data are often generated from various biological or chemical experiments. However, due to technical reasons, outlying observations are often obtained, some of which may be extreme. Identifying the causes of outlying observations is important in the analysis of replicated MS data because elaborate pre-processing is essential in order to obtain successful analyses with reliable results, and because manual outlier detection is a time-consuming pre-processing step. It is natural to measure the variability of observations using standard deviation or interquartile range calculations, and in this work, these criteria for identifying outliers are presented. However, the low replicability and the heterogeneity of variability are often obstacles to outlier detection. Therefore, quantile regression methods for identifying outliers with low replication are also presented. The procedures are illustrated with artificial and real examples, while a software program is introduced to demonstrate how to apply these procedures in the R environment system.

  6. Mass spectrometric studies of trimethylindium pyrolysis

    NASA Technical Reports Server (NTRS)

    Buchan, N. I.; Larsen, C. A.; Stringfellow, G. B.

    1988-01-01

    The kinetics of the pyrolysis of trimethylindium (TMIn) in He, D2, and H2 carriers was investigated using the atmospheric pressure flow-tube apparatus described by Larsen et al. (1987) and a time-of-flight mass spectrometer. The rate constant for the pyrolysis of TMIn in He was found to be comparable to that found by Jacko and Price (1964) for TMIn in toluene carrier (a radical scavenger), indicating that TMIn decomposes in He not by radical attack of methyl groups, but by homolytic fission. The decomposition of TMIn is enhanced in D2 and H2 carriers, where the principal products are CH3D and C2H6, and CH4 and C2H6, respectively, indicating that the reaction pathway in these carriers is different from those in He and toluene. The pyrolysis in H2 and D2 is attributed to a radical attack by H or D on TMIn. A reaction mechanism involving a short-lived hypervalent DTMIn species was proposed and was tested using numerical modeling techniques.

  7. Mass Spectrometric Discrimination of Squalene Monohydroperoxide Isomers.

    PubMed

    Shimizu, Naoki; Bersabe, Hannah; Ito, Junya; Kato, Shunji; Towada, Ryo; Eitsuka, Takahiro; Kuwahara, Shigefumi; Miyazawa, Teruo; Nakagawa, Kiyotaka

    2017-03-01

    Squalene (SQ), a main component of human sebum, is readily photooxidized by exposure to sunlight, producing six squalene monohydroperoxide (SQ-OOH) isomers. Despite its known connection to various skin conditions, few studies have sought to analyze SQ-OOH at the isomeric level. In this study, we aimed to develop a method to discriminate each SQ-OOH isomer with the use of tandem mass spectrometry (MS/MS). The six standard SQ-OOH isomers were prepared by photooxidizing SQ in the presence of rose bengal, a photosensitizer, and isolated by semipreparative high-performance liquid chromatography (HPLC). To purify each isomer, 2-methoxypropene, which reversibly reacts with the hydroperoxide group of SQ-OOH, was utilized. Product ion scanning was then performed on the standard SQ-OOH isomers in the absence and presence of the sodium ion. In the absence of the sodium ion, the fragmentation patterns produced by atmospheric pressure chemical ionization were similar between the isomers, whereas in the presence of the sodium ion by electrospray ionization, unique fragmentation patterns were achieved. Based on these fragment ions, HPLC-MS/MS multiple reaction monitoring analysis was conducted on a mixture of the standard SQ-OOH isomers. We achieved discrimination of SQ-OOH isomers with high selectivity and detected SQ-OOH isomers at nanogram levels. These results may improve our understanding of the effect of SQ-OOH on skin conditions as well as the mechanism behind SQ peroxidation.

  8. Hardware acceleration of processing of mass spectrometric data for proteomics.

    PubMed

    Bogdan, Istvan; Coca, Daniel; Rivers, Jenny; Beynon, Robert J

    2007-03-15

    High-resolution mass spectrometers generate large data files that are complex, noisy and require extensive processing to extract the optimal data from raw spectra. This processing is readily achieved in software and is often embedded in manufacturers' instrument control and data processing environments. However, the speed of this data processing is such that it is usually performed off-line, post data acquisition. We have been exploring strategies that would allow real-time advanced processing of mass spectrometric data, making use of the reconfigurable computing paradigm, which exploits the flexibility and versatility of Field Programmable Gate Arrays (FPGAs). This approach has emerged as a powerful solution for speeding up time-critical algorithms. We describe here a reconfigurable computing solution for processing raw mass spectrometric data generated by MALDI-ToF instruments. The hardware-implemented algorithms for de-noising, baseline correction, peak identification and deisotoping, running on a Xilinx Virtex 2 FPGA at 180 MHz, generate a mass fingerprint over 100 times faster than an equivalent algorithm written in C, running on a Dual 3 GHz Xeon workstation.

  9. Mass-spectrometric monitoring of the stress reaction during anesthesia

    NASA Astrophysics Data System (ADS)

    Elizarov, A. Yu.; Levshankov, A. I.; Faizov, I. I.; Shchegolev, A. V.

    2013-10-01

    Clinical testing data for a mass-spectrometric method of estimating the patient's stress reaction to an injury done during anesthesia are presented. The essence of the method is monitoring the respiratory coefficient, which is defined as ratio N of the expiratory mass concentration of CO2 to the inspiratory mass concentration of O2 at each breathing cycle. For on-line monitoring of N, an electron ionization mass spectrometer connected to the breathing circuit of an inhalational anesthesia machine is used. Estimates of the anesthesia adequacy obtained with this method are compared with those obtained with the method that analyzes induced acoustic encephalographic potentials. It is shown that the method suggested is more sensitive to the level of the patient's stress reaction during anesthesia than the induced potential method.

  10. A high pressure modulated molecular beam mass spectrometric sampling system

    NASA Technical Reports Server (NTRS)

    Stearns, C. A.; Kohl, F. J.; Fryburg, G. C.; Miller, R. A.

    1977-01-01

    The current state of understanding of free-jet high pressure sampling is critically reviewed and modifications of certain theoretical and empirical considerations are presented. A high pressure, free-jet expansion, modulated molecular beam, mass spectrometric sampling apparatus was constructed and this apparatus is described in detail. Experimental studies have demonstrated that the apparatus can be used to sample high temperature systems at pressures up to one atmosphere. Condensible high temperature gaseous species have been routinely sampled and the mass spectrometric detector has provided direct identification of sampled species. System sensitivity is better than one tenth of a part per million. Experimental results obtained with argon and nitrogen beams are presented and compared to theoretical predictions. These results and the respective comparison are taken to indicate acceptable performance of the sampling apparatus. Results are also given for two groups of experiments related to hot corrosion studies. The formation of gaseous sodium sulfate in doped methane-oxygen flames was characterized and the oxidative vaporization of metals was studied in an atmospheric pressure flowing gas system to which gaseous salt partial pressures were added.

  11. Mass spectrometric determination of early and advanced glycation in biology.

    PubMed

    Rabbani, Naila; Ashour, Amal; Thornalley, Paul J

    2016-08-01

    Protein glycation in biological systems occurs predominantly on lysine, arginine and N-terminal residues of proteins. Major quantitative glycation adducts are found at mean extents of modification of 1-5 mol percent of proteins. These are glucose-derived fructosamine on lysine and N-terminal residues of proteins, methylglyoxal-derived hydroimidazolone on arginine residues and N(ε)-carboxymethyl-lysine residues mainly formed by the oxidative degradation of fructosamine. Total glycation adducts of different types are quantified by stable isotopic dilution analysis liquid chromatography-tandem mass spectrometry (LC-MS/MS) in multiple reaction monitoring mode. Metabolism of glycated proteins is followed by LC-MS/MS of glycation free adducts as minor components of the amino acid metabolome. Glycated proteins and sites of modification within them - amino acid residues modified by the glycating agent moiety - are identified and quantified by label-free and stable isotope labelling with amino acids in cell culture (SILAC) high resolution mass spectrometry. Sites of glycation by glucose and methylglyoxal in selected proteins are listed. Key issues in applying proteomics techniques to analysis of glycated proteins are: (i) avoiding compromise of analysis by formation, loss and relocation of glycation adducts in pre-analytic processing; (ii) specificity of immunoaffinity enrichment procedures, (iii) maximizing protein sequence coverage in mass spectrometric analysis for detection of glycation sites, and (iv) development of bioinformatics tools for prediction of protein glycation sites. Protein glycation studies have important applications in biology, ageing and translational medicine - particularly on studies of obesity, diabetes, cardiovascular disease, renal failure, neurological disorders and cancer. Mass spectrometric analysis of glycated proteins has yet to find widespread use clinically. Future use in health screening, disease diagnosis and therapeutic monitoring, and

  12. Advances in Mass Spectrometric Tools for Probing Neuropeptides

    NASA Astrophysics Data System (ADS)

    Buchberger, Amanda; Yu, Qing; Li, Lingjun

    2015-07-01

    Neuropeptides are important mediators in the functionality of the brain and other neurological organs. Because neuropeptides exist in a wide range of concentrations, appropriate characterization methods are needed to provide dynamic, chemical, and spatial information. Mass spectrometry and compatible tools have been a popular choice in analyzing neuropeptides. There have been several advances and challenges, both of which are the focus of this review. Discussions range from sample collection to bioinformatic tools, although avenues such as quantitation and imaging are included. Further development of the presented methods for neuropeptidomic mass spectrometric analysis is inevitable, which will lead to a further understanding of the complex interplay of neuropeptides and other signaling molecules in the nervous system.

  13. Mass spectrometric profiling of flavonoid glycoconjugates possessing isomeric aglycones.

    PubMed

    Abrankó, László; Szilvássy, Blanka

    2015-01-01

    In fields such as food and nutrition science or plant physiology, interest in untargeted profiling of flavonoids continues to expand. The group of flavonoids encompasses several thousands of chemically distinguishable compounds, among which are a number of isobaric compounds with the same elemental composition. Thus, the mass spectrometric identification of these compounds is challenging, especially when reference standards are not available to support their identification. Many different types of isomers of flavonoid glycoconjugates are known, i.e. compounds that differ in their glycosylation position, glycan sequence or type of interglycosidic linkage. This work focuses on the mass spectrometric identification of flavonoid glycoconjugate isomers possessing the same glycan mass and differing only in their aglycone core. A non-targeted HPLC-ESI-MS/MS profiling method using a triple quadrupole MS is presented herein, which utilizes in-source fragmentation and a pseudo-MS(3) approach for the selective analysis of flavonoid glycoconjugates with isomeric/isobaric aglycones. A selective MRM-based identification of the in-source formed isobaric aglycone fragments was established. Additionally, utilizing the precursor scanning capability of the employed triple quadrupole instrument, the developed method enabled the determination of the molecular weight of the studied intact flavonoid glycoconjugate. The versatility of the method was proven with various types of flavonoid aglycones, i.e. anthocyanins, flavonols, flavones, flavanones and isoflavones, along with their representative glycoconjugates. The developed method was also successfully applied to a commercially available sour cherry sample, in which 16 different glycoconjugates of pelargonidin, genistein, cyanidin, kaempferol and quercetin could be tentatively identified, including a number of compounds containing isomeric/isobaric aglycones.

  14. Qualitative analysis of algal secretions with multiple mass spectrometric platforms.

    PubMed

    Kind, Tobias; Meissen, John K; Yang, Dawei; Nocito, Fernando; Vaniya, Arpana; Cheng, Yu-Shen; Vandergheynst, Jean S; Fiehn, Oliver

    2012-06-29

    Lipid secretions from algae pose a great opportunity for engineering biofueler feedstocks. The lipid exudates could be interesting from a process engineering perspective because lipids could be collected directly from the medium without harvesting and disrupting cells. We here report on the extracellular secretions of algal metabolites from the strain UTEX 2341 (Chlorella minutissima) into the culture medium. No detailed analysis of these lipid secretions has been performed to date. Using multiple mass spectrometric platforms, we observed around 1000 compounds and were able to annotate 50 lipids by means of liquid chromatography coupled to accurate mass quadrupole time-of-flight mass spectrometry (LC-QTOF), direct infusion with positive and negative electrospray ion trap mass spectrometry and gas chromatography coupled to mass spectrometry (GC-MS). These compounds were annotated by tandem mass spectral (MS/MS) database matching and retention time range filtering. We observed a series of triacylglycerols (TG), sulfoquinovosyldiacylglycerols (SQDG), phosphatidylinositols and phosphatidylglycerols, as well as betaine lipids diacylglyceryl-N,N,N-trimethylhomoserines (DGTS).

  15. Extraction, chromatographic and mass spectrometric methods for lipid analysis.

    PubMed

    Pati, Sumitra; Nie, Ben; Arnold, Robert D; Cummings, Brian S

    2016-05-01

    Lipids make up a diverse subset of biomolecules that are responsible for mediating a variety of structural and functional properties as well as modulating cellular functions such as trafficking, regulation of membrane proteins and subcellular compartmentalization. In particular, phospholipids are the main constituents of biological membranes and play major roles in cellular processes like transmembrane signaling and structural dynamics. The chemical and structural variety of lipids makes analysis using a single experimental approach quite challenging. Research in the field relies on the use of multiple techniques to detect and quantify components of cellular lipidomes as well as determine structural features and cellular organization. Understanding these features can allow researchers to elucidate the biochemical mechanisms by which lipid-lipid and/or lipid-protein interactions take place within the conditions of study. Herein, we provide an overview of essential methods for the examination of lipids, including extraction methods, chromatographic techniques and approaches for mass spectrometric analysis.

  16. Mass spectrometric searches for superheavy elements in terrestrial matter

    NASA Astrophysics Data System (ADS)

    Korschinek, Gunther; Kutschera, Walter

    2015-12-01

    Recent searches for traces of long-lived superheavy elements (SHEs) in terrestrial materials by mass spectrometric means are reviewed. Positive evidence for long-lived neutron-deficient Th isotopes in Th and Rg isotopes in Au, and a possible A = 292, Z ∼ 122 nuclide in Th was reported from experiments with Inductively Coupled Plasma Sector Field Mass Spectrometry (ICP-SF-MS). These findings were not confirmed with Accelerator Mass Spectrometry (AMS), with abundance limits lower by several orders of magnitude. In addition, the extensive AMS searches for 42 SHE nuclides (A = 288- 310) around the much discussed "island of stability" (Z = 114, N = 184) in natural Pt, Au, Pb, Bi materials are reviewed. Due to the flatness of the mass distribution and the relatively large bandwidth of the mass acceptance in AMS searches, an effectively much larger number of SHE nuclides was scanned in the respective materials. No positive evidence for the existence of long-lived SHEs (t1/2 >108 yr) with abundance limits of 10-12 to 10-16 was found.

  17. Determination of iodine to compliment mass spectrometric measurements

    SciTech Connect

    Hohorst, F.A.

    1994-11-01

    The dose of iodine-129 to facility personnel and the general public as a result of past, present, and future activities at DOE sites is of continuing interest, WINCO received about 160 samples annually in a variety of natural matrices, including snow, milk, thyroid tissue, and sagebrush, in which iodine-129 is determined in order to evaluate this dose, Currently, total iodine and the isotopic ratio of iodine-127 to iodine-129 are determined by mass spectrometry. These two measurements determine the concentration of iodine-129 in each sample, These measurements require at least 16 h of mass spectrometer operator time for each sample. A variety of methods are available which concentrate and determine small quantities of iodine. Although useful, these approaches would increase both time and cost. The objective of this effort was to determine total iodine by an alternative method in order to decrease the load on mass spectrometry by 25 to 50%. The preparation of each sample for mass spectrometric analysis involves a common step--collection of iodide on an ion exchange bed. This was the focal point of the effort since the results would be applicable to all samples.

  18. Surface acoustic wave nebulization facilitating lipid mass spectrometric analysis.

    PubMed

    Yoon, Sung Hwan; Huang, Yue; Edgar, J Scott; Ting, Ying S; Heron, Scott R; Kao, Yuchieh; Li, Yanyan; Masselon, Christophe D; Ernst, Robert K; Goodlett, David R

    2012-08-07

    Surface acoustic wave nebulization (SAWN) is a novel method to transfer nonvolatile analytes directly from the aqueous phase to the gas phase for mass spectrometric analysis. The lower ion energetics of SAWN and its planar nature make it appealing for analytically challenging lipid samples. This challenge is a result of their amphipathic nature, labile nature, and tendency to form aggregates, which readily precipitate clogging capillaries used for electrospray ionization (ESI). Here, we report the use of SAWN to characterize the complex glycolipid, lipid A, which serves as the membrane anchor component of lipopolysaccharide (LPS) and has a pronounced tendency to clog nano-ESI capillaries. We also show that unlike ESI SAWN is capable of ionizing labile phospholipids without fragmentation. Lastly, we compare the ease of use of SAWN to the more conventional infusion-based ESI methods and demonstrate the ability to generate higher order tandem mass spectral data of lipid A for automated structure assignment using our previously reported hierarchical tandem mass spectrometry (HiTMS) algorithm. The ease of generating SAWN-MS(n) data combined with HiTMS interpretation offers the potential for high throughput lipid A structure analysis.

  19. Mass spectrometric study of the amipurimycin hexopyranosidic sugar moiety

    NASA Astrophysics Data System (ADS)

    Almoster Ferreira, M. A.; Borges, C.; Oliveira, M. C.; Pocsfalvi, G.; Rauter, A. P.; Fernandes, A. C.

    1997-11-01

    Amipurimycin is a natural nucleoside that displays a remarkable activity in vitro and in vivo against Pyricularia oryzae, which is responsible for the rice blast disease. Six important precursors for the synthesis of the Amipurimycin sugar moiety were prepared. In order to obtain structural information a mass spectrometric study of these compounds was performed using liquid secondary ion mass spectrometry (LSIMS) with high-energy collision-induced dissociation (CID) experiments on a four-sector instrument. Elimination of methanol is the preferential fragmentation path for five of the six protonated molecules, indicating that protonation plays an important role in the process, whilst for the other protonated molecule loss of water is the main fragmentation. Examination of the [M + Li]+ precursor ion spectra shows that loss of methanol does not occur in three of them, but in the other three gives rise to fairly abundant ions, indicating that in this case methanol elimination implies intramolecular hydrogen transfer, the resulting ion having a very stable structure.

  20. Enrichment/isolation of phosphorylated peptides on hafnium oxide prior to mass spectrometric analysis.

    PubMed

    Rivera, José G; Choi, Yong Seok; Vujcic, Stefan; Wood, Troy D; Colón, Luis A

    2009-01-01

    Hafnium oxide (hafnia) exhibits unique enrichment properties towards phosphorylated peptides that are complementary to those of titanium oxide (titania) and zirconium oxide (zirconia) for use with mass spectrometric analysis in the field of proteomics.

  1. DEVELOPMENT OF AN ELECTROSPRAY MASS SPECTROMETRIC METHOD FOR DETERMINING PERCHLORATE IN FERTILIZERS

    EPA Science Inventory

    An electrospray mass spectrometric method has been developed for application to agricultural and horticultural fertilizers to determine perchlorate. After fertilizers are leached or dissolved in water, the method relies on the formation of stable ion pair complex of the perchlor...

  2. DEVELOPMENT OF AN ELECTROSPRAY MASS SPECTROMETRIC METHOD FOR DETERMINING PERCHLORATE IN FERTILIZERS

    EPA Science Inventory

    An electrospray mass spectrometric method has been developed for application to agricultural and horticultural fertilizers to determine perchlorate. After fertilizers are leached or dissolved in water, the method relies on the formation of stable ion pair complex of the perchlor...

  3. Status of mass spectrometric radiocarbon detection at ETHZ

    NASA Astrophysics Data System (ADS)

    Seiler, Martin; Maxeiner, Sascha; Wacker, Lukas; Synal, Hans-Arno

    2015-10-01

    A prototype of a mass spectrometric radiocarbon detection instrument without accelerator stage was built for the first time and set into operation at ETH Zurich. The system is designed as an experimental platform to optimize performance of 14C detection at low ion energies and to study the most relevant processes that may limit system performance. The optimized stripper unit incorporates differential pumping to maintain a low gas outflow and a revised tube design to better match the phase space volume of the ion beam at low energies. The system is fully operational and has demonstrated true radiocarbon dating capabilities. The overall beam transmission through the stripper tube is about 40% for the 1+ charge state. Radiocarbon analyses with an overall precision of 0.6% were obtained on a single sample under regular measurement conditions. By analyzing multiple targets of the same sample material an uncertainty level of 0.3% has been reached. The background level corresponds to a radiocarbon age of 40,000 years.

  4. Oxidative Ionization Under Certain Negative-Ion Mass Spectrometric Conditions

    NASA Astrophysics Data System (ADS)

    Hassan, Isra; Pavlov, Julius; Errabelli, Ramu; Attygalle, Athula B.

    2017-02-01

    1,4-Hydroquinone and several other phenolic compounds generate (M - 2) -• radical-anions, rather than deprotonated molecules, under certain negative-ion mass spectrometric conditions. In fact, spectra generated under helium-plasma ionization (HePI) conditions from 1,4-hydroquinone and 1,4-benzoquinone (by electron capture) were practically indistinguishable. Because this process involves a net loss of H• and H+, it can be termed oxidative ionization. The superoxide radical-anion (O2 -•), known to be present in many atmospheric-pressure plasma ion sources operated in the negative mode, plays a critical role in the oxidative ionization process. The presence of a small peak at m/z 142 in the spectrum of 1,4-hydroquinone, but not in that of 1,4-benzoquinone, indicated that the initial step in the oxidative ionization process is the formation of an O2 -• adduct. On the other hand, under bona fide electrospray ionization (ESI) conditions, 1,4-hydroquinone generates predominantly an (M - 1) - ion. It is known that at sufficiently high capillary voltages, corona discharges begin to occur even in an ESI source. At lower ESI capillary voltages, deprotonation predominates; as the capillary voltage is raised, the abundance of O2 -• present in the plasma increases, and the source in turn increasingly behaves as a composite ESI/APCI source. While maintaining post-ionization ion activation to a minimum (to prevent fragmentation), and monitoring the relative intensities of the m/z 109 (due to deprotonation) and 108 (oxidative ionization) peaks recorded from 1,4-hydroquinone, a semiquantitative estimation of the APCI contribution to the overall ion-generation process can be obtained.

  5. Oxidative Ionization Under Certain Negative-Ion Mass Spectrometric Conditions.

    PubMed

    Hassan, Isra; Pavlov, Julius; Errabelli, Ramu; Attygalle, Athula B

    2017-02-01

    1,4-Hydroquinone and several other phenolic compounds generate (M - 2) (-•) radical-anions, rather than deprotonated molecules, under certain negative-ion mass spectrometric conditions. In fact, spectra generated under helium-plasma ionization (HePI) conditions from 1,4-hydroquinone and 1,4-benzoquinone (by electron capture) were practically indistinguishable. Because this process involves a net loss of H(•) and H(+), it can be termed oxidative ionization. The superoxide radical-anion (O2(-•)), known to be present in many atmospheric-pressure plasma ion sources operated in the negative mode, plays a critical role in the oxidative ionization process. The presence of a small peak at m/z 142 in the spectrum of 1,4-hydroquinone, but not in that of 1,4-benzoquinone, indicated that the initial step in the oxidative ionization process is the formation of an O2(-•) adduct. On the other hand, under bona fide electrospray ionization (ESI) conditions, 1,4-hydroquinone generates predominantly an (M - 1) (-) ion. It is known that at sufficiently high capillary voltages, corona discharges begin to occur even in an ESI source. At lower ESI capillary voltages, deprotonation predominates; as the capillary voltage is raised, the abundance of O2(-•) present in the plasma increases, and the source in turn increasingly behaves as a composite ESI/APCI source. While maintaining post-ionization ion activation to a minimum (to prevent fragmentation), and monitoring the relative intensities of the m/z 109 (due to deprotonation) and 108 (oxidative ionization) peaks recorded from 1,4-hydroquinone, a semiquantitative estimation of the APCI contribution to the overall ion-generation process can be obtained. Graphical Abstract ᅟ.

  6. Mass spectrometric characterization of methylaluminoxane-activated metallocene complexes.

    PubMed

    Trefz, Tyler K; Henderson, Matthew A; Linnolahti, Mikko; Collins, Scott; McIndoe, J Scott

    2015-02-09

    Electrospray-ionization mass spectrometric studies of poly(methylaluminoxane) (MAO) in the presence of [Cp2 ZrMe2 ], [Cp2 ZrMe(Cl)], and [Cp2 ZrCl2 ] in fluorobenzene (PhF) solution are reported. The results demonstrate that alkylation and ionization are separate events that occur at competitive rates in a polar solvent. Furthermore, there are significant differences in ion-pair speciation that result from the use of metallocene dichloride complexes in comparison to alkylated precursors at otherwise identical Al/Zr ratios. Finally, the counter anions that form are dependent on the choice of precursor and Al/Zr ratio; halogenated aluminoxane anions [(MeAlO)x (Me3 Al)y-z (Me2 AlCl)z Me](-) (z=1, 2, 3…︁) are observed using metal chloride complexes and under some conditions may predominate over their non-halogenated precursors [(MeAlO)x (Me3 Al)y Me](-) . Specifically, this halogenation process appears selective for the anions that form in comparison to the neutral components of MAO. Only at very high Al/Zr ratios is the same "native" anion distribution observed when using [Cp2 ZrCl2 ] when compared with [Cp2 ZrMe2 ]. Together, the results suggest that the need for a large excess of MAO when using metallocene dichloride complexes is a reflection of competitive alkylation vs. ionization, the persistence of unreactive, homodinuclear ion pairs in the case of [Cp2 ZrCl2 ], as well as a change in ion pairing resulting from modification of the anions formed at lower Al/Zr ratios. Models for neutral precursors and anions are examined computationally.

  7. Measuring masses of large biomolecules and bioparticles using mass spectrometric techniques.

    PubMed

    Peng, Wen-Ping; Chou, Szu-Wei; Patil, Avinash A

    2014-07-21

    Large biomolecules and bioparticles play a vital role in biology, chemistry, biomedical science and physics. Mass is a critical parameter for the characterization of large biomolecules and bioparticles. To achieve mass analysis, choosing a suitable ion source is the first step and the instruments for detecting ions, mass analyzers and detectors should also be considered. Abundant mass spectrometric techniques have been proposed to determine the masses of large biomolecules and bioparticles and these techniques can be divided into two categories. The first category measures the mass (or size) of intact particles, including single particle quadrupole ion trap mass spectrometry, cell mass spectrometry, charge detection mass spectrometry and differential mobility mass analysis; the second category aims to measure the mass and tandem mass of biomolecular ions, including quadrupole ion trap mass spectrometry, time-of-flight mass spectrometry, quadrupole orthogonal time-of-flight mass spectrometry and orbitrap mass spectrometry. Moreover, algorithms for the mass and stoichiometry assignment of electrospray mass spectra are developed to obtain accurate structure information and subunit combinations.

  8. Allatotropin-related peptide in cockroaches: identification via mass spectrometric analysis of single identified neurons.

    PubMed

    Neupert, Susanne; Schattschneider, Sebastian; Predel, Reinhard

    2009-03-01

    The first insect allatotropin-related peptide (ATRP) was isolated from head extracts of the adult sphinx moth Manduca sexta [Kataoka H, Toschi A, Li JP, Carney RL, Schooley DA, Kramer SJ. Identification of an allatotropin from adult Manduca sexta. Science 1989;243:1481-3.]. Meanwhile ATRPs are known from different holometabolous insects but only a single ATRP could be identified from hemimetabolous insects [Paemen L, Tips A, Schoofs L, Proost P, Van Damme J, De Loof A. Lom-AG-myotropin: a novel myotropic peptide from the male accessory glands of Locusta migratoria. Peptides 1991;12:7-10.]. This means that the extensive analysis of neuropeptides from Leucophaea maderae and Periplaneta americana, which led to the discovery of many novel insect neuropeptides, did not result in the detection of any ATRP. In this study, we used another approach to find a cockroach ATRP by first identifying Manse-AT immunoreactive neurons in the terminal ganglion that can be stained by retrograde labeling and are suitable for dissection and subsequent mass spectrometric analysis. The peptidomic analysis of these putative ATRP neurons paved the way for the identification of the first cockroach ATRP. MALDI-TOF/TOF tandem mass spectrometry revealed a sequence identity with Locmi-AG-MT-1 which classifies this ATRP as a highly conserved neuropeptide. A mass spectrometric screening of the nervous system allowed the detection of ATRP-ion signals in different parts of the CNS of P. americana as well as L. maderae. The data obtained in this study will be incorporated in a map of peptidergic neurons from the CNS of the American cockroach, P. americana.

  9. Modular Mass Spectrometric Tool for Analysis of Composition and Phosphorylation of Protein Complexes

    PubMed Central

    Blethrow, Justin D.; Tang, Chao; Deng, Changhui; Krutchinsky, Andrew N.

    2007-01-01

    The combination of high accuracy, sensitivity and speed of single and multiple-stage mass spectrometric analyses enables the collection of comprehensive sets of data containing detailed information about complex biological samples. To achieve these properties, we combined two high-performance matrix-assisted laser desorption ionization mass analyzers in one modular mass spectrometric tool, and applied this tool for dissecting the composition and post-translational modifications of protein complexes. As an example of this approach, we here present studies of the Saccharomyces cerevisiae anaphase-promoting complexes (APC) and elucidation of phosphorylation sites on its components. In general, the modular concept we describe could be useful for assembling mass spectrometers operating with both matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) ion sources into powerful mass spectrometric tools for the comprehensive analysis of complex biological samples. PMID:17406682

  10. Mass spectrometric monitoring of interfacial photoelectron transfer and imaging of active crystalline facets of semiconductors

    NASA Astrophysics Data System (ADS)

    Zhong, Hongying; Zhang, Juan; Tang, Xuemei; Zhang, Wenyang; Jiang, Ruowei; Li, Rui; Chen, Disong; Wang, Peng; Yuan, Zhiwei

    2017-02-01

    Monitoring of interfacial electron transfer (ET) in situ is important to understand the ET mechanism and designing efficient photocatalysts. We describe herein a mass spectrometric approach to investigate the ultrafast transfer of photoelectrons that are generated by ultraviolet irradiation on surfaces of semiconductor nanoparticles or crystalline facets. The mass spectrometric approach can not only untargetedly detect various intermediates but also monitor their reactivity through associative or dissociative photoelectron capture dissociation, as well as electron detachment dissociation of adsorbed molecules. Proton-coupled electron transfer and proton-uncoupled electron transfer with radical initiated polymerization or hydroxyl radical abstraction have been unambiguously demonstrated with the mass spectrometric approach. Active crystalline facets of titanium dioxide for photocatalytic degradation of juglone and organochlorine dichlorodiphenyltrichloroethane are visualized with mass spectrometry imaging based on ion scanning and spectral reconstruction. This work provides a new technique for studying photo-electric properties of various materials.

  11. Mass spectrometric monitoring of interfacial photoelectron transfer and imaging of active crystalline facets of semiconductors

    PubMed Central

    Zhong, Hongying; Zhang, Juan; Tang, Xuemei; Zhang, Wenyang; Jiang, Ruowei; Li, Rui; Chen, Disong; Wang, Peng; Yuan, Zhiwei

    2017-01-01

    Monitoring of interfacial electron transfer (ET) in situ is important to understand the ET mechanism and designing efficient photocatalysts. We describe herein a mass spectrometric approach to investigate the ultrafast transfer of photoelectrons that are generated by ultraviolet irradiation on surfaces of semiconductor nanoparticles or crystalline facets. The mass spectrometric approach can not only untargetedly detect various intermediates but also monitor their reactivity through associative or dissociative photoelectron capture dissociation, as well as electron detachment dissociation of adsorbed molecules. Proton-coupled electron transfer and proton-uncoupled electron transfer with radical initiated polymerization or hydroxyl radical abstraction have been unambiguously demonstrated with the mass spectrometric approach. Active crystalline facets of titanium dioxide for photocatalytic degradation of juglone and organochlorine dichlorodiphenyltrichloroethane are visualized with mass spectrometry imaging based on ion scanning and spectral reconstruction. This work provides a new technique for studying photo-electric properties of various materials. PMID:28224986

  12. Mass Spectrometric Characteristics of Prenylated Indole Derivatives from Marine-Derived Penicillium sp. NH-SL

    PubMed Central

    Ding, Hui; Ding, Wanjing; Ma, Zhongjun

    2017-01-01

    Two prenylated indole alkaloids were isolated from the ethyl acetate extracts of a marine-derived fungus Penicillium sp. NH-SL and one of them exhibited potent cytotoxic activity against mouse hepa 1c1c7 cells. In order to detect other bioactive analogs, we used liquid chromatogram tandem mass spectrometry (LC-MS/MS) to analyze the mass spectrometric characteristics of the isolated compounds as well as the crude extracts. As a result, three other analogs were detected, and their structures were deduced according to the similar fragmentation patterns. This is the first systematic report on the mass spectrometric characteristics of prenylated indole derivatives. PMID:28327529

  13. Mass Spectrometric Characteristics of Prenylated Indole Derivatives from Marine-Derived Penicillium sp. NH-SL.

    PubMed

    Ding, Hui; Ding, Wanjing; Ma, Zhongjun

    2017-03-22

    Two prenylated indole alkaloids were isolated from the ethyl acetate extracts of a marine-derived fungus Penicillium sp. NH-SL and one of them exhibited potent cytotoxic activity against mouse hepa 1c1c7 cells. In order to detect other bioactive analogs, we used liquid chromatogram tandem mass spectrometry (LC-MS/MS) to analyze the mass spectrometric characteristics of the isolated compounds as well as the crude extracts. As a result, three other analogs were detected, and their structures were deduced according to the similar fragmentation patterns. This is the first systematic report on the mass spectrometric characteristics of prenylated indole derivatives.

  14. Structure elucidation of metabolite x17299 by interpretation of mass spectrometric data.

    PubMed

    Zhang, Qibo; Ford, Lisa A; Evans, Anne M; Toal, Douglas R

    2017-01-01

    A major bottleneck in metabolomic studies is metabolite identification from accurate mass spectrometric data. Metabolite x17299 was identified in plasma as an unknown in a metabolomic study using a compound-centric approach where the associated ion features of the compound were used to determine the true molecular mass. The aim of this work is to elucidate the chemical structure of x17299, a new compound by de novo interpretation of mass spectrometric data. An Orbitrap Elite mass spectrometer was used for acquisition of mass spectra up to MS(4) at high resolution. Synthetic standards of N,N,N-trimethyl-l-alanyl-l-proline betaine (l,l-TMAP), a diastereomer, and an enantiomer were chemically prepared. The planar structure of x17299 was successfully proposed by de novo mechanistic interpretation of mass spectrometric data without any laborious purification and nuclear magnetic resonance spectroscopic analysis. The proposed structure was verified by deuterium exchanged mass spectrometric analysis and confirmed by comparison to a synthetic standard. Relative configuration of x17299 was determined by direct chromatographic comparison to a pair of synthetic diastereomers. Absolute configuration was assigned after derivatization of x17299 with a chiral auxiliary group followed by its chromatographic comparison to a pair of synthetic standards. The chemical structure of metabolite x17299 was determined to be l,l-TMAP.

  15. Combined chromatographic and mass spectrometric toolbox for fingerprinting migration from PET tray during microwave heating.

    PubMed

    Alin, Jonas; Hakkarainen, Minna

    2013-02-13

    A combined chromatographic and mass spectrometric toolbox was utilized to determine the interactions between poly(ethylene terephthalate) (PET) food packaging and different food simulants during microwave heating. Overall and specific migration was determined by combining weight loss measurements with gas chromatography-mass spectrometry (GC-MS) and electrospray ionization mass spectrometry (ESI-MS). This allowed mapping of low molecular weight migrants in the molecular range up to 2000 g/mol. Microwave heating caused significantly faster migration of cyclic oligomers into ethanol and isooctane as compared to migration during conventional heating at the same temperature. This effect was more significant at lower temperature at which diffusion rates are generally lower. It was also shown that transesterification took place between PET and ethanol during microwave heating, leading to formation of diethyl terephthalate. The detected migrants included cyclic oligomers from dimer to hexamer, in most cases containing extra ethylene glycol units, and oxidized Irgafos 168. ESI-MS combined with CID MS-MS was an excellent tool for structural interpretation of the nonvolatile compounds migrating to the food simulants. The overall migration was below the overall migration limit of 10 mg/dm(2) set by the European commission after 4 h of microwave heating at 100 °C in all studied food simulants.

  16. Systematic studies of the mass spectrometric properties of alkaline earth metal cationized amino acids and peptides

    NASA Astrophysics Data System (ADS)

    Küjckelmann, Ulrich; Müller, Dietrich; Weber, Carsten

    1997-07-01

    The results of a systematic study of the gas phase interactions of α-amino acids and peptides (4-15 amino acids) with alkaline earth metals, observed with mass spectrometric techniques, are presented. Furthermore, a model for the cationization with calcium at the C-terminal amino acid arginine in rotaviral polypeptides is presented.

  17. Differentiating organic from conventional peppermints using chromatographic and flow-injection mass spectrometric (FIMS) fingerprints

    USDA-ARS?s Scientific Manuscript database

    High performance liquid chromatography (HPLC) and flow-injection mass spectrometric (FIMS) fingerprinting techniques were tested for their potential in differentiating organic and conventional peppermint samples. Ten organic and ten conventional peppermint samples were examined using HPLC-UV and FI...

  18. Mass spectrometric methods for the direct elemental and isotopic analysis of solid material

    NASA Astrophysics Data System (ADS)

    Ganeev, A. A.; Gubal, A. R.; Potapov, S. V.; Agafonova, N. N.; Nemets, V. M.

    2016-04-01

    Methods for the direct analysis of solids have a number of undeniable advantages over the methods that require preliminary dissolution of samples. High sensitivity and selectivity make the direct mass spectrometric techniques the most in-demand. The review concerns spark source mass spectrometry, laser ionization mass spectrometry, laser ablation inductively coupled plasma mass spectrometry, secondary ion mass spectrometry, secondary neutral mass spectrometry and glow discharge mass spectrometry. Basic principles, analytical characteristics and trends in the development of these techniques are discussed. Particular attention is given to applications of the techniques as well as to their competitive advantages and drawbacks. The bibliography includes 123 references.

  19. Liquid chromatography-mass spectrometric and liquid chromatography-tandem mass spectrometric determination of hallucinogenic indoles psilocin and psilocybin in "magic mushroom" samples.

    PubMed

    Kamata, Tooru; Nishikawa, Mayumi; Katagi, Munehiro; Tsuchihashi, Hitoshi

    2005-03-01

    Accurate and sensitive analytical methods for psilocin (PC) and psilocybin (PB), tryptamine-type hallucinogens contained in "magic mushrooms," were investigated using liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS-MS). The chromatographic separation on an ODS column and mass spectral information gave complete discrimination between PC and PB without derivatization. The mass spectrometric detection had a high sensitivity, and the tandem mass spectrometric detection provided more specificity and accuracy, as well as high sensitivity. The detection limits ranged from 1 to 25 pg by LC-MS in the selected ion monitoring mode, and the intra- and inter-day coefficients of variation were estimated to be 4.21-5.93% by LC-MS-MS in the selected reaction monitoring mode. By applying the present LC-MS-MS technique to four real samples, the contents of PC and PB were found to vary over a wide range (0.60-1.4 and 0.18-3.8 mg/g dry wt. for PC and PB, respectively) between samples.

  20. Mass spectrometric approaches to study protein structure and interactions in lyophilized powders.

    PubMed

    Moorthy, Balakrishnan S; Iyer, Lavanya K; Topp, Elizabeth M

    2015-04-14

    Amide hydrogen/deuterium exchange (ssHDX-MS) and side-chain photolytic labeling (ssPL-MS) followed by mass spectrometric analysis can be valuable for characterizing lyophilized formulations of protein therapeutics. Labeling followed by suitable proteolytic digestion allows the protein structure and interactions to be mapped with peptide-level resolution. Since the protein structural elements are stabilized by a network of chemical bonds from the main-chains and side-chains of amino acids, specific labeling of atoms in the amino acid residues provides insight into the structure and conformation of the protein. In contrast to routine methods used to study proteins in lyophilized solids (e.g., FTIR), ssHDX-MS and ssPL-MS provide quantitative and site-specific information. The extent of deuterium incorporation and kinetic parameters can be related to rapidly and slowly exchanging amide pools (N fast, N slow) and directly reflects the degree of protein folding and structure in lyophilized formulations. Stable photolytic labeling does not undergo back-exchange, an advantage over ssHDX-MS. Here, we provide detailed protocols for both ssHDX-MS and ssPL-MS, using myoglobin (Mb) as a model protein in lyophilized formulations containing either trehalose or sorbitol.

  1. Mass spectrometric analysis of the volatiles released by heating or crushing rocks

    NASA Technical Reports Server (NTRS)

    Barker, C.; Sommer, M. A.

    1973-01-01

    Vacuum extraction with subsequent mass spectrometric analysis of evolved volatiles was selected as the analytical procedure. The high-vacuum gas-handling system was constructed of stainless steel. The system was completely free from mercury, grease, or volatile organic materials. The furnace for heating the samples is discussed together with the high-vacuum crusher, the mass spectrometer, and approaches for water determination. The analytical procedure is considered, giving attention to the extraction of volatiles, adsorption studies, and the analysis of volatiles.

  2. Development and application of a mass spectrometric system to study volatile components of fluid inclusions

    SciTech Connect

    Sloan, Jr., Richard Charles

    1992-06-01

    A quadrupole mass spectrometric system coupled with mechanical decrepitation was constructed and calibrated to study fluid inclusions from an active geothermal system. Fluid inclusions in Salton Sea Scientific Drilling Project well cores and ejects from flow tests were analyzed. Ion currents from selected mass/charge ratio numbers were measured for gases from ruptured inclusions in epidote, calcite, and hematite vein minerals from different depths. Water, carbon dioxide, hydrogen sulfide, sulfur dioxide, and C1-C4+ hydrocarbons and free nitrogen were analyzed.

  3. Remote mass spectrometric sampling of electrospray- and desorption electrospray-generated ions using an air ejector.

    PubMed

    Dixon, R Brent; Bereman, Michael S; Muddiman, David C; Hawkridge, Adam M

    2007-10-01

    A commercial air ejector was coupled to an electrospray ionization linear ion trap mass spectrometer (LTQ) to transport remotely generated ions from both electrospray (ESI) and desorption electrospray ionization (DESI) sources. We demonstrate the remote analysis of a series of analyte ions that range from small molecules and polymers to polypeptides using the AE-LTQ interface. The details of the ESI-AE-LTQ and DESI-AE-LTQ experimental configurations are described and preliminary mass spectrometric data are presented.

  4. [Mass spectrometric analysis of polycyclic aromatic hydrocarbons adducted to DNA]. Final report

    SciTech Connect

    Barofsky, D.F.

    1992-12-31

    Studies described herein sought and to synthesize PAH-adducted residues of DNA to serve as models for carrying out the mass spectrometric studies; to construct and test a high performance, pulsed ion bombardment, time-of-flight (TOF) mass spectrometer; to initiate an investigation of the efficacy of using thin wire sample holders to increase sensitivity and focused ion beam bombardment to increase ion yield and ion transmission; and to initiate an investigation of sensitivity enhancing matrices for PAH-adducted DNA.

  5. Mass spectrometric determination of the composition of the Venus clouds

    NASA Technical Reports Server (NTRS)

    Herzog, R. F. K.

    1973-01-01

    The instrumentation is analyzed for determining the composition of the clouds on Venus. Direct analysis of the gas phase atmosphere, and the detection of ferrous chloride with a mass spectrometer are dicussed along with the mass analyzer, and the pre-separation of cloud particles from the ambient atmosphere.

  6. High-resolution mass spectrometric analysis of biomass pyrolysis vapors

    DOE PAGES

    Christensen, Earl; Evans, Robert J.; Carpenter, Daniel

    2017-01-19

    Vapors generated from the pyrolysis of lignocellulosic biomass are made up of a complex mixture of oxygenated compounds. Direct analysis of these vapors provides insight into the mechanisms of depolymerization of cellulose, hemicellulose, and lignin as well as insight into reactions that may occur during condensation of pyrolysis vapors into bio-oil. Studies utilizing pyrolysis molecular beam mass spectrometry have provided valuable information regarding the chemical composition of pyrolysis vapors. Mass spectrometers generally employed with these instruments have low mass resolution of approximately a mass unit. The presence of chemical species with identical unit mass but differing elemental formulas cannot bemore » resolved with these instruments and are therefore detected as a single ion. In this study we analyzed the pyrolysis vapors of several biomass sources using a high-resolution double focusing mass spectrometer. High-resolution analysis of pyrolysis vapors allowed for speciation of several compounds that would be detected as a single ion with unit mass resolution. Lastly, these data not only provide greater detail into the composition of pyrolysis vapors but also highlight differences between vapors generated from multiple biomass feedstocks.« less

  7. Mass-spectrometric study of benzopyridosilaazepines and -azepinones

    SciTech Connect

    Shevtsov, V.K.; Varlamov, A.V.; Poshivalov, S.G.; Simonova, L.A.; Prostakov, N.S.

    1986-11-01

    The influence of various structural factors on the dissociative ionization of benzopyridosilaazepines and -azepinones has been investigated. It has been shown that the mass spectra can be used to identify isomeric benzopyridosilaazepinones with respect to the position of the amide fragment in the central heterocycle. The anomalously high intensity of the ion (M - H) in the mass spectra of these compounds is attributed to fragmentation of the molecular ions from the open form.

  8. Electrospray ionization mass spectrometric characterization of acrylamide adducts to hemoglobin

    SciTech Connect

    Springer, D.L.; Goheen, S.C.; Edmonds, C.G. ); Bull, R.J.; Sylvester, D.M. )

    1993-01-01

    The most common procedure to identify hemoglobin adducts has been to cleave the adducts from the protein and characterize the adducting species, by, for example, derivatization and gas chromatography/mass spectrometry. To extend these approaches we used electrospray ionization mass spectrometry (ESI-MS) to characterize adducted hemoglobin. For this we incubated [[sup 14]C]acrylamide with the purified human hemoglobin (type A[sub 0]) under conditions that yielded high adduct levels. When the hemoglobin was separated by reversed-phase high-performance liquid chromatography (HPLC), 65% of the radioactivity copurified with the [beta]-subunit. Three adducted species were prominent in the ESI mass spectrum of the intact [beta]-subunit, indicating acrylamide adduction (i.e., mass increase of 71 Da) and two addition unidentified moieties with mass increments of 102 and 135 Da. Endoproteinase Glu-C digestion of the adducted [beta]-subunit resulted in a peptide mixture that, upon reversed-phase HPLC separation, provided several radiolabeled peptides. Using ESI-MS we identified these as the V[sub 91-101] and V[sub 102-122] peptides that represent the cysteine-containing peptides of the [beta]-subunit. These results provide definitive information on acrylamide-modified human hemoglobin and demonstrate that ESI-MS provides valuable structure information on chemically adducted proteins. 30 refs., 9 figs., 3 tabs.

  9. Mass spectrometric studies on the interaction of cisplatin and insulin.

    PubMed

    Li, Jing; Yue, Lei; Liu, Yaqin; Yin, Xinchi; Yin, Qi; Pan, Yuanjiang; Yang, Lirong

    2016-04-01

    The interaction of antitumor drug, cisplatin (cis-[PtCl2(NH3)2], CDDP) with insulin from porcine pancreas has been investigated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and high resolution hybrid ion trap/time-of-flight mass spectrometry (MALIDI-TOF/TOF-MS and ESI-IT/TOF MS). The MALDI-TOF/TOF-MS results demonstrated that the presence of cisplatin complex resulted in the reduction of the disulfide bond in porcine pancreas after the incubations of the two substances were performed in vitro. It indicated that the presence of cisplatin would destroy the native configuration of insulin, which may lead to the inactivation of insulin. High resolution mass values and the characteristic isotopic pattern of the platinated insulin ions allowed the analysis of platinated mono-, di- and triadducts of cisplatin and insulin in the incubations under different conditions. The laser-induced dissociation of the monoadduct obtained in MALDI source was carried out and one platinum was found to bind to insulin B chain was determined. The platinum binding sites were further identified to be the N terminus (B chain), cysteine 7 (B chain) and cysteine 19 (B chain) residues by electrospray ionization tandem mass spectrometry. The identification of the interaction between insulin and cisplatin broadens the horizon of the knowledge in the interaction of the proteins and metallodrugs.

  10. Mass Spectrometric Monitoring of Animal Feed for BSE Spread

    ERIC Educational Resources Information Center

    King, Angela G.

    2004-01-01

    The researchers in London have developed an emerging technology that utilizes mass spectrometry to detect processed animal protein (PAP) in animal feed. The amount of animal protein in the feed can be determined by the ratio of the hydrolyzed gelatine signal at m/z 1044 to an internal standard signal at m/z 556.

  11. Mass Spectrometric Approaches to Detecting and Quantifying Prions

    USDA-ARS?s Scientific Manuscript database

    Until recently, the use of mass spectrometry has been limited to identifying covalent posttranslational modifications of PrPSc and PrPC. These efforts support the hypothesis that PrPC and PrPSc possess identical covalent posttranslational modifications. Technical advances in instrumentation now all...

  12. Mass spectrometric analysis of protein–ligand interactions

    PubMed Central

    Ishii, Kentaro; Noda, Masanori; Uchiyama, Susumu

    2016-01-01

    The interactions of small molecules with proteins (protein–ligand interactions) mediate various biological phenomena including signal transduction and protein transcription and translation. Synthetic compounds such as drugs can also bind to target proteins, leading to the inhibition of protein–ligand interactions. These interactions typically accompany association–dissociation equilibrium according to the free energy difference between free and bound states; therefore, the quantitative biophysical analysis of the interactions, which uncovers the stoichiometry and dissociation constant, is important for understanding biological reactions as well as for rational drug development. Mass spectrometry (MS) has been used to determine the precise molecular masses of molecules. Recent advancements in MS enable us to determine the molecular masses of protein–ligand complexes without disrupting the non-covalent interactions through the gentle desolvation of the complexes by increasing the vacuum pressure of a chamber in a mass spectrometer. This method is called MS under non-denaturing conditions or native MS and allows the unambiguous determination of protein–ligand interactions. Under a few assumptions, MS has also been applied to determine the dissociation constants for protein–ligand interactions. The structural information of a protein–ligand interaction, such as the location of the interaction and conformational change in a protein, can also be analyzed using hydrogen/deuterium exchange MS. In this paper, we briefly describe the history, principle, and recent applications of MS for the study of protein–ligand interactions. PMID:27924262

  13. Mass Spectrometric Monitoring of Animal Feed for BSE Spread

    ERIC Educational Resources Information Center

    King, Angela G.

    2004-01-01

    The researchers in London have developed an emerging technology that utilizes mass spectrometry to detect processed animal protein (PAP) in animal feed. The amount of animal protein in the feed can be determined by the ratio of the hydrolyzed gelatine signal at m/z 1044 to an internal standard signal at m/z 556.

  14. Extending the frontiers of mass spectrometric instrumentation and methods

    SciTech Connect

    Schieffer, Gregg Martin

    2010-01-01

    The focus of this dissertation is two-fold: developing novel analysis methods using mass spectrometry and the implementation and characterization of a novel ion mobility mass spectrometry instrumentation. The novel mass spectrometry combines ion trap for ion/ion reactions coupled to an ion mobility cell. The long term goal of this instrumentation is to use ion/ion reactions to probe the structure of gas phase biomolecule ions. The three ion source - ion trap - ion mobility - qTOF mass spectrometer (IT - IM - TOF MS) instrument is described. The analysis of the degradation products in coal (Chapter 2) and the imaging plant metabolites (Appendix III) fall under the methods development category. These projects use existing commercial instrumentation (JEOL AccuTOF MS and Thermo Finnigan LCQ IT, respectively) for the mass analysis of the degraded coal products and the plant metabolites, respectively. The coal degradation paper discusses the use of the DART ion source for fast and easy sample analysis. The sample preparation consisted of a simple 50 fold dilution of the soluble coal products in water and placing the liquid in front of the heated gas stream. This is the first time the DART ion source has been used for analysis of coal. Steven Raders under the guidance of John Verkade came up with the coal degradation projects. Raders performed the coal degradation reactions, worked up the products, and sent them to me. Gregg Schieffer developed the method and wrote the paper demonstrating the use of the DART ion source for the fast and easy sample analysis. The plant metabolite imaging project extends the use of colloidal graphite as a sample coating for atmospheric pressure LDI. DC Perdian and I closely worked together to make this project work. Perdian focused on building the LDI setup whereas Schieffer focused on the MSn analysis of the metabolites. Both Perdian and I took the data featured in the paper. Perdian was the primary writer of the paper and used it as a

  15. A mass spectrometric analysis of {gamma}-GPS films

    SciTech Connect

    Dillingham, R.G.; Boerio, F.J.; Bertelsen, C.; Savina, M.R.; Lykke, K.R.; Calaway, W.F.

    1996-06-01

    {gamma}-glycidoxypropyltrimethoxysilane ({gamma}-GPS) is used for pre-treatment of grit-blasted aluminum before adhesive bonding. This paper discusses analysis of non-reflective grit-blasted surfaces using mass spectrometry of species that were either sputtered off using an ion beam or thermally desorbed as neutrals using a pulsed laser and then post-ionized using a secondary laser. Results show that fragmentation is excessive and structural information is difficult to obtain from the spectra.

  16. QUANTITATIVE MASS SPECTROMETRIC ANALYSIS OF GLYCOPROTEINS COMBINED WITH ENRICHMENT METHODS

    PubMed Central

    Ahn, Yeong Hee; Kim, Jin Young; Yoo, Jong Shin

    2015-01-01

    Mass spectrometry (MS) has been a core technology for high sensitive and high-throughput analysis of the enriched glycoproteome in aspects of quantitative assays as well as qualitative profiling of glycoproteins. Because it has been widely recognized that aberrant glycosylation in a glycoprotein may involve in progression of a certain disease, the development of efficient analysis tool for the aberrant glycoproteins is very important for deep understanding about pathological function of the glycoprotein and new biomarker development. This review first describes the protein glycosylation-targeting enrichment technologies mainly employing solid-phase extraction methods such as hydrizide-capturing, lectin-specific capturing, and affinity separation techniques based on porous graphitized carbon, hydrophilic interaction chromatography, or immobilized boronic acid. Second, MS-based quantitative analysis strategies coupled with the protein glycosylation-targeting enrichment technologies, by using a label-free MS, stable isotope-labeling, or targeted multiple reaction monitoring (MRM) MS, are summarized with recent published studies. © 2014 The Authors. Mass Spectrometry Reviews Published by Wiley Periodicals, Inc. Rapid Commun. Mass Spec Rev 34:148–165, 2015. PMID:24889823

  17. Mass Spectrometric Measurement of Martian Krypton and Xenon Isotopic Abundance

    NASA Technical Reports Server (NTRS)

    Mahaffy, P.; Mauersberger, K.

    1993-01-01

    The Viking gas chromatograph mass spectrometer experiment provided significant data on the atmospheric composition at the surface of Mars, including measurements of several isotope ratios. However, the limited dynamic range of this mass spectrometer resulted in marginal measurements for the important Kr and Xe isotopic abundance. The Xe-129 to Xe-132 ratio was measured with an uncertainty of 70%, but none of the other isotope ratios for these species were obtained. Accurate measurement of the Xe and Kr isotopic abundance in this atmosphere provides an important data point in testing theories of planetary formation and atmospheric evolution. The measurement is also essential for a stringent test for the Martian origin of the SNC meteorites, since the Kr and Xe fractionation pattern seen in gas trapped in glassy nodules of an SNC (EETA 79001) is unlike any other known solar system resevoir. Current flight mass spectrometer designs combined with the new technology of a high-performance vacuum pumping system show promise for a substantial increase in gas throughput and the dynamic range required to accurately measure these trace species. Various aspects of this new technology are discussed.

  18. A mass spectrometric study of gasoline anti-knocking additives

    NASA Astrophysics Data System (ADS)

    Apicella, B.; di Palma, T. M.; Wang, X.; Velotta, R.; Armenante, M.; Spinelli, N.

    2007-04-01

    Methyl tert-butyl ether (MTBE) is the most widely used additive for gasoline as it is able to increase the oxygen content and to improve the efficiency in the internal combustion engine, controlling the autoignition. Most of the experimental studies performed on MTBE give information only on neutral particle reaction schemes, preventing a complete understanding of the oxidation and pyrolisis reaction chemistry of MTBE in extreme conditions like for example those experienced in the reactions involved in a knocking engine during the spark ignition. In the Part I of this work electron impact ionisation of MTBE has been studied in the range 25-150 eV by means of a time of flight mass spectrometry (TOF-MS). Total ionisation cross-section for MTBE and for all the ions formed from its fragmentation are evaluated relatively to Argon cross-section. What is learned by studying processes which can be understandable within a mass spectrometer can be applied to larger more applied systems, where the extreme conditions prevent an experimental study of the ion chemistry. In the present study the MTBE cross-sections trends and the isotopic study of deuterated MTBE (MTBE-d3) mass spectrum allowed to suggest reaction pathways for MTBE fragmentation. This work will be extended to other two ether molecules, ETBE and TAME, that have been proposed in place of MTBE and the results will be described in the Part II of this paper.

  19. Mass spectrometric detection of solid and vapor explosive materials

    NASA Astrophysics Data System (ADS)

    Stott, William R.; Green, D.; Mercado, Alvaro G.

    1994-10-01

    The detection by chemical sensors of explosive devices in a terrorist or contraband scenario usually involves the acquisition of material in the vapor or solid form. Whether in the vapor form in ambient air or in solid form in a matrix of innocuous material, the chemical compounds may be present at very low concentrations or may be present in concentrations higher by orders of magnitude. In this study, a characterization of a tandem mass spectrometer detection system has been made to evaluate a variety of parameters as it relates to explosive chemicals in both the vapor and solid phases. In particular, a range of concentrations of standard solutions of RDX, PETN and TNT have been injected in determine the sensitivity, dynamic range, and lower level of detection of the SCIEX contraband tandem quadrupole mass spectrometer. Techniques for the introduction of samples include heated nebulization and direct injection/thermal desorption from a real time sampler belt. As well, explosive vapors produced by a special generator were injected in a 1 l/min stream of room air and used to characterize instrumental performance. Solid material was presented in a form simulating fingerprint material and then transferred to the detector using a real time sampling system and then thermally desorbed into the mass spectrometer ionization chamber.

  20. Comparison of mass spectrometric techniques for generating molecular weight information on a class of ethoxylated oligomers.

    PubMed

    Parees, D M; Hanton, S D; Clark, P A; Willcox, D A

    1998-04-01

    The results of fast atom bombardment (FAB), time-of-flight secondary ion mass spectrometry (ToF-SIMS), matrix-assisted laser desorption/ionization (MALD/I), electrospray ionization (ESI), and field desorption (FD) analyses of ethoxylated oligomers of 2,4,7,9-tetramethyl-5-decyne-4,7-diol (Surfynol(®) 104) were compared.Each of these desorption mass spectrometry (MS) techniques can produce spectra of unfragmented cationized oligomers. From the observed ion series we calculate average molecular weight information. We have compared the results of mass spectrometric analyses of a series of ethoxylated Surfynol surfactants. Our data indicate that FAB, ToF-SIMS, MALDI/I, and ESI produce similar results for the lower molecular weight species, but that as the average molecular weight increases FAB and SIMS produce slightly lower results than MALD/I and FD. This could be due to increased fragmentation. ESI produced a result similar to FAB and SIMS for the highest average molecular weight material. Further experiments compare the mass spectral results with gas chromatographic quantitative data. Although gas chromatography is not expected to accurately analyze the higher mass oligomers, we observe significant differences in intensities of the short-chain oligomers (especially the 0- and 1-mers) when compared to the desorption mass spectrometer results. These differences may reflect poor cationization efficiency for very short oligomer chains in the mass spectrometric analyses.

  1. Synthesis and Mass Spectrometric Characterization of Organic Nitrates

    NASA Astrophysics Data System (ADS)

    Grünert, A.; Woidich, S.; Ballschmiter, K.

    2003-04-01

    Organic nitrates, as trace constituents in urban air, can be analyzed by adsorptive low volume sampling (LVS) as well as by adsorptive high volume sampling (HVS). Air samples ranging from 25 L to 100 L for the LVS and 100 m3 to 500 m3 for the (HVS) were collected, respectively. Analysis is performed by thermodesorption (LVS) or solvent elution combined with group separation (HVS) using normal-phase HPLC and high resolution capillary gas chromatography with electron capture detection (HRGC-ECD) and mass selective detection (HRGC-MSD). For identification and quantification available reference compounds are required for both methods (1;2). Following numbers of congeners of organic nitrate have been synthesized: 77 monoalkyl nitrates (C1-C16), 43 dialkyl nitrates (C2-C10), 37 hydroxy alkyl nitrates (C2-C8) and 41 carbonyl alkyl nitrates (C3-C12). Alkanes, alkenes, alcohols, ketones and halocarbons have been used as precursors. Characterisation of the reference compounds by retention-data and mass-spectra was performed by high resolution capillary gas chromatography with mass selective detection in the EI- and the NCI (CH4) mode (1-3). EI-ionization leads to the dominating indicator ion NO2+ for organic nitrates with m/z = 46 u. The characteristic fragments with NCI (CH4) show ions at m/z = 46 u and m/z = 62 u, corresponding to NO2- and NO3-. The use of flame ionisation detection (HRGC-FID) and the principle of the molar response for carbon allows the quantitation of reference solutions as the final tool for the determination of the levels and patterns of organic nitrates in urban air samples. (1) J. Kastler: "Analytik, Massenspektrometrie und Vorkommen multifunktioneller Alkylnitrate in belasteter und unbelasteter Atmosphäre" Dr.rer.nat.-Thesis, University of Ulm (1999) (2) G. Werner, J. Kastler, R. Looser, K. Ballschmiter: "Organic Nitrates of Isoprenes as Atmospheric Trace Compounds" Angew. Chem. Int. Ed. (1999) 38(11): 1634-1637 (3) S.Woidich, O. Froscheis, O

  2. Molecular beam, mass spectrometric sampling in hazardous waste destruction

    SciTech Connect

    Nimlos, M.R.; Milne, T.A.; McKinnon, J.T.

    1995-03-01

    This paper describes the study of the destruction of hazardous waste in which compounds and conditions are screened and byproducts are detected with a molecular beam, mass spectrometer (MBMS). Three destruction techniques were investigated as potential solar-driven processes: catalytic steam reforming, photothermal oxidation, and photocatalytic oxidation. These processes were investigated using an MBMS-equipped with a triple quadrupole mass spectrometer. The MS/MS capabilities of this instrument were used to characterize products using daughter and parent ion scanning modes. With catalytic steam reforming, a number of chlorinated and nonchlorinated compounds were screened for their susceptibility to destruction using a rhodium catalyst. The destruction efficiencies were high at modest temperatures (700-900{degrees}C) and few byproducts were measured. Choloronaphthalene was studied as a model compound for the photothermal oxidation processes. An enhancement in the destruction rate in air was measured by adding near UV light (300-340 nm). Byproducts were measured and the identities of these products were determined using daughter ion MS/MS spectrometry. The gas-phase photocatalytic oxidation of trichloroethylene (TCE) was measured at ambient temperatures using the MBMS. The identity of these byproducts was determined using parent ion MS/MS spectrometry.

  3. Mass spectrometric measurements of the isotopic anatomies of molecules (Invited)

    NASA Astrophysics Data System (ADS)

    Eiler, J. M.; Krumwiede, D.; Schlueter, H.

    2013-12-01

    Site-specific and multiple isotopic substitutions in molecular structures potentially provide an extraordinarily rich set of constraints on their sources, conditions of formation, reaction and transport histories, and perhaps other issues. Examples include carbonate ';clumped isotope' thermometry, clumped isotope measurements of CO2, O2, and, recently, methane, ethane and N2O; site-specific 15N measurements in N2O and 13C and D analyses of fatty acids, sugars, cellulose, food products, and, recently, n-alkanes. Extension of the principles behind these tools to the very large number of isotopologues of complex molecules could potentially lead to new uses of isotope chemistry, similar to proteomics, metabolomics and genomics in their complexity and depth of detail (';isotomics'?). Several technologies are potentially useful for this field, including ';SNIF-NMR', gas source mass spectrometry and IR absorption spectroscopy. However, all well established methods have restrictive limits in the sizes of samples, types of analyzes, and the sorts of isotopologues that can be measured with useful precision. We will present an overview of several emerging instruments and techniques of high-resolution gas source mass spectrometry that may enable study of a large proportion of the isotopologues of a wide range of volatile and semi-volatile compounds, including many organics, with precisions and sample sizes suitable for a range of applications. A variety of isotopologues can be measured by combining information from the Thermo 253 Ultra (a new high resolution, multi-collector gas source mass spectrometer) and the Thermo DFS (a very high resolution single collector, but used here on a novel mode to achieve ~per mil precision ratio measurements), sometimes supplemented by conventional bulk isotopic measurements. It is possible to design methods in which no one of these sources of data meaningfully constrain abundances of specific isotopologues, but their combination fully and

  4. A membrane-separator interface for mass-spectrometric analysis of blood plasma

    NASA Astrophysics Data System (ADS)

    Elizarov, A. Yu.; Gerasimov, D. G.

    2014-09-01

    We demonstrate the possibility of rapid mass-spectrometric determination of the content of anesthetic agents in blood plasma with the aid of a membrane-separator interface. The interface employs a hydrophobic selective membrane that is capable of separating various anesthetic drugs (including inhalation anesthetic sevofluran, noninhalation anesthetic thiopental, hypnotic propofol, and opioid analgesic fentanyl) from the blood plasma and introducing samples into a mass spectrometer. Analysis of the blood plasma was not accompanied by the memory effect and did not lead to membrane degradation. Results of clinical investigation of the concentration of anesthetics in the blood plasma of patients are presented.

  5. Electrospray mass spectrometric evidence for the occurrence of two major variants in native pig pepsin A.

    PubMed Central

    Green, B N; Jones, A T; Roberts, N B

    1996-01-01

    Native pig pepsin was analysed by negative ion electrospray mass spectrometry in order to rationalize anomalies between the published sequences. Outstanding variations in otherwise identical sequences indicate that amino acid residue 242 is either Asp or Tyr, and in some determinations an additional Ile is inserted at position 230. Mass spectrometric evidence is consistent with the presence, in the native enzyme, of two variants in comparable abundance, with either Asp or Tyr at residue 242. There is no evidence for the additional Ile at position 230. PMID:8546690

  6. Ambient aerodynamic ionization source for remote analyte sampling and mass spectrometric analysis.

    PubMed

    Dixon, R Brent; Sampson, Jason S; Hawkridge, Adam M; Muddiman, David C

    2008-07-01

    The use of aerodynamic devices in ambient ionization source development has become increasingly prevalent in the field of mass spectrometry. In this study, an air ejector has been constructed from inexpensive, commercially available components to incorporate an electrospray ionization emitter within the exhaust jet of the device. This novel aerodynamic device, herein termed remote analyte sampling, transport, and ionization relay (RASTIR) was used to remotely sample neutral species in the ambient and entrain them into an electrospray plume where they were subsequently ionized and detected using a linear ion trap Fourier transform mass spectrometer. Two sets of experiments were performed in the ambient environment to demonstrate the device's utility. The first involved the remote (approximately 1 ft) vacuum collection of pure sample particulates (i.e., dry powder) from a glass slide, entrainment and ionization at the ESI emitter, and mass spectrometric detection. The second experiment involved the capture (vacuum collection) of matrix-assisted laser desorbed proteins followed by entrainment in the ESI emitter plume, multiple charging, and mass spectrometric detection. This approach is in principle a RASTIR-assisted matrix-assisted laser desorption electrospray ionization source (Sampson, J. S.; Hawkridge, A. M.; Muddiman, D. C. J. Am. Soc. Mass Spectrom. 2006, 17, 1712-1716; Rapid Commun. Mass Spectrom. 2007, 21, 1150-1154.). A detailed description of the device construction, operational parameters, and preliminary small molecule and protein data are presented.

  7. Mass spectrometric analysis of tobacco-specific hemoglobin adducts.

    PubMed Central

    Schäffler, G; Betz, C; Richter, E

    1993-01-01

    Hemoglobin adducts of the common metabolite of the tobacco-specific nitrosamine (TSNA) 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB) and of 4-aminobiphenyl (4-ABP) were quantified in blood samples from smokers and nonsmokers to test their suitability for biomonitoring tobacco smoke exposure. Additionally, TSNA adducts were measured in nasal snuff users. Mild alkaline treatment of hemoglobin releases 4-ABP and HPB, which were analyzed in parallel by capillary gas chromatography with electronic impact or negative ion chemical-ionization mass spectrometry (EI- or NICI-GC-MS). Samples of snuff users showed high levels of HPB adducts not correlated with the amount or type of snuff used. HPB concentrations in smokers and nonsmokers, however, were much lower, with no group-specific differences detectable. In contrast, 4-ABP adduct levels were much higher in smokers than in nonsmokers, confirming the significant difference between these two groups reported by others. PMID:8319620

  8. Thermogravimetric-mass spectrometric analysis on combustion of lignocellulosic biomass.

    PubMed

    López-González, D; Fernandez-Lopez, M; Valverde, J L; Sanchez-Silva, L

    2013-09-01

    Combustion characteristics of biomass main components and three lignocellulosic biomass (fir wood, eucalyptus wood and pine bark) were investigated by thermogravimetric analysis coupled with mass spectrometry. The combustion of biomass was divided into two main steps, devolatilization and char oxidation stage. Heating rate effect was also studied. Generally, the higher the heating rate, the higher the decomposition temperature. Furthermore, the weight loss rate decreased due to particle temperature gradients. Combustion kinetics were studied. Models based on reaction order (Oi), nucleation (Ni) and diffusion (Di) achieved the best fitting to the experimental data. Cellulose oxidation presented the highest activation energies. CO, CO2 and H2O were the main components evolved from combustion. Additionally, light hydrocarbons (CH4 and C2H5) were also present. Finally, nitrogen compounds were in a higher proportion than sulfur compounds being released as primary amines and NOx. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Quantitative mass spectrometric analysis of glycoproteins combined with enrichment methods.

    PubMed

    Ahn, Yeong Hee; Kim, Jin Young; Yoo, Jong Shin

    2015-01-01

    Mass spectrometry (MS) has been a core technology for high sensitive and high-throughput analysis of the enriched glycoproteome in aspects of quantitative assays as well as qualitative profiling of glycoproteins. Because it has been widely recognized that aberrant glycosylation in a glycoprotein may involve in progression of a certain disease, the development of efficient analysis tool for the aberrant glycoproteins is very important for deep understanding about pathological function of the glycoprotein and new biomarker development. This review first describes the protein glycosylation-targeting enrichment technologies mainly employing solid-phase extraction methods such as hydrizide-capturing, lectin-specific capturing, and affinity separation techniques based on porous graphitized carbon, hydrophilic interaction chromatography, or immobilized boronic acid. Second, MS-based quantitative analysis strategies coupled with the protein glycosylation-targeting enrichment technologies, by using a label-free MS, stable isotope-labeling, or targeted multiple reaction monitoring (MRM) MS, are summarized with recent published studies.

  10. Imaging Mass Spectrometric Analysis of Neurotransmitters: A Review

    PubMed Central

    Romero-Perez, Gustavo A.; Takei, Shiro; Yao, Ikuko

    2014-01-01

    Imaging mass spectrometry (IMS) is a toolbox of versatile techniques that enable us to investigate analytes in samples at molecular level. In recent years, IMS, and especially matrix-assisted laser desorption/ionisation (MALDI), has been used to visualise a wide range of metabolites in biological samples. Simultaneous visualisation of the spatial distribution of metabolites in a single sample with little tissue disruption can be considered as one important advantage of MALDI over other techniques. However, several technical hurdles including low concentrations and rapid degradation rates of small molecule metabolites, matrix interference of signals and poor ionisation, need to be addressed before MALDI can be considered as a reliable tool for the analysis of metabolites such as neurotransmitters in brain tissues from different sources including humans. In the present review we will briefly describe current MALDI IMS techniques used to study neurotransmitters and discuss their current status, challenges, as well as future prospects. PMID:26819893

  11. Next generation of food allergen quantification using mass spectrometric systems.

    PubMed

    Koeberl, Martina; Clarke, Dean; Lopata, Andreas L

    2014-08-01

    Food allergies are increasing worldwide and becoming a public health concern. Food legislation requires detailed declarations of potential allergens in food products and therefore an increased capability to analyze for the presence of food allergens. Currently, antibody-based methods are mainly utilized to quantify allergens; however, these methods have several disadvantages. Recently, mass spectrometry (MS) techniques have been developed and applied to food allergen analysis. At present, 46 allergens from 11 different food sources have been characterized using different MS approaches and some specific signature peptides have been published. However, quantification of allergens using MS is not routinely employed. This review compares the different aspects of food allergen quantification using advanced MS techniques including multiple reaction monitoring. The latter provides low limits of quantification for multiple allergens in simple or complex food matrices, while being robust and reproducible. This review provides an overview of current approaches to analyze food allergens, with specific focus on MS systems and applications.

  12. Comprehensive mass spectrometric analysis of novel organic semiconductor molecules

    NASA Astrophysics Data System (ADS)

    Prada, Svitlana

    This work presents a comprehensive mass spectrometry (MS) study of novel organic semiconductor molecules including ion mobility/reactivity measurements and trace elemental analysis. The organic molecules investigated here are important semiconductor materials for molecular electronic devices such as Organic Field-Effect Transistors (OFETs) and Light Emitted Diodes (LED). A high-performance orthogonal time-of flight mass spectrometer (TOF-MS) in combination with a matrix assisted laser desorption/ionization (MALDI) source operating at elevated pressure was used to perform MALDI/TOF analyses of pentacene and some of its derivatives with and without an added matrix. The observation of ion-molecule reactions between "cold" analyte ions and neutral analyte molecules in the gas phase has provided some insight into the mechanism of pentacene cluster formation and its functionalized derivatives. Furthermore, some of the matrices employed to assist the desorption/ionization process of these compounds were observed to influence the outcome via ion-molecule reactions of analyte ions and matrix molecules in the gas phase. The stability and reactivity of the compounds and their clusters in the MALDI plume during gas-phase expansion were evaluated; possible structures of the resulting clusters are discussed. The MALDI/TOF technique was also helpful in distinguishing between two isomeric forms of bis-[(triisopropylsilyl)-ethynyl]-pentacene. Furthermore, we reported ion mobility measurements of functionalized pentacene ions with a modified triple quadrupole mass spectrometer fitted with an ion molecule reactor (IMR). The IMR is equipped with a variable axial electrostatic drift field (ADF) and is able to trap ions for a prolong period of time. These capabilities were successfully employed in the measurement of ion mobilities in different modes of the IMR operation. Theoretical modeling of the drift dynamics and the special localization of the large ion packet was successfully

  13. Imaging Mass Spectrometric Analysis of Neurotransmitters: A Review.

    PubMed

    Romero-Perez, Gustavo A; Takei, Shiro; Yao, Ikuko

    2014-01-01

    Imaging mass spectrometry (IMS) is a toolbox of versatile techniques that enable us to investigate analytes in samples at molecular level. In recent years, IMS, and especially matrix-assisted laser desorption/ionisation (MALDI), has been used to visualise a wide range of metabolites in biological samples. Simultaneous visualisation of the spatial distribution of metabolites in a single sample with little tissue disruption can be considered as one important advantage of MALDI over other techniques. However, several technical hurdles including low concentrations and rapid degradation rates of small molecule metabolites, matrix interference of signals and poor ionisation, need to be addressed before MALDI can be considered as a reliable tool for the analysis of metabolites such as neurotransmitters in brain tissues from different sources including humans. In the present review we will briefly describe current MALDI IMS techniques used to study neurotransmitters and discuss their current status, challenges, as well as future prospects.

  14. Capillary electrophoretic and mass spectrometric analysis of a polydisperse fluorosurfactant.

    PubMed

    Al-Jarah, Suhair Yousif; Sjödahl, Johan; Woldegiorgis, Andreas; Emmer, Asa

    2005-02-01

    A fluorosurfactant has been studied using capillary electrophoresis and mass spectrometry. The fluorosurfactant, FC134, can be used as a buffer additive in capillary electrophoresis in order to decrease wall adsorption of proteins and in micellar electrokinetic chromatography. However, it has been discovered that this fluorosurfactant is polydisperse, thus containing substances with different lengths and structures. In this work, the fluorosurfactant sample components were separated by capillary electrophoresis. An uncoated as well as a poly(vinyl alcohol)-coated capillary were used with running electrolytes containing methanol and acetic acid. Following the capillary electrophoretic separation, fractions were collected for further analysis by MALDI-MS. Non-fractionated samples were also analyzed both by MALDI-MS and by ESI-MS.

  15. Mass spectrometric methods for monitoring redox processes in electrochemical cells

    PubMed Central

    Oberacher, Herbert; Pitterl, Florian; Erb, Robert; Plattner, Sabine

    2015-01-01

    Electrochemistry (EC) is a mature scientific discipline aimed to study the movement of electrons in an oxidation–reduction reaction. EC covers techniques that use a measurement of potential, charge, or current to determine the concentration or the chemical reactivity of analytes. The electrical signal is directly converted into chemical information. For in-depth characterization of complex electrochemical reactions involving the formation of diverse intermediates, products and byproducts, EC is usually combined with other analytical techniques, and particularly the hyphenation of EC with mass spectrometry (MS) has found broad applicability. The analysis of gases and volatile intermediates and products formed at electrode surfaces is enabled by differential electrochemical mass spectrometry (DEMS). In DEMS an electrochemical cell is sampled with a membrane interface for electron ionization (EI)-MS. The chemical space amenable to EC/MS (i.e., bioorganic molecules including proteins, peptides, nucleic acids, and drugs) was significantly increased by employing electrospray ionization (ESI)-MS. In the simplest setup, the EC of the ESI process is used to analytical advantage. A limitation of this approach is, however, its inability to precisely control the electrochemical potential at the emitter electrode. Thus, particularly for studying mechanistic aspects of electrochemical processes, the hyphenation of discrete electrochemical cells with ESI-MS was found to be more appropriate. The analytical power of EC/ESI-MS can further be increased by integrating liquid chromatography (LC) as an additional dimension of separation. Chromatographic separation was found to be particularly useful to reduce the complexity of the sample submitted either to the EC cell or to ESI-MS. Thus, both EC/LC/ESI-MS and LC/EC/ESI-MS are common. PMID:24338642

  16. Mass spectrometric methods for monitoring redox processes in electrochemical cells.

    PubMed

    Oberacher, Herbert; Pitterl, Florian; Erb, Robert; Plattner, Sabine

    2015-01-01

    Electrochemistry (EC) is a mature scientific discipline aimed to study the movement of electrons in an oxidation-reduction reaction. EC covers techniques that use a measurement of potential, charge, or current to determine the concentration or the chemical reactivity of analytes. The electrical signal is directly converted into chemical information. For in-depth characterization of complex electrochemical reactions involving the formation of diverse intermediates, products and byproducts, EC is usually combined with other analytical techniques, and particularly the hyphenation of EC with mass spectrometry (MS) has found broad applicability. The analysis of gases and volatile intermediates and products formed at electrode surfaces is enabled by differential electrochemical mass spectrometry (DEMS). In DEMS an electrochemical cell is sampled with a membrane interface for electron ionization (EI)-MS. The chemical space amenable to EC/MS (i.e., bioorganic molecules including proteins, peptides, nucleic acids, and drugs) was significantly increased by employing electrospray ionization (ESI)-MS. In the simplest setup, the EC of the ESI process is used to analytical advantage. A limitation of this approach is, however, its inability to precisely control the electrochemical potential at the emitter electrode. Thus, particularly for studying mechanistic aspects of electrochemical processes, the hyphenation of discrete electrochemical cells with ESI-MS was found to be more appropriate. The analytical power of EC/ESI-MS can further be increased by integrating liquid chromatography (LC) as an additional dimension of separation. Chromatographic separation was found to be particularly useful to reduce the complexity of the sample submitted either to the EC cell or to ESI-MS. Thus, both EC/LC/ESI-MS and LC/EC/ESI-MS are common.

  17. Mass spectrometric characterization of oligomers in Pseudomonas aeruginosa azurin solutions

    PubMed Central

    Sokolová, Lucie; Williamson, Heather; Sýkora, Jan; Hof, Martin; Gray, Harry B.; Brutschy, Bernd; Vlček, Antonín

    2011-01-01

    We have employed laser induced liquid bead ion desorption mass spectroscopy (LILBID MS) to study the solution behavior of Pseudomonas aeruginosa azurin as well as two mutants and corresponding Re-labeled derivatives containing a Re(CO)3(4,7-dimethyl-1,10-phenanthroline) chromophore appended to a surface histidine. LILBID spectra show broad oligomer distributions whose particular patterns depend on the solution composition (pure H2O, 20–30 mM NaCl, 20 and 50 mM NaPi or NH4Pi at pH = 7). The distribution maximum shifts to smaller oligomers upon decreasing the azurin concentration and increasing the buffer concentration. Oligomerization is less extensive for native azurin than its mutants. The oligomerization propensities of unlabeled and Re-labeled proteins are generally comparable, only Re126 shows some preference for the dimer that persists even in highly diluted solutions. Peak shifts to higher masses and broadening in 20–50 mM NaPi confirm strong azurin association with buffer ions and solvation. We have found that LILBID MS reveals the solution behavior of weakly bound nonspecific oligomers, clearly distinguishing individual components of the oligomer distribution. Independently, average data on oligomerization and the dependence on solution composition were obtained by time-resolved anisotropy of the Re-label photoluminescence that confirmed relatively long rotation correlation times, 6–30 ns, depending on Re-azurin and solution composition. Labeling proteins with Re-chromophores that have long-lived phosphorescence extends the timescale of anisotropy measurements to hundreds of ns, thereby opening the way for investigations of large oligomers with long rotation times. PMID:21452827

  18. Mass spectrometric characterization of the Rosetta Spacecraft contamination

    NASA Astrophysics Data System (ADS)

    Bieler, A.; Altwegg, K.; Balsiger, H.; Berthelier, J.-J.; Calmonte, U.; Combi, M.; De Keyser, J.; Fiethe, B.; Fuselier, S. A.; Gasc, S.; Gombosi, T.; Hansen, K. C.; Hässig, M.; Korth, A.; Le Roy, L.; Mall, U.; Rème, H.; Rubin, M.; Sémon, T.; Tenishev, V.; Tzou, C.-Y.; Waite, J. H.; Wurz, P.

    2016-09-01

    Mass spectrometers are valuable tools for the in situ characterization of gaseous exo- and atmospheres and have been operated at various bodies in space. Typical measurements derive the elemental composition, relative abundances, and isotopic ratios of the examined environment. To sample tenuous gas environments around comets, icy moons, and the exosphere of Mercury, efficient instrument designs with high sensitivity are mandatory while the contamination by the spacecraft and the sensor itself should be kept as low as possible. With the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA), designed to characterize the coma of comet 67P/Churyumov-Gerasimenko, we were able to quantify the effects of spacecraft contamination on such measurements. By means of 3D computational modeling of a helium leak in the thruster pressurization tubing that was detected during the cruise phase we examine the physics involved leading to the measurements of contamination. 3 types of contamination can be distinguished: i) Compounds from the decomposition of the spacecraft material. ii) Contamination from thruster firing during maneuvers. iii) Adsorption and desorption of the sampled environment on and from the spacecraft. We show that even after more than ten years in space the effects of i) are still detectable by ROSINA and impose an important constraint on the lower limit of gas number densities one can examine by means of mass spectrometry. Effects from ii) act on much shorter time scales and can be avoided or minimized by proper mission planning and data analysis afterwards. iii) is the most difficult effect to quantify as it changes over time and finally carries the fingerprint of the sampled environment which makes prior calibration not possible.

  19. A review on the mass spectrometric studies of americium: Present status and future perspective.

    PubMed

    Aggarwal, Suresh Kumar

    2016-05-06

    The manuscript reviews the various mass spectrometric techniques for analysis and chemical studies of Americium. These methods include thermal ionization mass spectrometry (TIMS), and inductively coupled plasma source mass spectrometry (ICPMS) for the determination of Am isotope ratios and concentration in nuclear fuel samples of interest in nuclear technology, and in complex biological and environmental samples. Ultra-sensitive mass spectrometric techniques of resonance-ionization mass spectrometry (RIMS), and accelerator-based mass spectrometry (AMS) are also discussed. The novel applications of electrospray ionization mass spectrometry (ESIMS) to understand the solution chemistry of Am and other actinides are presented. These studies are important in view of the world-wide efforts to develop novel complexing agents to separate lanthanides and minor actinides (Am, Np, and Cm) for partitioning and transmutation of minor actinides from the point of view of nuclear waste management. These mass spectrometry experiments are also of great interest to examine the covalent character of actinides with increasing atomic number. Studies on gas-phase chemistry of Am and its oxides with Knudsen effusion mass spectrometry (KEMS), Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS), and laser-based experiments with reflectron time-of-flight mass spectrometer (R-ToF) are highlighted. These studies are important to understand the fundamental chemistry of 5f electrons in actinides. Requirement of certified isotopic reference materials of Am to improve the accuracy of experimental nuclear data (e.g., the half-life of (243) Am) is emphasized. © 2016 Wiley Periodicals, Inc. Mass Spec Rev.

  20. Mass spectrometric studies of fast pyrolysis of cellulose.

    PubMed

    Degenstein, John C; Hurt, Matt; Murria, Priya; Easton, McKay; Choudhari, Harshavardhan; Yang, Linan; Riedeman, James; Carlsen, Mark S; Nash, John J; Agrawal, Rakesh; Delgass, W Nicholas; Ribeiro, Fabio H; Kenttämaa, Hilkka I

    2015-01-01

    A fast pyrolysis probe/linear quadrupole ion trap mass spectrometer combination was used to study the primary fast pyrolysis products (those that first leave the hot pyrolysis surface) of cellulose, cellobiose, cellotriose, cellotetraose, cellopentaose, and cellohexaose, as well as of cellobiosan, cellotriosan, and cellopentosan, at 600°C. Similar products with different branching ratios were found for the oligosaccharides and cellulose, as reported previously. However, identical products (with the exception of two) with similar branching ratios were measured for cellotriosan (and cellopentosan) and cellulose. This result demonstrates that cellotriosan is an excellent small-molecule surrogate for studies of the fast pyrolysis of cellulose and also that most fast pyrolysis products of cellulose do not originate from the reducing end. Based on several observations, the fast pyrolysis of cellulose is suggested to initiate predominantly via two competing processes: the formation of anhydro-oligosaccharides, such as cellobiosan, cellotriosan, and cellopentosan (major route), and the elimination of glycolaldehyde (or isomeric) units from the reducing end of oligosaccharides formed from cellulose during fast pyrolysis.

  1. A mass spectrometric-derived cell surface protein atlas.

    PubMed

    Bausch-Fluck, Damaris; Hofmann, Andreas; Bock, Thomas; Frei, Andreas P; Cerciello, Ferdinando; Jacobs, Andrea; Moest, Hansjoerg; Omasits, Ulrich; Gundry, Rebekah L; Yoon, Charles; Schiess, Ralph; Schmidt, Alexander; Mirkowska, Paulina; Härtlová, Anetta; Van Eyk, Jennifer E; Bourquin, Jean-Pierre; Aebersold, Ruedi; Boheler, Kenneth R; Zandstra, Peter; Wollscheid, Bernd

    2015-01-01

    Cell surface proteins are major targets of biomedical research due to their utility as cellular markers and their extracellular accessibility for pharmacological intervention. However, information about the cell surface protein repertoire (the surfaceome) of individual cells is only sparsely available. Here, we applied the Cell Surface Capture (CSC) technology to 41 human and 31 mouse cell types to generate a mass-spectrometry derived Cell Surface Protein Atlas (CSPA) providing cellular surfaceome snapshots at high resolution. The CSPA is presented in form of an easy-to-navigate interactive database, a downloadable data matrix and with tools for targeted surfaceome rediscovery (http://wlab.ethz.ch/cspa). The cellular surfaceome snapshots of different cell types, including cancer cells, resulted in a combined dataset of 1492 human and 1296 mouse cell surface glycoproteins, providing experimental evidence for their cell surface expression on different cell types, including 136 G-protein coupled receptors and 75 membrane receptor tyrosine-protein kinases. Integrated analysis of the CSPA reveals that the concerted biological function of individual cell types is mainly guided by quantitative rather than qualitative surfaceome differences. The CSPA will be useful for the evaluation of drug targets, for the improved classification of cell types and for a better understanding of the surfaceome and its concerted biological functions in complex signaling microenvironments.

  2. A Mass Spectrometric-Derived Cell Surface Protein Atlas

    PubMed Central

    Bausch-Fluck, Damaris; Hofmann, Andreas; Bock, Thomas; Frei, Andreas P.; Cerciello, Ferdinando; Jacobs, Andrea; Moest, Hansjoerg; Omasits, Ulrich; Gundry, Rebekah L.; Yoon, Charles; Schiess, Ralph; Schmidt, Alexander; Mirkowska, Paulina; Härtlová, Anetta; Van Eyk, Jennifer E.; Bourquin, Jean-Pierre; Aebersold, Ruedi; Boheler, Kenneth R.; Zandstra, Peter; Wollscheid, Bernd

    2015-01-01

    Cell surface proteins are major targets of biomedical research due to their utility as cellular markers and their extracellular accessibility for pharmacological intervention. However, information about the cell surface protein repertoire (the surfaceome) of individual cells is only sparsely available. Here, we applied the Cell Surface Capture (CSC) technology to 41 human and 31 mouse cell types to generate a mass-spectrometry derived Cell Surface Protein Atlas (CSPA) providing cellular surfaceome snapshots at high resolution. The CSPA is presented in form of an easy-to-navigate interactive database, a downloadable data matrix and with tools for targeted surfaceome rediscovery (http://wlab.ethz.ch/cspa). The cellular surfaceome snapshots of different cell types, including cancer cells, resulted in a combined dataset of 1492 human and 1296 mouse cell surface glycoproteins, providing experimental evidence for their cell surface expression on different cell types, including 136 G-protein coupled receptors and 75 membrane receptor tyrosine-protein kinases. Integrated analysis of the CSPA reveals that the concerted biological function of individual cell types is mainly guided by quantitative rather than qualitative surfaceome differences. The CSPA will be useful for the evaluation of drug targets, for the improved classification of cell types and for a better understanding of the surfaceome and its concerted biological functions in complex signaling microenvironments. PMID:25894527

  3. High-throughput mass spectrometric cytochrome P450 inhibition screening.

    PubMed

    Lim, Kheng B; Ozbal, Can C; Kassel, Daniel B

    2013-01-01

    We describe here a high-throughput assay to support rapid evaluation of drug discovery compounds for possible drug-drug interaction (DDI). Each compound is evaluated for its DDI potential by incubating over a range of eight concentrations and against a panel of six cytochrome P450 (CYP) enzymes: 1A2, 2C8, 2C9, 2C19, 2D6, and 3A4. The method utilizes automated liquid handling for sample preparation, and online solid-phase extraction/tandem mass spectrometry (SPE/MS/MS) for sample analyses. The system is capable of generating two 96-well assay plates in 30 min, and completes the data acquisition and analysis of both plates in about 30 min. Many laboratories that perform the CYP inhibition screening automate only part of the processes leaving a throughput bottleneck within the workflow. The protocols described in this chapter are aimed to streamline the entire process from assay to data acquisition and processing by incorporating automation and utilizing high-precision instrument to maximize throughput and minimize bottleneck.

  4. Mass spectrometric studies of fast pyrolysis of cellulose

    SciTech Connect

    Degenstein, John; Hurt, Matt; Murria, Priya; Easton, McKay; Choudhari, Harshavardhan; Yang, Linan; Riedeman, James; Carlsen, Mark; Nash, John; Agrawal, Rakesh; Delgass, W.; Ribeiro, Fabio; Kenttämaa, Hilkka

    2015-01-01

    A fast pyrolysis probe/linear quadrupole ion trap mass spectrometer combination was used to study the primary fast pyrolysis products (those that first leave the hot pyrolysis surface) of cellulose, cellobiose, cellotriose, cellotetraose, cellopentaose, and cellohexaose, as well as of cellobiosan, cellotriosan, and cellopentosan, at 600°C. Similar products with different branching ratios were found for the oligosaccharides and cellulose, as reported previously. However, identical products (with the exception of two) with similar branching ratios were measured for cellotriosan (and cellopentosan) and cellulose. This result demonstrates that cellotriosan is an excellent small-molecule surrogate for studies of the fast pyrolysis of cellulose and also that most fast pyrolysis products of cellulose do not originate from the reducing end. Based on several observations, the fast pyrolysis of cellulose is suggested to initiate predominantly via two competing processes: the formation of anhydro-oligosaccharides, such as cellobiosan, cellotriosan, and cellopentosan (major route), and the elimination of glycolaldehyde (or isomeric) units from the reducing end of oligosaccharides formed from cellulose during fast pyrolysis.

  5. Vacuum ultraviolet photoionization mass spectrometric study of cyclohexene.

    PubMed

    Chen, Jun; Cao, Maoqi; Wei, Bin; Ding, Mengmeng; Shan, Xiaobin; Liu, Fuyi; Sheng, Liusi

    2016-02-01

    In this work, photoionization and dissociation of cyclohexene have been studied by means of coupling a reflectron time-of-flight mass spectrometer with the tunable vacuum ultraviolet (VUV) synchrotron radiation. The adiabatic ionization energy of cyclohexene as well as the appearance energies of its fragment ions C6 H9 (+) , C6 H7 (+) , C5 H7 (+) , C5 H5 (+) , C4 H6 (+) , C4 H5 (+) , C3 H5 (+) and C3 H3 (+) were derived from the onset of the photoionization efficiency (PIE) curves. The optimized structures for the transition states and intermediates on the ground state potential energy surfaces related to photodissociation of cyclohexene were characterized at the ωB97X-D/6-31+g(d,p) level. The coupled cluster method, CCSD(T)/cc-pVTZ, was employed to calculate the corresponding energies with the zero-point energy corrections by the ωB97X-D/6-31+g(d,p) approach. Combining experimental and theoretical results, possible formation pathways of the fragment ions were proposed and discussed in detail. The retro-Cope rearrangement was found to play a crucial role in the formation of C4 H6 (+) , C4 H5 (+) and C3 H5 (+) . Intramolecular hydrogen migrations were observed as dominant processes in most of the fragmentation pathways of cyclohexene. The present research provides a clear picture of the photoionization and dissociation processes of cyclohexene in the 8- to 15.5-eV photon energy region. Copyright © 2016 John Wiley & Sons, Ltd.

  6. Electrospray ionization tandem mass spectrometric and electron impact mass spectrometric characterization of mycosporine-like amino acids.

    PubMed

    Whitehead, Kenia; Hedges, John I

    2003-01-01

    Positive-ion mass spectral fragmentations of seven mycosporine-like amino acids (MAAs) are reported and discussed. The MAAs studied are small compounds composed of a cycloheximine ring substituted with amino acid or amino alcohol units. Techniques used include electron impact (EI) and electrospray ionization (ESI) with tandem mass spectrometry (MS/MS). ESI-MS/MS showed unusual small radical losses, generally resulting from the loss of a methyl group with the exception of shinorine and porphyra for which the initial losses were 30 and 44 Da, respectively. As expected from structural similarities, porphyra, shinorine and palythinol displayed similar fragmentation patterns, while palythenic acid and palythene fragmented in a similar manner. Overall, the ESI-MS/MS fragmentations at m/z <200 exhibited a distinctive pattern for all seven MAAs with characteristic ions at m/z 137, 168, 186, and 197 or 199. Several ions were observed for each of the MAAs analyzed, and together provide a useful and potentially diagnostic pattern for identification of MAAs and as an aid in structure elucidation of novel MAAs. For GC/EI-MS analysis, trimethylsilyl (TMS) derivatives were made. The EI-MS fragmentation patterns of TMS-MAAs showed many features typical of TMS-derivatized alpha-amines. The precursor TMS-MAA ion was not detected, but a [M-90](+ radical) ion was the highest-mass intense peak observed for palythine, palythinol and shinorine, while palythene gave a [M-116](+ radical) ion. Besides determining the number of acidic hydrogens, EI-MS of TMS-derivatized MAAs will aid in structure elucidation of novel MAAs. Copyright 2003 John Wiley & Sons, Ltd.

  7. Desorption chemical ionization and fast atom bombardment mass spectrometric studies of the glucuronide metabolites of doxylamine.

    PubMed

    Lay, J O; Korfmacher, W A; Miller, D W; Siitonen, P; Holder, C L; Gosnell, A B

    1986-11-01

    Three glucuronide metabolites of doxylamine succinate were collected in a single fraction using high-performance liquid chromatography (HPLC) from the urine of dosed male Fischer 344 rats. The metabolites were then separated using an additional HPLC step into fractions containing predominantly a single glucuronide metabolite. Analysis of the metabolites by methane and ammonia desorption chemical ionization, with and without derivatization, revealed fragment ions suggestive of a hydroxylated doxylamine moiety. Identification of the metabolites as glucuronides of doxylamine, desmethyldoxylamine and didesmethyldoxylamine was accomplished, based on determination of the molecular weight and exact mass of each metabolite using fast atom bombardment (FAB) ionization. This assignment was confirmed by the fragmentation observed in FAB mass spectrometric and tandem mass spectrometric experiments. Para-substitution of the glucuronide on the phenyl moiety was observed by 500-MHz nuclear magnetic resonance (NMR) spectrometry. A fraction containing all three glucuronide metabolites, after a single stage of HPLC separation, was also analysed by FAB mass spectrometry, and the proton- and potassium-containing quasimolecular ions for all three metabolites were observed.

  8. On-line overpressure thin-layer chromatographic separation and electrospray mass spectrometric detection of glycolipids.

    PubMed

    Chai, Wengang; Leteux, Christine; Lawson, Alexander M; Stoll, Mark S

    2003-01-01

    On-line thin-layer chromatographic separation and electrospray mass spectrometry (TLC/ESI-MS) has been accomplished by direct linking of a commercial overpressure TLC instrument, OPLC 50, and a Q-TOF mass spectrometer. Mass spectrometric detection sensitivity and chromatographic resolution achieved by this configuration were assessed using acidic glycolipids as examples. Under the optimized conditions, a sensitivity of 5 pmol of glycosphingolipid was readily demonstrated for TLC/ESI-MS and 20 pmol for TLC/ESI-MS/MS production scanning to derive the saccharide sequence and long chain base/fatty acid composition of the ceramide. Initial preconditioning of TLC plates is necessary to achieve high sensitivity detection by reducing chemical background noise. Plates can be used repeatedly (at least 10 times) for analysis, although this may result in a minor reduction in TLC resolution. Following solvent development, separated components on the TLC plates can be detected in the conventional way by nondestructive staining or UV absorption or fluorescence and can be stored for on-line TLC/ESI-MS analysis at a later stage without reduction in mass spectrometric detection sensitivity and chromatographic resolution. Aspects for further improvement of OPLC instrumentation include use of narrower TLC plate dimensions and refined design of the eluate exit system.

  9. Mass spectrometric determination of gases in individual fluid inclusions in natural minerals

    SciTech Connect

    Barker, C.; Smith, M.P.

    1986-06-01

    Fluid inclusions in minerals provide a source of geologically significant fluids. A new computerized mass spectrometric technique for analyzing volatiles in individual inclusions has been developed. The inclusions are opened by decrepitation in vacuum, and the computer recognizes the abrupt rise in pressure and controls the mass spectrometer. This scans continuously from 1 to 65 amu every 25 ms, which is within the time constraints of a bursting inclusion. The peak height for each mass in each spectrum is measured and stored along with the background data. Data are reduced after analysis. Each mass number is assigned its own attenuation factor by the computer in a preliminary analysis. This permits the determination of trace components down to 1 part in 10,000. With this system it is possible to analyze up to 225 inclusions in 1 h using a 10-mg sample of quartz, calcite, plagioclase, pyroxene, galena, or other mineral.

  10. Tandem mass spectrometric fragmentation patterns of known and new steviol glycosides with structure proposals.

    PubMed

    Zimmermann, Benno F

    2011-06-15

    Stevia rebaudiana contains several steviol glycosides that have a sweet flavor. They are up to 450 times sweeter than sucrose, but some have an undesirable aftertaste. Up to 2010, ten different steviol glycosides have been described from the leaves or purified extracts of S. rebaudiana. In this paper, the tandem mass spectrometric fragmentation patterns of these ten compounds are compiled, along with a scheme for structural elucidation. This scheme is then applied to 12 steviol glycosides that have not yet been described. The proposed structures of five steviol glycosides have been confirmed by other authors. Copyright © 2011 John Wiley & Sons, Ltd.

  11. Developments in the application of gas chromatography with atomic emission (plus mass spectrometric) detection.

    PubMed

    van Stee, L L P; Brinkman, U A Th

    2008-04-04

    Capillary gas chromatography with atomic emission detection is a highly element-selective and sensitive detection technique for many non-metal as well as metallic elements. A 3-5 order of magnitude element/carbon selectivity, compound-independent calibration and the possibility to calculate (partial) molecular formulae are some of the attractive features of the technique. In the present review, the emphasis is on real-life applications for non-metals such as sulphur, phosphorus, nitrogen and the halogens, and on the potential of combined atomic emission/mass spectrometric detection.

  12. Mass Spectrometric Detection of Bacterial Protein Toxins and Their Enzymatic Activity

    PubMed Central

    Kalb, Suzanne R.; Boyer, Anne E.; Barr, John R.

    2015-01-01

    Mass spectrometry has recently become a powerful technique for bacterial identification. Mass spectrometry approaches generally rely upon introduction of the bacteria into a matrix-assisted laser-desorption time-of-flight (MALDI-TOF) mass spectrometer with mass spectrometric recognition of proteins specific to that organism that form a reliable fingerprint. With some bacteria, such as Bacillus anthracis and Clostridium botulinum, the health threat posed by these organisms is not the organism itself, but rather the protein toxins produced by the organisms. One such example is botulinum neurotoxin (BoNT), a potent neurotoxin produced by C. botulinum. There are seven known serotypes of BoNT, A–G, and many of the serotypes can be further differentiated into toxin variants, which are up to 99.9% identical in some cases. Mass spectrometric proteomic techniques have been established to differentiate the serotype or toxin variant of BoNT produced by varied strains of C. botulinum. Detection of potent biological toxins requires high analytical sensitivity and mass spectrometry based methods have been developed to determine the enzymatic activity of BoNT and the anthrax lethal toxins produced by B. anthracis. This enzymatic activity, unique for each toxin, is assessed with detection of the toxin-induced cleavage of strategically designed peptide substrates by MALDI-TOF mass spectrometry offering unparalleled specificity. Furthermore, activity assays allow for the assessment of the biological activity of a toxin and its potential health risk. Such methods have become important diagnostics for botulism and anthrax. Here, we review mass spectrometry based methods for the enzymatic activity of BoNT and the anthrax lethal factor toxin. PMID:26404376

  13. Mass Spectrometric Detection of Bacterial Protein Toxins and Their Enzymatic Activity.

    PubMed

    Kalb, Suzanne R; Boyer, Anne E; Barr, John R

    2015-08-31

    Mass spectrometry has recently become a powerful technique for bacterial identification. Mass spectrometry approaches generally rely upon introduction of the bacteria into a matrix-assisted laser-desorption time-of-flight (MALDI-TOF) mass spectrometer with mass spectrometric recognition of proteins specific to that organism that form a reliable fingerprint. With some bacteria, such as Bacillus anthracis and Clostridium botulinum, the health threat posed by these organisms is not the organism itself, but rather the protein toxins produced by the organisms. One such example is botulinum neurotoxin (BoNT), a potent neurotoxin produced by C. botulinum. There are seven known serotypes of BoNT, A-G, and many of the serotypes can be further differentiated into toxin variants, which are up to 99.9% identical in some cases. Mass spectrometric proteomic techniques have been established to differentiate the serotype or toxin variant of BoNT produced by varied strains of C. botulinum. Detection of potent biological toxins requires high analytical sensitivity and mass spectrometry based methods have been developed to determine the enzymatic activity of BoNT and the anthrax lethal toxins produced by B. anthracis. This enzymatic activity, unique for each toxin, is assessed with detection of the toxin-induced cleavage of strategically designed peptide substrates by MALDI-TOF mass spectrometry offering unparalleled specificity. Furthermore, activity assays allow for the assessment of the biological activity of a toxin and its potential health risk. Such methods have become important diagnostics for botulism and anthrax. Here, we review mass spectrometry based methods for the enzymatic activity of BoNT and the anthrax lethal factor toxin.

  14. Parallel Detection of Intrinsic Fluorescence from Peptides and Proteins for Quantification During Mass Spectrometric Analysis

    PubMed Central

    Russell, Jason D.; Hilger, Ryan T.; Ladror, Daniel T.; Tervo, Mark A.; Scalf, Mark; Shortreed, Michael R.; Coon, Joshua J.

    2011-01-01

    Direct mass spectrometric quantification of peptides and proteins is compromised by the wide variabilities in ionization efficiency which are hallmarks of both the MALDI and ESI ionization techniques. We describe here the implementation of a fluorescence detection system for measurement of the UV-excited intrinsic fluorescence (UV-IF) from peptides and proteins just prior to their exit and electrospray ionization from an ESI capillary. The fluorescence signal provides a quantifiable measure of the amount of the protein or peptide present, while direct or tandem mass spectrometric analysis (MS/MS) on the ESI-generated ions provides information on identity. We fabricated an inexpensive, modular, fluorescence excitation and detection device utilizing an ultraviolet light-emitting diode for excitation in a ~300 nL fluorescence detection cell integrated into the fused-silica separation column. The fluorescence signal was linear over 3 orders of magnitude with on-column limits of detection in the low femtomole range. Chromatographically separated intact proteins analyzed using UV-IF prior to top-down mass spectrometry demonstrated sensitive detection of proteins as large as 77 kDa. PMID:21314137

  15. Assessment of current mass spectrometric workflows for the quantification of low abundant proteins and phosphorylation sites

    PubMed Central

    Bauer, Manuel; Ahrné, Erik; Baron, Anna P.; Glatter, Timo; Fava, Luca L.; Santamaria, Anna; Nigg, Erich A.; Schmidt, Alexander

    2015-01-01

    The data described here provide a systematic performance evaluation of popular data-dependent (DDA) and independent (DIA) mass spectrometric (MS) workflows currently used in quantitative proteomics. We assessed the limits of identification, quantification and detection for each method by analyzing a dilution series of 20 unmodified and 10 phosphorylated synthetic heavy labeled reference peptides, respectively, covering six orders of magnitude in peptide concentration with and without a complex human cell digest background. We found that all methods performed very similarly in the absence of background proteins, however, when analyzing whole cell lysates, targeted methods were at least 5–10 times more sensitive than directed or DDA methods. In particular, higher stage fragmentation (MS3) of the neutral loss peak using a linear ion trap increased dynamic quantification range of some phosphopeptides up to 100-fold. We illustrate the power of this targeted MS3 approach for phosphopeptide monitoring by successfully quantifying 9 phosphorylation sites of the kinetochore and spindle assembly checkpoint component Mad1 over different cell cycle states from non-enriched pull-down samples. The data are associated to the research article ‘Evaluation of data-dependent and data-independent mass spectrometric workflows for sensitive quantification of proteins and phosphorylation sites׳ (Bauer et al., 2014) [1]. The mass spectrometry and the analysis dataset have been deposited to the ProteomeXchange Consortium (http://proteomecentral.proteomexchange.org) via the PRIDE partner repository with the dataset identifier PXD000964. PMID:26550600

  16. GNU polyxmass: a software framework for mass spectrometric simulations of linear (bio-)polymeric analytes

    PubMed Central

    Rusconi, Filippo

    2006-01-01

    Background Nowadays, a variety of (bio-)polymers can be analyzed by mass spectrometry. The detailed interpretation of the spectra requires a huge number of "hypothesis cycles", comprising the following three actions 1) put forth a structural hypothesis, 2) test it, 3) (in)validate it. This time-consuming and painstaking data scrutiny is alleviated by using specialized software tools. However, all the software tools available to date are polymer chemistry-specific. This imposes a heavy overhead to researchers who do mass spectrometry on a variety of (bio-)polymers, as each polymer type will require a different software tool to perform data simulations and analyses. We developed a software to address the lack of an integrated software framework able to deal with different polymer chemistries. Results The GNU polyxmass software framework performs common (bio-)chemical simulations–along with simultaneous mass spectrometric calculations–for any kind of linear bio-polymeric analyte (DNA, RNA, saccharides or proteins). The framework is organized into three modules, all accessible from one single binary program. The modules let the user to 1) define brand new polymer chemistries, 2) perform quick mass calculations using a desktop calculator paradigm, 3) graphically edit polymer sequences and perform (bio-)chemical/mass spectrometric simulations. Any aspect of the mass calculations, polymer chemistry reactions or graphical polymer sequence editing is configurable. Conclusion The scientist who uses mass spectrometry to characterize (bio-)polymeric analytes of different chemistries is provided with a single software framework for his data prediction/analysis needs, whatever the polymer chemistry being involved. PMID:16643644

  17. Proteogenomics meets cancer immunology: mass spectrometric discovery and analysis of neoantigens.

    PubMed

    Polyakova, Anna; Kuznetsova, Ksenia; Moshkovskii, Sergei

    2015-01-01

    Cancer proteogenomics is an emerging field that aims to identify and quantify protein sequence changes associated with the cancer genome. Besides being involved in cancer development and progression, such protein variants may serve as neoantigens, which provide the T-cell response against tumors. Mass spectrometry-based proteogenomics may be a promising tool for finding neoantigens in individual specimens. It is partly based on a technical background accumulated from mass spectrometric studies of peptide ligands of major histocompatibility complex proteins. Examples of the use of mass spectrometry in neoantigen identification are reviewed in this article. Some experimental workflows are discussed, which may use shotgun and targeted proteomics for translational human studies of neoepitopes, such as cancer vaccine development and checkpoint therapy response prediction.

  18. Mass-spectrometric determination of trace elements in aqueous media without preconcentration

    SciTech Connect

    Foss, Gordon Oluf

    1981-10-01

    Feasibility of using a low pressure glow discharge as an ion source for the mass spectrometric determination of trace elements in aqueous media was investigated. A cryogenically cooled hollow cathode ion source was developed to analyze aqueous samples without external preconcentration. Aqueous solutions containing seventy elements were analyzed and the detection limits, sensitivity factors, and linear regression correlation coefficients were determined. A standard test solution of trace elements in water was analyzed and the concentrations of trace elements were calculated using the sensitivity factors determined previously. The results compared favorably within the error limits predicted by the semiquantitative survey methods used. Tap water and natural lake water samples were examined and minimal interference effects due to organic compounds and biological compounds were noted. A research ion optical system (RIOS) was developed as a flexible mass analyzer for the development of new ion sources. The RIOS is a double focussing mass analyzer designed utilizing the Mattauch-Herzog geometry with externally adjustable slit assemblies.

  19. Chromatographic and mass spectrometric fingerprinting analyses of Angelica sinensis (Oliv.) Diels-derived dietary supplements.

    PubMed

    Zhao, Yang; Sun, Jianghao; Yu, Liangli Lucy; Chen, Pei

    2013-05-01

    Angelica sinensis (Oliv.) Diels ("Danggui" in Chinese) is one of the most commonly used traditional Chinese medicines. It has been used to invigorate blood circulation for the treatment of anemia, hypertension, chronic bronchitis, asthma, rheumatism, and cardiovascular diseases. There are a number of A. sinensis-derived dietary supplements in the US markets. However, no study have been conducted to investigate the quality of these dietary supplements. In this paper, high-performance liquid chromatographic and flow-injection mass spectrometric fingerprints were both evaluated to assess the consistency of A. sinensis-derived dietary supplements. Similarity analysis was carried out on the high-performance liquid chromatographic (HPLC) fingerprints. Meanwhile, principal component analysis (PCA) was performed on the data obtained from flow-injection mass spectrometric (FIMS) fingerprints, which can analyze each sample in 2 min, compared with 30 min required for the chromatographic fingerprint. Both methods show significant chemical differences between samples that may be due to differences in growing locations, growing conditions, harvesting times, and/or botanical processing. The loading plots obtained from PCA singled out the discriminatory ions that were responsible for chemical differences of A. sinensis-derived dietary supplements.

  20. The Bremen mass spectrometric facility for the measurement of helium isotopes, neon, and tritium in water.

    PubMed

    Sültenfuss, Jürgen; Roether, Wolfgang; Rhein, Monika

    2009-06-01

    We describe the mass spectrometric facility for measuring helium isotopes, neon, and tritium that has been operative at this institute since 1989, and also the sampling and sample preparation steps that precede the mass spectrometric analysis. For water samples in a near-equilibrium with atmospheric air, the facility achieves precision for (3)He/(4)He ratios of+/-0.4% or better, and+/-0.8 % or better for helium and neon concentrations. Tritium precision is typically+/-3 % and the detection limit 10 mTU ( approximately 1.2.10(-3) Bq/kg of pure water). Sample throughputs can reach some thousands per year. These achievements are enabled, among other features, by automation of the measurement procedure and by elaborate calibration, assisted by continual development in detail. To date, we have measured more than 15,000 samples for tritium and 23,000 for helium isotopes and neon, mostly in the context of oceanographic and hydrologic work. Some results of such work are outlined. Even when atmospheric tritium concentrations have become rather uniform, tritium provides water ages if (3)He data are taken concurrently. The technique can resolve tritium concentrations in waters of the pre-nuclear era.

  1. MALDI mass spectrometric imaging meets "omics": recent advances in the fruitful marriage.

    PubMed

    Crecelius, A C; Schubert, U S; von Eggeling, F

    2015-09-07

    Matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI MSI) is a method that allows the investigation of the molecular content of surfaces, in particular, tissues, within its morphological context. The applications of MALDI MSI in the field of large-scale mass spectrometric studies, which are typically denoted by the suffix "omics", are steadily increasing. This is because, on the one hand, technical advances regarding sample collection and preparation, matrix application, instrumentation, and data processing have enhanced the molecular specificity and sensitivity of MALDI MSI; on the other hand, the focus of the "omics" community has moved from establishing an inventory of certain compound classes to exploring their spatial distribution to gain novel insights. Thus, the aim of this mini-review is twofold, to display the state-of-the-art in terms of technical aspects in MALDI MSI and to highlight selected applications in the last two years, which either have significantly advanced a certain "omics" field or have introduced a new one through pioneering efforts.

  2. A Mass Spectrometric Assay for Analysis of Haptoglobin Fucosylation in Pancreatic Cancer

    PubMed Central

    Lin, Zhenxin; Simeone, Diane M.; Anderson, Michelle A.; Brand, Randall E.; Xie, Xiaolei; Shedden, Kerby A.; Ruffin, Mack T.; Lubman, David M.

    2011-01-01

    A mass spectrometric method was developed to elucidate the N-glycan structures of serum glycoproteins and utilize fucosylated glycans as potential markers for pancreatic cancer. This assay was applied to haptoglobin in human serum where N-glycans derived from the serum of 16 pancreatic cancer patients were compared with those from 15 individuals with benign conditions (5 normals, 5 chronic pancreatitis, and 5 type II diabetes). This assay used only 10uL of serum where haptoglobin was extracted using a monoclonal antibody and quantitative permethylation was performed on desialylated N-glycans followed by MALDI-QIT-TOF MS analysis. Eight desialylated N-glycan structures of haptoglobin were identified where a bifucosylated tri-antennary structure was reported for the first time in pancreatic cancer samples. Both core and antennary fucosylation were elevated in pancreatic cancer samples compared to samples from benign conditions. Fucosylation degree indices were calculated and show a significant difference between pancreatic cancer patients of all stages and the benign conditions analyzed. This study demonstrates that a serum assay based on haptoglobin fucosylation patterns using mass spectrometric analysis may serve as a novel method for the diagnosis of pancreatic cancer. PMID:21417406

  3. Identification of volatiles by headspace gas chromatography with simultaneous flame ionization and mass spectrometric detection.

    PubMed

    Tiscione, Nicholas B; Yeatman, Dustin Tate; Shan, Xiaoqin; Kahl, Joseph H

    2013-10-01

    Volatiles are frequently abused as inhalants. The methods used for identification are generally nonspecific if analyzed concurrently with ethanol or require an additional analytical procedure that employs mass spectrometry. A previously published technique utilizing a capillary flow technology splitter to simultaneously quantitate and confirm ethyl alcohol by flame ionization and mass spectrometric detection after headspace sampling and gas chromatographic separation was evaluated for the detection of inhalants. Methanol, isopropanol, acetone, acetaldehyde, toluene, methyl ethyl ketone, isoamyl alcohol, isobutyl alcohol, n-butyl alcohol, 1,1-difluoroethane, 1,1,1-trifluoroethane, 1,1,1,2-tetrafluoroethane (Norflurane, HFC-134a), chloroethane, trichlorofluoromethane (Freon®-11), dichlorodifluoromethane (Freon®-12), dichlorofluoromethane (Freon®-21), chlorodifluoromethane (Freon®-22) and 1,2-dichlorotetrafluoroethane (Freon®-114) were validated for qualitative identification by this method. The validation for qualitative identification included evaluation of matrix effects, sensitivity, carryover, specificity, repeatability and ruggedness/robustness.

  4. Mass spectrometric determination of acromelic acid A from a new poisonous mushroom: Clitocybe amoenolens.

    PubMed

    Bessard, J; Saviuc, P; Chane-Yene, Y; Monnet, S; Bessard, G

    2004-11-05

    As Clitocybe acromelalga, the mushroom Clitocybe amoenolens is responsible for erythermalgia. Acromelic acids isolated from C. acromelalga have been suspected to be to some extend the active principles. The objective was to develop a specific and sensitive liquid chromatographic-mass spectrometric method that would allow acromelic acid A identification and quantification in mushrooms. The method involved a single-step methanol-water extraction followed by a selective cleanup of the extract with solid-phase extraction cartridges (strong-anion exchange). The chromatographic separation was achieved on a porous graphitic carbon column with acetonitrile-water-formic acid as mobile phase. Detection was done with a mass analyzer equipped with a TurboIonSpray source, operated in the negative ionization mode. Acromelic acid A concentration was determined in dried mushroom at around 325 ng/mg in C. amoenolens and 283 ng/mg in C. acromelalga.

  5. Mass-spectrometric online monitoring of metabolism for estimation of adequacy of anesthesia

    NASA Astrophysics Data System (ADS)

    Elizarov, A. Yu.; Levshankov, A. I.; Faizov, I. I.; Shchegolev, A. V.

    2012-08-01

    The possibility of using a mass-spectrometric method for estimation of the adequacy of anesthesia has been demonstrated. The method is based on online monitoring of metabolism by determining the CO2/O2 concentration ratio during expiration in each breathing cycle, which allows the patient's response to surgical injury in the course of total anesthesia to be evaluated. The proposed method has been clinically tested using an electron-impact ionization mass spectrometer connected to the breathing circuit of an inhalation anesthesia machine. It is shown that, using this technique, the time of the patient's organism response to drug correction of the adequacy of lung ventilation during anesthesia can be monitored online.

  6. Gas chromatographic-mass spectrometric analysis of volatile amines produced by several strains of Clostridium.

    PubMed

    Pons, J L; Rimbault, A; Darbord, J C; Leluan, G

    1985-02-08

    A gas chromatographic--mass spectrometric technique is proposed for the analysis of volatile amines which were isolated from Clostridium cultures by vacuum distillation and concentrated as hydrochloride salts. Headspace sampling after alkalinization of the salts under vacuum was the most suitable for subsequent gas chromatographic analysis. With ammonia-loaded helium as carrier gas, methylamines were separated on 4.8% PEG 2OM + 0.3% potassium hydroxide on Carbopack B, and other volatile amines on 28% Pennwalt 223 + 4% potassium hydroxide on Gas-Chrom R. Bacterial volatile amines (dimethylamine, trimethylamine, isobutylamine, 3-methylbutylamine, etc.) were detected with a flame-ionization detector and identified by gas chromatography--mass spectrometry in electron-impact and chemical ionization modes.

  7. On-line mass spectrometric monitoring of the polymerization of a phenolic-resin-based material

    NASA Technical Reports Server (NTRS)

    Aikens, D. A.; Wood, G. M.; Upchurch, B. T.

    1975-01-01

    Polymerization of phenolic-resin-based materials requires elevated temperatures. The low thermal conductivity of these materials has led to the use of dielectric heating techniques in lieu of standard convection oven heating to obtain a satisfactory cure. The curing rate and therefore the quality of the cured material depends on the heating rate and maximum temperature attained, parameters which are extremely difficult to measure in dielectric heating units. The dielectric curing of these materials was monitored by using a mass spectrometer to measure the partial pressure of phenol in the gas evolved during polymerization. The resulting plots of phenol partial pressure as a function of time have a characteristic shape, and these may be used to indicate the attainment of complete curing. The validity of the mass spectrometric technique was confirmed by chemical analysis of the polymerized samples.

  8. Absorption spectrum, mass spectrometric properties, and electronic structure of 1,2-benzoquinone.

    PubMed

    Albarran, Guadalupe; Boggess, William; Rassolov, Vitaly; Schuler, Robert H

    2010-07-22

    Absorption spectrophotometric and mass spectrometric properties of 1,2-benzoquinone, prepared in aqueous solution by the hexachloroiridate(IV) oxidation of catechol and isolated by HPLC, are reported. Its absorption spectrum has a broad moderately intense band in the near UV with an extinction coefficient of 1370 M(-1)cm(-1) at its 389 nm maximum. The oscillator strength of this band contrasts with those of the order-of-magnitude stronger approximately 250 nm bands of most 1,4-benzoquinones. Gaussian analysis of its absorption spectrum indicates that it also has modestly intense higher energy bands in the 250-320 nm region. In atmospheric pressure mass spectrometric studies 1,2-benzoquinone exhibits very strong positive and negative mass 109 signals that result from the addition of protons and hydride ions in APCI and ESI ion sources. It is suggested that the hydride adduct is formed as the result of the highly polar character of ortho-quinone. On energetic collision the hydride adduct loses an H atom to produce the 1,2-benzosemiquinone radical anion. The present studies also show that atmospheric pressure mass spectral patterns observed for catechol are dominated by signals of 1,2-benzoquinone resulting from oxidation of catechol in the ion sources. Computational studies of the electronic structures of 1,2-benzoquinone, its proton and hydride ion adducts, and 1,2-benzosemiquinone radical anion are reported. These computational studies show that the structures of the proton and hydride adducts are similar and indicate that the hydride adduct is the proton adduct of a doubly negatively charged 1,2-benzoquinone. The contrast between the properties of 1,2- and 1,4-benzoquinone provides the basis for considerations on the effects of conjugation in aromatic systems.

  9. Mass spectrometric behaviour of carboxylated polyethylene glycols and carboxylated octylphenol ethoxylates.

    PubMed

    Frańska, Magdalena; Zgoła, Agnieszka; Rychłowska, Joanna; Szymański, Andrzej; Łukaszewski, Zenon; Frański, Rafał

    2003-01-01

    Mass spectrometric behaviour of mono- and di-carboxylated polyethylene glycols (PEGCs and CPEGCs) and carboxylated octylphenol ethoxylates (OPECs) are discussed. The tendency for ionisation (deprotonation, protonation and cationisation by alkali metal cations) of carboxylated PEGs was compared with that of non-carboxylated correspondents by using both secondary ion mass spectrometry (SIMS) and electrospray ionisation (ESI). The fragmentation of the PEGCs and CPEGCs is discussed and also compared with their neutral correspondents, PEGs. The B/E mass spectra were recorded, using secondary ion mass spectrometry as a method for generation, for deprotonated and protonated molecules and molecules cationised by alkali metal cations. The fragmentation behaviour of PEGs is found to be different from that of CPEGCs, The presence of carboxylic groups may be confirmed not only by the determination of molecular weights of the ethoxylates studied, but also on the basis of the fragment ions formed. The metastable decomposition of the [OPEC-H](-) ions proceed through the cleavage of the bond between the octylphenol moiety and the ethoxylene chain leading to the octylphenoxy anions. It permits determination of the mass of the hydrophobic moiety of the studied carboxylated alkylphenol ethoxylate. ESI mass spectra recorded in the negative ion mode were found to be more suitable for the determination of the average molecular weight of carboxylated ethoxylates than SI mass spectra.

  10. Cu2+-assisted two dimensional charge-mass double focusing gel electrophoresis and mass spectrometric analysis of histone variants.

    PubMed

    Zhang, Wenyang; Tang, Xuemei; Ding, Mengjie; Zhong, Hongying

    2014-12-10

    Abundant isoforms and dynamic posttranslational modifications cause the separation and identification of histone variants to be experimentally challenging. To meet this need, we employ two-dimensional electrophoretic gel separation followed by mass spectrometric detection which takes advantage of the chelation of Cu(2+) with amino acid residues exposed on the surfaces of the histone proteins. Acid-extracted rat liver histones were first mixed with CuSO4 solution and then separated in one dimension with triton-acid-urea (TAU) gel electrophoresis and in a second dimension using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The separations result from both the changes in charge and mass upon Cu(2+) chelation. Identities of each separated gel bands were obtained by using matrix-assisted laser desorption-ionization mass spectrometry (MALDI-MS). It was found that the migration of H3 histone isoforms of rat liver is markedly affected by the use of Cu(2+) ions.

  11. Increased Protein Structural Resolution from Diethylpyrocarbonate-based Covalent Labeling and Mass Spectrometric Detection

    PubMed Central

    Zhou, Yuping; Vachet, Richard W.

    2012-01-01

    Covalent labeling and mass spectrometry are seeing increased used together as a way to obtain insight into the 3-dimensional structure of proteins and protein complexes. Several amino acid specific (e.g. diethylpyrocarbonate) and non-specific (e.g. hydroxyl radicals) labeling reagents are available for this purpose. Diethylpyrocarbonate (DEPC) is a promising labeling reagent because it can potentially probe up to 30% of the residues in the average protein and gives only one reaction product, thereby facilitating mass spectrometric analysis. It was recently reported, though, that DEPC modifications are labile for some amino acids. Here, we show that label loss is more significant and widespread than previously thought, especially for Ser, Thr, Tyr, and His residues, when relatively long protein digestion times are used. Such label loss ultimately decreases the amount of protein structural information that is obtainable with this reagent. We find, however, that the number of DEPC modified residues, and thus protein structural information, can be significantly increased by decreasing the time between the covalent labeling reaction and the mass spectrometric analysis. This is most effectively accomplished using short (e.g. 2 h) proteolytic digestions with enzymes such as immobilized chymotrypsin or Glu-C rather than using methods (e.g. microwave or ultrasonic irradiation) that accelerate proteolysis in other ways. Using short digestion times, we show that the percentage of solvent accessible residues that can be modified by DEPC increases from 44% to 67% for cytochrome c, 35% to 81% for myoglobin, and 76% to 95% for β-2-microglobulin. In effect, these increased numbers of modified residues improve the protein structural resolution available from this covalent labeling method. As compared to typical overnight digestion conditions, the short digestion times decrease the average distance between modified residues from 11 Å to 7 Å for myoglobin, 13 Å to 10 Å for

  12. Liquid chromatography-mass spectrometric determination of rufinamide in low volume plasma samples.

    PubMed

    Gáll, Zsolt; Vancea, Szende; Dogaru, Maria T; Szilágyi, Tibor

    2013-12-01

    Quantification of rufinamide in plasma was achieved using a selective and sensitive liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method. The chromatographic separation was achieved on a reversed phase column (Zorbax SB-C18 100mm×3mm, 3.5μm) under isocratic conditions. The mobile phase consisted of a mixture of water containing 0.1% formic acid and methanol (50:50, v/v). The mass spectrometric detection of the analyte was in multiple reaction monitoring mode (MRM) using an electrospray positive ionization (ESI positive). The monitored ions were 127m/z derived from 239m/z rufinamide and 108m/z derived from 251m/z the internal standard (lacosamide). Protein precipitation with methanol was applied for sample preparation using only 50μl aliquots. The concentration range was 40-2000ng/ml for rufinamide in plasma. The limit of detection was 1.25ng/ml and the lower limit of quantification was established at 5ng/ml rufinamide concentration. Selectivity and matrix effect was verified using individual human, rat and rabbit plasma samples. Short-term, post-preparative and freeze-thaw stability was also investigated. The proposed method provides accuracy, precision and high-throughput (short runtime 4.5min) for quantitative determination of rufinamide in plasma. This is the first reported liquid chromatography-tandem mass spectrometric (LC-MS/MS) method for analysis of rufinamide from low volume plasma samples. The LC-MS/MS method was validated according to the current official guidelines and can be applied to accurately measure rufinamide level of large number of plasma samples from clinical studies or therapeutic drug monitoring. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Increased Protein Structural Resolution from Diethylpyrocarbonate-based Covalent Labeling and Mass Spectrometric Detection

    NASA Astrophysics Data System (ADS)

    Zhou, Yuping; Vachet, Richard W.

    2012-04-01

    Covalent labeling and mass spectrometry are seeing increased use together as a way to obtain insight into the 3-dimensional structure of proteins and protein complexes. Several amino acid specific (e.g., diethylpyrocarbonate) and non-specific (e.g., hydroxyl radicals) labeling reagents are available for this purpose. Diethylpyrocarbonate (DEPC) is a promising labeling reagent because it can potentially probe up to 30% of the residues in the average protein and gives only one reaction product, thereby facilitating mass spectrometric analysis. It was recently reported, though, that DEPC modifications are labile for some amino acids. Here, we show that label loss is more significant and widespread than previously thought, especially for Ser, Thr, Tyr, and His residues, when relatively long protein digestion times are used. Such label loss ultimately decreases the amount of protein structural information that is obtainable with this reagent. We find, however, that the number of DEPC modified residues and, thus, protein structural information, can be significantly increased by decreasing the time between the covalent labeling reaction and the mass spectrometric analysis. This is most effectively accomplished using short (e.g., 2 h) proteolytic digestions with enzymes such as immobilized chymotrypsin or Glu-C rather than using methods (e.g., microwave or ultrasonic irradiation) that accelerate proteolysis in other ways. Using short digestion times, we show that the percentage of solvent accessible residues that can be modified by DEPC increases from 44% to 67% for cytochrome c, 35% to 81% for myoglobin, and 76% to 95% for β-2-microglobulin. In effect, these increased numbers of modified residues improve the protein structural resolution available from this covalent labeling method. Compared with typical overnight digestion conditions, the short digestion times decrease the average distance between modified residues from 11 to 7 Å for myoglobin, 13 to 10 Å for

  14. Spark-source mass spectrometric assessment of silicon concentrations in silicon-doped gallium arsenide single crystals.

    PubMed

    Wiedemann, B; Meyer, J D; Jockel, D; Freyhardt, H C; Birkmann, B; Müller, G

    2001-07-01

    The spark-source mass spectrometric assessment of silicon concentrations in silicon-doped vertical-gradient-freeze gallium arsenide is presented. The silicon concentrations determined are compared with the charge-carrier densities measured by means of the Hall effect with van der Pauw symmetry along the axis of a single crystal.

  15. Differentiation of whole grain and refined wheat (T. aestivum) flour using a fuzzy mass spectrometric fingerprinting and chemometric approaches

    USDA-ARS?s Scientific Manuscript database

    A fuzzy mass spectrometric (MS) fingerprinting method combined with chemometric analysis was established to provide rapid discrimination between whole grain and refined wheat flour. Twenty one samples, including thirteen samples from three cultivars and eight from local grocery store, were studied....

  16. Method and apparatus for enhanced sequencing of complex molecules using surface-induced dissociation in conjunction with mass spectrometric analysis

    DOEpatents

    Laskin, Julia [Richland, WA; Futrell, Jean H [Richland, WA

    2008-04-29

    The invention relates to a method and apparatus for enhanced sequencing of complex molecules using surface-induced dissociation (SID) in conjunction with mass spectrometric analysis. Results demonstrate formation of a wide distribution of structure-specific fragments having wide sequence coverage useful for sequencing and identifying the complex molecules.

  17. Gas chromatographic-mass spectrometric analysis of plasma oxybutynin using a deuterated internal standard.

    PubMed

    Patrick, K S; Markowitz, J S; Jarvi, E J; Straughn, A B; Meyer, M C

    1989-01-27

    A gas chromatographic-mass spectrometric method is described for the quantitative analysis of plasma oxybutynin. Deuterated oxybutynin served as the internal standard and its synthesis is described. Chromatographic separation on a methylsilicone capillary column avoided the thermal decomposition observed using a packed column. Electron-impact ionization and selected-ion monitoring of the alpha-cleavage fragments of drug and internal standard permitted quantitation of oxybutynin down to 0.25 ng/ml of plasma. At the 2 ng/ml level the accuracy and precision are 4 and 10%, respectively, and improved at higher drug concentrations. Application of the method to the pharmacokinetics of oral oxybutynin in man demonstrated rapid absorption and elimination of the drug.

  18. Direct Electrospray Ionization Mass Spectrometric Profiling of Real-World Samples via a Solid Sampling Probe

    NASA Astrophysics Data System (ADS)

    Yu, Zhan; Chen, Lee Chuin; Mandal, Mridul Kanti; Yoshimura, Kentaro; Takeda, Sen; Hiraoka, Kenzo

    2013-10-01

    This study presents a novel direct analysis strategy for rapid mass spectrometric profiling of biochemicals in real-world samples via a direct sampling probe (DSP) without sample pretreatments. Chemical modification is applied to a disposable stainless steel acupuncture needle to enhance its surface area and hydrophilicity. After insertion into real-world samples, biofluid can be attached on the DSP surface. With the presence of a high DC voltage and solvent vapor condensing on the tip of the DSP, analyte can be dissolved and electrosprayed. The simplicity in design, versatility in application aspects, and other advantages such as low cost and disposability make this new method a competitive tool for direct analysis of real-world samples.

  19. N-dephenylation of CERM 3517 (mociprazine) in beagle dogs. A mass spectrometric determination.

    PubMed

    Pognat, J F; Enreille, A; Chabard, J L; Busch, N; Berger, J A

    1986-01-01

    CERM 3517 (mociprazine), a new antiemetic compound, was administered orally at 10 mg/kg twice a day for 4 days to six Beagle dogs in order to identify the major metabolite. Mass spectrometric comparison of this metabolite and a synthesized reference compound (CERM 4082) showed that both had identical structures. The metabolite originated from cleavage of the aromatic moiety. After iv administration of CERM 3517 (0.9 mg/kg) and CERM 4082 (0.6 mg/kg) to five beagle dogs, 13% and 56% of the dose, respectively, were eliminated in the urine as CERM 4082 compound. It can be calculated that at least 25% of CERM 3517 was biotransformed by N-dephenylation.

  20. Mass spectrometric analysis of EPO IEF-PAGE interfering substances in nitrile examination gloves.

    PubMed

    Reichel, Christian

    2012-10-01

    Direct detection of doping with recombinant erythropoietins (rhEPO) is accomplished by isoelectric focusing (IEF) or sodium dodecylsulfate (SDS) polyacrylamide gel electrophoresis (PAGE). In a recent publication, Lasne et al. (Electrophoresis 2011, 32, 1444) showed that improper use of nitrile examination gloves during sample collection, sample preparation, and IEF-PAGE may lead to distorted or absent EPO IEF-profiles. In order to clarify which substances are responsible for this observation, a mass spectrometric study on water extractable compounds found in nitrile gloves was performed. Several substance classes were shown to be present, among them polyethylene glycols (PEG), anionic and nonionic surfactants, as well as alcohol ethoxylates and plasticizers. It could be demonstrated that alkylbenzenesulfonates, the main category of detectable anionic detergents, and among them sodium dodecylbenzenesulfonate (SDBS) and its homologs, are the prime reason for the interference of nitrile gloves with EPO IEF-PAGE. Copyright © 2012 John Wiley & Sons, Ltd.

  1. Use of Composite Protein Database including Search Result Sequences for Mass Spectrometric Analysis of Cell Secretome

    PubMed Central

    Shin, Jihye; Kim, Gamin; Kabir, Mohammad Humayun; Park, Seong Jun; Lee, Seoung Taek; Lee, Cheolju

    2015-01-01

    Mass spectrometric (MS) data of human cell secretomes are usually run through the conventional human database for identification. However, the search may result in false identifications due to contamination of the secretome with fetal bovine serum (FBS) proteins. To overcome this challenge, here we provide a composite protein database including human as well as 199 FBS protein sequences for MS data search of human cell secretomes. Searching against the human-FBS database returned more reliable results with fewer false-positive and false-negative identifications compared to using either a human only database or a human-bovine database. Furthermore, the improved results validated our strategy without complex experiments like SILAC. We expect our strategy to improve the accuracy of human secreted protein identification and to also add value for general use. PMID:25822838

  2. Mass spectrometric imaging of flavonoid glycosides and biflavonoids in Ginkgo biloba L.

    PubMed

    Beck, Sebastian; Stengel, Julia

    2016-10-01

    Ginkgo biloba L. is known to be rich in flavonoids and flavonoid glycosides. However, the distribution within specific plant organs (e.g. within leaves) is not known. By using HPLC-MS and MS/MS we have identified a number of previously known G. biloba flavonoid glycosides and biflavonoids from leaves. Namely, kaempferol, quercetin, isorhamnetin, myricetin, laricitrin/mearnsetin and apigenin glycosides were identified. Furthermore, biflavonoids like ginkgetin/isoginkgetin were also detected. The application of MALDI mass spectrometric imaging, enabled the compilation of concentration profiles of flavonoid glycosides and biflavonoids in G. biloba L. leaves. Both, flavonoid glycosides and biflavonoids show a distinct distribution in leaf thin sections of G. biloba L.

  3. An accelerated mass spectrometric method for measuring myo-inositol in phosphatidylinositol in rat brain

    NASA Astrophysics Data System (ADS)

    Deutsch, Joseph; Ma, Kaizung; Rapoport, Stanley I.

    2006-03-01

    A fast and efficient chemical ionization mass spectrometric (CI-GC-MS) method for measuring myo-inositol in phosphatidylinositol (PtdIns) in rat brain has been developed. Previously, quantitation of PtdIns involved the release of the myo-inositol by two enzymatic reactions using phospholipase C and alkaline phosphatase. The hydrolytic action of these enzymes was replaced by using commercially available 48% hydrofluoric acid (HF) at 80 °C for 30 min. The process can be carried out on the crude Folch extract of brain phospholipids without prior thin layer chromatography (TLC) purification, thereby significantly increasing the speed of analysis. For quantification, unlabeled myo-inositol, labeled myo- and neo-inositol (internal standard) were converted to acetate derivatives and analyzed by CI-GC-MS.

  4. Regime Transition in Electromechanical Fluid Atomization and Implications to Analyte Ionization for Mass Spectrometric Analysis

    PubMed Central

    Forbes, Thomas P.; Degertekin, F. Levent; Fedorov, Andrei G.

    2015-01-01

    The physical processes governing the transition from purely mechanical ejection to electromechanical ejection to electrospraying are investigated through complementary scaling analysis and optical visualization. Experimental characterization and visualization are performed with the ultrasonically-driven array of micromachined ultrasonic electrospray (AMUSE) ion source to decouple the electrical and mechanical fields. A new dimensionless parameter, the Fenn number, is introduced to define a transition between the spray regimes, in terms of its dependence on the characteristic Strouhal number for the ejection process. A fundamental relationship between the Fenn and Strouhal numbers is theoretically derived and confirmed experimentally in spraying liquid electrolytes of different ionic strength subjected to a varying magnitude electric field. This relationship and the basic understanding of the charged droplet generation physics have direct implications on the optimal ionization efficiency and mass spectrometric response for different types of analytes. PMID:20729096

  5. Mass-spectrometric 230Th-234U-238U dating of the Devils Hole calcite vein

    USGS Publications Warehouse

    Ludwig, K. R.; Simmons, K.R.; Szabo, B. J.; Winograd, I.J.; Landwehr, J.M.; Riggs, A.C.; Hoffman, R.J.

    1992-01-01

    The Devils Hole calcite vein contains a long-term climatic record, but requires accurate chronologic control for its interpretation. Mass-spectrometric U-series ages for samples from core DH-11 yielded 230Th ages with precisions ranging from less than 1,000 years (2??) for samples younger than ???140 ka (thousands of years ago) to less than 50,000 years for the oldest samples (???566 ka). The 2348U/238U ages could be determined to a precision of ???20,000 years for all ages. Calcite accumulated continuously from 566 ka until ???60 ka at an average rate of 0.7 millimeter per 103 years. The precise agreement between replicate analyses and the concordance of the 230Th/238U and 234U/238U ages for the oldest samples indicate that the DH-11 samples were closed systems and validate the dating technique in general.

  6. Regime transition in electromechanical fluid atomization and implications to analyte ionization for mass spectrometric analysis.

    PubMed

    Forbes, Thomas P; Degertekin, F Levent; Fedorov, Andrei G

    2010-11-01

    The physical processes governing the transition from purely mechanical ejection to electromechanical ejection to electrospraying are investigated through complementary scaling analysis and optical visualization. Experimental characterization and visualization are performed with the ultrasonically-driven array of micromachined ultrasonic electrospray (AMUSE) ion source to decouple the electrical and mechanical fields. A new dimensionless parameter, the Fenn number, is introduced to define a transition between the spray regimes, in terms of its dependence on the characteristic Strouhal number for the ejection process. A fundamental relationship between the Fenn and Strouhal numbers is theoretically derived and confirmed experimentally in spraying liquid electrolytes of different ionic strength subjected to a varying magnitude electric field. This relationship and the basic understanding of the charged droplet generation physics have direct implications on the optimal ionization efficiency and mass spectrometric response for different types of analytes. Copyright © 2010. Published by Elsevier Inc.

  7. XMS: Cross-Platform Normalization Method for Multimodal Mass Spectrometric Tissue Profiling

    NASA Astrophysics Data System (ADS)

    Golf, Ottmar; Muirhead, Laura J.; Speller, Abigail; Balog, Júlia; Abbassi-Ghadi, Nima; Kumar, Sacheen; Mróz, Anna; Veselkov, Kirill; Takáts, Zoltán

    2015-01-01

    Here we present a proof of concept cross-platform normalization approach to convert raw mass spectra acquired by distinct desorption ionization methods and/or instrumental setups to cross-platform normalized analyte profiles. The initial step of the workflow is database driven peak annotation followed by summarization of peak intensities of different ions from the same molecule. The resulting compound-intensity spectra are adjusted to a method-independent intensity scale by using predetermined, compound-specific normalization factors. The method is based on the assumption that distinct MS-based platforms capture a similar set of chemical species in a biological sample, though these species may exhibit platform-specific molecular ion intensity distribution patterns. The method was validated on two sample sets of (1) porcine tissue analyzed by laser desorption ionization (LDI), desorption electrospray ionization (DESI), and rapid evaporative ionization mass spectrometric (REIMS) in combination with Fourier transformation-based mass spectrometry; and (2) healthy/cancerous colorectal tissue analyzed by DESI and REIMS with the latter being combined with time-of-flight mass spectrometry. We demonstrate the capacity of our method to reduce MS-platform specific variation resulting in (1) high inter-platform concordance coefficients of analyte intensities; (2) clear principal component based clustering of analyte profiles according to histological tissue types, irrespective of the used desorption ionization technique or mass spectrometer; and (3) accurate "blind" classification of histologic tissue types using cross-platform normalized analyte profiles.

  8. Mass Spectrometric Imaging Using Laser Ablation and Solvent Capture by Aspiration (LASCA)

    NASA Astrophysics Data System (ADS)

    Brauer, Jonathan I.; Beech, Iwona B.; Sunner, Jan

    2015-09-01

    A novel interface for ambient, laser ablation-based mass spectrometric imaging (MSI) referred to as laser ablation and solvent capture by aspiration (LASCA) is presented and its performance demonstrated using selected, unaltered biological materials. LASCA employs a pulsed 2.94 μm laser beam for specimen ablation. Ablated materials in the laser plumes are collected on a hanging solvent droplet with electric field-enhanced trapping, followed by aspiration of droplets and remaining plume material in the form of a coarse aerosol into a collection capillary. The gas and liquid phases are subsequently separated in a 10 μL-volume separatory funnel, and the solution is analyzed with electrospray ionization in a high mass resolution Q-ToF mass spectrometer. The LASCA system separates the sampling and ionization steps in MSI and combines high efficiencies of laser plume sampling and of electrospray ionization (ESI) with high mass resolution MS. Up to 2000 different compounds are detected from a single ablation spot (pixel). Using the LASCA platform, rapid (6 s per pixel), high sensitivity, high mass-resolution ambient imaging of "as-received" biological material is achieved routinely and reproducibly.

  9. Mass spectrometric detection of peginesatide in human urine in doping control analysis.

    PubMed

    Möller, Ines; Thomas, Andreas; Delahaut, Philippe; Geyer, Hans; Schänzer, Wilhelm; Thevis, Mario

    2012-11-01

    Erythropoiesis-stimulating agents (ESAs) have frequently been confessed to be illicitly used in elite sports due to their endurance enhancing effects. Recently, peginesatide, the first representative of a new generation of ESAs, referred to as Erythropoietin (EPO)-mimetic peptides, obtained approval in the USA under the trade name Omontys(®) for the treatment of anaemic patients. Lacking sequence homology with EPO, it consists of a pegylated homodimeric peptide of approximately 45 kDa, and thus, specific approaches for the determination of peginesatide in blood were developed as conventional detection assays for EPO do not allow for the analysis of the EPO-mimetic peptides. However, as urine specimens are the most frequently provided doping control samples and pharmacokinetic studies conducted in rats and monkeys revealed the excretion of the pegylated peptide into urine, a detection method for peginesatide in urine would be desirable. A mass spectrometric assay in human urine was developed consisting of protein precipitation with acetonitrile followed by proteolytic digestion after the removal of the acetonitrile fraction under reduced pressure. Purification and concentration of the resulting proteotypic target peptide was accomplished by means of solid-phase extraction on strong cation-exchange resin prior to liquid chromatographic-tandem mass spectrometric analysis. Method validation was performed for qualitative purposes and demonstrated specificity, precision, linearity as well as sufficient sensitivity (limit of detection: 0.5 ng/ml) while proof-of-concept for the applicability of the assay for the determination of peginesatide in authentic urine samples was obtained by analyzing animal in vivo specimens collected after a single i.v. administration of peginesatide over a period of 4 days. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Liquid chromatography-mass spectrometric determination of losartan and its active metabolite on dried blood spots.

    PubMed

    Rao, R Nageswara; Raju, S Satyanarayana; Vali, R Mastan; Sankar, G Girija

    2012-08-01

    A simple and rapid quantitative bioanalytical liquid chromatography-tandem mass spectrometric (LC-MS/MS) method for simultaneous determination of losartan and its active metabolite, losartan carboxylic acid on rat dried blood spots was developed and validated as per regulatory guidelines. Losartan and its metabolite were extracted from dried blood spots using 50% aqueous methanol and separated on Waters XTerra(®) RP18 (250 mm × 4.6 mm, 5 μm) column using mobile phase composed of 40% acetonitrile and 60% aqueous ammonium acetate (10mM). The eluents were monitored using ESI tandem mass spectrometric detection with negative polarity in MRM mode using ion transitions m/z 421.2→179.0, m/z 435.3→157.0 and m/z 427.3→193.0 for losartan, losartan carboxylic acid and Irbesartan (internal standard), respectively. The method was validated over the linear range of 1-200 ng/mL and 5-1000 ng/mL with lower limits of quantification of 1.0 ng/mL and 5.0 ng/mL for losartan and losartan carboxylic acid, respectively. Inter and intra-day precision and accuracy (Bias) were below 5.96% and between -2.8 and 1.5%, respectively. The mean recoveries of the analytes from dried blood spots were between 89% and 97%. No significant carry over and matrix effects were observed. The stability of stock solution, whole blood, dried blood spot and processed samples were tested under different conditions and the results were found to be well within the acceptable limits. Additional validation parameters such as influence of hematocrit and spot volume were also evaluated and found to be well within the acceptable limits.

  11. iPE-MMR: An integrated approach to accurately assign monoisotopic precursor masses to tandem mass spectrometric data

    PubMed Central

    Jung, Hee-Jung; Purvine, Samuel O.; Kim, Hokeun; Petyuk, Vladislav A.; Hyung, Seok-Won; Monroe, Matthew E.; Mun, Dong-Gi; Kim, Kyong-Chul; Park, Jong-Moon; Kim, Su-Jin; Tolic, Nikola; Slysz, Gordon W.; Moore, Ronald J.; Zhao, Rui; Adkins, Joshua N.; Anderson, Gordon A.; Lee, Hookeun; Camp, David G.; Yu, Myeong-Hee; Smith, Richard D.; Lee, Sang-Won

    2010-01-01

    Accurate assignment of monoisotopic precursor masses to tandem mass spectrometric (MS/MS) data is a fundamental and critically important step for successful peptide identifications in mass spectrometry based proteomics. Here we describe an integrated approach that combines three previously reported methods of treating MS/MS data for precursor mass refinement. This combined method, “integrated Post-Experiment Monoisotopic Mass Refinement” (iPE-MMR), integrates steps: 1) generation of refined MS/MS data by DeconMSn; 2) additional refinement of the resultant MS/MS data by a modified version of PE-MMR; 3) elimination of systematic errors of precursor masses using DtaRefinery. iPE-MMR is the first method that utilizes all MS information from multiple MS scans of a precursor ion including multiple charge states, in an MS scan, to determine precursor mass. By combining these methods, iPE-MMR increases sensitivity in peptide identification and provides increased accuracy when applied to complex high-throughput proteomics data. PMID:20863060

  12. A Portable and Autonomous Mass Spectrometric System for On-Site Environmental Gas Analysis.

    PubMed

    Brennwald, Matthias S; Schmidt, Mark; Oser, Julian; Kipfer, Rolf

    2016-12-20

    We developed a portable mass spectrometric system ("miniRuedi") for quantificaton of the partial pressures of He, Ne (in dry gas), Ar, Kr, N2, O2, CO2, and CH4 in gaseous and aqueous matrices in environmental systems with an analytical uncertainty of 1-3%. The miniRuedi does not require any purification or other preparation of the sampled gases and therefore allows maintenance-free and autonomous operation. The apparatus is most suitable for on-site gas analysis during field work and at remote locations due to its small size (60 cm × 40 cm × 14 cm), low weight (13 kg), and low power consumption (50 W). The gases are continuously sampled and transferred through a capillary pressure reduction system into a vacuum chamber, where they are analyzed using a quadrupole mass spectrometer with a time resolution of ≲1 min. The low gas consumption rate (<0.1 mL/min) minimizes interference with the natural mass balance of gases in environmental systems, and allows the unbiased quantification of dissolved-gas concentrations in water by gas/water equilibration using membrane contractors (gas-equilibrium membrane-inlet mass spectrometry, GE-MIMS). The performance of the miniRuedi is demonstrated in laboratory and field tests, and its utility is illustrated in field applications related to soil-gas formation, lake/atmosphere gas exchange, and seafloor gas emanations.

  13. Mass spectrometric characterization of the neuropeptidome of the ghost crab Ocypode ceratophthalma (Brachyura, Ocypodidae).

    PubMed

    Hui, Limei; D'Andrea, Brandon T; Jia, Chenxi; Liang, Zhidan; Christie, Andrew E; Li, Lingjun

    2013-04-01

    The horn-eyed ghost crab Ocypode ceratophthalma is a terrestrial brachyuran native to the Indo-Pacific region, including the islands of Hawaii. Here, multiple mass spectrometric platforms, including matrix-assisted laser desorption/ionization time-of-flight/time-of-flight tandem mass spectrometry (MALDI-TOF/TOF MS) and nanoflow liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (nanoLC-ESI-Q-TOF MS/MS), were used to characterize the neuropeptidome of this species. In total, 156 peptide paracrines/hormones, representing 15 peptide families, were identified from the O. ceratophthalma supraesophageal ganglion (brain), eyestalk ganglia, pericardial organ and/or sinus gland, including 59 neuropeptides de novo sequenced here for the first time. Among the de novo sequenced peptides were isoforms of A-type allatostatin, B-type allatostatin, FMRFamide-like peptide (FLP), orcokinin, orcomyotropin and RYamide. Of particular note, were several novel FLPs including DVRAPALRLRFamide, an isoform of short neuropeptide F, and NRSNLRFamide, the orcokinins NFDEIDRSGYGFV and DFDEIDRSSFGFH, which exhibit novel Y for F and D for N substitutions at positions 10 and 1, respectively, and FDAYTTGFGHS, a member of the orcomyotropin family exhibiting a novel Y for F substitution at position 4. Taken collectively, the set of peptides described here represents the largest number of neuropeptides thus far characterized via mass spectrometry from any single crustacean, and provides a framework for future investigations of the physiological roles played by these molecules in this species.

  14. Top-down mass spectrometric approach for the full characterization of insulin-cisplatin adducts.

    PubMed

    Moreno-Gordaliza, Estefanía; Cañas, Benito; Palacios, María A; Gómez-Gómez, M Milagros

    2009-05-01

    The interaction of the antitumor drug cisplatin with insulin was studied using a top-down mass spectrometric approach. In vitro incubations were prepared under acidic and physiological conditions at different insulin/cisplatin molar ratios for different incubation times. Size exclusion chromatography-inductively coupled plasma mass spectrometry (SEC-ICPMS) analysis enabled the specific detection of platinum containing species attributed to the binding of the drug to the protein. Further analysis through matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) and nanoelectrospray ionization mass spectrometry using a linear ion trap (nESI-LIT-MS) allowed the identification of platinated mono-, di-, and even triadducts in the incubations. Platinum binding sites were identified by CID-MS(n) as B chain N-terminus, His5, and probably His10 residues, which turned out to be the same, regardless of the incubation conditions. Evidence on the binding of Pt to B chain Cys7 was also observed. Working with the LIT zoom scan mode provides enough resolution to discern the isotopic pattern for both precursor and fragment ions, allowing the differentiation of platinum-containing ions. The elucidation of platinum binding sites in a native protein through a top-down approach has been performed for the first time with this type of instrument.

  15. Mass spectrometric characterization of the neuropeptidome of the ghost crab Ocypode ceratophthalma (Brachyura, Ocypodidae)

    PubMed Central

    Hui, Limei; D’Andrea, Brandon T.; Jia, Chenxi; Liang, Zhidan; Christie, Andrew E.; Li, Lingun

    2013-01-01

    The horn-eyed ghost crab Ocypode ceratophthalma is a terrestrial brachyuran native to the Indo-Pacific region, including the islands of Hawaii. Here, multiple mass spectrometric platforms, including matrix-assisted laser desorption/ionization time-of-flight/time-of-flight tandem mass spectrometry (MALDI-TOF/TOF MS/MS) and nanoflow liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (nanoLC-ESI-Q-TOF MS/MS), were used to characterize the neuropeptidome of this species. In total, 156 peptide paracrines/hormones, representing 15 peptide families, were identified from the O. ceratophthalma supraesophageal ganglion (brain), eyestalk ganglia, pericardial organ and/or sinus gland, including 59 neuropeptides de novo sequenced here for the first time. Among the de novo sequenced peptides were isoforms of A-type allatostatin, B-type allatostatin, FMRFamide-like peptide (FLP), orcokinin, orcomyotropin and RYamide. Of particular note, were several novel FLPs including DVRAPALRLRFamide, an isoform of short neuropeptide F, and NRSNLRFamide, the orcokinins NFDEIDRSGYGFV and DFDEIDRSSFGFH, which exhibit novel Y for F and D for N substitutions at positions 10 and 1, respectively, and FDAYTTGFGHS, a member of the orcomyotropin family exhibiting a novel Y for F substitution at position 4. Taken collectively, the set of peptides described here represents the largest number of neuropeptides thus far characterized via mass spectrometry from any single crustacean, and provides a framework for future investigations of the physiological roles played by these molecules in this species. PMID:23298572

  16. Mass spectrometric techniques for characterizing low-molecular-weight resins used as paint varnishes.

    PubMed

    Bonaduce, I; Colombini, M P; Degano, I; Di Girolamo, F; La Nasa, J; Modugno, F; Orsini, S

    2013-01-01

    The molecular structure of three low-molecular-weight resins used as paint varnishes has been characterized by use of an approach based on three different mass spectrometric techniques. We investigated the ketone resin MS2A, the aldehyde resin Laropal A81, and the hydrocarbon resin Regalrez 1094, now commonly used in restoration. To date, the molecular structures of these resins have not been completely elucidated. To improve current knowledge of the chemical composition of these materials, information obtained by gas chromatography-mass spectrometry (GC/MS), pyrolysis-gas chromatography-mass spectrometry (Py/GC/MS), and electrospray ionization mass spectrometry (ESI-Q-ToF) was combined. Analysis, in solution, of the whole polymeric fraction of the resins by flow-injection ESI-Q-ToF, and of the non-polymeric fraction by GC-MS, enabled us to identify previously unreported features of the polymer structures. In addition, the Py-GC/MS profiles that we obtained will help to enhance the databases currently available in the literature. The proposed approach can be extended to other low-molecular-weight resins used as varnishes in conservation.

  17. Spatial correlation of confocal Raman scattering and secondary ion mass spectrometric molecular images of lignocellulosic materials.

    PubMed

    Li, Zhen; Chu, Li-Qiang; Sweedler, Jonathan V; Bohn, Paul W

    2010-04-01

    A detailed chemical and structural understanding of pre-enzymatic processing of lignocellulosic materials (LCMs) is a key objective in the development of renewable energy. Efficient rendering of biomass components into fermentable substrates for conversion into biofuel feedstocks would benefit greatly from the development of new technologies to provide high-quality, spatially resolved chemical information about LCMs during the various processing states. In an effort to realize this important goal, spatially correlated confocal Raman and mass spectrometric images allow the extraction of three-dimensional information from the perennial grass, Miscanthus x giganteus. An optical microscopy-based landmark registry scheme was developed that allows samples to be transferred between laboratories at different institutions, while retaining the capability to access the same physical regions of the samples. Subsequent to higher resolution imaging via confocal Raman microscopy and secondary ion mass spectrometry (SIMS), laser desorption-ionization mass spectrometry was used to place these regions within the overall sample architecture. Excellent sample registry was evident in the highly correlated Raman and SIMS images. In addition, the correlation of vibrational Raman scattering with mass spectra from specific spatial locations allowed confirmation of the assignment of intracellular globular structures to hemicellulose-rich lignin complexes, an assignment which could only be made tentatively from either image alone.

  18. Skeletal muscle fiber analysis by atmospheric pressure scanning microprobe matrix-assisted laser desorption/ionization mass spectrometric imaging at high mass and high spatial resolution.

    PubMed

    Tsai, Yu-Hsuan; Bhandari, Dhaka Ram; Garrett, Timothy J; Carter, Christy S; Spengler, Bernhard; Yost, Richard A

    2016-06-01

    Skeletal muscles are composed of heterogeneous muscle fibers with various fiber types. These fibers can be classified into different classes based on their different characteristics. MALDI mass spectrometric imaging (MSI) has been applied to study and visualize different metabolomics profiles of different fiber types. Here, skeletal muscles were analyzed by atmospheric pressure scanning microprobe MALDI-MSI at high spatial and high mass resolution.

  19. Gene analysis using mass spectrometric cleaved amplified polymorphic sequence (MS-CAPS) with matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF).

    PubMed

    Kajiwara, Hideyuki

    2015-01-01

    Mass spectrometric cleaved amplified polymorphic sequence (MS-CAPS) is a method for detecting genes using a combination of short PCR and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). MS-CAPS can identify a single nucleotide polymorphism (SNP) in less than one hour and is suitable for plants, animals, bacteria, and food.

  20. Mass spectrometric characterization of the selective androgen receptor modulator (SARM) YK-11 for doping control purposes.

    PubMed

    Thevis, Mario; Piper, Thomas; Dib, Josef; Lagojda, Andreas; Kühne, Dirk; Packschies, Lars; Geyer, Hans; Schänzer, Wilhelm

    2017-07-30

    Selective androgen receptor modulators (SARMs) represent an emerging class of therapeutics targeting inter alia conditions referred to as cachexia and sarcopenia. Due to their anabolic properties, the use of SARMs is prohibited in sports as regulated by the World Anti-Doping Agency (WADA), and doping control laboratories test for these anabolic agents in blood and urine. In order to accomplish and maintain comprehensive test methods, the characterization of new drug candidates is critical for efficient sports drug testing. Hence, in the present study the mass spectrometric properties of the SARM YK-11 were investigated. YK-11 was synthesized according to literature data and three different stable-isotope-labeled analogs were prepared to support the mass spectrometric studies. Using high-resolution/high-accuracy mass spectrometry following electrospray ionization as well as electron ionization, the dissociation pathways of YK-11 were investigated, and characteristic features of its (product ion) mass spectra were elucidated. These studies were flanked by density functional theory (DFT) computation providing information on proton affinities of selected functional groups of the analyte. The steroidal SARM YK-11 was found to readily protonate under ESI conditions followed by substantial in-source dissociation processes eliminating methanol, acetic acid methyl ester, and/or ketene. DFT computation yielded energetically favored structures of the protonated species resulting from the aforementioned elimination processes particularly following protonation of the steroidal D-ring substituent. Underlying dissociation pathways were suggested, supported by stable-isotope labeling of the analyte, and diagnostic product ions for the steroidal nucleus and the D-ring substituent were identified. Further, trimethylsilylated YK-11 and its deuterated analogs were subjected to electron ionization high-resolution/high-accuracy mass spectrometry, complementing the dataset characterizing

  1. Extraction and chromatography-mass spectrometric analysis of the active principles from selected Chinese herbs and other medicinal plants.

    PubMed

    Wang, Xiaosuo; Kapoor, Vimal; Smythe, George A

    2003-01-01

    Medicinal herbs have a long history of use in the practice of traditional Chinese medicine and a substantial body of evidence has, over recent decades, demonstrated a range of important pharmacological properties. Western biomedical researchers are examining not only the efficacy of the traditional herbal products but, through the use of a range of bioassays and analytical techniques, are developing improved methods to isolate and characterize active components. This review briefly describes the different extraction methodologies used in the preparation of herbal extracts and reviews the utility of chromatography-mass spectrometry for the analysis of their active components. In particular, applications of gas or liquid chromatography with mass spectrometry for the isolation and characterization of active components of ginseng are critically assessed. The analysis of toxic substances from herb extracts with mass spectrometric techniques is also discussed along with the potential for mass spectrometric methods to investigate the proteomics of herbal extracts.

  2. A novel mass spectrometric strategy “BEMAP” reveals Extensive O-linked protein glycosylation in Enterotoxigenic Escherichia coli

    PubMed Central

    Boysen, Anders; Palmisano, Giuseppe; Krogh, Thøger Jensen; Duggin, Iain G.; Larsen, Martin R.; Møller-Jensen, Jakob

    2016-01-01

    The attachment of sugars to proteins via side-chain oxygen atoms (O-linked glycosylation) is seen in all three domains of life. However, a lack of widely-applicable analytical tools has restricted the study of this process, particularly in bacteria. In E. coli, only four O-linked glycoproteins have previously been characterized. Here we present a glycoproteomics technique, termed BEMAP, which is based on the beta-elimination of O-linked glycans followed by Michael-addition of a phosphonic acid derivative, and subsequent titanium dioxide enrichment. This strategy allows site-specific mass-spectrometric identification of proteins with O-linked glycan modifications in a complex biological sample. Using BEMAP we identified cell surface-associated and membrane vesicle glycoproteins from Enterotoxigenic E. coli (ETEC) and non-pathogenic E. coli K-12. We identified 618 glycosylated Serine and Threonine residues mapping to 140 proteins in ETEC, including several known virulence factors, and 34 in E. coli K-12. The two strains had 32 glycoproteins in common. Remarkably, the majority of the ETEC glycoproteins were conserved in both strains but nevertheless were only glycosylated in the pathogen. Therefore, bacterial O-linked glycosylation is much more extensive than previously thought, and is especially important to the pathogen. PMID:27562176

  3. A novel mass spectrometric strategy "BEMAP" reveals Extensive O-linked protein glycosylation in Enterotoxigenic Escherichia coli.

    PubMed

    Boysen, Anders; Palmisano, Giuseppe; Krogh, Thøger Jensen; Duggin, Iain G; Larsen, Martin R; Møller-Jensen, Jakob

    2016-08-26

    The attachment of sugars to proteins via side-chain oxygen atoms (O-linked glycosylation) is seen in all three domains of life. However, a lack of widely-applicable analytical tools has restricted the study of this process, particularly in bacteria. In E. coli, only four O-linked glycoproteins have previously been characterized. Here we present a glycoproteomics technique, termed BEMAP, which is based on the beta-elimination of O-linked glycans followed by Michael-addition of a phosphonic acid derivative, and subsequent titanium dioxide enrichment. This strategy allows site-specific mass-spectrometric identification of proteins with O-linked glycan modifications in a complex biological sample. Using BEMAP we identified cell surface-associated and membrane vesicle glycoproteins from Enterotoxigenic E. coli (ETEC) and non-pathogenic E. coli K-12. We identified 618 glycosylated Serine and Threonine residues mapping to 140 proteins in ETEC, including several known virulence factors, and 34 in E. coli K-12. The two strains had 32 glycoproteins in common. Remarkably, the majority of the ETEC glycoproteins were conserved in both strains but nevertheless were only glycosylated in the pathogen. Therefore, bacterial O-linked glycosylation is much more extensive than previously thought, and is especially important to the pathogen.

  4. Measurement of oxidatively induced DNA damage and its repair, by mass spectrometric techniques.

    PubMed

    Dizdaroglu, M; Coskun, E; Jaruga, P

    2015-05-01

    Oxidatively induced damage caused by free radicals and other DNA-damaging agents generate a plethora of products in the DNA of living organisms. There is mounting evidence for the involvement of this type of damage in the etiology of numerous diseases including carcinogenesis. For a thorough understanding of the mechanisms, cellular repair, and biological consequences of DNA damage, accurate measurement of resulting products must be achieved. There are various analytical techniques, with their own advantages and drawbacks, which can be used for this purpose. Mass spectrometric techniques with isotope dilution, which include gas chromatography (GC) and liquid chromatography (LC), provide structural elucidation of products and ascertain accurate quantification, which are absolutely necessary for reliable measurement. Both gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-mass spectrometry (LC-MS), in single or tandem versions, have been used for the measurement of numerous DNA products such as sugar and base lesions, 8,5'-cyclopurine-2'-deoxynucleosides, base-base tandem lesions, and DNA-protein crosslinks, in vitro and in vivo. This article reviews these techniques and their applications in the measurement of oxidatively induced DNA damage and its repair.

  5. Gas chromatographic and mass spectrometric analysis of polychlorinated biphenyls in human placenta and cord blood

    SciTech Connect

    Ando, M.; Saito, H.; Wakisaka, I.

    1986-10-01

    Gas chromatographic and mass spectrometric analyses of polychlorinated biphenyls (PCBs) in placenta, maternal blood, cord blood, and milk were carried out. Trichlorobiphenyl, tetrachlorobiphenyl, pentachlorobiphenyls, and hexachlorobiphenyls were identified by the mass chromatogram and the mass spectra. Some minor peaks of PCBs were identified by gas chromatography. The relationship between the PCB concentration in placenta and that in milk is different in each PCB congener. The higher the chlorine content of the PCB congener, the more significant the correlation. No significant but a low negative correlation exists between the concentration of some PCB congeners in the placenta and that in cord blood. On the other hand, a significant linear correlation exists between the concentration of hexachlorobenzene in the placenta and that in cord blood. The transplacental transport of each PCB congener varied depending upon its chemical nature. Trichlorobiphenyl and tetrachlorobiphenyl were more transferable than hexachlorobiphenyls. The results show that the placenta and cord blood are useful human samples to analyze the body burden of environmental pollutants and to estimate their transfer from mother to fetus.

  6. Mass spectrometric survey of peptides in cephalopods with an emphasis on the FMRFamide-related peptides.

    PubMed

    Sweedler, J V; Li, L; Floyd, P; Gilly, W

    2000-12-01

    A matrix-assisted laser desorption/ionization (MALDI) mass spectrometric (MS) survey of the major peptides in the stellar, fin and pallial nerves and the posterior chromatophore lobe of the cephalopods Sepia officinalis, Loligo opalescens and Dosidicus gigas has been performed. Although a large number of putative peptides are distinct among the three species, several molecular masses are conserved. In addition to peptides, characterization of the lipid content of the nerves is reported, and these lipid peaks account for many of the lower molecular masses observed. One conserved set of peaks corresponds to the FMRFamide-related peptides (FRPs). The Loligo opalescens FMRFa gene has been sequenced. It encodes a 331 amino acid residue prohormone that is processed into 14 FRPs, which are both predicted by the nucleotide sequence and confirmed by MALDI MS. The FRPs predicted by this gene (FMRFa, FLRFa/FIRFa and ALSGDAFLRFa) are observed in all three species, indicating that members of this peptide family are highly conserved across cephalopods.

  7. Characterisation of natural indigo and shellfish purple by mass spectrometric techniques.

    PubMed

    Andreotti, Alessia; Bonaduce, Ilaria; Colombini, Maria Perla; Ribechini, Erika

    2004-01-01

    Two analytical methods based on mass spectrometry were used in the characterisation of constituents of natural indigo prepared from the leaves of Indigofera tinctoria, and of shellfish purple prepared from the hypobranchial glandular secretions of Murex trunculus, following old recipes. On-line pyrolysis gas chromatography in the presence of hexamethyldisilazane followed by mass spectrometric analysis (Py-silylation/GC/MS), and direct exposure mass spectrometry (DE-MS), were used. Extensive fragmentation of indigoid dyes was obtained by Py-silylation/GC/MS. The following molecular markers were highlighted, which are useful for identification purposes: 1,2-dihydro-3H-indol-3-one for indigoid dyes, 1,3-dihydro-2H-indol-2-one for indirubine, and 6-bromo-1,2-dihydro-3H-indol-3-one for shellfish purple. Using DE-MS, 6,6'dibromoindigotine, monobromoindigotine and indigotine were identified as the main components, and the presence of tyrindoxyl, one of the dye precursors, was also assessed.

  8. Optimization and Comparison of Multiple MALDI Matrix Application Methods for Small Molecule Mass Spectrometric Imaging

    PubMed Central

    2015-01-01

    The matrix application technique is critical to the success of a matrix-assisted laser desorption/ionization (MALDI) experiment. This work presents a systematic study aiming to evaluate three different matrix application techniques for MALDI mass spectrometric imaging (MSI) of endogenous metabolites from legume plant, Medicago truncatula, root nodules. Airbrush, automatic sprayer, and sublimation matrix application methods were optimized individually for detection of metabolites in the positive ionization mode exploiting the two most widely used MALDI matrices, 2,5-dihydroxybenzoic acid (DHB) and α-cyano-4-hydroxycinnamic acid (CHCA). Analytical reproducibility and analyte diffusion were examined and compared side-by-side for each method. When using DHB, the optimized method developed for the automatic matrix sprayer system resulted in approximately double the number of metabolites detected when compared to sublimation and airbrush. The automatic sprayer method also showed more reproducible results and less analyte diffusion than the airbrush method. Sublimation matrix deposition yielded high spatial resolution and reproducibility but fewer analytes in the higher m/z range (500–1000 m/z). When the samples were placed in a humidity chamber after sublimation, there was enhanced detection of higher mass metabolites but increased analyte diffusion in the lower mass range. When using CHCA, the optimized automatic sprayer method and humidified sublimation method resulted in double the number of metabolites detected compared to standard airbrush method. PMID:25331774

  9. Optimization and comparison of multiple MALDI matrix application methods for small molecule mass spectrometric imaging.

    PubMed

    Gemperline, Erin; Rawson, Stephanie; Li, Lingjun

    2014-10-21

    The matrix application technique is critical to the success of a matrix-assisted laser desorption/ionization (MALDI) experiment. This work presents a systematic study aiming to evaluate three different matrix application techniques for MALDI mass spectrometric imaging (MSI) of endogenous metabolites from legume plant, Medicago truncatula, root nodules. Airbrush, automatic sprayer, and sublimation matrix application methods were optimized individually for detection of metabolites in the positive ionization mode exploiting the two most widely used MALDI matrices, 2,5-dihydroxybenzoic acid (DHB) and α-cyano-4-hydroxycinnamic acid (CHCA). Analytical reproducibility and analyte diffusion were examined and compared side-by-side for each method. When using DHB, the optimized method developed for the automatic matrix sprayer system resulted in approximately double the number of metabolites detected when compared to sublimation and airbrush. The automatic sprayer method also showed more reproducible results and less analyte diffusion than the airbrush method. Sublimation matrix deposition yielded high spatial resolution and reproducibility but fewer analytes in the higher m/z range (500-1000 m/z). When the samples were placed in a humidity chamber after sublimation, there was enhanced detection of higher mass metabolites but increased analyte diffusion in the lower mass range. When using CHCA, the optimized automatic sprayer method and humidified sublimation method resulted in double the number of metabolites detected compared to standard airbrush method.

  10. Study of solid propellant flame structure by mass-spectrometric sampling, including MBMS

    SciTech Connect

    Korobeinichev, O.P.; Kuibida, L.V.; Paletskii, A.A.

    1995-03-01

    At present the most effective and universal experimental technique for studying the condensed systems (including solid propellants) flame structure is the method of mass-spectrometric probing of condensed system (CS) flames (MSPCSF) which was improved in the authors laboratory in 1975. It allows to record all stable species present in the flame as well as the structure of CS flame with the resolution sufficient to study CS combustion at low pressures. The use of spectroscopic methods requires certain parameters which are not available. The MSPCSF method consists in the following: a burning stand of solid propellant moves with a speed exceeding the burning rate towards the probe so that the probe is sampling continuously the gaseous species from all the zones including those adjacent to the burning surface. The sample is transported to the ion source of a time-of-flight (TOF) or quadrupole (QMS) mass-spectrometer. The mass spectra of samples are recorded with simultaneous filming of the probe and burning surface. The data allow one to identify stable components, to determine their concentrations and spatial distributions, i.e. to study the flame microstructure.

  11. Mass spectrometric measurement of protein amide hydrogen exchange rates of apo- and holo-myoglobin.

    PubMed Central

    Johnson, R. S.; Walsh, K. A.

    1994-01-01

    Measurement of backbone amide hydrogen exchange rates can provide detailed information concerning protein structure, dynamics, and interactions. Although nuclear magnetic resonance is typically used to provide these data, its use is restricted to lower molecular weight proteins that are soluble at millimolar concentrations. Not subject to these limitations is a mass spectrometric approach for measuring deuterium incorporation into proteins that are subsequently proteolyzed by pepsin; the resulting peptide masses are measured using a flowing-fast atom bombardment ionization source (Zhang Z, Smith DL, 1993, Protein Sci 2:522-531). In the current study, amide deuterium incorporation for intact apo- and holo-myoglobin was measured using liquid chromatography coupled directly to an electrospray ionization (LC/MS) source. Electrospray ionization provided a more complete coverage of the protein sequence and permitted the measurement of deuterium incorporation into intact proteins. Tandem mass spectrometry was used to rapidly identify the peptic peptides. It was found that within 30 s, the amides in apo-myoglobin were 47% deuterated, whereas holo-myoglobin was 12% deuterated. Peptic digestion and LC/MS demonstrated that regions represented by peptic peptides encompassing positions 1-7, 12-29, and 110-134 were not significantly altered by removal of the heme. Likewise, destabilized regions were identified within positions 33-106 and 138-153. PMID:7756994

  12. Use of mass spectrometric methods for field screening of VOC`s

    SciTech Connect

    Evans, J.C.

    1994-11-01

    While mass spectrometric (MS) methods of chemical analysis, particularly gas chromatography-mass spectrometry (GC/MS), have been the mainstay of environmental organic analytical techniques in the laboratory through the use of EPA and other standard methods, field implementation is relatively rare. Instrumentation and methods now exist for utilizing MS and GC/MS techniques in the field for analysis of VOC`s in gas phase, aqueous, and soil media. Examples of field investigations utilizing HP 5971A and Viking SpectraTrak systems for analysis of VOC`s in all three media will be presented. Mass spectral methods were found to offer significant advantages in terms of speed of analysis and reliability of compound identification over field gas chromatography (GC) methods while preserving adequate levels of detection sensitivity. The soil method in particular provides a method for rapid in-field analysis of methanol preserved samples thus minimizing the problem of volatiles loss which typically occurs with routine use of the EPA methods and remote analysis. The high cost of MS instrumentation remains a major obstacle to more widespread use.

  13. Targeting prohibited substances in doping control blood samples by means of chromatographic-mass spectrometric methods.

    PubMed

    Thevis, Mario; Thomas, Andreas; Schänzer, Wilhelm

    2013-12-01

    Urine samples have been the predominant matrix for doping controls for several decades. However, owing to the complementary information provided by blood (as well as serum or plasma and dried blood spots (DBS)), the benefits of its analysis have resulted in continuously increasing appreciation by anti-doping authorities. On the one hand, blood samples allow for the detection of various different methods of blood doping and the abuse of erythropoiesis-stimulating agents (ESAs) via the Athlete Biological Passport; on the other hand, targeted and non-targeted drug detection by means of chromatographic-mass spectrometric methods represents an important tool to increase doping control frequencies out-of-competition and to determine drug concentrations particularly in in-competition scenarios. Moreover, blood analysis seldom requires in-depth knowledge of drug metabolism, and the intact substance rather than potentially unknown or assumed metabolic products can be targeted. In this review, the recent developments in human sports drug testing concerning mass spectrometry-based techniques for qualitative and quantitative analyses of therapeutics and emerging drug candidates are summarized and reviewed. The analytical methods include both low and high molecular mass compounds (e.g., anabolic agents, stimulants, metabolic modulators, peptide hormones, and small interfering RNA (siRNA)) determined from serum, plasma, and DBS using state-of-the-art instrumentation such as liquid chromatography (LC)-high resolution/high accuracy (tandem) mass spectrometry (LC-HRMS), LC-low resolution tandem mass spectrometry (LC-MS/MS), and gas chromatography-mass spectrometry (GC-MS).

  14. Tandem mass spectrometric analysis of novel peptide-modified gemini surfactants used as gene delivery vectors.

    PubMed

    Al-Dulaymi, M; El-Aneed, A

    2017-06-01

    Diquaternary ammonium gemini surfactants have emerged as effective gene delivery vectors. A novel series of 11 peptide-modified compounds was synthesized, showing promising results in delivering genetic materials. The purpose of this work is to elucidate the tandem mass spectrometric (MS/MS) dissociation behavior of these novel molecules establishing a generalized MS/MS fingerprint. Exact mass measurements were achieved using a hybrid quadrupole orthogonal time-of-flight mass spectrometer, and a multi-stage MS/MS analysis was conducted using a triple quadrupole-linear ion trap mass spectrometer. Both instruments were operated in the positive ionization mode and are equipped with electrospray ionization. Abundant triply charged [M+H](3+) species were observed in the single-stage analysis of all the evaluated compounds with mass accuracies of less than 8 ppm in mass error. MS/MS analysis showed that the evaluated gemini surfactants exhibited peptide-related dissociation characteristics because of the presence of amino acids within the compounds' spacer region. In particular, diagnostic product ions were originated from the neutral loss of ammonia from the amino acids' side chain resulting in the formation of pipecolic acid at the N-terminus part of the gemini surfactants. In addition, a charge-directed amide bond cleavage was initiated by the amino acids' side chain producing a protonated α-amino-ε-caprolactam ion and its complimentary C-terminus ion that contains quaternary amines. MS/MS and MS(3) analysis revealed common fragmentation behavior among all tested compounds, resulting in the production of a universal MS/MS fragmentation pathway. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  15. Functional expression, purification and high sequence coverage mass spectrometric characterization of human excitatory amino acid transporter EAAT2

    PubMed Central

    Ye, Ran; Rhoderick, Joseph F.; Thompson, Charles M.; Bridges, Richard J.

    2015-01-01

    The glial excitatory amino acid transporter 2 (EAAT2) mediates a majority of glutamate re-uptake in human CNS and, consequently, is associated with a variety of signaling and pathological processes. While our understanding of the function, mechanism and structure of this integral membrane protein is increasing, little if any mass spectrometric (MS) data is available for any of the EAATs specifically, and for only a few mammalian plasma membrane transporters in general. A protocol to express and purify functional EAAT2 in sufficient quantities to carry out MS-based peptide mapping as needed to study ligand–transporter interactions is described. A 6×HIS epitope was incorporated into the N-terminus of human EAAT2. The recombinant protein was expressed in high levels in mammalian HEK 293T cells, where it exhibited the pharmacological properties of the native transporter. EAAT2 was purified from isolated cell membranes in a single step using nickel affinity chromatography. In-gel and in-solution trypsin digestions were conducted on the isolated protein and then analyzed by MALDI-TOF and LC-MS/MS mass spectrometry. Overall, 89% sequence coverage of the protein was achieved with these methods. In particular, an 88 amino acid tryptic peptide covering the presumed substrate binding domains HP1, TMD7, HP2, and TMD8 domains of EAAT2 was also identified after N-deglycosylation. Beyond the specific applicability to EAAT2, this study provides an efficient, simple and scalable approach to express, purify, digest and characterize integral membrane transporter proteins by mass spectrometry. PMID:20399272

  16. Mass spectrometric identification of phospholipids in human tears and tear lipocalin.

    PubMed

    Dean, Austin W; Glasgow, Ben J

    2012-04-02

    The purpose of this article was to identify by mass spectrometry phosphocholine lipids in stimulated human tears and determine the molecules bound to tear lipocalin or other proteins. Tear proteins were separated isocratically from pooled stimulated human tears by gel filtration fast performance liquid chromatography. Separation of tear lipocalin was confirmed by SDS tricine gradient PAGE. Protein fractions were extracted with chloroform/methanol and analyzed with electrospray ionization MS/MS triple quadrupole mass spectrometry in precursor ion scan mode for select leaving groups. For quantification, integrated ion counts were derived from standard curves of authentic compounds of phosphatidylcholine (PC) and phosphatidylserine. Linear approximation was possible from integration of the mass spectrometrically obtained ion peaks at 760 Da for the PC standard. Tears contained 194 ng/mL of the major intact PC (34:2), m/z 758.6. Ten other monoisotopic phosphocholines were found in tears. A peak at 703.3 Da was assigned as a sphingomyelin. Four lysophosphatidylcholines (m/z 490-540) accounted for about 80% of the total integrated ion count. The [M+H](+) compound, m/z 496.3, accounted for 60% of the signal intensity. Only the tear lipocalin-bearing fractions showed phosphocholines (104 ng/mL). Although the intact phospholipids bound to tear lipocalin corresponded precisely in mass and relative signal intensity to that found in tears, we did not identify phosphocholines between m/z 490 and 540 in any of the gel-filtration fractions. Phospholipids, predominantly lysophospholipids, are present in tears. The higher mass intact PCs in tears are native ligands of tear lipocalin.

  17. Mass Spectrometric Identification of Phospholipids in Human Tears and Tear Lipocalin

    PubMed Central

    Dean, Austin W.; Glasgow, Ben J.

    2012-01-01

    Purpose. The purpose of this article was to identify by mass spectrometry phosphocholine lipids in stimulated human tears and determine the molecules bound to tear lipocalin or other proteins. Methods. Tear proteins were separated isocratically from pooled stimulated human tears by gel filtration fast performance liquid chromatography. Separation of tear lipocalin was confirmed by SDS tricine gradient PAGE. Protein fractions were extracted with chloroform/methanol and analyzed with electrospray ionization MS/MS triple quadrupole mass spectrometry in precursor ion scan mode for select leaving groups. For quantification, integrated ion counts were derived from standard curves of authentic compounds of phosphatidylcholine (PC) and phosphatidylserine. Results. Linear approximation was possible from integration of the mass spectrometrically obtained ion peaks at 760 Da for the PC standard. Tears contained 194 ng/mL of the major intact PC (34:2), m/z 758.6. Ten other monoisotopic phosphocholines were found in tears. A peak at 703.3 Da was assigned as a sphingomyelin. Four lysophosphatidylcholines (m/z 490–540) accounted for about 80% of the total integrated ion count. The [M+H]+ compound, m/z 496.3, accounted for 60% of the signal intensity. Only the tear lipocalin–bearing fractions showed phosphocholines (104 ng/mL). Although the intact phospholipids bound to tear lipocalin corresponded precisely in mass and relative signal intensity to that found in tears, we did not identify phosphocholines between m/z 490 and 540 in any of the gel-filtration fractions. Conclusions. Phospholipids, predominantly lysophospholipids, are present in tears. The higher mass intact PCs in tears are native ligands of tear lipocalin. PMID:22395887

  18. Identification of Bremia lactucae and Oidium neolycopersici proteins extracted for intact spore MALDI mass spectrometric biotyping.

    PubMed

    Beinhauer, Jana; Lenobel, René; Loginov, Dmitry; Chamrád, Ivo; Řehulka, Pavel; Sedlářová, Michaela; Marchetti-Deschmann, Martina; Allmaier, Günter; Šebela, Marek

    2016-11-01

    Several proteomic approaches were applied to identify protein markers providing typical signals during intact cell/spore (IC/IS) MALDI-TOF MS of two plant pathogens, namely Bremia lactucae (a downy mildew) and Oidium neolycopersici (a powdery mildew). First, proteins were extracted from intact spores of the microorganisms under conditions simulating their treatment prior to the mass spectrometric analysis. After a separation by electrophoresis and tryptic digestion, 198 and 140 proteins were identified in the B. lactucae and O. neolycopersici extracts, respectively. A large portion of them were found to be involved in the process of protein biosynthesis. For the first time, some proteins were assigned to characteristic signals in MS profiles of the investigated pathogens based on an agreement in the molecular mass. There were 9 and 10 proteins recognized, respectively, which could contribute significantly to the spectral patterns. These proteins were assigned tentatively to the following peaks in the MS profiles: (i) m/z 7828; 8593; 10 456; 11 312; 12 450; 12 763; 14 756 and 16 854 for B. lactucae; (ii) m/z 7709; 8895; 9504; 9952; 11 317; 14 082 and 14 839 for O. neolycopersici. We demonstrated the presence of ribosomal proteins and histones, which could be employed as markers in biotyping analyses for pathogen identification. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Mass spectrometric characterization of limited proteolysis activity in human plasma samples under mild acidic conditions.

    PubMed

    Yang, Jingzhi; Röwer, Claudia; Koy, Cornelia; Ruß, Manuela; Rüger, Christopher P; Zimmermann, Ralf; von Fritschen, Uwe; Bredell, Marius; Finke, Juliane C; Glocker, Michael O

    2015-11-01

    We developed a limited proteolysis assay for estimating dynamics in plasma-borne protease activities using MALDI ToF MS analysis as readout. A highly specific limited proteolysis activity was elicited in human plasma by shifting the pH to 6. Mass spectrometry showed that two singly charged ion signals at m/z 2753.44 and m/z 2937.56 significantly increased in abundance under mild acidic conditions as a function of incubation time. For proving that a provoked proteolytic activity in mild acidic solution caused the appearance of the observed peptides, control measurements were performed (i) with pepstatin as protease inhibitor, (ii) with heat-denatured samples, (iii) at pH 1.7, and (iv) at pH 7.5. Mass spectrometric fragmentation analysis showed that the observed peptides encompass the amino acid sequences 1-24 and 1-26 from the N-terminus of human serum albumin. Investigations on peptidase specificities suggest that the two best candidates for the observed serum albumin cleavages are cathepsin D and E. Reproducibility, robustness, and sensitivity prove the potential of the developed limited proteolysis assay to become of clinical importance for estimating dynamics of plasma-borne proteases with respect to associated pathophysiological tissue conditions. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Chromatographic tandam mass spectrometric detection of papaverine and its major metabolites in rat urine

    NASA Astrophysics Data System (ADS)

    Peng, Zhihong; Song, Wei; Han, Fengmei; Chen, Huaixia; Zhu, Mingming; Chen, Yong

    2007-10-01

    A rapid, sensitive and specific liquid chromatographic-electrospray ionization (ESI) tandem ion trap mass spectrometric method has been developed for identification of papaverine and its metabolites in rat urine. Six healthy rats were administrated a single dose (100 mg/kg) of papaverine by oral gavage. The urine were sampled for 0-24 h and purified by using a C18 solid-phase extraction cartridge, then the purified urine samples were separated on a reversed-phase C18 column using methanol/2 mmol/L ammonium acetate (70:30, v/v, adjusted to pH 3.5 with formic acid) as mobile phase and detected by an on-line MS detector. Identification and structural elucidation of the metabolites were performed by comparing their changes in molecular mass ([Delta]m) and full scan MSn spectra with those of the parent drug. The results indicated that there were 14 metabolites in rat urine, such as de-methoxyl, hydroxyl, glucuronide and sulfate conjugated metabolites and so on. All these metabolites were reported for the first time.

  1. Mass Spectrometric Imaging of Red Fluorescent Protein in Breast Tumor Xenografts

    NASA Astrophysics Data System (ADS)

    Chughtai, Kamila; Jiang, Lu; Post, Harm; Winnard, Paul T.; Greenwood, Tiffany R.; Raman, Venu; Bhujwalla, Zaver M.; Heeren, Ron M. A.; Glunde, Kristine

    2013-05-01

    Mass spectrometric imaging (MSI) in combination with electrospray mass spectrometry (ESI-MS) is a powerful technique for visualization and identification of a variety of different biomolecules directly from thin tissue sections. As commonly used tools for molecular reporting, fluorescent proteins are molecular reporter tools that have enabled the elucidation of a multitude of biological pathways and processes. To combine these two approaches, we have performed targeted MS analysis and MALDI-MSI visualization of a tandem dimer (td)Tomato red fluorescent protein, which was expressed exclusively in the hypoxic regions of a breast tumor xenograft model. For the first time, a fluorescent protein has been visualized by both optical microscopy and MALDI-MSI. Visualization of tdTomato by MALDI-MSI directly from breast tumor tissue sections will allow us to simultaneously detect and subsequently identify novel molecules present in hypoxic regions of the tumor. MS and MALDI-MSI of fluorescent proteins, as exemplified in our study, is useful for studies in which the advantages of MS and MSI will benefit from the combination with molecular approaches that use fluorescent proteins as reporters.

  2. Mass Spectrometric Characterization of Benzoxazinoid Glycosides from Rhizopus-Elicited Wheat (Triticum aestivum) Seedlings.

    PubMed

    de Bruijn, Wouter J C; Vincken, Jean-Paul; Duran, Katharina; Gruppen, Harry

    2016-08-17

    Benzoxazinoids function as defense compounds and have been suggested to possess health-promoting effects. In this work, the mass spectrometric behavior of benzoxazinoids from the classes benzoxazin-3-ones (with subclasses lactams, hydroxamic acids, and methyl derivatives) and benzoxazolinones was studied. Wheat seeds were germinated with simultaneous elicitation by Rhizopus. The seedling extract was screened for the presence of benzoxazinoid (glycosides) using reversed-phase ultra-high-performance liquid chromatography with photodiode array detection coupled in line to multiple-stage mass spectrometry (RP-UHPLC-PDA-MS(n)). Benzoxazin-3-ones from the different subclasses showed distinctly different ionization and fragmentation behaviors. These features were incorporated into a newly proposed decision guideline to aid the classification of benzoxazinoids. Glycosides of the methyl derivative 2-hydroxy-4-methoxy-1,4-benzoxazin-3-one were tentatively identified for the first time in wheat. We conclude that wheat seedlings germinated with simultaneous fungal elicitation contain a diverse array of benzoxazinoids, mainly constituted by benzoxazin-3-one glycosides.

  3. Quantitation of dissolved gas content in emulsions and in blood using mass spectrometric detection.

    PubMed

    Grimley, Everett; Turner, Nicole; Newell, Clayton; Simpkins, Cuthbert; Rodriguez, Juan

    2011-06-01

    Quantitation of dissolved gases in blood or in other biological media is essential for understanding the dynamics of metabolic processes. Current detection techniques, while enabling rapid and convenient assessment of dissolved gases, provide only direct information on the partial pressure of gases dissolved in the aqueous fraction of the fluid. The more relevant quantity known as gas content, which refers to the total amount of the gas in all fractions of the sample, can be inferred from those partial pressures, but only indirectly through mathematical modeling. Here we describe a simple mass spectrometric technique for rapid and direct quantitation of gas content for a wide range of gases. The technique is based on a mass spectrometer detector that continuously monitors gases that are rapidly extracted from samples injected into a purge vessel. The accuracy and sample processing speed of the system is demonstrated with experiments that reproduce within minutes literature values for the solubility of various gases in water. The capability of the technique is further demonstrated through accurate determination of O(2) content in a lipid emulsion and in whole blood, using as little as 20 μL of sample. The approach to gas content quantitation described here should greatly expand the range of animals and conditions that may be used in studies of metabolic gas exchange, and facilitate the development of artificial oxygen carriers and resuscitation fluids. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Quantitation of dissolved gas content in emulsions and in blood using mass spectrometric detection

    PubMed Central

    Grimley, Everett; Turner, Nicole; Newell, Clayton; Simpkins, Cuthbert; Rodriguez, Juan

    2011-01-01

    Quantitation of dissolved gases in blood or in other biological media is essential for understanding the dynamics of metabolic processes. Current detection techniques, while enabling rapid and convenient assessment of dissolved gases, provide only direct information on the partial pressure of gases dissolved in the aqueous fraction of the fluid. The more relevant quantity known as gas content, which refers to the total amount of the gas in all fractions of the sample, can be inferred from those partial pressures, but only indirectly through mathematical modeling. Here we describe a simple mass spectrometric technique for rapid and direct quantitation of gas content for a wide range of gases. The technique is based on a mass spectrometer detector that continuously monitors gases that are rapidly extracted from samples injected into a purge vessel. The accuracy and sample processing speed of the system is demonstrated with experiments that reproduce within minutes literature values for the solubility of various gases in water. The capability of the technique is further demonstrated through accurate determination of O2 content in a lipid emulsion and in whole blood, using as little as 20 μL of sample. The approach to gas content quantitation described here should greatly expand the range of animals and conditions that may be used in studies of metabolic gas exchange, and facilitate the development of artificial oxygen carriers and resuscitation fluids. PMID:21497566

  5. Mass Spectrometric Study on Sodium Ion Induced Central Nucleotide Deletion in the Gas Phase

    NASA Astrophysics Data System (ADS)

    Flosadóttir, Helga Dögg; Gíslason, Kristmann; Sigurdsson, Snorri Thor; Ingólfsson, Oddur

    2012-04-01

    We report a mass spectrometric study on sodium ion induced central nucleotide deletion from protonated oligonucleotides (ONTs) and the concurrent recombination of the terminal nucleotides. To shed some light on the mechanism behind this intriguing fragmentation channel, we have studied the metastable decay of a number of different protonated hexameric and octameric oligonucleotides with 0-6 and 0-8 of their exchangeable protons replaced with sodium ions, respectively. In selected cases, we have also studied the further fragmentation of the parent ions after initial base loss. Our findings are concurrent with a reaction mechanism where the initial step is the elimination of a protonated, high proton affinity (PA) base from the center of the ONTs. This is followed by an elimination of a (next neighbour) nucleotide that contains a second high PA base and the concurrent recombination of the terminal nucleotides. To our knowledge, such central nucleotide deletion in the gas phase has only been reported in one previous study (Flosadóttir et al., J. Am. Soc. Mass Spectrom 20:689-696, 2009), and this is the first systematic approach to understand the mechanism behind this channel.

  6. The usefulness of hydrazine derivatives for mass spectrometric analysis of carbohydrates.

    PubMed

    Lattová, Erika; Perreault, Hélène

    2013-01-01

    Over the last years, extensive studies have evaluated glycans from different biological samples and validated the importance of glycosylation as one of the most important post-translational modifications of proteins. Although a number of new methods for carbohydrate analysis have been published and there has been significant progress in their identification, the development of new approaches to study these biomolecules and understand their role in living systems are still vivid challenges that intrigue glycobiologists. In the last decade, the success in analyses of oligosaccharides has been driven mainly by the development of innovative, highly sensitive mass spectrometry techniques. For enhanced mass spectrometry detection, carbohydrate molecules are often derivatized. Besides, the type of labeling can influence the fragmentation pattern and make the structural analysis less complicated. In this regard, in 2003 we introduced the low scale, simple non-reductive tagging of glycans employing phenylhydrazine (PHN) as the derivatizing reagent. PHN-labeled glycans showed increased detection and as reported previously they can be analyzed by HPLC, ESI, or MALDI immediately after derivatization. Under tandem mass spectrometry conditions, PHN-derivatives produced useful data for the structural elucidation of oligosaccharides. This approach of analysis has helped to reveal new isomeric structures for glycans of known/unknown composition and has been successfully applied for the profiling of N-glycans obtained from serum samples and cancer cells. The efficacy of this labeling has also been evaluated for different substituted hydrazine reagents. This review summarizes all types of reducing-end labeling based on hydrazone-linkage that have been used for mass spectrometric analyses of oligosaccharides. This review is also aimed at correcting some past misconceptions or interpretations reported in the literature. © 2013 Wiley Periodicals, Inc.

  7. Mass spectrometric identification of an azobenzene derivative produced by smectite-catalyzed conversion of 3-amino-4-hydroxyphenylarsonic acid

    USGS Publications Warehouse

    Wershaw, R. L.; Rutherford, D.W.; Rostad, C.E.; Garbarino, J.R.; Ferrer, I.; Kennedy, K.R.; Momplaisir, G.-M.; Grange, A.

    2003-01-01

    The compound 3-amino-4-hydroxyphenylarsonic acid (3-amino-HPAA) reacts with smectite to form a soluble azobenzene arsonic acid compound. This reaction is of particular interest because it provides a possible mechanism for the formation of a new type of arsenic compound in natural water systems. 3-Amino-HPAA is a degradation product excreted by chickens that are fed rations amended with roxarsone. Roxarsone is used to control coccidial intestinal parasites in most of the broiler chickens grown in the United States. The structure of the azobenzene arsonic acid compound was first inferred from negative-ion and positive-ion low-resolution mass-spectrometric analyses of the supernatant of the smectite suspension. Elemental composition of the parent ion determined by high-resolution positive-ion mass spectrometric measurements was consistent with the proposed structure of the azobenzene arsonic acid compound. Published by Elsevier Science B.V.

  8. Analytical strategies for the direct mass spectrometric analysis of steroid and corticosteroid phase II metabolites.

    PubMed

    Antignac, Jean-Philippe; Brosseaud, Aline; Gaudin-Hirret, Isabelle; André, François; Bizec, Bruno Le

    2005-03-01

    The use of steroid hormones as growth promoters remains illegal in Europe. A classical approach used to control their utilization consists to measure the parent drug in target biological matrices. However, this strategy may fail when the parent drug is submitted to extensive metabolism reactions. For urine and tissue samples, chemical or enzymatic hydrolysis is usually applied in order to deconjugate glucuronide and sulfate phase II metabolites. But this treatment lead to the loss of information such as nature and relative proportions of the different conjugated forms, which can be useful, for example, to discriminate an endogenous production from an exogenous administration for natural hormones, or for other clinical or biochemical specific applications. For these purposes, direct measurement of conjugated metabolites using liquid chromatography-tandem mass spectrometry may represent a solution of choice. In this context, the mass spectrometric behavior of 14 steroid and corticosteroid phase II metabolites after electrospray ionization was investigated. Their fragmentation pathways in tandem mass spectrometry revealed some specificities within the different group of conjugates. A specific acquisition program (MRM mode) was developed for the unambiguous identification of the studied reference compounds. A more generic method (Parent Scan mode) was also developed for fishing approaches consisting to monitor several fragment ions typical of each conjugate class. A reverse phase HPLC procedure was also proposed for efficient retention and separation of the studied compounds. Finally, a protocol based on quaternary amine SPE was developed, permitting the separation of free, glucuronide, and sulfate fractions. Preliminary results on biological samples demonstrated the suitability of this analytical strategy for direct measurement of dexamethasone glucuronide and sulfate residues in bovine urine.

  9. Dependence of mass spectrometric fragmentation on the bromine substitution pattern of polybrominated diphenyl ethers.

    PubMed

    Wei, Hua; Zhang, Siyu; Wang, Yawei; Wang, Ying; Li, An; Negrusz, Adam; Yu, Gang

    2014-06-01

    This study investigates the link between the bromine substitution and the mass spectrometric fragmentation of polybrominated diphenyl ethers (PBDEs). The mass spectra of 180 PBDEs were obtained in both electron impact (EI) and electron capture negative ionization (ECNI) modes using a single quadrupole mass spectrometer (MS) as well as EI using a tandem MS (MS/MS). The major ions are M(+), [M-2Br](+), [M-2Br](2+) and [M-nBr-28](+) in EI, and Br(-), [HBr2](-) and [C6BrnO](-) in ECNI. In EI-MS, congeners without ortho bromine or having 2,3 substitution on one ring and no ortho bromines on the other were more robust than the others in each homolog. These congeners generated low [M-2Br](+) but relatively high [M-2Br](2+) in EI-MS and negligible [HBr2](-) in ECNI-MS. In EI-MS/MS, the molecular ions of these congeners required higher collision energy to debrominate, and produced additional ions of [M-nBr](+) and [M-nBr-28](+). Full ortho substitution promotes C-O cleavage forming [C6BrnO](-) in ECNI for congeners with >5 bromines. The relationship between the abundance of M(+) and collision energy of the EI-MS/MS was well characterized with a logistic regression model. Principle component analysis found associations between the inflection point collision energy and a few molecular descriptors. Quantum chemistry simulations revealed different EI-induced fragmentation mechanisms among four dibrominated congeners, supporting the hypothesized formation of a stable dibenzofuran-like intermediate during the fragmentation of some congeners but not of others.

  10. Chemical Nature Of Titan’s Organic Aerosols Constrained from Spectroscopic and Mass Spectrometric Observations

    NASA Astrophysics Data System (ADS)

    Imanaka, Hiroshi; Cruikshank, D. P.

    2012-10-01

    The Cassini-Huygens observations greately extend our knowledge about Titan’s organic aerosols. The Cassini INMS and CAPS observations clearly demonstrate the formation of large organic molecules in the ionosphere [1, 2]. The VIMS and CIRS instruments have revealed spectral features of the haze covering the mid-IR and far-IR wavelengths [3, 4, 5, 6]. This study attempts to speculate the possible chemical nature of Titan’s aerosols by comparing the currently available observations with our laboratory study. We have conducted a series of cold plasma experiment to investigate the mass spectrometric and spectroscopic properties of laboratory aerosol analogs [7, 8]. Titan tholins and C2H2 plasma polymer are generated with cold plasma irradiations of N2/CH4 and C2H2, respectively. Laser desorption mass spectrum of the C2H2 plasma polymer shows a reasonable match with the CAPS positive ion mass spectrum. Furthermore, spectroscopic features of the the C2H2 plasma polymer in mid-IR and far-IR wavelegths qualitatively show reasonable match with the VIMS and CIRS observations. These results support that the C2H2 plasma polymer is a good candidate material for Titan’s aerosol particles at the altitudes sampled by the observations. We acknowledge funding supports from the NASA Cassini Data Analysis Program, NNX10AF08G, and from the NASA Exobiology Program, NNX09AM95G, and the Cassini Project. [1] Waite et al. (2007) Science 316, 870-875. [2] Crary et al. (2009) Planet. Space Sci. 57, 1847-1856. [3] Bellucci et al. (2009) Icarus 201, 198-216. [4] Anderson and Samuelson (2011) Icarus 212, 762-778. [5] Vinatier et al. (2010) Icarus 210, 852-866. [6] Vinatier et al. (2012) Icarus 219, 5-12. [7] Imanaka et al. (2004) Icarus 168, 344-366. [8] Imanaka et al. (2012) Icarus 218, 247-261.

  11. Nucleation particles in diesel exhaust: composition inferred from in situ mass spectrometric analysis.

    PubMed

    Schneider, J; Hock, N; Weimer, S; Borrmann, S; Kirchner, U; Vogt, R; Scheer, V

    2005-08-15

    Mass spectrometric measurements of size and composition of diesel exhaust particles have been performed under various conditions: chassis dynamometer tests, field measurements near a German motorway, and individual car chasing. Nucleation particles consisting of volatile sulfate and organic material could be detected both at the chassis dynamometer test facility and during individual car chasing. We found evidence that if nucleation occurs, sulfuric acid/water is the nucleating agent. Low-volatile organics species condense only on the preexisting sulfuric acid/water clusters. Nucleation was found to depend strongly on various parameters such as exhaust dilution conditions, fuel sulfur content, and engine load. The latter determines the fraction of the fuel sulfur that is converted to sulfuric acid. The organic compounds (volatile and low-volatile) condense only on preexisting particles, such as both sulfuric acid nucleation particles and larger accumulation mode soot particles. On the latter, sulfuric acid also condenses, if the conditions for nucleation are not given. The overall ratio of sulfate to organic (volatile and low-volatile) is also strongly dependent on the engine load. It was found that the production of nucleation particles even at high engine load can be suppressed by using low-sulfur fuel.

  12. A mass spectrometric method for quantifying C3 and C6 phosphorylation of starch.

    PubMed

    Carpenter, Margaret; Joyce, Nigel; Butler, Ruth; Genet, Russell; Timmerman-Vaughan, Gail

    2012-12-15

    The glucosyl residues comprising starch can be phosphorylated at either the C3 or the C6 position of the molecule because of the activities of two distinct dikinase enzymes. After hydrolysis of the starch, the C6 phosphorylation is easy to measure using a routine enzyme assay for glucose 6-phosphate, but the C3 phosphorylation is more difficult to assay. A mass spectrometric (MS) method has been developed that, in a single run, can distinguish and quantify the glucose 3-phosphate and glucose 6-phosphate produced by hydrolysis of starch and can also measure the glucose content to give an accurate estimate of the starting material. The MS method involves quantification by LC/MS with external standards, using normal-phase hydrophilic interaction liquid chromatography and selective reaction monitoring. The MS method has been used to determine degrees of starch phosphorylation in a diverse group of potato lines, revealing threefold differences in phosphorylation between high- and low-phosphate lines. The method was also used to show that cold storage of potato tubers for up to 24weeks had little substantive effect on the levels of starch phosphorylation. MS provided an effective and efficient means of determining both the C6 and the C3 phosphorylation of starch.

  13. A fast sampling device for the mass spectrometric analysis of liquid rocket engine exhaust

    NASA Technical Reports Server (NTRS)

    Ryason, P. R.

    1975-01-01

    The design of a device to obtain compositional data on rocket exhaust by direct sampling of reactive flow exhausts into a mass spectrometer is presented. Sampling at three stages differing in pressure and orifice angle and diameter is possible. Results of calibration with pure gases and gas mixtures are erratic and of unknown accuracy for H2, limiting the usefulness of the apparatus for determining oxidizer/fuel ratios from combustion product analysis. Deposition effects are discussed, and data obtained from rocket exhaust spectra are analyzed to give O/F ratios and mixture ratio distribution. The O/F ratio determined spectrometrically is insufficiently accurate for quantitative comparison with cold flow data. However, a criterion for operating conditions with improved mixing of fuel and oxidizer which is consistent with cold flow results may be obtained by inspection of contour plots. A chemical inefficiency in the combustion process when oxidizer is in excess is observed from reactive flow measurements. Present results were obtained with N2O4/N2H4 propellants.

  14. Precise timing of the last interglacial period from mass spectrometric determination of thorium-230 in corals

    NASA Technical Reports Server (NTRS)

    Chen, J. H.; Wasserburg, G. J.; Ku, T.-L.; Edwards, R. Lawrence

    1987-01-01

    The development of mass spectrometric techniques for determination of Th-230 abundance has made it possible to reduce analytical errors in (U-238)-(U-234)-(Th-230) dating of corals even with very small samples. Samples of 6 x 10 to the 8th atoms of Th-230 can be measured to an accuracy of + or - 3 percent (2sigma), and 3 x 10 to the 10th atoms of Th-230 can be measured to an accuracy of + or - 0.2 percent. The time range over which useful age data on corals can be obtained now ranges from about 50 to about 500,000 years. For young corals, this approach may be preferable to C-14 dating. The precision with which the age of a coral can now be determined should make it possible to critically test the Milankovitch hypothesis concerning Pleistocene climate fluctuations. Analyses of a number of corals that grew during the last interglacial period yield ages of 122,000 to 130,000 years. The ages coincide with, or slightly post-date, the summer solar insolation high at 65 deg N latitude which occurred 128,000 years ago. This supports the idea that changes in Pleistocene climate can be the result of variations in the distribution of solar insolation caused by changes in the geometry of the earth's orbit and rotation axis.

  15. Mass Spectrometric and Spectrofluorometric Studies of the Interaction of Aristolochic Acids with Proteins

    NASA Astrophysics Data System (ADS)

    Li, Weiwei; Hu, Qin; Chan, Wan

    2015-10-01

    Aristolochic acid (AA) is a potent carcinogen and nephrotoxin and is associated with the development of “Chinese herb nephropathy” and Balkan endemic nephropathy. Despite decades of research, the specific mechanism of the observed nephrotoxicity has remained elusive and the potential effects on proteins due to the observed toxicity of AA are not well-understood. To better understand the pharmacotoxicological features of AA, we investigated the non-covalent interactions of AA with proteins. The protein-binding properties of AA with bovine serum albumin (BSA) and lysozyme were characterized using spectrofluorometric and mass spectrometric (MS) techniques. Moreover, the protein-AA complexes were clearly identified by high-resolution MS analyses. To the best of our knowledge, this is the first direct evidence of non-covalently bound protein-AA complexes. An analysis of the spectrofluorometric data by a modified Stern-Volmer plot model also revealed that both aristolochic acid I (AAI) and aristolochic acid II (AAII) were bound to BSA and lysozyme in 1:1 stoichiometries. A significantly stronger protein binding property was observed in AAII than in AAI as evidenced by the spectrofluorometric and MS analyses, which may explain the observed higher mutagenicity of AAII.

  16. Mass spectrometric identification of boric acid in fluid inclusions in pegmatite minerals

    SciTech Connect

    Williams, A.E.; Taylor, M.C.

    1996-09-01

    Direct, on-line mass spectrometric analyses were performed on volatiles released from microscopic fluid inclusions in quartz, feldspar, and tourmaline from the miarolitic Belo Horizonte No. 1 pegmatite in the San Jacinto district, and Himalaya pegmatite dike system in the Mesa Grande district of southern California. These analyses are the first inclusion volatile studies to indicate the presence of significant and variable concentrations of B compounds in pegmatite formation fluids. Boron appears as boric acid B(OH){sub 3}, which is found at levels ranging from less than detection limit (<10{sup {minus}7} mole fraction) to as high as 10{sup {minus}4} mole fraction. High B concentrations are seen in inclusion fluids from miarolite filling quartz, cleavelandite variety albite feldspar, and schorl tourmaline from the Belo Horizonte No. 1, while negligible amounts appear in late-stage green/pink-zoned gem elbaite tourmalines from that mine. Fluid inclusions in quartz, as well as grey and pink tourmaline form the miarolites in the Himalaya mine, have undetectable levels of B compounds. In addition to confirming the presence of very high boric acid concentrations in some pegmatite forming solutions, observations of large variations in abundance may provide new constraints on fluid chemical evolution trends during the genesis of these regionally and paragenetically complex gem deposits. 38 refs., 6 figs., 1 tab.

  17. Analysis of Endocrine Disrupting Pesticides by Capillary GC with Mass Spectrometric Detection

    PubMed Central

    Matisová, Eva; Hrouzková, Svetlana

    2012-01-01

    Endocrine disrupting chemicals, among them many pesticides, alter the normal functioning of the endocrine system of both wildlife and humans at very low concentration levels. Therefore, the importance of method development for their analysis in food and the environment is increasing. This also covers contributions in the field of ultra-trace analysis of multicomponent mixtures of organic pollutants in complex matrices. With this fact conventional capillary gas chromatography (CGC) and fast CGC with mass spectrometric detection (MS) has acquired a real importance in the analysis of endocrine disrupting pesticide (EDP) residues. This paper provides an overview of GC methods, including sample preparation steps, for analysis of EDPs in a variety of matrices at ultra-trace concentration levels. Emphasis is put on separation method, mode of MS detection and ionization and obtained limits of detection and quantification. Analysis time is one of the most important aspects that should be considered in the choice of analytical methods for routine analysis. Therefore, the benefits of developed fast GC methods are important. PMID:23202677

  18. Mass spectrometric quantification of salivary metanephrines-A study in healthy subjects.

    PubMed

    Osinga, Thamara E; van der Horst-Schrivers, Anouk N A; van Faassen, Martijn; Kerstens, Michiel N; Dullaart, Robin P F; Pacak, Karel; Links, Thera P; Kema, Ido P

    2016-09-01

    Determination of metanephrine (MN), normetanephrine (NMN), and 3-methoxytyramine (3-MT) in saliva may offer potential diagnostic advantages in diagnosing pheochromocytoma. In this preliminary study, we determined metanephrine concentrations in saliva of healthy subjects and the relationship with simultaneously measured plasma metanephrines. We also studied the possible influence of pre-analytical conditions such as a collection device, awakening, posture, and eating on the salivary metanephrine levels. Eleven healthy subjects were included. Fasting blood and saliva samples were collected in seated position and after 30min of horizontal rest. Plasma and salivary MN, NMN, and 3-MT concentrations were determined using a high-performance liquid chromatography tandem mass spectrometric technique (LC-MS/MS) with automated solid phase extraction sample preparation. Metanephrines were detectable in saliva from all participants both in seated and supine position. No significant correlations were observed between the MN, NMN, and 3-MT concentrations in saliva and plasma in seated or supine position. Furthermore, there was no difference between MN, NMN, and 3-MT samples collected with or without a collection device. Metanephrines can be detected in saliva with LC-MS/MS with sufficient sensitivity and precision. Our findings warrant evaluation of salivary metanephrine measurement as a novel laboratory tool in the work-up of patients suspected of having a pheochromocytoma. Copyright © 2016 The Canadian Society of Clinical Chemists. All rights reserved.

  19. Precise timing of the last interglacial period from mass spectrometric determination of thorium-230 in corals

    SciTech Connect

    Edwards, R.L.; Chen, J.H.; Ku, T.L.; Wasserburg, G.J.

    1987-06-19

    The development of mass spectrometric techniques for determination of STTh abundance has made it possible to reduce analytical errors in STYU-STUU-STTh dating of corals even with very small samples. Samples of 6 x 10Y atoms of STTh can be measured to an accuracy of +/- 3% (2sigma) and 3 x 10 atoms of STTh can be measured to an accuracy of +/- 0.2%. The time range over which useful age data on corals can be obtained now ranges from about 50 to about 500,000 years. For young corals, this approach may be preferable to UC dating. The precision should make it possible to critically test the Milankovitch hypothesis concerning Pleistocene climate fluctuations. Analyses of a number of corals that grew during the last interglacial period yield ages of 122,000 to 130,000 years. The ages coincide with, or slightly postdate, the summer solar insolation high at 65N latitude which occurred 128,000 years ago. This supports the idea that changes in Pleistocene climate can be the result of variations in the distribution of solar insolation caused by changes in the geometry of the earth's orbit and rotation axis.

  20. Liquid chromatography/mass spectrometric determination of patulin in apple juice using atmospheric pressure photoionization.

    PubMed

    Takino, Masahiko; Daishima, Shigeki; Nakahara, Taketoshi

    2003-01-01

    This paper describes a comparison between atmospheric pressure chemical ionization (APCI) and the recently introduced atmospheric pressure photoionization (APPI) technique for the liquid chromatography/mass spectrometric (LC/MS) determination of patulin in clear apple juice. A column switching technique for on-line extraction of clear apple juice was developed. The parameters investigated for the optimization of APPI were the ion source parameters fragmentor voltage, capillary voltage, and vaporizer temperature, and also mobile phase composition and flow rate. Furthermore, chemical noise and signal suppression of analyte signals due to sample matrix interference were investigated for both APCI and APPI. The results indicated that APPI provides lower chemical noise and signal suppression in comparison with APCI. The linear range for patulin in apple juice (correlation coefficient >0.999) was 0.2-100 ng mL(-1). Mean recoveries of patulin in three apple juices ranged from 94.5 to 103.2%, and the limit of detection (S/N = 3), repeatability and reproducibility were 1.03-1.50 ng mL(-1), 3.9-5.1% and 7.3-8.2%, respectively. The total analysis time was 10.0 min.

  1. Quantum dots assisted laser desorption/ionization mass spectrometric detection of carbohydrates: qualitative and quantitative analysis.

    PubMed

    Bibi, Aisha; Ju, Huangxian

    2016-04-01

    A quantum dots (QDs) assisted laser desorption/ionization mass spectrometric (QDA-LDI-MS) strategy was proposed for qualitative and quantitative analysis of a series of carbohydrates. The adsorption of carbohydrates on the modified surface of different QDs as the matrices depended mainly on the formation of hydrogen bonding, which led to higher MS intensity than those with conventional organic matrix. The effects of QDs concentration and sample preparation method were explored for improving the selective ionization process and the detection sensitivity. The proposed approach offered a new dimension to the application of QDs as matrices for MALDI-MS research of carbohydrates. It could be used for quantitative measurement of glucose concentration in human serum with good performance. The QDs served as a matrix showed the advantages of low background, higher sensitivity, convenient sample preparation and excellent stability under vacuum. The QDs assisted LDI-MS approach has promising application to the analysis of carbohydrates in complex biological samples. Copyright © 2016 John Wiley & Sons, Ltd.

  2. Gas chromatographic/mass spectrometric determination of daminozide in high protein food products.

    PubMed

    Conditt, M K; Baumgardner, J R; Hellmann, L M

    1988-01-01

    A gas chromatographic/mass spectrometric (GC/MS) method for determining daminozide in high protein products has been developed. Daminozide is hydrolyzed in the presence of a strong base to form unsymmetrical dimethylhydrazine (UDMH) which is then distilled from the food matrix. A stable derivative is formed by reacting UDMH with salicyladehyde to form salicyaldehyde dimethylhydrazone. This derivative is separated and quantitated by GC/MS using selected ion monitoring (SIM) of key ions in the fragmentation pattern: m/z 164 (molecular ion of hydrazone) and m/z 120 (C7H6ON). An internal standard, 4-nitroanisole, is monitored at m/z 153 (molecular ion) and m/z 123 (C6H5O2N). The limit of detection is 0.01 ppm daminozide in a 50 g sample; however, because of variation at low levels, the limit of quantitation is 0.1 ppm. Recoveries are 90% or greater from peanuts and peanut butter spiked at the 0.1-2 ppm level. Reproducibility of the method depends on the food matrix and is 26% RSD in the worst case. Data are compared for the GC/MS method and the official EPA colorimetric procedure. Results showed a high bias in the colorimetric method, especially when roasted peanut products were analyzed.

  3. Precise timing of the last interglacial period from mass spectrometric determination of thorium-230 in corals.

    PubMed

    Edwards, R L; Chen, J H; Ku, T L; Wasserburg, G J

    1987-06-19

    The development of mass spectrometric techniques for determination of (230)Th abundance has made it possible to reduce analytical errors in (238)U-(234)U-(230)Th dating of corals even with very small samples. Samples of 6 x 10(8) atoms of (230)Th can be measured to an accuracy of +/-3 percent (2sigma) and 3 x 10(10) atoms of (230)Th can be measured to an accuracy of +/-0.2 percent. The time range over which useful age data on corals can be obtained now ranges from about 50 to about 500,000 years. For young corals, this approach may be preferable to (14)C dating. The precision with which the age of a coral can now be determined should make it possible to critically test the Milankovitch hypothesis concerning Pleistocene climate fluctuations. Analyses of a number of corals that grew during the last interglacial period yield ages of 122,000 to 130,000 years. The ages coincide with, or slightly postdate, the summer solar insolation high at 65 degrees N latitude which occurred 128,000 years ago. This supports the idea that changes in Pleistocene climate can be the result of variations in the distribution of solar insolation caused by changes in the geometry of the earth's orbit and rotation axis.

  4. Mass Spectrometric Analysis of Sialylated Glycans Using Solid Phase Labeling of Sialc Acids

    PubMed Central

    Shah, Punit; Yang, Shuang; Sun, Shisheng; Aiyetan, Paul; Yarema, Kevin J.; Zhang, Hui

    2013-01-01

    The analysis of sialylated glycans is critical for understanding the role of sialic acid in normal biological processes as well as in disease. However, the labile nature of sialic acid typically renders routine analysis of this monosaccharide by mass spectrometric methods has been difficult. To overcome this difficulty we pursued derivatization methodologies, extending established acetohydrazide approaches to aniline-based methods, and finally to optimized p-toluidine derivatization. This new quantitative glycoform profiling method using MALDI-TOF in positive ion mode was validated by first comparing N-glycans isolated from fetuin and serum and was then exploited to analyze the effects of increased metabolic flux through the sialic acid pathway in SW1990 pancreatic cancer cells by using a co-labeling strategy with light and heavy toluidine. The latter results established that metabolic flux, in a complementary manner to the more well-known impact of sialyltransferase expression, can critically modulate the sialylation of specific glycans while leaving others virtually unchanged. PMID:23445396

  5. Enantiospecific gas chromatographic-mass spectrometric analysis of urinary methylphenidate: implications for phenotyping.

    PubMed

    LeVasseur, Natalie L; Zhu, Hao-Jie; Markowitz, John S; DeVane, C Lindsay; Patrick, Kennerly S

    2008-02-01

    A chiral derivatization gas chromatographic-mass spectrometric (GC-MS) method for urine methylphenidate (MPH) analysis was developed and validated to investigate preliminary findings regarding a novel MPH poor metabolizer (PM). Detection was by electron impact (EI) ionization-selected ion monitoring of the N-trifluoroacetylprolylpiperidinium fragments from MPH and the piperidine-deuterated MPH internal standard. The PM eliminated approximately 70 times more l-MPH in urine (9% of the dose over 0-10h), and approximately 5 times more of the d-isomer (10% of the dose), than the mean values determined from 10 normal metabolizers of MPH. Only minor amounts of the metabolite p-hydroxy-MPH were found in the urine of both the PM and normal metabolizers, while the concentration of MPH lactam was not high enough to be detectable. The described method indirectly gauges the functional carboxylesterase-1 status of patients receiving MPH based on the evaluation of relative urine concentrations of d-MPH:l-MPH. Clinical implications concerning rational drug selection for an identified or suspected MPH PM are discussed.

  6. Gas chromatography-mass spectrometric method for metabolic profiling of tobacco leaves.

    PubMed

    Li, Yong; Pang, Tao; Li, Yanli; Wang, Xiaolin; Li, Qinghua; Lu, Xin; Xu, Guowang

    2011-06-01

    A gas chromatography-mass spectrometric method was developed for profiling of tobacco leaves. The differentiation among tobacco leaves planted in two different regions was investigated. Prior to analysis, the extraction solvent formulation was optimized and a combination of water, methanol and acetonitrile with a volume ratio of 3:1:1 was found to be optimal. The reproducibility of the method was satisfactory. Kendall tau-b rank correlation coefficients were equal to 1 (p<0.05) for 82% of the resolved peaks (up to 95% of the overall peak areas), indicating the good response correlation. Forty-four compounds including 9 saccharides, 9 alcohols, 9 amino acids, 16 organic acids and phosphoric acid were identified based on standard compounds. The method was successfully applied for profiling of tobacco leaves from Zimbabwe and Yunnan of China. Our result revealed that levels of saccharides and their derivatives including xylose, ribose, fructose, glucose, turanose, xylitol and glyceric acid were more abundant while sucrose, glucitol and D-gluconic acid were less abundant in tobacco leaves from Yunnan as compared to those from Zimbabwe. Amino acids such as L-alanine, L-tyrosine and L-threonine were found to be richer in Zimbabwe tobacco than in Yunnan tobacco.

  7. Electrochemically-Modulated Separation and Mass Spectrometric Analysis of Actinides in Difficult Matrices

    SciTech Connect

    Duckworth, Douglas C.; Liezers, Martin; Lehn, Scott A.; Douglas, Matthew

    2009-01-01

    Electrochemically-modulated separations (EMS) are a straightforward means of isolating and pre-concentrating elements for on-line mass spectrometric analysis. Elements are accumulated at electrochemical working electrodes and subsequently released into a clean carrier solution for spectroscopic analysis. EMS can employ solely aqueous chemistry and uses electrochemical redox adjustment of oxidation state to “trigger” reversible chelation / complexation. Less tractable elements (e.g., uranium and plutonium), based on redox potentials, can therefore be extracted from difficult matrices following redox adjustment and chelation with electrode chelation sites. Simply put, separation is achieved by a small voltage step that is applied to the target electrode to turn “on” or “off” the specific actinide affinity of an electrode. This separation technology employs both redox and chelation chemistry to effect highly selective accumulation of target actinides, and results in element separation, matrix elimination and analyte preconcentration. Prior studies have developed protocols and preliminary insight into EMS processes for U and Pu. U and Pu are released upon oxidation and reduction, respectively, allowing complete separation due to widely divergent redox potentials. T The coupling of EMS on-line with ICP-MS for elemental and isotopic analysis of uranium and plutonium is presented, with a focus on analytical performance metrics and applicability to safeguards and process monitoring via nondestructive analyses.

  8. Determination of ractopamine in pig hair using liquid chromatography with tandem mass spectrometric detection.

    PubMed

    Wu, Junlin; Liu, Xiaoyun; Peng, Yunping

    2014-01-01

    A quantitative analytical procedure for the determination of ractopamine in pig hair has been developed and validated. The hair samples were washed and incubated at 75°C with isoxuprine and hair extraction buffer. The drug present was quantified using mixed solid-phase extraction and liquid chromatography with tandem mass spectrometric detection. The limit of quantization (LOQ) was 10pg/mg and the intra-day precision at 25pg/mg and 750pg/mg was 0.49% and 2.8% respectively. Inter-day precision was 0.88% and 3.52% at the same concentrations. The hair extraction percentage recovery at 25pg/mg and 50ng/mL was 99.47% and 103.83% respectively. The extraction percentage recovery at 25pg/mg and 50ng/mg was 93.52% and 100.26% respectively. Our results showed that ractopamine residues persist in hair in 24days of withdrawal and also showed the possibility to test ractopamine from pig hair samples.

  9. Mass spectrometric identification of isocyanate-induced modifications of keratins in human skin.

    PubMed

    Hulst, Albert G; Verstappen, Daan R W; van der Riet-Van Oeveren, Debora; Vermeulen, Nico P E; Noort, Daan

    2015-07-25

    In the current paper we show that exposure of human callus to isocyanates leads to covalent modifications within keratin proteins. Mass spectrometric analyses of pronase digests of keratin isolated from exposed callus show that both mono- and di-adducts (for di-isocyanates) are predominantly formed on the ε-amino group of lysine. In addition, numerous modified tryptic keratin fragments were identified, demonstrating rather random lysine modification. Interestingly, preliminary experiments demonstrate that in case of MDI a similar lysine di-adduct was formed with lung elastin. Our data support the hypothesis that skin sensitization through antigenic modifications of skin proteins by isocyanates could play a role in occupational isocyanate-induced asthma. It is further envisaged that the elucidated adducts will also have great potential for use as biomarkers to assess skin exposure to isocyanates. Advantageously, the various lysine adducts display the presence of a characteristic daughter fragment at m/z 173.1 [lysine-NCO](+), enabling generic and rapid screening for exposure to isocyanates.

  10. Chromatographic and mass spectrometric techniques in studies on oxidative stress in autism.

    PubMed

    Kałużna-Czaplińska, Joanna; Jóźwik-Pruska, Jagoda

    2016-04-15

    Healthy body is characterized by the presence of a dynamic and balanced equilibrium between the production of reactive oxygen species (ROS) and the antioxidant capacity. In oxidative stress this balance is switched to reactions of oxidation leading to increased production of ROS, exceeding the capacity of physiological antioxidant systems. Oxidative stress is known to be linked to many disturbances, disorders and diseases. One of these is the autism spectrum disorder (ASD). ASD is a neurodevelopmental disorder manifested by abnormalities in social communication and interaction, as well as by occurrence of repetitive, restricted patterns of behavior or activities. It is believed that adequate knowledge about the oxidative stress biomarkers and the possibility of their reliable measuring could be useful in broadening knowledge on various diseases including ASD. A high number of compounds have been proposed as biomarkers of oxidative stress. Some of these are connected with the severity of ASD. The present review gives a summary of the chromatographic techniques used for the determination of biomarkers for oxidative stress in autism, and of other compounds important in this context. The first part of the review focuses on the correlation between oxidative stress and autism. The second part describes applications of chromatographic and mass spectrometric methods to the analysis of different metabolites connected with oxidative stress in biological fluids of autistic children. Advantages as well as disadvantages of the application of these methods for the analysis of different types of oxidative stress biomarkers are discussed.

  11. Precise timing of the last interglacial period from mass spectrometric determination of thorium-230 in corals

    NASA Technical Reports Server (NTRS)

    Chen, J. H.; Wasserburg, G. J.; Ku, T.-L.; Edwards, R. Lawrence

    1987-01-01

    The development of mass spectrometric techniques for determination of Th-230 abundance has made it possible to reduce analytical errors in (U-238)-(U-234)-(Th-230) dating of corals even with very small samples. Samples of 6 x 10 to the 8th atoms of Th-230 can be measured to an accuracy of + or - 3 percent (2sigma), and 3 x 10 to the 10th atoms of Th-230 can be measured to an accuracy of + or - 0.2 percent. The time range over which useful age data on corals can be obtained now ranges from about 50 to about 500,000 years. For young corals, this approach may be preferable to C-14 dating. The precision with which the age of a coral can now be determined should make it possible to critically test the Milankovitch hypothesis concerning Pleistocene climate fluctuations. Analyses of a number of corals that grew during the last interglacial period yield ages of 122,000 to 130,000 years. The ages coincide with, or slightly post-date, the summer solar insolation high at 65 deg N latitude which occurred 128,000 years ago. This supports the idea that changes in Pleistocene climate can be the result of variations in the distribution of solar insolation caused by changes in the geometry of the earth's orbit and rotation axis.

  12. Mass spectrometric study of ammonia/methane surface-wave plasma applied to low-temperature growth of carbon nanomaterials

    NASA Astrophysics Data System (ADS)

    Bekarevich, Raman; Motrescu, Iuliana; Rahachou, Aliaksandr; Nagatsu, Masaaki

    2015-02-01

    We present a mass spectrometric study of NH3/CH4 surface-wave plasma (SWP) used for low-temperature synthesis of carbon nanomaterials (CNMs) with graphite-encapsulated Ni nanoparticles as a catalyst. Optical emission and mass spectra were analysed to understand the processes responsible for CNMs synthesis. We have shown that an optimum balance between etching by atomic hydrogen and CNMs synthesis by carbon-containing molecular species was achieved at a NH3/CH4 ratio of roughly 70/30% in SWP, where the highest number of hydrogen and carbon-containing molecular species in SWP are observed in the optical emission and mass spectrometry measurements.

  13. FT-ICR mass spectrometric and density functional theory studies of sulfate prenucleation clusters

    NASA Astrophysics Data System (ADS)

    Lemke, K. H.

    2012-12-01

    Recent mass spectrometric1 and relaxation spectroscopic studies2 of metal sulfate salts have demonstrated that aqueous clusters play an important role in sulfate prenucleation processes. While such studies provide evidence that that ion clusters are nucleation relevant species, ultra-high resolution mass spectrumetry, in particular, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR/MS) can provide additional valuable information about the molecular composition and stability of individual ion clusters. Prompted by the above studies, our group has begun a systematic survey of metal sulfate clusters using FT-ICR mass spectrometry. Here, I report stoichiometries, structures and thermodynamic properties of calcium sulfate ion clusters, both "dry" and microsolvated, using electrospray ionization FT-ICR mass spectrometry in combination with semi-empirical methods and M062X/aug-cc-PVXZ level density functional theory calculations. In electrosprayed dilute aqueous solutions of CaSO4 (1-20mM), droplet desolvation results in the formation of stable doubly-charged clusters of [Ca(CaSO4)m(H2O)n]+2 (m≤10 & n≤9) as well as larger quadruply-charged ion clusters [Ca2(CaSO4)m(H2O)n]+4 with m≤23 and n≤10, demonstrating considerable sulfate nucleation potential in undersaturated electrolyte solutions. An attempt was also made to assess the extent of ion cluster aggregation in solution prior to electrospray ionization by measuring ion mass spectra at different solution concentrations. In brief, an increase in calcium sulfate concentration from 1-10mM results in a continuous increase in polynuclear ion cluster species, while smaller clusters, for instance, Ca[CaSO4]+2 and corresponding hydrated forms, become increasingly less abundant. Building on semi-empirical methods, M062X calculations have been applied to predict calcium sulfate cluster geometries, both "dry" and microsolvated, as well as the size-dependent evolution of clustering and hydration energies. 1

  14. Mass spectrometric detection of CYP450 adducts following oxidative desulfuration of methyl parathion.

    PubMed

    Kyle, Patrick B; Smith, Stanley V; Baker, Rodney C; Kramer, Robert E

    2013-07-01

    Cytochrome P450 (CYP)-mediated desulfuration of methyl parathion results in mechanism-based inhibition of the enzyme. Although previous data suggest that reactive sulfur is released and binds to the apoprotein, the identities of neither the adduct(s) nor the affected amino acid(s) have been clearly determined. In this study, nanospray tandem mass spectroscopy was used to analyze peptide digests of CYP resolved by SDS-PAGE from liver microsomes of male rats following incubation in the absence or presence of methyl parathion. Oxidative desulfuration was confirmed by measurement of methyl paraoxon, and inhibition of specific CYP isozymes was determined by measurement of testosterone hydroxylation. Total CYP content was quantified spectrophotometrically. Incubation of microsomes with methyl parathion decreased CYP content by 58%. This effect was not associated with a comparable increase in absorbance at 420 nm, suggesting the displacement of heme from the apoprotein. Rates of testosterone 2β- and 6β-hydroxylation, respectively, were reduced to 8 and 2%, implicating CYP3A and CYP2C11 in the oxidative desulfuration of methyl parathion. Mass spectrometric analysis identified 96 amu adducts to cysteines 64 and 378 of CYP3A1. In addition, a peptide containing cysteine 433 that coordinates with heme was possibly modified as it was detected in control, but not methyl parathion samples. A comparison of rat CYP3A1 with human CYP3A4 suggests that cysteines 64 and 378 reside along the substrate channel, remote from the active site. Alteration of these residues might modulate substrate entry to the binding pocket of the enzyme.

  15. Rapid Mass Spectrometric Analysis of a Novel Fucoidan, Extracted from the Brown Alga Coccophora langsdorfii

    PubMed Central

    Anastyuk, Stanislav D.; Imbs, Tatyana I.; Dmitrenok, Pavel S.; Zvyagintseva, Tatyana N.

    2014-01-01

    The novel highly sulfated (35%) fucoidan fraction Cf2 , which contained, along with fucose, galactose and traces of xylose and uronic acids was purified from the brown alga Coccophora langsdorfii. Its structural features were predominantly determined (in comparison with fragments of known structure) by a rapid mass spectrometric investigation of the low-molecular-weight fragments, obtained by “mild” (5 mg/mL) and “exhaustive” (maximal concentration) autohydrolysis. Tandem matrix-assisted laser desorption/ionization mass spectra (MALDI-TOF/TOFMS) of fucooligosaccharides with even degree of polymerization (DP), obtained by “mild” autohydrolysis, were the same as that observed for fucoidan from Fucus evanescens, which have a backbone of alternating (1 → 3)- and (1 → 4) linked sulfated at C-2 and sometimes at C-4 of 3-linked α-L-Fucp residues. Fragmentation patterns of oligosaccharides with odd DP indicated sulfation at C-2 and at C-4 of (1 → 3) linked α-L-Fucp residues on the reducing terminus. Minor sulfation at C-3 was also suggested. The “exhaustive” autohydrolysis allowed us to observe the “mixed” oligosaccharides, built up of fucose/xylose and fucose/galactose. Xylose residues were found to occupy both the reducing and nonreducing termini of FucXyl disaccharides. Nonreducing galactose residues as part of GalFuc disaccharides were found to be linked, possibly, by 2-type of linkage to fucose residues and were found to be sulfated, most likely, at position C-2. PMID:24578675

  16. Mass Spectrometric Detection of Neuropeptides Using Affinity-Enhanced Microdialysis with Antibody-Coated Magnetic Nanoparticles

    PubMed Central

    Schmerberg, Claire M.; Li, Lingjun

    2012-01-01

    Microdialysis (MD) is a useful sampling tool for many applications due to its ability to permit sampling from an animal concurrent with normal activity. MD is of particular importance in the field of neuroscience, in which it is used to sample neurotransmitters (NTs) while the animal is behaving in order to correlate dynamic changes in NTs with behavior. One important class of signaling molecules, the neuropeptides (NPs), however, presented significant challenges when studied with MD, due to the low relative recovery (RR) of NPs by this technique. Affinity-enhanced microdialysis (AE-MD) has previously been used to improve recovery of NPs and similar molecules. For AE-MD, an affinity agent (AA), such as an antibody-coated particle or free antibody, is added to the liquid perfusing the MD probe. This AA provides an additional mass transport driving force for analyte to pass through the dialysis membrane, and thus increases the RR. In this work, a variety of AAs have been investigated for AE-MD of NPs in vitro and in vivo, including particles with C18 surface functionality and antibody-coated particles. Antibody-coated magnetic nanoparticles (AbMnP) provided the best RR enhancement in vitro, with statistically significant (p<0.05) enhancements for 4 out of 6 NP standards tested, and RR increases up to 41-fold. These particles were then used for in vivo MD in the Jonah crab, Cancer borealis, during a feeding study, with mass spectrometric (MS) detection. 31 NPs were detected in a 30 min collection sample, compared to 17 when no AA was used. The use of AbMnP also increased the temporal resolution from 4–18 hrs in previous studies to just 30 min in this study. The levels of NPs detected were also sufficient for reliable quantitation with the MS system in use, permitting quantitative analysis of the concentration changes for 7 identified NPs on a 30 min time course during feeding. PMID:23249250

  17. Rapid characterization of lignocellulosic feedstocks for fuels and chemicals: Molecular beam mass spectrometric approach

    SciTech Connect

    Agblevor, F.A.; Davis, M.F.; Evans, R.J.

    1995-03-01

    Rapid characterization of biomass feedstocks has a pivotal role in the development of biomass energy because of the large number of samples that must be analyzed due to the diversity of biomass feedstocks and the significant differences in the chemical and physical properties of these feedstocks. Conventional chemical analysis of biomass feedstocks, although very useful, is time-consuming and not very practical for large scale screening experiments, hence the need for rapid characterization techniques. The molecular beam mass spectrometer and pyrolysis gas chromatography, which can analyze biomass pyrolysis vapors in real time, are unique tools for rapid qualitative and quantitative analyses of biomass feedstocks. Several biomass feedstocks (herbaceous, woody, and agricultural residues) were screened for the effects of storage, season of harvest, geographic location, clonal, and species variation on the pyrolysis products of the feedstocks. For herbaceous species such as sericea lespedeza, the season of harvest had a significant effect on the pyrolysis products. Effects of clonal variation on the composition of hybrid poplar feedstocks was easily discerned with the molecular beam mass spectrometric analysis. The effect of geographic location on the poplar clones pyrolysis products was minimal. However, in the case of switchgrass, varietal influence on the pyrolysis products was minimal, but where the plant was grown had a strong influence on the pyrolysis products of the feedstock. Significant differences because of species variation could also be shown from the pyrolysis products of various biomass feedstocks. The influence of storage time on biomass samples stored outside in the open could also be discerned from the pyrolysis products of the feedstocks. The differences noted in the pyrolysis products of the feedstocks were noted for samples which were significantly degraded during storage either through the action of microflora or weathering.

  18. Capillary liquid chromatography using laser-based and mass spectrometric detection. [Capillary zone electrophoresis (CZE); micellar electrokinetic capillary kchromatography (MECC)

    SciTech Connect

    Sepaniak, M.J.; Cook, K.D.

    1992-01-01

    In the years following the 1986 seminal paper (J. Chromatogr. Sci., 24, 347-352) describing modern capillary zone electrophoresis (CZE), the prominence of capillary electrokinetic separation techniques has grown. A related electrochromatographic technique is micellar electrokinetic capillary chromatography (MECC). This report presents a brief synopsis of research efforts during the current 3-year period. In addition to a description of analytical separations-based research, results of efforts to develop and expand spectrometric detection for the techniques is reviewed. Laser fluorometric detection schemes have been successfully advanced. Mass spectrometric research was less fruitful, largely owing to personnel limitations. A regenerable fiber optic sensor was developed that can be used to remotely monitor chemical carcinogens, etc. (DLC)

  19. High-Speed Tandem Mass Spectrometric in Situ Imaging by Nanospray Desorption Electrospray Ionization Mass Spectrometry

    SciTech Connect

    Lanekoff, Ingela T.; Burnum-Johnson, Kristin E.; Thomas, Mathew; Short, Joshua TL; Carson, James P.; Cha, Jeeyeon; Dey, Sudhansu K.; Yang, Pengxiang; Prieto Conaway, Maria C.; Laskin, Julia

    2013-10-15

    Nanospray desorption electrospray ionization (nano-DESI) combined with tandem mass spectrometry (MS/MS), high-resolution mass analysis (m/m=17,500 at m/z 200), and rapid spectral acquisition enabled simultaneous imaging and identification of more than 300 molecules from 92 selected m/z windows (± 1 Da) with a spatial resolution of better than 150 um. Uterine sections of implantation sites on day 6 of pregnancy were analyzed in the ambient environment without any sample pre-treatment. MS/MS imaging was performed by scanning the sample under the nano-DESI probe at 10 um/s while acquiring higher-energy collision-induced dissociation (HCD) spectra for a targeted inclusion list of 92 m/z values at a rate of ~6.3 spectra/s. Molecular ions and their corresponding fragments, separated using high-resolution mass analysis, were assigned based on accurate mass measurement. Using this approach, we were able to identify and image both abundant and low-abundance isobaric species within each m/z window. MS/MS analysis enabled efficient separation and identification of isobaric sodium and potassium adducts of phospholipids. Furthermore, we identified several metabolites associated with early pregnancy and obtained the first 2D images of these molecules.

  20. High-speed tandem mass spectrometric in situ imaging by nanospray desorption electrospray ionization mass spectrometry.

    PubMed

    Lanekoff, Ingela; Burnum-Johnson, Kristin; Thomas, Mathew; Short, Joshua; Carson, James P; Cha, Jeeyeon; Dey, Sudhansu K; Yang, Pengxiang; Prieto Conaway, Maria C; Laskin, Julia

    2013-10-15

    Nanospray desorption electrospray ionization (nano-DESI) combined with tandem mass spectrometry (MS/MS), high-resolution mass analysis of the fragment ions (m/Δm = 17 500 at m/z 200), and rapid spectral acquisition enabled simultaneous imaging and identification of a large number of metabolites and lipids from 92 selected m/z windows (±1 Da) with a spatial resolution of better than 150 μm. Mouse uterine sections of implantation sites on day 6 of pregnancy were analyzed in the ambient environment without any sample pretreatment. MS/MS imaging was performed by scanning the sample under the nano-DESI probe at 10 μm/s, while higher-energy collision-induced dissociation (HCD) spectra were acquired for a targeted inclusion list of 92 m/z values at a rate of ∼6.3 spectra/s. Molecular ions and their corresponding fragments, separated by high-resolution mass analysis, were assigned on the basis of accurate mass measurement. Using this approach, we were able to identify and image both abundant and low-abundance isobaric and isomeric species within each m/z window. MS/MS analysis enabled efficient separation and identification of isomeric and isobaric phospholipids that are difficult to separate in full-scan mode. Furthermore, we identified several metabolites associated with early pregnancy and obtained the first 2D images of these molecules.

  1. Mass Spectrometric Analysis of Soot Particles: Combining Bulk and Single Particle Instrumentation

    NASA Astrophysics Data System (ADS)

    Sierau, B.; Mensah, A. A.; Corbin, J. C.

    2011-12-01

    soot particles. The influence of the agglomerate structure of laboratory generated soot particles on the mass spectrometric analysis is investigated using particle conditioning procedures upstream of the SP-AMS that change the structure of the soot before the detection takes place. For this, a set-up consisting of a humidifier/thermodenuder system is applied to collapse and dry the initial particles. Preliminary studies show that soot particles coated with sulfuric acid are more susceptible to restructuring than those coated with adipic acid. This is attributed to the solid state of adipic acid at room temperature.

  2. Mass Spectrometric Identification of Isoforms of PR Proteins in Xylem Sap of Fungus-Infected Tomato1

    PubMed Central

    Rep, Martijn; Dekker, Henk L.; Vossen, Jack H.; de Boer, Albert D.; Houterman, Petra M.; Speijer, Dave; Back, Jaap W.; de Koster, Chris G.; Cornelissen, Ben J.C.

    2002-01-01

    The protein content of tomato (Lycopersicon esculentum) xylem sap was found to change dramatically upon infection with the vascular wilt fungus Fusarium oxysporum. Peptide mass fingerprinting and mass spectrometric sequencing were used to identify the most abundant proteins appearing during compatible or incompatible interactions. A new member of the PR-5 family was identified that accumulated early in both types of interaction. Other pathogenesis-related proteins appeared in compatible interactions only, concomitantly with disease development. This study demonstrates the feasibility of using proteomics for the identification of known and novel proteins in xylem sap, and provides insights into plant-pathogen interactions in vascular wilt diseases. PMID:12376655

  3. Partial least-squares-discriminant analysis differentiating Chinese wolfberries by UPLC-MS and flow injection mass spectrometric (FIMS) fingerprints.

    PubMed

    Lu, Weiying; Jiang, Qianqian; Shi, Haiming; Niu, Yuge; Gao, Boyan; Yu, Liangli Lucy

    2014-09-17

    Lycium barbarum L. fruits (Chinese wolfberries) were differentiated for their cultivation locations and the cultivars by ultraperformance liquid chromatography coupled with mass spectrometry (UPLC-MS) and flow injection mass spectrometric (FIMS) fingerprinting techniques combined with chemometrics analyses. The partial least-squares-discriminant analysis (PLS-DA) was applied to the data projection and supervised learning with validation. The samples formed clusters in the projected data. The prediction accuracies by PLS-DA with bootstrapped Latin partition validation were greater than 90% for all models. The chemical profiles of Chinese wolfberries were also obtained. The differentiation techniques might be utilized for Chinese wolfberry authentication.

  4. Gas chromatographic and mass spectrometric investigations of organic residues from Roman glass unguentaria.

    PubMed

    Ribechini, Erika; Modugno, Francesca; Colombini, Maria Perla; Evershed, Richard P

    2008-03-07

    A combination of gas chromatographic (GC) and mass spectrometric (MS) techniques, including direct exposure-MS (DE-MS), high-temperature GC-MS (HTGC-MS) and GC-MS of neutral and acid fractions, was employed to study the composition and recognise origin of the organic materials used to manufacture balm residues surviving in a series of glass unguentaria recovered from excavations of a Roman villa (Villa B) in the ancient town of Oplontis (Naples, Italy). DE-MS provided comprehensive 'fingerprint' information on the solvent soluble components of the contents of the unguentaria, while GC-MS analyses provided detailed molecular compositions, highlighting the presence of a wide range of compound classes including mid- and long-chain fatty acids, long-chain hydroxy-acids, n-alkanols, alkandiols, n-alkanes, long-chain monoesters, phytosterols and diterpenoid acids. Characteristic biomarkers and their distributions indicate the presence of beeswax, Pinaceae resin and another wax, as the main organic constituents of all of the preparations examined. In particular, the occurrence of phytosterols and long-chain monoesters, in which the acyl moiety was not exclusively palmitic acid, suggested the presence of a second waxy-lipid constituent of plant origin. The results are consistent with beeswax being used in the preparation of the cosmetics preserved in the unguentaria, while the other lipids are most likely the residue of some as yet unidentified plant extract(s), possibly deriving from the cuticular waxes of flowers and/or leaves. The composition of the extracts are consistent with the ancient practices of maceration and/or "enfleurage", in which lipid-based materials, such as beeswax, animal fat or vegetables oils, were used to extract aromatic and fragrant substances from resin, flowers, spices and scented wood, in order to produce unguents and balms.

  5. On-line monitoring of continuous beer fermentation process using automatic membrane inlet mass spectrometric system.

    PubMed

    Tarkiainen, Virpi; Kotiaho, Tapio; Mattila, Ismo; Virkajärvi, Ilkka; Aristidou, Aristos; Ketola, Raimo A

    2005-03-15

    A fully automatic membrane inlet mass spectrometric (MIMS) on-line instrumentation for the analysis of aroma compounds in continuous beer fermentation processes was constructed and tested. The instrumentation includes automatic filtration of the sample stream, flushing of all tubing between samples and pH control. The calibration standards can be measured periodically. The instrumentation has also an extra sample line that can be used for off-line sample collection or it can be connected to another on-line method. Detection limits for ethanol, acetic acid and eight organic beer aroma compounds were from mugl(-1) to low mgl(-1) levels and the standard deviations were less than 3.4%. The method has a good repeatability and linearity in the measurement range. Response times are shorter than or equal to 3min for all compounds except for ethyl caproate, which has a response time of 8min. In beer aroma compound analysis a good agreement between MIMS and static headspace gas chromatographic (HSGC) measurements was found. The effects of different matrix compounds commonly present in the fermentation media on the MIMS response to acetaldehyde, ethyl acetate and ethanol were studied. Addition of yeast did not have any effect on the MIMS response of ethanol or ethyl acetate. Sugars, glucose and xylose, increased the MIMS response of all studied analytes only slightly, whereas salts, ammonium chloride, ammonium nitrate and sodium chloride, increased the MIMS response of all three studied compounds prominently. The system was used for on-line monitoring of continuous beer fermentation with immobilised yeast. The results show that with MIMS it is possible to monitor the changes in the continuous process as well as delays in the two-phase process.

  6. Mass spectrometric quantification of salivary metanephrines – a pilot study in healthy controls

    PubMed Central

    Osinga, Thamara E; van der Horst-Schrivers, Anouk NA; van Faassen, Martijn; Kerstens, Michiel N; Dullaart, Robin PF; Pacak, Karel; Links, Thera P; Kema, Ido P

    2016-01-01

    Determination of metanephrine (MN), normetanephrine (NMN) and 3-methoxytyramine (3-MT) in saliva could be of diagnostic value in patients with pheochromocytoma. This preliminary study was set out to determine metanephrine concentrations in saliva from healthy subjects compared to their simultaneously measured plasma levels. In addition, we studied the possible influence of pre-analytical conditions such as a collection device, awakening, position, and eating on the salivary metanephrine levels. We included 11 healthy volunteers. Fasting blood and saliva samples were collected in seated position and after 30 minutes of horizontal rest. Saliva samples 30 minutes after eating were also collected. Saliva was collected with and without the use of a polyethylene salivette. Plasma and salivary MN, NMN and 3-MT concentrations were determined using a High-Performance Liquid Chromatography tandem mass spectrometric technique (LC-MS/MS) with automated solid phase extraction sample preparation. Metanephrines were detectable in saliva from all participants both in seated and the supine position. We found no significant correlation between the MN, NMN and 3-MT concentrations in saliva and plasma in the seated or supine position. In addition, there was no difference between MN, NMN and 3-MT concentrations collected with or without a collection device. Plasma MN, NMN, 3-MT and salivary NMN concentrations collected in seated position were significantly higher compared concentrations of samples collected in supine position (all P<.05). In conclusion, salivary metanephrines can be detected with LC-MS/MS with sufficient sensitivity and precision. Our findings warrant evaluation of salivary metanephrine measurement in the work-up of patients who are suspected to harbor pheochromocytoma. PMID:26874200

  7. Solid-state UV-MALDI mass spectrometric quantitation of fluroxypyr and triclopyr in soil.

    PubMed

    Ivanova, Bojidarka; Spiteller, Michael

    2015-06-01

    The work presented here refers firstly to solid-state UV-MALDI-Orbitrap-mass spectrometric analysis of fluroxypyr (A) and triclopyr (B) in soils under laboratory conditions. The experimental design has involved the following: (a) determination of analytes A and B in polycrystalline composites of organic materials 1-7, based on 2-piperidine (pyrrolidine or piperazine)-1-yl-ethyl ammonium salts in order to determine the effect of sample preparation techniques on method performance using commercial herbicide formulations and (b) analysis of non-(X j,k,l (i) ) and sterilized (Y j,k,l (i) ) soil samples (i-fold rate 1, 10, 100, or 1,000; j-pesticide type A or B; k-time (0, 5, 10, 20, and 50 days) and l = 1-3 replicated samples) having clay content ∈ 5.0-12.0 %, silt ∈ 23.0-51.1 %, sand ∈ 7.2-72.0 %, and pH ∈ 4.0-8.1. In order to obtain a high representativeness of the data toward real-field experiments, the pollution scheme has involved 1-, 10-, 100-, and 1,000-fold rates. The firstfold rate has concentration of pollutant A of 2.639 × 10(-4) g in 625 cm(2) soil horizon of 0-25 cm(2) (5 cm depth) according to registration report (PSM-Zulassungbericht) of German Federal Office of Consumer Protection and Food Safety (Bundesamt für Verbraucherschutz und Lebensmittelsicherheit) 6337/26.10.2009. The experimental design has involved quincunx systematic statistical approach for collection of soil samples. The performance has been compared with the corresponding statistical variable obtained, using an independent HPLC-ESI-(APCI-)-MS/MS analysis.

  8. Evaluation of serum phosphopeptides as potential cancer biomarkers by mass spectrometric absolute quantification.

    PubMed

    Zhai, Guijin; Wu, Xiaoyan; Luo, Qun; Wu, Kui; Zhao, Yao; Liu, Jianan; Xiong, Shaoxiang; Feng, Yu-Qi; Yang, Liping; Wang, Fuyi

    2014-07-01

    Mass spectrometric quantification of phosphopeptides is a challenge due to the ion suppression effect of highly abundant non-phosphorylated peptides in complex samples such as serum. Several strategies for relative quantification of serum phosphopeptides based on MS have been developed, but the power of relative quantities was limited when making direct comparisons between two groups of samples or acting as a clinical examination index. Herein, we describe an MS absolute quantification strategy combined with Titania Coated Magnetic Hollow Mesoporous Silica Microspheres (TiO2/MHMSM) enrichment and stable isotopic acetyl labeling for phosphopeptides in human serum. Four endogenous serum phosphopeptides generated by degradation of fibrinogen were identified by LC-ESI-MS/MS following TiO2/MHMSM enrichment. The ESI-MS signal intensity ratios of the four phosphopeptide standards labeled with N-acetoxy-H3-succinimide (H3-NAS) and N-acetoxy-D3-succinimide (D3-NAS), following TiO2/MHMSM capture are linearly correlated with the molar ratios of the "light" to "heavy" phosphopeptides over the range of 0.1-4 with an r(2) of up to 0.998 and a slope of close to 1. The recovery of the four phosphopeptides spiked at low, medium and high levels in human sera were 98.4-111.9% with RSDs ranging 2.0-10.1%. The absolute quantification of the phosphopeptides in serum samples of 20 healthy persons and 20 gastric cancer patients by the developed method demonstrated that 3 out of the 4 phosphopeptides showed remarkable variation in serum level between healthy and cancer groups, and the phosphopeptide DpSGEGDFLAEGGGVR is significantly down-regulated in the serum of patients, being a potential biomarker for gastric cancer diagnosis. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Mass spectrometric identification of formaldehyde-induced peptide modifications under in vivo protein cross-linking conditions.

    PubMed

    Toews, Judy; Rogalski, Jason C; Clark, Thomas J; Kast, Juergen

    2008-06-23

    Formaldehyde cross-linking of proteins is emerging as a novel approach to study protein-protein interactions in living cells. It has been shown to be compatible with standard techniques used in functional proteomics such as affinity-based protein enrichment, enzymatic digestion, and mass spectrometric protein identification. So far, the lack of knowledge on formaldehyde-induced protein modifications and suitable mass spectrometric methods for their targeted detection has impeded the identification of the different types of cross-linked peptides in these samples. In particular, it has remained unclear whether in vitro studies that identified a multitude of amino acid residues reacting with formaldehyde over the course of several days are suitable substitutes for the much shorter reaction times of 10-20 min used in cross-linking experiments in living cells. The current study on model peptides identifies amino-termini as well as lysine, tryptophan, and cysteine side chains, i.e. a small subset of those modified after several days, as the major reactive sites under such conditions, and suggests relative position in the peptide sequence as well as sequence microenvironment to be important factors that govern reactivity. Using MALDI-MS, mass increases of 12 Da on amino groups and 30 Da on cysteines were detected as the major reaction products, while peptide fragment ion analysis by tandem mass spectrometry was used to localize the actual modification sites on a peptide. Non-specific cross-linking was absent, and could only be detected with low yield at elevated peptide concentrations. The detailed knowledge on the constraints and products of the formaldehyde reaction with peptides after short incubation times presented in this study is expected to facilitate the targeted mass spectrometric analysis of proteins after in vivo formaldehyde cross-linking.

  10. Lipopeptides from the Banyan Endophyte, Bacillus subtilis K1: Mass Spectrometric Characterization of a Library of Fengycins

    NASA Astrophysics Data System (ADS)

    Pathak, Khyati V.; Keharia, Haresh; Gupta, Kallol; Thakur, Suman S.; Balaram, Padmanabhan

    2012-10-01

    Mass spectrometric analysis of a banyan endophyte, Bacillus subtilis K1, extract showing broad spectrum antifungal activity revealed a complex mixture of lipopeptides, iturins, surfactins, and fengycins. Fractionation by reversed-phase high performance liquid chromatography (HPLC) facilitated a detailed analysis of fengycin microheterogeneity. Matrix assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) mass spectrometric studies permitted the identification of several new fengycin variants. Four major sites of heterogeneity are identified: (1) N-terminus β-hydroxy fatty acid moiety, where chain length variation and the presence of unsaturation occur, (2) position 6 (Ala/Val/Ile/Leu), (3) position 10 (Val/Ile) within the macrocyclic ring, and (4) Gln to Glu replacement at position 8, resulting in fengycin variants that differ in mass by 1 Da. Diagnostic fragment ions provide a quick method for localizing the sites of variation in the macrocycle or the linear segment. Subsequent establishment of the sequences is achieved by MS/MS analysis of linear fengycin species produced by hydrolysis of the macrocyclic lactone. Unsaturation in the fatty acid chain and the presence of linear precursors in the B. subtilis K1 extract are also established by mass spectrometry. The anomalous distribution of intensities within isotopic multiplets is a diagnostic for Gln/Glu replacements. High resolution mass spectrometry facilitates the identification of fengycin species differing by 1 Da by localizing the variable position (Gln8/Glu8) in the fengycin variants.

  11. Mass spectrometry based lipid(ome) analyzer and molecular platform: a new software to interpret and analyze electrospray and/or matrix-assisted laser desorption/ionization mass spectrometric data of lipids: a case study from Mycobacterium tuberculosis.

    PubMed

    Sabareesh, Varatharajan; Singh, Gurpreet

    2013-04-01

    Mass Spectrometry based Lipid(ome) Analyzer and Molecular Platform (MS-LAMP) is a new software capable of aiding in interpreting electrospray ionization (ESI) and/or matrix-assisted laser desorption/ionization (MALDI) mass spectrometric data of lipids. The graphical user interface (GUI) of this standalone programme is built using Perl::Tk. Two databases have been developed and constituted within MS-LAMP, on the basis of Mycobacterium tuberculosis (M. tb) lipid database (www.mrl.colostate.edu) and that of Lipid Metabolites and Pathways Strategy Consortium (LIPID MAPS; www.lipidmaps.org). Different types of queries entered through GUI would interrogate with a chosen database. The queries can be molecular mass(es) or mass-to-charge (m/z) value(s) and molecular formula. LIPID MAPS identifier also can be used to search but not for M. tb lipids. Multiple choices have been provided to select diverse ion types and lipids. Satisfying to input parameters, a glimpse of various lipid categories and their population distribution can be viewed in the output. Additionally, molecular structures of lipids in the output can be seen using ChemSketch (www.acdlabs.com), which has been linked to the programme. Furthermore, a version of MS-LAMP for use in Linux operating system is separately available, wherein PyMOL can be used to view molecular structures that result as output from General Lipidome MS-LAMP. The utility of this software is demonstrated using ESI mass spectrometric data of lipid extracts of M. tb grown under two different pH (5.5 and 7.0) conditions. Copyright © 2013 John Wiley & Sons, Ltd.

  12. Biochemical Individuality Reflected in Chromatographic, Electrophoretic and Mass-Spectrometric Profiles

    PubMed Central

    Novotny, Milos V.; Soini, Helena A.; Mechref, Yehia

    2008-01-01

    This review discusses the current trends in molecular profiling for the emerging systems biology applications. Historically, the methodological developments in separation science were coincident with the availability of new ionization techniques in mass spectrometry. Coupling miniaturized separation techniques with technologically-advanced MS instrumentation and the modern data processing capabilities are at the heart of current platforms for proteomics, glycomics and metabolomics. These are being featured here by the examples from quantitative proteomics, glycan mapping and metabolomic profiling of physiological fluids. PMID:18551752

  13. Mass Spectrometric Assay and Physiological-Pharmacological Activity of Androgenic Neurosteroids

    PubMed Central

    Reddy, Doodipala S.

    2008-01-01

    Steroid hormones play a key role in the pathophysiology of several brain disorders. Testosterone modulates neuronal excitability, but the underlying mechanisms are obscure. There is emerging evidence that testosterone-derived “androgenic neurosteroids”, 3α-androstanediol and 17β-estradiol, mediate the testosterone effects on neural excitability and seizure susceptibility. Testosterone undergoes metabolism to neurosteroids via two distinct pathways. Aromatization of the A-ring converts testosterone into 17β-estradiol. Reduction of testosterone by 5α-reductase generates 5α-dihydrotestosterone, which is then converted to 3α-androstanediol, a powerful GABAA receptor-modulating neurosteroid with anticonvulsant properties. Although the 3α-androstanediol is an emerging neurosteroid in the brain, there is no specific and sensitive assay for determination of 3α-androstanediol in biological samples. This article describes the development and validation of mass spectrometric assay of 3α-androstanediol, and the molecular mechanisms underlying the testosterone modulation of seizure susceptibility. A liquid chromatography-tandem mass spectrometry assay to measure 3α-androstanediol is validated with excellent linearity, specificity, sensitivity, and reproducibility. Testosterone modulation of seizure susceptibility is demonstrated to occur through its conversion to neurosteroids with “anticonvulsant” and “proconvulsant” actions and hence the net effect of testosterone on neural excitability and seizure activity depends on the levels of distinct testosterone metabolites. The proconvulsant effect of testosterone is associated with increases in plasma 17β-estradiol concentrations. The 5α-reduced metabolites of testosterone, 5α-dihydrotestosterone and 3α-androstanediol, had powerful anticonvulsant activity. Overall, the testosterone-derived neurosteroids 3α-androstanediol and 17β-estradiol could contribute to the net cellular actions of testosterone in the

  14. Desorption Electrospray Ionization (DESI) Mass Spectrometric Imaging of the Distribution of Rohitukine in the Seedling of Dysoxylum binectariferum Hook. F

    PubMed Central

    Mohana Kumara, Patel; Srimany, Amitava; Arunan, Suganya; Ravikanth, Gudasalamani; Uma Shaanker, Ramanan; Pradeep, Thalappil

    2016-01-01

    Ambient ionization mass spectrometric imaging of all parts of the seedling of Dysoxylum binectariferum Hook. f (Meliaceae) was performed to reconstruct the molecular distribution of rohitukine (Rh) and related compounds. The species accumulates Rh, a prominent chromone alkaloid, in its seeds, fruits, and stem bark. Rh possesses anti-inflammatory, anti-cancer, and immuno-modulatory properties. Desorption electrospray ionization mass spectrometry imaging (DESI MSI) and electrospray ionization (ESI) tandem mass spectrometry (MS/MS) analysis detected Rh as well as its glycosylated, acetylated, oxidized, and methoxylated analogues. Rh was predominantly distributed in the main roots, collar region of the stem, and young leaves. In the stem and roots, Rh was primarily restricted to the cortex region. The identities of the metabolites were assigned based on both the fragmentation patterns and exact mass analyses. We discuss these results, with specific reference to the possible pathways of Rh biosynthesis and translocation during seedling development in D. binectariferum. PMID:27362422

  15. Desorption Electrospray Ionization (DESI) Mass Spectrometric Imaging of the Distribution of Rohitukine in the Seedling of Dysoxylum binectariferum Hook. F.

    PubMed

    Mohana Kumara, Patel; Srimany, Amitava; Arunan, Suganya; Ravikanth, Gudasalamani; Uma Shaanker, Ramanan; Pradeep, Thalappil

    2016-01-01

    Ambient ionization mass spectrometric imaging of all parts of the seedling of Dysoxylum binectariferum Hook. f (Meliaceae) was performed to reconstruct the molecular distribution of rohitukine (Rh) and related compounds. The species accumulates Rh, a prominent chromone alkaloid, in its seeds, fruits, and stem bark. Rh possesses anti-inflammatory, anti-cancer, and immuno-modulatory properties. Desorption electrospray ionization mass spectrometry imaging (DESI MSI) and electrospray ionization (ESI) tandem mass spectrometry (MS/MS) analysis detected Rh as well as its glycosylated, acetylated, oxidized, and methoxylated analogues. Rh was predominantly distributed in the main roots, collar region of the stem, and young leaves. In the stem and roots, Rh was primarily restricted to the cortex region. The identities of the metabolites were assigned based on both the fragmentation patterns and exact mass analyses. We discuss these results, with specific reference to the possible pathways of Rh biosynthesis and translocation during seedling development in D. binectariferum.

  16. Gas chromatographic/mass spectrometric analyses of unknown analytical response in imported Fava beans: 4-chloro-6-methoxyindole.

    PubMed

    Petzinger, G; Barry, T L; Roach, J A; Musser, S M; Sphon, J

    1995-01-01

    A halogenated unidentified analytical response (UAR) was encountered in a number of imported Fava bean samples during the Food and Drug Administration's routine pesticide-monitoring program. Gas chromatographic/mass spectrometric (GC/MS) analyses identified the halogenated component as 4-chloro-6-methoxyindole, a naturally occurring promutagen in Fava beans that has been linked to incidents of gastric cancer. Data from electron impact, positive and negative chemical ionization, collision-induced dissociation, and deuteration studies of this compound are presented, along with GC retention time data.

  17. Gas chromatographic-mass spectrometric determination of macrolide antibiotics in beef and pork using single ion monitoring.

    PubMed

    Takatsuki, K; Ushizawa, I; Shoji, T

    1987-03-27

    A gas chromatographic-mass spectrometric (GC-MS) method using single ion monitoring (SIM) is described for the determination of residual macrolide antibiotics, oleandomycin, kitasamycin, spiramycin and tylosin, in beef and pork. For GC-MS determination, oleandomycin is acid hydrolysed to desoleandomycin and acetylated, in the same way as erythromycin. However, for elution from a GC column, the carbon-carbon double bonds in the antibiotics must be hydrogenated to single bonds before acid hydrolysis. Kitasamycin and spiramycin are therefore converted into hydroforocidine acetate and tylosin into hydro-O-mycaminosyl tylonolide acetate, which are determined by GC-MS with SIM.

  18. Mass spectrometric fragmentation pathways of isotope labeled 2,5-disubstituted-1,3,4-oxadiazoles and thiadiazoles

    NASA Astrophysics Data System (ADS)

    Franski, Rafal; Gierczyk, Blazej; Schroeder, Grzegorz

    2004-01-01

    The mass spectrometric decomposition of protonated, lithiated and methylated (quaternary derivatives) 2-(4'-methoxy)phenyl-5-phenyl-1,3,4-oxadiazoles, containing 13C atom at 5 position of oxadiazole ring as well as its thia correspondent is discussed. The electron-donor properties of C-4' substituent favor cationization of N(3) atom and as a consequence, the losses of HNC(2)O, LiNC(2)O, CH3NC(2)O molecules are favored over HNC(5)O, LiNC(5)O, CH3NC(5)O molecules. Analogous results have been obtained for HNCS and CH3NCS elimination from thiadiazole.

  19. Asymmetric Morita-Baylis-Hillman Reaction: Catalyst Development and Mechanistic Insights Based on Mass Spectrometric Back-Reaction Screening.

    PubMed

    Isenegger, Patrick G; Bächle, Florian; Pfaltz, Andreas

    2016-12-05

    An efficient protocol for the evaluation of catalysts for the asymmetric Morita-Baylis-Hillman (MBH) reaction was developed. By mass spectrometric back-reaction screening of quasi-enantiomeric MBH products, an efficient bifunctional phosphine catalyst was identified that outperforms literature-known catalysts in the MBH reaction of methyl acrylate with aldehydes. The close match between the selectivities measured for the forward and back reaction and kinetic measurements provided strong evidence that the aldol step and not the subsequent proton transfer is rate- and enantioselectivity-determining.

  20. Design and performance of a mass spectrometric facility for measuring helium isotopes in natural waters and for low-level tritium determination by the 3He ingrowth method.

    PubMed

    Jean-Baptiste, P; Mantisi, F; Dapoigny, A; Stievenard, M

    1992-07-01

    The design and performance of a mass spectrometric system for the measurement of helium isotopes and very low tritium concentrations in natural waters are described and discussed in the light of analytical precision and accuracy. The system consists of a VG 3000 mass spectrometer with a fully automated inlet system for preparation and purification of the samples. Along with this mass spectrometric system, different custom-fabricated units are described, especially designed for taking samples, extracting helium or degassing tritium samples prior to the mass spectrometric analysis. The 3He detection limit of the system is close to 10(-16) cm3 STP corresponding to a tritium level of 0.003 TU for a 500 g water sample stored six months for 3He regrowth. A vertical oceanic tritium profile from the south hemisphere is presented as an illustration of the system's capability to detect very low tritium concentrations in the environment.

  1. Determination of beta-2 microglobulin levels in plasma using a high-throughput mass spectrometric immunoassay system.

    PubMed

    Niederkofler, E E; Tubbs, K A; Gruber, K; Nedelkov, D; Kiernan, U A; Williams, P; Nelson, R W

    2001-07-15

    A high-throughput mass spectrometric immunoassay (MSIA) system for the analysis of proteins directly from biological fluids is reported. A 96-well-format robotic workstation equipped with antibody-derivatized affinity pipet tips was used for the parallel extraction of specific proteins from samples and subsequent deposition onto 96-well arrayed matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) targets. Interferences from nonspecifically bound proteins were minimized through choice of appropriate affinity pipet tip derivatization chemistries. Sample preparation for MALDI-TOFMS was enhanced through the use of hydrophobic/hydrophilic contrasting targets, which also presented functionalities found to promote matrix/analyte crystal growth. Automated mass spectrometry was used in the unattended acquisition of data, resulting in an analysis rate of approximately 100 samples/h (biological fluid-->data). The quantitative MSIA of beta2m levels present in human plasma samples is given as illustration.

  2. Mass spectrometric characterization of toremifene metabolites in human urine by liquid chromatography-tandem mass spectrometry with different scan modes.

    PubMed

    Lu, Jianghai; Wang, Xiaobing; Xu, Youxuan; Dong, Ying; Yang, Shuming; Wu, Yun; Qin, Yang; Wu, Moutian

    2011-02-07

    The metabolism and excretion of toremifene were investigated in one healthy male volunteer after a single oral administration of 120 mg toremifene citrate. Different liquid chromatographic/tandem mass spectrometric (LC/MS/MS) scanning techniques were carried out for the characterization of the metabolites in human urine for doping control purposes. The potential characteristic fragmentation pathways of toremifene and its major metabolites were presented. An approach for the metabolism study of toremifene and its analogs by liquid chromatography-tandem mass spectrometry was established. Five different LC/MS/MS scanning methods based on precursor ion scan (precursor ion scan of m/z 72.2, 58.2, 44.2, 45.2, 88.2 relative to five metabolic pathways) in positive ion mode were assessed to recognize the metabolites. Based on product ion scan and precursor ion scan techniques, the metabolites were proposed to be identified as 4-hydroxy-toremifene (m/z 422.4), 4'-hydroxy-toremifene (m/z 422.4), α-hydroxy-toremifene (m/z 422.4), 3,4-dihydroxy-toremifene (m/z 404.2), toremifene acid (m/z 402.2), 3-hydroxy-4-methoxy-toremifene (m/z 456.2), dihydroxy-dehydro-toremifene (m/z 440.2), 3,4-dihydroxy-toremifene (m/z 438.2), N-demethyl-4-hydroxy-toremifene (m/z 408.3), N-demethyl-3-hydroxy-4-methoxy-toremifene (m/z 438.3). In addition, a new metabolite with a protonated molecule at m/z 390.3 was detected in all urine samples. The compound was identified by LC/MS/MS as N-demethyl-4,4'-dihydroxy-tamoxifene. The results indicated that 3,4-dihydroxy-toremifene (m/z 404.2), toremifene acid (m/z 402.2) and N-demethyl-4,4'-dihydroxy-tamoxifene (m/z 390.3) were major metabolites in human urine.

  3. Investigation of the mouse cerebellum using STIM and μ-PIXE spectrometric and FTIR spectroscopic mapping and imaging

    NASA Astrophysics Data System (ADS)

    Hackett, M. J.; Siegele, R.; El-Assaad, F.; McQuillan, J. A.; Aitken, J. B.; Carter, E. A.; Grau, G. E.; Hunt, N. H.; Cohen, D.; Lay, P. A.

    2011-10-01

    The cerebral biochemistry associated with the development of many neurological diseases remains poorly understood. In particular, incomplete understanding of the mechanisms through which vascular inflammation manifests in tissue damage and altered brain function is a significant hindrance to the development of improved patient therapies. To this extent, a combination of spectrometric/spectroscopic mapping/imaging methods with an inherent ability to provide a wealth of biochemical and physical information have been investigated to understand further the pathogenesis of brain disease. In this study, proton-induced X-ray emission (PIXE) mapping was combined with scanning transmission ion microscopy (STIM) mapping and Fourier-transform infrared (FTIR) imaging of the same tissue sample to study directly the composition of the murine (mouse) cerebellum. The combination of the elemental, density and molecular information provided by these techniques enabled differentiation between four specific tissue types within the murine cerebellum (grey matter, white matter, molecular layer and micro blood vessels). The results presented are complementary, multi-technique measurements of the same tissue sample. They show elemental, density and molecular differences among the different tissue types.

  4. High Throughput In Situ DDA Analysis of Neuropeptides by Coupling Novel Multiplex Mass Spectrometric Imaging (MSI) with Gas-Phase Fractionation

    NASA Astrophysics Data System (ADS)

    OuYang, Chuanzi; Chen, Bingming; Li, Lingjun

    2015-12-01

    Matrix-assisted laser desorption/ionization (MALDI) mass spectrometric imaging (MSI) is a powerful tool to map the spatial distribution of biomolecules on tissue sections. Recent developments of hybrid MS instruments allow combination of different types of data acquisition by various mass analyzers into a single MSI analysis, which reduces experimental time and sample consumptions. Here, using the well-characterized crustacean nervous system as a test-bed, we explore the utility of high resolution and accurate mass (HRAM) MALDI Orbitrap platform for enhanced in situ characterization of the neuropeptidome with improved chemical information. Specifically, we report on a multiplex-MSI method, which combines HRAM MSI with data dependent acquisition (DDA) tandem MS analysis in a single experiment. This method enables simultaneous mapping of neuropeptide distribution, sequence validation, and novel neuropeptide discovery in crustacean neuronal tissues. To enhance the dynamic range and efficiency of in situ DDA, we introduced a novel approach of fractionating full m/z range into several sub-mass ranges and embedding the setup using the multiplex-DDA-MSI scan events to generate pseudo fractionation before MS/MS scans. The division of entire m/z into multiple segments of m/z sub-ranges for MS interrogation greatly decreased the complexity of molecular species from tissue samples and the heterogeneity of the distribution and variation of intensities of m/z peaks. By carefully optimizing the experimental conditions such as the dynamic exclusion, the multiplex-DDA-MSI approach demonstrates better performance with broader precursor coverage, less biased MS/MS scans towards high abundance molecules, and improved quality of tandem mass spectra for low intensity molecular species.

  5. High Throughput In Situ DDA Analysis of Neuropeptides by Coupling Novel Multiplex Mass Spectrometric Imaging (MSI) with Gas-Phase Fractionation.

    PubMed

    OuYang, Chuanzi; Chen, Bingming; Li, Lingjun

    2015-12-01

    Matrix-assisted laser desorption/ionization (MALDI) mass spectrometric imaging (MSI) is a powerful tool to map the spatial distribution of biomolecules on tissue sections. Recent developments of hybrid MS instruments allow combination of different types of data acquisition by various mass analyzers into a single MSI analysis, which reduces experimental time and sample consumptions. Here, using the well-characterized crustacean nervous system as a test-bed, we explore the utility of high resolution and accurate mass (HRAM) MALDI Orbitrap platform for enhanced in situ characterization of the neuropeptidome with improved chemical information. Specifically, we report on a multiplex-MSI method, which combines HRAM MSI with data dependent acquisition (DDA) tandem MS analysis in a single experiment. This method enables simultaneous mapping of neuropeptide distribution, sequence validation, and novel neuropeptide discovery in crustacean neuronal tissues. To enhance the dynamic range and efficiency of in situ DDA, we introduced a novel approach of fractionating full m/z range into several sub-mass ranges and embedding the setup using the multiplex-DDA-MSI scan events to generate pseudo fractionation before MS/MS scans. The division of entire m/z into multiple segments of m/z sub-ranges for MS interrogation greatly decreased the complexity of molecular species from tissue samples and the heterogeneity of the distribution and variation of intensities of m/z peaks. By carefully optimizing the experimental conditions such as the dynamic exclusion, the multiplex-DDA-MSI approach demonstrates better performance with broader precursor coverage, less biased MS/MS scans towards high abundance molecules, and improved quality of tandem mass spectra for low intensity molecular species. Graphical Abstract ᅟ.

  6. The Mechanism of 2-Furaldehyde Formation from d-Xylose Dehydration in the Gas Phase. A Tandem Mass Spectrometric Study

    NASA Astrophysics Data System (ADS)

    Ricci, Andreina; Piccolella, Simona; Pepi, Federico; Garzoli, Stefania; Giacomello, Pierluigi

    2013-07-01

    The mechanism of reactions occurring in solution can be investigated also in the gas phase by suited mass spectrometric techniques, which allow to highlight fundamental mechanistic features independent of the influence of the medium and to clarifying controversial hypotheses proposed in solution studies. In this work, we report a gas-phase study performed by electrospray triple stage quadrupole mass spectrometry (ESI-TSQ/MS) on the dehydration of d-xylose, leading mainly to the formation of 2-furaldehyde (2-FA). It is generally known in carbohydrate chemistry that the thermal acid catalyzed dehydration of pentoses leads to the formation of 2-FA, but several aspects on the solution-phase mechanism are controversial. Here, gaseous reactant ions corresponding to protonated xylose molecules obtained from ESI of a solution containing d-xylose and ammonium acetate as protonating reagent were allowed to undergo collisionally activated decomposition (CAD) into the triple stage quadrupole analyzer. The product ion mass spectra of protonated xylose are characterized by the presence of ionic intermediates arising from xylose dehydration, which were structurally characterized by their fragmentation patterns. As expected, the xylose triple dehydration leads to the formation of the ion at m/z 97, corresponding to protonated 2-FA. On the basis of mass spectrometric evidences, we demonstrated that in the gas phase, the formation of 2-FA involves protonation at the OH group bound to the C1 atom of the sugar, the first ionic intermediate being characterized by a cyclic structure. Finally, energy resolved product ion mass spectra allowed to obtain information on the energetic features of the d-xylose→2-FA conversion.

  7. Evaluation of mass spectrometric data using principal component analysis for determination of the effects of organic lakes on protein binder identification.

    PubMed

    Hrdlickova Kuckova, Stepanka; Rambouskova, Gabriela; Hynek, Radovan; Cejnar, Pavel; Oltrogge, Doris; Fuchs, Robert

    2015-11-01

    Matrix-assisted laser desorption/ionisation-time of flight (MALDI-TOF) mass spectrometry is commonly used for the identification of proteinaceous binders and their mixtures in artworks. The determination of protein binders is based on a comparison between the m/z values of tryptic peptides in the unknown sample and a reference one (egg, casein, animal glues etc.), but this method has greater potential to study changes due to ageing and the influence of organic/inorganic components on protein identification. However, it is necessary to then carry out statistical evaluation on the obtained data. Before now, it has been complicated to routinely convert the mass spectrometric data into a statistical programme, to extract and match the appropriate peaks. Only several 'homemade' computer programmes without user-friendly interfaces are available for these purposes. In this paper, we would like to present our completely new, publically available, non-commercial software, ms-alone and multiMS-toolbox, for principal component analyses of MALDI-TOF MS data for R software, and their application to the study of the influence of heterogeneous matrices (organic lakes) for protein identification. Using this new software, we determined the main factors that influence the protein analyses of artificially aged model mixtures of organic lakes and fish glue, prepared according to historical recipes that were used for book illumination, using MALDI-TOF peptide mass mapping. Copyright © 2015 John Wiley & Sons, Ltd.

  8. In Situ Probing of Cholesterol in Astrocytes at the Single Cell Level using Laser Desorption Ionization Mass Spectrometric Imaging with Colloidal Silver

    SciTech Connect

    Perdian, D.C.; Cha, Sangwon; Oh, Jisun; Sakaguchi, Donald S.; Yeung, Edward S.; and Lee, Young Jin

    2010-03-18

    Mass spectrometric imaging has been utilized to localize individual astrocytes and to obtain cholesterol populations at the single-cell level in laser desorption ionization (LDI) with colloidal silver. The silver ion adduct of membrane-bound cholesterol was monitored to detect individual cells. Good correlation between mass spectrometric and optical images at different cell densities indicates the ability to perform single-cell studies of cholesterol abundance. The feasibility of quantification is confirmed by the agreement between the LDI-MS ion signals and the results from a traditional enzymatic fluorometric assay. We propose that this approach could be an effective tool to study chemical populations at the cellular level.

  9. In situ probing of cholesterol in astrocytes at the single-cell level using laser desorption ionization mass spectrometric imaging with colloidal silver.

    PubMed

    Perdian, D C; Cha, Sangwon; Oh, Jisun; Sakaguchi, Donald S; Yeung, Edward S; Lee, Young Jin

    2010-04-30

    Mass spectrometric imaging has been utilized to localize individual astrocytes and to obtain cholesterol populations at the single-cell level in laser desorption ionization (LDI) with colloidal silver. The silver ion adduct of membrane-bound cholesterol was monitored to detect individual cells. Good correlation between mass spectrometric and optical images at different cell densities indicates the ability to perform single-cell studies of cholesterol abundance. The feasibility of quantification is confirmed by the agreement between the LDI-MS ion signals and the results from a traditional enzymatic fluorometric assay. We propose that this approach could be an effective tool to study chemical populations at the cellular level.

  10. Pyridine N-oxide and pyridine-d5 N-oxide: an electrospray/tandem mass spectrometric study carried out at high mass resolution.

    PubMed

    March, Raymond E; Stadey, Christopher J; Lewars, Errol G

    2005-01-01

    A mass spectrometric study of pyridine N-oxide and pyridine-d5 N-oxide was carried out with a hybrid quadrupole/time-of-flight (TOF) mass spectrometer coupled with an electrospray (ES) source. In addition to the observation of protonated, sodiated, and proton-bound dimers of pyridine N-oxide and pyridine-d5 N-oxide, mass scans revealed the presence of several doubly-charged ion species. Doubly-charged ions of m/z 191 were identified as diprotonated tetramers of pyridine N-oxide; a structure has been proposed for the diprotonated tetramer and its energy relative to that of protonated pyridine N-oxide has been obtained from geometry optimizations. The principal ion species observed were subjected to collision-induced dissociation; accurate mass measurements were made of each fragment ion so as to determine its elemental composition. On the basis of mass spectrometric evidence, it is suggested that dissociation of pyridine N-oxide may occur during the ES process and the resulting fragments become embedded in doubly-charged ions. The proton affinity for both pyridine N-oxide and pyridine-d5 N-oxide was calculated; the difference between these proton affinities was compared with an experimentally determined difference between the proton affinities of pyridine N-oxide and pyridine-d5 N-oxide.

  11. Matrix-assisted laser desorption/ionization mass spectrometric analysis of uncomplexed highly sulfated oligosaccharides using ionic liquid matrices.

    PubMed

    Laremore, Tatiana N; Murugesan, Saravanababu; Park, Tae-Joon; Avci, Fikri Y; Zagorevski, Dmitri V; Linhardt, Robert J

    2006-03-15

    Direct UV matrix-assisted laser desorption/ionization (MALDI) mass spectrometric analysis of uncomplexed, underivatized, highly sulfated oligosaccharides has been carried out using ionic liquids as matrices. Under conventionally used MALDI time-of-flight experimental conditions, uncomplexed polysulfated oligosaccharides do not produce any signal. We report that 1-methylimidazolium alpha-cyano-4-hydroxycinnamate and butylammonium 2,5-dihydroxybenzoate ionic liquid matrices allow the detection of picomole amounts of the sodium salts of a disaccharide, sucrose octasulfate, and an octasulfated pentasaccharide, Arixtra. The experimental results indicate that both analytes undergo some degree of thermal fragmentation with a mass loss corresponding to cleavage of O-SO3Na bonds in the matrix upon laser irradiation, reflecting lability of sulfo groups.

  12. Matrix-Assisted Laser Desorption/Ionization Mass Spectrometric Analysis of Uncomplexed Highly Sulfated Oligosaccharides Using Ionic Liquid Matrices

    PubMed Central

    Laremore, Tatiana N.; Murugesan, Saravanababu; Park, Tae-Joon; Avci, Fikri Y.; Zagorevski, Dmitri V.; Linhardt, Robert J.

    2014-01-01

    Direct UV matrix-assisted laser desorption/ionization (MALDI) mass spectrometric analysis of uncomplexed, underivatized, highly sulfated oligosaccharides has been carried out using ionic liquids as matrices. Under conventionally used MALDI time-of-flight experimental conditions, uncomplexed polysulfated oligosaccharides do not produce any signal. We report that 1-methylimidazolium α-cyano-4-hydroxycinnamate and butylammonium 2,5-dihydroxybenzoate ionic liquid matrices allow the detection of picomole amounts of the sodium salts of a disaccharide, sucrose octasulfate, and an octasulfated pentasaccharide, Arixtra. The experimental results indicate that both analytes undergo some degree of thermal fragmentation with a mass loss corresponding to cleavage of O–SO3Na bonds in the matrix upon laser irradiation, reflecting lability of sulfo groups. PMID:16536411

  13. Vitamin D-metabolites from human plasma and mass spectrometric analysis by fast heavy ion induced desorption

    NASA Astrophysics Data System (ADS)

    Fohlman, J.; Peterson, P. A.; Kamensky, I.; Håkansson, P.; Sundqvist, B.

    1982-07-01

    D-vitamin metabolites have been isolated from human serum employing chromatographic techniques. The serum carrier protein for vitamin D (DBP) was first isolated by immunosorbent chromatography. Lipid ligands associated with DBP were then extracted with hexane and separated by high pressure liquid chromatography (HPLC). Detection of vitamin D metabolites by their absorbance of ultraviolet light is not sufficiently sensitive to monitor all vitamin D derivatives from a few millilitres of serum. Therefore, further analyses are necessary to quantitate these compounds. We have begun to develop a mass spectrometric method to achieve a reliable, quantitative procedure. As a first step towards this goal a number of pure samples of vitamin D compounds have been studied in a time-of-flight mass spectrometer based on fast heavy ion induced desorption. All vitamin D compounds examined could be detected and identified by their molecular ion and fragment spectra.

  14. Ultraviolet irradiation-induced substitution of fluorine with hydroxyl radical for mass spectrometric analysis of perfluorooctane sulfonyl fluoride.

    PubMed

    Wang, Peng; Tang, Xuemei; Huang, Lulu; Kang, Jie; Zhong, Hongying

    2016-01-28

    A rapid and solvent free substitution reaction of a fluorine atom in perfluorooctane sulfonyl fluoride (PFOSF) with a hydroxyl radical is reported. Under irradiation of ultraviolet laser on semiconductor nanoparticles or metal surfaces, hydroxyl radicals can be generated through hole oxidization. Among all fluorine atoms of PFOSF, highly active hydroxyl radicals specifically substitute the fluorine of sulfonyl fluoride functional group. Resultant perfluorooctane sulfonic acid is further ionized through capture of photo-generated electrons that switch the neutral molecules to negatively charged odd electron hypervalent ions. The unpaired electron subsequently initiates α O-H bond cleavage and produces perfluorooctane sulfonate negative ions. Hydroxyl radical substitution and molecular dissociation of PFOSF have been confirmed by masses with high accuracy and resolution. It has been applied to direct mass spectrometric imaging of PFOSF adsorbed on surfaces of plant leaves. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Direct tandem mass spectrometric analysis of amino acids in plasma using fluorous derivatization and monolithic solid-phase purification.

    PubMed

    Tamashima, Erina; Hayama, Tadashi; Yoshida, Hideyuki; Imakyure, Osamu; Yamaguchi, Masatoshi; Nohta, Hitoshi

    2015-11-10

    In this study, we developed a novel direct tandem mass spectrometric method for rapid and accurate analysis of amino acids utilizing a fluorous derivatization and purification technique. Amino acids were perfluoroalkylated with 2H,2H,3H,3H-perfluoroundecan-1-al in the presence of 2-picoline borane via reductive amination. The derivatives were purified by perfluoroalkyl-modified silica-based monolithic solid-phase extraction (monolithic F-SPE), and directly analyzed by tandem mass spectrometry using electrospray ionization without liquid chromatographic separation. The perfluoroalkyl derivatives could be sufficiently distinguished from non-fluorous compounds, i.e. the biological matrix, due to their fluorous interaction. Thus, rapid and accurate determination of amino acids was accomplished. The method was validated with human plasma samples and applied to the analysis of amino acids in the plasma of mice with maple syrup urine disease or phenylketonuria.

  16. Immunopurification and mass spectrometric quantification of the active form of a chimeric therapeutic antibody in human serum.

    PubMed

    Dubois, Mathieu; Fenaille, François; Clement, Gilles; Lechmann, Martin; Tabet, Jean-Claude; Ezan, Eric; Becher, François

    2008-03-01

    In this study, we show that liquid chromatography coupled with tandem mass spectrometry provides a sensitive, specific, and accurate absolute quantification of Erbitux, a human:murine chimeric mAb used for the treatment of colorectal cancer. Micrometric magnetized beads, functionalized with soluble epidermal growth factor receptor (sEGFR), the pharmacological target of Erbitux, were used for specific immunocapture of Erbitux allowing assessment of the antibody's biological potency and sample purification. Following digestion with trypsin, specific peptides from light and heavy chains were monitored in the selected reaction monitoring (SRM) mode. Assay variability below 20% was provided through optimization of the digestion step and rigorous monitoring of the whole analytical process using an appropriate internal standard. The 20 ng/mL lower limit of quantification was similar to that of ELISA methods. These results show that this mass spectrometric approach is a potential alternative for pharmacokinetic evaluation of mAbs during clinical development.

  17. Mass spectrometric monitoring of the degradation and elimination efficiency for hardly eliminable and hardly biodegradable polar compounds by membrane bioreactors.

    PubMed

    Schröder, H Fr

    2002-01-01

    Wastewaters containing or spiked with polar compounds--alkylphenolethoxylates (APEOs) and drugs--were treated in membrane-assisted and conventional biological pilot plants to eliminate these pollutants. Elimination resulting in metabolization or ultimate degradation was pursued by substance-specific analysis applying atmospheric pressure chemical ionization (APCI) in combination with mass and tandem mass spectrometric detection (MS and MS-MS) either in the flow injection (FIA) or liquid chromatographic separation (LC) mode. APEOs were diminished by successive cleavage of polyether chain links resulting in short chain APEOs or alkylphenols (AP), if the biocoenosis was adapted to the compounds. Lipid regulating agents (LRA) were either eliminated completely (etofibrate), metabolized to fenofibratic acid (fenofibrate) or diminished to a minimal extent (bezafibrate). Compared to the membrane microfiltration process the conventional activated sludge process was less successful in both APEO and LRA elimination.

  18. Normal phase liquid chromatography coupled to quadrupole time of flight atmospheric pressure chemical ionization mass spectrometry for separation, detection and mass spectrometric profiling of neutral sphingolipids and cholesterol.

    PubMed

    Farwanah, Hany; Wirtz, Jennifer; Kolter, Thomas; Raith, Klaus; Neubert, Reinhard H H; Sandhoff, Konrad

    2009-10-01

    Many lipidomic approaches focus on investigating aspects of sphingolipid metabolism. Special emphasis is put on neutral sphingolipids and cholesterol and their interaction. Such an interest is attributed to the fact that those lipids are altered in a series of serious disorders including various sphingolipidoses. High performance thin-layer chromatography (HPTLC) has become a widely used technique for lipid analysis. However, mass spectrometric profiling is irreplaceable for gaining an overview about the various molecular species within a lipid class. In this work we have developed a sensitive method based on a gradient normal phase high performance liquid chromatography (HPLC) coupled to quadrupole time of flight (QTOF) atmospheric pressure chemical ionization mass spectrometry (APCI-MS) in positive mode, which for the first time enables separation, on-line detection, and mass spectrometric profiling of multiple neutral sphingolipids including ceramide, glucosylceramide, lactosylceramide, globotriaosylceramide, globotetraosylceramide, sphingomyelin as well as cholesterol within less than 15min. An important advantage of the presented HPLC/APCI-MS approach is that the separation pattern emulates the one obtained by an optimized HPTLC method with a multiple stage development. Thus, the lipid classes previously separated and quantified by HPTLC can be easily screened regarding their mass spectrometric profiles by HPLC/APCI-MS. In addition, the selected ionization conditions enable in-source fragmentation providing useful structural information. The methods (HPLC/APCI-MS and the optimized HPTLC) were applied for the analysis of the mentioned lipids in human fibroblasts. This approach is aimed basically at investigators who perform studies based on genetic modifications or treatment with pharmacological agents leading to changes in the biochemical pathways of neutral sphingolipids and cholesterol. In addition, it can be of interest for research on disorders related to

  19. Mass Spectrometric Analysis of Spatio-Temporal Dynamics of Crustacean Neuropeptides

    PubMed Central

    OuYang, Chuanzi; Liang, Zhidan; Li, Lingjun

    2014-01-01

    Neuropeptides represent one of the largest classes of signaling molecules used by nervous systems to regulate a wide range of physiological processes. Over the past several years, mass spectrometry (MS)-based strategies have revolutionized the discovery of neuropeptides in numerous model organisms, especially in decapod crustaceans. Here, we focus our discussion on recent advances in the use of MS-based techniques to map neuropeptides in spatial domain and monitoring their dynamic changes in temporal domain. These MS-enabled investigations provide valuable information about the distribution, secretion and potential function of neuropeptides with high molecular specificity and sensitivity. In situ MS imaging and in vivo microdialysis are highlighted as key technologies for probing spatio-temporal dynamics of neuropeptides in the crustacean nervous system. This review summarizes the latest advancement in MS-based methodologies for neuropeptide analysis including typical workflow and sample preparation strategies as well as major neuropeptide families discovered in decapod crustaceans. PMID:25448012

  20. ESR and mass-spectrometric uranium-series dating studies of a mammoth tooth from stanton harcourt, Oxfordshire, England

    NASA Astrophysics Data System (ADS)

    Zhou, L. P.; McDermott, F.; Rhodes, E. J.; Marseglia, E. A.; Mellars, P. A.

    The age of the Channel Deposits at Stanton Harcourt, Oxfordshire, England, has been a topic of debate with important implications for British Pleistocene stratigraphy. Recent excavations led by K. Scott reveal ample evidence for ancient environmental conditions characteristic of an interglacial. However, the question remains on the assignment of its age. At present it is thought to represent an interglacial corresponding to either marine OI Stage 7 or 5e. In an attempt to constrain the chronology of the site, and to assess the techniques' reliability, we have made electron spin resonance (ESR) measurements on enamel and mass-spectrometric U-series measurements on both enamel and dentine from a mammoth tooth buried in the Channel Deposits at Stanton Harcourt. Four dentine samples gave U-series dates between 65.4±0.4 and 146.5±1.0 ka and two enamel samples between these dentine layers were dated to 53.3±0.2 and 61.1±0.6 ka. The corresponding ESR age estimates for the enamel samples are 59±6 and 62±4 ka (early U-uptake, EU) and 95±11 and 98±7 ka (linear U-uptake, LU). The recent U-uptake (RU) dates are 245±38 and 238±31 ka, but in light of the U-series data we would not expect these to represent realistic age estimates. Similar ESR results were obtained from two other adjacent enamel samples. The effect of the large size of the mammoth tooth on the external gamma dose, and the internal gamma contribution from the high U content of the dentine, are considered. While the recent uptake ESR dates appear to coincide with OI Stage 7, all the early and linear uptake ESR and mass-spectrometric U-series dates are younger than the expected age estimation based on recent geological interpretation and amino acid racemisation measurements (>200 ka) and optical dating studies (200-450 ka). Possible causes of the unexpected dating results are discussed. We conclude that our mass-spectrometric U-series and EU and LU ESR measurements represent minimum age estimates for the

  1. Large-scale mass spectrometric detection of variant peptides resulting from non-synonymous nucleotide differences

    PubMed Central

    Sheynkman, Gloria M.; Shortreed, Michael R.; Frey, Brian L.; Scalf, Mark; Smith, Lloyd M.

    2013-01-01

    Each individual carries thousands of non-synonymous single nucleotide variants (nsSNVs) in their genome, each corresponding to a single amino acid polymorphism (SAP) in the encoded proteins. It is important to be able to directly detect and quantify these variations at the protein level in order to study post-transcriptional regulation, differential allelic expression, and other important biological processes. However, such variant peptides are not generally detected in standard proteomic analyses, due to their absence from the generic databases that are employed for mass spectrometry searching. Here, we extend previous work that demonstrated the use of customized SAP databases constructed from sample-matched RNA-Seq data. We collected deep coverage RNA-Seq data from the Jurkat cell line, compiled the set of nsSNVs that are expressed, used this information to construct a customized SAP database, and searched it against deep coverage shotgun MS data obtained from the same sample. This approach enabled detection of 421 SAP peptides mapping to 395 nsSNVs. We compared these peptides to peptides identified from a large generic search database containing all known nsSNVs (dbSNP) and found that more than 70% of the SAP peptides from this dbSNP-derived search were not supported by the RNA-Seq data, and thus are likely false positives. Next, we increased the SAP coverage from the RNA-Seq derived database by utilizing multiple protease digestions, thereby increasing variant detection to 695 SAP peptides mapping to 504 nsSNV sites. These detected SAP peptides corresponded to moderate to high abundance transcripts (30+ transcripts per million, TPM). The SAP peptides included 192 allelic pairs; the relative expression levels of the two alleles were evaluated for 51 of those pairs, and found to be comparable in all cases. PMID:24175627

  2. Differentiation of the two major species of Echinacea (E. augustifolia and E. purpurea) using a flow injection mass spectrometric (FIMS) fingerprinting method and chemometric analysis

    USDA-ARS?s Scientific Manuscript database

    A rapid, simple, and reliable flow-injection mass spectrometric (FIMS) method was developed to discriminate two major Echinacea species (E. purpurea and E. angustifolia) samples. Fifty-eight Echinacea samples collected from United States were analyzed using FIMS. Principle component analysis (PCA) a...

  3. Utility of spatially-resolved atmospheric pressure surface sampling and ionization techniques as alternatives to mass spectrometric imaging (MSI) in drug metabolism

    SciTech Connect

    Blatherwick, Eleanor Q.; Van Berkel, Gary J; Pickup, Kathryn; Johansson, Maria K.; Beaudoin, Marie-Eve; Cole, Roderic; Day, Jennifer M.; Iverson, Suzanne; Wilson, Ian D.; Scrivens, James H.; Weston, Daniel J.

    2011-01-01

    1. Tissue distribution studies of drug molecules play an essential role in the pharmaceutical industry and are commonly undertaken using quantitative whole body autoradiography (QWBA) methods. 2. The growing need for complementary methods to address some scientific gaps around radiography methods has led to increased use of mass spectrometric imaging (MSI) technology over the last 5 to 10 years. More recently, the development of novel mass spectrometric techniques for ambient surface sampling has redefined what can be regarded as fit-for-purpose for MSI in a drug metabolism and disposition arena. 3. Together with a review of these novel alternatives, this paper details the use of two liquid microjunction (LMJ)- based mass spectrometric surface sampling technologies. These approaches are used to provide qualitative determination of parent drug in rat liver tissue slices using liquid extraction surface analysis (LESA) and to assess the performance of a LMJ surface sampling probe (LMJ-SSP) interface for quantitative assessment of parent drug in brain, liver and muscle tissue slices. 4. An assessment of the utility of these spatially-resolved sampling methods is given, showing interdependence between mass spectrometric and QWBA methods, in particular there emerges a reason to question typical MSI workflows for drug metabolism; suggesting the expedient use of profile or region analysis may be more appropriate, rather than generating time-intensive molecular images of the entire tissue section.

  4. INTERLABORATORY STUDY OF A THERMOSPRAY-LIQUID CHROMATOGRAPHIC/MASS SPECTROMETRIC METHOD FOR SELECTED N-METHYL CARBAMATES, N-METHYL CARBAMOYLOXIMES, AND SUBSTITUTED UREA PESTICIDES

    EPA Science Inventory

    A thermospray-liquid chromatographic/mass spectrometric (TS-LC/MS) method was evaluated in an interlaboratory study for determining 3 N-methyl carbamates (bendiocarb, carbaryl, and carbofuran), 3-N-methyl carbamoyloximes (aldicarb, methomyl, and oxamyl), 2 substituted urea pestic...

  5. INTERLABORATORY STUDY OF A THERMOSPRAY-LIQUID CHROMATOGRAPHIC/MASS SPECTROMETRIC METHOD FOR SELECTED N-METHYL CARBAMATES, N-METHYL CARBAMOYLOXIMES, AND SUBSTITUTED UREA PESTICIDES

    EPA Science Inventory

    A thermospray-liquid chromatographic/mass spectrometric (TS-LC/MS) method was evaluated in an interlaboratory study for determining 3 N-methyl carbamates (bendiocarb, carbaryl, and carbofuran), 3-N-methyl carbamoyloximes (aldicarb, methomyl, and oxamyl), 2 substituted urea pestic...

  6. Utility of spatially-resolved atmospheric pressure surface sampling and ionization techniques as alternatives to mass spectrometric imaging (MSI) in drug metabolism.

    PubMed

    Blatherwick, Eleanor Q; Van Berkel, Gary J; Pickup, Kathryn; Johansson, Maria K; Beaudoin, Marie-Eve; Cole, Roderic O; Day, Jennifer M; Iverson, Suzanne; Wilson, Ian D; Scrivens, James H; Weston, Daniel J

    2011-08-01

    Tissue distribution studies of drug molecules play an essential role in the pharmaceutical industry and are commonly undertaken using quantitative whole body autoradiography (QWBA) methods. The growing need for complementary methods to address some scientific gaps around radiography methods has led to increased use of mass spectrometric imaging (MSI) technology over the last 5 to 10 years. More recently, the development of novel mass spectrometric techniques for ambient surface sampling has redefined what can be regarded as "fit-for-purpose" for MSI in a drug metabolism and disposition arena. Together with a review of these novel alternatives, this paper details the use of two liquid microjunction (LMJ)-based mass spectrometric surface sampling technologies. These approaches are used to provide qualitative determination of parent drug in rat liver tissue slices using liquid extraction surface analysis (LESA) and to assess the performance of a LMJ surface sampling probe (LMJ-SSP) interface for quantitative assessment of parent drug in brain, liver and muscle tissue slices. An assessment of the utility of these spatially-resolved sampling methods is given, showing interdependence between mass spectrometric and QWBA methods, in particular there emerges a reason to question typical MSI workflows for drug metabolism; suggesting the expedient use of profile or region analysis may be more appropriate, rather than generating time-intensive molecular images of the entire tissue section.

  7. Differentiation of the four major types (C. Burmannii, C. Verum, C. cassia, And C. Loureiroi) of cinnamons using a flow-injection mass spectrometric (FIMS) fingerprinting method

    USDA-ARS?s Scientific Manuscript database

    A simple and efficient flow-injection mass spectrometric (FIMS) method was developed to differentiate cinnamon (Cinnamomum) bark (CB) samples of the four major species (C. burmannii, C. verum, C. aromaticum, and C. loureiroi) of cinnamon. Fifty cinnamon samples collected from China, Vietnam, Indon...

  8. [Characterization of inductive synthesis of levoglucosan kinase by a combined strategy of enzymological and fast atom bombardment mass spectrometric analysis].

    PubMed

    Zhuang, Xu-Liang; Zhang, Hong-Xun

    2002-09-01

    Levoglucosan is the main product derived from pyrolysis of cellulose. A mutant Aspergillus niger CBX-209 could grow on levoglucosan well fermenting it into citric acid with a yield comparable to that on glucose. Levoglucosan hydrolase was absent by measuring glucose formation with the glucose oxidase and peroxidase coupling system. Cell extracts were partly purified by ammonium sulfate fractionation and ion-exchange chromatograph. Direct formation of glucose 6-phosphate from levoglucosan in the presence of ATP and MgCl2 was observed when it was reacted with partly purified enzyme by a combined strategy of enzymological and fast atom bombardment mass spectrometric analysis. These data showed that the mutant used a novel enzyme, levoglucosan kinase, to convert levoglucosan into glucose 6-phosphate. Levoglucosan kinase was an inductive enzyme.

  9. Mass-spectrometric monitoring of the intravenous anesthetic concentration in the breathing circuit of an anesthesia machine

    NASA Astrophysics Data System (ADS)

    Elizarov, A. Yu.; Levshankov, A. I.

    2011-04-01

    Interaction between inhalational anesthetic sevoflurane and an absorber of CO2 (soda lime) in the breathing circuit of an anesthesia machine during low-flow anesthesia (0.5 l of a fresh gaseous mixture per minute) is studied with the mass-spectrometric method. Monitoring data for the concentration of sevoflurane and three toxic products of sevoflurane decompositions (substances A, B, and C) during anesthesia in the inspiration-expiration regime are presented. The highest concentration of substance A is found to be 65 ppm. The biochemical blood analysis before and after anesthesia shows that nephropathy is related to the function of liver toxicity. It is found that inhalational anesthetic sevoflurane influences the concentration of intravenous hypnotic propofol in blood.

  10. Structure and function in rhodopsin: Mass spectrometric identification of the abnormal intradiscal disulfide bond in misfolded retinitis pigmentosa mutants

    PubMed Central

    Hwa, John; Klein-Seetharaman, Judith; Khorana, H. Gobind

    2001-01-01

    Retinitis pigmentosa (RP) point mutations in both the intradiscal (ID) and transmembrane domains of rhodopsin cause partial or complete misfolding of rhodopsin, resulting in loss of 11-cis-retinal binding. Previous work has shown that misfolding is caused by the formation of a disulfide bond in the ID domain different from the native Cys-110–Cys-187 disulfide bond in native rhodopsin. Here we report on direct identification of the abnormal disulfide bond in misfolded RP mutants in the transmembrane domain by mass spectrometric analysis. This disulfide bond is between Cys-185 and Cys-187, the same as previously identified in misfolded RP mutations in the ID domain. The strategy described here should be generally applicable to identification of disulfide bonds in other integral membrane proteins. PMID:11320236

  11. Determination of norgestimate and its metabolites in human serum using high-performance liquid chromatography with tandem mass spectrometric detection.

    PubMed

    Wong, F A; Edom, R W; Duda, M; Tischio, J P; Huang, M; Juzwin, S; Tegegne, G

    1999-11-12

    A rapid and reliable analytical method is described for the simultaneous determination of a synthetic progestin norgestimate (NGM), and its metabolites, 17-deacetylnorgestimate (17-DA-NGM), 3-ketonorgestimate (3-keto-NGM) and norgestrel (NGL) in human serum using reversed phase high-performance liquid chromatography (HPLC) with tandem mass spectrometric (MS-MS) detection. The assay was linear over the concentration ranges of 0.1-5.0 ng/ml for 17-DA-NGM and NGL and 0.5-5.0 ng/ml for NGM and 3-keto-NGM. The inter-assay reproducibility was consistently less than 10%. The overall recovery of the analytes ranged from 72 to 92%. Serum profiles following oral administration of norgestimate to female volunteers are presented.

  12. Mass spectrometric 13C/12C determinations to detect high fructose corn syrup in orange juice: collaborative study.

    PubMed

    Doner, L W; Bills, D D; Carro, O; Drimmie, R; Fritz, P; Gearing, J N; Hillaire-Marcel, C; Parker, P L; Reeseman, F M; Smith, B N; Ziegler, H

    1982-05-01

    The 13C/12C ratios in orange juice are sufficiently uniform and different from those in high fructose corn syrup (HFCS) so that the addition of HFCS to orange juice can be detected. HFCS averages -9.7% (parts per thousand) delta 13C, orange juice averages -24.5%, and mixtures of HFCS and orange juice possess intermediate values. One pure orange juice and 4 orange juice -HFCS mixtures containing from 25 to 70% orange juice were properly classified by 7 collaborators. Samples with delta 13C values less negative than -22.1%, 4 standard deviations from the mean of pure juices, can, with a high degree of confidence, be classified as adulterated. Samples with values more negative than -22.1% must be considered unadulterated with HFCS, because pure orange juices possess a range of delta 13C values. The 13C/12C mass spectrometric method was adopted official first action for detecting HFCS in orange juice.

  13. mMass 3: a cross-platform software environment for precise analysis of mass spectrometric data.

    PubMed

    Strohalm, Martin; Kavan, Daniel; Novák, Petr; Volný, Michael; Havlícek, Vladimír

    2010-06-01

    While tools for the automated analysis of MS and LC-MS/MS data are continuously improving, it is still often the case that at the end of an experiment, the mass spectrometrist will spend time carefully examining individual spectra. Current software support is mostly provided only by the instrument vendors, and the available software tools are often instrument-dependent. Here we present a new generation of mMass, a cross-platform environment for the precise analysis of individual mass spectra. The software covers a wide range of processing tasks such as import from various data formats, smoothing, baseline correction, peak picking, deisotoping, charge determination, and recalibration. Functions presented in the earlier versions such as in silico digestion and fragmentation were redesigned and improved. In addition to Mascot, an interface for ProFound has been implemented. A specific tool is available for isotopic pattern modeling to enable precise data validation. The largest available lipid database (from the LIPID MAPS Consortium) has been incorporated and together with the new compound search tool lipids can be rapidly identified. In addition, the user can define custom libraries of compounds and use them analogously. The new version of mMass is based on a stand-alone Python library, which provides the basic functionality for data processing and interpretation. This library can serve as a good starting point for other developers in their projects. Binary distributions of mMass, its source code, a detailed user's guide, and video tutorials are freely available from www.mmass.org .

  14. Texture mapping via optimal mass transport.

    PubMed

    Dominitz, Ayelet; Tannenbaum, Allen

    2010-01-01

    In this paper, we present a novel method for texture mapping of closed surfaces. Our method is based on the technique of optimal mass transport (also known as the "earth-mover's metric"). This is a classical problem that concerns determining the optimal way, in the sense of minimal transportation cost, of moving a pile of soil from one site to another. In our context, the resulting mapping is area preserving and minimizes angle distortion in the optimal mass sense. Indeed, we first begin with an angle-preserving mapping (which may greatly distort area) and then correct it using the mass transport procedure derived via a certain gradient flow. In order to obtain fast convergence to the optimal mapping, we incorporate a multiresolution scheme into our flow. We also use ideas from discrete exterior calculus in our computations.

  15. Texture Mapping via Optimal Mass Transport

    PubMed Central

    Dominitz, Ayelet; Tannenbaum, Allen

    2010-01-01

    In this paper, we present a novel method for texture mapping of closed surfaces. Our method is based on the technique of optimal mass transport (also known as the “earth-mover’s metric”). This is a classical problem that concerns determining the optimal way, in the sense of minimal transportation cost, of moving a pile of soil from one site to another. In our context, the resulting mapping is area preserving and minimizes angle distortion in the optimal mass sense. Indeed, we first begin with an angle-preserving mapping (which may greatly distort area) and then correct it using the mass transport procedure derived via a certain gradient flow. In order to obtain fast convergence to the optimal mapping, we incorporate a multiresolution scheme into our flow. We also use ideas from discrete exterior calculus in our computations. PMID:20224137

  16. A microchip electrophoresis-mass spectrometric platform with double cell lysis nano-electrodes for automated single cell analysis.

    PubMed

    Li, Xiangtang; Zhao, Shulin; Hu, Hankun; Liu, Yi-Ming

    2016-06-17

    Capillary electrophoresis-based single cell analysis has become an essential approach in researches at the cellular level. However, automation of single cell analysis has been a challenge due to the difficulty to control the number of cells injected and the irreproducibility associated with cell aggregation. Herein we report the development of a new microfluidic platform deploying the double nano-electrode cell lysis technique for automated analysis of single cells with mass spectrometric detection. The proposed microfluidic chip features integration of a cell-sized high voltage zone for quick single cell lysis, a microfluidic channel for electrophoretic separation, and a nanoelectrospray emitter for ionization in MS detection. Built upon this platform, a microchip electrophoresis-mass spectrometric method (MCE-MS) has been developed for automated single cell analysis. In the method, cell introduction, cell lysis, and MCE-MS separation are computer controlled and integrated as a cycle into consecutive assays. Analysis of large numbers of individual PC-12 neuronal cells (both intact and exposed to 25mM KCl) was carried out to determine intracellular levels of dopamine (DA) and glutamic acid (Glu). It was found that DA content in PC-12 cells was higher than Glu content, and both varied from cell to cell. The ratio of intracellular DA to Glu was 4.20±0.8 (n=150). Interestingly, the ratio drastically decreased to 0.38±0.20 (n=150) after the cells are exposed to 25mM KCl for 8min, suggesting the cells released DA promptly and heavily while they released Glu at a much slower pace in response to KCl-induced depolarization. These results indicate that the proposed MCE-MS analytical platform may have a great potential in researches at the cellular level. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Mass spectrometric identification of proteins that interact through specific domains of the poly(A) binding protein

    PubMed Central

    Zhang, Chongxu; Nielsen, Maria E. O.; Chiang, Yueh-Chin; Kierkegaard, Morten; Wang, Xin; Lee, Darren J.; Andersen, Jens S.; Yao, Gang

    2013-01-01

    Poly(A) binding protein (PAB1) is involved in a number of RNA metabolic functions in eukaryotic cells and correspondingly is suggested to associate with a number of proteins. We have used mass spectrometric analysis to identify 55 non-ribosomal proteins that specifically interact with PAB1 from Saccharomyces cerevisiae. Because many of these factors may associate only indirectly with PAB1 by being components of the PAB1-mRNP structure, we additionally conducted mass spectrometric analyses on seven metabolically defined PAB1 deletion derivatives to delimit the interactions between these proteins and PAB1. These latter analyses identified 13 proteins whose associations with PAB1 were reduced by deleting one or another of PAB1’s defined domains. Included in this list of 13 proteins were the translation initiation factors eIF4G1 and eIF4G2, translation termination factor eRF3, and PBP2, all of whose previously known direct interactions with specific PAB1 domains were either confirmed, delimited, or extended. The remaining nine proteins that interacted through a specific PAB1 domain were CBF5, SLF1, UPF1, CBC1, SSD1, NOP77, yGR250c, NAB6, and GBP2. In further study, UPF1, involved in nonsense-mediated decay, was confirmed to interact with PAB1 through the RRM1 domain. We additionally established that while the RRM1 domain of PAB1 was required for UPF1-induced acceleration of deadenylation during nonsense-mediated decay, it was not required for the more critical step of acceleration of mRNA decapping. These results begin to identify the proteins most likely to interact with PAB1 and the domains of PAB1 through which these contacts are made. PMID:22836166

  18. Mass spectrometric identification of proteins that interact through specific domains of the poly(A) binding protein.

    PubMed

    Richardson, Roy; Denis, Clyde L; Zhang, Chongxu; Nielsen, Maria E O; Chiang, Yueh-Chin; Kierkegaard, Morten; Wang, Xin; Lee, Darren J; Andersen, Jens S; Yao, Gang

    2012-09-01

    Poly(A) binding protein (PAB1) is involved in a number of RNA metabolic functions in eukaryotic cells and correspondingly is suggested to associate with a number of proteins. We have used mass spectrometric analysis to identify 55 non-ribosomal proteins that specifically interact with PAB1 from Saccharomyces cerevisiae. Because many of these factors may associate only indirectly with PAB1 by being components of the PAB1-mRNP structure, we additionally conducted mass spectrometric analyses on seven metabolically defined PAB1 deletion derivatives to delimit the interactions between these proteins and PAB1. These latter analyses identified 13 proteins whose associations with PAB1 were reduced by deleting one or another of PAB1's defined domains. Included in this list of 13 proteins were the translation initiation factors eIF4G1 and eIF4G2, translation termination factor eRF3, and PBP2, all of whose previously known direct interactions with specific PAB1 domains were either confirmed, delimited, or extended. The remaining nine proteins that interacted through a specific PAB1 domain were CBF5, SLF1, UPF1, CBC1, SSD1, NOP77, yGR250c, NAB6, and GBP2. In further study, UPF1, involved in nonsense-mediated decay, was confirmed to interact with PAB1 through the RRM1 domain. We additionally established that while the RRM1 domain of PAB1 was required for UPF1-induced acceleration of deadenylation during nonsense-mediated decay, it was not required for the more critical step of acceleration of mRNA decapping. These results begin to identify the proteins most likely to interact with PAB1 and the domains of PAB1 through which these contacts are made.

  19. A microchip electrophoresis-mass spectrometric platform with double cell lysis nano-electrodes for automated single cell analysis

    PubMed Central

    Li, Xiangtang; Zhao, Shulin; Hu, Hankun; Liu, Yi-Ming

    2016-01-01

    Capillary electrophoresis-based single cell analysis has become an essential approach in researches at the cellular level. However, automation of single cell analysis has been a challenge due to the difficulty to control the number of cells injected and the irreproducibility associated with cell aggregation. Herein we report the development of a new microfluidic platform deploying the double nano-electrode cell lysis technique for automated analysis of single cells with mass spectrometric detection. The proposed microfluidic chip features integration of a cell-sized high voltage zone for quick single cell lysis, a microfluidic channel for electrophoretic separation, and a nanoelectrospray emitter for ionization in MS detection. Built upon this platform, a microchip electrophoresis - mass spectrometric method (MCE-MS) has been developed for automated single cell analysis. In the method, cell introduction, cell lysis, and MCE-MS separation are computer controlled and integrated as a cycle into consecutive assays. Analysis of large numbers of individual PC-12 neuronal cells (both intact and exposed to 25 mM KCl) was carried out to determine intracellular levels of dopamine (DA) and glutamic acid (Glu). It was found that DA content in PC-12 cells was higher than Glu content, and both varied from cell to cell. The ratio of intracellular DA to Glu was 4.20 ± 0.8 (n=150). Interestingly, the ratio drastically decreased to 0.38 ± 0.20 (n= 150) after the cells are exposed to 25 mM KCl for 8 min, suggesting the cells released DA promptly and heavily while they released Glu at a much slower pace in response to KCl-induced depolarization. These results indicate that the proposed MCE-MS analytical platform may have a great potential in researches at the cellular level. PMID:27207575

  20. Mass spectrometric analysis of spatio-temporal dynamics of crustacean neuropeptides.

    PubMed

    OuYang, Chuanzi; Liang, Zhidan; Li, Lingjun

    2015-07-01

    Neuropeptides represent one of the largest classes of signaling molecules used by nervous systems to regulate a wide range of physiological processes. Over the past several years, mass spectrometry (MS)-based strategies have revolutionized the discovery of neuropeptides in numerous model organisms, especially in decapod crustaceans. Here, we focus our discussion on recent advances in the use of MS-based techniques to map neuropeptides in the spatial domain and monitoring their dynamic changes in the temporal domain. These MS-enabled investigations provide valuable information about the distribution, secretion and potential function of neuropeptides with high molecular specificity and sensitivity. In situ MS imaging and in vivo microdialysis are highlighted as key technologies for probing spatio-temporal dynamics of neuropeptides in the crustacean nervous system. This review summarizes the latest advancement in MS-based methodologies for neuropeptide analysis including typical workflow and sample preparation strategies as well as major neuropeptide families discovered in decapod crustaceans. This article is part of a Special Issue entitled: Neuroproteomics: Applications in Neuroscience and Neurology. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Mass spectrometric detection of CP4 EPSPS in genetically modified soya and maize.

    PubMed

    Ocaña, Mireia Fernández; Fraser, Paul D; Patel, Raj K P; Halket, John M; Bramley, Peter M

    2007-01-01

    The potential of protein fractionation hyphenated to mass spectrometry (MS) to detect and characterize the transgenic protein present in Roundup Ready soya and maize has been investigated. Genetically modified (GM) soya and maize contain the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene from Agrobacterium tumefaciens CP4, which confers resistance to the herbicide glyphosate. The GM soya and maize proteomes were fractionated by gel filtration, anion-exchange chromatography and sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE) prior to MS. This facilitated detection of a tryptic peptide map of CP4 EPSPS by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS and nanoelectrospray ionization quadrupole time-of-flight (nanoESI-QTOF) MS. Subsequently, sequence information from the CP4 EPSPS tryptic peptides was obtained by nanoESI-QTOF MS/MS. The identification was accomplished in 0.9% GM soya seeds, which is the current EU threshold for food-labeling requirements.

  2. Structural characterization of arabinoxylans from two African plant species Eragrostis nindensis and Eragrostis tef using various mass spectrometric methods.

    PubMed

    Plancot, Barbara; Vanier, Gaëtan; Maire, Florian; Bardor, Muriel; Lerouge, Patrice; Farrant, Jill M; Moore, John; Driouich, Azeddine; Vicré-Gibouin, Maïté; Afonso, Carlos; Loutelier-Bourhis, Corinne

    2014-04-30

    The arabinoxylans are one of the main components of plant cell walls and are known to play major roles in plant tissues properties depending in particular on their structural features. It has been recently shown that one of the strategies developed by resurrection plants to overcome dehydration is based on cell wall composition. For this purpose, the structural characterization of arabinoxylans from desiccation-tolerant grass Eragrostis nindensis (E. nindensis) was compared with its close relative, the desiccation-sensitive Eragrostis tef (E. tef) in order to further understand mechansism of desiccation tolerance in resurrection plants. Ion mobility spectrometry coupled to mass spectrometry (IM-MS) in combination with the conventional mass spectrometric approaches, including matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS), electrospray ionization multistage tandem mass spectrometry (ESI-MS(n)) and gas chromatography/mass spectrometry (GC/MS), were used to characterize arabinoxylan fragments obtained after endo-xylanase digestion of leave extracts from E. nindensis and E. tef. Whole fingerprinting by MALDI-MS analysis showed the presence of various arabinoxylan fragments within leaves of E. nindensis and E. tef. The monosaccharide composition and some linkage information were determined by GC/MS experiments. Information regarding the branching and sequence details was obtained by ESI-MS(n) experiments after sample permethylation. The presence of structural isomeric ions with different collision cross sections was evidenced by IM-MS which could be differentiated using ESI-MS(n). We have shown that an orthogonal approach, and especially IM-MS associated to ESI-MS(n) (n = 2 to 4) and GC/MS allowed characterization of arabinoxylan fragments of E. nindensis and E. tef and revealed the presence of isomeric structures. The same arabinoxylan structures were identified for both species but in different relative abundance. Moreover, this work

  3. Application of mass spectrometric techniques for the trace analysis of short-lived iodine-containing volatiles emitted by seaweed.

    PubMed

    Kundel, Michael; Thorenz, Ute R; Petersen, Jan H; Huang, Ru-Jin; Bings, Nicolas H; Hoffmann, Thorsten

    2012-04-01

    Knowledge of the composition and emission rates of iodine-containing volatiles from major widespread seaweed species is important for modeling the impact of halogens on gas-phase atmospheric chemistry, new particle formation, and climate. In this work, we present the application of mass spectrometric techniques for the quantification of short-lived iodine-containing volatiles emitted by eight different seaweeds from the intertidal zone of Helgoland, Germany. A previously developed online time-of-flight aerosol mass spectrometric method was used to determine I(2) emission rates and investigate temporally resolved emission profiles. Simultaneously, iodocarbons were preconcentrated on solid adsorbent tubes and quantified offline using thermodesorption-gas chromatography-mass spectrometry. The total iodine content of the seaweeds was determined using microwave-assisted tetramethylammonium hydroxide extraction followed by inductively coupled-plasma mass spectrometry analysis. The highest total iodine content was found in the Laminariales, followed by the brown algae Ascophyllum nodosum, Fucus vesiculosus, Fucus serratus, and both red algae Chondrus crispus and Delesseria sanguinea. Laminariales were found to be the strongest I(2) emitters. Time series of the iodine release of Laminaria digitata and Laminaria hyperborea showed a strong initial I(2) emission when first exposed to air followed by an exponential decline of the release rate. For both species, I(2) emission bursts were observed. For Laminaria saccharina und F. serratus, a more continuous I(2) release profile was detected, however, F. serratus released much less I(2). A. nodosum and F. vesiculosus showed a completely different emission behavior. The I(2) emission rates of these species were slowly increasing with time during the first 1 to 2 h until a more or less stable I(2) emission rate was reached. The lowest I(2) emission rates were detected for the red algae C. crispus and D. sanguinea. Total iodocarbon

  4. Site-Specific Hydrogen Isotope Composition of Propane: Mass spectrometric methods, equilibrium temperature dependence, and kinetics of exchange

    NASA Astrophysics Data System (ADS)

    Xie, H.; Ponton, C.; Kitchen, N.; Lloyd, M. K.; Lawson, M.; Formolo, M. J.; Eiler, J. M.

    2016-12-01

    -specific thermometer; these experiments also provide a reference frame for reporting mass spectrometric data. Differential H-exchange rates of the two molecular sites in propane could be a new tool to constrain thermal history of sub-surface propane. Our experimental and mass spectrometric approaches should be generalizable to other hydrocarbon compounds.

  5. Distribution of coniferin in differentiating normal and compression woods using MALDI mass spectrometric imaging coupled with osmium tetroxide vapor treatment.

    PubMed

    Yoshinaga, Arata; Kamitakahara, Hiroshi; Takabe, Keiji

    2016-05-01

    Matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI) was employed to detect monolignol glucosides in differentiating normal and compression woods of two Japanese softwoods, Chamaecyparis obtusa and Cryptomeria japonica Comparison of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry collision-induced dissociation fragmentation analysis and structural time-of-flight (MALDI-TOF CID-FAST) spectra between coniferin and differentiating xylem also confirmed the presence of coniferin in differentiating xylem. However, as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and MALDI-TOF CID-FAST spectra of sucrose were similar to those of coniferin, it was difficult to distinguish the distribution of coniferin and sucrose using MALDI-MSI and collision-induced dissociation measurement only. To solve this problem, osmium tetroxide vapor was applied to sections of differentiating xylem. This vapor treatment caused peak shifts corresponding to the introduction of two hydroxyl groups to the C=C double bond in coniferin. The treatment did not cause a peak shift for sucrose, and therefore was effective in distinguishing coniferin and sucrose. Thus, it was found that MALDI-MSI combined with osmium tetroxide vapor treatment is a useful method to detect coniferin in differentiating xylem.

  6. Interferometric Mapping of Perseus Outflows with MASSES

    NASA Astrophysics Data System (ADS)

    Stephens, Ian; Dunham, Michael; Myers, Philip C.; MASSES Team

    2017-01-01

    The MASSES (Mass Assembly of Stellar Systems and their Evolution with the SMA) survey, a Submillimeter Array (SMA) large-scale program, is mapping molecular lines and continuum emission about the 75 known Class 0/I sources in the Perseus Molecular Cloud. In this talk, I present some of the key results of this project, with a focus on the CO(2-1) maps of the molecular outflows. In particular, I investigate how protostars inherit their rotation axes from large-scale magnetic fields and filamentary structure.

  7. Mass Spectral Investigations on Toxins. 2. Simultaneous Detection and Quantification of Ultra-Trace Levels of Simple Trichothecenes in Environmental and Fermentation Samples by Gas Chromatographic/Negative Ion Chemical Ionization-Mass Spectrometric Techniques

    DTIC Science & Technology

    1987-01-01

    number) FIELD GROUP SUB-GRO Toxins Derivatization Gas chromatography 15 02 Trichothecenes Negative ion Mass spectrometry "N Mycotoxins Chemical ionization...method for simultnnnously detecting and quantifying several simple trichothecene mycotoxins and related molecules has been developed. The method...FERMENTATION SAMPLES BY GAS CHROMATOGRAPHIC/NEGATIVE ION CHEMICAL IONIZATION-MASS SPECTROMETRIC TECHNIQUES 1. IINTRODUCTION Trichothecene mycotoxins

  8. Metallobiological necklaces: mass spectrometric and molecular modeling study of metallation in concatenated domains of metallothionein.

    PubMed

    Chan, Jayna; Huang, Zuyun; Watt, Ian; Kille, Peter; Stillman, Martin

    2008-01-01

    The ubiquitous protein metallothionein (MT) has proven to be a major player not only in the homeostasis of Cu(I) and Zn(II), but also binds all the Group 11 and 12 metals. Metallothioneins are characterised by the presence of numerous cys-x-cys and cys-cys motifs in the sequence and are found naturally with either one domain or two, linked, metal-binding domains. The use of chains of these metal-thiolate domains offers the possibility of creating chemically tuneable and, therefore, chemically dependent electrochemical or photochemical surface modifiers or as nanomachinery with nanomechanical properties. In this work, the metal-binding properties of the Cd(4)-containing domain of alpha-rhMT1a assembled into chains of two and three concatenated domains, that is, "necklaces", have been studied by spectrometric techniques, and the interactions within the structures modelled and interpreted by using molecular dynamics. These chains are metallated with 4, 8 or 12 Cd(II) ions to the 11, 22, and 33 cysteinyl sulfur atoms in the alpha-rhMT1a, alphaalpha-rhMT1a, and alphaalphaalpha-rhMT1a proteins, respectively. The effect of pH on the folding of each protein was studied by ESI-MS and optical spectroscopy. MM3/MD simulations were carried out over a period of up to 500 ps by using force-field parameters based on the reported structural data. These calculations provide novel information about the motion of the clustered metallated, partially demetallated, and metal-free peptide chains, with special interest in the region of the metal-binding site. The MD energy/time trajectory conformations show for the first time the flexibility of the metal-sulfur clusters and the bound amino acid chains. We report unexpected and very different sizes for the metallated and demetallated proteins from the combination of experimental data, with molecular dynamics simulations.

  9. A NEW MASS SPECTROMETRIC TECHNIQUE FOR IDENTIFYING TRACE-LEVEL ORGANIC COMPOUNDS IN COMPLEX MIXTURES

    EPA Science Inventory



    Most organic compounds are not found in mass spectral libraries and cannot be easily identified from low resolution mass spectra. Ion Composition Elucidation (ICE) utilizes selected ion recording with a double focusing mass spectrometer in a new way to determine exact mas...

  10. A NEW MASS SPECTROMETRIC TECHNIQUE FOR IDENTIFYING TRACE-LEVEL ORGANIC COMPOUNDS IN COMPLEX MIXTURES

    EPA Science Inventory



    Most organic compounds are not found in mass spectral libraries and cannot be easily identified from low resolution mass spectra. Ion Composition Elucidation (ICE) utilizes selected ion recording with a double focusing mass spectrometer in a new way to determine exact mas...

  11. Development of high-spatial and high-mass resolution mass spectrometric imaging (MSI) and its application to the study of small metabolites and endogenous molecules of plants

    SciTech Connect

    Jun, Ji Hyun

    2012-01-01

    High-spatial and high-mass resolution laser desorption ionization (LDI) mass spectrometric (MS) imaging technology was developed for the attainment of MS images of higher quality containing more information on the relevant cellular and molecular biology in unprecedented depth. The distribution of plant metabolites is asymmetric throughout the cells and tissues, and therefore the increase in the spatial resolution was pursued to reveal the localization of plant metabolites at the cellular level by MS imaging. For achieving high-spatial resolution, the laser beam size was reduced by utilizing an optical fiber with small core diameter (25 μm) in a vacuum matrix-assisted laser desorption ionization-linear ion trap (vMALDI-LTQ) mass spectrometer. Matrix application was greatly improved using oscillating capillary nebulizer. As a result, single cell level spatial resolution of ~ 12 μm was achieved. MS imaging at this high spatial resolution was directly applied to a whole Arabidopsis flower and the substructures of an anther and single pollen grains at the stigma and anther were successfully visualized. MS imaging of high spatial resolution was also demonstrated to the secondary roots of Arabidopsis thaliana and a high degree of localization of detected metabolites was successfully unveiled. This was the first MS imaging on the root for molecular species. MS imaging with high mass resolution was also achieved by utilizing the LTQ-Orbitrap mass spectrometer for the direct identification of the surface metabolites on the Arabidopsis stem and root and differentiation of isobaric ions having the same nominal mass with no need of tandem mass spectrometry (MS/MS). MS imaging at high-spatial and high-mass resolution was also applied to cer1 mutant of the model system Arabidopsis thaliana to demonstrate its usefulness in biological studies and reveal associated metabolite changes in terms of spatial distribution and/or abundances compared to those of wild-type. The spatial

  12. Improved matrix-assisted laser desorption/ionization mass spectrometric detection of glycosaminoglycan disaccharides as cesium salts.

    PubMed

    Laremore, Tatiana N; Linhardt, Robert J

    2007-01-01

    Ultraviolet matrix-assisted laser desorption/ionization mass spectrometric (UV-MALDI-MS) analysis of highly acidic, thermally labile species such as glycosaminoglycan-derived oligosaccharides is complicated by their poor ionization efficiency and tendency to fragment through the loss of sulfo groups. We have utilized a systematic approach to evaluate the effect of alkali metal counterions on the degree of fragmentation through SO3 loss from a highly sulfated model compound, sucrose octasulfate (SOS). The lithium, sodium, potassium, rubidium, and cesium salts of SOS were analyzed by UV-MALDI-time-of-flight (TOF)MS using an ionic liquid matrix, bis-1,1,3,3-tetramethylguanidinium alpha-cyano-4-hydroxycinnamate. The positive-ion and negative-ion MALDI mass spectra of five alkali metal salts of SOS were compared in terms of the degree of analyte fragmentation through the SO3 loss and the absolute intensity of a molecular ion signal. Experimental results demonstrate that the lithium, sodium, and potassium salts of SOS undergo some degree of fragmentation through the loss of SO3, whereas the fragmentation through the loss of SO3 in the rubidium and cesium salts of SOS is suppressed. A high detection sensitivity associated with the stability of sulfate half-esters was achieved for the cesium salt of SOS using positive-ion detection. Finally, the cesium salt of chondroitin sulfate A disaccharide was successfully analyzed using UV-MALDI-TOFMS.

  13. Mono-, di- and trimethylated homologues of isoprenoid tetraether lipid cores in archaea and environmental samples: mass spectrometric identification and significance.

    PubMed

    Knappy, Chris; Barillà, Daniela; Chong, James; Hodgson, Dominic; Morgan, Hugh; Suleman, Muhammad; Tan, Christine; Yao, Peng; Keely, Brendan

    2015-12-01

    Higher homologues of widely reported C(86) isoprenoid diglycerol tetraether lipid cores, containing 0-6 cyclopentyl rings, have been identified in (hyper)thermophilic archaea, representing up to 21% of total tetraether lipids in the cells. Liquid chromatography-tandem mass spectrometry confirms that the additional carbon atoms in the C(87-88) homologues are located in the etherified chains. Structures identified include dialkyl and monoalkyl ('H-shaped') tetraethers containing C(40-42) or C(81-82) hydrocarbons, respectively, many representing novel compounds. Gas chromatography-mass spectrometric analysis of hydrocarbons released from the lipid cores by ether cleavage suggests that the C(40) chains are biphytanes and the C(41) chains 13-methylbiphytanes. Multiple isomers, having different chain combinations, were recognised among the dialkyl lipids. Methylated tetraethers are produced by Methanothermobacter thermautotrophicus in varying proportions depending on growth conditions, suggesting that methylation may be an adaptive mechanism to regulate cellular function. The detection of methylated lipids in Pyrobaculum sp. AQ1.S2 and Sulfolobus acidocaldarius represents the first reported occurrences in Crenarchaeota. Soils and aquatic sediments from geographically distinct mesotemperate environments that were screened for homologues contained monomethylated tetraethers, with di- and trimethylated structures being detected occasionally. The structural diversity and range of occurrences of the C(87-89) tetraethers highlight their potential as complementary biomarkers for archaea in natural environments.

  14. Mass spectrometric characterization of urinary metabolites of the selective androgen receptor modulator andarine (S-4) for routine doping control purposes.

    PubMed

    Thevis, Mario; Thomas, Andreas; Fusshöller, Gregor; Beuck, Simon; Geyer, Hans; Schänzer, Wilhelm

    2010-08-15

    Selective androgen receptor modulators (SARMs) are potent anabolic agents with tissue-selective properties. Due to their potential misuse in elite sport, the World Anti-Doping Agency (WADA) has prohibited SARMs since 2008, and although no representative drug candidate has yet received full clinical approval, recent findings of SARMs illegally sold via the internet have further supported the need to efficiently test for these compounds in doping controls. In the present communication, the mass spectrometric characterization of urinary metabolites of the SARM Andarine (also referred to as S-4) compared with earlier in vitro and animal studies is reported. Liquid chromatography interfaced to high-resolution/high-accuracy (tandem) mass spectrometry was used to identify phase I and II metabolites, confirming the predicted target analytes for sports drug testing purposes including the glucuronic acid conjugates of the active drug, its monohydroxylated and/or deacetylated product, the hydrolysis product resulting from the removal of the compound's B-ring, as well as the sulfate of the monohydroxylated and the deacetylated phase I metabolite. The obtained data will support future efforts to effectively screen for and confirm the misuse of the non-approved drug candidate Andarine. Copyright (c) 2010 John Wiley & Sons, Ltd.

  15. Simultaneous determination of oxygen, nitrogen and hydrogen in metals by pulse heating and time of flight mass spectrometric method.

    PubMed

    Shen, Xuejing; Wang, Peng; Hu, Shaocheng; Yang, Zhigang; Ma, Hongquan; Gao, Wei; Zhou, Zhen; Wang, Haizhou

    2011-05-30

    The inert gas fusion and infrared absorption and thermal conductivity methods are widely used for quantitative determination of oxygen(O), nitrogen(N) and hydrogen(H) in metals. However, O, N and H cannot be determined simultaneously with this method in most cases and the sensitivity cannot meet the requirement of some new metal materials. Furthermore, there is no equipment or method reported for determination of Argon(Ar) or Helium(He) in metals till now. In this paper, a new method for simultaneous quantitative determination of O, N, H and Ar(or He) in metals has been described in detail, which combined the pulse heating inert gas fusion with time of flight mass spectrometric detection. The whole analyzing process was introduced, including sample retreatment, inert gas fusion, mass spectral line selection, signal acquisition, data processing and calibration. The detection limit, lower quantitative limit and linear range of each element were determined. The accuracy and precision of the new method have also been verified by measurements of several kinds of samples. The results were consistent with that obtained by the traditional method. It has shown that the new method is more sensitive and efficient than the existing method.

  16. Mass spectrometric study of peptides secreted by the skin glands of the brown frog Rana arvalis from the Moscow region.

    PubMed

    Samgina, T Yu; Artemenko, K A; Gorshkov, V A; Ogourtsov, S V; Zubarev, R A; Lebedev, A T

    2009-05-01

    A high-performance liquid chromatography nano-electrospray ionization Fourier transform mass spectrometry (HPLC/nanoESI-FTMS) approach involving recording of collision-activated dissociation (CAD) and electron-capture dissociation (ECD) spectra of an intact sample and two its modifications after performic oxidation and reduction followed by carboxamidomethylation helps to establish peptide profiles in the crude secretion of frog species at mid-throughput level, including de novo sequencing. The proposed derivatization procedures allow increasing of the general sequence coverage in the backbone, providing complementary information and, what is more important, reveal the amino acid sequence in the cystine ring ('rana box'). Thus purely mass spectrometric efficient sequencing becomes possible for longer than usual proteolytic peptides. Seventeen peptides belonging to four known families were identified in the secretion of the European brown frog Rana arvalis inhabiting the Moscow region in Russia. Ranatuerins, considered previously a unique feature of the North American species, as well as a new melittin-related peptide, are worth special mention. The developed approach was previously successfully used for the identification of peptides in the skin secretion of the Caucasian green frog Rana ridibunda. Copyright (c) 2009 John Wiley & Sons, Ltd.

  17. Quantitative determination of total methamphetamine and active metabolites in rat tissue by liquid chromatography with tandem mass spectrometric detection.

    PubMed

    Hendrickson, Howard; Laurenzana, Elizabeth; Owens, S Michael

    2006-11-22

    High-throughput liquid chromatography with tandem mass spectrometric detection (LC-MS/MS) methodology for the determination of methamphetamine (METH), amphetamine (AMP), 4-hydroxymethamphetamine (4-OH-METH), and 4-hydroxyamphetamine (4-OH-AMP) was developed and validated using simple trichloroacetic acid sample treatment. The method was validated in rat serum, brain, and testis. Lower limits-of-quantitation (LOQ) for METH and AMP were 1 ng x mL(-1) using positive ion electrospray tandem mass spectrometry (MS/MS). The accuracy of the method was within 25% of the actual values over a wide range of analyte concentrations. The within-assay precision was better than 12% (coefficient of variation). The method was linear over a wide dynamic range (0.3-1000 ng x mL(-1)). Quantitation was possible in all 3 matrices using only serum standards because of minimal matrix-associated ion effects or the use of an internal standard. Finally, the LC-MS/MS method was used to determine serum, brain, and testis METH and AMP concentrations during a subcutaneous infusion (5.6 mg kg(-1) day(-1)) of METH in rats. Concentrations of 4-OH-AMP and 4-OH-METH were below the LOQ in experimental samples. The bias introduced by using serum calibrators for the determination of METH and AMP concentrations in testis and brain was less than 8% and insignificant relative to the interanimal variability.

  18. Flow-modulated comprehensive two-dimensional gas chromatography with simultaneous flame ionization and quadrupole mass spectrometric detection.

    PubMed

    Krupčík, Ján; Gorovenko, Roman; Spánik, Ivan; Sandra, Pat; Armstrong, Daniel W

    2013-03-08

    Flow-modulated comprehensive two-dimensional gas chromatography with simultaneous monitoring of the separation by flame ionization (GC × GC-FID) and quadrupole mass spectrometric (GC × GC-qMSD) detection was studied for the analysis of gasoline and kerosene samples. The acquisition frequency of the FID was 100 Hz and of the qMSD 18 Hz for the mass range m/z 40-300. The instrumental set-up is such that both one-dimensional (GC-FID and GC-qMSD) and two-dimensional separations using the same working conditions can be performed. Gasoline and kerosene samples were analyzed on the column combination HP-5MS ((1)D)+HP INNOWax ((2)D). Three modulated peaks were obtained for each hydrocarbon present above 0.1% with ca. 300 ms peak width at the base using 6 s modulation times. Modulated peaks in GC × GC-FID were thus characterized by ca. 30 points while those in GC × GC-qMSD method by 6-8 points only. The FID speed is sufficient for reliable quantitative analysis, while the qMSD scan speed is perfectly appropriate for identification purposes. Moreover, in the GC × GC-qMSD method considerably improved quality of uncorrected spectra was obtained, arising from the enhanced separation over one-dimensional GC-MSD analysis. Spectral match qualities of up to 98% were found. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Gas chromatographic-mass spectrometric determination of isotopic enrichment of 6-15NH2 in adenine nucleotides.

    PubMed

    Lewis, S; Yudkoff, M

    1985-03-01

    A gas chromatographic-mass spectrometric method for the determination of isotopic abundance in [6-15NH2]adenine nucleotides is described. The method involves formation of the di-t-butyldimethylsilyl (TBDMS) derivative of adenine following isolation of the nucleotide fraction with solid-phase ion-exchange chromatography and subsequent acid hydrolysis of nucleotides to free base. Mass spectra for both adenine-diTBDMS and [6-15NH2]adenine-diTBDMS were obtained to identify those ions containing the 6-NH2 moiety. The base peak (m/z 306) was formed by loss of C4H9 (57) and constitutes approximately one-third of the total ion current. Using selected ion monitoring of the m/z 306/m/z 307 ratio, levels of isotopic abundance of 1.0-50.0 mol% excess could be measured reproducibly with the injection of 10-20 pmol of the adenine-diTBDMS derivative obtained from isolated rat hepatocytes. Confirmation that measured isotopic abundance was referable to labeling of the 6-15NH2 group was obtained by oxidation of adenine to hypoxanthine and determination of enrichment in the hypoxanthine-diTBDMS derivative. The method was used to study the formation of [6-15NH2]adenine nucleotides during the incubation of isolated rat hepatocytes with [15N]alanine. A level of approximately 6.0 mol% excess was observed at 60 min incubation.

  20. QuEChERS multiresidue method validation and mass spectrometric assessment for the novel anthranilic diamide insecticides chlorantraniliprole and cyantraniliprole.

    PubMed

    Schwarz, Timo; Snow, Timothy A; Santee, Christopher J; Mulligan, Christopher C; Class, Thomas; Wadsley, Michael P; Nanita, Sergio C

    2011-02-09

    The gas-phase dissociation reactions of chlorantraniliprole (Rynaxypyr) and cyantraniliprole (Cyazypyr) have been studied in triple-quadrupole, ion trap, and orbitrap mass spectrometers equipped with electrospray and desorption electrospray ion sources, revealing the formation of odd-electron fragment ions, the structures of which were elucidated. The odd-electron fragments were unusually abundant, and their formation is proposed to occur via a tricyclic intermediate. The applicability of the QuEChERS multiresidue method for the quantitation of chlorantraniliprole and cyantraniliprole was also assessed in this study. Four matrices representative of oily, watery, acidic, and dry crop groups were tested, with a targeted limit of quantitation (LOQ) of 0.01 mg/kg. Average recoveries ranged between 87 and 107%, with relative standard deviations (RSD) of ≤ 8%. Linear calibration functions with correlation coefficients r > 0.99 were obtained. The study provides an expansion of the QuEChERS method to include anthranilic diamides and a mass spectrometric assessment for these two novel agrochemical active ingredients.

  1. Mass Spectrometric N-Glycan Analysis of Haptoglobin from Patient Serum Samples Using a 96-Well Plate Format.

    PubMed

    Zhu, Jianhui; Wu, Jing; Yin, Haidi; Marrero, Jorge; Lubman, David M

    2015-11-06

    Alterations in glycosylation of serum glycoproteins can provide unique and highly specific fingerprints of malignancy. Our previous mass spectrometric study revealed that the bifucosylation level of serum haptoglobin was distinctly increased in hepatocellular carcinoma (HCC) patients versus liver cirrhosis of all three major etiologies. We have thus developed a method for the analysis of large numbers of serum samples based on a 96-well plate platform for the evaluation of fucosylation changes of serum haptoglobin between HCC versus cirrhosis. Haptoglobin was isolated from the serum of individual patient samples based on an HPLC column immobilized with antihaptoglobin antibody via hydrazide immobilization chemistry. Only 10 μL of serum was required for glycan extraction and processing for MALDI-QIT mass spectrometry analysis using the 96-well plate format. The bifucosylation degrees of haptoglobin in individuals were calculated using a quantitative glycomics method. The MS data confirmed that the bifucosylated tetra-anntenary glycan was upregulated in HCC samples of all etiologies. This study provides a parallel method for processing glycan content for haptoglobin and evaluating detailed changes in glycan structures for a potentially large cohort of clinical serum samples.

  2. Advanced Mass Spectrometric Methods for the Rapid and Quantitative Characterization of Proteomes

    DOE PAGES

    Smith, Richard D.

    2002-01-01

    Progress is reviewedmore » towards the development of a global strategy that aims to extend the sensitivity, dynamic range, comprehensiveness and throughput of proteomic measurements based upon the use of high performance separations and mass spectrometry. The approach uses high accuracy mass measurements from Fourier transform ion cyclotron resonance mass spectrometry (FTICR) to validate peptide ‘accurate mass tags’ (AMTs) produced by global protein enzymatic digestions for a specific organism, tissue or cell type from ‘potential mass tags’ tentatively identified using conventional tandem mass spectrometry (MS/MS). This provides the basis for subsequent measurements without the need for MS/ MS. High resolution capillary liquid chromatography separations combined with high sensitivity, and high resolution accurate FTICR measurements are shown to be capable of characterizing peptide mixtures of more than 10 5 components. The strategy has been initially demonstrated using the microorganisms Saccharomyces cerevisiae and Deinococcus radiodurans. Advantages of the approach include the high confidence of protein identification, its broad proteome coverage, high sensitivity, and the capability for stableisotope labeling methods for precise relative protein abundance measurements. Abbreviations : LC, liquid chromatography; FTICR, Fourier transform ion cyclotron resonance; AMT, accurate mass tag; PMT, potential mass tag; MMA, mass measurement accuracy; MS, mass spectrometry; MS/MS, tandem mass spectrometry; ppm, parts per million.« less

  3. A tandem mass spectrometric study of the N-oxides, quinoline N-oxide, carbadox, and olaquindox, carried out at high mass accuracy using electrospray ionization

    NASA Astrophysics Data System (ADS)

    Miao, Xiu-Sheng; March, Raymond E.; Metcalfe, Chris D.

    2003-12-01

    A mass spectrometric study of three N-oxides, quinoline N-oxide, and the synthetic antibiotics carbadox and olaquindox, was carried out with a hybrid quadrupole/time-of-flight (TOF) mass spectrometer coupled with electrospray (ES) and atmospheric pressure chemical ionization (APCI) sources. The full scan mass spectra of the N-oxides obtained with ES are similar to those obtained with APCI, and the characteristic fragment ions corresponding to [M+H-O]+[radical sign] were observed in the full scan mass spectrum of each N-oxide examined. The protonated molecule of each N-oxide was subjected to collision-induced dissociation (CID) and accurate mass measurements were made of each fragment ion so as to determine its elemental composition. Fragment ions generated at enhanced cone voltages upstream of the first mass-resolving element were subjected to CID so as to identify the direct product ion-precursor ion relationship. Plausible structures have been proposed for most of the fragment ions observed. Elimination of OH[radical sign] radicals generated from the N-->O functional group is a characteristic fragmentation pathway of the N-oxides. The expulsion of radicals and small stable molecules is accompanied by formation and subsequent contraction of heterocyclic rings.

  4. Mass Spectrometric and Synchrotron Radiation based techniques for the identification and distribution of painting materials in samples from paints of Josep Maria Sert

    PubMed Central

    2012-01-01

    Background Establishing the distribution of materials in paintings and that of their degradation products by imaging techniques is fundamental to understand the painting technique and can improve our knowledge on the conservation status of the painting. The combined use of chromatographic-mass spectrometric techniques, such as GC/MS or Py/GC/MS, and the chemical mapping of functional groups by imaging SR FTIR in transmission mode on thin sections and SR XRD line scans will be presented as a suitable approach to have a detailed characterisation of the materials in a paint sample, assuring their localisation in the sample build-up. This analytical approach has been used to study samples from Catalan paintings by Josep Maria Sert y Badía (20th century), a muralist achieving international recognition whose canvases adorned international buildings. Results The pigments used by the painter as well as the organic materials used as binders and varnishes could be identified by means of conventional techniques. The distribution of these materials by means of Synchrotron Radiation based techniques allowed to establish the mixtures used by the painter depending on the purpose. Conclusions Results show the suitability of the combined use of SR μFTIR and SR μXRD mapping and conventional techniques to unequivocally identify all the materials present in the sample and their localization in the sample build-up. This kind of approach becomes indispensable to solve the challenge of micro heterogeneous samples. The complementary interpretation of the data obtained with all the different techniques allowed the characterization of both organic and inorganic materials in the samples layer by layer as well as to establish the painting techniques used by Sert in the works-of-art under study. PMID:22616949

  5. Synthesis, purification and mass spectrometric characterisation of a fluorescent Au9@BSA nanocluster and its enzymatic digestion by trypsin

    NASA Astrophysics Data System (ADS)

    Fernández-Iglesias, Nerea; Bettmer, Jörg

    2013-12-01

    Nanoclusters of noble metals like Ag and Au have attracted great attention as they form a missing link between isolated metal atoms and nanoparticles. Their particular properties like luminescence in the visible range and nontoxicity make them attractive for bioimaging and biolabelling purposes, especially with use of proteins as stabilising agents. In this context, this study intends the synthesis of a specific Au nanocluster covered by bovine serum albumin (BSA). It is shown that size-exclusion chromatography is feasible for the purification and isolation of the nanocluster. A mass spectrometric characterisation, preferably by ESI-MS, indicates the presence of an Au9@BSA nanocluster. Enzymatic digestion of the nanocluster with trypsin results in a significant increase of the fluorescence intensity at 650 and 710 nm, whereas complementary MALDI-MS studies are presented for the identification of generated peptides and show a distinctive pattern in comparison to the pure protein. It can be concluded that Au9@BSA might be, in future, an interesting candidate for in vitro studies of protease activities.Nanoclusters of noble metals like Ag and Au have attracted great attention as they form a missing link between isolated metal atoms and nanoparticles. Their particular properties like luminescence in the visible range and nontoxicity make them attractive for bioimaging and biolabelling purposes, especially with use of proteins as stabilising agents. In this context, this study intends the synthesis of a specific Au nanocluster covered by bovine serum albumin (BSA). It is shown that size-exclusion chromatography is feasible for the purification and isolation of the nanocluster. A mass spectrometric characterisation, preferably by ESI-MS, indicates the presence of an Au9@BSA nanocluster. Enzymatic digestion of the nanocluster with trypsin results in a significant increase of the fluorescence intensity at 650 and 710 nm, whereas complementary MALDI-MS studies are presented

  6. Application of mass spectrometric methods to analysis of xenobiotics in biological systems.

    PubMed

    Gross, M L

    1982-01-01

    Tetrachlorodibenzo-para-dioxin (TCDD) has been identified and quantitated at the parts-per-trillion level in three studies involving tissue. The first was an analysis of human milk from mothers in forest areas of the USA where herbicides containing 2,3,7,8-TCDD had been used. The second concerned US veterans of the Vietnam war who may have been exposed to 2,3,7,8-TCDD via contact with the defoliant, Agent Orange. The third was a controlled investigation of the fate of 2,3,7,8-TCDD in the tissue of an exposed rhesus monkey. Mass spectrometry has also been used to develop new methods for trace analysis. High-performance liquid chromatography coupled with gas chromatography/mass spectrometry, negative chemical ionization, mass spectrometry/mass spectrometry and Fourier transform mass spectrometry are described as examples.

  7. Determination of quinolones and fluoroquinolones in fish tissue and seafood by high-performance liquid chromatography with electrospray ionisation tandem mass spectrometric detection.

    PubMed

    Johnston, Lesley; Mackay, Lindsey; Croft, Meg

    2002-12-20

    A reversed-phase high-performance liquid chromatographic method with tandem mass-spectrometric detection was developed and validated for the simultaneous analysis of eight quinolones and fluoroquinolones (oxolinic acid, flumequine, piromidic acid, enrofloxacin, ciprofloxacin, danofloxacin, sarafloxacin and orbifloxacin) in trout tissue, prawns and abalone. The analytes were extracted from homogenised tissue using acetonitrile and the extracts subjected to an automated two-stage solid-phase extraction process involving polymeric reversed-phase and anion-exchange cartridges. Good recoveries were obtained for all analytes and the limit of quantification was 5 microg/kg (10 microg/kg for ciprofloxacin). The limit of detection was 1-3 microg/kg, depending on the analyte and matrix. Confirmation of the identity of a residue was achieved by further tandem mass-spectrometric analysis. A procedure for estimating the uncertainty associated with the measurement is presented.

  8. Differentiation of Aurantii Fructus Immaturus from Poniciri Trifoliatae Fructus Immaturus using flow-injection mass spectrometric (FIMS) metabolic fingerprinting method combined with chemometrics.

    PubMed

    Zhao, Yang; Chang, Yuan-Shiun; Chen, Pei

    2015-03-25

    A flow-injection mass spectrometric metabolic fingerprinting method in combination with chemometrics was used to differentiate Aurantii Fructus Immaturus from its counterfeit Poniciri Trifoliatae Fructus Immaturus. Flow-injection mass spectrometric (FIMS) fingerprints of 9 Aurantii Fructus Immaturus samples and 12 Poniciri Trifoliatae Fructus Immaturus samples were acquired and analyzed using principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA). The authentic herbs were differentiated from their counterfeits easily. Eight characteristic components which were responsible for the differences between the samples were tentatively identified. Furthermore, three out of the eight components, naringin, hesperidin, and neohesperidin, were quantified. The results are useful to help identify the authenticity of Aurantii Fructus Immaturus.

  9. Hydrothermal carbonization of biomass residues: mass spectrometric characterization for ecological effects in the soil-plant system.

    PubMed

    Jandl, Gerald; Eckhardt, Kai-Uwe; Bargmann, Inge; Kücke, Martin; Greef, Jörg-Michael; Knicker, Heike; Leinweber, Peter

    2013-01-01

    Hydrochars, technically manufactured by hydrothermal carbonization (HTC) of biomass residues, are recently tested in high numbers for their suitability as feedstock for bioenergy production, the bioproduct industry, and as long-term carbon storage in soil, but ecological effects in the soil-plant system are not sufficiently known. Therefore, we investigated the influence of different biomass residues and process duration on the molecular composition of hydrochars, and how hydrochar addition to soils affected the germination of spring barley ( L.) seeds. Samples from biomass residues and the corresponding hydrochars were analyzed by pyrolysis-field ionization mass spectrometry (Py-FIMS) and gaseous emissions from the germination experiments with different soil-hydrochar mixtures by gas chromatography/mass spectrometry (GC/MS). The molecular-level characterization of various hydrochars by Py-FIMS clearly showed that the kind of biomass residue influenced the chemical composition of the corresponding hydrochars more strongly than the process duration. In addition to various detected possible toxic substances, two independent mass spectrometric methods (Py-FIMS and GC/MS) indicated long C-chain aliphatic compounds which are typically degraded to the C-unit ethylene that can evoke phytotoxic effects in high concentrations. This showed for the first time possible chemical compounds to explain toxic effects of hydrochars on plant growth. It is concluded that the HTC process did not result in a consistent product with defined chemical composition. Furthermore, possible toxic effects urgently need to be investigated for each individual hydrochar to assess effects on the soil organic matter composition and the soil biota before hydrochar applications as an amendment on agricultural soils.

  10. Quantification and characterization of maize lipid transfer protein, a food allergen, by liquid chromatography with ultraviolet and mass spectrometric detection.

    PubMed

    Kuppannan, Krishna; Albers, David R; Schafer, Barry W; Dielman, Demetrius; Young, Scott A

    2011-01-15

    Maize (Zea mays) is not considered a major allergenic food; however, when food induced allergenic and immunologic reactions have been implicated to maize, lipid transfer proteins (LTPs) have been identified as major allergens. LTP is an extremely stable protein that is resistant to both proteolytic attack and food processing, which permits the allergen to reach the gastrointestinal immune system in an immunogenic and allergenic conformation, allowing sensitization and induction of systemic symptoms. They are considered a complete food allergen in that they are capable of inducing specific IgE as well as eliciting severe symptoms. We have purified and characterized an endogenous ~9 kDa LTP from maize kernels. The maize LTP consists of 93 amino acid residues and has a M(r) of 9046.1 Da, determined by electrospray ionization mass spectrometry. Following accurate identification and characterization of maize LTP, a highly specific and quantitative assay using liquid chromatography with ultraviolet and mass spectrometric detection was developed. The present assay enables determination of LTP over a concentration range from 29 to 1030 μg/g in maize kernel samples. Assay recovery (percent relative error, % RE) was measured at 11 different concentrations ranging from 4 to 147 μg/mL and did not exceed 5.1%. The precision (percent coefficient of variation, % CV) was measured at 3 concentrations on each of 4 days and did not exceed 14.4%. The method was applied to evaluate the levels of LTP in 14 different maize lines. To our knowledge, this represents the first quantitative liquid chromatography-ultraviolet/mass spectrometry (LC-UV/MS) assay for the determination of LTP for the assessment of a food allergen.

  11. Studies of the acidic components of the Colorado Green River formation oil shale-Mass spectrometric identification of the methyl esters of extractable acids.

    NASA Technical Reports Server (NTRS)

    Haug, P.; Schnoes, H. K.; Burlingame, A. L.

    1971-01-01

    Study of solvent extractable acidic constituents of oil shale from the Colorado Green River Formation. Identification of individual components is based on gas chromatographic and mass spectrometric data obtained for their respective methyl esters. Normal acids, isoprenoidal acids, alpha, omega-dicarboxylic acids, mono-alpha-methyl dicarboxylic acids and methyl ketoacids were identified. In addition, the presence of monocyclic, benzoic, phenylalkanoic and naphthyl-carboxylic acids, as well as cycloaromatic acids, is demonstrated by partial identification.

  12. Studies of the acidic components of the Colorado Green River formation oil shale-Mass spectrometric identification of the methyl esters of extractable acids.

    NASA Technical Reports Server (NTRS)

    Haug, P.; Schnoes, H. K.; Burlingame, A. L.

    1971-01-01

    Study of solvent extractable acidic constituents of oil shale from the Colorado Green River Formation. Identification of individual components is based on gas chromatographic and mass spectrometric data obtained for their respective methyl esters. Normal acids, isoprenoidal acids, alpha, omega-dicarboxylic acids, mono-alpha-methyl dicarboxylic acids and methyl ketoacids were identified. In addition, the presence of monocyclic, benzoic, phenylalkanoic and naphthyl-carboxylic acids, as well as cycloaromatic acids, is demonstrated by partial identification.

  13. Discovery of Chromatin-Associated Proteins via Sequence-Specific Capture and Mass Spectrometric Protein Identification in Saccharomyces cerevisiae.

    PubMed

    Kennedy-Darling, Julia; Guillen-Ahlers, Hector; Shortreed, Michael R; Scalf, Mark; Frey, Brian L; Kendziorski, Christina; Olivier, Michael; Gasch, Audrey P; Smith, Lloyd M

    2014-08-01

    DNA-protein interactions play critical roles in the control of genome expression and other fundamental processes. An essential element in understanding how these systems function is to identify their molecular components. We present here a novel strategy, Hybridization Capture of Chromatin Associated Proteins for Proteomics (HyCCAPP), to identify proteins that are interacting with any given region of the genome. This technology identifies and quantifies the proteins that are specifically interacting with a genomic region of interest by sequence-specific hybridization capture of the target region from in vivo cross-linked chromatin, followed by mass spectrometric identification and quantification of associated proteins. We demonstrate the utility of HyCCAPP by identifying proteins associated with three multicopy and one single-copy loci in yeast. In each case, a locus-specific pattern of target-associated proteins was revealed. The binding of previously unknown proteins was confirmed by ChIP in 11 of 17 cases. The identification of many previously known proteins at each locus provides strong support for the ability of HyCCAPP to correctly identify DNA-associated proteins in a sequence-specific manner, while the discovery of previously unknown proteins provides new biological insights into transcriptional and regulatory processes at the target locus.

  14. Determination of phthalate esters in cosmetics by gas chromatography with flame ionization detection and mass spectrometric detection.

    PubMed

    Chen, Huiming; Wang, Chao; Wang, Xing; Hao, Nan; Liu, Juan

    2005-08-01

    A gas chromatography coupled with flame ionization detection (GC-FID) and mass spectrometric detection (MSD) method was developed to determine the six kinds of phthalate esters [dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), benzyl butyl phthalate (BBP), di(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DOP)] in cosmetics (solid, cream and liquid cosmetics). The cosmetics were extracted with methanol by ultrasonic and then separated with high-speed centrifugation. The upper clear layer was dried and filtered through a 0.45 mum pore diameter filter. The filtrate was injected into GC-FID/GC-MS for detection. GC-FID chromatogram was applied for qualitative analysis, external standard method was used for quantitative analysis. Confirmation of phthalate presence was undertaken by GC-EI-MS. The recovery range of all phthalates were between 92.0 and 110.0% with relative standard deviations between 1.95 and 5.92%. The low detection limits of the method were: 0.1 ng for DMP, DEP, DBP and BBP, 0.5 ng for DEHP and DOP. The method had advantages of high precision and sensitivity, simplicity of pretreatment. The method can be used to test the six kinds of phthalate esters in cosmetics.

  15. Gas chromatographic-mass spectrometric determination of brain levels of alpha-cholest-8-en-3beta-ol (lathosterol).

    PubMed

    Luzón-Toro, Berta; Zafra-Gómez, Alberto; Ballesteros, Oscar

    2007-05-01

    A gas chromatographic-mass spectrometric (GC-MS) method is proposed for the detection and quantification of lathosterol in rabbit brain. This compound is one of the most important precursors of the cholesterol synthesis. The interest in brain cholesterol metabolism is growing nowadays since it was described to play an important role in some neurodegenerative disorders such as Alzheimer's disease and Multiple Sclerosis. The analytical methodology proposed involves a liquid-liquid extraction procedure (LLE) followed by a silylation step previous to the GC-MS analysis. The chromatographic separation was performed by using a low bleed HP5-MS fused silica capillary column. A clean up is not necessary when using single-ion monitoring (SIM) mode. The molecular ion appears at 458 m/z; being as well the base peak. Alpha-naphtol was used as an internal standard. The detection limit obtained was 0.09 microg mL(-1). The method was applied to the determination of brain lathosterol levels in rabbits fed with different types of diets (control and atherogenic, supplemented or not with natural polyphenolic antioxidants). The quantification of the compound in samples showed a reduction, after 1 month, of this precursor of cholesterol synthesis in groups fed with antioxidant supplemented diets.

  16. A molecular beam mass spectrometric study of the formation and photolysis of C(lc)lO dimer

    NASA Technical Reports Server (NTRS)

    Greene, Frank T.; Robaugh, David A.

    1992-01-01

    A study of the chlorine oxides present at temperatures and pressures typical of the Antarctic stratosphere was carried out. A series of low temperature flow reactors was constructed and used in conjunction with molecular beam mass spectrometric techniques to identify species and characterize their kinetic behavior at temperatures of -20 to -70 C and pressures of from 30 to 130 Torr. It was found that the gas phase chlorine-oxygen system was quite complex at low temperatures. ClO dimer was identified and found to be thermodynamically very stable under stratospheric conditions. It was also found that any system which contained ClO also contained a larger oxide. The oxide was identified as Cl2O3. A survey of possible higher oxides, which have been postulated as possible chlorine sinks in the stratosphere, was also carried out. The rate of formation of ClO dimer was measured as a function of temperature and pressure. Measurements were made of both the decay of ClO and the formation of the dimer. By comparing these rates it was determined that virtually all of the ClO was converted to the dimer under stratospheric conditions, and that the other ClO reactions were not important under these conditions.

  17. Peptide code-on-a-microplate for protease activity analysis via MALDI-TOF mass spectrometric quantitation.

    PubMed

    Hu, Junjie; Liu, Fei; Ju, Huangxian

    2015-04-21

    A peptide-encoded microplate was proposed for MALDI-TOF mass spectrometric (MS) analysis of protease activity. The peptide codes were designed to contain a coding region and the substrate of protease for enzymatic cleavage, respectively, and an internal standard method was proposed for the MS quantitation of the cleavage products of these peptide codes. Upon the cleavage reaction in the presence of target proteases, the coding regions were released from the microplate, which were directly quantitated by using corresponding peptides with one-amino acid difference as the internal standards. The coding region could be used as the unique "Protease ID" for the identification of corresponding protease, and the amount of the cleavage product was used for protease activity analysis. Using trypsin and chymotrypsin as the model proteases to verify the multiplex protease assay, the designed "Trypsin ID" and "Chymotrypsin ID" occurred at m/z 761.6 and 711.6. The logarithm value of the intensity ratio of "Protease ID" to internal standard was proportional to trypsin and chymotrypsin concentration in a range from 5.0 to 500 and 10 to 500 nM, respectively. The detection limits for trypsin and chymotrypsin were 2.3 and 5.2 nM, respectively. The peptide-encoded microplate showed good selectivity. This proposed method provided a powerful tool for convenient identification and activity analysis of multiplex proteases.

  18. Mass Spectrometric Analysis of TRPM6 and TRPM7 Phosphorylation Reveals Regulatory Mechanisms of the Channel-Kinases

    PubMed Central

    Cai, Na; Bai, Zhiyong; Nanda, Vikas; Runnels, Loren W.

    2017-01-01

    TRPM7 and TRPM6 were the first identified bifunctional channels to contain their own kinase domains, but how these channel-kinases are regulated is poorly understood. Previous studies identified numerous phosphorylation sites on TRPM7, but very little is known about TRPM6 phosphorylation or sites on TRPM7 transphosphorylated by TRPM6. Our mass spectrometric analysis of homomeric and heteromeric TRPM7 and TRPM6 channels identified phosphorylation sites on both proteins, as well as several prominent sites on TRPM7 that are commonly modified through autophosphorylation and transphosphorylation by TRPM6. We conducted a series of amino acid substitution analyses and identified S1777, in TRPM7’s catalytic domain, and S1565, in TRPM7’s exchange domain that mediates kinase dimerization, as potential regulatory sites. The phosphomimetic S1777D substitution disrupted catalytic activity, most likely by causing an electrostatic perturbation at the active site. The S1565D phosphomimetic substitution also inactivated the kinase but did so without interfering with kinase dimerization. Molecular modeling indicates that phosphorylation of S1565 is predicted to structurally affect TRPM7’s functionally conserved N/D loop, which is thought to influence the access of substrate to the active site pocket. We propose that phosphorylation of S1565 within the exchange domain functions as a regulatory switch to control TRPM7 catalytic activity. PMID:28220887

  19. Investigation of isotope dilution mass spectrometric (ID-MS) method to determine niacin in infant formula, breakfast cereals and multivitamins.

    PubMed

    Shin, Hyunju; Kim, Byungjoo; Lee, Joonhee

    2013-06-01

    An isotope dilution LC/mass spectrometric (ID-LC/MS) method was developed as a candidate reference method for the accurate determination of niacin in infant formula, breakfast cereals and multivitamin. After spiking nicotinamide-d(4) as an internal standard, infant formula and breakfast cereal samples were hydrolysed under alkaline condition. Samples were then analysed in SRM mode to detect nicotinic acid and nicotinic acid-d(4) at m/z 124→80 and 127→84, respectively. In the case of multivitamin sample that contains mainly free nicotinamide, LC/MS monitored nicotinamide and nicotinamide-d(4) at their SRM channels of m/z 123→80 and m/z 127→84, respectively, after simple extraction. The repeatability and reproducibility were tested for the validation of the developed ID/LC-MS method. Additionally, the developed analytical method was applied to determine total niacin contents in homogenised infant formula, homogenised multivitamin, and commercially available products including different types of infant formula, breakfast cereals, and multivitamin tablets. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. Discovery of Chromatin-Associated Proteins via Sequence-Specific Capture and Mass Spectrometric Protein Identification in Saccharomyces cerevisiae

    PubMed Central

    2015-01-01

    DNA–protein interactions play critical roles in the control of genome expression and other fundamental processes. An essential element in understanding how these systems function is to identify their molecular components. We present here a novel strategy, Hybridization Capture of Chromatin Associated Proteins for Proteomics (HyCCAPP), to identify proteins that are interacting with any given region of the genome. This technology identifies and quantifies the proteins that are specifically interacting with a genomic region of interest by sequence-specific hybridization capture of the target region from in vivo cross-linked chromatin, followed by mass spectrometric identification and quantification of associated proteins. We demonstrate the utility of HyCCAPP by identifying proteins associated with three multicopy and one single-copy loci in yeast. In each case, a locus-specific pattern of target-associated proteins was revealed. The binding of previously unknown proteins was confirmed by ChIP in 11 of 17 cases. The identification of many previously known proteins at each locus provides strong support for the ability of HyCCAPP to correctly identify DNA-associated proteins in a sequence-specific manner, while the discovery of previously unknown proteins provides new biological insights into transcriptional and regulatory processes at the target locus. PMID:24999558

  1. Mass Spectrometric-Based Selected Reaction Monitoring of Protein Phosphorylation during Symbiotic Signaling in the Model Legume, Medicago truncatula

    PubMed Central

    Maeda, Junko; Barrett-Wilt, Gregory A.; Sussman, Michael R.

    2016-01-01

    Unlike the major cereal crops corn, rice, and wheat, leguminous plants such as soybean and alfalfa can meet their nitrogen requirement via endosymbiotic associations with soil bacteria. The establishment of this symbiosis is a complex process playing out over several weeks and is facilitated by the exchange of chemical signals between these partners from different kingdoms. Several plant components that are involved in this signaling pathway have been identified, but there is still a great deal of uncertainty regarding the early events in symbiotic signaling, i.e., within the first minutes and hours after the rhizobial signals (Nod factors) are perceived at the plant plasma membrane. The presence of several protein kinases in this pathway suggests a mechanism of signal transduction via posttranslational modification of proteins in which phosphate is added to the hydroxyl groups of serine, threonine and tyrosine amino acid side chains. To monitor the phosphorylation dynamics and complement our previous untargeted 'discovery' approach, we report here the results of experiments using a targeted mass spectrometric technique, Selected Reaction Monitoring (SRM) that enables the quantification of phosphorylation targets with great sensitivity and precision. Using this approach, we confirm a rapid change in the level of phosphorylation in 4 phosphosites of at least 4 plant phosphoproteins that have not been previously characterized. This detailed analysis reveals aspects of the symbiotic signaling mechanism in legumes that, in the long term, will inform efforts to engineer this nitrogen-fixing symbiosis in important non-legume crops such as rice, wheat and corn. PMID:27203723

  2. Molecular cloning, mass spectrometric identification, and nutritional evaluation of 10 coixins in adlay ( Coix lachryma-jobi L.).

    PubMed

    Lin, Li-Jen; Hsiao, Eric S L; Tseng, Hsen-Shong; Chung, Mei-Chu; Chua, Anna C N; Kuo, Ming-En; Tzen, Jason T C

    2009-11-25

    Adlay (Coix lachryma-jobi L. var. ma-yuen Stapf) is regarded as a nutritive food source as well as herbal medicine. The food nutrition is a consequence of its high protein content and superior amino acid composition. From ca. 200 expressed sequence tag (EST) sequences in maturing adlay grains, clones encoding precursor polypeptides of 10 seed storage proteins in the prolamin family, including 8 alpha-coixin isoforms, 1 delta-coixin, and 1 gamma-coixin, were identified. Full-length cDNA fragments encoding these 10 coixins were obtained by PCR cloning. Mass spectrometric analyses confirmed the presence of these 10 coixins in the extract of adlay grain. Calculated amino acid compositions indicate that all 10 coixins are rich in glutamine (>20% in alpha-coixin isoforms, 13.3% in delta-coixin, and 31.2% in gamma-coixin). The 8 alpha-coixin isoforms are low in methionine, cysteine, and lysine (on average, 0.8, 0.6, and 0.1%, respectively). However, the delta-coixin is a sulfur-rich protein (18.2% methionine and 9.1% cysteine), and the gamma-coixin is a nutritive protein composed of 2.0% methionine, 6.6% cysteine, 2.6% lysine, and 8.9% histidine. The company of delta-coixin and gamma-coixin with alpha-coixin isoforms enhances the nutritional value of alday grain for human consumption.

  3. Mass spectrometric gas composition measurements associated with jet interaction tests in a high-enthalpy wind tunnel

    NASA Technical Reports Server (NTRS)

    Lewis, B. W.; Brown, K. G.; Wood, G. M., Jr.; Puster, R. L.; Paulin, P. A.; Fishel, C. E.; Ellerbe, D. A.

    1986-01-01

    Knowledge of test gas composition is important in wind-tunnel experiments measuring aerothermodynamic interactions. This paper describes measurements made by sampling the top of the test section during runs of the Langley 7-Inch High-Temperature Tunnel. The tests were conducted to determine the mixing of gas injected from a flat-plate model into a combustion-heated hypervelocity test stream and to monitor the CO2 produced in the combustion. The Mass Spectrometric (MS) measurements yield the mole fraction of N2 or He and CO2 reaching the sample inlets. The data obtained for several tunnel run conditions are related to the pressures measured in the tunnel test section and at the MS ionizer inlet. The apparent distributions of injected gas species and tunnel gas (CO2) are discussed relative to the sampling techniques. The measurements provided significant real-time data for the distribution of injected gases in the test section. The jet N2 diffused readily from the test stream, but the jet He was mostly entrained. The amounts of CO2 and Ar diffusing upward in the test section for several run conditions indicated the variability of the combustion-gas test-stream composition.

  4. Mass Spectrometric Analysis of TRPM6 and TRPM7 Phosphorylation Reveals Regulatory Mechanisms of the Channel-Kinases.

    PubMed

    Cai, Na; Bai, Zhiyong; Nanda, Vikas; Runnels, Loren W

    2017-02-21

    TRPM7 and TRPM6 were the first identified bifunctional channels to contain their own kinase domains, but how these channel-kinases are regulated is poorly understood. Previous studies identified numerous phosphorylation sites on TRPM7, but very little is known about TRPM6 phosphorylation or sites on TRPM7 transphosphorylated by TRPM6. Our mass spectrometric analysis of homomeric and heteromeric TRPM7 and TRPM6 channels identified phosphorylation sites on both proteins, as well as several prominent sites on TRPM7 that are commonly modified through autophosphorylation and transphosphorylation by TRPM6. We conducted a series of amino acid substitution analyses and identified S1777, in TRPM7's catalytic domain, and S1565, in TRPM7's exchange domain that mediates kinase dimerization, as potential regulatory sites. The phosphomimetic S1777D substitution disrupted catalytic activity, most likely by causing an electrostatic perturbation at the active site. The S1565D phosphomimetic substitution also inactivated the kinase but did so without interfering with kinase dimerization. Molecular modeling indicates that phosphorylation of S1565 is predicted to structurally affect TRPM7's functionally conserved N/D loop, which is thought to influence the access of substrate to the active site pocket. We propose that phosphorylation of S1565 within the exchange domain functions as a regulatory switch to control TRPM7 catalytic activity.

  5. A liquid chromatography-mass spectrometric method for the determination of oak moss allergens atranol and chloroatranol in perfumes.

    PubMed

    Bossi, Rossana; Rastogi, Suresh C; Bernard, Guillaume; Gimenez-Arnau, Elena; Johansen, Jeanne D; Lepoittevin, Jean-Pierre; Menné, Torkil

    2004-05-01

    This paper describes a validated liquid chromatographic-tandem mass spectrometric method for quantitative analysis of the potential oak moss allergens atranol and chloroatranol in perfumes and similar products. The method employs LC-MS-MS with electrospray ionization (ESI) in negative mode. The compounds are analysed by selective reaction monitoring (SRM) of 2 or 3 ions for each compound in order to obtain high selectivity and sensitivity. The method has been validated for the following parameters: linearity; repeatability; recovery; limit of detection; and limit of quantification. The limits of detection, 5.0 ng/mL and 2.4 ng/mL, respectively, for atranol and chloroatranol, achieved by this method allowed identification of these compounds at concentrations below those causing allergic skin reactions in oak-moss-sensitive patients. The recovery of chloratranol from spiked perfumes was 96+/-4%. Low recoveries (49+/-5%) were observed for atranol in spiked perfumes, indicating ion suppression caused by matrix components. The method has been applied to the analysis of 10 randomly selected perfumes and similar products.

  6. Gas chromatography-high-resolution mass spectrometric method for determination of methamphetamine and its major metabolite amphetamine in human hair.

    PubMed

    Kim, Jin Young; Suh, Sung Ill; In, Moon Kyo; Chung, Bong Chul

    2005-01-01

    Gas chromatography-high-resolution mass spectrometric (GC-HRMS) method is presented for the qualitative and quantitative analysis of methamphetamine (MA) and its major metabolite, amphetamine (AMP), in human hair. The method procedure involves decontamination of hair with distilled water and acetone, acidic hydrolysis and extraction in the presence of the internal standard, and GC-HRMS selective ion monitoring (SIM) analysis. The limits of detection (LOD) were 9 pg/mg for MA and 21 pg/mg for AMP using a 30-mg hair sample, and the SIM responses were linear with coefficients of correlation ranged from 0.9998 to 0.9999. The recoveries were found to be 91.1-92.3%. By using HRMS (resolution of 5000), detection sensitivity is improved because of the elimination of the biological background, and the LODs for MA and AMP were 2.4-4.4 times lower than those of low-resolution MS. The GC-HRMS method was successfully applied to the analysis of cosmetically treated hair, which is difficult to analyze with the conventional method.

  7. Abortion after deliberate Arthrotec® addition to food. Mass spectrometric detection of diclofenac, misoprostol acid, and their urinary metabolites.

    PubMed

    Watzer, Bernhard; Lusthof, Klaas J; Schweer, Horst

    2015-07-01

    Arthrotec(®) (AT) is a combination of diclofenac, a nonsteroidal anti-inflammatory drug (NSAID), and misoprostol (MP), a synthetic analogue of prostaglandin E1 (PGE1). MP is a lipophilic methyl ester prodrug. It is readily metabolized to the biologically active misoprostol acid (MPA). During the last few years, medical studies exhibited MP to be an excellent abortive. In this paper, we describe a rare criminal case of MP abortion, initiated by the expectant father. After the abortion, samples of vomit and urine were collected. Systemic exposure to MP is difficult to prove, because both MP and the active metabolite MPA are hardly excreted in urine. Therefore, in addition to routine toxicological analysis, we used slightly modified, well-established liquid and gas chromatographic/tandem mass spectrometric (LC/MS/MS and GC/MS/MS) methods, for the direct and the indirect detection of MPA and its metabolites. In this case, we were able to demonstrate the presence of the major MP metabolites 2,3-dinor-MPA and 2,3,4,5-tetranor-MPA in the urine of the victim. We also detected paracetamol, 3-methoxyparacetamol and diclofenac-glucuronide in the urine. In the vomit of the victim, we detected diclofenac and MPA. These results, combined with the criminal investigations, showed that the accused had mixed MP into the food of his pregnant girlfriend. Finally, these investigations contributed to a confession of the accused.

  8. iTRAQ-based profiling of grape berry exocarp proteins during ripening using a parallel mass spectrometric method.

    PubMed

    Martínez-Esteso, Maria José; Casado-Vela, Juan; Sellés-Marchart, Susana; Elortza, Felix; Pedreño, Maria Angeles; Bru-Martínez, Roque

    2011-03-01

    The 4-plex iTRAQ platform was utilized to analyze the protein profiles in four stages of grapevine berry skin ripening, from pre-veraison to fully ripening. Mass spectrometric data were acquired from three replicated analyses using a parallel acquisition method in an Orbitrap instrument by combining collision-induced dissociation (CID) and higher energy collision-induced dissociation (HCD) peptide ion fragmentations. As a result, the number of spectra suitable for peptide identification (either from CID or HCD) increased 5-fold in relation to those suitable for quantification (from HCD). Spectra were searched against an NCBInr protein database subset containing all the Vitis sequences, including those derived from whole genome sequencing. In general, 695 unique proteins were identified with more than one single peptide, and 513 of them were quantified. The sequence annotation and GO term enrichment analysis assisted by the automatic annotation tool Blast2GO permitted a pathway analysis which resulted in finding that biological processes and metabolic pathways de-regulated throughout ripening. A detailed analysis of the function-related proteins profiles helped discover a set of proteins of known Vitis gene origin as the potential candidates to play key roles in grapevine berry quality, growth regulation and disease resistance.

  9. Development and validation of a liquid chromatographic-tandem mass spectrometric method for determination of eleven coccidiostats in milk.

    PubMed

    Nász, Szilárd; Debreczeni, Lajos; Rikker, Tamás; Eke, Zsuzsanna

    2012-07-15

    A reversed phase liquid chromatographic-tandem mass spectrometric method with simple solvent extraction and purification by solid phase extraction (SPE) has been developed for the determination of coccidiostats in milk. For sample preparation matrix solid phase dispersion, extraction by organic solvent and SPE with different cartridges were also tested. The compounds determined include lasalocid, narasin, salinomycin, monensin, semduramicin, maduramicin, robenidine, decoquinate, halofuginone, nicarbazin and diclazuril. Main steps of the method are addition of acetonitrile to the milk samples, centrifugation, removal of matrix by SPE, concentration by evaporation and LC-MS-MS determination. During a 15 min time segmented chromatographic run compounds are ionised either positively or negatively. Calculated recoveries range between 77.1% and 118.2%. Maximum levels are in the range of 1-20 μg/kg. The developed method was validated in line with the requirements of Commission Decision 2002/657/EC (2002). It is applicable for control of coccidiostat residues in milk as indicated in Regulation 124/2009/EC (2009). Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Combining Mass Spectrometric Metabolic Profiling with Genomic Analysis: A Powerful Approach for Discovering Natural Products from Cyanobacteria.

    PubMed

    Kleigrewe, Karin; Almaliti, Jehad; Tian, Isaac Yuheng; Kinnel, Robin B; Korobeynikov, Anton; Monroe, Emily A; Duggan, Brendan M; Di Marzo, Vincenzo; Sherman, David H; Dorrestein, Pieter C; Gerwick, Lena; Gerwick, William H

    2015-07-24

    An innovative approach was developed for the discovery of new natural products by combining mass spectrometric metabolic profiling with genomic analysis and resulted in the discovery of the columbamides, a new class of di- and trichlorinated acyl amides with cannabinomimetic activity. Three species of cultured marine cyanobacteria, Moorea producens 3L, Moorea producens JHB, and Moorea bouillonii PNG, were subjected to genome sequencing and analysis for their recognizable biosynthetic pathways, and this information was then compared with their respective metabolomes as detected by MS profiling. By genome analysis, a presumed regulatory domain was identified upstream of several previously described biosynthetic gene clusters in two of these cyanobacteria, M. producens 3L and M. producens JHB. A similar regulatory domain was identified in the M. bouillonii PNG genome, and a corresponding downstream biosynthetic gene cluster was located and carefully analyzed. Subsequently, MS-based molecular networking identified a series of candidate products, and these were isolated and their structures rigorously established. On the basis of their distinctive acyl amide structure, the most prevalent metabolite was evaluated for cannabinomimetic properties and found to be moderate affinity ligands for CB1.

  11. Improved mass spectrometric analysis of membrane proteins based on rapid and versatile sample preparation on nanodiamond particles.

    PubMed

    Pham, Minh D; Yu, Steve S-F; Han, Chau-Chung; Chan, Sunney I

    2013-07-16

    We have developed a novel streamlined sample preparation procedure for mass spectrometric (MS) analysis of membrane proteins using surface-oxidized nanodiamond particles. The platform consists of solid-phase extraction and elution of the membrane proteins on nanodiamonds, concentrating the membrane proteins on the nanodiamonds and separating out detergents, chaotropic agents, and salts, and other impurities that are often present at high concentrations in solubilized membrane preparations. In this manner, membrane-protein extracts are transformed into MS-ready samples in minutes. The protocol is not only fast, but also widely adaptable and highly effective for preparing generic membrane protein samples for both MALDI-MS studies of membrane-protein complexes and shotgun membrane proteomics studies. As proof of concept, we have demonstrated substantial improvements in the MALDI-MS analysis of the particulate methane monooxygenase (pMMO) complex, a three-subunit transmembrane protein solubilized in various detergent buffers. Enzymatic digestions of membrane proteins are also greatly facilitated since the proteins extracted on to the nanodiamonds are exposed on the surface of the nanoparticles rather than in SDS gels or in detergent solutions. We illustrate the effectiveness of nanodiamonds for SDS removal in the preparation of membrane proteins for MS analysis on the proteome level by examining the quality of the tryptic peptides prepared by on-surface nanodiamond digestion of an E. coli membrane fraction for shotgun proteomics.

  12. Comprehensive ultra-performance liquid chromatographic separation and mass spectrometric analysis of eicosanoid metabolites in human samples.

    PubMed

    Wang, Yan; Armando, Aaron M; Quehenberger, Oswald; Yan, Chao; Dennis, Edward A

    2014-09-12

    Over the past decade, the number of known eicosanoids has expanded immensely and we have now developed an ultra-performance liquid chromatography-electrospray ionization triple quadrupole mass spectrometric (UPLC-QTRAP/MS/MS) method to monitor and quantify numerous eicosanoids. The UPLC-QTRAP/MS/MS approach utilizes scheduled multiple reaction monitoring (MRM) to optimize sensitivity, number of metabolites that can be analyzed and the time requirement of the analysis. A total of 184 eicosanoids including 26 deuterated internal standards can be separated and monitored in a single 5min UPLC run. To demonstrate a practical application, human plasma samples were analyzed following solid-phase extraction (SPE) and the recovery rate and matrix effects were determined for the 26 deuterated internal standards added to the plasma. The method was validated and shown to be sensitive with the limit of quantitation at pg levels for most compounds, accurate with recovery rates of 70-120%, and precise with a CV<30 for all compounds. Also, the method showed a linear response over a range spanning several orders of magnitude. In a QC human plasma sample, we identified and rigorously quantified over 120 eicosanoids.

  13. Selective isolation of hydrophobin SC3 by solid-phase extraction with polytetrafluoroethylene microparticles and subsequent mass spectrometric analysis.

    PubMed

    Kupčík, Rudolf; Zelená, Miroslava; Řehulka, Pavel; Bílková, Zuzana; Česlová, Lenka

    2016-02-01

    Hydrophobins are small proteins that play a role in a number of processes during the filamentous fungi growth and development. These proteins are characterized by the self-assembly of their molecules into an amphipathic membrane at hydrophilic-hydrophobic interfaces. Isolation and purification of hydrophobins generally present a challenge in their analysis. Hydrophobin SC3 from Schizophyllum commune was selected as a representative of class I hydrophobins in this work. A novel procedure for selective and effective isolation of hydrophobin SC3 based on solid-phase extraction with polytetrafluoroethylene microparticles loaded in a small self-made microcolumn is reported. The tailored binding of hydrophobins to polytetrafluoroethylene followed by harsh elution conditions resulted in a highly specific isolation of hydrophobin SC3 from the model mixture of ten proteins. The presented isolation protocol can have a positive impact on the analysis and utilization of these proteins including all class I hydrophobins. Hydrophobin SC3 was further subjected to reduction of its highly stable disulfide bonds and to chymotryptic digestion followed by mass spectrometric analysis. The isolation and digestion protocols presented in this work make the analysis of these highly hydrophobic and compact proteins possible.

  14. Electrospray ionization Fourier transform mass spectrometric analysis of intact bikunin glycosaminoglycan from normal human plasma.

    PubMed

    Laremore, Tatiana N; Leach, Franklin E; Amster, I Jonathan; Linhardt, Robert J

    2011-08-15

    A mixture of glycosaminoglycan (GAG) chains from a plasma proteoglycan bikunin was fractionated using native, continuous-elution polyacrylamide gel electrophoresis, and the resulting fractions were analyzed by electrospray ionization Fourier transform mass spectrometry (ESI FTMS). Molecular mass analysis of the intact GAG afforded information about the length and composition of GAG chains in the mixture. Ambiguity in the interpretation of the intact GAG mass spectra was eliminated by conducting an additional experiment in which the GAG chains of known molecular mass were treated with a GAG-degrading enzyme, chondroitinase ABC, and the digestion products were analyzed by ESI FTMS. The plasma bikunin GAG chains consisted predominantly of odd number of saccharides, although few chains consisting of even number of saccharides were also detected. Majority of the analyzed chains were tetrasulfated or pentasulfated and comprised by 29 to 41 monosaccharides.

  15. Production of deuterated lutein by Chlorella protothecoides and its detection by mass spectrometric methods.

    PubMed

    Bhosale, Prakash; Serban, Bogdan; Bernstein, Paul S

    2006-09-01

    Chlorella protothecoides, a lutein-producing microalga, was grown aerobically in a mineral medium prepared with 70% (v/v) deuterated water. HPLC/atmospheric pressure chemical ionization-mass spectrometry (HPLC/APCI-MS) analysis revealed approximately 58% replacement of hydrogen by deuterium atoms as indicated by the molecular mass cluster at around m/z 599. The rapidly growing microalga had much higher levels (58%) of deuterium substitution relative to previously reported (9-15%) natural sources of lutein.

  16. Mass Spectrometric Measurements of the Concentrations of Gaseous Species in Reactive Flow Systems.

    DTIC Science & Technology

    1982-04-01

    concentrations of gaseous species in the ramjet combustor flow field under simulated combustion conditions. The goal of this effort was to study fuel-air... field patterns, all of which affect the operation of the mass spectrometer, a continously operating built-in calibration system must be utilized in order...sampling probe was first allowed to traverse the combustor flow field , into which only pure air had been injected. The mass spectrometer system was

  17. Mass Spectrometric Determination of Chemical Warfare Agents in Indoor Sample Media Typically Collected During Forensic Investigations

    DTIC Science & Technology

    2005-10-01

    la lutte contre le terrorisme. On s’attend A ce que continue la mise au point et l’application de la spectrom~trie de masse en tandem aux...terrorist use of weapons of mass destruction was the establishment of the Chemical, biological , radiological and nuclear Research and Technology Initiative...CRTI). This research-oriented organization originally formed three clusters to deal with the challenges associated with each of chemical, biological

  18. Role of the sample supports in the LDI mass spectrometric studies of silver clusters

    NASA Astrophysics Data System (ADS)

    Smolira, Anna

    2012-12-01

    One of the basic parameters of the LDI TOF MS (laser desorption ionization time of flight mass spectrometry) method is its sensitivity. It depends on many factors such as the proper sample preparation. Within the sample preparation various steps are taken to achieve the greatest sensitivity of the LDI method. One of them is the application of so-called sample supports on the stainless steel sample holder surface, on which the sample is loaded. The aim of this study was to examine the influence of sample supports selected by the author on the outcome of the experiment. In this respect, silver benzoate was studied. The apparatus used was a linear time of flight mass spectrometer and the method of ionization was LD (laser desorption). Mass spectra obtained for the sample support materials (glass, mica, floppy disc foil, copper, aluminium foil) were compared to those obtained with the stainless steel. All of these were recorded under identical experimental conditions. Mass spectra were characterized in terms of mass peaks registered. It was noted that the processes of silver clustering for each sample support and the stainless steel ran with different intensity. The largest registered ion cluster Agn was the biggest for floppy disc foil (n = 92), the smallest for copper (n = 59). The FWHM parameter in the case of Ag+ and Ag- ion mass peaks was the smallest for stainless steel. Metallic sample supports (copper, aluminum foil) appeared to be advantageous for the studies of negative ion mass spectra - negative ion current corresponding to particular ion mass peaks was then more intensive than positive ion current. The mica was the exception.

  19. Liquid chromatography-Fourier transform ion cyclotron resonance mass spectrometric characterization of protein kinase C phosphorylation.

    PubMed

    Chalmers, Michael J; Quinn, John P; Blakney, Greg T; Emmett, Mark R; Mischak, Harold; Gaskell, Simon J; Marshall, Alan G

    2003-01-01

    A vented column, capillary liquid chromatography (LC) microelectrospray ionization (ESI) Fourier transform ion cyclotron resonance (FT-ICR (9.4 T)) mass spectrometry (MS) approach to phosphopeptide identification is described. A dual-ESI source capable of rapid (approximately 200 ms) switching between two independently controlled ESI emitters was constructed. The dual-ESI source, combined with external ion accumulation in a linear octopole ion trap, allowed for internal calibration of every mass spectrum during LC. LC ESI FT-ICR positive-ion MS of protein kinase C (PKC) revealed four previously unidentified phosphorylated peptides (one within PKC(alpha), one within PKC(delta), and two within PKC(zeta)). Internal calibration improved the mass accuracy for LC MS spectra from an absolute mean (47 peptide ions) of 11.5 ppm to 1.5 ppm. Five additional (out of eight known) activating sites of PKC phosphorylation, not detected in positive-ion experiments, were observed by subsequent negative-ion direct infusion nanoelectrospray. Extension of the method to enable infrared multiphoton dissociation of all ions in the ICR cell prior to every other mass measurement revealed the diagnostic neutral loss of H3PO4 from phosphorylated peptide ions. The combination of accurate-mass MS and MS/MS offers a powerful new tool for identifying the presence and site(s) of phosphorylation in peptides, without the need for additional wet chemical derivatization.

  20. Mass spectrometric signatures of the blood plasma metabolome for disease diagnostics.

    PubMed

    Lokhov, Petr G; Balashova, Elena E; Voskresenskaya, Anna A; Trifonova, Oxana P; Maslov, Dmitry L; Archakov, Alexander I

    2016-01-01

    In metabolomics, a large number of small molecules can be detected in a single run. However, metabolomic data do not include the absolute concentrations of each metabolite. Generally, mass spectrometry analyses provide metabolite concentrations that are derived from mass peak intensities, and the peak intensities are strictly dependent on the type of mass spectrometer used, as well as the technical characteristics, options and protocols applied. To convert mass peak intensities to actual concentrations, calibration curves have to be generated for each metabolite, and this represents a significant challenge depending on the number of metabolites that are detected and involved in metabolome-based diagnostics. To overcome this limitation, and to facilitate the development of diagnostic tests based on metabolomics, mass peak intensities may be expressed in quintiles. The present study demonstrates the advantage of this approach. The examples of diagnostic signatures, which were designed in accordance to this approach, are provided for lung and prostate cancer (leading causes of mortality due to cancer in developed countries) and impaired glucose tolerance (which precedes type 2 diabetes, the most common endocrinology disease worldwide).

  1. Development of mass spectrometric techniques applicable to the search for organic matter in the lunar crust

    NASA Technical Reports Server (NTRS)

    Biemann, K.

    1973-01-01

    Data processing techniques were developed to measure with high precision and sensitivity the line spectra produced by a high resolution mass spectrometer. The most important aspect of this phase was the interfacing of a modified precision microphotometer-comparator with a computer and the improvement of existing software to serve the special needs of the investigation of lunar samples. In addition, a gas-chromatograph mass spectrometer system was interfaced with the same computer to allow continuous recording of mass spectra on a gas chromatographic effluent and efficient evaluation of the resulting data. These techniques were then used to detect and identify organic compounds present in the samples returned by the Apollo 11 and 12 missions.

  2. Development of an effusive inlet for mass spectrometric gas analysis of hypersonic boundary layer

    NASA Technical Reports Server (NTRS)

    Brown, Kenneth G.; Fishel, Charles E.; Brown, David R.; Lewis, Beverley W.; Wood, George M., Jr.

    1987-01-01

    The use of a microchannel plate (MCP) as a mass spectrometer inlet device to allow nonintrusive sampling of flight vehicle boundary layers is investigated. Two possible configurations for mounting the inlet are studied: (1) flow coaxial with the channels; and (2) flow perpendicular to the channel axis. The test gases are pure Kr; pure Ne; and a mixture of 10 pct Kr, 10 pct Ne, and 80 pct N2. The pressure ranges studied vary from 500 to 10 microns. A mass discrimination at the quadrupole mass spectrometer is observed, indicating an enrichment in the heavier gas. Possible explanations for this enrichment are discussed. It is shown that an MCP is capable of acting as a nonintrusive sampling device. Further work that will enable quantitative determination of the species at the surface is discussed.

  3. Fingerprinting Breast Cancer vs. Normal Mammary Cells by Mass Spectrometric Analysis of Volatiles

    PubMed Central

    He, Jingjing; Sinues, Pablo Martinez-Lozano; Hollmén, Maija; Li, Xue; Detmar, Michael; Zenobi, Renato

    2014-01-01

    There is increasing interest in the development of noninvasive diagnostic methods for early cancer detection, to improve the survival rate and quality of life of cancer patients. Identification of volatile metabolic compounds may provide an approach for noninvasive early diagnosis of malignant diseases. Here we analyzed the volatile metabolic signature of human breast cancer cell lines versus normal human mammary cells. Volatile compounds in the headspace of conditioned culture medium were directly fingerprinted by secondary electrospray ionization-mass spectrometry. The mass spectra were subsequently treated statistically to identify discriminating features between normal vs. cancerous cell types. We were able to classify different samples by using feature selection followed by principal component analysis (PCA). Additionally, high-resolution mass spectrometry allowed us to propose their chemical structures for some of the most discriminating molecules. We conclude that cancerous cells can release a characteristic odor whose constituents may be used as disease markers. PMID:24903350

  4. Fingerprinting Breast Cancer vs. Normal Mammary Cells by Mass Spectrometric Analysis of Volatiles

    NASA Astrophysics Data System (ADS)

    He, Jingjing; Sinues, Pablo Martinez-Lozano; Hollmén, Maija; Li, Xue; Detmar, Michael; Zenobi, Renato

    2014-06-01

    There is increasing interest in the development of noninvasive diagnostic methods for early cancer detection, to improve the survival rate and quality of life of cancer patients. Identification of volatile metabolic compounds may provide an approach for noninvasive early diagnosis of malignant diseases. Here we analyzed the volatile metabolic signature of human breast cancer cell lines versus normal human mammary cells. Volatile compounds in the headspace of conditioned culture medium were directly fingerprinted by secondary electrospray ionization-mass spectrometry. The mass spectra were subsequently treated statistically to identify discriminating features between normal vs. cancerous cell types. We were able to classify different samples by using feature selection followed by principal component analysis (PCA). Additionally, high-resolution mass spectrometry allowed us to propose their chemical structures for some of the most discriminating molecules. We conclude that cancerous cells can release a characteristic odor whose constituents may be used as disease markers.

  5. Vacuum-Ultraviolet Photoionization and Mass Spectrometric Characterization of Lignin Monomers Coniferyl and Sinapyl Alcohols

    SciTech Connect

    Takahashi, Lynelle K.; Zhou, Jia; Kostko, Oleg; Golan, Amir; Leone, Stephen R.; Ahmed, Musahid

    2011-02-09

    The fragmentation mechanisms of monolignols under various energetic processes are studied with jet-cooled thermal desorption molecular beam (TDMB) mass spectrometry (MS), 25 keV Bi3+ secondary ion MS (SIMS), synchrotron vacuum-ultraviolet secondary neutral MS (VUV-SNMS) and theoretical methods. Experimental and calculated appearance energies of fragments observed in TDMB MS indicate that the coniferyl alcohol photoionization mass spectra contain the molecular parent and several dissociative photoionization products. Similar results obtained for sinapyl alcohol are also discussed briefly. Ionization energies of 7.60 eV ? 0.05 eV for coniferyl alcohol and<7.4 eV for both sinapyl and dihydrosinapyl alcohols are determined. The positive ion SIMS spectrum of coniferyl alcohol shares few characteristic peaks (m/z = 137 and 151) with the TDMB mass spectra, shows extensive fragmentation, and does not exhibit clear molecular parent signals. VUV-SNMS spectra, on the other hand, are dominated by the parent ion and main fragments also present in the TDMB spectra. Molecular fragmentation in VUV-SNMS spectra can be reduced by increasing the extraction delay time. Some features resembling the SIMS spectra are also observed in the desorbed neutral products. The monolignol VUV-SNMS peaks shared with the TDMB mass spectra suggest that dissociative photoionization of ion-sputtered neutral molecules predominate in the VUV-SNMS mass spectra, despite the extra internal energy imparted in the initial ion impact. The potential applications of these results to imaging mass spectrometry of bio-molecules are discussed.

  6. Liquid chromatography with electrospray ionisation mass spectrometric detection of phenolic compounds from Olea europaea.

    PubMed

    Ryan, D; Robards, K; Prenzler, P; Jardine, D; Herlt, T; Antolovich, M

    1999-09-10

    The results demonstrate the potential of electrospray ionisation mass spectrometry for the specific detection of phenolic species in olives. Phenolic compounds were detected with greater sensitivity in the negative ion mode, but results from positive and negative ion modes were complementary with the positive ion mode showing structurally significant fragments. This is demonstrated by the identification of oleuropein and isomers of verbascoside. The structure of the latter were confirmed by retention, mass spectral and nuclear magnetic resonance data. These isomers have not previously been reported in olive.

  7. Mass spectrometric identification and quantification of 5-methoxytryptophol in quail retina

    SciTech Connect

    Tsang, C.W.; Chan, S.F.; Lee, P.P.; Pang, S.F. )

    1989-12-29

    The occurrence of 5-methoxytryptophol (5-MTL) in the quail retina was investigated by capillary column gas chromatography/mass spectrometry/selected ion monitoring using a deuterated internal standard. Based on ion intensity ratios in the mass spectra of pentafluoropropionyl and heptafluorobutyryl derivatives of 5-MTL and deuterated 5-MTL, 5-MTL was unequivocally identified in the quail retina. Similar to the circadian rhythm of retinal melatonin, retinal 5-MTL also exhibited a diurnal variation with high levels at mid-dark. However, no significant correlation between the diurnal levels of 5-MTL and melatonin was observed in the quail retina at mid-light or mid-dark.

  8. Electrospray ionization mass spectrometric studies of some imidazole amidoximes and nitrolic acids and their esters.

    PubMed

    Oresmaa, Larisa; Aulaskari, Paula; Vainiotalo, Pirjo

    2006-01-01

    The fragmentations of the [M+H]+ ions of imidazole amidoximes, and nitrolic acids and their esters, were studied by collision-induced dissociation experiments and by determining the accurate masses of the product ions on an electrospray ionization Fourier transform ion cyclotron resonance mass spectrometer. The fragmentation pathways of the amidoximes varied with the substituent in the imidazole ring at position 1N, allowing two regioisomers to be distinguished. Nitrolic acids decompose in solution to nitrile oxides, and the studied nitrolic acid behaved in the same way in the gas phase. The esters decompose similarly to their parent compounds.

  9. Focused analyte spray emission apparatus and process for mass spectrometric analysis

    DOEpatents

    Roach, Patrick J [Kennewick, WA; Laskin, Julia [Richland, WA; Laskin, Alexander [Richland, WA

    2012-01-17

    An apparatus and process are disclosed that deliver an analyte deposited on a substrate to a mass spectrometer that provides for trace analysis of complex organic analytes. Analytes are probed using a small droplet of solvent that is formed at the junction between two capillaries. A supply capillary maintains the droplet of solvent on the substrate; a collection capillary collects analyte desorbed from the surface and emits analyte ions as a focused spray to the inlet of a mass spectrometer for analysis. The invention enables efficient separation of desorption and ionization events, providing enhanced control over transport and ionization of the analyte.

  10. A comparative mass spectrometric study of fatty acids and metals in some seed extracts.

    PubMed

    Suvar, Sonia Niculina; Bleiziffer, R; Podea, P; Iordache, A; Voica, C; Zgavarogea, R; Culea, M

    A major cause of cardiovascular diseases and cancer is diet content, so the optimization of micronutrients in food is very important. Omega-3 fatty acids supplementation for patients had beneficial effects on subjective global assessment score and metabolic profiles. Fatty acids content and the metal ions in different seeds (e.g. linseed, poppy, grape, hemp, nuts, pumpkin, sesame, watermelon, chia) recommended as food supplements, purchased on the Romanian market, were compared. Gas chromatography coupled to mass spectrometry (GC-MS) was used as an excellent technique for fatty acids identification and quantitation, and inductively coupled plasma mass spectrometer (ICP-MS) for analytical measurements of metals.

  11. Mass spectrometric measurements of SF sub 6 chemical releases from sounding rockets

    SciTech Connect

    Hunton, D.E.; Viggiano, A.A.; Swider, W.; Paulson, J.F.; Sherman, C. )

    1987-08-01

    Sulfur hexafluoride was released from a small reservoir on the side of a sounding rocket equipped with a negative ion mass spectrometer. The effects of the release were observed only at altitudes between 100 km and the rocket's apogee at 128 km. Below these altitudes the SF{sub 6} was swept away by the flow of atmospheric gases past the rocket. The maximum ion signals were observed at 115-118 km, where the mean free path equaled the distance form the reservoir to the mass spectrometer. The negative ions that resulted from the SF{sub 6} release were SF{sub 6}{sup {minus}}, SF{sub 5}{sup {minus}}, and O{sup {minus}}. At 155 km the relative intensities of these ions were 1.0, 0.3, 0.07, and 0.06, respectively. A large fraction of the SF{sub 6}{sup {minus}}*, and ion-molecule reactions. The mass spectrometer sampled a nonequilibrium distribution of ions in the first milliseconds after they were formed. In addition, the large draw-in field of the mass spectrometer probably altered the identities and relative intensities of the ions. Laboratory measurements with a selected ion flow tube apparatus show that the reaction SF{sub 5}{sup {minus}} + O {yields} F{sup {minus}} + SF{sub 4}O proceeds with rate constant 1.1 {times} 10{sup {minus}11} cm{sup 3} s{sup {minus}1} at 300 K.

  12. High-Resolution Mass Spectrometric Analysis of Secondary Organic Aerosol Produced by Ozonation of Limonene

    SciTech Connect

    Walser, Maggie L.; Dessiaterik, Yury; Laskin, Julia; Laskin, Alexander; Nizkorodov, Serguei

    2008-02-08

    Secondary organic aerosol (SOA) particles formed from the ozone-initiated oxidation of limonene are characterized by high-resolution electrospray ionization mass spectrometry in both the positive and negative ion modes. The mass spectra reveal a large number of both monomeric (m/z < 300) and oligomeric (m/z > 300) products of oxidation. A combination of high resolving power (m/Δm ~60,000) and Kendrick mass defect analysis makes it possible to unambiguously determine the composition for hundreds of individual compounds in SOA samples. Van Krevelen analysis shows that the SOA compounds are heavily oxidized, with average O:C ratios of 0.43 and 0.50 determined from the positive and negative ion mode spectra, respectively. An extended reaction mechanism for the formation of the first generation SOA molecular components is proposed. The mechanism includes known isomerization and addition reactions of the carbonyl oxide intermediates generated during the ozonation of limonene, and numerous isomerization pathways for alkoxy radicals resulting from the decomposition of unstable carbonyl oxides. The isomerization reactions yield numerous products with a progressively increasing number of alcohol and carbonyl groups, whereas C-C bond scission reactions in alkoxy radicals shorten the carbon chain. Together these reactions yield a large number of isomeric products with broadly distributed masses. A qualitative agreement is found between the number and degree of oxidation of the predicted and measured reaction products in the monomer range.

  13. Mass-spectrometric profiling of porphyrins in complex biological samples with fundamental, toxicological, and pharmacological applications

    PubMed Central

    Sullivan, Sarah A.; Streit, Bennett R.; Ferguson, Ethan L.; Jean, Paul A.; McNett, Debra A.; Llames, Louis T.; DuBois, Jennifer L.

    2015-01-01

    Rapid, high-throughput, and quantitative evaluations of biological metabolites in complex milieu are increasingly required for biochemical, toxicological, pharmacological, and environmental analyses. They are also essential for the development, testing, and improvement of new commercial chemical products. We demonstrate the application of ultra-high performance liquid chromatography-mass spectrometry (uHPLC-MS), employing an electrospray ionization source and a high accuracy quadrupole time-of-flight mass analyzer, for the identification and quantification of a series of porphyrin derivatives in liver: a matrix of particular relevance in toxicological or pharmacological testing. Exact mass is used to identify and quantify the metabolites. Chromatography enhances sensitivity and alleviates potential saturation issues by fanning out the contents of a complex sample before their injection into the spectrometer, but is not strictly necessary for the analysis. Extraction and sample treatment procedures are evaluated and matrix effects discussed. Using this method, the known mechanism of action of a well-characterized porphyrinogenic agent was verified in liver extracts from treated rats. The method was also validated for use with bacterial cells. This exact-mass method uses workhorse instruments available in many laboratories, providing a highly flexible alternative to existing HPLC- and MS/MS-based approaches for the simultaneous analysis of multiple compounds in biological media. PMID:25769421

  14. Spatially-Correlated Mass Spectrometric Analysis of Microbe-Mineral Interactions

    SciTech Connect

    Jill R. Scott; Beizhan Yan; Daphne L. Stoner

    2006-11-01

    A new methodology for examining the interactions of microbes with heterogeneous minerals is presented. Imaging laser-desorption Fourier transform mass spectrometry was used to examine the colonization patterns of Burkholderia vietnamiensis (Burkholderia cepacia) G4 on a heterogeneous basalt sample. Depth-profile imaging found that the bacterium preferentially colonized the plagioclase mineral phases within the basalt.

  15. Multiplex mass spectrometric imaging with polarity switching for concurrent acquisition of positive and negative ion images.

    PubMed

    Korte, Andrew R; Lee, Young Jin

    2013-06-01

    We have recently developed a multiplex mass spectrometry imaging (MSI) method which incorporates high mass resolution imaging and MS/MS and MS(3) imaging of several compounds in a single data acquisition utilizing a hybrid linear ion trap-Orbitrap mass spectrometer (Perdian and Lee, Anal. Chem. 82, 9393-9400, 2010). Here we extend this capability to obtain positive and negative ion MS and MS/MS spectra in a single MS imaging experiment through polarity switching within spiral steps of each raster step. This methodology was demonstrated for the analysis of various lipid class compounds in a section of mouse brain. This allows for simultaneous imaging of compounds that are readily ionized in positive mode (e.g., phosphatidylcholines and sphingomyelins) and those that are readily ionized in negative mode (e.g., sulfatides, phosphatidylinositols and phosphatidylserines). MS/MS imaging was also performed for a few compounds in both positive and negative ion mode within the same experimental set-up. Insufficient stabilization time for the Orbitrap high voltage leads to slight deviations in observed masses, but these deviations are systematic and were easily corrected with a two-point calibration to background ions.

  16. Mass spectrometric identification of cyclic polysulfides in sediment of the Eastern Gulf of Finland. II.

    PubMed

    Takhistov, Viatcheslav V; Khoroshko, Larisa O; Viktorovskii, Igor V; Lahtiperä, Mirja; Paasivirta, Jaakko

    2004-01-01

    Nine polysulfides, previously unknown as environmental organic pollutants, were analyzed from a sediment sample from the Eastern Gulf of Finland. The determinations were done by gas chromatography connected to low- and high-resolution mass spectrometers. The structure of the polysulfides was elucidated by determination of isotopic composition of abundant molecular and fragment ions by high-resolution mass spectrometry (HRMS), the interpretation of ion structures in low-resolution mass spectra (LMRS) using the thermochemical approach, the application of fragmentation rules and performing the ICLU simulation of abundance of ions in isotope clusters. Seven compounds were known in literature, but mass spectra were reported for only two of them, both recorded from mixture. Struture evaluation was successful for other substances, but not for the substance(s) in first eluting GC peak, where HRMS date were not obtained. Suggested structures of the cyclic compounds were (in the order of GC retention) 3,4-dithiacyclohexene, 1,2,3-trithiacyclohexane, 3,4,5- trithiacyclohexene, 1,2,4-trithiacyclohexane, cyclopropyl hydrodisulfide, 1,2-dithiole-3-thione and 1,2,3,4,5-penta- thiacyclo-octane. One acyclic congener identified was dimethyl tetrasulfide.

  17. ION COMPOSITION ELUCIDATION (ICE): A HIGH RESOLUTION MASS SPECTROMETRIC TECHNIQUE FOR IDENTIFYING COMPOUNDS IN COMPLEX MIXTURES

    EPA Science Inventory

    When tentatively identifying compounds in complex mixtures using mass spectral libraries, multiple matches or no plausible matches due to a high level of chemical noise or interferences can occur. Worse yet, most analytes are not in the libraries. In each case, Ion Composition El...

  18. Mass Spectrometric Identification of the Arginine and Lysine deficient Proline Rich Glutamine Rich Wheat Storage Proteins

    USDA-ARS?s Scientific Manuscript database

    Tandem mass spectrometry (MS/MS) of enzymatic digest has made possible identification of a wide variety of proteins and complex samples prepared by such techniques as RP-HPLC or 2-D gel electrophoresis. Success requires peptide fragmentation to be indicative of the peptide amino acid sequence. The f...

  19. ION COMPOSITION ELUCIDATION (ICE): A HIGH RESOLUTION MASS SPECTROMETRIC TECHNIQUE FOR IDENTIFYING COMPOUNDS IN COMPLEX MIXTURES

    EPA Science Inventory

    When tentatively identifying compounds in complex mixtures using mass spectral libraries, multiple matches or no plausible matches due to a high level of chemical noise or interferences can occur. Worse yet, most analytes are not in the libraries. In each case, Ion Composition El...

  20. Identification of the ESKAPE pathogens by mass spectrometric analysis of microbial membrane glycolipids.

    PubMed

    Leung, Lisa M; Fondrie, William E; Doi, Yohei; Johnson, J Kristie; Strickland, Dudley K; Ernst, Robert K; Goodlett, David R

    2017-07-25

    Rapid diagnostics that enable identification of infectious agents improve patient outcomes, antimicrobial stewardship, and length of hospital stay. Current methods for pathogen detection in the clinical laboratory include biological culture, nucleic acid amplification, ribosomal protein characterization, and genome sequencing. Pathogen identification from single colonies by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis of high abundance proteins is gaining popularity in clinical laboratories. Here, we present a novel and complementary approach that utilizes essential microbial glycolipids as chemical fingerprints for identification of individual bacterial species. Gram-positive and negative bacterial glycolipids were extracted using a single optimized protocol. Extracts of the clinically significant ESKAPE pathogens: E nterococcus faecium, S taphylococcus aureus, K lebsiella pneumoniae, A cinetobacter baumannii, P seudomonas aeruginosa, and E nterobacter spp. were analyzed by MALDI-TOF-MS in negative ion mode to obtain glycolipid mass spectra. A library of glycolipid mass spectra from 50 microbial entries was developed that allowed bacterial speciation of the ESKAPE pathogens, as well as identification of pathogens directly from blood bottles without culture on solid medium and determination of antimicrobial peptide resistance. These results demonstrate that bacterial glycolipid mass spectra represent chemical barcodes that identify pathogens, potentially providing a useful alternative to existing diagnostics.

  1. DETERMINATION OF BROMATE IN DRINKING WATERS BY ION CHROMATOGRAPHY WITH INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRIC DETECTION

    EPA Science Inventory

    Bromate is a disinfection by-product in drinking water, formed during the ozonation of source water containing bromide. An inductively coupled plasma mass spectrometer is combined with an ion chromatograph for the analysis of bromate in drinking waters. Three chromatographic colu...

  2. DETERMINATION OF BROMATE IN DRINKING WATERS BY ION CHROMATOGRAPHY WITH INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRIC DETECTION

    EPA Science Inventory

    Bromate is a disinfection by-product in drinking water, formed during the ozonation of source water containing bromide. An inductively coupled plasma mass spectrometer is combined with an ion chromatograph for the analysis of bromate in drinking waters. Three chromatographic colu...

  3. Collision-induced fragmentation accurate mass spectrometric analysis methods to rapidly characterize plant extracts

    USDA-ARS?s Scientific Manuscript database

    The rapid advances in analytical chromatography equipment have made the reliable and reproducible measurement of a wide range of plant chemical components possible. Full chemical characterization of a given plant material is possible with the new mass spectrometers currently available. For phytochem...

  4. Collision-induced fragmentation accurate mass spectrometric analysis methods to rapidly characterize plant extracts

    USDA-ARS?s Scientific Manuscript database

    The rapid advances in analytical chromatography equipment have made the reliable and reproducible measurement of a wide range of plant chemical components possible. Full chemical characterization of a given plant material is possible with the new mass spectrometers currently available. However, th...

  5. Collision-induced fragmentation accurate mass spectrometric analysis methods to rapidly characterize phytochemicals in plant extracts

    USDA-ARS?s Scientific Manuscript database

    The rapid advances in analytical chromatography equipment have made the reliable and reproducible measurement of a wide range of plant chemical components possible. Full chemical characterization of a given plant material is possible with the new mass spectrometers currently available. New methods a...

  6. Characterisation of archaeological waterlogged wood by pyrolytic and mass spectrometric techniques.

    PubMed

    Łucejko, Jeannette J; Modugno, Francesca; Ribechini, Erika; del Río, José C

    2009-11-03

    Two techniques based on analytical pyrolysis and mass spectrometry, direct exposure-MS (DE-MS) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), were used to characterise waterlogged archaeological wood and to study degradation patterns of wood in aqueous environments. The two techniques were applied to samples from the excavation of the Site of the Ancient Ships of Pisa San Rossore in Pisa (Italy), and data were compared to those relative to native sound wood of the same species (pine, elm, beech). Both the methods result valuable in the analysis of ancient wood artefacts, avoiding the long wet-chemical procedures that are commonly used in wood analysis, and allowing us to use a minimal sample size. DE-MS achieves a global mass spectral fingerprint of lignin and polysaccharides pyrolysis compounds in few minutes, and the results have been interpreted with the support of principal component analysis (PCA) of mass spectra. Py-GC/MS permits detailed molecular analysis of pyrolysis compounds and highlights some chemical modifications of lignin in archaeological samples, as demethylation of both guaiacyl and syringyl lignin units. Both the techniques demonstrate consistent loss of polysaccharides in archaeological wood.

  7. Simultaneous Orthogonal Drug Detection Using Fully Integrated Gas Chromatography with Fourier Transform Infrared Detection and Mass Spectrometric Detection.

    PubMed

    Lanzarotta, Adam; Falconer, Travis; McCauley, Heather; Lorenz, Lisa; Albright, Douglas; Crowe, John; Batson, JaCinta

    2017-05-01

    Analytes that co-elute and yield nearly identical electron ionization (EI) mass spectra, as well as analytes that yield non-specific EI fragmentation patterns, have been identified using fully integrated gas chromatography with direct deposit Fourier transform infrared detection and mass spectrometric detection (GC/FT-IR/MS). While the IR detector proved to be more selective for identifying analytes such as synthetic cannabinoids and weight loss drugs, it was limited by a relatively high detection limit of 8.4 parts per million (ppm) for non-targeted identification of sibutramine based on a single injection but was reduced to 840  parts per billion (ppb) for targeted identification of sibutramine by redepositing ten injections along the same track. The MS detector was less selective for identifying these analytes but yielded non-targeted and targeted detection limits of approximately 84 ppb and 8.4 ppb, respectively, which corresponded to a 100-fold advantage compared to the IR detector. Overall, the results of this study demonstrate that the advantages of each detector compensate for the limitations of the other, which allows a wider range of analytes and concentrations to be examined using a fully integrated GC/FT-IR/MS instrument compared to what can be examined using GC/IR or GC/MS independently. Not only does this approach reduce consumption of laboratory resources and time, it provides IR and MS information on the same sample, which is important for forensic analyses that require data from two or more orthogonal techniques to make an identification.

  8. OpenChrom: a cross-platform open source software for the mass spectrometric analysis of chromatographic data

    PubMed Central

    2010-01-01

    Background Today, data evaluation has become a bottleneck in chromatographic science. Analytical instruments equipped with automated samplers yield large amounts of measurement data, which needs to be verified and analyzed. Since nearly every GC/MS instrument vendor offers its own data format and software tools, the consequences are problems with data exchange and a lack of comparability between the analytical results. To challenge this situation a number of either commercial or non-profit software applications have been developed. These applications provide functionalities to import and analyze several data formats but have shortcomings in terms of the transparency of the implemented analytical algorithms and/or are restricted to a specific computer platform. Results This work describes a native approach to handle chromatographic data files. The approach can be extended in its functionality such as facilities to detect baselines, to detect, integrate and identify peaks and to compare mass spectra, as well as the ability to internationalize the application. Additionally, filters can be applied on the chromatographic data to enhance its quality, for example to remove background and noise. Extended operations like do, undo and redo are supported. Conclusions OpenChrom is a software application to edit and analyze mass spectrometric chromatographic data. It is extensible in many different ways, depending on the demands of the users or the analytical procedures and algorithms. It offers a customizable graphical user interface. The software is independent of the operating system, due to the fact that the Rich Client Platform is written in Java. OpenChrom is released under the Eclipse Public License 1.0 (EPL). There are no license constraints regarding extensions. They can be published using open source as well as proprietary licenses. OpenChrom is available free of charge at http://www.openchrom.net. PMID:20673335

  9. Mass spectrometric metabolomic imaging of biofilms on corroding steel surfaces using laser ablation and solvent capture by aspiration.

    PubMed

    Brauer, Jonathan I; Makama, Zakari; Bonifay, Vincent; Aydin, Egemen; Kaufman, Eric D; Beech, Iwona B; Sunner, Jan

    2015-03-02

    Ambient laser ablation and solvent capture by aspiration (LASCA) mass spectrometric imaging was combined with metabolomics high-performance liquid chromatography (HPLC) mass spectrometry analysis and light profilometry to investigate the correlation between chemical composition of marine bacterial biofilms on surfaces of 1018 carbon steel and corrosion damage of steel underneath the biofilms. Pure cultures of Marinobacter sp. or a wild population of bacteria present in coastal seawater served as sources of biofilms. Profilometry data of biofilm-free surfaces demonstrated heterogeneous distributions of corrosion damage. LASCA data were correlated with areas on the coupons varying in the level of corrosion attack, to reveal differences in chemical composition within biofilm regions associated with corroding and corrosion-free zones. Putative identification of selected compounds was carried out based on HPLC results and subsequent database searches. This is the first report of successful ambient chemical and metabolomic imaging of marine biofilms on corroding metallic materials. The metabolic analysis of such biofilms is challenging due to the presence in the biofilm of large amounts of corrosion products. However, by using the LASCA imaging interface, images of more than 1000 ions (potential metabolites) are generated, revealing striking heterogeneities within the biofilm. In the two model systems studied here, it is found that some of the patterns observed in selected ion images closely correlate with the occurrence and extent of corrosion in the carbon steel substrate as revealed by profilometry, while others do not. This approach toward the study of microbially influenced corrosion (MIC) holds great promise for approaching a fundamental understanding of the mechanisms involved in MIC.

  10. Optimization of quadrupole ion storage mass spectrometric conditions for the analysis of selected polybrominated diphenyl ethers. Comparative approach with negative chemical ionization and electron impact mass spectrometry.

    PubMed

    Larrazábal, David; Angeles Martínez, Ma; Eljarrat, Ethel; Barceló, Damiá; Fabrellas, Begoña

    2004-10-01

    Gas chromatography coupled to quadrupole ion storage mass spectrometry (QISTMS) operating in the non-resonant mode is presented as an innovative approach for the analysis of selected polybrominated diphenyl ethers (PBDEs). Although reductions in complexity and time needed for optimization are achieved in comparison with the resonant option, precise adjustment of the mass spectrometric conditions is required. Differences in isolation and fragmentation patterns of target species with degree of bromination were observed. The reliability of the method was confirmed by using standard solutions through the evaluation of certain quality parameters such as accuracy (92-108%), injection repeatability and reproducibility (coefficient of variation below 10% and 15%, respectively). Detection limits ranged from 62 to 621 fg, providing sensitivity similar to that of negative chemical ionisation (NCIMS) and greater than that of electron ionization mass spectrometry. The applicability of QISTMS method to real samples and matrix effects were evaluated through the analysis of some PBDE congeners in a sewage sludge sample from a Spanish waste-water treatment plant. Comparable results were obtained using QISTMS and NCIMS. According to these observations, QISTMS performed in the non-resonant mode may constitute a low-cost, rapid and reliable alternative to high-resolution devices for the analysis of selected PBDEs in environmental samples.

  11. Developing mass spectrometric techniques for boundary layer measurement in hypersonic high enthalpy test facilities

    NASA Technical Reports Server (NTRS)

    Wood, G. M., Jr.; Lewis, B. W.; Nowak, R. J.; Eide, D. G.; Paulin, P. A.; Upchurch, B. T.

    1983-01-01

    Thermodynamic flow properties of gases in the boundary layer or the flowfield have been mainly deduced from pressures and temperatures measured on a model. However, further progress with respect to an understanding of these properties requires a more complete characterization of the layer including determination of the gas composition and chemistry. Most attempts to measure boundary layer chemistry involve the employment of a mass spectrometer and an associated gas sampling system. The three major limiting factors which must be addressed for species measurement in aerothermodynamic investigations on models at reentry stream velocities, are gas sampling effects, instrument limitations, and problems with data acquisition. The present investigation is concerned with a concentrated effort to quantitatively identify and correct for instrument and sampling system effects, and to develop a miniaturized high performance mass spectrometer for on-model real-time analysis of the boundary layer and its associated atmosphere.

  12. Rarefied gas dynamic effects on mass spectrometric studies of upper planetary atmospheres

    NASA Technical Reports Server (NTRS)

    French, J. B.; Reid, N. M.; Nier, A. O.; Hayden, J. L.

    1975-01-01

    Results are presented of measurements obtained with an open-source mass spectrometer both in earth orbit and in a laboratory molecular beam facility. The mass spectrometer/ion source combination was developed in the laboratory to be operable in either of two modes by altering ion extraction potential on ground command, i.e., as a stagnation cavity or to respond only to the incoming molecules of the unperturbed atmosphere. Results indicate that the use of this open-source configuration and dual-mode capability, allied with both standard static calibration and dynamic calibration using high-speed molecular beam techniques in the laboratory, allows collection of useful data on aeronomy of the upper atmosphere of planets and comet tails.

  13. Rarefied gas dynamic effects on mass spectrometric studies of upper planetary atmospheres

    NASA Technical Reports Server (NTRS)

    French, J. B.; Reid, N. M.; Nier, A. O.; Hayden, J. L.

    1975-01-01

    Results are presented of measurements obtained with an open-source mass spectrometer both in earth orbit and in a laboratory molecular beam facility. The mass spectrometer/ion source combination was developed in the laboratory to be operable in either of two modes by altering ion extraction potential on ground command, i.e., as a stagnation cavity or to respond only to the incoming molecules of the unperturbed atmosphere. Results indicate that the use of this open-source configuration and dual-mode capability, allied with both standard static calibration and dynamic calibration using high-speed molecular beam techniques in the laboratory, allows collection of useful data on aeronomy of the upper atmosphere of planets and comet tails.

  14. Mass Spectrometric Immunoassay for Parathyroid Hormone Related Protein (PTHrP)

    SciTech Connect

    Zheng, K.; Rivera, J.D.; Vogel, J.S.; Buchholz, B.A.; Burton, D.W.; Deftos, L.J.; Herold, D.A.; Fitzgerald, R.L.

    2000-06-16

    Many cancers, including prostate, breast and lung express parathyroid hormone related protein (PTHrP). Despite the common tumor overexpression of PTHrP, serum levels of PTHrP are not commonly elevated in affected patients. They postulate that the reasons for the discrepancy between tissue and serum measurements of PTHrP are the inadequate sensitivity and specificity of current PTHrP serum assays. To improve the clinical value of PTHrP serum assays for the cancer patient, they are developing a new generation of novel and ultrasensitive PTHrP serum immunoassays based on immunoaffinity purification, nanospray liquid chromatography tandem mass spectrometry (LC/MS/MS) and accelerator mass spectrometry (AMS).

  15. Dual-Mode Mass Spectrometric Imaging for Determination of in Vivo Stability of Nanoparticle Monolayers.

    PubMed

    Elci, S Gokhan; Yesilbag Tonga, Gulen; Yan, Bo; Kim, Sung Tae; Kim, Chang Soo; Jiang, Ying; Saha, Krishnendu; Moyano, Daniel F; Marsico, Alyssa L M; Rotello, Vincent M; Vachet, Richard W

    2017-07-25

    Effective correlation of the in vitro and in vivo stability of nanoparticle-based platforms is a key challenge in their translation into the clinic. Here, we describe a dual imaging method that site-specifically reports the stability of monolayer-functionalized nanoparticles in vivo. This approach uses laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) imaging to monitor the distributions of the nanoparticle core material and laser desorption/ionization mass spectrometry (LDI-MS) imaging to report on the monolayers on the nanoparticles. Quantitative comparison of the images reveals nanoparticle stability at the organ and suborgan level. The stability of particles observed in the spleen was location-dependent and qualitatively similar to in vitro studies. In contrast, in vivo stability of the nanoparticles in the liver differed dramatically from in vitro studies, demonstrating the importance of in vivo assessment of nanoparticle stability.

  16. Liquid chromatography/electrospray ionization mass spectrometric characterization of Harpagophytum in equine urine and plasma.

    PubMed

    Colas, Cyril; Garcia, Patrice; Popot, Marie-Agnès; Bonnaire, Yves; Bouchonnet, Stéphane

    2006-01-01

    A method has been developed for the analysis and characterization in equine urine and plasma of iridoid glycosides: harpagide, harpagoside and 8-para-coumaroyl harpagide, which are the main active principles of Harpagophytum, a plant with antiinflammatory properties. The method involves liquid chromatography coupled with positive electrospray ionization mass spectrometry. The addition of sodium or lithium chloride instead of formic acid in the eluting solvent has been studied in order to enhance the signal and to modify the ion's internal energy. Fragmentation pathways and associated patterns are proposed for each analyte. A comparison of three types of mass spectrometer: a 3D ion trap, a triple quadrupole and a linear ion trap, has been conducted. The 3D ion trap was selected for drug screening analysis whereas the linear ion trap was retained for identification and quantitation analysis.

  17. Mass spectrometric methods prove the use of beeswax and ruminant fat in late Roman cooking pots.

    PubMed

    Kimpe, K; Jacobs, P A; Waelkens, M

    2002-08-30

    Lipid extracts of sherds of archaeological late Roman cooking pots were analysed using high temperature-gas chromatography coupled to a mass spectrometer and liquid chromatography with atmospheric pressure chemical ionization mass spectrometer detection (LC-APCI-MS). With these advanced techniques the use of beeswax was shown through identification of the constituting alkanes, mono and diesters. The detection of high amounts of saturated triacylglycerols (TAGs) further indicated that animal fat was processed in these pots. Part of the animal fat was characterised as originating from ruminants due to the presence of trans-fatty acids. The distribution of saturated TAGs and the higher concentration of stearic acid compared to palmitic acid in the transesterified lipid extract indicated that this was sheep fat. The results illustrate how complex mixtures can be unravelled and original contents of ancient ceramic vessels can be determined using specialised analytical equipment.

  18. Mass Spectrometric Detection of Botulinum Neurotoxin by Measuring its Activity in Serum and Milk

    NASA Astrophysics Data System (ADS)

    Kalb, Suzanne R.; Pirkle, James L.; Barr, John R.

    Botulinum neurotoxins (BoNTs) are bacterial protein toxins which are considered likely agents for bioterrorism due to their extreme toxicity and high availability. A new mass spectrometry based assay called Endopep MS detects and defines the toxin serotype in clinical and food matrices via toxin activity upon a peptide substrate which mimics the toxin's natural target. Furthermore, the subtype of the toxin is differentiated by employing mass spectrometry based proteomic techniques on the same sample. The Endopep-MS assay selectively detects active BoNT and defines the serotype faster and with sensitivity greater than the mouse bioassay. One 96-well plate can be analyzed in under 7 h. On higher level or "hot" samples, the subtype can then be differentiated in less than 2 h with no need for DNA.

  19. Production, partial characterization and mass spectrometric studies of the extracellular laccase activity from Fusarium proliferatum.

    PubMed

    Fernaud, J R Hernández; Marina, A; González, K; Vázquez, J; Falcón, M A

    2006-03-01

    Benzyl alcohol and starch-free commercial wheat bran were effective inducers of the laccase activity in cultures of Fusarium proliferatum (MUCL 31970). Initial pH value in the cultures was also an overriding factor for increasing its production. By gel permeation high-performance liquid chromatography, the enzyme eluted as an apparently homogeneous peak with a molecular mass of 54 kDa, but by isoelectrofocusing, two proteins with pI values of 5.17 and 5.07 were revealed. Two different phenoloxidase activities were also detected after nondenaturing polyacrylamide gel electrophoresis. By matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS), both proteins showed unique fingerprints, so they were classifiable as isozymes, and were named laccase 1 (Lac1, pI 5.17) and laccase 2 (Lac2, pI 5.07). No clear matches were found when compared with other proteins. The tandem mass spectrometry of some peptides from both isozymes reanalyzed by nanoelectron ionization-ion trap-mass spectrometry (nESI-IT-MS) confirmed their unique character. The following interesting properties, particularly its stability at alkaline pH, make this laccase a promising industrial enzyme for biotechnological applications: maximum activity at 60 degrees C, thermal stability for 2 h at 40 degrees C, optimum pH 3.5 (km=62 microM) measured on 2,2'-azino-bis(3-ethylbenz-thiazoline-6-sulfonate), and pH stability 4-8 (75% stability at pH levels 2.2 and 9) for 2 h at 25 degrees C.

  20. Mass spectrometric techniques for label-free high-throughput screening in drug discovery.

    PubMed

    Roddy, Thomas P; Horvath, Christopher R; Stout, Steven J; Kenney, Kristin L; Ho, Pei-I; Zhang, Ji-Hu; Vickers, Chad; Kaushik, Virendar; Hubbard, Brian; Wang, Y Karen

    2007-11-01

    High-throughput screening (HTS) is an important tool for finding active compounds to initiate medicinal chemistry programs in pharmaceutical discovery research. Traditional HTS methods rely on fluorescent or radiolabeled reagents and/or coupling assays to permit quantitation of enzymatic target inhibition or activation. Mass spectrometry-based high-throughput screening (MS-HTS) is an alternative that is not susceptible to the limitations imposed by labeling and coupling enzymes. MS-HTS offers a selective and sensitive analytical method for unlabeled substrates and products. Furthermore, method development times are reduced without the need to incorporate labels or coupling assays. MS-HTS also permits screening of targets that are difficult or impossible to screen by other techniques. For example, enzymes that are challenging to purify can lead to the nonspecific detection of structurally similar components of the impure enzyme or matrix of membraneous enzymes. The high selectivity of tandem mass spectrometry (MS/MS) enables these screens to proceed with low levels of background noise to sensitively discover interesting hits even with relatively weak activity. In this article, we describe three techniques that we have adapted for large-scale (approximately 175,000 sample) compound library screening, including four-way parallel multiplexed electrospray liquid chromatography tandem mass spectrometry (MUX-LC/MS/MS), four-way parallel staggered gradient liquid chromatography tandem mass spectrometry (LC/MS/MS), and eight-way staggered flow injection MS/MS following 384-well plate solid-phase extraction (SPE). These methods are capable of analyzing a 384-well plate in 37 min, with typical analysis times of less than 2 h. The quality of the MS-HTS approach is demonstrated herein with screening data from two large-scale screens.

  1. Mass-spectrometric determination of serum cortisol: comparison of data from two independent laboratories

    SciTech Connect

    Gaskell, S.J.; Sieckmann, L.

    1986-03-01

    Isotope dilution and mass spectrometry were used in two independent laboratories to determine cortisol in 15 plasma and serum pools used in the British and German national schemes for the external quality assessment of routine assays. For the concentration range 240-700 nmol/L, differences between the data obtained by the two laboratories were generally less than 4% but were approximately 7% in two instances. The discrepancies are nevertheless small in comparison with the bias observed for many routine assays.

  2. Gas chromatographic/mass spectrometric determination of lysergic acid diethylamide (LSD) in serum samples.

    PubMed

    Musshoff, F; Daldrup, T

    1997-08-04

    A sensitive method for the detection and quantification of lysergic acid diethylamide (LSD) in serum samples is described. After liquid-liquid extraction the trimethylsilyl derivative of LSD is detected by gas chromatography-mass spectrometry. Experiments with spiked samples resulted in a recovery of 76%, the coefficient of variation was 9.3%. Excellent linearity was obtained over the range 0.1-10 ng ml-1. Additionally experiments demonstrating the light sensitivity of LSD are presented together with casuistics.

  3. Rapid mass spectrometric DNA diagnostics for assessing microbial community activity during bioremediation. 1997 annual progress report

    SciTech Connect

    Benner, W.H.; Hunter-Cevera, J.

    1997-01-01

    'The effort of the past year''s activities, which covers the first year of the project, was directed at developing DNA-based diagnostic procedures for implementation in high through-put analytical instrumentation. The diagnostic procedures under evaluation are designed to identify specific genes in soil microorganisms that code for pollutant-degrading enzymes. Current DNA-based diagnostic procedures, such as the ligase chain reaction (LCR) and the polymerase chain reaction (PCR), rely on gel electrophoresis as a way to score a diagnostic test. The authors are attempting to implement time-of-flight (TOF) mass spectrometry as a replacement for gel separations because of its speed advantage and potential for sample automation. The authors anticipate that if TOF techniques can be implemented in the procedures, then a very large number of microorganisms and soil samples can be screened for the presence of specific pollutant-degrading genes. The use of DNA-based procedures for the detection of biodegrading organisms or genes that code for pollutant-degrading enzymes constitutes a critical technology for following biochemical transformation and substantiating the impact of bioremediation. DNA-based technology has been demonstrated to be a sensitive technique for tracking micro-organism activity at the molecular level. These procedures can be tuned to identify groups of organisms, specific organisms, and activity at the molecular level. They are developing a P-monitoring strategy that relies on the combined use of DNA diagnostics with mass spectrometry as the detection scheme. The intent of this work is a two-fold evaluation of (1) the feasibility of replacing the use of gel separations for identifying polymerase chain reaction (PCR) products with a rapid and automatable form of electrospray mass spectrometry and (2) the use of matrix-assisted-laser-desorption-ionization mass spectrometry (MALDI-MS) as a tool to score oligonucleotide ligation assays (OLA).'

  4. Mass spectrometric analysis and aerodynamic properties of various types of combustion-related aerosol particles

    NASA Astrophysics Data System (ADS)

    Schneider, J.; Weimer, S.; Drewnick, F.; Borrmann, S.; Helas, G.; Gwaze, P.; Schmid, O.; Andreae, M. O.; Kirchner, U.

    2006-12-01

    Various types of combustion-related particles in the size range between 100 and 850 nm were analyzed with an aerosol mass spectrometer and a differential mobility analyzer. The measurements were performed with particles originating from biomass burning, diesel engine exhaust, laboratory combustion of diesel fuel and gasoline, as well as from spark soot generation. Physical and morphological parameters like fractal dimension, effective density, bulk density and dynamic shape factor were derived or at least approximated from the measurements of electrical mobility diameter and vacuum aerodynamic diameter. The relative intensities of the mass peaks in the mass spectra obtained from particles generated by a commercial diesel passenger car, by diesel combustion in a laboratory burner, and by evaporating and re-condensing lubrication oil were found to be very similar. The mass spectra from biomass burning particles show signatures identified as organic compounds like levoglucosan but also others which are yet unidentified. The aerodynamic behavior yielded a fractal dimension (Df) of 2.09 +/- 0.06 for biomass burning particles from the combustion of dry beech sticks, but showed values around three, and hence more compact particle morphologies, for particles from combustion of more natural oak. Scanning electron microscope images confirmed the finding that the beech combustion particles were fractal-like aggregates, while the oak combustion particles displayed a much more compact shape. For particles from laboratory combusted diesel fuel, a Df value of 2.35 was found, for spark soot particles, Df [approximate] 2.10. The aerodynamic properties of fractal-like particles from dry beech wood combustion indicate an aerodynamic shape factor [chi] that increases with electrical mobility diameter, and a bulk density of 1.92 g cm-3. An upper limit of [chi] [approximate] 1.2 was inferred for the shape factor of the more compact particles from oak combustion.

  5. Resonance ionization mass spectrometric study of the promethium/samarium isobaric pair

    SciTech Connect

    Shaw, R.W.; Young, J.P.; Smith, D.H.

    1988-01-01

    Samarium daughters are problematic in isotope ratio measurements of promethium because they are isobaric. Resonance ionization mass spectrometry was utilized to circumvent this problem. An ionization selectivity factor of at least 1000:1 has been measured for promethium over samarium at 584.6 nm. Resonance ionization spectra have been recorded for both elements over the 528-560 and 580-614 nm wavelength ranges.

  6. Flavonoids as matrices for MALDI-TOF mass spectrometric analysis of transition metal complexes

    NASA Astrophysics Data System (ADS)

    Petkovic, Marijana; Petrovic, Biljana; Savic, Jasmina; Bugarcic, Zivadin D.; Dimitric-Markovic, Jasmina; Momic, Tatjana; Vasic, Vesna

    2010-02-01

    Matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a suitable method for the analysis of inorganic and organic compounds and biomolecules. This makes MALDI-TOF MS convenient for monitoring the interaction of metallo-drugs with biomolecules. Results presented in this manuscript demonstrate that flavonoids such as apigenin, kaempferol and luteolin are suitable for MALDI-TOF MS analysis of Pt(II), Pd(II), Pt(IV) and Ru(III) complexes, giving different signal-to-noise ratios of the analyte peak. The MALDI-TOF mass spectra of inorganic complexes acquired with these flavonoid matrices are easy to interpret and have some advantages over the application of other commonly used matrices: a low number of matrix peaks are detectable and the coordinative metal-ligand bond is, in most cases, preserved. On the other hand, flavonoids do not act as typical matrices, as their excess is not required for the acquisition of MALDI-TOF mass spectra of inorganic complexes.

  7. High Throughput Ambient Mass Spectrometric Approach to Species Identification and Classification from Chemical Fingerprint Signatures

    DOE PAGES

    Musah, Rabi A.; Espinoza, Edgard O.; Cody, Robert B.; ...

    2015-07-09

    A high throughput method for species identification and classification through chemometric processing of direct analysis in real time (DART) mass spectrometry-derived fingerprint signatures has been developed. The method entails introduction of samples to the open air space between the DART ion source and the mass spectrometer inlet, with the entire observed mass spectral fingerprint subjected to unsupervised hierarchical clustering processing. Moreover, a range of both polar and non-polar chemotypes are instantaneously detected. The result is identification and species level classification based on the entire DART-MS spectrum. In this paper, we illustrate how the method can be used to: (1) distinguishmore » between endangered woods regulated by the Convention for the International Trade of Endangered Flora and Fauna (CITES) treaty; (2) assess the origin and by extension the properties of biodiesel feedstocks; (3) determine insect species from analysis of puparial casings; (4) distinguish between psychoactive plants products; and (5) differentiate between Eucalyptus species. An advantage of the hierarchical clustering approach to processing of the DART-MS derived fingerprint is that it shows both similarities and differences between species based on their chemotypes. Furthermore, full knowledge of the identities of the constituents contained within the small molecule profile of analyzed samples is not required.« less

  8. High Throughput Ambient Mass Spectrometric Approach to Species Identification and Classification from Chemical Fingerprint Signatures

    SciTech Connect

    Musah, Rabi A.; Espinoza, Edgard O.; Cody, Robert B.; Lesiak, Ashton D.; Christensen, Earl D.; Moore, Hannah E.; Maleknia, Simin; Drijhout, Falko P.

    2015-07-09

    A high throughput method for species identification and classification through chemometric processing of direct analysis in real time (DART) mass spectrometry-derived fingerprint signatures has been developed. The method entails introduction of samples to the open air space between the DART ion source and the mass spectrometer inlet, with the entire observed mass spectral fingerprint subjected to unsupervised hierarchical clustering processing. Moreover, a range of both polar and non-polar chemotypes are instantaneously detected. The result is identification and species level classification based on the entire DART-MS spectrum. In this paper, we illustrate how the method can be used to: (1) distinguish between endangered woods regulated by the Convention for the International Trade of Endangered Flora and Fauna (CITES) treaty; (2) assess the origin and by extension the properties of biodiesel feedstocks; (3) determine insect species from analysis of puparial casings; (4) distinguish between psychoactive plants products; and (5) differentiate between Eucalyptus species. An advantage of the hierarchical clustering approach to processing of the DART-MS derived fingerprint is that it shows both similarities and differences between species based on their chemotypes. Furthermore, full knowledge of the identities of the constituents contained within the small molecule profile of analyzed samples is not required.

  9. Mass spectrometric approaches for chemical characterisation of atmospheric aerosols: critical review of the most recent advances

    SciTech Connect

    Laskin, Alexander; Laskin, Julia; Nizkorodov, Sergey A.

    2012-06-29

    This manuscript presents an overview of the most recent instrument developments for the field and laboratory applications of mass spectrometry (MS) to investigate the chemistry and physics of atmospheric aerosols. A range of MS instruments, employing different sample introduction methods, ionisation and mass detection techniques are used both for ‘online’ and ‘offline’ characterisation of aerosols. Online MS techniques enable detection of individual particles with simultaneous measurement of particle size distributions and aerodynamic characteristics and are ideally suited for field studies that require high temporal resolution. Offline MS techniques provide a means for detailed molecular-level analysis of aerosol samples, which is essential to gain fundamental knowledge regarding aerosol chemistry, mechanisms of particle formation and atmospheric aging. Combined, complementary MS techniques provide comprehensive information on the chemical composition, size, morphology and phase of aerosols – data of key importance for evaluating hygroscopic and optical properties of particles, their health effects, understanding their origins and atmospheric evolution. Over the last few years, developments and applications of MS techniques in aerosol research have expanded remarkably as evident by skyrocketing publication statistics. Finally, the goal of this review is to present the most recent developments in the field of aerosol mass spectrometry for the time period of late 2010 to early 2012, which have not been conveyed in previous reviews.

  10. A High Throughput Ambient Mass Spectrometric Approach to Species Identification and Classification from Chemical Fingerprint Signatures

    NASA Astrophysics Data System (ADS)

    Musah, Rabi A.; Espinoza, Edgard O.; Cody, Robert B.; Lesiak, Ashton D.; Christensen, Earl D.; Moore, Hannah E.; Maleknia, Simin; Drijfhout, Falko P.

    2015-07-01

    A high throughput method for species identification and classification through chemometric processing of direct analysis in real time (DART) mass spectrometry-derived fingerprint signatures has been developed. The method entails introduction of samples to the open air space between the DART ion source and the mass spectrometer inlet, with the entire observed mass spectral fingerprint subjected to unsupervised hierarchical clustering processing. A range of both polar and non-polar chemotypes are instantaneously detected. The result is identification and species level classification based on the entire DART-MS spectrum. Here, we illustrate how the method can be used to: (1) distinguish between endangered woods regulated by the Convention for the International Trade of Endangered Flora and Fauna (CITES) treaty; (2) assess the origin and by extension the properties of biodiesel feedstocks; (3) determine insect species from analysis of puparial casings; (4) distinguish between psychoactive plants products; and (5) differentiate between Eucalyptus species. An advantage of the hierarchical clustering approach to processing of the DART-MS derived fingerprint is that it shows both similarities and differences between species based on their chemotypes. Furthermore, full knowledge of the identities of the constituents contained within the small molecule profile of analyzed samples is not required.

  11. Combined computational metabolite prediction and automated structure-based analysis of mass spectrometric data.

    PubMed

    Stranz, David D; Miao, Shichang; Campbell, Scott; Maydwell, George; Ekins, Sean

    2008-01-01

    ABSTRACT As high-throughput technologies have developed in the pharmaceutical industry, the demand for identification of possible metabolites using predominantly liquid chromatographic/mass spectrometry-mass spectrometry/mass spectrometry (LC/MS-MS/MS) for a large number of molecules in drug discovery has also increased. In parallel, computational technologies have also been developed to generate predictions for metabolites alongside methods to predict MS spectra and score the quality of the match with experimental spectra. The goal of the current study was to generate metabolite predictions from molecular structure with a software product, MetaDrug. In vitro microsomal incubations were used to ultimately produce MS data that could be used to verify the predictions with Apex, which is a new software tool that can predict the molecular ion spectrum and a fragmentation spectrum, automating the detailed examination of both MS and MS/MS spectra. For the test molecule imipramine used to illustrate the combined in vitro/in silico process proposed, MetaDrug predicts 16 metabolites. Following rat microsomal incubations with imipramine and analysis of the MS(n) data using the Apex software, strong evidence was found for imipramine and five metabolites and weaker evidence for five additional metabolites. This study suggests a new approach to streamline MS data analysis using a combination of predictive computational approaches with software capable of comparing the predicted metabolite output with empirical data when looking at drug metabolites.

  12. Ultrahigh resolution mass spectrometric characterization of organic aerosol from European and Chinese cities

    NASA Astrophysics Data System (ADS)

    Wang, Kai; Huang, Ru-Jin; Hoffmann, Thorsten

    2016-04-01

    Organic aerosol constitutes a substantial fraction (20-90%) of submicrometer aerosol mass, playing an important role in air quality and human health. Over the past few years, ultra-high resolution mass spectrometry (UHRMS) has been applied to elucidate the chemical composition of ambient aerosols. However, most of the UHRMS studies used direct infusion without prior separation by liquid chromatography, which may cause the loss of individual compound information and interference problems. In the present study, urban ambient aerosol with particle diameter < 2.5 μm was collected in Mainz, Germany and Beijing, China, respectively. Two pretreatment procedures were applied to extract the organic compounds from the filter samples: One method uses a mixture of acetonitrile and water, the other uses pure water and prepared for the extraction of humic-like substances. The extracts were analyzed by ultra-high-performance liquid chromatography coupled with an Orbitrap mass spectrometer in both negative and the positive modes. The effects of pretreatment procedures on the characterization of organic aerosol and the city-wise difference in chemical composition of organic aerosol will be discussed in detail.

  13. Membrane Inlet for Mass Spectrometric Measurement of Catalysis by Enzymatic Decarboxylases

    PubMed Central

    Moral, Mario E. G.; Tu, Chingkuang; Richards, Nigel G. J.; Silverman, David N.

    2011-01-01

    Membrane inlet mass spectrometry (MIMS) uses diffusion across a permeable membrane to detect in solution uncharged molecules of small molecular weight. We point out here the application of MIMS to determine catalytic properties of decarboxylases using as an example catalysis by oxalate decarboxylase (OxDC) from Bacillus subtilis. The decarboxylase activity generates carbon dioxide and formate from the non-oxidative reaction, but is accompanied by a concomitant oxidase activity that consumes oxalate and oxygen and generates CO2 and hydrogen peroxide. The application of MIMS in measuring catalysis by OxDC involves the real-time and continuous detection of oxygen and product CO2 from the ion currents of their respective mass peaks. Steady-state catalytic constants for the decarboxylase activity obtained by measuring product CO2 using MIMS are comparable to those acquired by the traditional endpoint assay based on the coupled reaction with formate dehydrogenase, and measuring consumption of O2 using MIMS also estimates the oxidase activity. Use of isotope-labeled substrate (13C2-enriched oxalate) in MIMS provides a method to characterize the catalytic reaction in cell suspensions by detecting the mass peak for product 13CO2 (m/z 45), avoiding inaccuracies due to endogenous 12CO2. PMID:21782782

  14. Membrane inlet for mass spectrometric measurement of catalysis by enzymatic decarboxylases.

    PubMed

    Moral, Mario E G; Tu, Chingkuang; Richards, Nigel G J; Silverman, David N

    2011-11-01

    Membrane inlet mass spectrometry (MIMS) uses diffusion across a permeable membrane to detect in solution uncharged molecules of small molecular weight. We point out here the application of MIMS to determine catalytic properties of decarboxylases using as an example catalysis by oxalate decarboxylase (OxDC) from Bacillus subtilis. The decarboxylase activity generates carbon dioxide and formate from the nonoxidative reaction but is accompanied by a concomitant oxidase activity that consumes oxalate and oxygen and generates CO(2) and hydrogen peroxide. The application of MIMS in measuring catalysis by OxDC involves the real-time and continuous detection of oxygen and product CO(2) from the ion currents of their respective mass peaks. Steady-state catalytic constants for the decarboxylase activity obtained by measuring product CO(2) using MIMS are comparable to those acquired by the traditional endpoint assay based on the coupled reaction with formate dehydrogenase, and measuring consumption of O(2) using MIMS also estimates the oxidase activity. The use of isotope-labeled substrate ((13)C(2)-enriched oxalate) in MIMS provides a method to characterize the catalytic reaction in cell suspensions by detecting the mass peak for product (13)CO(2) (m/z 45), avoiding inaccuracies due to endogenous (12)CO(2). Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Mass Spectrometric Quantification of Histone Post-translational Modifications by a Hybrid Chemical Labeling Method

    PubMed Central

    Maile, Tobias M.; Izrael-Tomasevic, Anita; Cheung, Tommy; Guler, Gulfem D.; Tindell, Charles; Masselot, Alexandre; Liang, Jun; Zhao, Feng; Trojer, Patrick; Classon, Marie; Arnott, David

    2015-01-01

    Mass spectrometry is a powerful alternative to antibody-based methods for the analysis of histone post-translational modifications (marks). A key development in this approach was the deliberate propionylation of histones to improve sequence coverage across the lysine-rich and hydrophilic tails that bear most modifications. Several marks continue to be problematic however, particularly di- and tri-methylated lysine 4 of histone H3 which we found to be subject to substantial and selective losses during sample preparation and liquid chromatography-mass spectrometry. We developed a new method employing a “one-pot” hybrid chemical derivatization of histones, whereby an initial conversion of free lysines to their propionylated forms under mild aqueous conditions is followed by trypsin digestion and labeling of new peptide N termini with phenyl isocyanate. High resolution mass spectrometry was used to collect qualitative and quantitative data, and a novel web-based software application (Fishtones) was developed for viewing and quantifying histone marks in the resulting data sets. Recoveries of 53 methyl, acetyl, and phosphoryl marks on histone H3.1 were improved by an average of threefold overall, and over 50-fold for H3K4 di- and tri-methyl marks. The power of this workflow for epigenetic research and drug discovery was demonstrated by measuring quantitative changes in H3K4 trimethylation induced by small molecule inhibitors of lysine demethylases and siRNA knockdown of epigenetic modifiers ASH2L and WDR5. PMID:25680960

  16. Chemical, mass spectrometric, spectrochemical, nuclear, and radiochemical analysis of uranium hexafluoride

    SciTech Connect

    Not Available

    1981-01-01

    Analytical procedures, which are in routine use to determine conformance to uranium hexafluoride (UF/sub 6/) specifications in the Department of Energy gaseous diffusion plants or at other installations, are described in detail. Included are: subsampling of UF/sub 6/; gravimetric determination of uranium; titrimetric determination of uranium and of chlorine; preparation of high-purity U/sub 3/O/sub 8/; isotopic analysis by double-standard and by single-standard mass-spectrometer method; determination of hydrocarbons, chlorocarbons, and partially substituted halohydrocarbons; atomic absorption determination of antimony, ruthenium, and metallic impurities; spectrophotometric determination of bromine, silicon and phosphorus, titanium and vanadium, tungsten, thorium, and molybdenum; spectrographic determination of boron and silicon, ruthenium, thorium and rare earths; spectrographic determination of metallic impurities by carrier distillation; spectrographic determination of hafnium, molybdenum, niobium, tantalum, titanium, tungsten, vanadium, and zirconium after separation from UF/sub 6/ with BPHA and as cupferrides; impurity determination by spark-source mass spectrography; determination of boron-equivalent neutron cross section; determination of uranium-233 abundance by thermal ionization mass spectrometry; determination of uranium-232 by alpha spectrometry; determination of fission product activity by beta and gamma counting; determination of plutonium by ion exchange and alpha counting;determination of technetium-99 in UF/sub 6/; determination of gamma-energy emission rate from fission products in UF/sub 6/; determination of plutonium and neptunium by extraction and alpha counting; atomic absorption determination of chromium soluble and insoluble in UF/sub 6/. (JMT)

  17. A High Throughput Ambient Mass Spectrometric Approach to Species Identification and Classification from Chemical Fingerprint Signatures

    PubMed Central

    Musah, Rabi A.; Espinoza, Edgard O.; Cody, Robert B.; Lesiak, Ashton D.; Christensen, Earl D.; Moore, Hannah E.; Maleknia, Simin; Drijfhout, Falko P.

    2015-01-01

    A high throughput method for species identification and classification through chemometric processing of direct analysis in real time (DART) mass spectrometry-derived fingerprint signatures has been developed. The method entails introduction of samples to the open air space between the DART ion source and the mass spectrometer inlet, with the entire observed mass spectral fingerprint subjected to unsupervised hierarchical clustering processing. A range of both polar and non-polar chemotypes are instantaneously detected. The result is identification and species level classification based on the entire DART-MS spectrum. Here, we illustrate how the method can be used to: (1) distinguish between endangered woods regulated by the Convention for the International Trade of Endangered Flora and Fauna (CITES) treaty; (2) assess the origin and by extension the properties of biodiesel feedstocks; (3) determine insect species from analysis of puparial casings; (4) distinguish between psychoactive plants products; and (5) differentiate between Eucalyptus species. An advantage of the hierarchical clustering approach to processing of the DART-MS derived fingerprint is that it shows both similarities and differences between species based on their chemotypes. Furthermore, full knowledge of the identities of the constituents contained within the small molecule profile of analyzed samples is not required. PMID:26156000

  18. Novel LC/MS/MS and High-Throughput Mass Spectrometric Assays for Monoacylglycerol Acyltransferase Inhibitors.

    PubMed

    Qi, Jenson; Masucci, John A; Lang, Wensheng; Connelly, Margery A; Caldwell, Gary W; Petrounia, Ioanna; Kirkpatrick, Jennifer; Barnakov, Alexander N; Struble, Geoffrey; Miller, Robyn; Dzordzorine, Keli; Kuo, Gee-Hong; Gaul, Michael; Pocai, Alessandro; Lee, Seunghun

    2017-04-01

    Monoacylglycerol acyltransferase enzymes (MGAT1, MGAT2, and MGAT3) convert monoacylglycerol to diacylglycerol (DAG). MGAT1 and MGAT2 are both implicated in obesity-related metabolic diseases. Conventional MGAT enzyme assays use radioactive substrates, wherein the product of the MGAT-catalyzed reaction is usually resolved by time-consuming thin layer chromatography (TLC) analysis. Furthermore, microsomal membrane preparations typically contain endogenous diacylglycerol acyltransferase (DGAT) from the host cells, and these DGAT activities can further acylate DAG to form triglyceride (TG). Our mass spectrometry (liquid chromatography-tandem mass spectrometry, or LC/MS/MS) MGAT2 assay measures human recombinant MGAT2-catalyzed formation of didecanoyl-glycerol from 1-decanoyl-rac-glycerol and decanoyl-CoA, to produce predominantly 1,3-didecanoyl-glycerol. Unlike 1,2-DAG, 1,3-didecanoyl-glycerol is proved to be not susceptible to further acylation to TG. 1,3-Didecanoyl-glycerol product can be readily solubilized and directly subjected to high-throughput mass spectrometry (HTMS) without further extraction in a 384-well format. We also have established the LC/MS/MS MGAT activity assay in the intestinal microsomes from various species. Our assay is proved to be highly sensitive, and thus it allows measurement of endogenous MGAT activity in cell lysates and tissue preparations. The implementation of the HTMS MGAT activity assay has facilitated the robust screening and evaluation of MGAT inhibitors for the treatment of metabolic diseases.

  19. Capillary liquid chromatography using laser-based and mass spectrometric detection. Final technical progress report, September 1, 1989--January 31, 1993

    SciTech Connect

    Sepaniak, M.J.; Cook, K.D.

    1992-09-01

    In the years following the 1986 seminal paper (J. Chromatogr. Sci., 24, 347-352) describing modern capillary zone electrophoresis (CZE), the prominence of capillary electrokinetic separation techniques has grown. A related electrochromatographic technique is micellar electrokinetic capillary chromatography (MECC). This report presents a brief synopsis of research efforts during the current 3-year period. In addition to a description of analytical separations-based research, results of efforts to develop and expand spectrometric detection for the techniques is reviewed. Laser fluorometric detection schemes have been successfully advanced. Mass spectrometric research was less fruitful, largely owing to personnel limitations. A regenerable fiber optic sensor was developed that can be used to remotely monitor chemical carcinogens, etc. (DLC)

  20. Mass spectrometric characterization of a biotechnologically produced full-length mechano growth factor (MGF) relevant for doping controls.

    PubMed

    Thevis, Mario; Thomas, Andreas; Geyer, Hans; Schänzer, Wilhelm

    2014-12-01

    Since Goldspink and colleagues identified the expression of the mRNA of an insulin-like growth factor 1 (IGF-1) isoform in response to mechanical stress in 1996, substantial research into the so-called mechano growth factor and its modus operandi followed until today. Promising preclinical results were obtained by using the synthetic, 24-amino acid residues spanning peptide translated from the exons 4-6 of IGF-1Ec (which was later referred to as the mechano growth factor (MGF) peptide), particularly with regard to increased muscle myoblast proliferation. Consequently, the MGF peptide represented a promising drug candidate for the treatment of neuromuscular disorders; however, its misuse potential in sport was also identified shortly thereafter, and the substance (or class of substances) has been considered prohibited according to the regulations of the World Anti-Doping Agency (WADA) since 2005. While various MGF peptide versions have been known to sports drug testing authorities, the occurrence of a 'full-length MGF' as offered via illicit channels to athletes or athletes' managers was reported in 2014, arguably being undetectable in doping controls. An aliquot of the product was obtained and the content characterized by state-of-the-art analytical approaches including gel electrophoretic and mass spectrometric (top-down and bottom-up) sequencing approaches. Upon full characterization, its implementation into modified routine doping controls using ultrafiltration, immunoaffinity-based isolation, and nanoliquid chromatography-high resolution/high accuracy mass spectrometry was established. A protein with a monoisotopic molecular mass of 12264.9 Da and a sequence closely related to IGF-1Ec (lacking the signal- and propeptide moiety) was identified. The C-terminus was found to be modified by the elimination of the terminal lysine and a R109H substitution. With the knowledge of the compound's composition, existing doping control assays targeting peptide hormones such

  1. Mass spectrometric characterization of a prolyl hydroxylase inhibitor GSK1278863, its bishydroxylated metabolite, and its implementation into routine doping controls.

    PubMed

    Thevis, Mario; Milosovich, Susan; Licea-Perez, Hermes; Knecht, Dana; Cavalier, Tom; Schänzer, Wilhelm

    2016-08-01

    Drug candidates, which have the potential of enhancing athletic performance represent a risk of being misused in elite sport. Therefore, there is a need for early consideration by anti-doping authorities and implementation into sports drug testing programmes. The hypoxia-inducible factor (HIF) or prolyl hydroxylase inhibitor (PHI) GSK1278863 represents an advanced candidate of an emerging class of therapeutics that possess substantial potential for abuse in sport due to their capability to stimulate the biogenesis of erythrocytes and, consequently, the individual's oxygen transport capacity. A thorough characterization of such analytes by technologies predominantly used for doping control purposes and the subsequent implementation of the active drug and/or its main urinary metabolite(s) are vital for comprehensive, preventive, and efficient anti-doping work. In the present study, the HIF PHI drug candidate GSK1278863 (comprising a 6-hydroxypyrimidine-2,4-dione nucleus) and its bishydroxylated metabolite M2 (GSK2391220A) were studied regarding their mass spectrometric behaviour under electrospray ionization (ESI-MS/MS) conditions. Synthesized reference materials were used to elucidate dissociation pathways by means of quadrupole/time-of-flight high resolution/high accuracy tandem mass spectrometry, and their detection from spiked urine and elimination study urine samples under routine doping control conditions was established using liquid chromatography-electrospray ionization-tandem mass spectrometry with direct injection. Dissociation pathways to diagnostic product ions of GSK1278863 (e.g. m/z 291, 223, and 122) were proposed as substantiated by determined elemental compositions and MS(n) experiments as well as comparison to spectra of the bishydroxylated analogue M2. An analytical assay based on direct urine injection using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was developed for the simultaneous determination of GSK1278863 in

  2. Raman spectroscopic and mass spectrometric investigations of the hydrogen isotopes and isotopically labelled methane

    SciTech Connect

    Jewett, J.R., Fluor Daniel Hanford

    1997-02-24

    Suitable analytical methods must be tested and developed for monitoring the individual process steps within the fuel cycle of a fusion reactor and for tritium accountability. The utility of laser-Raman spectroscopy accompanied by mass spectrometry with an Omegatron was investigated using the analysis of all hydrogen isotopes and isotopically labeled methanes as an example. The Omegatron is useful for analyzing all hydrogen isotopes mixed with the stable helium isotopes. The application of this mass spectrometer were demonstrated by analyzing mixtures of deuterated methanes. In addition, it was employed to study the radiochemical Witzbach exchange reaction between tritium and methanes. A laser-Raman spectrometer was designed for analysis of tritium-containing gases and was built from individual components. A tritium-compatible, metal-sealed Raman cuvette having windows with good optical properties and additional means for measuring the stray light was first used successfully in this work. The Raman spectra of the hydrogen isotopes were acquired in the pure rotation mode and in the rotation-vibration mode and were used for on. The deuterated methanes were measured by Raman spectroscopy, the wavenumbers determined were assigned to the corresponding vibrations, and the wavenumbers for the rotational fine-structure were summarized in tables. The fundamental Vibrations of the deuterated methanes produced Witzbach reactions were detected and assigned. The fundamental vibrations of the molecules were obtained with Raman spectroscopy for the first time in this work. The @-Raman spectrometer assembled is well suited for the analysis of tritium- containing gases and is practical in combination with mass spectrometry using an Omegatron, for studying gases used in fusion.

  3. High-Resolution Mass Spectrometric Analysis of Oligomers Formed in Ozonation of Selected Monoterpenes

    NASA Astrophysics Data System (ADS)

    Desyaterik, Y.; Walser, M. L.; Laskin, J.; Laskin, A.; Nizkorodov, S.

    2007-12-01

    Monoterpenes constitute a significant source of the secondary organic aerosols (SOA) because of their abundant emissions from plants and high reactivity with ozone. It has been estimated that more than 50% of the total organic aerosols in specific regions are produced from monoterpene precursors. Although recent studies indicate that a significant part of secondary organic aerosols formed as a result of ozonation of monoterpenes consist of oligomeric products with high molecular weight (MW) detailed mechanism of oligomer formation is currently poorly understood. Knowledge of the molecular structure of the high MW organic products is essential for understanding of climate related properties of SOA such as hygroscopicity, CCN activity, light scattering and absorption. This work focuses on the identification of the monomeric and oligomeric chemical species present in SOA particles produced from the ozone-induced oxidation á-Pinene and d-Limonene. We take advantage of the rapidly developing tools of high-resolution mass spectrometry (HR-MS) that have the potential to analyze the aerosol particle composition without chromatographic separation techniques. High-resolution mass spectra reveal a large number of both monomeric and oligomeric products of oxidation. The combination of high resolving power (m/Δm = 60,000) and Kendrick mass defect analysis makes it possible to unambiguously determine the elemental composition for hundreds of individual compounds in SOA samples. It allows us to identify monomeric building blocks for all major oligomeric products. Positive and negative modes of HR-MS analysis provide complementary information on the composition of SOA, because less oxidized products are better observed in the positive mode while highly oxidized products tare more readily detected in the negative mode. Additional experiments using derivatization of SOA components with isotopically labeled methanol were conducted to identify compounds with aldehyde groups. An

  4. [MALDI-TOF MASS-SPECTROMETRIC ANAIYSIS OF LEPTOSPIRA SPP. USED IN SERODIAGNOSTICS OF LEPTOSPIROSIS].

    PubMed

    Zyeva, E V; Stoyanova, N A; Tokarevich, N K; Totolyan, Areg A

    2015-01-01

    Creation of a classification model of Leptospira spp. serovar model using ClinProTools 3.0 software and evaluation of use of MALDI-TOF MS as a method of quality control of reference strains of leptospira. 10 reference strains of Leptospira spp. were used in the study according to microscopic agglutination reaction from the collection of Pasteur RIEM. All the strains were cultivated for 10 days in Terskikh medium at 28 degrees C. Cell extracts were obtained by ethanol/formic acid method. α-cyano-4-hydroxycinnamic acid solution was used as a matrix. Mass-spectra were obtained in Microflex mass-spectrometer (Bruker Daltonics, Germany). External validation of the test-model was carried out using novel spectra of every reference strain during their repeated reseeding. Values of cross-validation and confirmatory ability of the optimal model, built on a genetic algorithm, was 99.14 and 100%, respectively. This model contained 11 biomarker peaks (m/z 2959, 3447, 3548, 3764, 3895, 5221, 5917, 6173, 6701, 7013, 8364) for serovar classification. Results of the external validation have shown a 100% correct classification in serovar classesin Sejroe, Ballum, Tarassovi; Copenhageni, Mozdoc, Grippotyphosa and Patoc, that indicates a high prognostic ability of the model in these classes. However, data from verification matrix have shown, that 50%.of the spectra from Canicola and Pomona serovars were classified as Patoc class, that could be associated with cross serological activity of Patoc serovar L. biflexa with pathogenic leptospirae. MALDI-TOF mass-spectrometry method combined with building and using the classification model could be a useful instrument for intra-laboratory control of leptospira reseeding.

  5. Doping control analysis of trimetazidine and characterization of major metabolites using mass spectrometric approaches.

    PubMed

    Sigmund, Gerd; Koch, Anja; Orlovius, Anne-Katrin; Guddat, Sven; Thomas, Andreas; Schänzer, Wilhelm; Thevis, Mario

    2014-01-01

    Since January 2014, the anti-anginal drug trimetazidine [1-(2,3,4-trimethoxybenzyl)-piperazine] has been classified as prohibited substance by the World Anti-Doping Agency (WADA), necessitating specific and robust detection methods in sports drug testing laboratories. In the present study, the implementation of the intact therapeutic agent into two different initial testing procedures based on gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) is reported, along with the characterization of urinary metabolites by electrospray ionization-high resolution/high accuracy (tandem) mass spectrometry. For GC-MS analyses, urine samples were subjected to liquid-liquid extraction sample preparation, while LC-MS/MS analyses were conducted by established 'dilute-and-inject' approaches. Both screening methods were validated for trimetazidine concerning specificity, limits of detection (0.5-50 ng/mL), intra-day and inter-day imprecision (<20%), and recovery (41%) in case of the GC-MS-based method. In addition, major metabolites such as the desmethylated trimetazidine and the corresponding sulfoconjugate, oxo-trimetazidine, and trimetazidine-N-oxide as identified in doping control samples were used to complement the LC-MS/MS-based assay, although intact trimetazidine was found at highest abundance of the relevant trimetazidine-related analytes in all tested sports drug testing samples. Retrospective data mining regarding doping control analyses conducted between 1999 and 2013 at the Cologne Doping Control Laboratory concerning trimetazidine revealed a considerable prevalence of the drug particularly in endurance and strength sports accounting for up to 39 findings per year.

  6. New mass-spectrometric facility for the analysis of highly radioactive samples

    SciTech Connect

    Warmack, R.J.; Landau, L.; Christie, W.H.; Carter, J.A.

    1981-01-01

    A new facility has been completed for the analysis of highly radioactive, gamma-emitting solid samples. A commercial spark-source mass spectrometer was adapted for remote handling and loading. Electrodes are prepared in a hot cell and transported to the adjacent lead-shielded source for analysis. The source was redesigned for ease of shielding, loading, and maintenance. Both solutions and residues from irradiated nuclear fuel dissolutions have been analyzed for elemental concentrations to < 1 ppM; isotopic data have also been obtained.

  7. Mass spectrometric study of the mercury isotopes in the Allende meteorite

    NASA Technical Reports Server (NTRS)

    Nier, A. O.; Schlutter, D. J.

    1986-01-01

    Isotopic abundance ratios for mercury were determined by mass spectrometry in six samples of bulk material and in one sample of chondrules from the Allende meteorite. A primary purpose of the work was to attempt to verify the anomalous ratios reported for Hg-196/Hg-202 by neutron activation. Measurements were made on the mercury released at temperatures of 250, 450, 600 C, and in some cases, higher temperatures. The precision of the measurements was such that if an anomaly of the magnitude reported exists, it should have been seen. The isotopic abundance ratios for the other mercury isotopes were also measured. Within the errors of measurement these agreed with normal terrestrial values.

  8. Thermodynamic properties of spinel MgAl2O4: A mass spectrometric study

    NASA Astrophysics Data System (ADS)

    Shornikov, S. I.

    2017-02-01

    The activities of oxides in stoichiometric spinel MgAl2O4 in the temperature range 1851-2298 K were determined from the data obtained by the Knudsen effusion mass spectrometry. The resulting Gibbs energies of spinel formation from simple oxides, the enthalpies and entropies of spinel formation from simple oxides (-12.02 ± 1.14 kJ/mol and 5.03 ± 0.56 J/(mol K), respectively), and the spinel melting enthalpy (55.81 ± 4.62 kJ/mol) satisfactorily agree with the available thermodynamic data.

  9. Mass spectrometric study of the evaporation of MgAl2O4 spinel

    NASA Astrophysics Data System (ADS)

    Shornikov, S. I.

    2017-01-01

    The evaporation of MgAl2O4 spinel is studied via high-temperature Knudsen effusion mass spectrometry in the temperature range of 1850-2250 K. In the gas phase, molecular components typical of the simple oxides in the spinel and traces of gaseous complex oxide MgAlO are identified above the samples. The resulting values of the partial vapor pressures of the molecular components contained in the gas phase over the spinel are compared with those corresponding to simple oxides for the first time.

  10. Formation and thermodynamics of gaseous germanium and tin vanadates: a mass spectrometric and quantum chemical study.

    PubMed

    Shugurov, S M; Panin, A I; Lopatin, S I; Emelyanova, K A

    2015-06-07

    The stabilities of gaseous germanium and tin vanadates were confirmed by high temperature mass spectrometry, and its structures were determined by quantum chemical calculations. A number of gas-phase reactions involving these gaseous salts were studied. On the basis of the equilibrium constants, the standard formation enthalpies of gaseous GeV2O6 (-1520 ± 42 kJ mol(-1)) and SnV2O6 (-1520 ± 43 kJ mol(-1)) were determined at a temperature of 298 K.

  11. A Mass-Spectrometric Investigation of the Chemistry of Advanced Composite and Double Base Propellants.

    DTIC Science & Technology

    1978-08-01

    reaction can be identified if they effuse into the molecular beam to the mass spectrometer. Also, intermediate species having a short lifetime (on the...ammonium perchlorate decomposition. The reaction between Pb 3 0 4 and carbon to produce the lead atom along with CO is extremely exothermic. This... reaction , Pb30 4 (c) + 4C(s) = 3Pb(l) + 4CO(g), has a free energy of -446.8 kJ at 1000 K. The lead compounds identified included PbCl, PbCIO and PbNO 2

  12. Gas chromatographic-mass spectrometric analysis of creosotes extracted from wooden sleepers installed in playgrounds

    SciTech Connect

    Rotard, W.; Mailahn, W.

    1987-01-01

    In order to evaluate their hygienic risk, wood samples from sleepers (railroad cross ties) impregnated with coal tar creosote were taken from playgrounds and investigated for hazardous compounds. The samples were extracted with ether, and acid-base-neutral separations were made on the creosote extracts. Water-soluble compounds were also isolated. All the fractions were investigated by capillary gas chromatography-mass spectrometry. Besides phenols in the acidic fractions and N-heterocyclic polynuclear aromatic hydrocarbons (PAH) in the basic fractions, high amounts of neutral PAH and also, in several samples high levels of carcinogenic and cocarcinogenic PAH were determined.

  13. New FORTRAN computer programs to acquire and process isotopic mass spectrometric data: Operator`s manual

    SciTech Connect

    Smith, D.H.; McKown, H.S.

    1993-09-01

    This TM is one of a pair that describes ORNL-developed software for acquisition and processing of isotope ratio mass spectral data. This TM is directed at the laboratory analyst. No technical knowledge of the programs and programming is required. It describes how to create and edit files, how to acquire and process data, and how to set up files to obtain the desired results. The aim of this TM is to serve as a utilitarian instruction manual, a {open_quotes}how to{close_quotes} approach rather than a {open_quotes}why?{close_quotes}

  14. Ion Exchange Chromatography and Mass Spectrometric Methods for Analysis of Cadmium-Phytochelatin (II) Complexes

    PubMed Central

    Merlos Rodrigo, Miguel Angel; Cernei, Natalia; Kominkova, Marketa; Zitka, Ondrej; Beklova, Miroslava; Zehnalek, Josef; Kizek, Rene; Adam, Vojtech

    2013-01-01

    In this study, in vitro formed Cd-phytochelatin (PC2) complexes were characterized using ion exchange chromatography (IEC) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The ratio of both studied compounds as well as experimental conditions were optimized. The highest yield of the complex was observed under an applied concentration of 100 µg·mL−1 PC2 and 100 µg·mL−1 of CdCl2. The data obtained show that IEC in combination with MALDI-TOF is a reliable and fast method for the determination of these complexes. PMID:23538727

  15. Ion exchange chromatography and mass spectrometric methods for analysis of cadmium-phytochelatin (II) complexes.

    PubMed

    Rodrigo, Miguel Angel Merlos; Cernei, Natalia; Kominkova, Marketa; Zitka, Ondrej; Beklova, Miroslava; Zehnalek, Josef; Kizek, Rene; Adam, Vojtech

    2013-03-28

    In this study, in vitro formed Cd-phytochelatin (PC2) complexes were characterized using ion exchange chromatography (IEC) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The ratio of both studied compounds as well as experimental conditions were optimized. The highest yield of the complex was observed under an applied concentration of 100 µg·mL(-1) PC2 and 100 µg·mL(-1) of CdCl2. The data obtained show that IEC in combination with MALDI-TOF is a reliable and fast method for the determination of these complexes.

  16. Mass spectrometric analysis of chemical warfare agents and their degradation products in soil and synthetic samples.

    PubMed

    D'Agostino, Paul A; Hancock, James R; Chenier, Claude L

    2003-01-01

    A packed capillary liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) method was developed for the identification of chemical warfare agents, their degradation products and related compounds in synthetic tabun samples and in soil samples collected from a former mustard storage site. A number of organophosphorus and organosulfur compounds that had not been previously characterized were identified, based on acquired high-resolution ESI-MS data. At lower sampling cone voltages, the ESI mass spectra were dominated by protonated, sodiated and protonated acetonitrile adducts and/or their dimers that could be used to confirm the molecular mass of each compound. Structural information was obtained by inducing product ion formation in the ESI interface at higher sampling cone voltages. Representative ESI-MS mass spectra for previously uncharacterized compounds were incorporated into a database as part of an on-going effort in chemical warfare agent detection and identification. The same samples were also analyzed by capillary column gas chromatography (GC)-MS in order to compare an established method with LC-ESI-MS for chemical warfare agent identification. Analysis times and full-scanning sensitivities were similar for both methods, with differences being associated with sample matrix, ease of ionization and compound volatility. GC-MS would be preferred for organic extracts and must be used for the determination of mustard and relatively non-polar organosulfur degradation products, including 1,4- thioxane and 1,4-dithiane, as these compounds do not ionize during ESI-MS. Diols, formed following hydrolysis of mustard and longer-chain sulfur vesicants, may be analyzed using both methods with LC-ESI-MS providing improved chromatographic peak shape. Aqueous samples and extracts would, typically, be analyzed by LC-ESI-MS, since these analyses may be conducted directly without the need for additional sample handling and/or derivatization associated with

  17. Gas chromatographic-mass spectrometric assay for 6-hydroxymelatonin sulfate and 6-hydroxymelatonin glucuronide in urine

    SciTech Connect

    Francis, P.L.; Leone, A.M.; Young, I.M.; Stovell, P.; Silman, R.E.

    1987-04-01

    Circulating melatonin is hydroxylated to 6-hydroxymelatonin and excreted in urine as the sulfate and glucuronide conjugates. We extracted these two compounds from urine by using octadecylsilane-bonded silica cartridges to eliminate most of the urea and electrolytes, and silica cartridges to separate the sulfate and glucuronide conjugates. After hydrolyzing the separated conjugates enzymically, we determined the free hydroxymelatonin by gas chromatography-mass spectrometry. Though recoveries were low and variable, we were able to quantify the analyte in the original sample by adding deuterated sulfate and glucuronide conjugates to the urines before extraction.

  18. Mass spectrometric analysis of putative capa-gene products in Musca domestica and Neobellieria bullata.

    PubMed

    Predel, Reinhard; Russell, William K; Tichy, Shane E; Russell, David H; Nachman, Ronald J

    2003-10-01

    Neuropeptides of the capa-gene are typical of the abdominal neurosecretory system of insects. In this study, we investigated these peptides in two widely distributed and large pest flies, namely Musca domestica and Neobellieria bullata. Using a combination of MALDI-TOF and ESI-QTOF mass spectrometry, periviscerokinins and a pyrokinin were analyzed from single perisympathetic organ preparations. The species-specific peptide sequences differ remarkably between the related dipteran species. These differences could make it possible to develop peptide-analogs with group- or species-specific efficacy.

  19. Going beyond electrospray: mass spectrometric studies of chemical reactions in and on liquids

    PubMed Central

    Ingram, Andrew J.; Boeser, Cornelia L.

    2016-01-01

    There has been a burst in the number and variety of available ionization techniques to use mass spectrometry to monitor chemical reactions in and on liquids. Chemists have gained the capability to access chemistry at unprecedented timescales, and monitor reactions and detect intermediates under almost any set of conditions. Herein, recently developed ionization techniques that facilitate mechanistic studies of chemical processes are reviewed. This is followed by a discussion of our perspective on the judicious application of these and similar techniques in order to study reaction mechanisms. PMID:28757996

  20. Mass spectrometric base composition profiling: Implications for forensic mtDNA databasing.

    PubMed

    Eduardoff, Mayra; Huber, Gabriela; Bayer, Birgit; Schmid, Dagmar; Anslinger, Katja; Göbel, Tanja; Zimmermann, Bettina; Schneider, Peter M; Röck, Alexander W; Parson, Walther

    2013-12-01

    In forensic genetics mitochondrial DNA (mtDNA) is usually analyzed by direct Sanger-type sequencing (STS). This method is known to be laborious and sometimes prone to human error. Alternative methods have been proposed that lead to faster results. Among these are methods that involve mass-spectrometry resulting in base composition profiles that are, by definition, less informative than the full nucleotide sequence. Here, we applied a highly automated electrospray ionization mass spectrometry (ESI-MS) system (PLEX-ID) to an mtDNA population study to compare its performance with respect to throughput and concordance to STS. We found that the loss of information power was relatively low compared to the gain in speed and analytical standardization. The detection of point and length heteroplasmy turned out to be roughly comparable between the technologies with some individual differences related to the processes. We confirm that ESI-MS provides a valuable platform for analyzing mtDNA variation that can also be applied in the forensic context.

  1. Comparison of analysis of vitamin D3 in foods using ultraviolet and mass spectrometric detection.

    PubMed

    Byrdwell, William C

    2009-03-25

    A method for analysis of vitamin D(3) in commonly fortified foods and in fish, which contains endogenous vitamin D(3), was developed by combining the best aspects of two official methods. The ethyl ether/petroleum ether extraction procedure from AOAC 992.26 was combined with the chromatographic separation and use of an internal standard (vitamin D(2)) from AOAC 2002.05 to produce a method that was applicable to a variety of food samples. Results for skim milk, orange juice, breakfast cereal, salmon, a diluted USP reference standard (vitamin D(3) in peanut oil), and processed cheese are presented. Results indicated that UV detection was adequate in most cases, but the absence of interfering species must be determined in each food by mass spectrometry. Selected ion monitoring (SIM) atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) was shown to produce statistically indistinguishable results compared to UV detection for the skim milk, orange juice, multigrain cereal, and salmon samples. The processed cheese exhibited interferences that precluded quantification of vitamin D(3) by UV detection, and therefore, only SIM APCI-MS data for that sample were valid.

  2. Liquid chromatographic-tandem mass spectrometric method for the quantitation of sildenafil in human plasma.

    PubMed

    Wang, Yingwu; Wang, Jiang; Cui, Yimin; Fawcett, J Paul; Gu, Jingkai

    2005-12-15

    A method to determine sildenafil in human plasma involving liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed. Sildenafil and the internal standard (I.S.), diazepam, are extracted from human plasma with ether-dichloromethane (3:2, v/v) at basic pH and analyzed by reversed-phase high-performance liquid chromatography (HPLC) using methanol-10mM ammonium acetate pH 7.0 (85:15, v/v) as the mobile phase. Detection by electrospray positive ionization mass spectrometry in the multiple-reaction monitoring mode was linear over the concentration range 0.125-40.0 ng/ml. Intra- and inter-day precision of the assay at four concentrations within this range were 2.5-8.0%. The method was used to evaluate plasma concentration-time profiles in healthy volunteers given an oral dose of 20mg sildenafil as a combination tablet also containing apomorphine.

  3. Mass spectrometric investigation of the vaporization of sodium and potassium chromates: Preliminary results

    NASA Technical Reports Server (NTRS)

    Stearns, C. A.; Kohl, F. J.; Miller, R. A.; Fryburg, G. C.

    1979-01-01

    Knudsen cell mass spectrometry was used to study the vaporization of sodium and potassium chromates. For both salts, the vaporization proceeds predominately by the reactions M2CrO4(c)=2M(g)+5/4O2(g)+1/2 Cr203(s) and M2CrO4(c)=M2CrO4(g) where M = Na or K. The distribution of the ions M(+), O2(+) and M2CrO4(+) in the measured mass spectrum was found to depend on the material used for the Knudsen cell, even for materials such as platinum and gold. In the case of sodium chromate, the decomposition reaction appears to be less important than the molecular vaporization reaction. A preliminary value of 72 kcal/mole at 1141 K was measured for the heat of the molecular vaporization reaction for sodium chromate. In the case of potassium chromate, it has not been possible to conclude which mode of vaporization dominates. For potassium chromate a value of 101 kcal/mole at 1173 K was obtained for the heat of the molecular vaporization reaction.

  4. Revisiting the quantitative features of surface-assisted laser desorption/ionization mass spectrometric analysis.

    PubMed

    Wu, Ching-Yi; Lee, Kai-Chieh; Kuo, Yen-Ling; Chen, Yu-Chie

    2016-10-28

    Surface-assisted laser desorption/ionization (SALDI) coupled with mass spectrometry (MS) is frequently used to analyse small organics owing to its clean background. Inorganic materials can be used as energy absorbers and the transfer medium to facilitate the desorption/ionization of analytes; thus, they are used as SALDI-assisting materials. Many studies have demonstrated the usefulness of SALDI-MS in quantitative analysis of small organics. However, some characteristics occurring in SALDI-MS require certain attention to ensure the reliability of the quantitative analysis results. The appearance of a coffee-ring effect in SALDI sample preparation is the primary factor that can affect quantitative SALDI-MS analysis results. However, to the best of our knowledge, there are no reports relating to quantitative SALDI-MS analysis that discuss or consider this effect. In this study, the coffee-ring effect is discussed using nanoparticles and nanostructured substrates as SALDI-assisting materials to show how this effect influences SALDI-MS analysis results. Potential solutions for overcoming the existing problems are also suggested.This article is part of the themed issue 'Quantitative mass spectrometry'.

  5. Mass Spectrometric Approaches to the Identification of Potential Ingredients in Cigarette Smoke Causing Cytotoxicity.

    PubMed

    Horiyama, Shizuyo; Kunitomo, Masaru; Yoshikawa, Noriko; Nakamura, Kazuki

    2016-01-01

    Cigarette smoke contains many harmful chemicals that contribute to the pathogenesis of smoking-related diseases such as chronic obstructive pulmonary disease, cancer, and cardiovascular disease. Many studies have been done to identify cytotoxic chemicals in cigarette smoke and elucidate the onset of the above-mentioned diseases caused by smoking. However, definitive mechanisms for cigarette smoke toxicity remain unknown. As candidates for cytotoxic chemicals, we have recently found methyl vinyl ketone (MVK) and acetic anhydride in nicotine/tar-free cigarette smoke extract (CSE) using L-tyrosine (Tyr), an amino acid with highly reactive hydroxyl group. The presence of MVK and acetic anhydride in CSE was confirmed by gas chromatography-mass spectrometry (GC/MS). We also found new reaction products formed in B16-BL6 mouse melanoma (B16-BL6) cells treated with CSE using LC/MS. These were identified as glutathione (GSH) conjugates of α,β-unsaturated carbonyl compounds, MVK, crotonaldehyde (CA), and acrolein (ACR), by the mass value and product ion spectra of these new products. ACR and MVK are type-2 alkenes, which are well known as electron acceptors and form Michael-type adducts to nucleophilic side chain of amino acids on peptides. These α,β-unsaturated carbonyl compounds may have a key role in CSE-induced cell death.

  6. Mass spectrometric helium analysis of solid and gas samples from cold-fusion type experiments

    SciTech Connect

    Oliver, B.M.

    1995-12-01

    A custom mass spectrometer system, operating in static mode, has been used to measure helium in both solid and gas samples front cold-fusion type experiments. The mass spectrometer is a 2-in. Radius, 60{degrees}, permanent angle magnet instrument with a single electron-multiplier collecting. Depending on the absolute levels of helium expected, the analysis are conducted by isotope dilution or by measuring absolute collector values. Solid samples are vaporized to ensure complete helium release. Prior to analysis, the fraction of sample gas to be analyzed is exposed to a series of physical and chemical getters, including room temperature Zr-Al alloy (SAES type 101) and liquid-nitrogen cooled activated charcoal. This is done to remove active gases and hydrogen isotopes which could interfere with the helium determinations. Generally, the analysis protocol is to analyze an equal or greater number of {open_quotes}controls{close_quotes} along with the samples to accurately characterize system background and reproducibility. Absolute sensitivity for the system is approximately 1 x 10{sup 9} atoms. Absolute accuracy is 1% or better for helium levels > 10{sup 11} atoms. With few exceptions, helium analysis of solid samples front cold fusion type experiments have yielded no excess helium above usual system background. A few samples have shown helium levels in the low 10{sup 9} atom range, and some gas samples have shown {sup 4}He levels up to several hundred ppm.

  7. Integrated Microfluidic Aptasensor for Mass Spectrometric Detection of Vasopressin in Human Plasma Ultrafiltrate.

    PubMed

    Yang, J; Zhu, J; Pei, R; Oliver, J A; Landry, D W; Stojanovic, M N; Lin, Q

    2016-07-14

    We present a microfluidic aptamer-based biosensor for detection of low-molecular-weight biomarkers in patient samples. Using a microfluidic device that integrates aptamer-based specific analyte extraction, isocratic elution, and detection by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, we demonstrate rapid, sensitive and label-free detection of arginine vasopressin (AVP) in human plasma ultrafiltrate. AVP molecules in complex matrices are specifically captured by an aptamer that is immobilized on microbeads via affinity binding in a microchamber. After the removal of unbound, contaminating molecules through washing, aptamer-AVP complexes are thermally disrupted via on-chip temperature control. Released AVP molecules are eluted with purified water and transferred to a separate microchamber, and deposited onto a single spot on a MALDI plate via repeated, piezoelectrically actuated ejection, which enriches AVP molecules over the spot area. This integrated on-chip sample processing enables the quantitative detection of low-abundance AVP by MALDI-TOF mass spectrometry in a rapid and label-free manner. Our experimental results show the detection of AVP in human plasma ultrafiltrate as low as physiologically relevant picomolar concentrations via aptamer-based selective preconcentration, demonstrating the potential of our approach as a rapid (~ 1hr), sensitive clinical AVP assay.

  8. Process and Formulation Effects on Protein Structure in Lyophilized Solids using Mass Spectrometric Methods

    PubMed Central

    Iyer, Lavanya K.; Sacha, Gregory A.; Moorthy, Balakrishnan S.; Nail, Steven L.; Topp, Elizabeth M.

    2016-01-01

    Myoglobin (Mb) was lyophilized in the absence (Mb-A) and presence (Mb-B) of sucrose in a pilot-scale lyophilizer with or without controlled ice nucleation. Cake morphology was characterized using scanning electron microscopy (SEM) and changes in protein structure were monitored using solid-state Fourier-transform infrared spectroscopy (ssFTIR), solid-state hydrogen-deuterium exchange-mass spectrometry (ssHDX-MS) and solid-state photolytic labeling-mass spectrometry (ssPL-MS). The results showed greater variability in nucleation temperature and irregular cake structure for formulations lyophilized without controlled nucleation. Controlled nucleation resulted in nucleation at ~ −5 °C and uniform cake structure. Formulations containing sucrose showed better retention of protein structure by all measures than formulations without sucrose. Samples lyophilized with and without controlled nucleation were similar by most measures of protein structure. However, ssPL-MS showed the greatest pLeu incorporation and more labeled regions for Mb-B lyophilized with controlled nucleation. The data support the use of ssHDX-MS and ssPL-MS to study formulation and process-induced conformational changes in lyophilized proteins. PMID:27044943

  9. Mass spectrometric characterisation of proteins in rennet and in chymosin-based milk-clotting preparations.

    PubMed

    Lilla, S; Caira, S; Ferranti, P; Addeo, F

    2001-01-01

    The protein composition of natural rennet and of chromatographic and crystalline chymosin preparations has been defined by on-line reverse-phase high performance liquid chromatography/electrospray ionisation mass spectrometry (RP-HPLC/ESI-MS) and by tandem mass spectrometry (MS/MS). Natural rennet was found to consist of six chymosin species, corresponding to chymosin A and B genetic variants, each of which comprised a mixture of two other forms differing at theN-terminal end, with one being three residues longer, and the other two residues shorter, than the mature chymosin. Two main tissue proteins were also identified as lysozyme (isozyme 2 plus a novel isozyme labelled 4) and bovine serum albumin. In addition to the proteins, chymosin fragments 247-323 and 288-323 were consistently present in natural rennet. Conversely, chromatographic and crystalline chymosin preparations lacked bovine serum albumin and/or lysozyme, although they contained the same six chymosin species as natural rennet. Since these tissue-specific contaminating proteins each possess specific functions in terms of stabilising enzyme solutions and protecting proteins from proteolytic enzymes, oxidising agents and bacterial proliferation, the rennet may be considered as a functional enzyme preparation that is effectively and naturally adapted to the purposes of cheesemaking. In practice, the highly complex protein composition inherent to natural rennet provided the possibility to differentiate the natural product from other bovine chymosin-based milk-clotting preparations examined in this work. Copyright 2001 John Wiley & Sons, Ltd.

  10. Mass spectrometric base composition profiling: Implications for forensic mtDNA databasing☆

    PubMed Central

    Eduardoff, Mayra; Huber, Gabriela; Bayer, Birgit; Schmid, Dagmar; Anslinger, Katja; Göbel, Tanja; Zimmermann, Bettina; Schneider, Peter M.; Röck, Alexander W.; Parson, Walther

    2013-01-01

    In forensic genetics mitochondrial DNA (mtDNA) is usually analyzed by direct Sanger-type sequencing (STS). This method is known to be laborious and sometimes prone to human error. Alternative methods have been proposed that lead to faster results. Among these are methods that involve mass-spectrometry resulting in base composition profiles that are, by definition, less informative than the full nucleotide sequence. Here, we applied a highly automated electrospray ionization mass spectrometry (ESI-MS) system (PLEX-ID) to an mtDNA population study to compare its performance with respect to throughput and concordance to STS. We found that the loss of information power was relatively low compared to the gain in speed and analytical standardization. The detection of point and length heteroplasmy turned out to be roughly comparable between the technologies with some individual differences related to the processes. We confirm that ESI-MS provides a valuable platform for analyzing mtDNA variation that can also be applied in the forensic context. PMID:24054029

  11. Electrophoretic Separation-Mass Spectrometric Detection on Polymer Microchip Directly Integrated with a Nanospray Tip

    NASA Astrophysics Data System (ADS)

    Kitagawa, Fumihiko; Shinohara, Hidetoshi; Mizuno, Jun; Otsuka, Koji; Shoji, Shuichi

    We fabricated a polymer chip for microchip electrophoresis-mass spectrometry (MCE—MS). As a substrate material, cycloolefin polymer (COP) was selected due to its high chemical durability and easy metallization for the electrode. A COP microchip with a conventional cross-type channel configuration for the MCE separation was fabricated by hot embossing. After bonding with a rid substrate, a nano electrospray ionization (nano-ESI) tip structure for MS detection was machined directly at the opening of the separation channel end. A gold electrode to keep the electric contact for ESI was deposited around the nanospray tip by electron beam evaporation. When the voltage of 3.0 and 2.0 kV was applied to the inlet and the ESI electrode, respectively, the formation of Taylor cone and stable electrospray were observed at the channel opening. In infusion analysis of caffeine, the MS spectrum with parent mass number of 195, which accords with that of the protonated caffeine, was successfully obtained in the positive mode. Furthermore, the MCE separation and ESI-MS detection of caffeine and arginine was also successfully achieved with resolution of 1.0. Therefore, these results demonstrated that the fabricated microchip integrated with the nano-ESI tip can be employed as the MCE—ESI-MS device.

  12. Applications of free-jet, molecular beam, mass spectrometric sampling: Proceedings

    SciTech Connect

    Milne, T.

    1995-03-01

    Over the past 35 years, the study of die behavior and uses of free-jet expansions for laboratory experiments has greatly expanded and matured. Not the least of these uses of free-jet expansions, is that of extractive sampling from high temperature, reactive systems. The conversion of the free-jet expanded gases to molecular flow for direct introduction into the ion source of a mass spectrometer offers several advantages, to be illustrated in these pages. Two meetings on this subject were held in 1965 and 1972 in Missouri, sponsored by the Office of Naval Research and Midwest Research Institute. At these meetings rarefied gas dynamicists came together with scientists using free-jet sampling for analytical purposes. After much too long a time, this workshop was convened to bring together modem practitioners of FJMBS (Free-jet, Molecular-beam, mass spectrometry) and long time students of the free-jet process itself, to assess the current state of the art and to forge a community that can foster the development of this novel analytical approach. This proceedings is comprised of 38 individually submitted papers. Individual papers are indexed separately on the Energy Data Base.

  13. The effect of metal ions on Staphylococcus aureus revealed by biochemical and mass spectrometric analyses.

    PubMed

    Chudobova, Dagmar; Dostalova, Simona; Ruttkay-Nedecky, Branislav; Guran, Roman; Rodrigo, Miguel Angel Merlos; Tmejova, Katerina; Krizkova, Sona; Zitka, Ondrej; Adam, Vojtech; Kizek, Rene

    2015-01-01

    In this study, we focused on the effect of heavy metal ions in resistant strains of gram-positive bacteria Staphylococcus aureus using biochemical methods and mass spectrometry. Five nitrate solutions of heavy metals (Ag(+), Cu(2+), Cd(2+), Zn(2+) and Pb(2+)) were used to create S. aureus resistant strains. Biochemical changes of resistant strains in comparison with the non-resistant control strain of S. aureus were observed by microbiological (measuring - growth curves and inhibition zones) and spectrophotometric methods (antioxidant activity and alaninaminotransferase, aspartateaminotransferase, alkaline phosphatase, γ-glutamyltransferase activities). Mass spectrometry was employed for the qualitative analysis of the samples (changes in S. aureus protein composition) and for the identification of the strains database MALDI Biotyper was employed. Alterations, in terms of biochemical properties and protein composition, were observed in resistant strains compared to non-resistant control strain. Our results describe the possible option for the analysis of S. aureus resistant strains and may thus serve as a support for monitoring of changes in genetic information caused by the forming of resistance to heavy metals.

  14. Application of a Mass Spectrometric Approach to Detect the Presence of Fatty Acid Biosynthetic Phosphopeptides.

    PubMed

    Lau, Benjamin Yii Chung; Clerens, Stefan; Morton, James D; Dyer, Jolon M; Deb-Choudhury, Santanu; Ramli, Umi Salamah

    2016-04-01

    The details of plant lipid metabolism are relatively well known but the regulation of fatty acid production at the protein level is still not understood. Hence this study explores the importance of phosphorylation as a mechanism to control the activity of fatty acid biosynthetic enzymes using low and high oleic acid mesocarps of oil palm fruit (Elaeis guineensis variety of Tenera). Adaptation of neutral loss-triggered tandem mass spectrometry and selected reaction monitoring to detect the neutral loss of phosphoric acid successfully found several phosphoamino acid-containing peptides. These peptides corresponded to the peptides from acetyl-CoA carboxylase and 3-enoyl-acyl carrier protein reductase as identified by their precursor ion masses. These findings suggest that these enzymes were phosphorylated at 20th week after anthesis. Phosphorylation could have reduce their activities towards the end of fatty acid biosynthesis at ripening stage. Implication of phosphorylation in the regulation of fatty acid biosynthesis at protein level has never been reported.

  15. Electrospray ionization mass spectrometric studies on the characteristic fragmentation of Asp/cyclen conjugates.

    PubMed

    Ma, Chunying; Li, Chao; Luan, Xingrong; Zhang, Jin; Qiao, Renzhong; Zhao, Yufen

    2014-03-30

    Differentiation and structural characterization of Asp/cyclen conjugates by electrospray ionization tandem mass spectrometry (ESI-MS(n)) are significantly important for their biomedical application. Hence, the present study is conducted. The fragmentations of Asp/cyclen conjugates generated by positive ion mode electrospray ionization were examined here by low-energy collision-induced dissociation (CID). ESI-MS(n) spectra of cyclen were acquired to confirm cyclen contraction products derived from the studied compounds. The fragments derived from the Asp/cyclen conjugates were proved by deuterium-exchange experiments. Asp/cyclen conjugates displayed characteristic dissociation pathways, including cleavages of amide bonds, loss of NH3 and cyclen contraction pathways. It was observed that cleavages of C-terminal amide bonds generated b2 and b2  + H2O ions from the protonated CyclenAspAspAsp and a b1  + H2O ion from the protonated CyclenAspAsp. In addition, various cyclen contraction products were also observed. In ESI-MS(n) spectra of studied compounds, fragments of bn-1  + H2O or cyclic anhydride were generated due to facile mobilization of C-terminal or side-chain COOH protons. In addition, the cyclen contraction products were detected. These results might provide sufficient information for the identification of Asp/cyclen conjugates by mass spectrometry. Copyright © 2014 John Wiley & Sons, Ltd.

  16. Tandem mass spectrometric analysis of a complex triterpene saponin mixture of Chenopodium quinoa.

    PubMed

    Madl, Tobias; Sterk, Heinz; Mittelbach, Martin; Rechberger, Gerald N

    2006-06-01

    A nano-HPLC electrospray ionization multi-stage tandem mass spectrometry (nLC-ESI-MS/MS) approach was applied to a complex crude triterpene saponin extract of Chenopodium quinoa seed coats. In ESI-MS/MS spectra of triterpene saponins, characteristic fragmentation reactions are observed and allow the determination of aglycones, saccharide sequences, compositions, and branching. Fragmentation of aglycones provided further structural information. The chemical complexity of the mixture was resolved by a complete profiling. Eighty-seven triterpene saponins comprising 19 reported and 68 novel components were identified and studied by MS. In addition to four reported, five novel triterpene aglycones were detected and characterized according to their fragmentation reactions in ESI-MS/MS and electron ionization mass spectrometry (EI-MS). As a novelty fragmentation pathways were proposed and analyzed based upon quantum chemical calculations using a hybrid Hartree-Fock density functional method. Accuracy of the assignment procedure was proven by isolation and structure determination of a novel compound. As the relative distribution and composition of saponins varies between different cultivars and soils, the presented strategy allows a rapid and complete analysis of Chenopodium quinoa saponin distribution and composition, and is particularly suitable for quality control and screening of extracts designated for pharmaceutical, agricultural, and industrial applications.

  17. Gas chromatographic-mass spectrometric analysis of chemical volatiles in buffalo (Bubalus bubalis) urine.

    PubMed

    Barman, Purabi; Yadav, M C; Kumar, H; Meur, S K; Ghosh, S K

    2013-10-01

    Isolation of active fraction and characterization of chemosignals from urine have been attempted in several mammalian species in the recent years. The objective of this study was to identify the urinary volatiles across various reproductive stages of buffalo cow, namely, estrus, diestrus, and pregnancy, and in bull, by chemical extraction followed by gas chromatography-linked mass spectrometry (GC-MS). Urine samples were collected from six buffalo cows at two different phases of estrous cycle, namely, estrus and diestrus. Besides, urinary samples were collected from five pregnant buffalo cows (60-75 days after artificial insemination (AI)) and six adult bulls. Thin-layer chromatography was performed as a preliminary test for qualitative comparison of different compounds extracted by organic solvents. Identification of the urinary compounds was carried out in a gas chromatograph (Perkin Elmer, Autosystem XL) linked to a mass spectrometer (Turbomass). The results of GC-MS analysis indicated the presence of 21 compounds with varying molecular weights and retention time, which were further categorized as diestrus-specific, pregnancy-specific, and bull-specific urinary compounds. No compound, however, could be identified as estrus-specific. We concluded that qualitative differences do exist in estrus, diestrus, and pregnant buffalo cow urine and in bull urine, as evidenced by GC-MS. Copyright © 2013 Elsevier Inc. All rights reserved.

  18. Nanopatterned Extracellular Matrices Enable Cell-Based Assays with a Mass Spectrometric Readout.

    PubMed

    Cabezas, Maria D; Mirkin, Chad A; Mrksich, Milan

    2017-03-08

    Cell-based assays are finding wider use in evaluating compounds in primary screens for drug development, yet it is still challenging to measure enzymatic activities as an end point in a cell-based assay. This paper reports a strategy that combines state-of-the-art cantilever free polymer pen lithography (PPL) with self-assembled monolayer laser desorption-ionization (SAMDI) mass spectrometry to guide cell localization and measure cellular enzymatic activities. Experiments are conducted with a 384 spot array, in which each spot is composed of ∼400 nanoarrays and each array has a 10 × 10 arrangement of 750 nm features that present extracellular matrix (ECM) proteins surrounded by an immobilized phosphopeptide. Cells attach to the individual nanoarrays, where they can be cultured and treated with small molecules, after which the media is removed and the cells are lysed. Phosphatase enzymes in the proximal lysate can then act on the immobilized phosphopeptide substrate to convert it to the dephosphorylated form. After the lysate is removed, the array is analyzed by SAMDI mass spectrometry to identify the extent of dephosphorylation and, therefore, the amount of enzyme activity in the cell. This novel approach of using nanopatterning to mediate cell adhesion and SAMDI to record enzyme activities in the proximal lysate will enable a broad range of cellular assays for applications in drug discovery and research not possible with conventional strategies.

  19. Quantitation of tetrahydrocannabinol in hair using immunoassay and liquid chromatography with tandem mass spectrometric detection.

    PubMed

    Coulter, Cynthia; Taruc, Margaux; Tuyay, James; Moore, Christine

    2009-05-01

    A quantitative analytical procedure for the determination of Delta(9)-tetrahydrocannabinol (THC) in hair has been developed and validated using liquid chromatography with tandem mass spectral detection (LC-MS/MS). Specimens that were determined as containing cannabinoids following immunoassay testing were quantified using solid-phase extraction followed by liquid chromatographic separation and tandem mass spectral detection in positive electrospray ionization mode. For confirmation, two transitions were monitored and one ratio determined. Samples being reported as positive were required to have both transitions present, the ratio of quantifying transition to qualifying transition being within 20% of that determined from known calibration standards. The limit of quantitation and the limit of detection was 10 pg/mg. The percentage recovery of the THC from hair at 20 pg/mg was 56% and a matrix effect of the hair showed an ion suppression percentage of -51%. The immunochemical screening method was performed following a rapid aqueous extraction, requiring only 10 mg of hair; the confirmatory procedure required 20 mg of hair. The methods were applied to proficiency specimens from the Society of Hair Testing, which had been received in August 2008.

  20. Sequence microheterogeneity of parvalbumin pI 5.0 of pike: a mass spectrometric study.

    PubMed

    Permyakov, Sergei E; Karnoup, Anton S; Bakunts, Anush G; Permyakov, Eugene A

    2009-01-01

    Parvalbumin (PA) is a muscle and neuronal calcium-binding protein, the major fish and frog allergen. Its characteristic feature is the presence of multiple isoforms with significantly different amino acid sequences. Here we show that the major isoform of northern pike muscle PA (pI 5.0, alpha-PA) exhibits microheterogeneity of amino acid sequence. ESI Q-TOF mass-spectrometry (MS) analysis of alpha-PA sample showed the presence of two components with mass difference of 71 Da. Analysis of tryptic and endoproteinase Asp-N digests of alpha-PA by MALDI-TOF MS revealed peptides, corresponding to two different amino acid sequences. The sequence differences between variant proteins are limited to AB-domain and include substitutions K27A and L31K, and an extra Leu residue between K11 and K12. Since the affected residues comprise a cluster on the surface of PA, an involvement of the identified region into target recognition is suggested. The substitutions at positions 27 and 31 are located in the region of previously identified epitopes of parvalbumin relevant for PA-specific IgE and IgG binding, which suggests different immunoactivities of the variants. The found microheterogeneity of PA is suggested to be of importance for physiological adaptation of the propulsive musculature to developmental and/or environmental requirements and may contribute to PA allergenicity.

  1. Gas chromatographic-mass spectrometric determination of plasma saturated fatty acids using pentafluorophenyldimethylsilyl derivatization.

    PubMed

    Yang, Y J; Choi, M H; Paik, M J; Yoon, H R; Chung, B C

    2000-05-26

    An improved method for the detection of 11 saturated fatty acids (SFAs) including C12:0-C26:0 (even numbers only), C17:0, C19:0 and C23:0 in human plasma by gas chromatography-mass spectrometry (GC-MS) with a stable isotope internal standard as d3-stearic acid is described. This procedure was based on acidic treatment, liquid-liquid extraction, and chemical derivatization prior to instrumental analysis. Eleven pentafluorophenyldimethylsilyl-SFA derivatives were well separated without any interfering peaks in plasma samples. The characteristic ions at M-15, constituting the base peaks in the electron impact mass spectra for 11 SFAs, permitted their sensitive detection by GC-MS in the selected ion monitoring (SIM) mode. The SIM responses were linear with correlation coefficients varying from 0.993 to 0.999 in the concentration range of 0.05 to approximately 50 microg/ml for the 11 SFAs. The detection limits for SIM of the SFAs varied in the range of 0.05 to approximately 10.0 pg. When applied to the plasma samples of normal subjects and patients with X-linked adenoleukodystrophy, which is one of the hereditary peroxisomal disorders, the present method enabled us to determine the SFAs with good sensitivity and good overall precision and accuracy within the concentration ranges of 0.14 to approximately 82.35 micromol/l.

  2. Electron Radiolysis of Ammonium Perchlorate: A Reflectron Time-of-Flight Mass Spectrometric Study.

    PubMed

    Góbi, Sándor; Bergantini, Alexandre; Turner, Andrew M; Kaiser, Ralf I

    2017-05-25

    Thin films of ammonium perchlorate (NH4ClO4) were exposed to energetic electrons at 5.5 K to explore the radiolytic decomposition mechanisms. The effects of radiolysis were monitored on line and in situ via Fourier transform infrared spectroscopy (FTIR) in the condensed phase along with electron impact ionization quadrupole mass spectrometry (EI-QMS) and single-photon photoionization reflectron time-of-flight mass spectrometry (PI-ReTOF-MS) during the temperature-programmed desorption (TPD) phase to probe the subliming molecules. Three classes of molecules were observed: (i) nitrogen bearing species [ammonia (NH3), hydroxylamine (NH2OH), molecular nitrogen (N2), nitrogen dioxide (NO2)], (ii) chlorine carrying molecules [chlorine monoxide (ClO), chlorine dioxide (ClO2), dichlorine trioxide (Cl2O3)], and (iii) molecular oxygen (O2). Decay profiles of the reactants along with the growth profiles of the products as derived from the infrared data were fit kinetically to obtain a reaction mechanism with the initial steps involving a proton loss from the ammonium ion (NH4(+)) yielding ammonia (NH3) and the decomposition of perchlorate ion (ClO4(-)) forming chlorate ion (ClO3(-)) plus atomic oxygen. The latter oxidized ammonia to hydroxylamine and ultimately to nitrogen dioxide. Molecular oxygen and nitrogen were found to be formed via recombination of atomic oxygen and multistep radiolysis of ammonia, respectively.

  3. Electrospray ionization mass spectrometric detection of low polar compounds by adding NaAuCl4.

    PubMed

    Moriwaki, Hiroshi

    2016-11-01

    Liquid chromatography electrospray ionization mass spectrometry (LC/ESI/MS) has been widely used for various analyses. However, it is difficult to use LC/ESI/MS for the analysis of low polar compounds, such as polycyclic aromatic hydrocarbons. It is well known that AuCl4(-) ion decomposes to AuCl3 by heating, and AuCl3 is a strong π-electrophilic Lewis acid. Low polar compounds (pyrene, benzo[a]pyrene, perylene, benzo[ghi]perylene, dibenzothiophene and p-dimethoxybenzene) were detected by ESI/MS in the positive ion mode by adding NaAuCl4 . The low polar compound interacts with AuCl3 formed at the ESI interface, and undergoes electron transfer to AuCl3 . The radical cation of the low polar compound was then detected by MS. In addition, the LC/ESI/MS determination of polycyclic aromatic hydrocarbons by the post-column addition of NaAuCl4 was studied. © 2016 The Authors Journal of Mass Spectrometry Published by John Wiley & Sons Ltd.

  4. Engineering cell-compatible paper chips for cell culturing, drug screening, and mass spectrometric sensing.

    PubMed

    Chen, Qiushui; He, Ziyi; Liu, Wu; Lin, Xuexia; Wu, Jing; Li, Haifang; Lin, Jin-Ming

    2015-10-28

    Paper-supported cell culture is an unprecedented development for advanced bioassays. This study reports a strategy for in vitro engineering of cell-compatible paper chips that allow for adherent cell culture, quantitative assessment of drug efficiency, and label-free sensing of intracellular molecules via paper spray mass spectrometry. The polycarbonate paper is employed as an excellent alternative bioscaffold for cell distribution, adhesion, and growth, as well as allowing for fluorescence imaging without light scattering. The cell-cultured paper chips are thus amenable to fabricate 3D tissue construction and cocultures by flexible deformation, stacks and assembly by layers of cells. As a result, the successful development of cell-compatible paper chips subsequently offers a uniquely flexible approach for in situ sensing of live cell components by paper spray mass spectrometry, allowing profiling the cellular lipids and quantitative measurement of drug metabolism with minimum sample pretreatment. Consequently, the developed paper chips for adherent cell culture are inexpensive for one-time use, compatible with high throughputs, and amenable to label-free and rapid analysis.

  5. Mass Spectrometric Characterization of Human N-acylethanolamine-hydrolyzing Acid Amidase

    PubMed Central

    West, Jay M.; Zvonok, Nikolai; Whitten, Kyle M.; Wood, JodiAnne T.; Makriyannis, Alexandros

    2013-01-01

    N-acylethanolamine-hydrolyzing acid amidase (NAAA) is a lysosomal enzyme that primarily degrades palmitoylethanolamine (PEA), a lipid amide that inhibits inflammatory responses. We developed a HEK293 cell line stably expressing the NAAA pro-enzyme (zymogen) and a single step chromatographic purification of the protein from the media. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry MALDI-TOF MS analysis of the zymogen (47.7 kDa) treated with Peptide-N-Glycosidase F (PNGase F) identified 4 glycosylation sites, and acid cleavage of the zymogen into α- and β-subunits (14.6 and 33.3 kDa) activated the enzyme. Size exclusion chromatography estimated the mass of the active enzyme as 45 ± 3 kDa, suggesting formation of an α/β heterodimer. MALDI-TOF MS fingerprinting covered more than 80% of the amino acid sequence, including the N-terminal peptides, and evidence for the lack of a disulfide bond between subunits. The significance of the cysteine residues was established by their selective alkylation resulting in almost complete loss of activity. The purified enzyme was kinetically characterized with PEA and a novel fluorogenic substrate, N-(4-methyl coumarin) palmitamide (PAMCA). The production of sufficient quantities of NAAA and a high throughput assay could be useful in discovering novel inhibitors and determining the structure and function of this enzyme. PMID:22040171

  6. Improving the quality of mass produced maps

    USGS Publications Warehouse

    Simley, J.

    2001-01-01

    Quality is critical in cartography because key decisions are often made based on the information the map communicates. The mass production of digital cartographic information to support geographic information science has now added a new dimension to the problem of cartographic quality, as problems once limited to small volumes can now proliferate in mass production programs. These problems can also affect the economics of map production by diverting a sizeable portion of production cost to pay for rework on maps with poor quality. Such problems are common to general industry-in response, the quality engineering profession has developed a number of successful methods to overcome these problems. Two important methods are the reduction of error through statistical analysis and addressing the quality environment in which people work. Once initial and obvious quality problems have been solved, outside influences periodically appear that cause adverse variations in quality and consequently increase production costs. Such errors can be difficult to detect before the customer is affected. However, a number of statistical techniques can be employed to detect variation so that the problem is eliminated before significant damage is caused. Additionally, the environment in which the workforce operates must be conductive to quality. Managers have a powerful responsibility to create this environment. Two sets of guidelines, known as Deming's Fourteen Points and ISO-9000, provide models for this environment.

  7. Fragment formula calculator (FFC): determination of chemical formulas for fragment ions in mass spectrometric data.

    PubMed

    Wegner, André; Weindl, Daniel; Jäger, Christian; Sapcariu, Sean C; Dong, Xiangyi; Stephanopoulos, Gregory; Hiller, Karsten

    2014-02-18

    The accurate determination of mass isotopomer distributions (MID) is of great significance for stable isotope-labeling experiments. Most commonly, MIDs are derived from gas chromatography/electron ionization mass spectrometry (GC/EI-MS) measurements. The analysis of fragment ions formed during EI, which contain only specific parts of the original molecule can provide valuable information on the positional distribution of the label. The chemical formula of a fragment ion is usually applied to derive the correction matrix for accurate MID calculation. Hence, the correct assignment of chemical formulas to fragment ions is of crucial importance for correct MIDs. Moreover, the positional distribution of stable isotopes within a fragment ion is of high interest for stable isotope-assisted metabolomics techniques. For example, (13)C-metabolic flux analyses ((13)C-MFA) are dependent on the exact knowledge of the number and position of retained carbon atoms of the unfragmented molecule. Fragment ions containing different carbon atoms are of special interest, since they can carry different flux information. However, the process of mass spectral fragmentation is complex, and identifying the substructures and chemical formulas for these fragment ions is nontrivial. For that reason, we developed an algorithm, based on a systematic bond cleavage, to determine chemical formulas and retained atoms for EI derived fragment ions. Here, we present the fragment formula calculator (FFC) algorithm that can calculate chemical formulas for fragment ions where the chemical bonding (e.g., Lewis structures) of the intact molecule is known. The proposed algorithm is able to cope with general molecular rearrangement reactions occurring during EI in GC/MS measurements. The FFC algorithm is able to integrate stable isotope labeling experiments into the analysis and can automatically exclude candidate formulas that do not fit the observed labeling patterns.1 We applied the FFC algorithm to create

  8. A novel photoelectrochemical flow cell with online mass spectrometric detection: oxidation of formic acid on a nanocrystalline TiO2 electrode.

    PubMed

    Reichert, Robert; Jusys, Zenonas; Behm, R Jürgen

    2014-12-07

    A novel thin-layer photoelectrochemical flow cell allowing the online mass spectrometric detection of volatile reaction products during photoelectrocatalytic reactions has been developed and applied for separating the contributions from photoelectrochemical water splitting and photoelectrooxidation of formic acid to the overall photocurrent in formic acid containing aqueous solution, using a nanocrystalline TiO2 (P25) thin-film electrode. The data reveal a clear suppression of the water oxidation reaction to O2 in the presence of formic acid. Advantages of this flow cell design over conventional photoelectrochemical cells with stagnant electrolyte in terms of mass transport will be demonstrated and discussed.

  9. Broad spectrum infrared thermal desorption of wipe-based explosive and narcotic samples for trace mass spectrometric detection.

    PubMed

    Forbes, Thomas P; Staymates, Matthew; Sisco, Edward

    2017-08-07

    Wipe collected analytes were thermally desorbed using broad spectrum near infrared heating for mass spectrometric detection. Employing a twin tube filament-based infrared emitter, rapid and efficiently powered thermal desorption and detection of nanogram levels of explosives and narcotics was demonstrated. The infrared thermal desorption (IRTD) platform developed here used multi-mode heating (direct radiation and secondary conduction from substrate and subsequent convection from air) and a temperature ramp to efficiently desorb analytes with vapor pressures across eight orders of magnitude. The wipe substrate experienced heating rates up to (85 ± 2) °C s(-1) with a time constant of (3.9 ± 0.2) s for 100% power emission. The detection of trace analytes was also demonstrated from complex mixtures, including plastic-bonded explosives and exogenous narcotics, explosives, and metabolites from collected artificial latent fingerprints. Manipulation of the emission power and duration directly controlled the heating rate and maximum temperature, enabling differential thermal desorption and a level of upstream separation for enhanced specificity. Transitioning from 100% power and 5 s emission duration to 25% power and 30 s emission enabled an order of magnitude increase in the temporal separation (single seconds to tens of seconds) of the desorption of volatile and semi-volatile species within a collected fingerprint. This mode of operation reduced local gas-phase concentrations, reducing matrix effects experienced with high concentration mixtures. IRTD provides a unique platform for the desorption of trace analytes from wipe collections, an area of importance to the security sector, transportation agencies, and customs and border protection.

  10. Development and validation of a liquid chromatography-tandem mass spectrometric assay for quantitative analyses of triptans in hair.

    PubMed

    Vandelli, Daniele; Palazzoli, Federica; Verri, Patrizia; Rustichelli, Cecilia; Marchesi, Filippo; Ferrari, Anna; Baraldi, Carlo; Giuliani, Enrico; Licata, Manuela; Silingardi, Enrico

    2016-04-01

    Triptans are specific drugs widely used for acute treatment of migraine, being selective 5HT1B/1D receptor agonists. A proper assumption of triptans is very important for an effective treatment; nevertheless patients often underuse, misuse, overuse or use triptans inconsistently, i.e., not following the prescribed therapy. Drug analysis in hair can represent a powerful tool for monitoring the compliance of the patient to the therapy, since it can greatly increase the time-window of detection compared to analyses in biological fluids, such as plasma or urine. In the present study, a liquid chromatography-tandem mass spectrometric (LC-MS/MS) method has been developed and validated for the quantitative analysis in human hair of five triptans commonly prescribed in Italy: almotriptan (AL), eletriptan (EP), rizatriptan (RIZ), sumatriptan (SUM) and zolmitriptan (ZP). Hair samples were decontaminated and incubated overnight in diluted hydrochloric acid; the extracts were purified by mixed-mode SPE cartridges and analyzed by LC-MS/MS under gradient elution in positive multiple reaction monitoring (MRM) mode. The procedure was fully validated in terms of selectivity, linearity, limit of detection (LOD) and lower limit of quantitation (LLOQ), accuracy, precision, carry-over, recovery, matrix effect and dilution integrity. The method was linear in the range 10-1000pg/mg hair, with R(2) values of at least 0.990; the validated LLOQ values were in the range 5-7pg/mg hair. The method offered satisfactory precision (RSD <10%), accuracy (90-110%) and recovery (>85%) values. The validated procedure was applied on 147 authentic hair samples from subjects being treated in the Headache Centre of Modena University Hospital in order to verify the possibility of monitoring the corresponding hair levels for the taken triptans.

  11. A carboxy-terminal affinity tag for the purification and mass spectrometric characterization of integral membrane proteins.

    PubMed

    Wong, Julie P; Reboul, Emmanuelle; Molday, Robert S; Kast, Juergen

    2009-05-01

    G-protein-coupled receptors (GPCRs) and other structurally and functionally related membrane proteins represent particularly attractive targets for drug discovery. Integral membrane proteins are often difficult to purify from native contexts, and lack of sufficient quantities hampers subsequent structural and functional proteomic studies. We describe here an optimized enrichment strategy involving a membrane protein-compatible 1D4 affinity tag that is derived from the carboxy-terminal nine amino residues of bovine rhodopsin, and its corresponding tag-specific, high-affinity monoclonal antibody. When two GPCRs as well as two related ATP binding cassette (ABC) transporters are expressed in their functional forms in human cell lines, we have shown that a single detergent and wash condition can be employed for the purification of all said membrane proteins. Subsequent in-gel digestion with trypsin and mass spectrometric peptide analysis resulted in high sequence coverage for the ABC transporters ABCA1-1D4 and ABCA4-1D4. In contrast, digestion by various enzymatic combinations was necessary to obtain the best sequence coverage for affinity-enriched GPCRs CXCR4-1D4 and CCR5-1D4 as compared against other entries in an annotated spectrum library. Furthermore, specific enzyme combinations were necessary to produce suitable peptides for deducing N-glycosylation sites on CXCR4. Our results demonstrate that the 1D4-tag enrichment strategy is a versatile tool for the characterization of integral membrane proteins that can be employed for functional proteomic studies.

  12. High-resolution mass spectrometric identification and quantification of glucocorticoid compounds in various wastewaters in the Netherlands.

    PubMed

    Schriks, Merijn; van Leerdam, Jan A; van der Linden, Sander C; van der Burg, Bart; van Wezel, Annemarie P; de Voogt, Pim

    2010-06-15

    In the past two decades much research effort has focused on the occurrence, effects, and risks of estrogenic compounds. However, increasing emissions of new emerging compounds may also affect the action of hormonal pathways other than the estrogenic hormonal axis. Recently, a suite of novel CALUX bioassays has become available that enables looking further than estrogenic effects only. By employing these bioassays, we recently showed high glucocorticogenic activity in wastewaters collected at various sites in The Netherlands. However, since bioassays provide an integrated biological response, the identity of the responsible biological compounds remained unknown. Therefore, our current objective was to elucidate the chemical composition of the wastewater extracts used in our previous study by means of LC-high-resolution Orbitrap MS/MS and to determine if the compounds quantified could account for the observed glucocorticoid responsive (GR) CALUX bioassay response. The mass spectrometric analysis revealed the presence of various glucocorticoids in the range of 13-1900 ng/L. In extracts of hospital wastewater-collected prior to sewage treatment-several glucocorticoids were identified (cortisol 275-301 ng/L, cortisone 381-472 ng/L, prednisone 117-545 ng/L, prednisolone 315-1918 ng/L, and triamcinolone acetonide 14-41 ng/L) which are used to treat a great number of human pathologies. A potency balance calculation based on the instrumental analyses and relative potencies (REPs) of the individual glucocorticoids supports the conclusion that triamcinolone acetonide (REP = 1.3), dexamethasone (REP = 1), and prednisolone (REP = 0.2) are the main contributors to the glucocorticogenic activity in the investigated wastewater extracts. The action of these compounds is concentration additive and the overall glucocorticogenic activity can be explained to a fairly large extent by their contribution.

  13. Liquid chromatography-electrospray ionization tandem mass spectrometric analysis of 2-alkylcyclobutanones in irradiated chicken by precolumn derivatization with hydroxylamine.

    PubMed

    Ye, Yuran; Liu, Hanxia; Horvatovich, Peter; Chan, Wan

    2013-06-19

    Food irradiation is a common preservation method that is used in many countries. The ability to identify irradiated food is important for assuring compliance with regulatory policies, such as food labeling requirements, and for informed consumer choice. There is thus a significant demand for analytical methods of high sensitivity and selectivity to identify irradiated food, especially for foods subjected to low-dose irradiation and for processed or composite foods that contain small quantities of irradiated ingredients. 2-Alkylcyclobutanones (2-ACBs) are uniquely formed during food irradiation and have been adopted by the European Committee for Standardization as signature biomarkers for the identification of irradiated foods. We now report the development of a novel assay for quantification of 2-ACBs in γ-irradiated food by liquid extraction of fat content followed by precolumn derivatization and liquid chromatography-tandem mass spectrometric (LC-MS/MS) detection. Precolumn derivatization with hydroxylamine introduced a polar functional group into the otherwise nonpolar 2-ACBs, which greatly enhanced ESI-MS response. The method was validated for extraction efficiency, precision, accuracy, and detection limit. In comparison with the current GC-MS based European official method (EN1785:2003) for 2-ACBs determination, our new LC-MS/MS method offers a more efficient sample processing protocol with reduced solvent consumption. More importantly, the combination of chemical derivatization and LC-MS/MS detection significantly enhanced the analytical sensitivity of the method, which allows confident identification of food irradiated with as little as 10 Gy. To the best of our knowledge, this is the first report of 2-ACB determination by LC-MS/MS and the first analytical method allowing confident identification of irradiated food at dosage of down to 10 Gy.

  14. Tandem capillary column gas chromatography-mass spectrometric determination of the organophosphonate nerve agent surrogate dimethyl methylphosphonate in gaseous phase.

    PubMed

    McDaniel, Les N; Romero, Nicholas A; Boyd, Jonathan; Coimbatore, Gopal; Cobb, George P

    2010-06-15

    A procedure based on capillary column gas chromatographic-mass spectrometric (GC-MS) confirmation was developed for the verification of the ubiquitous and versatile chemical and nerve agent simulant, dimethyl methyl phosphonate (DMMP; CAS# 756-79-6), from gaseous samples. This method was developed to verify low nanogram DMMP concentrations during testing of a nerve agent detection system. Standard solutions of 1, 5, 10, 50, 100, 500, and 1000ng/ml DMMP in acetonitrile were employed. Through 15 calibration curves using the 5 lowest concentrations, coefficient of determination (r(2)) values showed a mean of 0.998 (0.992-1.000). An additional 15 calibration curves likewise containing 5 concentrations of DMMP spanning 3 orders of magnitude (1, 50, 100, 500, and 1000ng/ml) yielded a mean r(2) of 0.997 (0.991-1.000). Sixty-five nitrogen diluted gaseous samples varying from 1.0 to 10.0microl in volume were analyzed and concentrations of DMMP ranging from 1 to 1000ng/ml were confirmed. An additional 35 vapor samples in UHP N(2) ranging in DMMP concentration from 5.8microg/m(3) to 1.0mg/m(3) were analyzed by increasing sample volume range to between 10.0 and 100microl. For gaseous samples with volumes>1.0microl, the lowest concentration observed was 5.8microg/m(3). The method detection limit (Appendix B of Title 40 CFR, United States) for 1.0microl autoinjected standards in acetonitrile was determined to be 0.331ng/ml. Method precision for 15 independently analyzed standards of 25ng/ml had a relative standard deviation of 1.168. This method demonstrated high linearity across a wide range of concentrations, as well as excellent sensitivity and repeatability, and proved applicable to other lower alkyl-phosphonates.

  15. Gas chromatographic/mass spectrometric analysis of morphine and codeine in human urine of poppy seed eaters.

    PubMed

    elSohly, H N; Stanford, D F; Jones, A B; elSohly, M A; Snyder, H; Pedersen, C

    1988-03-01

    In this study, poppy seeds were examined for a natural constituent that might serve as a maker for the seeds' ingestion as opposed to opiate abuse. Thebaine was selected as possible marker, since it was found to be a component of all poppy seeds examined and was not a natural component of different heroin samples. During the course of this investigation, a new extraction and cleanup procedure was developed for the gas chromatographic/nitrogen phosphorus detection (GC/NPD) and gas chromatographic/mass spectrometric (GC/MS) analysis of morphine and codeine in urine. A linear response, over a concentration range of 25 to 600 ng/mL, was obtained for codeine and morphine (r = 0.9982 and 0.9947, respectively). The minimum detectable level (LOD) and limit of quantitation (LOQ) for morphine were 10 and 30 ng/mL, respectively; whereas LOD and LOQ for codeine were 2 and 8 ng/mL, respectively. The coefficients of variance (CV, n = 6) for morphine and codeine analyses at the 100-ng/mL level were 13.3 and 4.6%, respectively. This procedure was used for the analysis of urine samples from five poppy seed eaters who each ingested 200 g of poppy seed cake. Results indicated that significant amounts of morphine and codeine are excreted in urine and that in all subjects, at least at one point in time, the apparent morphine concentration as determined by radioimmunoassay (RIA) analysis exceeded the cutoff value (300 ng/mL) established for screening. Thebaine was not detected in urine specimens collected following poppy seeds ingestion and thus could not be used as a marker.

  16. Comparative Analysis of Volatile Defensive Secretions of Three Species of Pyrrhocoridae (Insecta: Heteroptera) by Gas Chromatography-Mass Spectrometric Method

    PubMed Central

    Krajicek, Jan; Havlikova, Martina; Bursova, Miroslava; Ston, Martin; Cabala, Radomir; Exnerova, Alice; Stys, Pavel; Bosakova, Zuzana

    2016-01-01

    The true bugs (Hemiptera: Heteroptera) have evolved a system of well-developed scent glands that produce diverse and frequently strongly odorous compounds that act mainly as chemical protection against predators. A new method of non-lethal sampling with subsequent separation using gas chromatography with mass spectrometric detection was proposed for analysis of these volatile defensive secretions. Separation was performed on Rtx-200 column containing fluorinated polysiloxane stationary phase. Various mechanical irritation methods (ultrasonics, shaking, pressing bugs with plunger of syringe) were tested for secretion sampling with a special focus on non-lethal irritation. The preconcentration step was performed by sorption on solid phase microextraction (SPME) fibers with different polarity. For optimization of sampling procedure, Pyrrhocoris apterus was selected. The entire multi-parameter optimization procedure of secretion sampling was performed using response surface methodology. The irritation of bugs by pressing them with a plunger of syringe was shown to be the most suitable. The developed method was applied to analysis of secretions produced by adult males and females of Pyrrhocoris apterus, Pyrrhocoris tibialis and Scantius aegyptius (all Heteroptera: Pyrrhocoridae). The chemical composition of secretion, particularly that of alcohols, aldehydes and esters, is species-specific in all three pyrrhocorid species studied. The sexual dimorphism in occurrence of particular compounds is largely limited to alcohols and suggests their epigamic intraspecific function. The phenetic overall similarities in composition of secretion do not reflect either relationship of species or similarities in antipredatory color pattern. The similarities of secretions may be linked with antipredatory strategies. The proposed method requires only a few individuals which remain alive after the procedure. Thus secretions of a number of species including even the rare ones can be

  17. A novel high-throughput automated chip-based nanoelectrospray tandem mass spectrometric method for PAMPA sample analysis.

    PubMed

    Balimane, Praveen V; Pace, Ellen; Chong, Saeho; Zhu, Mingshe; Jemal, Mohammed; Pelt, Colleen K Van

    2005-09-01

    Parallel artificial membrane permeability assay (PAMPA) has recently gained popularity as a novel, high-throughput assay capable of rapidly screening compounds for their permeability characteristics in early drug discovery. The analytical techniques typically used for PAMPA sample analysis are HPLC-UV, LC/MS or more recently UV-plate reader. The LC techniques, though sturdy and accurate, are often labor and time intensive and are not ideal for high-throughput. On the other hand, UV-plate reader technique is amenable to high-throughput but is not sensitive enough to detect the lower concentrations that are often encountered in early drug discovery work. This article investigates a novel analytical method, a chip-based automated nanoelectrospray mass spectrometric method for its ability to rapidly analyze PAMPA permeability samples. The utility and advantages of this novel analytical method is demonstrated by comparing PAMPA permeability values obtained from nanoelectrospray to those from conventional analytical methods. Ten marketed drugs having a broad range of structural space, physico-chemical properties and extent of intestinal absorption were selected as test compounds for this investigation. PAMPA permeability and recovery experiments were conducted with model compounds followed by analysis by UV-plate reader, UV-HPLC as well as the automated nanoelectrospray technique (nanoESI-MS/MS). There was a very good correlation (r(2) > 0.9) between the results obtained using nanoelectrospray and the other analytical techniques tested. Moreover, the nanoelectrospray approach presented several advantages over the standard techniques such as higher sensitivity and ability to detect individual compounds in cassette studies, making it an attractive high-throughput analytical technique. Thus, it has been demonstrated that nanoelectrospray analysis provides a highly efficient and accurate analytical methodology to analyze PAMPA samples generated in early drug discovery.

  18. Buffer system for the separation of neutral and charged small molecules using micellar electrokinetic chromatography with mass spectrometric detection.

    PubMed

    Goetzinger, Wolfgang K; Cai, Hong

    2005-06-24

    An organic buffer system will be discussed that is suitable for the separation of neutral as well as charged molecules be means of micellar electrokinetic chromatography (MEKC). The buffers are based on the combination of a long chain alkyl acid, such as lauric acid with ammonium hydroxide or an organic base such as tris-hydroxymethylaminomethane (Tris). The resulting buffer system is able to separate neutral compounds based on its micellar properties. These buffers exhibit much reduced conductivity compared to traditional MEKC buffers, such as sodium dodecylsulfate (SDS), which contain inorganic salts. They also have inherent buffer capacity at high pH resulting from the basic buffer component, which in our studies had pK values from about 8-11. The separations that were observed showed high efficiency with plate counts in many cases above 500,000 plates per meter. The reduced conductivity allowed for the application of much higher electric fields, resulting in very fast analysis times. Alternatively, an increase in detection sensitivity could be achieved, as the reduced conductivity allowed for the use of capillaries with lager internal diameters. Combinations of different alkyl acids and organic bases provided for significant flexibility in selectivity tuning. Finally, the fact that the organic micellar buffer systems discussed here do not contain inorganic ions, allows for coupling with mass spectrometric (MS) detection. The possibility of MS detection combined with the high speed in analysis that can be obtained using these organic buffer systems, could make this approach an interesting option for high throughput analysis of combinatorial libraries.

  19. Real-time mass spectrometric study of the methanol crossover in a direct methanol fuel cell

    SciTech Connect

    Wang, J.T.; Wasmus, S.; Savinell, R.F.

    1996-04-01

    The products of methanol crossover through the acid-doped polybenzimidazole polymer electrolyte membrane (PBI PEM) to the cathode of a prototype direct methanol fuel cell (DMFC) were analyzed using multipurpose electrochemical mass spectrometry (MPEMS) coupled to the cathode exhaust gas outlet. It was found that the methanol crossing over reacts almost quantitatively to CO{sub 2} at the cathode with the platinum of the cathode acting as a heterogeneous catalyst. The cathode open-circuit potential is inversely proportional to the amount of CO{sub 2} formed. A poisoning effect on the oxygen reduction also was found. Methods for the estimation of the methanol crossover rate at operating fuel cells are suggested.

  20. Rapid on-membrane proteolytic cleavage for Edman sequencing and mass spectrometric identification of proteins.

    PubMed

    Pham, Victoria C; Henzel, William J; Lill, Jennie R

    2005-11-01

    A method for the rapid limited enzymatic cleavage of PVDF membrane-immobilized proteins is described. This method allows the fast characterization of PVDF blotted proteins by peptide mass fingerprinting (Henzel, W. J., Billeci, T. M., Stults, J. T., Wong, S. C., Grimley, C., Wantanabe, C., Proc. Natl. Acad. Sci. USA 1993, 90, 5011-5015), LC-MS/MS, or N-terminal sequencing and has been demonstrated on a range of proteins using a full complement of proteolytic enzymes. This technique allows the generation of proteolytic fragments between 5 and 60 min (depending on the enzyme employed), which is significantly faster than previously reported on-membrane digestion methods. To date, this on-membrane rapid digestion protocol has aided in the identification and confirmation of mutation sites in over 200 recombinant proteins.

  1. [MALDI-TOF mass spectrometric identification of novel intercellular space peptides].

    PubMed

    Il'ina, A P; Kulikova, O G; Mal'tsev, D I; Krasnov, M S; Rybakova, E Iu; Skripnikova, V S; Kuznetsova, E S; Buriak, A K; Iamskova, V P; Iamskov, I A

    2011-01-01

    We performed the matrix-assisted laser desorption/ionisation, time-of-flight mass spectrometry (MALDI-TOF) analysis of the peptides entering into the composition of not yet explored bioregulators derived from the extracellular matrix of the tissues of the various organs of the mammals, and also plants and fungi. The study included 15 different mammalian tissues, 13 species of plants, and 2 species of fungi. Exploring the bioregulators derived from eye tissues, we demonstrated that their composition includes peptide components with the same values of the molecular weight. The composition of the bioregulators derived from the tissues of various organs of mammals or different species of plants and fungi includes the peptides with different values of molecular weight. Obtained data indicate the growing evidence of the assumptions about the major function of the bioregulators of this group--their involvement in the regulation of tissue-organ homeostasis in the biological systems.

  2. Advances in sample preparation in electromigration, chromatographic and mass spectrometric separation methods.

    PubMed

    Gilar, M; Bouvier, E S; Compton, B J

    2001-02-16

    The quality of sample preparation is a key factor in determining the success of analysis. While analysis of pharmaceutically important compounds in biological matrixes has driven forward the development of sample clean-up procedures in last 20 years, today's chemists face an additional challenge: sample preparation and analysis of complex biochemical samples for characterization of genotypic or phenotypic information contained in DNA and proteins. This review focuses on various sample pretreatment methods designed to meet the requirements for the analysis of biopolymers and small drugs in complex matrices. We discuss the advances in development of solid-phase extraction (SPE) sorbents, on-line SPE, membrane-based sample preparation, and sample clean-up of biopolymers prior to their analysis by mass spectrometry.

  3. [Mass Spectrometric Methods for Colorative Mechanism Analysis of Yaozhou Porcelain Glaze].

    PubMed

    Xiao, Yuan-fang; He, Miao-hong; Zhang, Shu-di; Hang, Wei

    2015-09-01

    An in-house-built femtosecond laser ionization time-of-flight mass spectrometry (fs-LI-TOFMS) has been applied to the multi-elemental analysis of porcelain glaze from Yaozhou kiln. The samples are selected representing products of different dynasties, including Tang, Five, Song, Jin, and Ming Dynasty. For exploring the colorative mechanism of Yaozhou porcelain through the elemental analysis of the glaze, the effects of all potential coloring elements, especially transition elements, were considered. There was a speculation that the typical Co-Cr-Fe-Mn recipe was used in the fabrication of Yaozhou black glaze; the low content of Fe and high content of Ni resulted in the porcelain of white glaze; an increase content of P could lead the porcelain to be yellow-glazed. Undoubtedly, this research is an important supplement to the study of the colorative mechanism of the Yaozhou porcelain system.

  4. Interaction of water vapor with silicate glass surfaces: Mass-spectrometric investigations

    NASA Astrophysics Data System (ADS)

    Kudriavtsev, Yu.; Asomoza-Palacio, R.; Manzanilla-Naim, L.

    2017-05-01

    The secondary ion mass-spectroscopy technique was used to study the results of hydration of borosilicate, aluminosilicate, and soda-lime silicate glasses in 1H2 18O water vapor containing 97% of the isotope 18O. It is shown that hydration of the surface of the soda-lime silicate glass occurs as a result of the ion-exchange reaction with alkali metals. In the case of borosilicate and aluminosilicate glasses, water molecules decompose on the glass surface, with the observed formation of hydrogenated layer in the glass being the result of a solid-state chemical reaction—presumably, with the formation of hydroxides from aluminum and boron oxides.

  5. Nonenzymatic modification of Ubiquitin under high-pressure and -temperature treatment: mass spectrometric studies.

    PubMed

    Kijewska, Monika; Radziszewska, Karolina; Kielmas, Martyna; Stefanowicz, Piotr; Szewczuk, Zbigniew

    2015-01-21

    The effect of high-pressure and/or high-temperature on the glycation of a model protein (ubiquitin) was investigated by mass spectrometry. This paper reports the impact of high pressure (up to 1200 MPa) on the modification of a ubiquitin using ESI-MS measurements. The application of glucose labeled with stable isotope allows a quantitative assessment of modification under the conditions of high-pressure (HPG) and high-temperature (HTG) glycation. A higher degree of modification was observed for the sample heated at 80 °C for 25 min under atmospheric pressure than for sample treated under high pressure. In samples treated at pressure below 400 MPa an insignificant increase of glycation level was observed, whereas high pressure (>600 MPa) has only a minor effect on the number of hexose moieties (Fru) attached to the lysine residue side chain.

  6. Mass spectrometric identification of cyclic polysulfides in sediment of the Eastern Gulf of Finland. I.

    PubMed

    Khoroshko, Larisa O; Takhistov, Viatcheslav V; Petrova, Varvara N; Viktorovskii, Igor V; Lahtiperä, Mirja; Paasivirta, Jaakko

    2004-01-01

    Structures of six cyclic polysulfides, previously unknown as organic environmental pollutants, were analyzed from a sediment sample from the Eastern Gulf of Finland. The determinations were done by gas chromatography connected to mass spectrometry. High resolution (HRMS) measurements of the isotopic composition of four compounds could be done to confirm their molecular formulae. Total low resolution (LRMS) spectra were used to elucidate structures of all six compounds by thermochemical approach, application of fragmentation rules and by ICLU simulation of the spectra. The compounds were deduced to be (in the order of GC- retention) 1,2,4-trithiacycloheptane, tetrathiacyclopentane, 1,2,4,5-tetrathia-cyclohexane, 1,2,3,4- tetrathiacycloheptane, 1,2,3,4-tetrathiacyclohexane and 1,2,4,6-tetrathiacyclooctane.

  7. Profiling of Piper betle Linn. cultivars by direct analysis in real time mass spectrometric technique.

    PubMed

    Bajpai, Vikas; Sharma, Deepty; Kumar, Brijesh; Madhusudanan, K P

    2010-12-01

    Piper betle Linn. is a traditional plant associated with the Asian and southeast Asian cultures. Its use is also recorded in folk medicines in these regions. Several of its medicinal properties have recently been proven. Phytochemical analysis showed the presence of mainly terpenes and phenols in betel leaves. These constituents vary in the different cultivars of Piper betle. In this paper we have attempted to profile eight locally available betel cultivars using the recently developed mass spectral ionization technique of direct analysis in real time (DART). Principal component analysis has also been employed to analyze the DART MS data of these betel cultivars. The results show that the cultivars of Piper betle could be differentiated using DART MS data.

  8. Letter: Mass spectrometric approach of high pH- and copper-induced glutathione oxidation.

    PubMed

    Drochioiu, Gabi; Ion, Laura; Ciobanu, Catalina; Habasescu, Laura; Mangalagiu, Ionel

    2013-01-01

    The interaction between copper ions and gamma-L-glutamyl-L-cysteinyl-glycine [glutathione (GSH)] molecules may lead to the formation of the physiologically occurring Cu[I)-[GSH]2 and Cu(II)-GSSG complexes. Since glutathione depletion in neurons and aberrant copper metabolism have been implicated in several neurodegenerative disorders, we studied here the interaction of GSH with copper ions (Cu2+) by electrospray ionization ion trap mass spectrometry (ESI-IT-MS). Besides, we extended this approach to pH in excess of 10 by adding ethanolamine to the solution being investigated. As a result, the ESI-IT-MS spectra revealed novel aspects regarding the speciation of copper-glutathione complex.

  9. Mass spectrometric study of rare earth oxide equilibria in the glow discharge

    SciTech Connect

    Mei, Y.; Harrison, W.W. )

    1993-12-01

    Glow discharge mass spectrometry has been used to study redox equilibria reactions of lanthanum and lanthanum oxide in an argon glow discharge. Introduction of the primary reagents of La and LaO is by sputter ejection from a cathodic sample. The plasma chemistry is greatly affected by oxidizing and reducing agents in the plasma, most prominent of which is residual water, shown here to reduce greatly the La/LaO ratio even at trace levels of water vapor. The injection of controlled amounts of water vapor was used to demonstrate this effect. Mixtures of Ar and Ne permitted the study of atomization changes for Ag, Ti, and La samples. [sup 18]O-enriched water was also used to follow oxidation processes in the plasma. Attempts were made to differentiate between oxygen reactants arising from sputtered oxide sample and those originating in the injected water. 32 refs., 8 figs.

  10. Computerised gas chromatographic-mass spectrometric analysis of complex mixtures of alkyl porphyrins.

    PubMed

    Marriott, P J; Gill, J P; Evershed, R P; Hein, C S; Eglinton, G

    1984-01-01

    Computerised capillary gas chromatography-mass spectrometry (GC-MS) analysis of complex mixtures of alkyl porphyrins, as their bis-(trimethylsiloxy)silicon(IV) and bis(tert.-butyldimethylsiloxy)silicon(IV) derivatives, is described. The latter derivative is more suitable for routine GC-MS analysis. This computerised GC-MS approach, when applied to the alkyl porphyrins of two geological samples, a bitumen (Gilsonite, Eocene age, UT, U.S.A.) and a crude oil (Boscan, Cretaceous age, West Venezuela), has revealed the highly complex compositions of these fractions. Computer-aided data processing, using relative retention index (RRI) calculations, facilitated the classification of the chromatographic peaks according to structural type and membership of pseudo-homologous series. Computerised GC-MS is compared with, and contrasted to high-performance liquid chromatography as a means of petroporphyrin analysis.

  11. Ion exchange separation of chromium from natural water matrix for stable isotope mass spectrometric analysis

    USGS Publications Warehouse

    Ball, J.W.; Bassett, R.L.

    2000-01-01

    A method has been developed for separating the Cr dissolved in natural water from matrix elements and determination of its stable isotope ratios using solid-source thermal-ionization mass spectrometry (TIMS). The separation method takes advantage of the existence of the oxidized form of Cr as an oxyanion to separate it from interfering cations using anion-exchange chromatography, and of the reduced form of Cr as a positively charged ion to separate it from interfering anions such as sulfate. Subsequent processing of the separated sample eliminates residual organic material for application to a solid source filament. Ratios for 53Cr/52Cr for National Institute of Standards and Technology Standard Reference Material 979 can be measured using the silica gel-boric acid technique with a filament-to-filament standard deviation in the mean 53Cr/52Cr ratio for 50 replicates of 0.00005 or less. (C) 2000 Elsevier Science B.V. All rights reserved.

  12. Gas chromatography - mass spectrometric analysis of four polluted river waters for phenolic and organic compounds.

    PubMed

    Nomani, A A; Ajmal, M; Ahmad, S

    1996-03-01

    Forty-four water samples from eleven sampling points were collected from four highly polluted rivers of northern India once in each four seasons during 1988-1989. The samples were analyzed for phenol, chlorophenols, a few bromophenols and other organics. Phenol was found to be absent in all the analyzed samples. Trichlorophenol and pentachlorophenol were frequently detected. Comparatively, the Ganges river was most polluted at Kannauj followed by Narora, Kachala and Fatehgarh. Maximum phenols were found at Mathura downstream of the Yamuna river followed by Mathura upstream, Okhla, ITO and none at Wazirabad. No phenols were detected in the water of the rivers Hindon and Kali at Ghaziabad and Aligarh, respectively. Some other organic pollutants were also identified by their mass spectra and supported by data from the computerized library, but, not quantified.

  13. Gas chromatographic-mass spectrometric determination of adipate-based polymeric plasticizers in foods.

    PubMed

    Castle, L; Mercer, A J; Gilbert, J

    1988-01-01

    A method for the quantitative determination of adipate-based polymeric plasticizers in foods is described. The procedure involves extraction from the food and transmethylation of the polymeric plasticizer to form dimethyladipate (DMA). The derivative is cleaned up by size-exclusion chromatography and determined by capillary gas chromatography-mass spectrometry with selected ion monitoring. The use of a deuterated internal standard at the extraction stage enables quantitation by stable isotope dilution. A detection limit of 0.1 mg/kg of the polymeric plasticizer in foods and a relative standard deviation of 4% have been achieved routinely. The method has been applied successfully to the analysis of cheese, sandwiches, meat, biscuits, and cake that have been in contact with polymeric plasticized poly(vinyl chloride) films.

  14. Novel mass spectrometric instrument for gaseous and particulate characterization and monitoring

    NASA Astrophysics Data System (ADS)

    Coggiola, M. J.; Becker, C. H.; Witham, C. L.

    1994-10-01

    An instrument is being developed that will be capable of providing real-time (less than 1 minute), quantitative, chemical analysis of gaseous and particulate pollutants generated from DOE waste cleanup activities. The instrument can detect and identify volatile organic compounds, polynuclear aromatic hydrocarbons, heavy metals, and transuranic species released during waste cleanup. It consists of an isokinetic sampler operable up to 500 K and wide flow rate range, a high- to low-pressure transition and sampling region separating particles from vapors for separate analysis, two small mass spectrometers (one for organic analysis by field ionization and one for particulate analysis by thermal pyrolysis and electron-impact ionization), and a powerful PC for control/data acquisition. Initially, the instrument will used with the K-1435 Toxic Substances Control Act (TSCA) incinerator at K-25; other applications are also possible, e.g., vitrification monitoring, storage tank offgassing analysis, etc. It will be easily transportable.

  15. Novel mass spectrometric instrument for gaseous and particulate characterization and monitoring

    NASA Astrophysics Data System (ADS)

    Coggiola, M. J.

    1994-07-01

    Purpose of the instrument is for real-time (less than 1 min), ppB analysis of gaseous/particulate pollutants (VOC's, PAH's, heavy metals, transuranics) from DOE waste cleanup. It will consist of an isokinetic sampler, a pressure transition and sampling region for parallel analyses, two small mass spectrometers (one for organic analysis using field ionization, one 'ion trap' for particulates using pyrolysis and electron-impact ionization), and a personal computer. A dimethylsilicone membrane will be used for the organic vapors. A forward-backward coincidence method will be used in the laser scattering particle detector. The instrument will be easily transportable to DOE waste sites, such as waste storage tanks.

  16. High-resolution mass spectrometric study of pure helium droplets, and droplets doped with krypton

    NASA Astrophysics Data System (ADS)

    Schöbel, H.; Bartl, P.; Leidlmair, C.; Denifl, S.; Echt, O.; Märk, T. D.; Scheier, P.

    2011-07-01

    Mass spectra of doped and undoped helium droplets are presented. The high resolution of the time-of-flight spectrometer ( m/ Δm ≅ 5000) makes it possible to fully resolve small helium cluster ions from impurities and to unambiguously identify abundance anomalies in the size distribution of He n +. The yield of He4 + shows the well-known enhancement relative to other small cluster ions when the expansion changes from sub- to supercritical, provided the electron energy exceeds a value of 40 ± 1 eV, the threshold for formation of electronically excited ions. Upon doping with krypton, pure Kr n + cluster ions containing up to 41 Kr atoms are observed. The spectra exhibit abundance anomalies at 13, 16, 19, 22 & 23, 26 and 29, in agreement with spectra obtained by ionization of bare krypton clusters that are formed in neat supersonic beams. Mixed clusters He m Kr+ indicate closure of a solvation shell at m = 12.

  17. Sensitive and specific liquid chromatographic-tandem mass spectrometric assay for barnidipine in human plasma.

    PubMed

    Pawula, M; Watson, D; Teramura, T; Watanabe, T; Higuchi, S; Cheng, K N

    1998-11-20

    A sensitive and specific LC-MS-MS assay has been developed and validated for barnidipine (1-benzyl-3-pyrrolidinyl)methyl-2,6-dimethyl-4(m-nitrophenyl)-1,4-dihydr opyridine-3,5-dicarboxylate). The assay involves a simple and rapid solid-phase extraction procedure. Sample analysis was on a Spherisorb S3ODS2 100 mmX2 mm I.D. column, with a Finnigan TSQ 7000 mass spectrometer, using an electrospray interface and selective reaction monitoring (SRM). The intra- and inter-day precision and accuracy, determined as the coefficient of variation and relative error, respectively, were 11.8% or less. The limit of quantitation was 0.03 ng/ml, and the calibration was linear between 0.03 and 3.0 ng/ml. The method has been used successfully for the measurement of over two thousand human plasma samples from pharmacokinetic clinical trials.

  18. Mass Spectrometric Evidence of Malonaldehyde and 4-Hydroxynonenal Adductions to Radical-Scavenging Soy Peptides

    PubMed Central

    Zhao, Jing; Chen, Jing; Zhu, Haining; Xiong, Youling L.

    2012-01-01

    Antioxidative peptides in food systems are potential targets of lipid oxidation-generated reactive aldehydes, such as malonaldehyde (MDA) and 4-hydroxynonenal (HNE). In this study, covalent modifications on radical-scavenging peptides prepared from soy protein hydrolysate by MDA and HNE were characterized by liquid chromatography–electrospray ionization-mass spectrometry (LC-ESI-MS/MS). MS/MS analyses detected the formation of Schiff base type adducts of MDA on the side chain groups of lysine, histidine, arginine, glutamine, and asparagine residues as well as the N-termini of peptides. MDA also formed a fluorescent product with lysine residues. HNE adducted on lysine residues through Schiff base formation and on histidine, arginine, glutamine, and asparagine residues mainly through Michael addition. In spite of the extensive MDA modification, peptide cross-linking by this potential mechanism was undetectable. PMID:22946674

  19. Gas chromatographic-mass spectrometric method for polycyclic aromatic hydrocarbon analysis in plant biota.

    PubMed

    Meudec, A; Dussauze, J; Jourdin, M; Deslandes, E; Poupart, N

    2006-03-10

    Using gas chromatography-mass spectrometry, a new method was developed for the identification and the quantification of polycyclic aromatic hydrocarbons (PAHs) in plants. This method was particularly optimised for PAH analyses in marine plants such as the halophytic species, Salicornia fragilis Ball et Tutin. The saponification of samples and their clean up by Florisil solid-phase extraction succeeded in eliminating pigments and natural compounds, which may interfere with GC-MS analysis. Moreover, a good recovery of the PAHs studied was obtained with percentages ranging from 88 to 116%. Application to the determination of PAH in a wide range of coastal halophytic plants is presented and validated the efficiency, the accuracy and the reproducibility of this method.

  20. Electrospray ionization mass spectrometric analysis of chemical reactions of dissolution of selenium in strongly basic amines.

    PubMed

    Arakawa, Ryuichi; Sasao, Ai; Sonoda, Noboru

    2005-01-01

    When elemental selenium was added to a strongly basic amine, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), the selenium started to dissolve and the solution turned dark brown. We investigated the chemical reaction of this selenium dissolution process by electrospray ionization mass spectrometry (ESI-MS). The study reveals for the first time that cleavage of Se-Se bonds by the amine initiates the reaction to form molecular Se2, which then abstracts hydrogen from the amine molecule. ESI-MS with the use of a nanospray technique was shown to be a useful tool for studying the dissolution of elements in strongly basic or acidic solvents.

  1. Renewal of an old European Pharmacopoeia method for Terazosin using modeling with mass spectrometric peak tracking.

    PubMed

    Kormány, Róbert; Molnár, Imre; Fekete, Jenő

    2017-02-20

    An older method for terazosin was reworked in order to reduce the analysis time from 90min (2×45min) to below 5min. The method in European Pharmacopoeia (Ph.Eur.) investigates the specified impurities separately. The reason of the different methods is that the retention of two impurities is not adequate in reversed phase, not even with 100% water. Therefore ion-pair-chromatography has to be applied and since that two impurities absorb at low UV-wavelength they had to be analyzed by different method than the other specified impurities. In our new method we could improve the retention with pH elevation using a new type of stationary phases available for high pH applications. Also a detection wavelength could be selected that is appropriate for the detection and quantification of all impurities. The method development is the bottleneck of liquid chromatography even today, when more and more fast chromatographic systems are used. Expert knowledge with intelligent programs is available to reduce the time of method development and offer extra information about the robustness of the separation. Design of Experiments (DoE) for simultaneous optimization of gradient time (tG), temperature (T) and ternary eluent composition (tC) requires 12 experiments. A good alternative way to identify a certain peak in different chromatograms is the molecular mass of the compound, due to its high specificity. Liquid Chromatography-Mass Spectrometry (LC-MS) is now a routine technique and increasingly available in laboratories. In our experiment for the resolution- and retention modeling the DryLab4 method development software (Version 4.2) was used. In recent versions of the software the use of (m/z)-MS-data is possible along the UV-peak-area-tracking technology. The modelled and measured chromatograms showed excellent correlations. The average retention time deviations were ca. 0.5s and there was no difference between the predicted and measured Rs,crit -values.

  2. Honeybee venom proteome profile of queens and winter bees as determined by a mass spectrometric approach.

    PubMed

    Danneels, Ellen L; Van Vaerenbergh, Matthias; Debyser, Griet; Devreese, Bart; de Graaf, Dirk C

    2015-10-30

    Venoms of invertebrates contain an enormous diversity of proteins, peptides, and other classes of substances. Insect venoms are characterized by a large interspecific variation resulting in extended lists of venom compounds. The venom composition of several hymenopterans also shows different intraspecific variation. For instance, venom from different honeybee castes, more specifically queens and workers, shows quantitative and qualitative variation, while the environment, like seasonal changes, also proves to be an important factor. The present study aimed at an in-depth analysis of the intraspecific variation in the honeybee venom proteome. In summer workers, the recent list of venom proteins resulted from merging combinatorial peptide ligand library sample pretreatment and targeted tandem mass spectrometry realized with a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS/MS). Now, the same technique was used to determine the venom proteome of queens and winter bees, enabling us to compare it with that of summer bees. In total, 34 putative venom toxins were found, of which two were never described in honeybee venoms before. Venom from winter workers did not contain toxins that were not present in queens or summer workers, while winter worker venom lacked the allergen Api m 12, also known as vitellogenin. Venom from queen bees, on the other hand, was lacking six of the 34 venom toxins compared to worker bees, while it contained two new venom toxins, in particularly serine proteinase stubble and antithrombin-III. Although people are hardly stung by honeybees during winter or by queen bees, these newly identified toxins should be taken into account in the characterization of a putative allergic response against Apis mellifera stings.

  3. Honeybee Venom Proteome Profile of Queens and Winter Bees as Determined by a Mass Spectrometric Approach

    PubMed Central

    Danneels, Ellen L.; Van Vaerenbergh, Matthias; Debyser, Griet; Devreese, Bart; de Graaf, Dirk C.

    2015-01-01

    Venoms of invertebrates contain an enormous diversity of proteins, peptides, and other classes of substances. Insect venoms are characterized by a large interspecific variation resulting in extended lists of venom compounds. The venom composition of several hymenopterans also shows different intraspecific variation. For instance, venom from different honeybee castes, more specifically queens and workers, shows quantitative and qualitative variation, while the environment, like seasonal changes, also proves to be an important factor. The present study aimed at an in-depth analysis of the intraspecific variation in the honeybee venom proteome. In summer workers, the recent list of venom proteins resulted from merging combinatorial peptide ligand library sample pretreatment and targeted tandem mass spectrometry realized with a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS/MS). Now, the same technique was used to determine the venom proteome of queens and winter bees, enabling us to compare it with that of summer bees. In total, 34 putative venom toxins were found, of which two were never described in honeybee venoms before. Venom from winter workers did not contain toxins that were not present in queens or summer workers, while winter worker venom lacked the allergen Api m 12, also known as vitellogenin. Venom from queen bees, on the other hand, was lacking six of the 34 venom toxins compared to worker bees, while it contained two new venom toxins, in particularly serine proteinase stubble and antithrombin-III. Although people are hardly stung by honeybees during winter or by queen bees, these newly identified toxins should be taken into account in the characterization of a putative allergic response against Apis mellifera stings. PMID:26529016

  4. Comprehensive Characterization of Atmospheric Organic Carbon using Multiple High-Resolution Mass Spectrometric Instruments

    NASA Astrophysics Data System (ADS)

    Kroll, J. H.; Hunter, J. F.; Isaacman-VanWertz, G. A.

    2015-12-01

    Accurate modeling of major atmospheric chemical processes (oxidant cycling, aerosol formation, etc.) requires understanding the identity, chemistry, and lifecycle (emission, reaction, and deposition) of atmospheric organic species. Such an understanding is generally limited by the wide diversity in chemical structure, properties, and reactivity of atmospheric organics, posing major challenges in detection and quantification. However the last several years have seen the development of several new techniques for the measurement of a wide range of carbon-containing compounds, including low-volatility, oxidized species that have traditionally been difficult to measure. Many of these new techniques are based on high-resolution mass spectrometry, enabling the unambiguous identification of individual ions, and hence the elemental ratios and carbon oxidation state of the organic species; most also provide information on volatility and/or carbon number distributions of the molecular species. While a single instrument can generally measure only species of a particular class (occupying a localized region of "chemical space"), here we show that the combined measurements from multiple instruments can provide a comprehensive picture of the chemical composition of the entire organic mixture. From these combined measurements, the organic species can be described not only in terms of organic carbon mass but also in terms of distributions of key ensemble properties (such as oxidation state and volatility), and thus can be used to populate and constrain the various reduced-dimensionality chemical spaces that have been put forth as frameworks for describing atmospheric organic chemistry. We apply this general measurement approach both to field data, providing information on ambient organic species, and to laboratory (chamber) studies, providing insight into the chemical transformations that organic species undergo upon atmospheric oxidation.

  5. Mass spectrometric approaches for the identification of anthracycline analogs produced by actinobacteria.

    PubMed

    Bauermeister, Anelize; Zucchi, Tiago Domingues; Moraes, Luiz Alberto Beraldo

    2016-06-01

    Anthracyclines are a well-known chemical class produced by actinobacteria used effectively in cancer treatment; however, these compounds are usually produced in few amounts because of being toxic against their producers. In this work, we successfully explored the mass spectrometry versatility to detect 18 anthracyclines in microbial crude extract. From collision-induced dissociation and nuclear magnetic resonance spectra, we proposed structures for five new and identified three more anthracyclines already described in the literature, nocardicyclins A and B and nothramicin. One new compound 8 (4-[4-(dimethylamino)-5-hydroxy-4,6-dimethyloxan-2-yl]oxy-2,5,7,12-tetrahydroxy-3,10-dimethoxy-2-methyl-3,4-dihydrotetracene-1,6,11-trione) was isolated and had its structure confirmed by (1) H nuclear magnetic resonance. The anthracyclines identified in this work show an interesting aminoglycoside, poorly found in natural products, 3-methyl-rhodosamine and derivatives. This fact encouraged to develop a focused method to identify compounds with aminoglycosides (rhodosamine, m/z 158; 3-methyl-rhodosamine, m/z 172; 4'-O-acethyl-3-C-methyl-rhodosamine, m/z 214). This method allowed the detection of four more anthracyclines. This focused method can also be applied in the search of these aminoglycosides in other microbial crude extracts. Additionally, it was observed that nocardicyclin A, nothramicin and compound 8 were able to interact to DNA through a DNA-binding study by mass spectrometry, showing its potential as anticancer drugs. Copyright © 2016 John Wiley & Sons, Ltd.

  6. Expanding analytical options in sports drug testing: Mass spectrometric detection of prohibited substances in exhaled breath.

    PubMed

    Thevis, Mario; Krug, Oliver; Geyer, Hans; Schänzer, Wilhelm

    2017-08-15

    Continuously refining and advancing the strategies and methods employed in sports drug testing is critical for efficient doping controls. Besides improving and expanding the spectrum of target analytes, alternative test matrices have warranted in-depth evaluation as they commonly allow for minimal-/non-invasive and non-intrusive sample collection. In this study, the potential of exhaled breath (EB) as doping control specimen was assessed. EB collection devices employing a non-woven electret-based air filter unit were used to generate test specimens, simulating a potential future application in doping controls. A multi-analyte sports drug testing approach configured for a subset of 12 model compounds that represent specific classes of substances prohibited in sports (anabolic agents, hormone and metabolic modulators, stimulants, and beta-blockers) was established using unispray liquid chromatography/tandem mass spectrometry (LC/MS/MS) and applied to spiked and elimination study EB samples. The test method was characterized concerning specificity, assay imprecision, and limits of detection. The EB collection device allowed for retaining and extracting all selected model compounds from the EB aerosol. Following elution and concentration, LC/MS/MS analysis enabled detection limits between 5 and 100 pg/filter and imprecisions ranging from 3% to 20% for the 12 selected model compounds. By means of EB samples from patients and participants of administration studies, the elimination of relevant compounds and, thus, their traceability in EB for doping control purposes, was investigated. Besides stimulants such as methylhexaneamine and pseudoephedrine, also the anabolic-androgenic steroid dehydrochloromethyltestosterone, the metabolic modulator meldonium, and the beta-blocker bisoprolol was detected in exhaled breath. The EB aerosol has provided a promising proof-of-concept suggesting the expansion of this testing strategy as a complement to currently utilized sports drug

  7. Amyloid neuropathy type is distinguished by mass spectrometric based proteomic analysis of nerve tissue

    PubMed Central

    Klein, Christopher J.; Vrana, Julie A.; Theis, Jason D.; Dyck, Peter J.; Dyck, P. James B.; Spinner, Robert J.; Mauermann, Michelle L; Bergen, H. Robert; Zeldenrust, Steven R.; Dogan, Ahmet

    2011-01-01

    Objective To determine specific type of amyloid from nerve biopsies using laser microdissection (LMD) and mass spectrometry (MS) based proteomic analysis. Methods Twenty one nerve biopsies (17 sural, 3 sciatic, 1 root amyloidoma) infiltrated by amyloid were studied. Immunohistochemical subtyping was unable to determine the specific amyloid for these 21 cases, but the clinical diagnosis was made based on additional testing. Clinical diagnosis was made through evaluation of serum monoclonal proteins, biopsy of bone marrow for acquired monoclonal immunoglobulin light-chain amyloidosis (AL) and kindred evaluations with DNA sequencing of transthyretin (TTR) and gelsolin (GSN). Our study included 8 cases of AL-type amyloidosis, 11 cases of TTR amyloidosis (3 Val30Met, 2 Val32Ala, 2 Thr60Ala, 1Ala109Ser, 1 Phe64Leu, 1 Ala97Ser, 1 not sequenced), and 2 cases of gelsolin amyloidosis (1 Asp187Asn, 1 not sequenced). One TTR and one gelsolin amyloidosis patients with no specific mutation identified were diagnosed based on the genetic confirmation in their first degree relative. Congophilic proteins in the tissues of these 21 cases were laser microdissected, digested into tryptic peptides and analyzed utilizing liquid chromatography electrospray tandem mass spectrometry. Identified proteins were reviewed using bioinformatics tools with interpreters blinded to clinical information. Results Specific types of amyloid were accurately detected by LMD/MS in all cases (8 AL-type, 2 gelsolin, and 11 transthyretin). Incidental serum monoclonal proteins did not interfere with detection of TTR amyloidosis in two patients. Additionally, specific TTR mutations were identified in ten cases by LMD/MS. Serum amyloid P-component and apolipoprotein E proteins were commonly found among all cases. Conclusions Proteomic analysis of nerve tissue using LMD/MS distinguishes specific types of amyloid independent of clinical information. This new proteomic approach will enhance both diagnostic and

  8. [On-line solid phase extraction for desalting coupled with mass spectrometric analysis].

    PubMed

    Chen, Jing; Liu, Zhaojin; Dai, Zhenyu; An, Baochao; Xu, Qun; Zhang, Xiangmin

    2013-09-01

    The work shown here describes a simple, fast and effective on-line solid phase extraction (on-line SPE) method for facilitative high-throughput sample desalting before the detection of mass spectrometry (MS) or liquid chromatography-mass spectrometry (LC-MS). This method includes single SPE column mode and dual SPE column mode. It accomplishes the on-line desalting with an Ultimate 3000 HPLC system equipped with a dual pump system (loading pump/analytical pump), an autosampler, a column oven equipped with a 2p-10p valve, controlled by a chromatography data system. In the single SPE column mode, sample loading and desalting were performed on the SPE column using the loading pump. The analytes were retained on the SPE column, and the salt in the sample solution was flushed out of the SPE column. After desalting, the retained analytes were eluted from the SPE column with the analytical pump. In the dual SPE column mode, two same SPE columns were used. Firstly, the sample loading and desalting were performed on the SPE column 1. The analytes were retained and the salt was flushed out. After desalting on the SPE column 1, the sample loading and desalting were performed on the SPE column 2. Meanwhile, the retained analytes were eluted from the SPE column 1 with the analytical pump. As both of the processes on the SPE columns 1 and 2 described above completed, the sample loading and desalting on the SPE column 1, and the elution of the analytes from the SPE column 2 started again. As the SPE columns 1 and 2 worked in turn, the on-line SPE desalting system was efficient. The eluted analytes from the SPE columns may be determined by MS directly, or separated on the analytical column and then determined by MS/UV.

  9. Use of flow injection mass spectrometric fingerprinting and chemometrics for differentiation of three black cohosh species

    NASA Astrophysics Data System (ADS)

    Huang, Huilian; Sun, Jianghao; McCoy, Joe-Ann; Zhong, Haiyan; Fletcher, Edward J.; Harnly, James; Chen, Pei

    2015-03-01

    Flow injection mass spectrometry (FIMS) was used to provide chemical fingerprints of black cohosh (Actaea racemosa L.) in a manner of minutes by omitting the separation step. This method has proven to be a powerful tool for botanical authentication and in this study it was used to distinguish between three Actaea species prior to a more detailed chemical analysis using ultra high-performance liquid chromatography high-resolution mass spectrometry (UHPLC-HRMS). Black cohosh has become increasingly popular as a dietary supplement in the United States for the treatment of symptoms related to menopause. However, it has been known to be adulterated with the Asian Actaea dahurica (Turcz. ex Fisch. & C.A.Mey.) Franch. species (syn. Cimicifuga dahurica (Turcz.) Maxim). Existing methods for identification of black cohosh and differentiation of Actaea species are usually lengthy, laborious, and lack robustness, often based on the comparison of a few pre-selected components. Chemical fingerprints were obtained for 77 black cohosh samples and their related species using FIMS in the negative ion mode. The analysis time for each sample was less than 2 min. All data were processed using principal component analysis (PCA). FIMS fingerprints could readily differentiate all three species. Representative samples from each of the three species were further examined using UHPLC-MS to provide detailed profiles of the chemical differences between the three species and were compared to the PCA loadings. This study demonstrates a simple, fast, and easy analytical method that can be used to differentiate A. racemosa, Actaea podocarpa, and A. dahurica.

  10. Sampling and mass spectrometric analytical methods for five antineoplastic drugs in the healthcare environment

    PubMed Central

    Pretty, Jack R; Connor, Thomas H; Spasojevic, Ivan; Kurtz, Kristine S; McLaurin, Jeffrey L; B’Hymer, Clayton; Debord, D Gayle

    2015-01-01

    Context Healthcare worker exposure to antineoplastic drugs continues to be reported despite safe handling guidelines published by several groups. Sensitive sampling and analytical methods are needed so that occupational safety and health professionals may accurately assess environmental and biological exposure to these drugs in the workplace. Objective To develop liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) analytical methods for measuring five antineoplastic drugs in samples from the work environment, and to apply these methods in validating sampling methodology. A single method for quantifying several widely used agents would decrease the number of samples required for method development, lower cost, and time of analysis. Methods for measuring these drugs in workers’ urine would also be useful in monitoring personal exposure levels. Results LC-MS/MS methods were developed for individual analysis of five antineoplastic drugs in wipe and air sample media projected for use in field sampling: cyclophosphamide, ifosfamide, paclitaxel, doxorubicin, and 5-fluorouracil. Cyclophosphamide, ifosfamide, and paclitaxel were also measured simultaneously in some stages of the work. Extraction methods for air and wipe samples were developed and tested using the aforementioned analytical methods. Good recoveries from the candidate air and wipe sample media for most of the compounds, and variable recoveries for test wipe samples depending on the surface under study, were observed. Alternate LC-MS/MS methods were also developed to detect cyclophosphamide and paclitaxel in urine samples. Conclusions The sampling and analytical methods were suitable for determining worker exposure to antineoplastics via surface and breathing zone contamination in projected surveys of healthcare settings. PMID:21183556

  11. Sampling and mass spectrometric analytical methods for five antineoplastic drugs in the healthcare environment.

    PubMed

    Pretty, Jack R; Connor, Thomas H; Spasojevic, Ivan; Kurtz, Kristine S; McLaurin, Jeffrey L; B'Hymer, Clayton; Debord, D Gayle

    2012-03-01

    Healthcare worker exposure to antineoplastic drugs continues to be reported despite safe handling guidelines published by several groups. Sensitive sampling and analytical methods are needed so that occupational safety and health professionals may accurately assess environmental and biological exposure to these drugs in the workplace. To develop liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) analytical methods for measuring five antineoplastic drugs in samples from the work environment, and to apply these methods in validating sampling methodology. A single method for quantifying several widely used agents would decrease the number of samples required for method development, lower cost, and time of analysis. for measuring these drugs in workers' urine would also be useful in monitoring personal exposure levels. LC-MS/MS methods were developed for individual analysis of five antineoplastic drugs in wipe and air sample media projected for use in field sampling: cyclophosphamide, ifosfamide, paclitaxel, doxorubicin, and 5-fluorouracil. Cyclophosphamide, ifosfamide, and paclitaxel were also measured simultaneously in some stages of the work. Extraction methods for air and wipe samples were developed and tested using the aforementioned analytical methods. Good recoveries from the candidate air and wipe sample media for most of the compounds, and variable recoveries for test wipe samples depending on the surface under study, were observed. Alternate LC-MS/MS methods were also developed to detect cyclophosphamide and paclitaxel in urine samples. The sampling and analytical methods were suitable for determining worker exposure to antineoplastics via surface and breathing zone contamination in projected surveys of healthcare settings.

  12. Mass spectrometric analysis of activity-dependent changes of neuropeptide profile in the snail, Helix pomatia.

    PubMed

    Pirger, Z; Lubics, A; Reglodi, D; Laszlo, Z; Mark, L; Kiss, T

    2010-12-01

    Terrestrial snails are able to transform themselves into inactivity ceasing their behavioral activity under unfavorable environmental conditions. In the present study, we report on the activity-dependent changes of the peptide and/or polypeptide profile in the brain and hemolymph of the snail, Helix pomatia, using MALDI TOF and quadrupole mass spectrometry. The present data indicate that the snails respond to low temperature by increasing or decreasing the output of selected peptides. Average mass spectra of the brain and hemolymph revealed numerous peaks predominantly present during the active state (19 and 10 peptides/polypeptides, respectively), while others were observed only during hibernation (11 and 13). However, there were peptides and/or polypeptides or their fragments present irrespective of the activity states (49 and 18). The intensity of fourteen peaks that correspond to previously identified neuropeptides varied in the brain of active snails compared to those of hibernating animals. Among those the intensity of eight peptides increased significantly in active animals while in hibernated animals the intensity of another six peptides increased significantly. A new peptide or peptide fragment at m/z 1110.7 was identified in a brain of the snail with the following suggested amino acid sequence: GSGASGSMPATTS. This peptide was found to be more abundant in active animals because the intensity of the peptide was significantly higher compared to hibernating animals. In summary, our results revealed substantial differences in the peptide/polypeptide profile of the brain and hemolymph of active and hibernating snails suggesting a possible contribution of peptides in the process of hibernation. Copyright © 2010 Elsevier Ltd. All rights reserved.

  13. Expression, purification and mass spectrometric analysis of LIM mineralization protein-1 in human lung epithelial cells.

    PubMed

    Sangadala, Sreedhara; Titus, Louisa; Boden, Scott D

    2008-11-01

    LIM mineralization protein-1 (LMP-1) is a novel osteoinductive protein that has been cloned and shown to induce bone formation both in vitro and in vivo. Detection and evaluation of the possible presence of carbohydrate structures in LMP-1 is an important regulatory consideration for the therapeutic use of recombinantly expressed protein. The sequence of LMP-1 contains a highly conserved N-terminal PDZ domain and three C-terminal LIM domains. The sequence analysis of LMP-1 predicts two potential N-glycosylation sites and several O-glycosylation sites. Here, we report the cloning and overexpression of LMP-1 in human lung carcinoma (A549) cells. Even though our group already reported the sequence of LMP-1 cDNA, we undertook this work to clarify whether or not the overexpressed protein undergoes any glycosylation in vivo. The expressed full-length recombinant protein was purified and subjected to chemical analysis and internal sequencing. The absence of any hexosamines (N-acetyl glucosamine or N-acetyl galactosamine) in chemical composition analysis of LMP-1 protein revealed that there is little or no post-translational glycosylation of the LMP-1 polypeptide in lung carcinoma cells (A549). We performed in-gel trypsin digestion on purified LMP-1, and the resulting peptide digests were analyzed further using matrix-assisted laser desorption and ionization mass spectrometry for peptide mass finger printing, which produced several exact matches with the corresponding LMP-1 peptides. Separation by high performance liquid chromatography and purification of the desired peptides followed by N-terminal sequencing resulted in many exact LMP-1 matches for several purified peptides, thus establishing the identity of the purified protein as LMP-1.

  14. Adduct formation in liquid chromatography-triple quadrupole mass spectrometric measurement of bryostatin 1.

    PubMed

    Nelson, Thomas J; Sen, Abhik; Alkon, Daniel L; Sun, Miao-Kun

    2014-01-01

    Bryostatin 1, a potential anti-Alzheimer drug, is effective at subnanomolar concentrations. Measurement is complicated by the formation of low m/z degradation products and the formation of adducts with various cations, which make accurate quantitation difficult. Adduct