Mass Spectrometry (mass + spectrometry)

Distribution by Scientific Domains
Distribution within Chemistry

Kinds of Mass Spectrometry

  • accelerator mass spectrometry
  • atmospheric pressure chemical ionization mass spectrometry
  • atmospheric pressure chemical ionization tandem mass spectrometry
  • atmospheric pressure photoionization mass spectrometry
  • atom bombardment mass spectrometry
  • bombardment mass spectrometry
  • chemical ionization mass spectrometry
  • chemical ionization tandem mass spectrometry
  • chromatography electrospray ionization mass spectrometry
  • chromatography electrospray ionization tandem mass spectrometry
  • chromatography ion trap mass spectrometry
  • chromatography ionisation mass spectrometry
  • chromatography ionization mass spectrometry
  • chromatography ionization tandem mass spectrometry
  • chromatography mass spectrometry
  • chromatography ratio mass spectrometry
  • chromatography tandem mass spectrometry
  • chromatography time-of-flight mass spectrometry
  • chromatography-combustion-isotope ratio mass spectrometry
  • chromatography-tandem mass spectrometry
  • cyclotron resonance mass spectrometry
  • desorption electrospray ionization mass spectrometry
  • desorption ionization time-of-flight mass spectrometry
  • desorption mass spectrometry
  • desorption time-of-flight mass spectrometry
  • dilution mass spectrometry
  • dissociation tandem mass spectrometry
  • electron ionization mass spectrometry
  • electrospray ion trap mass spectrometry
  • electrospray ionisation mass spectrometry
  • electrospray ionisation tandem mass spectrometry
  • electrospray ionization fourier transform ion cyclotron resonance mass spectrometry
  • electrospray ionization mass spectrometry
  • electrospray ionization tandem mass spectrometry
  • electrospray ionization time-of-flight mass spectrometry
  • electrospray mass spectrometry
  • electrospray tandem mass spectrometry
  • electrospray-ionization mass spectrometry
  • esi mass spectrometry
  • fab mass spectrometry
  • fast atom bombardment mass spectrometry
  • flight mass spectrometry
  • flow tube mass spectrometry
  • fourier transform ion cyclotron resonance mass spectrometry
  • fourier transform mass spectrometry
  • fourier-transform ion cyclotron resonance mass spectrometry
  • gas chromatography mass spectrometry
  • gas chromatography ratio mass spectrometry
  • gas chromatography-combustion-isotope ratio mass spectrometry
  • gas mass spectrometry
  • high-performance liquid chromatography ionization mass spectrometry
  • high-performance liquid chromatography ionization tandem mass spectrometry
  • high-performance liquid mass spectrometry
  • high-performance liquid tandem mass spectrometry
  • high-resolution mass spectrometry
  • imaging mass spectrometry
  • inlet mass spectrometry
  • introduction mass spectrometry
  • ion cyclotron resonance mass spectrometry
  • ion flow tube mass spectrometry
  • ion mass spectrometry
  • ion mobility mass spectrometry
  • ion trap mass spectrometry
  • ion trap tandem mass spectrometry
  • ion-trap mass spectrometry
  • ion-trap tandem mass spectrometry
  • ionisation mass spectrometry
  • ionisation tandem mass spectrometry
  • ionization fourier transform ion cyclotron resonance mass spectrometry
  • ionization fourier transform mass spectrometry
  • ionization imaging mass spectrometry
  • ionization ion trap mass spectrometry
  • ionization mass spectrometry
  • ionization quadrupole time-of-flight tandem mass spectrometry
  • ionization tandem mass spectrometry
  • ionization time-of-flight mass spectrometry
  • ionization-tandem mass spectrometry
  • isotope dilution mass spectrometry
  • isotope ratio mass spectrometry
  • laser desorption ionization time-of-flight mass spectrometry
  • laser desorption mass spectrometry
  • laser desorption time-of-flight mass spectrometry
  • laser ionization mass spectrometry
  • laser ionization time-of-flight mass spectrometry
  • liquid chromatography electrospray ionization mass spectrometry
  • liquid chromatography electrospray ionization tandem mass spectrometry
  • liquid chromatography ion trap mass spectrometry
  • liquid chromatography ionisation mass spectrometry
  • liquid chromatography ionization mass spectrometry
  • liquid chromatography ionization tandem mass spectrometry
  • liquid chromatography mass spectrometry
  • liquid chromatography tandem mass spectrometry
  • liquid chromatography time-of-flight mass spectrometry
  • liquid chromatography-tandem mass spectrometry
  • liquid ion trap mass spectrometry
  • liquid mass spectrometry
  • liquid secondary ion mass spectrometry
  • liquid tandem mass spectrometry
  • maldi mass spectrometry
  • maldi-tof mass spectrometry
  • matrix-assisted laser desorption ionization time-of-flight mass spectrometry
  • matrix-assisted laser desorption time-of-flight mass spectrometry
  • matrix-assisted laser ionization mass spectrometry
  • matrix-assisted laser ionization time-of-flight mass spectrometry
  • membrane inlet mass spectrometry
  • membrane introduction mass spectrometry
  • mobility mass spectrometry
  • multiple-stage mass spectrometry
  • nano-electrospray ionization mass spectrometry
  • negative electrospray ionization tandem mass spectrometry
  • negative ion mass spectrometry
  • photoionization mass spectrometry
  • plasma mass spectrometry
  • pressure chemical ionization mass spectrometry
  • pressure chemical ionization tandem mass spectrometry
  • pressure photoionization mass spectrometry
  • probe mass spectrometry
  • quadrupole ion trap mass spectrometry
  • quadrupole mass spectrometry
  • quadrupole time-of-flight mass spectrometry
  • quadrupole time-of-flight tandem mass spectrometry
  • quantitative mass spectrometry
  • radical probe mass spectrometry
  • ratio mass spectrometry
  • resolution mass spectrometry
  • resonance mass spectrometry
  • secondary ion mass spectrometry
  • selected ion flow tube mass spectrometry
  • sensitive liquid tandem mass spectrometry
  • silicon mass spectrometry
  • tandem mass spectrometry
  • time-of-flight mass spectrometry
  • time-of-flight secondary ion mass spectrometry
  • time-of-flight tandem mass spectrometry
  • tof mass spectrometry
  • transform ion cyclotron resonance mass spectrometry
  • transform mass spectrometry
  • trap mass spectrometry
  • trap tandem mass spectrometry
  • triple quadrupole mass spectrometry
  • tube mass spectrometry

  • Terms modified by Mass Spectrometry

  • mass spectrometry analysis
  • mass spectrometry approach
  • mass spectrometry data
  • mass spectrometry detection
  • mass spectrometry determination
  • mass spectrometry experiment
  • mass spectrometry imaging
  • mass spectrometry measurement
  • mass spectrometry method
  • mass spectrometry methods
  • mass spectrometry study
  • mass spectrometry system
  • mass spectrometry technique
  • mass spectrometry techniques
  • mass spectrometry technology

  • Selected Abstracts

    SPME/GC/MS and sensory flavour profile analysis for estimation of authenticity of thyme honey

    Demet Manna
    Summary Volatiles of six commercially obtained thyme honey samples and a pure thyme honey sample were extracted and analysed by Solid phase micro extraction (SPME)/Gas chromatography (GC)/Mass spectrometry (MS) procedure. Excess amount of volatiles such as thymol (trace) and carvacrole (0.66%) that originate from thyme plants indicated adulteration by thyme essential oil in one of the commercial samples. Sensory flavour profile analysis showed that the flavour of pure thyme honey sample consisted of: sweet, honey, lilac, bitter almond, thyme, violet, waxy, sour, ginger, caramel and rose characters. Adulterated honey was detected to be the sweetest sample involving intense thyme flavour without honey character. 3,4,5-Trimethoxybenzaldehyde which is a volatile not found in other unifloral honeys, seems to be a possible marker, but further studies with certified thyme honey samples are necessary in order to confirm the utility of this compound in estimation of authenticity. [source]

    In vitro biotransformation of anabolic steroids in canines

    Forensic drug testing of anabolic steroids in racing animals is required because of the potential for steroid abuse. Often when the metabolic products of an administered compound have not been identified, the analysis and verification of the administered compound is difficult. The objective of this study was to qualitatively identify the in vitro phase I biotransformation products of anabolic steroids that have a high potential for abuse in canines. The investigated steroids included testosterone, methyltestosterone, mibolerone and boldenone. Steroid biotransformation products were generated using beagle liver microsomes and analysed by high performance liquid chromatography (HPLC)/mass spectrometry (MS) with an electrospray ionization source. Characterization of steroid metabolites was based on HPLC retention, UV and mass spectra. The major testosterone metabolites were identified as androstenedione and 6,- and 16,-hydroxytestosterone. 6,-Hydroxymethyltestosterone was identified as a major metabolite in the methyltestosterone microsomal incubations. Several mibolerone metabolites were identified as monohydroxylated mibolerones as well as an oxidized mibolerone metabolite. Boldenone metabolites were identified as monohydroxylated boldenones, oxidized boldenone, and testosterone. This information should assist in the determination of anabolic steroid use in canines through the correlation of the urinary metabolites to the administered drug. [source]

    Direct determination of endogenous melatonin in human saliva by column-switching semi-microcolumn liquid chromatography/mass spectrometry with on-line analyte enrichment

    Akira Motoyama
    An analytical method that enables direct and sensitive determination of endogenous melatonin (MLT) in human saliva was developed by means of column-switching semi-microcolumn liquid chromatography (i.d.: 1,2,mm)/mass spectrometry (LC/MS). The system allows direct injection analysis of a 400-,L aliquot of saliva with minimal sample pretreatment (internal standard (IS) addition and vortex mixing) and a relatively short run-time (10,min). The system consists of three columns to attain large volume injection and on-line analyte enrichment. A pre-column packed with a silica-based mixed-functional C8 (4.0,mm i.d.,×,20,mm) was used for on-line sample cleanup. MLT and an IS, the d7 isomer of MLT (d7-MLT), were heart-cut by valve switching and enriched at the top of the intermediate trapping column packed with a silica-based C18 (4.0,mm i.d.,×,10,mm). Subsequently, the analytes were backflushed into a semi-micro C18 silica column (2.0,mm i.d.,×,150 mm) for the final separation. MLT and IS were ascertained by positive electrospray ionization and selected ion monitoring (SIM). MLT was monitored based on its fragment ion at m/z 174.1 by in-source collision-induced dissociation (CID). The validation of this method revealed a detection limit of 2.5,pg,mL,1 at a signal-to-noise (S/N) ratio of 5. The linearity of the method was established in the ranges 5,250 and 100,2500,pg,mL,1 with a coefficient of determination of greater than 0.998. Accuracies, evaluated at five levels in the range 5,1000,pg,mL,1, were between 81 and 108% with a relative standard deviation (RSD) ranging from 1.3,20%. The method was successfully applied for the endogenous saliva MLT monitoring of two healthy subjects. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    Identification and analysis of 2-chloro-6-methylphenol, 2,6-dichlorophenol and indole: causes of taints and off-flavours in wines

    Abstract Background and Aims:, The aim of this study was to determine the cause of taints and off-flavours in a number of commercial wines and to develop methods for quantitative analysis of the compounds responsible. Methods and Results:, Three compounds, 2-chloro-6-methylphenol (i.e. 6-chloro- ortho -cresol), 2,6-dichlorophenol and indole, were identified by gas chromatography (GC)/mass spectrometry (MS)/olfactometry as causes of taints or off-flavours in the wines. New methods for quantitative analysis of these three compounds, as well as some other chloro- and bromophenols were developed. The methods employed GC/MS and stable isotope dilution analysis, and confirmed the presence of 2-chloro-6-methylphenol, 2,6-dichlorophenol and indole in some wines at concentrations well above their odour and taste detection thresholds. Conclusions:, 2-Chloro-6-methylphenol, 2,6-dichlorophenol and indole were confirmed as causes of taints and off-flavours in commercial wines. Significance of the Study:, The development of new analytical methods will make it possible to determine whether chlorophenol (and perhaps also bromophenol) taint in wine is more widespread than previously recognised. Similarly, the simple, rapid and accurate method for quantifying indole in wine will allow large numbers of wine and ferment samples to be studied to determine those factors that can result in unacceptably high concentrations in commercial wines. [source]

    Private channel: a single unusual compound assures specific pollinator attraction in Ficus semicordata

    FUNCTIONAL ECOLOGY, Issue 5 2009
    Chun Chen
    Summary 1.,Floral scents have been suggested to play a key role in the obligate pollination mutualism between figs and fig wasps. However, few studies have determined whether pollinator-attractive compounds could alone assure species-specificity (,private channel'), or whether specificity is mediated by more complex ,floral filters', of which scent is only one component. 2.,We examined changes in the floral volatile compounds of Ficus semicordata, a dioecious fig species, during and after pollination using headspace collection and compound identification by Gas Chromatography/Mass Spectrometry (GC/MS). One benzenoid compound, 4-methylanisole, was strongly predominant (94,98%) among the volatile compounds emitted by both male and female receptive figs of F. semicordata, whereas it was totally absent in the volatiles emitted by figs 4 days after pollination, as well as in receptive-stage volatiles emitted by two other sympatric fig species, Ficus racemosa and Ficus hispida. 3.,Bioassays using the specific pollinator of F. semicordata, Ceratosolen gravelyi, in a Y-tube olfactometer showed that 4-methylanisole was attractive to C. gravelyi in a wide range of concentrations (from 1·22 × 10,2 ng/100 ,L to 1·22 × 106ng/100,L). Moreover, chemical blends lacking 4-methylanisole were unattractive to C. gravelyi. These non-active odour sources included volatile compounds emitted by receptive figs of the two other sympatric fig species and volatiles of F. semicordata post-pollination figs. 4.,All these results suggest that 4-methylanisole is the main signal compound in the floral scent of F. semicordata that attracts its obligate pollinator to the host figs at the precise stage required for pollination and oviposition. Furthermore, the high proportion of 4-methylanisole in the odours of receptive figs of both sexes was consistent with the hypothesis of chemical mimicry in dioecious figs. 5.,A simple signal comprised of one compound that is unusual among Ficus and that is an infrequent, usually minor, component of other floral odours, may thus function as a private channel in this specialized obligate mutualism. [source]

    N -Cyanomethyl- N -Methyl-1-(3,,4,-methylenedioxyphenyl)-2-propylamine: An MDMA Manufacturing By-Product

    Helen Salouros B.Sc.
    Abstract:, This paper describes the structural elucidation of a compound produced during the synthesis of 3,4-methylenedioxymethylamphetamine (MDMA) via the reductive amination of 3,4-methylenedioxyphenyl-2-propanone (3,4-MDP-2-P) with methylamine and sodium cyanoborohydride. The compound was isolated from MDMA by column chromatography, proton and carbon nuclear magnetic resonance spectroscopy, LC/mass spectrometry, and total synthesis were used to identify the compound as N -cyanomethyl- N -methyl-1-(3,,4,-methylenedioxyphenyl)-2-propylamine. This compound has been identified as a potential synthetic route marker for the reductive amination of 3,4-MDP-2-P with methylamine and sodium cyanoborohydride and as such it should prove valuable to forensic scientists engaged in profiling illicit drugs. Profiling MDMA can provide useful information to law enforcement agencies relating to synthetic route, precursor chemicals and reagents employed and may be used for comparative analyses of different drug seizures. This paper also describes the structural elucidation of the analogous methylamphetamine synthetic route marker compound, N -cyanomethyl- N -methyl-1-phenyl-2-propylamine, produced during the reductive amination of phenyl-2-propanone using methylamine and sodium cyanoborohydride. [source]


    ARCHAEOMETRY, Issue 6 2009
    F. J. M. RUTTEN
    Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been used, for the first time, for the characterization of opaque ancient glasses. Isotope-specific chemical imaging with sub-micron resolution enabled the separate analysis of opacifiying inclusions and the surrounding glass matrix. Phase identification has been demonstrated and quantification of the matrix composition has been investigated by use of Corning Glass Standard B as a model. Trace element detection limits are typically in the range 0.5,5.0 ppm atomic,in favourable cases down to 0.01 ppm. For the analysis of inclusions in particular, this has the potential to provide new information of use in establishing provenance and trade routes by ,fingerprinting' as well as the investigation of manufacturing techniques, as demonstrated by comparisons between glasses and with EDX data from the same samples. [source]


    ARCHAEOMETRY, Issue 4 2009
    C. MATHE
    Four Nabataean samples collected in some of the monumental tombs of Madâ'in Sâlih, ancient Hegra, in Saudi Arabia, have been studied by gas chromatography coupled with mass spectrometry. These samples are textile fragments that are either covered with a black layer or bound together with some black amorphous substance. Fatty acids and triterpenoic compounds were detected. Eight triterpenic compounds were identified: ursa-9(11),12-dien-3-ol, ursa-9(11),12-dien-3-one, olean-9(11),12-dien-3,-ol, ,-amyrone, ,-amyrin, ,-amyrone, ,-amyrin and lupeol. The resinous chemical composition and these pentacyclic alcohols, in considerable proportion, indicate a resin of the Burseraceae family, possibly of the genus Canarium. [source]

    A Comparison of Membrane Inlet Mass Spectrometry and Nitric Oxide (NO) Electrode Techniques to Detect NO in Aqueous Solution

    ELECTROANALYSIS, Issue 4 2010
    Chingkuang Tu
    Abstract The NO electrode and membrane inlet mass spectrometry (MIMS) have the advantage of being sensitive, direct, and real time detectors of NO in aqueous solution. They do not require reacting NO with labels or purging of NO with an inert gas. We show that the NO electrode and MIMS are comparable in sensitivity detecting NO concentrations to 0.5,nM in aqueous solution, and both give identical results in a biological measurement, the reactions of deoxyhemoglobin with nitrite. [source]

    Structure-Dependent Electrochemical Behavior of Thienylplatinum(II) Complexes of N,N-Heterocycles

    Feng Zhao
    Abstract trans -[Pt(MeCN)(PPh3)2(2-thienyl)]BF4 (1) serves as a convenient precursor to bifunctional mononuclear trans -[Pt(PPh3)2(,1 - N - N)(2-thienyl)]BF4 [N - N = pyrazine (2); 2-chloropyrazine, (3)] and dinuclear trans,trans -[Pt2(PPh3)4(,- N - N)(2-thienyl)2](BF4)2 [(N - N = 4,4, -bipyridine (4); 4,4, -vinylenedipyridine (5)] complexes. The nuclear selectivity is conveniently controlled by the choice of the heterocyclic ligands or spacers. Both structural types 3 and 5 were confirmed by single-crystal X-ray crystallographic analyses. Their solution identities were established by positive-ion Electrospray Mass Spectrometry (ESMS). The electroactivities of these complexes were studied by cyclic voltammetry (CV). Continuous CV scans of 4 and 5 revealed variations in the redox waves with the number of scans. While the initial oxidative scan exhibited only a broad, irreversible wave, further cycling showed the growth of two additional redox couples up to about the tenth cycle. The peak currents of these redox couples began to decay with prolonged potential cycling beyond the tenth cycle. These findings are consistent with the formation of electroactive oligomers/polymers, and this conclusion is supported by visible thin film formation on the electrodes. In contrast, the mononuclear complexes (2 and 3) do not show such behavior. The films formed were further studied by repetitive potential cycling and XPS. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

    Reduction of [(C5Me5)2Mo2O5] and [(C5Me5)2Mo2O4] in Methanol/Water/Trifluoroacetate Solutions Investigated by Combined On-Line Electrochemistry/Electrospray-Ionization Mass Spectrometry

    Jenny Gun
    Abstract Complexes [Cp*2Mo2O5] (Cp* = ,5 -C5Me5) and [Cp*2Mo2O4] were investigated by combined on-line electrochemical (EC) reduction and electrospray-ionization mass spectrometry (ESI-MS) techniques in a trifluoroacetic acid buffered water/methanol solution. The reduction products at the larger negative potentials are identical for both compounds. The studies reveal the existence of a wide range of previously unknown di- and trinuclear MoV, MoIV, MoIII, and mixed-valence complexes that were identified on the basis of their masses and characteristic isotope patterns. The structures of the initial compounds and the product of electroreduction with m/z = 713,729 were supported by in situ MSn experiments that allowed the elucidation of the fragmentation pathway for the collision-induced dissociation. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

    Sample Target Substrates with Reduced Spot Size for MALDI-TOF Mass Spectrometry Based on Patterned Self-Assembled Monolayers

    Nicole Herzer
    Abstract The wetting properties of structured self-assembled monolayers are used to fabricate sample target substrates for MALDI-TOF mass spectrometry. Combining the advantages of a hydrophobic-hydrophilic surface pattern and the possibility of obtaining micrometer patterns allows an increase in the sensitivity of MALDI-TOF mass spectrometry analysis and a reduction in the traceable concentration down to fmol µL,1. This easy, cheap and fast patterning process provides substrates that allow sensitive, high-resolution mass spectrometry of dilute solutions. [source]

    Determination of Lithium Contents in Silicates by Isotope Dilution ICP-MS and its Evaluation by Isotope Dilution Thermal Ionisation Mass Spectrometry

    Takuya Moriguti
    Lithium; ICP-MS avec dilution isotopique; TIMS; matériaux silicatés de référence; météorites A precise and simple method for the determination of lithium concentrations in small amounts of silicate sample was developed by applying isotope dilution-inductively coupled plasma-mass spectrometry (ID-ICP-MS). Samples plus a Li spike were digested with HF-HClO4, dried and diluted with HNO3, and measured by ICP-MS. No matrix effects were observed for 7Li/6Li in rock solutions with a dilution factor (DF) of 97 at an ICP power of 1.7 kW. By this method, the determination of 0.5 ,g g -1 Li in a silicate sample of 1 mg can be made with a blank correction of < 1%. Lithium contents of ultrabasic to acidic silicate reference materials (JP-1, JB-2, JB-3, JA-1, JA-2, JA-3, JR-1 and JR-2 from the Geological Survey of Japan, and PCC-1 from the US Geological Survey) and chondrites (three different Allende and one Murchison sample) of 8 to 81 mg were determined. The relative standard deviation (RSD) was typically < 1.7%. Lithium contents of these samples were further determined by isotope dilution-thermal ionisation mass spectrometry (ID-TIMS). The relative differences between ID-ICP-MS and ID-TIMS were typically < 2%, indicating the high accuracy of ID-ICP-MS developed in this study. Nous avons développé une méthode simple et précise de détermination des concentrations en lithium dans de très petits échantillons silicatés. Elle est basée sur la méthode de dilution isotopique couplée à l'analyse par spectrométrie de masse avec couplage induit (ID-ICP-MS). Les échantillons auxquels est ajouté le spike de Li, sont mis en solution avec un mélange HF-HclO4, évaporés à sec, puis repris avec HNO3 et analysés à l'ICP-MS. Aucun effet de matrice n'est observé sur les rapports 7Li/6Li dans les solutions quand les facteurs de dilution sont 97 et qu'elles sont analysées avec une puissance du plasma de 1.7 kW. Par cette méthode, la détermination de 0.5 ,g g -1 de Li dans un échantillon silicaté de 1 mg peut être effectuée avec une correction de blanc < 1 %. Les teneurs en lithium des matériaux de référence de composition ultrabasique à acide (JP-1, JB-2, JB-3, JA-1, JA-2, JA-3, JR- 1 et JR-2 du Service Géologique du Japon, et PCC-1 du Service Géologique des USA) et de chondrites (trois échantillons différents d'Allende et un de Murchison), de poids variant entre 8 et 81 mg ont été déterminées. La déviation standard relative typique était < 1.7%. Les teneurs en lithium de ces échantillons ont été ensuite mesurées par dilution isotopique et spectrométrie de masse à thermo-ionisation (ID-TIMS). Les différences entre les résultats obtenus par ID-ICP-MS et ID-TIMS étaient < 2%, démontrant ainsi la grande justesse de la technique ID-ICP-MS développée dans cette étude. [source]

    Molybdenum Concentrations Measured in Eleven USGS Geochemical Reference Materials by Isotope Dilution Thermal Ionisation Mass Spectrometry

    Michael E. Wieser
    molybdène; dilution isotopique; spectrométrie de masse à; thermo-ionisation; matériaux de référence USGS Molybdenum concentrations in eleven USGS geochemical reference materials AGV-1, BCR-1, BHVO-1, BIR-1, DNC-1, DTS-1, G-2, GSP-1, MAG-1, PCC-1 and W-2 were measured by isotope dilution thermal ionisation mass spectrometry (ID-TIMS). In every case but one, the concentrations determined in this study were significantly lower than the current consensus values. Molybdenum concentrations determined by ID-TIMS are inherently more accurate and precisions may be up to an order of magnitude higher than those measured by other analytical techniques. Les concentrations en molybdène de onze matériaux géochimiques de référence de l'USGS, AGV-1, BCR-1, BHVO-1, BIR-1, DNC-1, DTS-1, G-2, GSP-1, MAG-1, PCC-1 et W-2, ont été mesurées par dilution isotopique et spectrométrie de masse à thermo-ionisation (ID-TIMS). Dans tous les cas sauf un, les concentrations déterminées dans cette étude sont nettement inférieures aux valeurs généralement admises. Les concentrations en molybdène déterminées par ID-TIMS sont par définition plus exactes et leur précision analytique peut tre améliorée d'un ordre de grandeur par rapport à celle déterminée par d'autres techniques analytiques. [source]

    Classification of cancer types by measuring variants of host response proteins using SELDI serum assays

    Eric T. Fung
    Abstract Protein expression profiling has been increasingly used to discover and characterize biomarkers that can be used for diagnostic, prognostic or therapeutic purposes. Most proteomic studies published to date have identified relatively abundant host response proteins as candidate biomarkers, which are often dismissed because of an apparent lack of specificity. We demonstrate that 2 host response proteins previously identified as candidate markers for early stage ovarian cancer, transthyretin and inter-alpha trypsin inhibitor heavy chain 4 (ITIH4), are posttranslationally modified. These modifications include proteolytic truncation, cysteinylation and glutathionylation. Assays using Surface Enhanced Laser Desorption/Ionization Time of Flight Mass Spectrometry (SELDI-TOF-MS) may provide a means to confer specificity to these proteins because of their ability to detect and quantitate multiple posttranslationally modified forms of these proteins in a single assay. Quantitative measurements of these modifications using chromatographic and antibody-based ProteinChip® array assays reveal that these posttranslational modifications occur to different extents in different cancers and that multivariate analysis permits the derivation of algorithms to improve the classification of these cancers. We have termed this process host response protein amplification cascade (HRPAC), since the process of synthesis, posttranslational modification and metabolism of host response proteins amplifies the signal of potentially low-abundant biologically active disease markers such as enzymes. © 2005 Wiley-Liss, Inc. [source]

    Identification of Modified Proteins by Mass Spectrometry

    IUBMB LIFE, Issue 2 2002
    Albert Sickmann
    Abstract Because it is obvious that high-throughput genomics do not lead to a molecular description or even a prediction of protein function, modern techniques for protein analysis become increasingly more important. Sequence analysis of proteins and peptides is not limited to the elucidation of the primary structure of a protein. The analysis of posttranslational modifications is an important task of protein chemistry in proteome research. Increased sensitivity in mass spectrometry as a result of more efficient ionization techniques and better detection systems has allowed the stepwise reduction of protein quantity for analysis. Protein spots of 2D-PAGE separated samples are now sufficient for an unequivocal identification of a protein by mass spectrometry. In addition to protein identification, a closer look at posttranslational modifications is now also possible. It is assumed that modifications such as phosphorylation or glycosylation exist on every second protein and that they are important for the protein function. [source]


    The aim of this study was to assess the proteolytic activity of Lactobacillus sakei (DSM 6333), L. plantarum (B21), and to a lesser extent, L. farciminis (DSM 20184) on meat sarcoplasmic proteins. The protein composition was assayed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and capillary electrophoresis after incubation of meat extract inoculated with bacteria. All strains showed proteolytic activity: a band about 94 kDa disappeared in samples inoculated with L. farciminis and L. plantarum and strongly decreased in those inoculated with L. sakei. The intensity of the bands with a molecular weight between 94 and 38 kDa decreased in all samples. Capillary electrophoresis analysis ascertained the disappearance of the fractions corresponding to 8.64 and 8.66 min retention time in all samples. The bands corresponding to 94 kDa and 38 kDa were, respectively, identified as glycogen phosphorylase muscle isoform and glyceraldehyde 3-phosphate dehydrogenase, by in situ digestion of protein gel bands and peptide map analysis using Matrix Assisted Laser Desorption/Ionization - Time of Flight Mass Spectrometry (MALDI-TOF MS). [source]

    Analysis of Volatile Compounds in Beef Fat by Dynamic-Headspace Solid-Phase Microextraction Combined with Gas Chromatography,Mass Spectrometry

    A. Watanabe
    ABSTRACT:, A solid-phase microextraction (SPME) technique has been applied to the determination of the volatile compounds, including diterpenoids and lactones, in cooked beef fat. The ability of static-headspace SPME to extract lactones was disappointing, regardless of the type of SPME fiber or the temperature used. Dynamic-headspace SPME extraction with 50-/30-,m divinylbenzene-Carboxen on a polydimethylsiloxane fiber at 100 °C, by contrast, enabled the analysis of volatiles, including delta-lactones, gamma-lactones, and diterpenoids, with 50-/30-,m divinylbenzene-Carboxen on a polydimethylsiloxane fiber at 100 °C. Fifty-three compounds were identified from only 0.20 g of rendered beef fat, and 76% of these showed reliable peak size repeatability: the coefficient of variation was less than 10% on the total ion chromatograms obtained from gas chromatography,mass spectrometry (GC,MS) analysis. Some lactones showed higher CV values (>10%), but single-ion mode GC,MS analysis reduced them to 10% or less. In a study of beef samples available to the Japanese market, our analytical procedure revealed significantly higher levels of 1-hexanol, octadecane, ethyl tetradecanoate, gamma-nonalactone, but lower levels of delta-decalactone, delta-dodecalactone, and neophytadiene, in Japanese Black cattle than in beef imported from Australia. [source]

    Age Determination of Ballpoint Pen Ink by Thermal Desorption and Gas Chromatography,Mass Spectrometry,

    Jürgen H. Bügler Ph.D.
    Abstract:, Two main approaches can be used for determining the age of an ink: indirect dating and direct dating. Indirect dating is based on the chemical analysis of an ink followed by comparison with known samples in a reference collection. The collection should contain information about the inks including the market introduction dates. This approach may allow for an anachronism to be detected. The second concept is based on measuring ink components that change with age. The analysis of solvents in ballpoint inks may be a useful parameter for determining the age of ink on paper. In a previous study, the authors demonstrated that thermal desorption of ink directly from paper, followed by chemical analysis using gas chromatography,mass spectrometry (GC,MS), is a promising procedure for characterizing ink-binder resins and solvents. Preliminary tests showed that monitoring the evaporation of ink solvent from ink on paper is not a suitable method for ink dating. Thermal analysis of ink on paper in two steps revealed that fresh ink releases a relative amount of solvent at a certain low temperature in a defined period of time, which decreases as the ink ages. As a consequence, this relative amount of solvent released at a certain low temperature, and its decrease with time, can be used to estimate ink age. This age-dependent parameter was studied in 85 different inks ranging in age from 1 week to 1.5 years. It was found that some inks showed a significant decrease of this parameter up to an age of several months, and that the aging process can be monitored within this period. For other inks, however, the age-dependent parameter decreases relatively fast, e.g., within a few days, to a constant level, which can be too fast for casework. Based on these results, a general procedure for assessing the age of ballpoint pen inks on paper was developed. [source]

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

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

    Identification of Organic Pigments in Automotive Coatings Using Laser Desorption Mass Spectrometry,

    Sylwia Stachura
    ABSTRACT: When one looks at an automotive coating, one sees color due to pigments. Modern organic pigments, with high molar absorptivities, may be only minor components of the mixture. Laser desorption mass spectrometry (LDMS) has been shown to be a useful tool for the analysis of colorants such as pen ink dyes. Here, LDMS is used to determine its utility for the identification of pigments, in simple media and in more complex paints. Small paint chips can be introduced into the LDMS instrument, and when an ultraviolet laser is focused on a portion of a chip, ions representative of the pigment(s) are selectively formed. Some pigments such as quinacridones and copper phthalocyanine are very stable and are desorbed and ionized intact. In contrast, benzimidazolones, which contain some single-skeletal bonds, form fragment ions. This method proves to be sensitive and convenient, as no sample preparation is required. The presence of inorganic pigments in addition to modern organic pigments can be determined, and pigments can be directly identified in actual automotive paint chip samples. [source]

    From large analogical instruments to small digital black boxes: 40 years of progress in mass spectrometry and its role in proteomics.

    Part II 198
    Abstract This is the continuation of a personal retrospective on the developments that since 1965 have given shape to Mass Spectrometry (MS) and taken it from a position of simply playing a role in Protein Chemistry to becoming an indispensable tool in Proteomics, all within a 40-year span. Part I covered the period from 1965 to 1984. This second part reviews the Mass Spectrometry timeline of events from 1985 to 2000, stopping at various time points where MS made significant contributions to protein chemistry or where the development of new instrumentation for MS represented a major advance for peptide and protein work. Major highlights in the field and their significance for peptide and protein characterization such as the advent and practical consequences of electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) are covered, including work done with triple quads, the development of time-of-flight (TOF) instruments and new ion traps and going on to the more recent work on the full characterization of the Proteome with ion traps, TOF instruments and new ionization and tagging techniques for protein sequencing. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    ESI+ MS/MS confirmation of canine ivermectin toxicity,

    A. F. Lehner
    Abstract Ivermectin is a semisynthetic macrocyclic lactone anthelmintic of the avermectin family derived from Streptomyces fermentation products. Avermectins are used as antiparasitic agents in domestic animals; although considered relatively safe, one must consider animal species, breed, weight, and age in dosage determinations. In January 2006, two canines were presented to the UK Livestock Disease Diagnostic Center after dying from suspected ivermectin overdoses [30,50 mg/kg body weight]. To confirm this clinical diagnosis we developed a rapid, sensitive semiquantitative ElectroSpray Ionization,Mass Spectrometry (ESI/MS) method for ivermectin in canine tissue samples. Pharmaceutical ivermectin contains two ivermectins differing by a single methyl group, and each compound forms interpretation-confounding adducts with tissue Na+ and K+ ions. We now report that ivermectin administration was clearly confirmed by comparison with standard and dosage forms of ivermectin, and simple proportionalities based on mass spectral intensity of respective molecular ions allowed semiquantitative estimates of injection site tissue concentrations of 20 and 40 µg/g tissue (wet weight) in these animals, consistent with the history of ivermectin administration and the clinical signs observed. There is a distinct need for both rapid detection and confirmation of toxic exposures in veterinary diagnostics, whether for interpretation of clinical cases antemortem or for forensic reasons postmortem. It is vital that interpreters of analytical results have appropriate guidance in the scientific literature and elsewhere so as to enable clear-cut answers. The method presented here is suitable for routine diagnostic work in that it allows rapid extraction of ivermectin from tissue samples, avoids the need for high-performance liquid chromatography and allows ready interpretation of the multiple ivermectin species seen by ESI+ MS/MS in samples originating from veterinary dosage forms. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    The application of carbon isotope ratio mass spectrometry to doping control

    Adam T. Cawley
    Abstract The administration of synthetic steroid copies is one of the most important issues facing sports. Doping control laboratories accredited by the World Anti-Doping Agency (WADA) require methods of analysis that allow endogenous steroids to be distinguished from their synthetic analogs in urine. The ability to measure isotope distribution at natural abundance with high accuracy and precision has increased the application of Gas Chromatography,Combustion,Isotope Ratio Mass Spectrometry (GC,C,IRMS) to doping control in recent years. GC,C,IRMS is capable of measuring the carbon isotope ratio (,13C) of urinary steroids and confirm their synthetic origin based on the abnormal 13C content. This tutorial describes some of the complexities encountered by obtaining valid ,13C measurements from GC,C,IRMS and the need for careful interpretation of all relevant information concerning an individual's metabolism in order to make an informed decision with respect to a doping violation. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Editorial, 25th Informal Meeting on Mass Spectrometry

    Pietro Traldi

    Simultaneous separation and identification of oligomeric procyanidins and anthocyanin-derived pigments in raw red wine by HPLC-UV-ESI-MSn

    S. Pati
    Abstract Samples of raw red wine (Primitivo di Manduria, Apulia, Southern Italy) were analysed without any pre-treatment (except 1 : 2 dilution with water) using HPLC with detection based on UV absorbance and Electrospray Ionisation Sequential Mass Spectrometry (ESI-MSn, with n = 1,3) in a series configuration. In particular, absorbance at 520 nm was monitored for UV detection in order to identify pigments responsible for wine colour. On the other hand, two subsequent stages of MS detection based on positive ions were adopted. The first consisted of an explorative MS acquisition, aimed at the individuation of the m/z ratios for positively charged compounds; the second was based on fragmentation of the detected ions within an ion trap analyser, followed by MS/MS and, if required, MS3 acquisitions. The synergy between UV detection and MSn analysis led to the identification of 41 pigments, which can be classified into five groups: grape anthocyanins, pyranoanthocyanins, vinyl-linked anthocyanin-flavanol pigments, ethyl-bridged anthocyanin-flavanol pigments and flavanol-anthocyanin compounds. Many isomeric and oligomeric structures were found within each group. A further class of compounds, not absorbing in the visible spectrum, could be also characterised by ESI-MSn and corresponded to B-type procyanidins, i.e. proanthocyanidins arising from C4,C8/C4,C6 couplings between catechin or epicatechin units. In particular, oligomeric structures (from dimers to pentamers), often present with several isomers, were identified and their fragmentation patterns clarified. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    Measurement of pulmonary surfactant disaturated-phosphatidylcholine synthesis in human infants using deuterium incorporation from body water

    Paola E. Cogo
    Abstract The aim of the study was to determine surfactant palmitate disaturated-phosphatidylcholine (DSPC-PA) synthesis in vivo in humans by the incorporation of deuterium from total body water into DSPC-PA under steady state condition. We studied three newborns and one infant (body weight (BW) 4.6 ± 2.9 kg, gestational age 37.5 ± 2 weeks, age 9 ± 9 days) and four preterm newborns (BW 1.3 ± 0.6 kg, gestational age 30.3 ± 2.5 weeks, postnatal age 8.8 ± 9.2 h). All infants were mechanically ventilated during the study and the four preterm infants received exogenous surfactant at the start of the study. We administered 0.44 g 2H2O/kg BW as a bolus intravenously, followed by 0.0125 g 2H2O/kg BW every 6 h to maintain deuterium enrichment at plateau over 2 days. Urine samples and tracheal aspirates (TA) were obtained prior to dosing and every 6 h thereafter. Isotopic enrichment curves of DSPC-PA from sequential TA and urine deuterium enrichments were analyzed by Gas Chromatography-Isotope Ratio,Mass Spectrometry (GC-IRMS) and normalized for Vienna Standard Mean Ocean Water. Enrichment data were used to measure DSPC-PA fractional synthesis rate (FSR) from the linear portion of the DSPC-PA enrichment rise over time, relative to plateau enrichment of urine deuterium. Secretion time (ST) was defined as the time lag between the start of the study and the appearance of DSPC-PA deuterium enrichment in TA. Data were given as mean ± SD. All study infants reached deuterium-steady state in urine. DSPC-PA FSR was 6.5 ± 2.8%/day (range 2.6,10.2). FSR for infants who did not receive exogenous surfactant was 5.7 ± 3.5%/day (range 2.6,9.9%/day) and 7.3 ± 2.1%/day (range 5.1,10.2%/day) in the preterms, whereas DSPC-PA ST was 10 ± 10 h and 31 ± 10 h respectively. Surfactant DSPC-PA synthesis can be measured in humans by the incorporation of deuterium from body water. This study is a simpler and less invasive method compared to previously published methods on surfactant kinetics by means of stable isotopes. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Peptide and protein characterization by high-rate electron capture dissociation Fourier transform ion cyclotron resonance mass spectrometry.


    The original article to which this Erratum refers was published in Journal of Mass Spectrometry 39 (7) 2004; 719,729. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    Current Awareness in Journal of Mass Spectrometry

    Article first published online: 22 APR 200
    In order to keep subscribers up-to-date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of mass spectrometry. Each bibliography is divided into 11 sections: 1 Books, Reviews & Symposia; 2 Instrumental Techniques & Methods; 3 Gas Phase Ion Chemistry; 4 Biology/Biochemistry: Amino Acids, Peptides & Proteins; Carbohydrates; Lipids; Nucleic Acids; 5 Pharmacology/Toxicology; 6 Natural Products; 7 Analysis of Organic Compounds; 8 Analysis of Inorganics/Organometallics; 9 Surface Analysis; 10 Environmental Analysis; 11 Elemental Analysis. Within each section, articles are listed in alphabetical order with respect to author (4 Weeks journals - Search completed at 15th. Jan. 2003) [source]

    Current Literature in Journal of Mass Spectrometry

    Article first published online: 29 JAN 200
    In order to keep subscribers up-to-date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of mass spectrometry. Each bibliography is divided into 11 sections: 1 Books, Reviews & Symposia; 2 Instrumental Techniques & Methods; 3 Gas Phase Ion Chemistry; 4 Biology/Biochemistry: Amino Acids, Peptides & Proteins; Carbohydrates; Lipids; Nucleic Acids; 5 Pharmacology/Toxicology; 6 Natural Products; 7 Analysis of Organic Compounds; 8 Analysis of Inorganics/Organometallics; 9 Surface Analysis; 10 Environmental Analysis; 11 Elemental Analysis. Within each section, articles are listed in alphabetical order with respect to author (2 Weeks journals - Search completed at 6th. Nov. 2002) [source]