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Sample records for pyrolysis-gas chromatography-mass spectrometry

  1. Identification of Synthetic Polymers and Copolymers by Analytical Pyrolysis-Gas Chromatography/Mass Spectrometry

    ERIC Educational Resources Information Center

    Kusch, Peter

    2014-01-01

    An experiment for the identification of synthetic polymers and copolymers by analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was developed and performed in the polymer analysis courses for third-year undergraduate students of chemistry with material sciences, and for first-year postgraduate students of polymer sciences. In…

  2. Identification of Synthetic Polymers and Copolymers by Analytical Pyrolysis-Gas Chromatography/Mass Spectrometry

    ERIC Educational Resources Information Center

    Kusch, Peter

    2014-01-01

    An experiment for the identification of synthetic polymers and copolymers by analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was developed and performed in the polymer analysis courses for third-year undergraduate students of chemistry with material sciences, and for first-year postgraduate students of polymer sciences. In…

  3. [Analysis of cracking gas compressor fouling by pyrolysis gas chromatography-mass spectrometry].

    PubMed

    Hu, Yunfeng; Fang, Fei; Wei, Tao; Liu, Shuqing; Jiang, Guangshen; Cai, Jun

    2013-06-01

    The fouling from the different sections of the cracked gas compressor in Daqing Petrochemical Corporation was analyzed by pyrolysis gas chromatography-mass spectrometry (Py/GC-MS). All the samples were cracked in RJ-1 tube furnace cracker at the cracking temperature of 500 degrees C, and separated with a 60 m DB-1 capillary column. An electron impact ionization (EI) source was used with the ionizing voltage of 70 eV. The results showed the formation of fouling was closely related with cyclopentadiene which accounted for about 50% of the cracking products. Other components detected were 1-butylene, propylene, methane and n-butane. This Py/GC-MS method can be used as an effective approach to analyze the causes of fouling in the petrochemical plants.

  4. Whole Microorganisms Studied by Pyrolysis-Gas Chromatography-Mass Spectrometry: Significance for Extraterrestrial Life Detection Experiments 1

    PubMed Central

    Simmonds, Peter G.

    1970-01-01

    Pyrolysis-gas chromatography-mass spectrometric studies of two microorganisms, Micrococcus luteus and Bacillus subtilis var. niger, indicate that the majority of thermal fragments originate from the principal classes of bio-organic matter found in living systems such as protein and carbohydrate. Furthermore, there is a close qualitative similarity between the type of pyrolysis products found in microorganisms and the pyrolysates of other biological materials. Conversely, there is very little correlation between microbial pyrolysates and comparable pyrolysis studies of meteoritic and fossil organic matter. These observations will aid in the interpretation of a soil organic analysis experiment to be performed on the surface of Mars in 1975. The science payload of this landed mission will include a combined pyrolysis-gas chromatography-mass spectrometry instrument as well as several “direct biology experiments” which are designed to search for extraterrestrial life. PMID:16349890

  5. Study of the microbiodegradation of terpenoid resin-based varnishes from easel painting using pyrolysis-gas chromatography-mass spectrometry and gas chromatography-mass spectrometry.

    PubMed

    Doménech-Carbó, María Teresa; Osete-Cortina, Laura; de la Cruz Cañizares, Juana; Bolívar-Galiano, Fernando; Romero-Noguera, Julio; Fernández-Vivas, María Antonia; Martín-Sánchez, Inés

    2006-08-01

    The alterations produced by microbiological attack on terpenoid resin-based varnishes from panel and canvas paintings have been evaluated using pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) and gas chromatography-mass spectrometry (GC-MS). The proposed methods include the on-line derivatisation of drying oils and diterpenoid resins using hexamethyldisilazane during pyrolysis and the application of methyl chloroformate as a derivatisation reagent for triterpenoid resins in GC-MS. Two types of specimens, consisting of model oil medium prepared from linseed oil and model spirit varnishes prepared from colophony and mastic resins dissolved in turpentine, have been used as reference materials. For a series of specimens upon which different genera of bacteria and fungi were inoculated and encouraged to grow, analyses indicated that no mechanisms that commonly occur during the attack of enzymes on drying oils and terpenoid biodegraders were observed to occur in the oil medium and varnishes studied. Thus, the degradation pathways observed in the performed trials usually occur as consequence of natural ageing. Specific trials consisting of the application of biocides to uninoculated colophony varnish resulted in the identification of processes that produce undesirable degradation of the varnish due to interactions between the biocide and the varnish components. Finally, the studied biocides--Biotin, New-Des and Nipagine--generally exhibited good inhibiting effects on the microorganisms studied, although some interesting differences were found between them regarding the application method and type of biocide.

  6. Determination of Dihydroqinghaosu in Blood by Pyrolysis Gas Chromatography/Mass Spectrometry

    DTIC Science & Technology

    1988-01-15

    capillary the therapeutic range, our laboratory sought to develop new column gas chromatography/mass spectrometry ( GCMS ) specific and sensitive methodologies...paper, the results on the development and validation of packed for pharmacoklneUc an metabolism studies In animals. and capillary column gas...respectively. Petroleum ether washave been treated with QHS or its derivatives in China with purchased from Mallinckrodt, Inc. (Paris, KY), and ethyl acetate

  7. Pyrolysis-gas chromatography/mass spectrometry analyses of biological particulates collected during recent space shuttle missions

    NASA Technical Reports Server (NTRS)

    Matney, M. L.; Limero, T. F.; James, J. T.

    1994-01-01

    Biological particulates collected on air filters during shuttle missions (STS-40 and STS-42) were identified using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). A method was developed for identifying the atmospheric particles and their sources through the analysis of standard materials and the selection of "marker" compounds specific to the particle type. Pyrolysis spectra of biological standards were compared with those of airborne particles collected during two space shuttle missions; marker compounds present in the shuttle particle spectra were matched with those of the standards to identify the source of particles. Particles of 0,5--1-mm diameter and weighing as little as 40 micrograms could be identified using this technique. The Py-GC/MS method identified rat food and soilless plant-growth media as two sources of particles collected from the shuttle atmosphere during flight.

  8. Comparative study on pyrolysis of lignocellulosic and algal biomass using pyrolysis-gas chromatography/mass spectrometry.

    PubMed

    Li, Kai; Zhang, Liqiang; Zhu, Liang; Zhu, Xifeng

    2017-06-01

    The cornstalk and chlorella were selected as the representative of lignocelulosic and algal biomass, and the pyrolysis experiments of them were carried out using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The physicochemical properties of samples and the pyrolytic product distribution were presented. And then the compositional differences between the two kinds of pyrolytic products were studied, the relevant pyrolysis mechanisms were analyzed systematically. Pyrolytic vapor from lignocellulosic biomass contained more phenolic and carbonyl compounds while that from algal biomass contained more long-chain fatty acids, nitrogen-containing compounds and fewer carbonyl compounds. Maillard reaction is conducive to the conversion of carbonyl compounds to nitrogenous heterocyclic compounds with better thermal stability. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. The analysis of tire rubber traces collected after braking incidents using Pyrolysis-GasChromatography/Mass Spectrometry.

    PubMed

    Sarkissian, Garry

    2007-09-01

    Automobile tire marks can routinely be found at the scenes of crime, particularly hit-and-run accidents and are left on road surfaces because of sudden braking or the wheels spinning. The tire marks are left due to the friction between the tire rubber and the solid road surface, and do not always demonstrate the tire tread pattern. However, the tire mark will contain traces of the tire. In this study, Pyrolysis Gas Chromatography/Mass Spectrometry was used to analyze 12 tires from different manufacturer's and their traces collected after braking incidents. Tire marks were left on a conglomerate road surface with sudden braking. The samples were pyrolysed without removal of contaminant in a micro-furnace type pyrolyser. Quantitative and qualitative analysis were performed on all the samples. All 12 samples were distinguished from each other. Each of the tire traces were identified as coming from there original source.

  10. The identification of synthetic organic pigments in modern paints and modern paintings using pyrolysis-gas chromatography-mass spectrometry.

    PubMed

    Russell, Joanna; Singer, Brian W; Perry, Justin J; Bacon, Anne

    2011-05-01

    A collection of more than 70 synthetic organic pigments were analysed using pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). We report on the analysis of diketo-pyrrolo-pyrrole, isoindolinone and perylene pigments which are classes not previously reported as being analysed by this technique. We also report on a number of azo pigments (2-naphthol, naphthol AS, arylide, diarylide, benzimidazolone and disazo condensation pigments) and phthalocyanine pigments, the Py-GC-MS analysis of which has not been previously reported. The members of each class were found to fragment in a consistent way and the pyrolysis products are reported. The technique was successfully applied to the analysis of paints used by the artist Francis Bacon (1909-1992), to simultaneously identify synthetic organic pigments and synthetic binding media in two samples of paint taken from Bacon's studio and micro-samples taken from three of his paintings and one painting attributed to him.

  11. The characterization of eight maceral concentrates by means of Curie point pyrolysis-gas chromatography and Curie point pyrolysis-gas chromatography-mass spectrometry

    NASA Astrophysics Data System (ADS)

    Nip, Margriet; De Leeuw, J. W.; Schenck, P. A.

    1988-03-01

    In order to study the relationships between the chemical structures of coals, coal macerals and their precursors (plant tissues), eight coal macerals originating from the Yorkshire coal basin (U.K.) were studied by Curie point pyrolysis-gas chromatography and Curie point pyrolysis-gas chromatography-mass spectrometry. The samples were selected on the basis of a previous study of a large set of macerals. The macerals were studied in order to relate structural moieties of the macerals, as reflected by their pyrolysis products, to structural elements of their likely precursors, plant tissues. The maceral pyrolysates mainly consist of alkylbenzenes, alkylnaphthalenes, alkylphenols and series of straight-chain alk-l-enes and alkanes over a wide molecular weight range. The relative contribution of the (hydroxy)aromatic pyrolysis products and of the straight-chain alk-l-enes and alkanes to each maceral pyrolysate was calculated, although the internal distribution patterns of the alkyl derivatives of these pyrolysis products exhibited to a certain extent dissimilarities. Differences between the relative contributions of these pyrolysis products to the pyrolysates of different macerals with the same coal rank and to those of similar macerals with different coal rank depend on differences in precursor material and the chemical modification of these precursors upon increasing coalification. Multivariate data treatment by means of factor analysis was chosen to compare the pyrolysis data - represented by these histograms - with the petrographic data and the proximate and ultimate analysis values of the macerals. In addition, similar analyses was performed on the macerals using such a low Curie temperature (358°C), that from some of the macerals "thermal extracts" were obtained, containing a series of n-alkanes and some isoprenoids such as pristane and phytane. Although these thermal extracts represent only a low percentage by weight of the maceral samples, their existence

  12. Pyrolysis-gas chromatography-mass spectrometry of a series of bile acid sequestrants.

    PubMed

    Haskins, N J; Eckers, C; Mitchell, R

    1992-09-01

    Pyrolysis of a series of polymers based on polystyrene and used as bile acid sequestrants produced characteristic mixtures of compounds which were analysed by gas chromatography-mass spectrometry. The nature of the substituent groups was clearly apparent while the polymer backbone gave rise to representative styrenes. The reproducibility of the results was examined by experimenting with the temperature of pyrolysis. It was found that at low temperatures very little fragmentation of the polystyrene backbone occurred but the substituents were still released in high yield. The orientation of the various substituted styrenes generated by pyrolysis was confirmed by the use of gas chromatography with infrared and mass spectrometric detection.

  13. Hydrocarbon phenotyping of algal species using pyrolysis-gas chromatography mass spectrometry

    PubMed Central

    2010-01-01

    Background Biofuels derived from algae biomass and algae lipids might reduce dependence on fossil fuels. Existing analytical techniques need to facilitate rapid characterization of algal species by phenotyping hydrocarbon-related constituents. Results In this study, we compared the hydrocarbon rich algae Botryococcus braunii against the photoautotrophic model algae Chlamydomonas reinhardtii using pyrolysis-gas chromatography quadrupole mass spectrometry (pyGC-MS). Sequences of up to 48 dried samples can be analyzed using pyGC-MS in an automated manner without any sample preparation. Chromatograms of 30-min run times are sufficient to profile pyrolysis products from C8 to C40 carbon chain length. The freely available software tools AMDIS and SpectConnect enables straightforward data processing. In Botryococcus samples, we identified fatty acids, vitamins, sterols and fatty acid esters and several long chain hydrocarbons. The algae species C. reinhardtii, B. braunii race A and B. braunii race B were readily discriminated using their hydrocarbon phenotypes. Substructure annotation and spectral clustering yielded network graphs of similar components for visual overviews of abundant and minor constituents. Conclusion Pyrolysis-GC-MS facilitates large scale screening of hydrocarbon phenotypes for comparisons of strain differences in algae or impact of altered growth and nutrient conditions. PMID:20492649

  14. Characterization of commercial synthetic resins by pyrolysis-gas chromatography/mass spectrometry: application to modern art and conservation.

    PubMed

    Peris-Vicente, J; Baumer, U; Stege, H; Lutzenberger, K; Gimeno Adelantado, J V

    2009-04-15

    To characterize a set of synthetic resins, a methodology by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) has been developed. The studied reference materials were commercial versions of a wide range of synthetic resins. For each polymer, the pyrolytic and chromatographic conditions were optimized to adequately resolve the fragment mixture in a short time. The proposed analytical method does not require previous treatment of the sample, and due to its high sensitivity, only a small sample quantity in the microgram range can be used. The pyrolysis temperature was found to have little effect on the obtained pyrograms. The summarized data set for the individual polymer materials, especially the characteristic fragments with a structure close to the monomeric unit, was useful to identify commercial synthetic resins. These materials were used in the art and conservation field, as binding media, paint additives, painting varnishes, coatings, or consolidants. Two case studies are introduced where direct Py-GC/MS and thermally assisted hydrolysis and methylation GC/MS were applied on art objects: first, a modern gluing material of a medieval reverse glass painting, and the second example, the binding medium of a painting by Georg Baselitz ("Senta", 1992/1993) from the Sammlung Moderne Kunst at the Pinakothek der Moderne, Munich.

  15. Characterization of synthetic polymers and speck impurities in cellulose pulp: a comparison between pyrolysis-gas chromatography-mass spectrometry and Fourier transform infrared spectroscopy.

    PubMed

    Silvério, F O; Barbosa, L C A; Maltha, C R A; Piló-Veloso, D

    2009-06-08

    Pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) and Fourier transform infrared (FT-IR) spectroscopy were used for characterizing specks in cellulose pulp, polymeric materials and pitch formed during the cellulose extraction and paper production in the Brazilian mill. Three samples were analyzed and the pyrograms and infrared spectra obtained were compared. The results showed that the analytical pyrolysis more effectively differentiated between impurities (dirt specks) when compared to the infrared spectroscopy.

  16. Sorption-desorption behavior of phenanthrene elucidated by pyrolysis-gas chromatography-mass spectrometry studies of soil organic matter

    SciTech Connect

    Schultz, L.F.; Young, T.M.; Higashi, R.M.

    1999-08-01

    Commonly used partitioning models of hydrophobic organic contaminant sorption in soil, which treat all soil organic matter (SOM) as having identical structure, are unable to explain differences in organic carbon-normalized sorption coefficients (K{sub OC}) among sorbents, isotherm nonlinearity, and sorption-desorption hysteresis. This study relates one index of SOM composition, structural fragments quantified by pyrolysis-gas chromatography-mass spectrometry, to aqueous and supercritical carbon dioxide (SC CO{sub 2}) sorption-desorption parameters. Results show positive correlations between aqueous K{sub OC}s and hydrocarbon fragment peak areas and negative correlation to N- and O-containing peaks, which is consistent with hypotheses attributing sorption of phenanthrene to hydrophobic sorbent domains. Positive correlation between Freundlich n values in SC CO{sub 2} and hydrocarbon fragments with negative correlation to N- and O-containing fragments suggests that energetic heterogeneity of polar environments controls nonlinearity in this solvent of limited polarity. Aqueous sorption-desorption hysteresis appears to be suppressed by N- and O-containing moieties and correlates with decreased thermal desorption of phenanthrene at 800 C. The SC CO{sub 2} extraction efficiency and, to a lesser degree, the desorption response when methanol is added as a cosolvent indicate that polar functional groups play a role in retarding phenanthrene desorption during SC CO{sub 2} extraction. Organic matter pyrolysis under varying time and temperature conditions indicates that pyrolysis fragments that do not significantly correlated with functional trends likely evolve by a different pyrolytic mechanism and are generally poorly correlated with sorption-desorption properties. The level of structural detail utilized in structure-function correlations in this work exceeds previous efforts to relate sorption behavior to sorbent structure. However, the work reveals that certain sorption

  17. Using Ramped Pyrolysis - Gas Chromatography - Mass Spectrometry to Evaluate Petroleum Hydrocarbons Following the Deepwater Horizon Oil Spill

    NASA Astrophysics Data System (ADS)

    Evans, M.; Rosenheim, B. E.; Bacosa, H. P.; Liu, J.; Liu, Z.

    2016-02-01

    In summer of 2010, the Deepwater Horizon oil spill polluted hundreds of miles of coastline along the Gulf of Mexico. A combination of human-mediated and natural weathering processes then altered the chemical composition (i.e. toxicity) of this spilled crude oil over time and space. One of the most important, yet challenging, aspects of oil spill science is to quantify these chemical changes in natural environments. In this study, we develop ramped pyrolysis - gas chromatography - mass spectrometry (Py-GC-MS) to address this challenge. In this technique, 0.1mg of freeze-dried sample is pyrolyzed over a gradual temperature ramp (50-650°C). The eluded gas is cold-trapped over different thermal ranges (a.k.a. thermal slicing) and each range is individually analyzed via GC-MS, yielding quantifiable, compound-specific results. Py-GC-MS with thermal slicing has never been used for petroleum hydrocarbon analysis, but it has many advantages - it uses minimal sample, is time efficient and does not require sample preparation (minimizing compound loss and increasing the analytical window). During development of this method, we analyzed oiled sediments and tar collected on Grand Isle, Louisiana from 2010-2012. We quantified n-alkane (C10-C38), polycyclic aromatic hydrocarbon (PAH) and hopane content and confirmed these results with traditional solvent extraction, silica gel fractionation and mass spectrometry. Overall, we found rapid depletion of n-alkanes and PAHs (>90% depletion) in all samples within one year of Deepwater Horizon. After this, n-alkanes were almost 100% depleted by 2012, while PAH degradation continued to a maximum total degradation of 99% and 98% in sediment and tar, respectively. This not only describes the fate of petroleum compounds in salt marshes and beach deposits over time, but also complements previous radiocarbon studies of the same samples showing different rates of degradation in different micro-environments. In addition, the results presented

  18. Titan's organic aerosols: Molecular composition and structure of laboratory analogues inferred from pyrolysis gas chromatography mass spectrometry analysis

    NASA Astrophysics Data System (ADS)

    Morisson, Marietta; Szopa, Cyril; Carrasco, Nathalie; Buch, Arnaud; Gautier, Thomas

    2016-10-01

    Analogues of Titan's aerosols are of primary interest in the understanding of Titan's atmospheric chemistry and climate, and in the development of in situ instrumentation for future space missions. Numerous studies have been carried out to characterize laboratory analogues of Titan aerosols (tholins), but their molecular composition and structure are still poorly known. If pyrolysis gas chromatography mass spectrometry (pyr-GCMS) has been used for years to give clues about their chemical composition, highly disparate results were obtained with this technique. They can be attributed to the variety of analytical conditions used for pyr-GCMS analyses, and/or to differences in the nature of the analogues analyzed, that were produced with different laboratory set-ups under various operating conditions. In order to have a better description of Titan's tholin's molecular composition by pyr-GCMS, we carried out a systematic study with two major objectives: (i) exploring the pyr-GCMS analytical parameters to find the optimal ones for the detection of a wide range of chemical products allowing a characterization of the tholins composition as comprehensive as possible, and (ii) highlighting the role of the CH4 ratio in the gaseous reactive medium on the tholin's molecular structure. We used a radio-frequency plasma discharge to synthetize tholins with different concentrations of CH4 diluted in N2. The samples were pyrolyzed at temperatures covering the 200-700°C range. The extracted gases were then analyzed by GCMS for their molecular identification. The optimal pyrolysis temperature for characterizing the molecular composition of our tholins by GCMS analysis is found to be 600°C. This temperature choice results from the best compromise between the number of compounds released, the quality of the signal and the appearance of pyrolysis artifacts. About a hundred molecules are identified as pyrolysates. A common major chromatographic pattern appears clearly for all the

  19. Analysis of Mixed Aryl/Alkyl Esters by Pyrolysis Gas Chromatography-Mass Spectrometry in the Presence of Perchlorate

    NASA Technical Reports Server (NTRS)

    Burton, A. S.; Locke, D. R.; Lewis, E. K.

    2017-01-01

    Mars is an important target for Astrobiology. A key goal of the MSL mission was to determine whether Mars was habitable in the past, a que-tion that has now been definitely determined to be yes. Another key goal for Mars exploration is to understand the origin and distribution of organic material on Mars; this question is being addressed by the SAM instrument on MSL, and will also be informed by two upcoming Mars exploration missions, ExoMars and Mars 2020. These latter two missions have instrumentation capable of detecting and characterize organic molecules. Over the next decade, these missions will analyze organics in surface, near-surface and sub-surface samples. Each mission has the capability to analyze organics by different methods (pyrolysis gas chromatography-mass spectrometry [py-GC-MS]; laser desorption and thermal volatilization GC-MS; and Raman spectroscopy). Plausibly extraterrestrial organics were recently discovered by the Mars Science Laboratory (MSL), providing an important first step towards understanding the organic inventory on Mars [1]. The compounds detected were chlorobenzenes and chloroalkanes, but it was argued that chlorination of these compounds occurred during pyrolysis of samples containing unchlorinated organics in the presence of perchlorate. A recent report analyzed a suite of aromatic (benzene, toluene, benzoic acid, phthalic acid, and mellitic acid) and aliphatic (acetic acid, propane, propanol, and hexane) by pyrolysis under SAM-like conditions in the presence of perchlorate to attempt to constrain possible precursor molecules for the organic molecules detected on Mars. For aromatic compounds, the aromatic acids all readily produced SAM-relevant chlorobenzes, whereas benzene and toluene did not. This observation suggests that the chlorobenzene detected on Mars could have derived from compounds like mellitic acid, consistent with the previous hypothesis by Benner et al. [3]. Among the aliphatic molecules, it was shown that

  20. Titan's Organic Aerosols : Molecular Composition And Structure Inferred From Systematic Pyrolysis Gas Chromatography Mass Spectrometry Analysis of Analogues

    NASA Astrophysics Data System (ADS)

    Morisson, Marietta; Szopa, Cyril; Buch, Arnaud; Carrasco, Nathalie; Gautier, Thomas

    2015-04-01

    In spite of numerous studies carried out to characterize the chemical composition of laboratory analogues of Titan aerosols (tholins), their molecular composition as well as their structuration are still little known. If Pyrolysis gas chromatography mass spectrometry (Pyr-GCMS) has been used for years to give clues about this composition, the highly disparate results obtained show that they can be attributed to the analytical conditions used, to differences in the nature of the analogues studied, or both. In order to have a better description of Titan's tholins molecular composition, we led a systematic analysis of these materials by pyr-GCMS, exploring the analytical parameters to estimate the biases this technique can induce. With this aim, we used the PAMPRE experiment, a capacitively coupled RF cold plasma reactor (Szopa et al. 2006), to synthetize tholins with 2%, 5% and 10% of CH4 in N2. The three samples were systematically pyrolyzed in the temperature range 200-600°C with a 100°C step. The evolved gases were then injected into a GC-MS device for molecular identification. This systematic pyr-GC-MS analysis had two major objectives: (i) optimizing all the analytical parameters for the detection of a wide range of compounds and thus a characterization of the tholins composition as comprehensive as possible, and (ii) highlighting the role of the CH4 ratio on the tholins molecular structure. About a hundred of molecules have been identified in the pyrolysis products. Although an identical major pattern of nitriles and ethylene appears clearly for the three samples, some discriminant signatures were highlighted. The samples mainly differ by the number of released compounds. The results show especially an increase in the hydrocarbonaceous chains when the CH4 ratio increases. At the opposite, the formation of poly-nitrogenous compounds seems to be easier for lower CH4 ratios. We also performed a semi-quantitative study on the best represented chemical family in

  1. Characterisation of beeswax in works of art by gas chromatography-mass spectrometry and pyrolysis-gas chromatography-mass spectrometry procedures.

    PubMed

    Bonaduce, Ilaria; Colombini, Maria Perla

    2004-03-05

    Pyrolysis (Py) with in situ derivatisation with hexamethyldisilazane-gas chroma-break tography-mass spectrometry (GC-MS) and a gas chromatography-mass spectrometry procedure based on microwave-assisted saponification were used to identify the organic components in small sized beeswax samples. With the latter procedure quantitative recoveries can be made and hydrocarbons, alcohols and omega-1-diols in the neutral fraction, and fatty acids and omega-1-hydroxy acids in the acidic fraction can be efficiently separated and detected. Both procedures were used to characterise a wax anatomic sculpture "The Plague" (1691-1694) by Gaetano Zumbo, resulting in the identification of beeswax and a Pinaceae resin. The GC-MS analysis brought to light some essential differences in beeswax composition between the raw material and the old modelled wax thus giving some clear indications about the recipe used by the sculptor.

  2. Recognition of chitin and proteins in invertebrate cuticles using analytical pyrolysis/gas chromatography and pyrolysis/gas chromatography/mass spectrometry.

    PubMed

    Stankiewicz, B A; Van Bergen, P F; Duncan, I J; Carter, J F; Briggs, D E; Evershed, R P

    1996-01-01

    Flash pyrolysis/gas chromatography (py/GC) and py/GC/mass spectrometry (MS) have been utilized to characterize the cuticles of invertebrates chemically. Pyrolysis products have been identified and assigned to specific cuticular components. Acetylpyridones, acetamidofuran, 3-acetamido-5-methylfuran and 3-acetamido-(2 and 4)-pyrones are proposed as characteristic pyrolysis markers for chitin. Pyrolysis products displaying ions of m/z 70, 154, 168, 194 are thought to derive from diketopiperazine structures and provide potential markers for proteins and peptides in which proline, alanine, valine, arginine and glycine are the dominant amino acids. These products, constituting specific pyrolysis markers for invertebrate cuticles, may reflect the amino acid composition of their constituent structural proteins. The source of the various pyrolysis products of proteins has been verified by pyrolysis of reference proteins, peptides and amino acid mixtures. The presence of additional pyrolysis products related directly to histidine and catechol moieties is consistent with the chemical structure and composition proposed for arthropod cuticles based on recent work utilizing solid state 13C and 15N nuclear magnetic resonance. This study constitutes the first comprehensive chemical characterization of the pyrolysis products of invertebrate cuticles and provides the basis for future investigations requiring qualitative screening for cross-linked chitin and proteins in modern and fossil cuticles and in materials, e.g. geopolymers, that may be derived from them.

  3. Gas chromatography/mass spectrometry and pyrolysis-gas chromatography/mass spectrometry for the chemical characterisation of modern and archaeological figs (Ficus carica).

    PubMed

    Ribechini, Erika; Pérez-Arantegui, Josefina; Colombini, Maria Perla

    2011-06-24

    Gas chromatography/mass spectrometry (GC/MS) after alkaline hydrolysis, solvent extraction and trimethylsilylation, and analytical pyrolysis using hexamethyldisilazane (HMDS) for in situ derivatisation followed by gas chromatographic/mass spectrometric analysis (Pyrolysis-silylation-GC/MS) were used to investigate the hydrolysable and soluble constituents, and the polymerised macromolecules of an archaeological fig (Ficus carica) recovered in Zaragoza (Spain), as well as of modern figs. The main aim was to study the compositional alterations undergone by the fig tissues in a particular archaeological environment: the fig was in a vessel and covered by a layer of a mixture of orpiment and gypsum. A comparison between the GC/MS results from modern and archaeological figs revealed that degradative reactions took place, leading to the disappearance/depletion of reactive (unsaturated fatty acids) and sensitive compounds (phytosterols and triterpenes). Py-silylation-GC/MS data provided evidence of a significant degradation of the saccharide and lipid components of the fig tissue, which left a residue enriched in polyphenols and polyesters. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Pyrolysis-gas chromatography/mass spectrometry of a coal extract and its fractions separated by planar chromatography: correlation of structural features with molecular mass

    PubMed

    Islas; Suelves; Carter; Herod; Kandiyoti

    2000-01-01

    The structural characterisation of a coal liquefaction extract and its three fractions separated by planar chromatography has been described. Size exclusion chromatography showed the molecular mass distributions to become progressively larger with decreasing mobility on the plate. UV-fluorescence spectroscopy of the fractions indicated parallel increases in the sizes of polynuclear aromatic ring systems. Analysis by probe-mass spectrometry of the 'whole' coal extract showed the expected array of small polynuclear aromatic groups extending to m/z 450. The probe mass spectra of the lightest fraction ('mobile in pyridine and acetonitrile') showed similar features, except for effects due to vacuum drying to remove solvent. In sharp contrast, the two heaviest fractions ('mobile in pyridine and immobile in acetonitrile' and 'immobile in pyridine') showed no significant ions other than those from residual NMP solvent (m/z 98 and 99). Pyrolysis-gas chromatography/mass spectrometry of these two heaviest fractions showed only traces of aromatic compounds or fragments. The aromatic pyrolysis products of these fractions were too large and involatile to pass through the GC column. The major components observed in the pyrolysis-gas chromatography/mass spectrometry of the two heavy fractions were alkanes and alkenes, ranging between C10-C25. Since none of the samples contained free alkanes, alkenes or cycloalkanes before pyrolysis, they were generated during the pyrolysis step. The shifts of UV-fluorescence spectral intensity to shorter wavelengths with decreasing size indicated by size exclusion chromatography (SEC) provide direct evidence of differences in structure with changing molecular mass. This evidence strongly suggests that species identified as being of large molecular mass in this extract sample are not composed of molecular aggregates. It remains difficult to establish whether and when it would be legitimate to invoke molecular aggregates to explain the large

  5. Quantification of trans-1,4-polyisoprene in Eucommia ulmoides by fourier transform infrared spectroscopy and pyrolysis-gas chromatography/mass spectrometry.

    PubMed

    Takeno, Shinya; Bamba, Takeshi; Nakazawa, Yoshihisa; Fukusaki, Eiichiro; Okazawa, Atsushi; Kobayashi, Akio

    2008-04-01

    Commercial development of trans-1,4-polyisoprene from Eucommia ulmoides Oliver (EU-rubber) requires specific knowledge on selection of high-rubber-content lines and establishment of agronomic cultivation methods for achieving maximum EU-rubber yield. The development can be facilitated by high-throughput and highly sensitive analytical techniques for EU-rubber extraction and quantification. In this paper, we described an efficient EU-rubber extraction method, and validated that the accuracy was equivalent to that of the conventional Soxhlet extraction method. We also described a highly sensitive quantification method for EU-rubber by Fourier transform infrared spectroscopy (FT-IR) and pyrolysis-gas chromatography/mass spectrometry (PyGC/MS). We successfully applied the extraction/quantification method for study of seasonal changes in EU-rubber content and molecular weight distribution.

  6. Pyrolysis-high resolution gas chromatography and pyrolysis gas chromatography-mass spectrometry of kerogens and kerogen precursors

    NASA Technical Reports Server (NTRS)

    Van De Meent, D.; Brown, S. C.; Philp, R. P.; Simoneit, B. R. T.

    1980-01-01

    A series of kerogens and kerogen precursors isolated from DSDP samples, oil shales and recent algal mats have been examined by Curie point pyrolysis-high resolution gas chromatography and gas chromatography-mass spectrometry. This study has shown that the three main types of kerogens (marine, terrestrial and mixtures of both) can be characterized using these techniques. The marine (algal) kerogens yield principally aliphatic products and the terrestrial kerogens yield more aromatic and phenolic products with some n-alkanes and n-alkenes. The yields of n-alkanes and n-alkenes increase and phenols decrease with increasing geologic age, however, pyrolysis-GC cannot be used to characterize the influence of short term diagenesis on the kerogen structure.

  7. Pyrolysis-high resolution gas chromatography and pyrolysis gas chromatography-mass spectrometry of kerogens and kerogen precursors

    NASA Technical Reports Server (NTRS)

    Van De Meent, D.; Brown, S. C.; Philp, R. P.; Simoneit, B. R. T.

    1980-01-01

    A series of kerogens and kerogen precursors isolated from DSDP samples, oil shales and recent algal mats have been examined by Curie point pyrolysis-high resolution gas chromatography and gas chromatography-mass spectrometry. This study has shown that the three main types of kerogens (marine, terrestrial and mixtures of both) can be characterized using these techniques. The marine (algal) kerogens yield principally aliphatic products and the terrestrial kerogens yield more aromatic and phenolic products with some n-alkanes and n-alkenes. The yields of n-alkanes and n-alkenes increase and phenols decrease with increasing geologic age, however, pyrolysis-GC cannot be used to characterize the influence of short term diagenesis on the kerogen structure.

  8. Development and Application of Pyrolysis Gas Chromatography/Mass Spectrometry for the Analysis of Bound Trinitrotoluene Residues in Soil

    USGS Publications Warehouse

    Weiss, J.M.; Mckay, A.J.; Derito, C.; Watanabe, C.; Thorn, K.A.; Madsen, E.L.

    2004-01-01

    TNT (trinitrotoluene) is a contaminant of global environmental significance, yet determining its environmental fate has posed longstanding challenges. To date, only differential extraction-based approaches have been able to determine the presence of covalently bound, reduced forms of TNT in field soils. Here, we employed thermal elution, pyrolysis, and gas chromatography/mass spectrometry (GC/MS) to distinguish between covalently bound and noncovalently bound reduced forms of TNT in soil. Model soil organic matter-based matrixes were used to develop an assay in which noncovalently bound (monomeric) aminodinitrotoluene (ADNT) and diaminonitrotoluene (DANT) were desorbed from the matrix and analyzed at a lower temperature than covalently bound forms of these same compounds. A thermal desorption technique, evolved gas analysis, was initially employed to differentiate between covalently bound and added 15N-labeled monomeric compounds. A refined thermal elution procedure, termed "double-shot analysis" (DSA), allowed a sample to be sequentially analyzed in two phases. In phase 1, all of an added 15N-labeled monomeric contaminant was eluted from the sample at relatively low temperature. In phase 2 during high-temperature pyrolysis, the remaining covalently bound contaminants were detected. DSA analysis of soil from the Louisiana Army Ammunition Plant (LAAP; ???5000 ppm TNT) revealed the presence of DANT, ADNT, and TNT. After scrutinizing the DSA data and comparing them to results from solvent-extracted and base/acid-hydrolyzed LAAP soil, we concluded that the TNT was a noncovalently bound "carryover" from phase 1. Thus, the pyrolysis-GC/MS technique successfully defined covalently bound pools of ADNT and DANT in the field soil sample.

  9. Simultaneous trace identification and quantification of common types of microplastics in environmental samples by pyrolysis-gas chromatography-mass spectrometry.

    PubMed

    Fischer, Marten; Scholz-Böttcher, Barbara M

    2017-04-09

    The content of microplastics (MP) in the environment is constantly growing. Since the environmental relevance, particularly bioavailability, rises with decreasing particle size, the knowledge of the MP proportion in habitats and organisms is of gaining importance. The reliable recognition of MP particles is limited and underlies substantial uncertainties. Therefor spectroscopically methods are necessary to ensure the plastic nature of isolated particles, determine the polymer type and obtain particle count related quantitative data. In this study Curie-Point pyrolysis-gas chromatography-mass spectrometry combined with thermochemolysis is shown to be an excellent analytical tool to simultaneously identify and optionally quantify MP in environmental samples on a polymer specific mass related trace level. The method is independent of any optical preselection or particle appearance. For this purpose polymer characteristic pyrolysis products and their indicative fragment ions were used to analyze eight common types of plastics. Further aspects of calibration, recoveries, and potential matrix effects are discussed. The method is exemplarily applied on selected fish samples after an enzymatic-chemically pretreatment. This new approach with mass-related results is complementary to established FT-IR and Raman methods providing particle counts of individual polymer particles.

  10. Pyrolysis kinetic and product analysis of different microalgal biomass by distributed activation energy model and pyrolysis-gas chromatography-mass spectrometry.

    PubMed

    Yang, Xuewei; Zhang, Rui; Fu, Juan; Geng, Shu; Cheng, Jay Jiayang; Sun, Yuan

    2014-07-01

    To assess the energy potential of different microalgae, Chlorella sorokiniana and Monoraphidium were selected for studying the pyrolytic behavior at different heating rates with the analytical method of thermogravimetric analysis (TG), distributed activation energy model (DAEM) and pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS). Results presented that Monoraphidium 3s35 showed superiority for pyrolysis at low heating rate. Calculated by DAEM, during the conversion rate range from 0.1 to 0.7, the activation energies of C. sorokiniana 21 were much lower than that of Monoraphidium 3s35. Both C. sorokiniana 21 and Monoraphidium 3s35 can produce certain amount (up to 20.50%) of alkane compounds, with 9-Octadecyne (C18H34) as the primary compound. Short-chain alkanes (C7-C13) with unsaturated carbon can be released in the pyrolysis at 500°C for both microalgal biomass. It was also observed that the pyrolysis of C. sorokiniana 21 released more alcohol compounds, while Monoraphidium 3s35 produced more saccharides.

  11. Identification and characterization of vinylpyrrolidone-vinylimidazolium chloride copolymers in cosmetic products by pyrolysis-gas chromatography-mass spectrometry method.

    PubMed

    Gmahl, E; Ruess, W

    1993-04-01

    Synopsis Commercially available copolymers of 1-vinyl-2-pyrrolidone and 1-vinyl-3-methylimidazolium chloride, known as 'Luviquat' types in the cosmetic industry, were analysed for their composition using a combination of pyrolysis-gas chromatography-mass spectrometry method. This is a report on the determined pyrolytic products and the fast identification of the analysed polymers both in raw materials and cosmetic products. Calibration with defined material ensures the determination of monomer ratios with good reproducibility. Résumé Les copolymères de chlorure de 1-vinyle-2-pyrolidone et de 1-vinyle-3-methylimidazolium disponibles dans le commerce, connus dans l'industrie cosmétique sous la dénomination de copolymères de vinyle, ont été analysés à laide d'une méthode combinant la pyrolyse, la spectrométrie de mass et la chromatographie en phase gazeuse. Cet article constitue un rapport sur les produits déterminés par pyrolyse et sur la rapidité d'identification des polymères analysés à la fois dans des matières premières et dans des produits cosmétiques. Le calibrage avec un matériel défini assure une bonne détermination des taux de monomères dotés d'une reproductibilité.

  12. Molecular characterisation of a bio-based active packaging containing Origanum vulgare L. essential oil using pyrolysis gas chromatography-mass spectrometry.

    PubMed

    Llana-Ruíz-Cabello, María; Pichardo, Silvia; Jiménez-Morillo, Nicasio T; Bermúdez, José M; Aucejo, Susana; González-Vila, Francisco J; Cameán, Ana M; González-Pérez, José A

    2016-07-01

    Environmental, economic and safety challenges motivate shift towards safer materials for food packaging. New bioactive packaging techniques, i.e. addition of essential plant oils (EOs), are gaining attention by creating barriers to protect products from spoilage. Analytical pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) was used to fingerprint a bioactive polylactic acid (PLA) with polybutylene succinate (PBS) (950 g kg(-1) :50 g kg(-1) ) film extruded with variable quantities (0, 20, 50 and 100 g kg(-1) ) of Origanum vulgare EO. Main PLA:PBS pyrolysis products were lactide enantiomers and monomer units from the major PLA fraction and succinic acid anhydride from the PBS fraction. Oregano EO pyrolysis released cymene, terpinene and thymol/carvacrol peaks as diagnostic peaks for EO. In fact, linear correlation coefficients better than 0.950R(2) value (P < 0.001) were found between the chromatographic area of the diagnostic peaks and the amount of oregano EO in the bioplastic. The pyrolytic behaviour of a bio-based active package polymer including EO is studied in detail. Identified diagnostic compounds provide a tool to monitor the quantity of EO incorporated into the PLA:PBS polymeric matrix. Analytical pyrolysis is proposed as a rapid technique for the identification and quantification of additives within bio-based plastic matrices. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  13. Molecular characterisation of organic material in air fine particles (PM10) using conventional and reactive pyrolysis-gas chromatography-mass spectrometry.

    PubMed

    Fabbri, Daniele; Prati, Silvia; Vassura, Ivano

    2002-04-01

    Pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) was applied to study the composition of organic constituents in air particulate matter (PM10) collected inside an industrial area. A few milligrams of sampling filters containing air particles were pyrolysed at 700 degrees C directly (conventional) or after the addition of a derivatising reagent (tetramethylammonium hydroxide, TMAH, for pyrolysis-methylation; hexamethyldisilazane, HMDS, for pyrolysis-silylation). Py-GC-MS was also applied to synthetic polymers (poly(styrene-co-isoprene), polylimonene and polypinene) and vegetation samples (coniferous pollen, bark and resin) to identify markers indicative of possible precursors. Pyrolysates of PM10 showed the same suite of compounds in all the four seasons, dominated by hydrocarbons like styrene, limonene and clusters of isomeric alkenes with 14, 15 and 16 carbon atoms. Pyrolysis products of natural origin, including furaldehyde, benzeneacetonitrile, dehydroabietin and other diterpenoids were found, while no specific markers of synthetic rubbers were detected. The principal products released from reactive pyrolysis of PM10 were methyl or trimethylsilyl (TMS) derivatives of 1,6-anhydroglucose (levoglucosan), fatty acids, dehydroabietic acid and other resin acids along with hydroxy (di)carboxylic acids. Possible sources of the detected products (e.g. pine forest, biomass combustion) are discussed.

  14. Pyrolysis/gas chromatography/mass spectrometry of a series of buried woods and coalified logs that increase in rank from peat to subbituminous coal

    SciTech Connect

    Hatcher, P.G.; Lerch, H.E. III; Verheyen, T.V.

    1987-04-01

    To better understand the coalification process, the authors have conducted numerous studies of the chemical structural composition of xylem tissue from gymnosperm wood and related woods that has been coalified to varying degrees. The studies presented in this paper examine the chemical nature of buried and coalified xylem tissue at the molecular level. To achieve this, the authors employed pyrolysis/gas chromatography (py/gc) and pyrolysis/gas chromotography/mass spectrometry (py/gc/ms). Pyrolysis techniques have been used to examine peat, coal, coalified wood, and related substances.

  15. Assessment of the degradation of polyurethane foams after artificial and natural ageing by using pyrolysis-gas chromatography/mass spectrometry and headspace-solid phase microextraction-gas chromatography/mass spectrometry.

    PubMed

    Lattuati-Derieux, A; Thao-Heu, S; Lavédrine, B

    2011-07-15

    Polyurethane foams are widely present in museum collections either as part of the artefacts, or as a material for their conservation. Unfortunately many of PU foam artefacts are in poor condition and often exhibit specific conservation issues. Their fast thermal and photochemical degradations have been the aim of previous researches. It is now accepted that hydrolysis predominates for polyester-based polyurethane PU(ES) whereas oxidation is the principal cause of degradation for polyether-based polyurethane PU(ET) variety. Only a few studies have been devoted to volatile organic compounds (VOCs) emitted by polyurethanes and, to our knowledge, none were performed on polyurethane foams by using headspace-solid phase microextraction (HS-SPME). The objective of the work described here is to assess the impact of some environmental factors (humidity, temperature and daylight) on the degradation of PU foams by evaluating their volatile fractions. We investigated morphological changes, polymerized fractions and volatile fractions of (i) one modern produced PU(ES) foam and one modern PU(ET) foam artificially aged in different conditions as well as (ii) four naturally aged foams collected from various daily life objects and selected for the representativeness of their analytical data. Characterization procedure used was based on attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and non-invasive headspace solid-phase microextraction coupled with gas chromatography and mass spectrometry (HS-SPME-GC/MS). In this paper, the formation of alcohol and acid raw products for PU(ES) and glycol derivatives for PU(ET) during natural and artificial ageing is confirmed. These main products can be considered as degradation markers for PU foams. Results show that artificial and natural ageing provide similar analytical results, and confirm that the dominant degradation paths for PU(ES) and for PU(ET) are

  16. Identification and hazard prediction of tattoo pigments by means of pyrolysis-gas chromatography/mass spectrometry.

    PubMed

    Schreiver, Ines; Hutzler, Christoph; Andree, Sarah; Laux, Peter; Luch, Andreas

    2016-07-01

    The implementation of regulation for tattoo ink ingredients across Europe has generated the need for analytical methods suitable to identify prohibited compounds. Common challenges of this subject are the poor solubility and the lack of volatility for most pigments and polymers applied in tattoo inks. Here, we present pyrolysis coupled to online gas chromatography and electron impact ionization mass spectrometry (py-GC/MS) as quick and reliable tool for pigment identification using both purified pigments and tattoo ink formulations. Some 36 organic pigments frequently used in tattoo inks were subjected to py-GC/MS with the aim to establish a pyrogram library. To cross-validate pigment identification, 28 commercially available tattoo inks as well as 18 self-made pigment mixtures were analyzed. Pyrograms of inks and mixtures were evaluated by two different means to work out the most reliable and fastest strategy for an otherwise rather time-consuming data review. Using this approach, the declaration of tattoo pigments currently used on the market could be verified. The pyrolysis library presented here is also assumed suitable to predict decomposition patterns of pigments when affected by other degradation scenarios, such as sunlight exposure or laser irradiation. Thus, the consumers' risk associated with the exposure to toxicologically relevant substances that originate from pigment decomposition in the dermal layers of the skin can be assessed. Differentiation between more or less harmful pigments for this field of application now will become feasible.

  17. High-throughput characterization of sediment organic matter by pyrolysis-gas chromatography/mass spectrometry and multivariate curve resolution: A promising analytical tool in (paleo)limnology.

    PubMed

    Tolu, Julie; Gerber, Lorenz; Boily, Jean-François; Bindler, Richard

    2015-06-23

    Molecular-level chemical information about organic matter (OM) in sediments helps to establish the sources of OM and the prevalent degradation/diagenetic processes, both essential for understanding the cycling of carbon (C) and of the elements associated with OM (toxic trace metals and nutrients) in lake ecosystems. Ideally, analytical methods for characterizing OM should allow high sample throughput, consume small amounts of sample and yield relevant chemical information, which are essential for multidisciplinary, high-temporal resolution and/or large spatial scale investigations. We have developed a high-throughput analytical method based on pyrolysis-gas chromatography/mass spectrometry and automated data processing to characterize sedimentary OM in sediments. Our method consumes 200 μg of freeze-dried and ground sediment sample. Pyrolysis was performed at 450°C, which was found to avoid degradation of specific biomarkers (e.g., lignin compounds, fresh carbohydrates/cellulose) compared to 650°C, which is in the range of temperatures commonly applied for environmental samples. The optimization was conducted using the top ten sediment samples of an annually resolved sediment record (containing 16-18% and 1.3-1.9% of total carbon and nitrogen, respectively). Several hundred pyrolytic compound peaks were detected of which over 200 were identified, which represent different classes of organic compounds (i.e., n-alkanes, n-alkenes, 2-ketones, carboxylic acids, carbohydrates, proteins, other N compounds, (methoxy)phenols, (poly)aromatics, chlorophyll and steroids/hopanoids). Technical reproducibility measured as relative standard deviation of the identified peaks in triplicate analyses was 5.5±4.3%, with 90% of the RSD values within 10% and 98% within 15%. Finally, a multivariate calibration model was calculated between the pyrolytic degradation compounds and the sediment depth (i.e., sediment age), which is a function of degradation processes and changes in OM

  18. PYROLYSIS/GAS CHROMATOGRAPHY/MASS SPECTROMETRY OF A SERIES OF BURIED WOODS AND COALIFIED LOGS THAT INCREASE IN RANK FROM PEAT TO SUBBITUMINOUS COAL.

    USGS Publications Warehouse

    Hatcher, Patrick G.; Lerch, Harry E.; Kotra, Rama K.; Verheyen, Vincent T.

    1987-01-01

    To better understand the coalification process, we have conducted numerous studies of the chemical structural composition of xylem tissue from gymosperm wood and related woods that has been coalified to varying degrees. The studies presented here, examine the chemical nature of buried and coalified xylem tissue at the molecular level. To achieve this, we employed pyrolysis/gas chromatography (py/gc) and pyrolysis/gas chromotography/mass spectrometry (py/gc/ms). Pyrolysis techniques have been used to examine peat, coal, coalified wood, and related substances. However, the technique has not been previously applied to a systematic and histologically-related series of coalified woods. It is particularly useful to compare the results from pyrolytic studies with the data obtained from solid-state **1**3C NMR.

  19. Pyrolysis-gas chromatography-mass spectrometry for studying N-vinyl-2-pyrrolidone-co-vinyl acetate copolymers and their dissolution behaviour.

    PubMed

    Chojnacka, Aleksandra; Ghaffar, Abdul; Feilden, Andrew; Treacher, Kevin; Janssen, Hans-Gerd; Schoenmakers, Peter

    2011-11-14

    Knowledge on the solubility behaviour and dissolution rate of speciality and commodity polymers is very important for the use of such materials in high-tech applications. We have developed methods for the quantification and characterization of dissolved copolymers of N-vinyl-2-pyrrolidone (VP) and vinyl acetate (VA) during dissolution in water. The methods are based on pyrolysis (Py) performed in a programmed-temperature vaporization injector with subsequent identification and quantification of the components in the pyrolysate using capillary gas chromatography-mass spectrometry (GC-MS). By injecting large volumes and applying cryo-focussing at the top of the column, low detection limits could be achieved. The monomer ratio was found to have the greatest effect on the dissolution rate of the PVP-co-VA copolymers. The material with the highest amount of VA (50%) dissolves significantly slower than the other grades. Size-exclusion chromatography (SEC) and Py-GC-MS were used to measure molecular weights and average chemical compositions, respectively. Combined off-line SEC//Py-GC-MS was used to determine the copolymer composition (VP/VA ratio), as a function of the molecular weight for the pure polymers. In the dissolution experiments, a constant VP/VA ratio across the dissolution curve was observed for all copolymers analysed. This suggests a random distribution of the two monomers over the molecules.

  20. Variation in cell wall composition among forage maize (Zea mays L.) inbred lines and its impact on digestibility: analysis of neutral detergent fiber composition by pyrolysis-gas chromatography-mass spectrometry.

    PubMed

    Fontaine, Anne-Sophie; Bout, Siobhán; Barrière, Yves; Vermerris, Wilfred

    2003-12-31

    Cell wall digestibility is an important determinant of forage quality, but the relationship between cell wall composition and digestibility is poorly understood. We analyzed the neutral detergent fiber (NDF) fraction of nine maize inbred lines and one brown midrib3 mutant with pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). Among 29 pyrolysis fragments that were quantified, two carbohydrate-derived and six lignin-derived fragments showed statistically significant genetic variation. The pyrolysis products 4-vinyl phenol and 2,6-dimethoxy-4-vinyl phenol were negatively correlated with digestibility, whereas furfural and 3-(4-hydroxyphenyl)-3-oxopropanal showed a positive correlation with digestibility. Linear discriminant analysis of the pyrolysis data resulted in the resolution of groups of inbred lines with different digestibility properties based on their chemical composition. These analyses reveal that digestibility is governed by complex interactions between different cell wall compounds, but that several pyrolysis fragments can be used as markers to distinguish between maize lines with different digestibility.

  1. Application of pyrolysis-gas chromatography-mass spectrometry and multivariate analysis to study bacteria and fungi in biofilms used for bioremediation.

    PubMed

    Melucci, Dora; Fedi, Stefano; Locatelli, Marcello; Locatelli, Clinio; Montalbani, Simona; Cappelletti, Martina

    2013-08-01

    Biofilms are communities of microorganisms adhering to a surface and embedded in an extracellular polymeric matrix, frequently associated with disease and contamination, and also used for engineering applications such as bioremediation. A mixed biofilm formed by bacteria and fungi may provide an optimal habitat for addressing contaminated areas. To exploit the potential of natural microbial communities consisting of bacteria and fungi, it is essential to understand and control their formation. In this work, a method to discriminate among bacteria of genera Bacillus, Pseudomonas, Rhodococcus with respect to the fungus Pleorotus in a biofilm by means of pyrolysis-gaschromatography-mass spectrometry and multivariate analysis is reported. Methylated fatty acids were chosen as biomarkers of microorganisms in the pyrolysates. In situ thermal hydrolysis and methylation was applied. Pyrograms were used as fingerprints, thus allowing for the characterization of whole cells analyzed without any sample pretreatment. Normalized pyrographic peak areas were chosen as variables for chemometric data processing. Principal components analysis was applied as a data exploration tool. Satisfactory results were obtained in analyzing a real biofilm. The influence of growth medium on whole bacteria fatty acid cell composition was also explored.

  2. Pyrolysis-Gas Chromatography/Mass Spectrometry of Thermoplastic Polymers

    DTIC Science & Technology

    1988-04-01

    The pyrogram at 1000 C contained a number of other peaks including benzonitrile - (scan 274), methylbenzonitrile (scans 324, 335), methylaniline...and benzonitriles and the formation of higher molecular weight compounds, such as biphenyl, benzo[H~quinoline and benzo[C]cinnoline, from...triene 274/--- benzonitrile 324/ --- methylbenzonitrile (also 335) 330/ --- iethylaniline 342/--- isocyano-4-methylbenzene 391/ --- naphthalene 436

  3. Liquid Chromatography Mass Spectrometry Profiling of Histones

    PubMed Central

    Su, Xiaodan; Jacob, Naduparambil K.; Amunugama, Ravindra; Lucas, David M.; Knapp, Amy R.; Ren, Chen; Davis, Melanie E.; Marcucci, Guido; Parthun, Mark R.; Byrd, John C.; Fishel, Richard A.; Freitas, Michael A.

    2007-01-01

    Here we describe the use of reverse-phase liquid chromatography mass spectrometry (RP-LC-MS) to simultaneously characterize variants and post-translationally modified isoforms for each histone. The analysis of intact proteins significantly reduces the time of sample preparation and simplifies data interpretation. LC-MS analysis and peptide mass mapping have previously been applied to identify histone proteins and to characterize their post-translational modifications. However, these studies provided limited characterization of both linker histones and core histones. The current LC-MS analysis allows for the simultaneous observation of all histone PTMs and variants (both replacement and bulk histones) without further enrichment, which will be valuable in comparative studies. Protein identities were verified by the analysis of histone H2A species using RPLC fractionation, AU-PAGE separation and nano-LC-MS/MS. PMID:17254850

  4. Liquid Chromatography-Mass Spectrometry-based Quantitative Proteomics

    SciTech Connect

    Xie, Fang; Liu, Tao; Qian, Weijun; Petyuk, Vladislav A.; Smith, Richard D.

    2011-07-22

    Liquid chromatography-mass spectrometry (LC-MS)-based quantitative proteomics has become increasingly applied for a broad range of biological applications due to growing capabilities for broad proteome coverage and good accuracy in quantification. Herein, we review the current LC-MS-based quantification methods with respect to their advantages and limitations, and highlight their potential applications.

  5. Specialized Gas Chromatography--Mass Spectrometry Systems for Clinical Chemistry.

    ERIC Educational Resources Information Center

    Gochman, Nathan; And Others

    1979-01-01

    A discussion of the basic design and characteristics of gas chromatography-mass spectrometry systems used in clinical chemistry. A comparison of three specific systems: the Vitek Olfax IIA, Hewlett-Packard HP5992, and Du Pont DP-102 are included. (BB)

  6. Specialized Gas Chromatography--Mass Spectrometry Systems for Clinical Chemistry.

    ERIC Educational Resources Information Center

    Gochman, Nathan; And Others

    1979-01-01

    A discussion of the basic design and characteristics of gas chromatography-mass spectrometry systems used in clinical chemistry. A comparison of three specific systems: the Vitek Olfax IIA, Hewlett-Packard HP5992, and Du Pont DP-102 are included. (BB)

  7. Potential biomarkers of smoked fentanyl utilizing pyrolysis gas chromatography-mass spectrometry.

    PubMed

    Nishikawa, Rona K; Bell, Suzanne C; Kraner, James C; Callery, Patrick S

    2009-10-01

    Fentanyl is a potent opioid analgesic that is increasingly becoming a choice drug of abuse. Fentanyl transdermal patches (FTPs) are easily obtained and consumed by smoking the reservoir gel and/or the whole patch. This allows for an increased bioavailability when inhaled. A method using analytical pyrolysis was developed to identify possible biomarkers associated with smoked fentanyl and FTPs. Pyrolysis was carried out under anaerobic and aerobic conditions using helium and air coupled to a gas chromatograph-mass spectrometer. The presence of a trap enhanced recovery and afforded a positive identification of pyrolytic products. Anaerobic and aerobic pyrolysis of fentanyl and FTPs consistently yielded propionanilide as the major pyrolytic product along with pyridine and previously reported metabolites (norfentanyl and despropionyl fentanyl). Analysis of fentanyl resulted in chlorine-containing compounds, presumably formed from the HCl salt of fentanyl. Analysis of FTPs showed significant polymeric and hydrocarbon compounds and products likely derived from the gel matrix. Fentanyl in the FTPs was in the citrate salt form; therefore, the chlorine-containing pyrolytic products obtained with the neat drug were not observed. Based on this application, it may be possible to identify what salt form of the drug was smoked based on pyrolytic products and to target distinguishing metabolic products for future research.

  8. Cortisol production rates measured by liquid chromatography/mass spectrometry

    SciTech Connect

    Esteban, N.V.; Yergey, A.L. )

    1990-04-01

    Cortisol production rates (FPRs) in physiologic and pathologic states in humans have been investigated over the past 30 years. However, there has been conflicting evidence concerning the validity of the currently accepted value of FPRs in humans (12 to 15 mg/m2/d) as determined by radiotracer methodology. The present study reviews previous methods proposed for the measurement of FPRs in humans and discusses the applications of the first method for the direct determination of 24-hour plasma FPRs during continuous administration of a stable isotope, using a thermospray high-pressure liquid chromatography-mass spectrometry technique. The technique is fast, sensitive, and, unlike gas chromatography-mass spectrometry methods, does not require derivatization, allowing on-line detection and quantification of plasma cortisol after a simple extraction procedure. The results of determination of plasma FPRs by stable tracer/mass spectrometry are directly in units of mass/time and, unlike radiotracer methods, are independent of any determination of volume of distribution or cortisol concentration. Our methodology offers distinct advantages over radiotracer techniques in simplicity and reliability since only single measurements of isotope ratios are required. The technique was validated in adrenalectomized patients. Circadian variations in daily FRPs were observed in normal volunteers, and, to date, results suggest a lower FRP in normal children and adults than previously believed. 88 references.

  9. Classification of natural resins by liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry using chemometric analysis.

    PubMed

    Rhourrhi-Frih, B; West, C; Pasquier, L; André, P; Chaimbault, P; Lafosse, M

    2012-09-21

    Twenty-six resins from six botanical sources belonging to the class Magnoliopsida were compared based on gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry data. The extracts were analysed by GC after silylation and by reversed phase LC combined with atmospheric pressure photoionisation (APPI) mass spectrometry. The chromatograms were re-organized in data matrices, where each sample was represented by a single column comprising 2755 observations (intensity, time, m/z) in GC-MS and 360 observations in LC-MS. A simple comparison of resin fingerprints was attempted by organizing data according to a three dimensional bubble chart (retention time against m/z where each point was a bubble which size represented the ion intensity) where it is possible to easily superimpose the fingerprints. Thus the common and different species can be easily observed enabling to classify the resins. Hierarchical cluster analysis based on characteristics of GC-MS and LC-MS profiles affords a complete description of the classes of the resins and shows that 26 resins are divided into five main clusters Commiphora mukul, Daniella oliveri, Gardenia gummifera, Canarium madagascariensis, Boswellia dalzielii and Boswellia serrata, respectively. In conclusion, the proposed method has been applied to three other resinous samples from the Burseraceae family to evaluate their alteration state.

  10. Direct analysis of oligomeric tackifying resins in rubber compounds by automatic thermal desorption gas chromatography/mass spectrometry

    PubMed

    Kim

    1999-01-01

    Two analytical methods, automatic thermal desorption gas chromatography/mass spectrometry (ATD-GC/MS) and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS), were applied as direct methods for the analysis of oligomeric tackifying resins in a vulcanized rubber. The ATD-GC/MS method, based on discontinuous volatile extraction, was found to be an effective means for direct analysis of the oligomeric tackifying resins contained in a vulcanized rubber. The oligomeric tackifying resins, such as t-octylphenolformaldehyde (TOPF) resin, rosin-modified terpene resin, and cashew resin, could be directly analyzed in vulcanized rubber by ATD-GC/MS. Much simpler total ion chromatograms were obtained by ATD-GC/MS than by flash pyrolysis with a Curie-point pyrolyzer, permitting much easier interpretation. Ions at m/z 206, 135, and 107 were fingerprints in the characteristic mass spectra obtained by ATD-GC/MS for TOPF resin in the vulcanized rubber. 1H-Indene, styrene, and isolongifolene were observed as their characteristic mass spectra in the pyrolyzate of the rosin-modified terpene resin. From the cashew resin, phenol, 3-methylphenol, and 4-(1,1,3, 3-tetramethylbutyl)phenol were obtained as the characteristic pyrolyzates by discontinuous thermal extraction via ATD-GC/MS. Copyright 1999 John Wiley & Sons, Ltd.

  11. Identification of polychlorinated styrene compounds in heron tissues by gas-liquid chromatography-mass spectrometry.

    PubMed

    Reichel, W L; Prouty, R M; Gay, M L

    1977-01-01

    Unknown compounds detected in Ardea herodias tissues are identified by gas-liquid chromatography-mass spectrometry as residues of octachlorostyrene. Heptachlorostyrene and hexachlorostyrene were tentatively identified.

  12. Identification of polychlorinated styrene compounds in heron tissues by gas-liquid chromatography-mass spectrometry

    USGS Publications Warehouse

    Reichel, W.L.; Prouty, R.M.; Gay, M.L.

    1977-01-01

    Unknown compounds detected in Ardea herodias tissues are identified by gas-liquid chromatography-mass spectrometry as residues of octachlorostyrene. Heptachlorostyrene and hexachlorostyrene were tentatively identified.

  13. Field gas chromatography-mass spectrometry for fast analysis.

    PubMed

    Makas, Alexei L; Troshkov, Mikhail L

    2004-02-05

    The objective of this presentation is to demonstrate the original device and procedure for fast gas chromatography-mass spectrometry (GC-MS) analysis of gaseous and liquid samples and to discuss its features and capabilities. The concept was developed in order to expand the range of compounds suitable for GC separation and to reduce the time of analysis. Field GC-MS, consisting of original "concentrator-thermodesorber" (CTD) unit, multiple module GC system and compact magnetic mass spectrometer with powerful two-stage vacuum system and multicollector ion detector, is represented. The whole weight of the device is 90 kg. Power consumption is 250 W. The device and analytical procedures allow high speed screening of toxic substances in air and extracts within 100 s per sample. The examples of applications are described, including fast screening of tributyl phosphate (TBP) in air at low ppt level at the rate 1 sample/min.

  14. Estimation of brassylic acid by gas chromatography-mass spectrometry

    SciTech Connect

    Mohammed J. Nasrullah, Erica N. Pfarr, Pooja Thapliyal, Nicholas S. Dusek, Kristofer L. Schiele, Christy Gallagher-Lein, and James A. Bahr

    2010-10-29

    The main focus of this work is to estimate Brassylic Acid (BA) using gas chromatography-mass spectrometry (GC-MS). BA is a product obtained from the oxidative cleavage of Erucic Acid (EA). BA has various applications for making nylons and high performance polymers. BA is a 13 carbon compound with two carboxylic acid functional groups at the terminal end. BA has a long hydrocarbon chain that makes the molecule less sensitive to some of the characterization techniques. Although BA can be characterized by NMR, both the starting material (EA) and products BA and nonanoic acid (NA) have peaks at similar {delta}, ppm values. Hence it becomes difficult for the quick estimation of BA during its synthesis.

  15. Quantification of antidepressants using gas chromatography-mass spectrometry.

    PubMed

    Winecker, Ruth E

    2010-01-01

    Antidepressants are of great interest to clinical and forensic toxicologists as they are frequently used in suicidal gestures; they can be the source of drug interactions and some have narrow therapeutic indices making the potential for toxicity more likely. There are five categories of antidepressants based on function and/or structure. These are monoamine oxidase inhibitors (MAOI), cyclic antidepressants including tricyclic and tetracyclic compounds (TCA), selective serotonin reuptake inhibitors (SSRI), serotonin-norepinephrine reuptake inhibitors (SNRI), and atypical compounds. This method is designed to detect the presence of antidepressant drugs in blood/serum, urine, and tissue specimens using gas chromatography/mass spectrometry (GC/MS) following liquid-liquid extraction (LLE) and identified by relative retention times and mass spectra.

  16. Determination of ink photoinitiators in packaged beverages by gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry.

    PubMed

    Sagratini, Gianni; Caprioli, Giovanni; Cristalli, Gloria; Giardiná, Dario; Ricciutelli, Massimo; Volpini, Rosaria; Zuo, Yanting; Vittori, Sauro

    2008-06-20

    A new analytical method, using gas chromatography-mass spectrometry (GC/MS) and liquid chromatography-mass spectrometry (LC/MS) techniques, was developed for the determination in packaged food beverages of five ink photoinitiator residues: 2-isopropylthioxanthone (ITX), benzophenone, 2-ethylhexyl-4-dimethylaminobenzoate (EHDAB), 1-hydroxycyclohexyl-1-phenyl ketone (IRGACURE 184) and ethyl-4-dimethylaminobenzoate (EDAB). Samples were extracted from selected beverages (milk, fruit juices and wine) and relative packagings, using n-hexane and dichloromethane, respectively, purified on solid-phase extraction (SPE) silica gel cartridges, and then analyzed in GC/MS and LC/MS. The recovery percentages, obtained spiking the beverage samples at concentrations of 4 and 10 microgl(-1) with a standard mixture of photoinitiators, were in the range 42-108% (milk), 50-84% (wine), and 48-109% (fruit juices). The repeatability of the method was assessed in all cases by the % of correlation value, that was lower than 19%. The lowest limits of detection (LODs) and limits of quantification (LOQs), obtained using GC/MS, were in the range 0.2-1 and 1-5 microgl(-1), respectively. The method was applied to the analysis of forty packaged food beverages (milk, fruit juices and wine samples). The most significant contamination was that of benzophenone, found in all samples in a concentration range of 5-217mugl(-1). Its presence was confirmed by an LC/Atmospheric-Pressure PhotoIonization (APPI)/MS/MS analysis. The photoinitiator (EHDAB) was found in eleven out of forty beverages in a concentration range of 0.13-0.8 microgl(-1). Less important was the ITX contamination, found in three out of forty samples in a range 0.2-0.24 microgl(-1). The work proposes a new method to analyze ink photoinitiator residues in polycoupled carton packaging and in contained food beverages.

  17. Steroid profiling by gas chromatography-mass spectrometry and high performance liquid chromatography-mass spectrometry for adrenal diseases.

    PubMed

    McDonald, Jeffrey G; Matthew, Susan; Auchus, Richard J

    2011-12-01

    The ability to measure steroid hormone concentrations in blood and urine specimens is central to the diagnosis and proper treatment of adrenal diseases. The traditional approach has been to assay each steroid hormone, precursor, or metabolite using individual aliquots of serum, each with a separate immunoassay. For complex diseases, such as congenital adrenal hyperplasia and adrenocortical cancer, in which the assay of several steroids is essential for management, this approach is time consuming and costly, in addition to using large amounts of serum. Gas chromatography/mass spectrometry profiling of steroid metabolites in urine has been employed for many years but only in a small number of specialized laboratories and suffers from slow throughput. The advent of commercial high-performance liquid chromatography instruments coupled to tandem mass spectrometers offers the potential for medium- to high-throughput profiling of serum steroids using small quantities of sample. Here, we review the physical principles of mass spectrometry, the instrumentation used for these techniques, the terminology used in this field and applications to steroid analysis.

  18. Gas chromatography-mass spectrometry of biofluids and extracts.

    PubMed

    Emwas, Abdul-Hamid M; Al-Talla, Zeyad A; Yang, Yang; Kharbatia, Najeh M

    2015-01-01

    Gas chromatography-mass spectrometry (GC-MS) has been widely used in metabonomics analyses of biofluid samples. Biofluids provide a wealth of information about the metabolism of the whole body and from multiple regions of the body that can be used to study general health status and organ function. Blood serum and blood plasma, for example, can provide a comprehensive picture of the whole body, while urine can be used to monitor the function of the kidneys, and cerebrospinal fluid (CSF) will provide information about the status of the brain and central nervous system (CNS). Different methods have been developed for the extraction of metabolites from biofluids, these ranging from solvent extracts, acids, heat denaturation, and filtration. These methods vary widely in terms of efficiency of protein removal and in the number of metabolites extracted. Consequently, for all biofluid-based metabonomics studies, it is vital to optimize and standardize all steps of sample preparation, including initial extraction of metabolites. In this chapter, recommendations are made of the optimum experimental conditions for biofluid samples for GC-MS, with a particular focus on blood serum and plasma samples.

  19. Correlation of Mass Spectrometry Identified Bacterial Biomarkers From a Fielded Pyrolysis-Gas Chromatography-Ion Mobility Spectrometry Biodetector With the Microbiological Gram Stain Classification Scheme

    DTIC Science & Technology

    2005-09-01

    BACTERIAL BIOMARKERS FROM A FIELDED PYROLYSIS-GAS CHROMATOGRAPHY- ION MOBILITY SPECTROMETRY BIODETECTOR WITH THE MICROBIOLOGICAL GRAM STAIN ...GRANT NUMBER Microbiological Gram Stain Classification Scheme__________________ Se. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Snyder, A...information that can serve as components of a biological classification scheme directly correlated to the Gram stain reaction in microorganism taxonomy. 3

  20. Analysis of Microorganisms by Oxidative and Non-Oxidative Pyrolysis Gas Chromatography Ion Trap Mass Spectrometry.

    DTIC Science & Technology

    1992-04-01

    Bacillus subtilis, Bacillus pumilus , Bacillus lichenformis, and Bacillus amyloliquefaciens by Pyrolysis-gas Liquid Chromatography, Deoxyribonucleic...FIGURES Number Page 1. Curie point pyrolysis GC-ITD data for Bacillus subtilis ................... 16 2. Total Ion Chromatograms for Bacillus subtilis...under oxidative and non-oxidative pyrolysis conditions ................................... 17 3. Total Lipid Mass Spectra for Bacillus subtilis under

  1. Chemical Composition of Latent Fingerprints by Gas Chromatography-Mass Spectrometry

    ERIC Educational Resources Information Center

    Hartzell-Baguley, Brittany; Hipp, Rachael E.; Morgan, Neal R.; Morgan, Stephen L.

    2007-01-01

    An experiment in which gas chromatography-mass spectrometry (GC-MS) is used for latent fingerprint extraction and analysis on glass beads or glass slides is conducted. The results determine that the fingerprint residues are gender dependent.

  2. Chemical Composition of Latent Fingerprints by Gas Chromatography-Mass Spectrometry

    ERIC Educational Resources Information Center

    Hartzell-Baguley, Brittany; Hipp, Rachael E.; Morgan, Neal R.; Morgan, Stephen L.

    2007-01-01

    An experiment in which gas chromatography-mass spectrometry (GC-MS) is used for latent fingerprint extraction and analysis on glass beads or glass slides is conducted. The results determine that the fingerprint residues are gender dependent.

  3. VACUUM DISTILLATION COUPLED WITH GAS CHROMATOGRAPHY/MASS SPECTROMETRY FOR THE ANALYSIS OF ENVIRONMENTAL SAMPLES

    EPA Science Inventory

    A procedure is presented that uses a vacuum distillation/gas chromatography/mass spectrometry system for analysis of problematic matrices of volatile organic compounds. The procedure compensates for matrix effects and provides both analytical results and confidence intervals from...

  4. VACUUM DISTILLATION COUPLED WITH GAS CHROMATOGRAPHY/MASS SPECTROMETRY FOR THE ANALYSIS OF ENVIRONMENTAL SAMPLES

    EPA Science Inventory

    A procedure is presented that uses a vacuum distillation/gas chromatography/mass spectrometry system for analysis of problematic matrices of volatile organic compounds. The procedure compensates for matrix effects and provides both analytical results and confidence intervals from...

  5. Drug analysis by direct liquid introduction micro liquid chromatography mass spectrometry.

    PubMed

    Henion, J D; Maylin, G A

    1980-03-01

    The analytical capabilities of a micro high performance liquid chromatograph interfaced to an unchanged quadrupole mass spectrometer are presented. Continuous monitoring of the total micro liquid chromatographic effluent allows full scan chemical ionization mass spectra of from one to five nanograms of drugs and their metabolites to be recorded. The interface is a simple, inexpensive device which can be assembled from commercially available components. An eight microliter per minute flow rate of the micro liquid chromatographic eluant allows separation and identification of biologically important substances not amenable to gas chromatography mass spectrometry techniques. The sensitivity of micro liquid chromatography mass spectrometry performed as described is comparable with gas chromatography mass spectrometry and is achieved by introducing the total micro liquid chromatographic effluent into the chemical ionization ion source of the mass spectrometer. Selected ion monitoring provides 20 pg detection limits of phenothiazine tranquilizers injected on column.

  6. Increasing maturity of kerogen type II reflected by alkylbenzene distribution from pyrolysis-gas chromatography-mass spectrometry

    USGS Publications Warehouse

    Lis, G.P.; Mastalerz, Maria; Schimmelmann, A.

    2008-01-01

    A series of Late Devonian to Early Mississippian type II kerogens with vitrinite reflectance values Ro 0.29-2.41% were analyzed using py-GC-MS. In addition, a low maturity kerogen with Ro 0.44% was separated into fractions via density gradient centrifugation, followed by py-GC-MS of the alginite and amorphinite maceral concentrates. Alkylbenzenes and n-alk-1-ene/n-alkane doublets represented the main compound classes identified in all pyrolysates. The pyrolysate from alginite featured 1,2,4-trimethylbenzene and toluene as the two most prominent alkylbenzenes. In contrast, alkylbenzenes in pyrolysates from amorphinite and low maturity bulk kerogens with Ro 0.29-0.63% were dominated by 1,2,3,4-tetramethylbenzene. With increasing thermal maturity, pyrolysates were increasingly dominated by (i) alkylbenzenes with fewer methyl groups, namely by tri- and dimethylbenzenes at medium maturity (Ro 0.69-1.19%), and (ii) by toluene at higher maturity (Ro 1.30-2.41%). With increasing maturity of kerogen type II, the decreasing abundance of highly methyl-substituted alkylbenzenes and the parallel increase in less methyl-substituted alkylbenzenes in flash pyrolysates suggest that demethylation is an important chemical process in the thermal maturation of kerogen type II. ?? 2008 Elsevier Ltd. All rights reserved.

  7. Chemical composition of Titan's aerosols analogues characterized with a systematic pyrolysis-gas chromatography-mass spectrometry characterization

    NASA Astrophysics Data System (ADS)

    Szopa, Cyril; Raulin, Francois; Coll, Patrice; Cabane, Michel; GCMS Team

    2014-05-01

    The in situ chemical characterization of Titan's atmosphere was achieved in 2005 with two instruments present onboard the Huygens atmospheric probe : the Aerosol Collector and Pyrolyzer (ACP) devoted to collect and pyrolyse Titan's aerosols ; the Gas Chromatograph-Mass Spectrometer (GCMS) experiment devoted to analyze gases collected in the atmosphere or coming from the aerosols pyrolysis. The GCMS was developed by Hasso Niemann in the filiation of the quadrupole mass spectrometers he built for several former space missions. The main objectives were to : determine the concentration profile of the most abundant chemical species; seek for minor atmospheric organic species not detected with remote observations ; give a first view of the organic aerosols structure; characterize the condensed volatiles present at the surface (e.g. lakes) in case of survival of the probe to the landing impact. Taking into account for the potential complexity of the gaseous samples to be analyzed, it was decided to couple to the MS analyzer a gas chromatograph capable to separate volatile species from light inorganic molecules and noble gases, to organic compounds including aromatics. This was the first GCMS analyzer that worked in an extraterrestrial environment since the Viking missions on Mars. Even if the GCMS coupling mode did not provide any result of interest, it has been demonstrated to be functional during the Huygens descent. But, the direct MS analysis of the atmosphere, and the pyrolysis-MS analysis of aerosols allowed to make great discoveries which are still of primary importance to describe the Titan's lower atmosphere composition. This contribution aims at presenting this instrument that worked in the Titan's atmosphere, and summarizing the most important discoveries it allowed.

  8. Pyrolysis-gas chromatography/mass spectrometry analysis as a useful tool in forensic examination of automotive paint traces.

    PubMed

    Zieba-Palus, Janina; Zadora, Grzegorz; Milczarek, Jakub M; Kościelniak, Paweł

    2008-01-25

    Pyrolysis (Py)-GC/MS was applied in comparative analysis of polymer binder of 150 automobile clearcoat samples. It was found that binders of identical type and similar infrared spectra can be, in most cases, effectively differentiated, sometimes based only on the presence of peaks of very low intensity originating from minor paint components. The qualitative procedure of pyrograms comparison was developed. The results obtained, enable one to draw the conclusion that Py-GC/MS appears as valuable, very informative analytical technique of car paint samples examination. Providing identification of paint pyrolysis products, it enables discrimination of samples on the basis of their composition. However, in some cases, paint samples were still indistinguishable on the basis of their pyrograms.

  9. Incorporation of Gas Chromatography-Mass Spectrometry into the Undergraduate Organic Chemistry Laboratory Curriculum

    ERIC Educational Resources Information Center

    Giarikos, Dimitrios G.; Patel, Sagir; Lister, Andrew; Razeghifard, Reza

    2013-01-01

    Gas chromatography-mass spectrometry (GC-MS) is a powerful analytical tool for detection, identification, and quantification of many volatile organic compounds. However, many colleges and universities have not fully incorporated this technique into undergraduate teaching laboratories despite its wide application and ease of use in organic…

  10. DEVELOPMENTS IN DIRECT THERMAL EXTRACTION GAS CHROMATOGRAPHY-MASS SPECTROMETRY OF FINE AEROSOLS

    EPA Science Inventory

    This examines thermal extraction gas chromatography-mass spectrometry (TE/GC/MS) applied to aerosols collected on filters. Several different TE/GC/MS systems as a group have speciated hundreds of individual organic constituents in ambient fine aerosols. Molecular marker source ap...

  11. Incorporation of Gas Chromatography-Mass Spectrometry into the Undergraduate Organic Chemistry Laboratory Curriculum

    ERIC Educational Resources Information Center

    Giarikos, Dimitrios G.; Patel, Sagir; Lister, Andrew; Razeghifard, Reza

    2013-01-01

    Gas chromatography-mass spectrometry (GC-MS) is a powerful analytical tool for detection, identification, and quantification of many volatile organic compounds. However, many colleges and universities have not fully incorporated this technique into undergraduate teaching laboratories despite its wide application and ease of use in organic…

  12. Gas chromatography-mass spectrometry (GC-MS) analysis of extractives of naturally durable wood

    Treesearch

    G.T. Kirker; A.B. Blodgett; S.T. Lebow; C.A. Clausen

    2011-01-01

    A preliminary study to evaluate naturally durable wood species in an above ground field trial using Gas Chromatography-Mass Spectrometry (GC-MS) detected differences in fatty acid extractives between species and within the same species over time. Fatty acids were extracted with chloroform: methanol mixture then methylated with sodium methoxide and fractionated using...

  13. MICELLAR ELECTROKINETIC CHROMATOGRAPHY-MASS SPECTROMETRY (R823292)

    EPA Science Inventory

    The combination of micellar electrokinetic chromatography (MEKC) with mass spectrometry (MS) is very attractive for the direct identification of analyte molecules, for the possibility of selectivity enhancement, and for the structure confirmation and analysis in a MS-MS mode. The...

  14. MICELLAR ELECTROKINETIC CHROMATOGRAPHY-MASS SPECTROMETRY (R823292)

    EPA Science Inventory

    The combination of micellar electrokinetic chromatography (MEKC) with mass spectrometry (MS) is very attractive for the direct identification of analyte molecules, for the possibility of selectivity enhancement, and for the structure confirmation and analysis in a MS-MS mode. The...

  15. High-Performance Liquid Chromatography-Mass Spectrometry.

    ERIC Educational Resources Information Center

    Vestal, Marvin L.

    1984-01-01

    Reviews techniques for online coupling of high-performance liquid chromatography with mass spectrometry, emphasizing those suitable for application to nonvolatile samples. Also summarizes the present status, strengths, and weaknesses of various techniques and discusses potential applications of recently developed techniques for combined liquid…

  16. Applications of liquid chromatography-mass spectrometry for food analysis.

    PubMed

    Di Stefano, Vita; Avellone, Giuseppe; Bongiorno, David; Cunsolo, Vincenzo; Muccilli, Vera; Sforza, Stefano; Dossena, Arnaldo; Drahos, László; Vékey, Károly

    2012-10-12

    HPLC-MS applications in the agrifood sector are among the fastest developing fields in science and industry. The present tutorial mini-review briefly describes this analytical methodology: HPLC, UHPLC, nano-HPLC on one hand, mass spectrometry (MS) and tandem mass spectrometry (MS/MS) on the other hand. Analytical results are grouped together based on the type of chemicals analyzed (lipids, carbohydrates, glycoproteins, vitamins, flavonoids, mycotoxins, pesticides, allergens and food additives). Results are also shown for various types of food (ham, cheese, milk, cereals, olive oil and wines). Although it is not an exhaustive list, it illustrates the main current directions of applications. Finally, one of the most important features, the characterization of food quality (including problems of authentication and adulteration) is discussed, together with a future outlook on future directions. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Analysis of radioactive mixed hazardous waste using derivatization gas chromatography/mass spectrometry, liquid chromatography, and liquid chromatography/mass spectrometry

    SciTech Connect

    Campbell, J.A.; Lerner, B.D.; Bean, R.M.; Grant, K.E.; Lucke, R.B.; Mong, G.M.; Clauss, S.A.

    1994-08-01

    Six samples of core segments from Tank 101-SY were analyzed for chelators, chelator fragments, and several carboxylic acids by derivatization gas chromatography/mass spectrometry. The major components detected were ethylenediaminetetraacetic acid, nitroso-iminodiacetic acid, nitrilotriacetic acid, citric acid, succinic acid, and ethylenediaminetriacetic acid. The chelator of highest concentration was ethylenediaminetetraacetic acid in all six samples analyzed. Liquid chromatography was used to quantitate low molecular weight acids including oxalic, formic, glycolic, and acetic acids, which are present in the waste as acid salts. From 23 to 61% of the total organic carbon in the samples analyzed was accounted for by these acids.

  18. Structural analysis of commercial ceramides by gas chromatography-mass spectrometry.

    PubMed

    Bleton, J; Gaudin, K; Chaminade, P; Goursaud, S; Baillet, A; Tchapla, A

    2001-05-11

    A simple method using gas chromatography-mass spectrometry was applied to analyse structures of ceramides. Identification of trimethylsilylated ceramides were obtained in short analysis times (derivatization of ceramides in 30 min at room temperature and 20 min gas chromatography mass spectrometry run) even for complex mixtures. For example in ceramide Type III, 18 peaks were observed which represent 27 various structures. The coeluted compounds were ceramides containing the same functional groups and the same carbon number but with a different distribution on the two alkyl chains of the molecule. They were accurately differentiated by mass spectrometry. Therefore, 83 structures of trimethylsilylated ceramides were identified in 11 different commercial mixtures. For 52 structures of these, mass spectral data were not described in the literature, neither full mass spectra nor characteristic fragments.

  19. Characterization and Differentiation of Geometric Isomers of 3-methylfentanyl Analogs by Gas Chromatography/Mass Spectrometry, Liquid Chromatography/Mass Spectrometry, and Nuclear Magnetic Resonance Spectroscopy.

    PubMed

    Kanamori, Tatsuyuki; Iwata, Yuko T; Segawa, Hiroki; Yamamuro, Tadashi; Kuwayama, Kenji; Tsujikawa, Kenji; Inoue, Hiroyuki

    2017-06-26

    The cis and trans isomers of 3-methylfentanyl and its three analogs were chemically synthesized, and these compounds were characterized and differentiated by gas chromatography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS), and nuclear magnetic resonance (NMR) spectroscopy. The cis and trans isomers of the 3-methylfentanyl analogs were completely separated by GC/MS. Although the high temperature of the GC injection port caused thermal degradation of β-hydroxy-3-methylfentanyl, the degradation was completely suppressed by trimethylsilyl derivatization. The isomers were also well separated by LC/MS on an octadecylsilyl column with 10 mM ammonium acetate and methanol as the mobile phase. The proton NMR signals were split when the hydrochloride salts of the 3-methylfentanyl analogs were dissolved in deuterated chloroform because stereoisomers were formed by the coordination of the hydrochloride proton to the nitrogen of the piperidine ring of the 3-methylfentanyl analogs. © 2017 American Academy of Forensic Sciences.

  20. Emerging liquid chromatography-mass spectrometry technologies improving dried blood spot analysis.

    PubMed

    Rao, Ramisetti Nageswara

    2014-08-01

    Dried blood spots (DBS), a micro blood sampling technique, has recently gained interest in drug discovery and development due to its inherent advantages over the conventional whole blood, plasma or serum sample collection. Since the regulatory authorities have agreed to the use of blood as an acceptable biological matrix for drug exposure measurements, its applications have been extended not only to therapeutic drug monitoring but also to toxicokinetic and pharmacokinetic studies. The pharmaceutical industry is keen to promote DBS as a prominent tool in bioanalytical applications due to the financial, ethical and organizational issues involved in clinical trials. This could be accomplished due to the latest advances in modern analytical technology, particularly liquid chromatography-mass spectrometry. The present review discusses some of the emerging liquid chromatography-mass spectrometry technologies in improving DBS analysis for its innovative applications in the development of new drugs.

  1. Determination of sucrose in equine serum using liquid chromatography-mass spectrometry (LC/MS).

    PubMed

    D'Arcy-Moskwa, E; Weston, L; Noble, G N; Raidal, S L

    2011-11-15

    Mucosal integrity may be objectively assessed by determination of the absorption of exogenous substances such as sucrose. Gas chromatography-mass spectrometry (GC/MS) and liquid chromatography-mass spectrometry (LC/MS) have been reported for the accurate quantification of low concentrations of sucrose in serum. LC/MS offered the advantage of high sensitivity and mass selectivity without the need for extensive sample derivatization required for GC/MS methods. However, the high polarity and non-volatile nature of the sucrose molecule renders LC/MS techniques challenging. Previously published reports lacked sufficient detail to permit replication of methodology. Problems encountered with existing protocols included poor peak resolution and weak fragmentation of the parent molecule. This communication describes a LC/MS protocol developed to provide improved resolution and product detection.

  2. Global urinary metabolic profiling procedures using gas chromatography-mass spectrometry.

    PubMed

    Chan, Eric Chun Yong; Pasikanti, Kishore Kumar; Nicholson, Jeremy K

    2011-09-08

    The role of urinary metabolic profiling in systems biology research is expanding. This is because of the use of this technology for clinical diagnostic and mechanistic studies and for the development of new personalized health care and molecular epidemiology (population) studies. The methodologies commonly used for metabolic profiling are NMR spectroscopy, liquid chromatography mass spectrometry (LC/MS) and gas chromatography-mass spectrometry (GC/MS). In this protocol, we describe urine collection and storage, GC/MS and data preprocessing methods, chemometric data analysis and urinary marker metabolite identification. Results obtained using GC/MS are complementary to NMR and LC/MS. Sample preparation for GC/MS analysis involves the depletion of urea via treatment with urease, protein precipitation with methanol, and trimethylsilyl derivatization. The protocol described here facilitates the metabolic profiling of ∼400-600 metabolites in 120 urine samples per week.

  3. Applications of liquid chromatography--mass spectrometry in analytical toxicology: a review.

    PubMed

    Hoja, H; Marquet, P; Verneuil, B; Lotfi, H; Pénicaut, B; Lachâtre, G

    1997-01-01

    Liquid chromatography-mass spectrometry (LC-MS), after long-term development that has introduced seven major interfacing techniques, is finally suitable for application in the field of analytical toxicology. Various compound classes can be analyzed, and sensitivities for more or less polar analytes that are as good as or better than those of gas chromatography-mass spectrometry can be obtained with modern interfaces. In addition, because ionization is often softer than classical electron impact, some LC-MS interfaces are able to handle fragile species that are otherwise not amenable to MS. This review is intended to present LC-MS to less familiarized readers and to give an extensive overview of the application of the different coupling techniques to doping agents, drugs of abuse, forensic analysis, toxic compounds of various nature, and several toxicologically relevant therapeutic drugs. Experimental parameters such as the interfaces used, ionization methods, detection limits, and experimental details for exemplary applications are given.

  4. Application of Headspace Solid Phase Microextraction and Gas Chromatography/Mass Spectrometry for Rapid Detection of the Chemical Warfare Agent Sulfur Mustard

    DTIC Science & Technology

    2002-05-16

    Title of Thesis: “Application of Headspace Solid Phase Microextraction and Gas Chromatography/Mass Spectrometry for Rapid...TITLE AND SUBTITLE Application of Headspace Solid Phase Microextraction and Gas Chromatography/Mass Spectrometry for Rapid Detection of the Chemical...phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS). Five commercially available SPME fibers were investigated to determine the

  5. The bridge between thin layer chromatography-mass spectrometry and high-performance liquid chromatography-mass spectrometry: The realization of liquid thin layer chromatography-mass spectrometry (LTLC-MS).

    PubMed

    Li, Yafeng; Wang, Jianing; Zhan, Lingpeng; Wleklinski, Michael; Wang, Jiyun; Xiong, Caiqiao; Liu, Huihui; Zhou, Yueming; Nie, Zongxiu

    2016-08-19

    The combination of thin layer chromatography (TLC) and mass spectrometry (MS) has been studied for decades, but for most cases MS detection is done after TLC separation is finished. Here, an online simultaneous TLC-MS analysis system, liquid thin layer chromatography-mass spectrometry (LTLC-MS), is developed which successfully synchronize TLC separation process and MS detection process like GC-MS and HPLC-MS do. And there's no need to use specially designed TLC, just regular TLC plates are enough. LTLC-MS method is composed of a newly developed ambient ionization method, glow discharge-matrix assisted infrared desorption ionization (GD-MAIRDI), and forced-flow TLC (FFTLC) technique, which guarantees the MS detection process does not disturb the TLC separation process throughout the whole analysis. The whole LTLC-MS analysis only need two steps and less than 15min. Mixtures as well as the two main components of a pain relief pills have been successfully analyzed by LTLC-MS. This proof of concept study opens up new possibilities of combining TLC with MS, and will further broaden the application abilities of TLC. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Metabonomics investigation of human urine after ingestion of green tea with gas chromatography/mass spectrometry, liquid chromatography/mass spectrometry and (1)H NMR spectroscopy.

    PubMed

    Law, Wai Siang; Huang, Pei Yun; Ong, Eng Shi; Ong, Choon Nam; Li, Sam Fong Yau; Pasikanti, Kishore Kumar; Chan, Eric Chun Yong

    2008-08-01

    A method using gas chromatography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS) and (1)H NMR with pattern recognition tools such as principle components analysis (PCA) was used to study the human urinary metabolic profiles after the intake of green tea. From the normalized peak areas obtained from GC/MS and LC/MS and peak heights from (1)H NMR, statistical analyses were used in the identification of potential biomarkers. Metabolic profiling by GC/MS provided a different set of quantitative signatures of metabolites that can be used to characterize the molecular changes in human urine samples. A comparison of normalized metabonomics data for selected metabolites in human urine samples in the presence of potential overlapping peaks after tea ingestion from LC/MS and (1)H NMR showed the reliability of the current approach and method of normalization. The close agreements of LC/MS with (1)H NMR data showed that the effects of ion suppression in LC/MS for early eluting metabolites were not significant. Concurrently, the specificity of detecting the stated metabolites by (1)H NMR and LC/MS was demonstrated. Our data showed that a number of metabolites involved in glucose metabolism, citric acid cycle and amino acid metabolism were affected immediately after the intake of green tea. The proposed approach provided a more comprehensive picture of the metabolic changes after intake of green tea in human urine. The multiple analytical approach together with pattern recognition tools is a useful platform to study metabolic profiles after ingestion of botanicals and medicinal plants.

  7. Simultaneous Determination of Cyanide and Thiocyanate in Plasma by Chemical Ionization Gas Chromatography Mass-Spectrometry (CI-GC-MS)

    DTIC Science & Technology

    2012-09-04

    ORIGINAL PAPER Simultaneous determination of cyanide and thiocyanate in plasma by chemical ionization gas chromatography mass-spectrometry (CI-GC-MS...chemical ioniza- tion gas chromatography-mass spectrometry was developed for the simultaneous determination of cyanide and thiocya- nate in plasma...Sample preparation for this analysis required essentially one-step by combining the reaction of cyanide and thiocyanate with pentafluorobenzyl bromide

  8. Discrimination of bacteria using pyrolysis-gas chromatography-differential mobility spectrometry (Py-GC-DMS) and chemometrics.

    PubMed

    Cheung, William; Xu, Yu; Thomas, C L Paul; Goodacre, Royston

    2009-03-01

    Discrimination of bacteria was investigated using pyrolysis-gas chromatography-differential mobility spectrometry (Py-GC-DMS). Three strains belonging to the genus Bacillus were investigated and these included two strains of Bacillus subtilis and a single Bacillus megaterium. These were chosen so as to evaluate the possibility of bacterial strain discrimination using Py-GC-DMS. The instrument was constructed in-house and the long-term reproducibility of the instrument was evaluated over a period of 60 days using a Scotch whisky quality control. To assess the reproducibility further each bacterium was cultured six times and each culture was analysed in replicate to give three analytical replicates. The DMS data were generated in both positive and negative modes, and the data in each mode were analysed independently of each other. The Py-GC-DMS data were pre-processed via correlation optimised warping (COW) and asymmetric least square (ALS) to align the DMS chromatograms and to remove any unavoidable baseline shifts, prior to normalisation. Processed chromatograms were analysed using principal component analysis (PCA) followed by supervised learning methodology using partial least squares for discriminant analysis (PLS-DA). It was found that the separations between B. subtilis and B. megaterium can be readily observed by PCA; however, strain discrimination within the two B. subtilis was only possible using supervised learning. As multiple biological replicates were analysed an exhaustive splitting of the training and test sets was undertaken and this allowed correct classification rates (CCRs) to be assessed for the 3375 test sets. It was found that with PLS-DA the negative ion mode DMS data were more discriminatory than the positive mode data.

  9. Study on the photostability of guaiazulene by high-performance liquid chromatography/mass spectrometry and gas chromatography/mass spectrometry.

    PubMed

    Fiori, Jessica; Gotti, Roberto; Albini, Angelo; Cavrini, Vanni

    2008-09-01

    The photostability of guaiazulene (1,4-dimethyl-7-isopropylazulene; GA), a natural azulenic compound used in cosmetic and health-care products, as well as in pharmaceutical preparations, was investigated in solution (methanol, ethanol, acetonitrile), by different techniques: gas chromatography/mass spectrometry (GC/MS) and high-performance liquid chromatography combined with atmospheric pressure chemical ionization mass spectrometry and UV detection (LC/APCI-MS and HPLC/UV). A solar simulator (xenon-arc lamp) was used as UV-A radiation source. The study involved: monitoring compound decomposition, identifying products of photodegradation (PPs), assessing the role of oxygen and evaluating the kinetics of the process. Minor PPs are volatile compounds and were characterized by GC/MS, while oligomeric polyoxygenated compounds, tentatively characterized on the basis of MS and MS/MS spectra, were found to be the main photoproducts. The photodegradation was found to be enhanced by the presence of oxygen; nevertheless, determination of the singlet oxygen quantum yield for GA gave a lower value than that for the reference standard Rose Bengal. The obtained results and the developed stability-indicating methods (GC/MS and LC/MS) are of interest for stability studies and/or quality control purposes of GA as raw material or cosmetic products.

  10. Determination of hormonal growth promoters in bovine hair: comparison of liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry methods for estradiol benzoate and nortestosterone decanoate.

    PubMed

    Duffy, Eleanor; Rambaud, Lauriane; Le Bizec, Bruno; O'Keeffe, Michael

    2009-04-01

    The detection of steroid residues in hair is a powerful strategy to demonstrate long-term administration of these growth promoters in meat production animals. Analysis of the ester form of administered steroids is an unambiguous approach to prove the illegal use of natural hormones. For detection, gas chromatography-mass spectrometry (GC-MS/MS) was generally used. However, recent advances in liquid chromatography-tandem mass spectrometry (LC-MS/MS) technology have improved the robustness and potential sensitivity of this method. This paper describes development and validation, according to Commission Decision 2002/657/EC, of LC-MS/MS and GC-MS/MS methods, in two separate laboratories, for determination of steroid esters in bovine hair. Bovine hair samples taken from animals treated with estradiol-3-benzoate and nortestosterone decanoate, as well as from an untreated animal, were used to evaluate the comparability of the results of the two validated methods. The results of the inter-comparison demonstrate that both the LC-MS/MS and the GC-MS/MS methods are fit for purpose and capable of determining steroid esters in hair samples from treated bovine animals.

  11. Gas chromatography/mass spectrometry analysis of exhaled leukotrienes in asthmatic patients

    PubMed Central

    Cap, P; Chladek, J; Pehal, F; Maly, M; Petru, V; Barnes, P; Montuschi, P

    2004-01-01

    Background: Leukotriene-like immunoreactivity has been detected in exhaled breath condensate (EBC), but definitive evidence for the presence of leukotrienes (LTs) in this biological fluid is not available. A study was undertaken to determine whether LTC4, LTD4, LTE4, and LTB4 are measurable in EBC by gas chromatography/mass spectrometry and to quantify exhaled LTs in adults and children with asthma and in control subjects. Methods: Twenty eight adults and 33 children with mild to moderate persistent asthma treated with inhaled corticosteroids and age matched healthy controls (50 adults and 50 children) were studied. LTB4, LTC4, LTD4, and LTE4 in EBC were measured by gas chromatography/mass spectrometry. Results: LTD4, LTE4, and LTB4 were detectable in all samples. Concentrations of LTC4 in EBC were either close to or below the detection limit of 1 pg/ml. Median exhaled LTD4, LTE4, and LTB4 concentrations in asthmatic adults were increased 4.1-fold (p<0.001), 1.8-fold (p<0.01), and 2.6-fold (p<0.001), respectively, compared with values in healthy adults. Median exhaled LTD4, LTE4, and LTB4 concentrations in asthmatic children were increased 2.8-fold (p<0.001), 1.3-fold (p<0.001), and 1.6-fold (p<0.001), respectively, compared with those in healthy children. In patients with asthma there was a correlation between exhaled LTD4 and LTE4 in both adults (r = 0.87, p<0.0001) and children (r = 0.78, p<0.0001). Conclusions: Gas chromatography/mass spectrometry can be used to accurately quantify exhaled LTs which are increased in asthmatic adults and children compared with controls. PMID:15170025

  12. Screening of Brazilian fruit aromas using solid-phase microextraction-gas chromatography-mass spectrometry.

    PubMed

    Augusto, F; Valente, A L; dos Santos Tada, E; Rivellino, S R

    2000-03-17

    Manual headspace solid-phase microextraction (SPME) coupled to gas chromatography-mass spectrometry (GC-MS) was used for the qualitative analysis of the aromas of four native Brazilian fruits: cupuassu (Theobroma grandiflorum, Spreng.), cajá (Spondias lutea. L.), siriguela (Spondias purpurea, L.) and graviola (Anona reticulata, L). Industrialized pulps of these fruits were used as samples, and extractions with SPME fibers coated with polydimethylsiloxane, polyacrylate, Carbowax and Carboxen were carried out. The analytes identified included several alcohols, esters, carbonyl compounds and terpernoids. The highest amounts extracted, evaluated from the sum of peak areas, were achieved using the Carboxen fiber.

  13. Analysis of the citric acid cycle intermediates using gas chromatography-mass spectrometry.

    PubMed

    Kombu, Rajan S; Brunengraber, Henri; Puchowicz, Michelle A

    2011-01-01

    Researchers view analysis of the citric acid cycle (CAC) intermediates as a metabolomic approach to identifying unexpected correlations between apparently related and unrelated pathways of metabolism. Relationships of the CAC intermediates, as measured by their concentrations and relative ratios, offer useful information to understanding interrelationships between the CAC and metabolic pathways under various physiological and pathological conditions. This chapter presents a relatively simple method that is sensitive for simultaneously measuring concentrations of CAC intermediates (relative and absolute) and other related intermediates of energy metabolism using gas chromatography-mass spectrometry.

  14. Analysis of the anthraquinones aloe-emodin and aloin by gas chromatography/mass spectrometry.

    PubMed

    ElSohly, Mahmoud A; Gul, Waseem; Murphy, Timothy P

    2004-12-20

    A procedure was developed for the determination of low levels of the anthraquinones aloe-emodin and aloin A (barbalin) in aloe products based on gas chromatography/mass spectrometry (GC/MS) of the trimethyl silyl (TMS) derivatives of these analytes in the presence of Chrysophanol used as internal standard. The method was used to analyze several aloe based commercial products (liquids, gels and solids). Wide variation in the level of these anthraquinones was observed among the different products. The method had a sensitivity of 0.005 ppm of aloe-emodin and 0.05 ppm of aloin.

  15. Gas chromatography/mass spectrometry characterization of historical varnishes of ancient Italian lutes and violin.

    PubMed

    Echard, J P; Benoit, C; Peris-Vicente, J; Malecki, V; Gimeno-Adelantado, J V; Vaiedelich, S

    2007-02-12

    The organic constituents of historical vanishes from two ancient Italian lutes and a Stradivari violin, kept in the Musée de la musique in Paris, have been characterized using gas chromatography-mass spectrometry. Results have been compared with the chromatograms and mass spectra of recent as well as old naturally aged reference materials. The three historical varnishes analyzed have been shown to be oil varnishes, probably mixtures of linseed oil with resins. Identification of diterpenoids and triterpenoids compounds, and of the resins that may have been ingredients of the varnishes, are discussed in this paper.

  16. Identification of cryptorchidism in horses by analysing urine samples with gas chromatography/mass spectrometry.

    PubMed

    Leung, David K K; Tang, Francis P W; Wan, Terence S M; Wong, Jenny K Y

    2011-01-01

    Currently there are two common radioimmunoassay-based methods for the detection of equine cryptorchidism; one measures testosterone concentrations in peripheral blood samples taken before and after an intravenous injection of human chorionic gonadotrophin (hCG) and the other measures plasma estrone sulfate. However, each of these invasive methods has its own shortfalls and neither gives unequivocal results. In this article a highly reliable gas chromatography/mass spectrometry (GC/MS) method is described based on the analysis of urine samples for the identification of cryptorchidism in horses, some as young as 2 years old. 2009 Elsevier Ltd. All rights reserved.

  17. Analysis of corticosteroids in equine urine by liquid chromatography-mass spectrometry.

    PubMed

    Tang, P W; Law, W C; Wan, T S

    2001-04-15

    A liquid chromatography-mass spectrometry (LC-MS) method for the analysis of corticosteroids in equine urine was developed. Corticosteroid conjugates were hydrolysed with beta-glucuronidase; free and enzyme-released corticosteroids were then extracted from the samples with ethyl acetate followed by a base wash. The isolated corticosteroids were detected by LC-MS and confirmed by LC-MS-MS in the positive atmospheric pressure chemical ionisation mode. Twenty-three corticosteroids (comprising hydrocortisone, deoxycorticosterone and 21 synthetic corticosteroids), each at 5 ng/ml in urine, could easily be analysed in 10 min.

  18. Heparin stability by determining unsubstituted amino groups using hydrophilic interaction chromatography mass spectrometry.

    PubMed

    Fu, Li; Li, Lingyun; Cai, Chao; Li, Guoyun; Zhang, Fuming; Linhardt, Robert J

    2014-09-15

    The thermal instability of the anticoagulant heparin is associated, in part, with the solvolytic loss of N-sulfo groups. This study describes a new method to assess the increased content of unsubstituted amino groups present in thermally stressed and autoclave-sterilized heparin formulations. N-Acetylation of heparin samples with acetic anhydride-d6 is followed by exhaustive heparinase treatment and disaccharide analysis by hydrophilic interaction chromatography mass spectrometry (HILIC-MS). The introduction of a stable isotopic label provides a sensitive probe for the detection and localization of the lost N-sulfo groups, potentially providing valuable insights into the degradation mechanism and the reasons for anticoagulant potency loss.

  19. Applications of liquid chromatography-mass spectrometry in metabolic studies of explosives.

    PubMed

    Yinon, J; Hwang, D G

    1987-05-08

    Liquid chromatography-mass spectrometry was used for the detection and identification of metabolites of 2,4,6-trinitrotoluene (TNT) in urine and blood. The metabolites were found in the urine of rats and in the blood of rabbits fed with TNT, in the urine of rats exposed to TNT by skin absorption and in the urine of TNT munition workers. The detected metabolites, formed by reduction processes, included 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, 2,4-diamino-6-nitrotoluene and 2,6-diamino-4-nitrotoluene, in addition to untransformed TNT.

  20. Analysis of volatile organic compounds in groundwater samples by gas chromatography-mass spectrometry

    SciTech Connect

    Bernhardt, J.

    1995-08-23

    The Savannah River Site contains approximately 1500 monitoring wells from which groundwater samples are collected. Many of these samples are sent off-site for various analyses, including the determination of trace volatile organic compounds (VOCs). This report describes accomplishments that have been made during the past year which will ultimately allow VOC analysis to be performed on-site using gas chromatography-mass spectrometry. Through the use of the on-site approach, it is expected that there will be a substantial cost savings. This approach will also provide split-sample analysis capability which can serve as a quality control measure for off-site analysis.

  1. Comparison of photoacoustic radiometry to gas chromatography/mass spectrometry methods for monitoring chlorinated hydrocarbons

    SciTech Connect

    Sollid, J.E.; Trujillo, V.L.; Limback, S.P.; Woloshun, K.A.

    1996-03-01

    A comparison of two methods of gas chromatography mass spectrometry (GCMS) and a nondispersive infrared technique, photoacoustic radiometry (PAR), is presented in the context of field monitoring a disposal site. First is presented an historical account describing the site and early monitoring to provide an overview. The intent and nature of the monitoring program changed when it was proposed to expand the Radiological Waste Site close to the Hazardous Waste Site. Both the sampling methods and analysis techniques were refined in the course of this exercise.

  2. Clinical Proteomics: Liquid Chromatography-Mass Spectrometry (LC-MS) Purification Systems.

    PubMed

    Henry, Michael; Meleady, Paula

    2017-01-01

    Liquid chromatography-mass spectrometry (LC-MS) has become a routine powerful technology in clinical proteomic studies for protein identification, protein characterization and the discovery of biomarkers. In this chapter, we describe two protocol methods to analyze clinical patient samples using a resin based depletion column followed by either protein In-gel enzymatic digestion or protein in-solution enzymatic digestion and then analysis by one-dimensional reverse-phase chromatography or two-dimensional strong cation exchange (SCX)-reverse-phase chromatography (RPC).

  3. High sensitivity measurement of amino acid isotope enrichment using liquid chromatography-mass spectrometry.

    PubMed

    van Eijk, Hans M H; Wijnands, Karolina A P; Bessems, Babs A F M; Olde Damink, Steven W; Dejong, Cornelis H C; Poeze, Martijn

    2012-09-15

    Measurement of the incorporation or conversion of infused stable isotope enriched metabolites in vivo such as amino acids plays a key role in metabolic research. Specific routes are frequently probed in knockout mouse models limiting the available amount of sample. Although less precise as compared to combustion-isotope ratio mass spectrometry (C-IRMS), gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-mass spectrometry (LC-MS) techniques are therefore often the method of choice to measure isotopic enrichment of target metabolites. However, under conditions of metabolic depletion, the precision of these systems becomes limiting. In this paper, studies were performed to enhance the sensitivity and precision of isotope enrichment measurements using LC-MS. Ion-statistics and resolution were identified as critical factors for this application when using a linear trap mass spectrometer. The combination with an automated pre-column derivatization and a carefully selected solvent mix allowed us to measure isotopic enrichments down to 0.005% at plasma concentrations as low as 5 μmol/l, an improvement by a factor of 100 compared to alternative methods. The resulting method now allowed measurement of the in vivo conversion of the amino acid arginine into citrulline as a marker for the production of nitric oxide in an in vivo murine endotoxemia model with depleted plasma levels of arginine and citrulline.

  4. Serotonin metabolism in rat skin: characterization by liquid chromatography-mass spectrometry.

    PubMed

    Semak, Igor; Korik, Elena; Naumova, Marya; Wortsman, Jacobo; Slominski, Andrzej

    2004-01-01

    We have recently uncovered the full expression of novel cutaneous serotoninergic and melatoninergic systems in the human and hamster skin. In this work, we have characterized serotonin metabolism in the rat skin using liquid chromatography-mass spectrometry and found that serotonin undergoes acetylation in the presence of acetyl coenzyme A. Inhibition of serotonin acetylation with Cole bisubstrate inhibitor shows that rat skin expresses both arylalkylamine and arylamine N-acetyltransferase activities. The serotonin degradation product-5-hydroxyindole acetic acid is also detected and pargyline (monoaminooxidase inhibitor) suppresses almost completely 5-hydroxyindole acetic acid accumulation. Together with previous data, the present study clearly demonstrates that biotransformation of serotonin in mammalian skin follows two alternate pathways. In the first pathway, serotonin is acetylated by arylalkylamine and arylamine N-acetyltransferases to generate the precursor of melatonin. Alternately, serotonin may undergo oxidative deamination by monoaminooxidase followed by enzymatic degradation by aldehyde dehydrogenase into 5-hydroxyindole acetic acid, which is presumably devoid of biological activity. Thus, the current methodological development of a liquid chromatography-mass spectrometry-based assay allows rapid resolution of the cutaneous metabolism of serotonin.

  5. Metabolomics by Gas Chromatography-Mass Spectrometry: Combined Targeted and Untargeted Profiling.

    PubMed

    Fiehn, Oliver

    2016-04-01

    Gas chromatography-mass spectrometry (GC-MS)-based metabolomics is ideal for identifying and quantitating small-molecule metabolites (<650 Da), including small acids, alcohols, hydroxyl acids, amino acids, sugars, fatty acids, sterols, catecholamines, drugs, and toxins, often using chemical derivatization to make these compounds sufficiently volatile for gas chromatography. This unit shows how GC-MS-based metabolomics allows integration of targeted assays for absolute quantification of specific metabolites with untargeted metabolomics to discover novel compounds. Complemented by database annotations using large spectral libraries and validated standard operating procedures, GC-MS can identify and semiquantify over 200 compounds from human body fluids (e.g., plasma, urine, or stool) per study. Deconvolution software enables detection of more than 300 additional unidentified signals that can be annotated through accurate mass instruments with appropriate data processing workflows, similar to untargeted profiling using liquid chromatography-mass spectrometry. GC-MS is a mature technology that uses not only classic detectors (quadrupole) but also target mass spectrometers (triple quadrupole) and accurate mass instruments (quadrupole-time of flight). This unit covers sample preparation from mammalian samples, data acquisition, quality control, and data processing. Copyright © 2016 John Wiley & Sons, Inc.

  6. Gas-liquid chromatography-mass spectrometry of synthetic ceramides containing phytosphingosine.

    PubMed

    Hammarström, S

    1970-05-01

    Ceramides containing phytosphingosine as base and one of the fatty acids 16:0, 18:0, 20:0, 22:0, 23:0, and 24:0, were prepared by direct coupling in the presence of a mixed carbodiimide. The ceramides were analyzed as the 1,3,4-tri-O-trimethylsilyl ether derivatives by gas-liquid chromatography-mass spectrometry. Gas chromatographic data is presented, and structures of mass spectral ions are suggested. The structures are supported by mass spectra of the homologous ceramides, by deuterium-labeling experiments, and by high resolution mass spectrometry. Some ions, formed by cleavage between C-3 and C-4 in the long-chain base, indicate the phytosphingosine nature of the ceramide.

  7. On-line electrochemistry/liquid chromatography/mass spectrometry for the simulation of pesticide metabolism.

    PubMed

    Lohmann, Wiebke; Dötzer, Reinhard; Gütter, Gerald; Van Leeuwen, Suze M; Karst, Uwe

    2009-01-01

    On-line electrochemistry/liquid chromatography/mass spectrometry (EC/LC/MS) was employed to mimic the oxidative metabolism of the fungicide boscalid. High-resolution mass spectrometry and MS/MS experiments were used to identify its electrochemical oxidation products. Furthermore, the introduction of a second electrochemical cell with reductive conditions provided important additional information on the oxidation products. With this equipment, hydroxylation, dehydrogenation, formation of a covalent ammonia adduct, and dimerization were detected after initial one-electron oxidation of boscalid to a radical cation. On-line reaction with glutathione yielded different isomeric covalent glutathione adducts. The results of the electrochemical oxidation are in good accordance with previously reported in vivo experiments, showing that EC/LC/MS is a useful tool for studying biotransformation reactions of various groups of xenobiotics.

  8. Atmospheric pressure chemical ionisation liquid chromatography/mass spectrometry of bacteriochlorophylls from Chlorobiaceae: characteristic fragmentations.

    PubMed

    Airs, Ruth L; Keely, Brendan J

    2002-01-01

    Atmospheric pressure chemical ionisation liquid chromatography/mass spectrometry/mass spectrometry (APCI-LC/MS/MS) has been applied to the study of bacteriochlorophylls c, d, and e of phototrophic prokaryotes. Cultures of Chlorobiaceae containing bacteriochlorophyll c, d or e were examined using a high-resolution high-performance liquid chromatography (HPLC) method and APCI-LC/MS/MS employing post-column addition of formic acid. The results reveal complex distributions of bacteriochlorophyll homologues, with some closely eluting species giving isobaric protonated molecules. On-line LC/MS/MS studies reveal characteristic fragment ions for bacteriochlorophylls c, d, and e. Fragmentations involving loss of the extended alkyl substituents that are unique to bacteriochlorophylls c, d and e and their derivatives have been rationalised by studying the phaeophorbides and the results applied to the direct study of the bacteriochlorophylls.

  9. Analysis of estrogens and androgens in postmenopausal serum and plasma by liquid chromatography-mass spectrometry.

    PubMed

    Wang, Qingqing; Bottalico, Lisa; Mesaros, Clementina; Blair, Ian A

    2015-07-01

    Liquid chromatography-selected reaction monitoring/mass spectrometry-based methodology has evolved to the point where accurate analyses of trace levels of estrogens and androgens in postmenopausal serum and plasma can be accomplished with high precision and accuracy. A suite of derivatization procedures has been developed, which together with modern mass spectrometry instrumentation provide investigators with robust and sensitive methodology. Pre-ionized derivatives are proving to be useful as they are not subject to suppression of the electrospray signal. Postmenopausal women with elevated plasma or serum estrogens are thought to be at increased risk for breast and endometrial cancer. Therefore, significant advances in risk assessment should be possible now that reliable methodology is available. It is also possible to conduct analyses of multiple estrogens in plasma or serum. Laboratories that are currently employing liquid chromatography/mass spectrometry methodology can now readily implement this strategy. This will help conserve important plasma and serum samples available in Biobanks, as it will be possible to conduct high sensitivity analyses using low initial sample volumes. Reported levels of both conjugated and non-conjugated estrogen metabolites are close to the limits of sensitivity of many assays to date, urging caution in the interpretation of these low values. The analysis of serum androgen precursors in postmenopausal women has not been conducted routinely in the past using liquid chromatography/mass spectrometry methodology. Integration of serum androgen levels into the panel of metabolites analyzed could provide additional information for assessing cancer risk and should be included in the future.

  10. Identification of Unknown Contaminants in Water Samples from ISS Employing Liquid Chromatography/Mass Spectrometry/Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Rutz, Jeffrey A.; Schultz, John R.

    2008-01-01

    Mass Spectrometry/Mass Spectrometry (MS/MS) is a powerful technique for identifying unknown organic compounds. For non-volatile or thermally unstable unknowns dissolved in liquids, liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS) is often the variety of MS/MS used for the identification. One type of LC/MS/MS that is rapidly becoming popular is time-of-flight (TOF) mass spectrometry. This technique is now in use at the Johnson Space Center for identification of unknown nonvolatile organics in water samples from the space program. An example of the successful identification of one unknown is reviewed in detail in this paper. The advantages of time-of-flight instrumentation are demonstrated through this example as well as the strategy employed in using time-of-flight data to identify unknowns.

  11. Analysis of the venom of the Sydney funnel-web spider, Atrax robustus using gas chromatography mass spectrometry.

    PubMed

    Duffield, P H; Duffield, A M; Carroll, P R; Morgans, D

    1979-03-01

    Thirteen compounds have been identified using gas chromatography mass spectrometry in the venom of the Sydney funnel-web spider, Atrax robustus. The compounds were identified as their trimethylsilyl or pentafluoropropionate derivatives and were citric acid, lactic acid, phosphoric acid, glycerol, urea, glucose, gamma-aminobutyric acid, glycine, spermidine, spermine, tyramine and octopamine. Female venom contained trace quantities of 5-methyoxytryptamine which was not detected in male venom. Quantitative determination of tyramine and octopamine was achieved using chemical ionization (CH4) gas chromatography mass spectrometry and deuterated internal standards.

  12. Simultaneous determination of steviol and steviol glycosides by liquid chromatography-mass spectrometry.

    PubMed

    Shah, Romina; De Jager, Lowri S; Begley, Timothy H

    2012-01-01

    A direct, versatile method for the determination of steviol and nine steviol glycosides in food products has been developed by using electrospray ionisation liquid chromatography-mass spectrometry in the negative-ion mode. Ten stevia compounds were readily separated on an amino column by using a gradient separation. Data for analyte quantification were collected in the selected ion monitoring mode, giving the method limit of detection of 0.01-0.34 µg g⁻¹ and repeatability at the limit of quantitation of 2%-15% relative standard deviation. Thirty-four commercially available food products were tested by using the optimised method, and in these products rebaudioside A and stevioside comprised 52%-100% of the total steviol glycosides. Multiple reaction monitoring data were collected to provide analyte confirmation. Stability data for rebaudioside A stored at room temperature, 40°C and 60°C over a period of 1-14 days are shown.

  13. Rapid quantification of dimethyl methylphosphonate from activated carbon particles by static headspace gas chromatography mass spectrometry.

    PubMed

    Mitchell, Brendan L; Billingsley, Brit G; Logue, Brian A

    2013-06-07

    Activated carbon (AC) particles are utilized as an adsorbent for binding hazardous vapors in protective equipment. The binding affinity and utilization of these AC particles should be known to ensure effective and efficient use. Therefore, a simple and effective method was developed for the quantification of the chemical warfare agent simulant, dimethyl methylphosphonate (DMMP), from AC particles. Static headspace gas chromatography mass-spectrometry with internal standard, DMMP-d6, was used to perform the analysis. The method produced a linear dynamic range of 2.48-620g DMMP/kg carbon and a detection limit of 1.24g DMMP/kg carbon. Furthermore, the method produced a coefficient of variation of less than 16% for all intra- and inter-assay analyses. The method provided a simple and effective procedure for quantifying DMMP from AC particles and was applied to the analysis of a DMMP-exposed AC protective respirator filter.

  14. Current practice of liquid chromatography-mass spectrometry in metabolomics and metabonomics.

    PubMed

    Gika, Helen G; Theodoridis, Georgios A; Plumb, Robert S; Wilson, Ian D

    2014-01-01

    Based on publication and citation numbers liquid chromatography (LC-MS) has become the major analytical technology in the field of global metabolite profiling. This dominance reflects significant investments from both the research community and instrument manufacturers. Here an overview of the approaches taken for LC-MS-based metabolomics research is given, describing critical steps in the realisation of such studies: study design and its needs, specific technological problems to be addressed and major obstacles in data treatment and biomarker identification. The current state of the art for LC-MS-based analysis in metabonomics/metabolomics is described including recent developments in liquid chromatography, mass spectrometry and data treatment as these are applied in metabolomics underlining the challenges, limitations and prospects for metabolomics research. Examples of the application of metabolite profiling in the life sciences focusing on disease biomarker discovery are highlighted. In addition, new developments and future prospects are described. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Subsurface detection of fossil fuel pollutants by photoionization and gas chromatography/mass spectrometry.

    PubMed

    Robbat, Albert; Considine, Thomas; Antle, Patrick M

    2010-09-01

    This paper describes analysis of environmental pollutants at depth without bringing sample to the surface. It is based on an improved 3-stage Peltier freeze trap, which efficiently pre-concentrates volatile coal tar and petroleum hydrocarbons, and an integrated system for detecting pollutants on-line, in real-time by photoionization detection and quantitation by gas chromatography/mass spectrometry (GC/MS) as the probe is advanced into the subsurface. Findings indicate measurement precision and accuracy for volatiles meet EPA criteria for hazardous waste site investigations. When a Teflon membrane inlet is used to detect contaminants in groundwater, its 140 degrees C temperature limit restricts analyte collection in soil to C(2)-phenanthrenes. Two case studies demonstrate the probe is well-suited to tracking petroleum and coal tar plumes from source to groundwater. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  16. Principles and Applications of Liquid Chromatography-Mass Spectrometry in Clinical Biochemistry

    PubMed Central

    Pitt, James J

    2009-01-01

    Liquid chromatography-mass spectrometry (LC-MS) is now a routine technique with the development of electrospray ionisation (ESI) providing a simple and robust interface. It can be applied to a wide range of biological molecules and the use of tandem MS and stable isotope internal standards allows highly sensitive and accurate assays to be developed although some method optimisation is required to minimise ion suppression effects. Fast scanning speeds allow a high degree of multiplexing and many compounds can be measured in a single analytical run. With the development of more affordable and reliable instruments, LC-MS is starting to play an important role in several areas of clinical biochemistry and compete with conventional liquid chromatography and other techniques such as immunoassay. PMID:19224008

  17. Use of Gas Chromatography-Mass Spectrometry (GC-MS) in Nonscience Major Course Laboratory Experiments

    NASA Astrophysics Data System (ADS)

    Kostecka, Keith S.; Lerman, Zafra M.; Angelos, Sanford A.

    1996-06-01

    Gas chromatography-mass spectrometry (GC-MS) has been utilized with nonscience majors in the courses: "Modern Methods in Science: Discovering Molecular Secrets"; "The Extraordinary Chemistry of Ordinary Things"; "From Ozone to Oil Spills: Chemistry, the Environment and You"; and "Crime Lab Chemistry: Solving Crime through Analytical Chemistry". Our efforts have centered on introducing prospective science communicators (film, video, radio, television, and journalism majors) to science relative to their majors and personal interests. Quality lecture-discussion topics, "mystery"-based laboratory activities have assisted in introducing and/or explaining specific areas of chemistry that attempt to reduce fear of subject matter. Students have also used GC-MS, as a form of alternative assessment, in course projects that have been based on their majors, personal interests, and cultural backgrounds. Students have also conducted advanced independent work in different areas of chemistry, including the analysis of nail polishes and lacquers and eleven aromatic compounds present in three different brands of gasoline.

  18. Qualitative Gas Chromatography-Mass Spectrometry Analyses Using Amines as Chemical Ionization Reagent Gases

    NASA Astrophysics Data System (ADS)

    Little, James L.; Howard, Adam S.

    2013-12-01

    Ammonia is a very useful chemical ionization (CI) reagent gas for the qualitative analyses of compounds by positive ion gas chromatography-mass spectrometry (GCMS). The gas is readily available, inexpensive, and leaves no carbon contamination in the MS source. Compounds of interest to our laboratory typically yield abundant protonated or ammoniated species, which are indicative of a compound's molecular weight. Nevertheless, some labile compounds fragment extensively by substitution and elimination reactions and yield no molecular weight information. In these cases, a CI reagent gas mixture of methylamine in methane prepared dynamically was found to be very useful in obtaining molecular weight data. Likewise, deuterated ammonia and deuterated methylamine are useful CI reagent gases for determining the exchangeable protons in organic compounds. Deuterated methylamine CI reagent gas is conveniently prepared by dynamically mixing small amounts of methylamine with excess deuterated ammonia.

  19. Trace detection of meglumine and diatrizoate from Bacillus spore samples using liquid chromatography/mass spectrometry.

    PubMed

    Swider, Catherine; Maguire, Kelly; Rickenbach, Michael; Montgomery, Madeline; Ducote, Matthew J; Marhefka, Craig A

    2012-07-01

    Following the September 11, 2001 terrorist attacks, letters containing Bacillus anthracis were distributed through the United States postal system killing five people. A complex forensic investigation commenced to identify the perpetrator of these mailings. A novel liquid chromatography/mass spectrometry protocol for the qualitative detection of trace levels of meglumine and diatrizoate in dried spore preparations of B. anthracis was developed. Meglumine and diatrizoate are components of radiographic imaging products that have been used to purify bacterial spores. Two separate chromatographic assays using multiple mass spectrometric analyses were developed for the detection of meglumine and diatrizoate. The assays achieved limits of detection for meglumine and diatrizoate of 1.00 and 10.0 ng/mL, respectively. Bacillus cereus T strain spores were effectively used as a surrogate for B. anthracis spores during method development and validation. This protocol was successfully applied to limited evidentiary B. anthracis spore material, providing probative information to the investigators.

  20. Current Applications of Liquid Chromatography/Mass Spectrometry in Pharmaceutical Discovery After a Decade of Innovation

    NASA Astrophysics Data System (ADS)

    Ackermann, Bradley L.; Berna, Michael J.; Eckstein, James A.; Ott, Lee W.; Chaudhary, Ajai K.

    2008-07-01

    Current drug discovery involves a highly iterative process pertaining to three core disciplines: biology, chemistry, and drug disposition. For most pharmaceutical companies the path to a drug candidate comprises similar stages: target identification, biological screening, lead generation, lead optimization, and candidate selection. Over the past decade, the overall efficiency of drug discovery has been greatly improved by a single instrumental technique, liquid chromatography/mass spectrometry (LC/MS). Transformed by the commercial introduction of the atmospheric pressure ionization interface in the mid-1990s, LC/MS has expanded into almost every area of drug discovery. In many cases, drug discovery workflow has been changed owing to vastly improved efficiency. This review examines recent trends for these three core disciplines and presents seminal examples where LC/MS has altered the current approach to drug discovery.

  1. Simultaneous determination of amphetamines and ketamines in urine by gas chromatography/mass spectrometry.

    PubMed

    Lin, Huei Ru; Lua, Ahai Chang

    2006-01-01

    A method for the simultaneous determination of amphetamines and ketamines (ketamine, norketamine and dehydronorketamine) in urine samples by gas chromatography/mass spectrometry was developed and validated. Urine samples were extracted with organic solvent and derivatized with trifluoroacetic anhydride (TFAA). The limits of detection and limits of quantification for each analyte were lower than 19 and 30 ng/mL, respectively. Within-day and between-day precisions were within 0.5% and 10.6%, respectively. Biases for three levels of control samples were within -10.6% and +7.8%. The concentration of dehydronorketamine was greater than those of ketamine or norketamine in 19 of 35 ketamine-positive samples. A group of 110 human urine samples previously determined to contain at least one of the target analytes was analyzed using the new method, and excellent agreement was observed with previous results.

  2. High-speed, low-pressure gas chromatography-mass spectrometry for essential oil analysis.

    PubMed

    Poynter, Samuel D H; Shellie, Robert A

    2008-07-18

    Analysis of parsley and fennel essential oils was performed by using low-pressure gas chromatography-mass spectrometry (GC-MS). The low-pressure instrument configuration was achieved by fitting a GC-MS instrument with a 530microm I.D. capillary column and an appropriate capillary restrictor at the inlet of the column. Comparison of the performance of the low-pressure GC-MS setup was made with fast GC-MS using a narrow-bore capillary column. By comparing the two approaches side-by-side the benefits of low-pressure GC-MS for characterisation of moderately complex essential oils comprising less than 50 detectable components can be fully appreciated. Although efficiency is sacrificed, the improved sample capacity of the 530microm I.D. column leads to higher peak intensities and in-turn better mass spectral library matching thus providing highly satisfactory results.

  3. Confirmatory tests for drugs in the workplace by gas chromatography-mass spectrometry.

    PubMed

    Goldberger, B A; Cone, E J

    1994-07-15

    The Mandatory Guidelines for Federal Workplace Drug Testing Programs require the use of gas chromatography-mass spectrometry (GC-MS) for the confirmation of presumptive positive urine specimens. This review focuses upon GC-MS methods developed specifically for forensic confirmation of amphetamine, methamphetamine, 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid (THC-acid), benzoylecgonine, morphine, codeine and phencyclidine in urine for purposes of workplace drug testing. In addition, current laboratory issues pertaining to each drug class are reviewed. Generally, drug assays utilized either liquid-liquid or solid-phase extraction methods, derivatization if necessary, and GC-MS detection operating in the selected ion monitoring mode or by full scan acquisition.

  4. Characterization of gamma irradiated petrolatum eye ointment base by headspace-gas chromatography-mass spectrometry.

    PubMed

    Hong, Lan; Altorfer, Hans

    2002-06-20

    The effects of gamma irradiation on petrolatum eye ointment base (EOB) and its ingredients (white petrolatum, liquid paraffin, and wool fat) were studied at different irradiation doses. Forty-one volatile radiolysis products were detected and identified by a combined system of headspace-gas chromatography-mass spectrometry (HS-GC-MS). The characteristics of the radiolysis products and the degradation pathway were discussed in each case, respectively. GC method demonstrates that the component distribution patterns of eye ointment as well as its individual ingredients have no differences before and after gamma irradiation. The influence of gamma treatment on EOB was quantitatively determined at 15, 25 and 50 kGy. The concentrations of the radiolysis products increase linearly with increasing doses. Both qualitative and quantitative data show that irradiated eye ointment is safe for human use.

  5. Characterization and quantification of fluoxymesterone metabolite in horse urine by gas chromatography/mass spectrometry.

    PubMed

    Yamada, Masayuki; Aramaki, Sugako; Hosoe, Tomoo; Kurosawa, Masahiko; Kijima-Suda, Isao; Saito, Koichi; Nakazawa, Hiroyuki

    2008-07-01

    Fluoxymesterone, an anabolic steroid with the 17alpha-methyl,17beta-hydroxy group, has been developed as an oral formulation for therapeutic purposes. However, it is also used illegally in racehorses to enhance racing performance. In this study, we detected 9alpha-fluoro-17,17-dimethyl-18-norandrostane-4,13-dien-11beta-ol-3-one by gas chromatography/mass spectrometry (GC/MS), which has not been reported as a fluoxymesterone metabolite so far in horse. It was synthesized for use as a reference standard, and characterized on the basis of (1)H NMR and (13)C NMR spectra, as well as GC/MS EI mass spectra of TMS derivatives. It was excreted as the main metabolite in horse urine, and its reference standard could be synthesized easily. Therefore, this metabolite could be a useful target for a doping test of fluoxymesterone in racehorses.

  6. Gas chromatography-mass spectrometry-based metabolic profiling of cerebrospinal fluid from epileptic dogs.

    PubMed

    Hasegawa, Tetsuya; Sumita, Maho; Horitani, Yusuke; Tamai, Reo; Tanaka, Katsuhiro; Komori, Masayuki; Takenaka, Shigeo

    2014-04-01

    Epilepsy is a common neurological disorder with seizures, but diagnostic approaches in veterinary clinics remain limited. Cerebrospinal fluid (CSF) is a body fluid used for diagnosis in veterinary medicine. In this study, we explored canine epilepsy diagnostic biomarkers using gas chromatography-mass spectrometry (GC-MS)-based metabolic profiling of CSF and multivariate data analysis. Profiles for subjects with idiopathic epilepsy differed significantly from those of healthy controls and subjects with symptomatic epilepsy. Among 60 identified metabolites, the levels of 20 differed significantly among the three groups. Glutamic acid was significantly increased in idiopathic epilepsy, and some metabolites including ascorbic acid were changed in both forms of epilepsy. These findings show that metabolic profiles of CSF differ between idiopathic and symptomatic epilepsy and that metabolites including glutamic acid and ascorbic acid in CSF may be useful for diagnosis of canine epilepsy.

  7. Gas Chromatography-Mass Spectrometry-Based Metabolic Profiling of Cerebrospinal Fluid from Epileptic Dogs

    PubMed Central

    HASEGAWA, Tetsuya; SUMITA, Maho; HORITANI, Yusuke; TAMAI, Reo; TANAKA, Katsuhiro; KOMORI, Masayuki; TAKENAKA, Shigeo

    2013-01-01

    ABSTRACT Epilepsy is a common neurological disorder with seizures, but diagnostic approaches in veterinary clinics remain limited. Cerebrospinal fluid (CSF) is a body fluid used for diagnosis in veterinary medicine. In this study, we explored canine epilepsy diagnostic biomarkers using gas chromatography-mass spectrometry (GC-MS)-based metabolic profiling of CSF and multivariate data analysis. Profiles for subjects with idiopathic epilepsy differed significantly from those of healthy controls and subjects with symptomatic epilepsy. Among 60 identified metabolites, the levels of 20 differed significantly among the three groups. Glutamic acid was significantly increased in idiopathic epilepsy, and some metabolites including ascorbic acid were changed in both forms of epilepsy. These findings show that metabolic profiles of CSF differ between idiopathic and symptomatic epilepsy and that metabolites including glutamic acid and ascorbic acid in CSF may be useful for diagnosis of canine epilepsy. PMID:24334864

  8. [Determination of 10 volatile organic compounds in toys by headspace gas chromatography-mass spectrometry].

    PubMed

    Lü, Qing; Zhang, Qing; Kang, Suyuan; Bai, Hua; Wang, Chao

    2010-08-01

    A headspace gas chromatography-mass spectrometry (HS-GC-MS) method was developed for the determination of 10 residual volatile organic compounds (VOCs) in toys. The experimental conditions such as headspace temperature, headspace time and the analytical conditions of GC-MS were optimized. Toy samples were treated at 140 degrees C for 45 min, and then the evolved products were separated on a DB-624 column, determined by MS and quantified by external standard method. The recoveries were from 79% to 106% and the relative standard deviations (RSDs) were from 0.4% to 5.6%. The linear range was 0.001 - 2.0 microg with a good linear correlation coefficient (r > 0.994 0) and the limits of quantification (LOQ) were less than 0 66 mg/kg. The method is accurate, simple, rapid, and is suitable for the analysis of residual VOCs in various toys.

  9. Determination of amprolium in feed by a liquid chromatography-mass spectrometry method.

    PubMed

    Squadrone, S; Mauro, C; Ferro, G L; Amato, G; Abete, M C

    2008-12-15

    As a consequence of the finding of veterinarian drugs in food European Community banned several compounds like coccidiostats as amprolium (APL). This antibiotic has been used as a preventive and clinical anticoccidial drug in chicken. The 2005/187/CE, 2005/925/EC Recommendations ban the use of amprolium as additive in chicken feed. For this reason a rapid and sensitive liquid chromatography-mass spectrometry (LC-MS) method was developed to detect amprolium in chicken feed following the European community proposed technique (1999/27/EC) for sample preparation. Cause the validation is required for the analytical methods used in feed official control, this method was validated according to 2004/882/EC Regulation.

  10. Analysis of beechwood creosote by gas chromatography-mass spectrometry and high-performance liquid chromatography.

    PubMed

    Ogata, N; Baba, T

    1989-12-01

    Compounds in beechwood creosote were analyzed by gas chromatography-mass spectrometry, and 22 major constituents were identified. Of these, 19 were phenolic compounds, i. e., guaiacol, phenol, two cresol isomers, four methylguaiacol (creosol) isomers, six xylenol isomers, two trimethylphenol isomers, 4-ethylguaiacol, 4-ethyl-5-methylguaiacol, and 4-propylguaiacol. The remaining three were hitherto unpredicted five-membered ring compounds, i. e., 3-methyl-2-hydroxy-2-cyclopenten-1-one, 3,5-dimethyl-2-hydroxy-2-cyclopenten-1-one, and 3-ethyl-2-hydroxy-2-cyclopenten-1-one. The relative quantities of these compounds were also compared with those obtained by high-resolution high-performance liquid chromatography. This report probably represents the first extensive analysis of beechwood creosote.

  11. Determination of glyphosate, glyphosate metabolites, and glufosinate in human serum by gas chromatography-mass spectrometry.

    PubMed

    Motojyuku, Megumi; Saito, Takeshi; Akieda, Kazuki; Otsuka, Hiroyuki; Yamamoto, Isotoshi; Inokuchi, Sadaki

    2008-11-15

    This paper describes an assay for the determination of glyphosate (GLYP), glyphosate metabolites [(aminomethyl) phosphonic acid] (AMPA), and glufosinate (GLUF) in human serum. After protein precipitation using acetonitrile and solid-phase extraction, serum samples were derivatized and analyzed by gas chromatography-mass spectrometry (GC-MS). The assay was linear over a concentration range of 3-100.0 microg/ml for GLYP, AMPA, and GLUF. The overall recoveries for the three compounds were >73%. The intra- and inter-day variations were <15%. Precision and accuracy were 6.4-10.6% and 88.2-103.7%, respectively. The validated method was applied to quantify the GLYP and AMPA content in the serum of a GLYP-poisoned patient. In conclusion, the method was successfully applied for the determination of GLYP and its metabolite AMPA in serum obtained from patient of GLYP-poisoning.

  12. Analysis of Iranian rosemary essential oil: application of gas chromatography-mass spectrometry combined with chemometrics.

    PubMed

    Jalali-Heravi, Mehdi; Moazeni, Rudabeh Sadat; Sereshti, Hassan

    2011-05-06

    This paper focuses on characterization of the components of Iranian rosemary essential oil using gas chromatography-mass spectrometry (GC-MS). Multivariate curve resolution (MCR) approach was used to overcome the problem of background, baseline offset and overlapping/embedded peaks in GC-MS. The analysis of GC-MS data revealed that sixty eight components exist in the rosemary essential oil. However, with the help of MCR this number was extended to ninety nine components with concentrations higher than 0.01%, which accounts for 98.23% of the total relative content of the rosemary essential oil. The most important constituents of the Iranian rosemary are 1,8-cineole (23.47%), α-pinene (21.74%), berbonone (7.57%), camphor (7.21%) and eucalyptol (4.49%).

  13. Preparative monohydroxyflavanone syntheses and a protocol for gas chromatography-mass spectrometry analysis of monohydroxyflavanones.

    PubMed

    Kagawa, Hitoshi; Shigematsu, Asako; Ohta, Shigeru; Harigaya, Yoshihiro

    2005-05-01

    We describe a facile efficient, and preparative approach for monohydroxyflavanone syntheses. Using this protocol, a hydroxyl is regio-selectively introduced at one carbon of a flavanone A- or B-ring per synthesis. The seven possible isomers were each synthesized from the corresponding monomethoxymethoxylated 2'-hydroxychalcones in acidic solution. These monohydroxyflavanones were characterized using a gas chromatography-mass spectrometry (GC-MS) system that incorporated a DB-5 capillary column. Ours is the first report of a preparative synthetic method during which a single hydroxyl can be selectively added to a flavanone A- or B-ring at any position. We are also the first to develop a procedure that separates the seven isomers by GC and characterizes the mass spectra of the isomers. Both the synthetic method and the GC-MS conditions may become important tools during future flavanone metabolism and oxidation studies.

  14. Extraction and quantitation of carfentanil and naltrexone in goat plasma with liquid chromatography-mass spectrometry.

    PubMed

    Hunter, Robert P; Koch, David E; Mutlow, Adrian; Isaza, Ramiro

    2003-08-15

    This method is the first analytical method for the detection and quantitation of carfentanil and naltrexone at clinically relevant concentrations using liquid chromatography-mass spectrometry. Samples were alkalinized with 100 microl of 1 M NaOH and extracted 2x with 2 ml of toluene. The extractions were combined and dried under N(2) at 40 degrees C in a H(2)O bath. Chromatography was performed using a Zirchrom PBD column and a mobile phase of 30:70 acetonitrile/10 mM ammonium acetate and 0.1 mM citrate (pH=4.4) at a flow rate of 0.3 ml/min. The lower limit of quantitation was 8.5 pg/ml for carfentanil and 0.21 ng/ml for naltrexone.

  15. Gas chromatography/mass spectrometry for the determination of nitrosamines in red wine.

    PubMed

    Lona-Ramirez, Fernando J; Gonzalez-Alatorre, Guillermo; Rico-Ramírez, Vicente; Perez-Perez, Ma Cristina I; Castrejón-González, Edgar O

    2016-04-01

    N-nitrosamines (NAms) are highly active carcinogens that have been detected in food and beverages. Currently certain studies report their presence in red wine, while others fail to detect their presence. In this study the head space solid phase micro-extraction technique coupled to gas chromatography-mass spectrometry (HS-SPME-GC-MS) was applied to quantify four NAms in different types of red wine. The technique was found to be a simple, precise, fast and environmentally friendly alternative for the quantification of volatile NAms. A factorial analysis was carried out to evaluate the influence of the parameters on the HS-SPME technique. This is the first study that such analysis has been reported and where NAms in red wine have been quantified using HS-SPME-GC-MS. The method was validated by calculating the linearity, limit of detection and quantification. Two of the four NAms analyzed were found to be present in red wine samples.

  16. Detection of thiazide-based diuretics in equine urine by liquid chromatography/mass spectrometry.

    PubMed

    Garbís, S D; Hanley, L; Kalita, S

    1998-01-01

    Thiazide-based diuretics are included in the list of banned drugs in the horse-racing industry. One effect of their misuse is increased urine flow, contributing to dilution of other doping agents. Their determination is essential in ensuring compliance to horse-racing regulation. This study evaluates the feasibility of using liquid chromatography/mass spectrometry (LC/MS) with electrospray and atmospheric pressure chemical ionization interfaces to analyze thiazidic diuretics in equine urine samples. Existing LC and gas chromatography/MS methods are limited in their applicability to thiazide analysis. Sample preparation, analyte extraction, chromatographic separation, ion-source collision induced dissociation, solvent composition, ionization mode, and ion polarity are discussed. The practicality of LC/MS for this analysis is demonstrated with actual equine administration samples collected at specified time intervals. Detection limits were 270 ng/mL for chlorothiazide, 131 ng/mL for hydrochlorothiazide, and 384 ng/mL for trichlormethiazide.

  17. Verification of chemical composition of commercially available propolis extracts by gas chromatography-mass spectrometry analysis.

    PubMed

    Czyżewska, Urszula; Konończuk, Joanna; Teul, Joanna; Drągowski, Paweł; Pawlak-Morka, Renata; Surażyński, Arkadiusz; Miltyk, Wojciech

    2015-05-01

    Propolis is a resin that is collected by honeybees from various plant sources. Due to its pharmacological properties, it is used in commercial production of nutritional supplements in pharmaceutical industry. In this study, gas chromatography-mass spectrometry was applied for quality control analysis of the three commercial specimens containing aqueous-alcoholic extracts of bee propolis. More than 230 constituents were detected in analyzed products, including flavonoids, chalcones, cinnamic acids and their esters, phenylpropenoid glycerides, and phenylpropenoid sesquiterpenoids. An allergenic benzyl cinnamate ester was also identified in all tested samples. This analytical method allows to evaluate biological activity and potential allergenic components of bee glue simultaneously. Studies on chemical composition of propolis samples may provide new approach to quality and safety control analysis in production of propolis supplementary specimens.

  18. [Determination of primary aromatic amines in crayons gas chromatography-mass spectrometry].

    PubMed

    Kang, Suyuan; Zhang, Qing; Bai, Hua; Wang, Chao; Lü, Qing

    2011-05-01

    A method for the determination of nine primary aromatic amines in crayon by solid phase extraction (SPE) and gas chromatography-mass spectrometry (GC-MS) was developed. The alkanes in the sample were removed with n-hexane. Then the sample was extracted twice with ultrasonic extraction by methanol. The extract was evaporated, then the concentrated solution reacted with the reducing agent (sodium hydrosulfite) for 30 min at 70 degrees C. After the extraction with a diatomite SPE column, the aromatic amines were collected and separated on an HP-5M column, determined by MS. The nine primary aromatic amines can be separated and determined successfully. Under the optimized conditions, the detection limits were 5 mg/kg and the spiked recoveries of the samples were in the range of 86.02%-102.43%. The method is accurate and stable. It can be applied in the analysis of the primary aromatic amine of real crayon samples.

  19. Determination of chemical components derived from 2% chlorhexidine gel degradation using gas chromatography-mass spectrometry.

    PubMed

    Câmara De Bem, Samuel Henrique; Estrela, Carlos; Guedes, Débora Fernandes Costa; Sousa-Neto, Manoel Damião; Pécora, Jesus Djalma

    2014-11-01

    This study determined the chemical components derived from degradation of 2% chlorhexidine (CHX) gel and solution by using gas chromatography-mass spectrometry. Three 2% CHX gels were used to identify the products of CHX gel degradation using gas chromatography-mass spectrometry. A solution of CHX was also evaluated to compare the degradation between gel and solution. Degradation was evaluated in four storage situations (on the worktable with light: on the worktable without light; in the Pasteur oven at 36.5°C without light; and in the refrigerator at 8°C without light). Measurements were made at four time points: initial analysis and 1, 3 and 6 months after. The conversion of CHX into para-chloroaniline in storage situations and in different periods was analyzed statistically using chi-square test (α = 5%). The 2% CHX gel or solution had already degraded vial found within the period of validity, at all time points and for all storage conditions. The amount of para-chloroaniline (pCA) was directly proportional to time in the case of CHX solution, but not in CHX gel due to lack of homogeneity. CHX homogeneity in hydroxyethylcellulose gel was directly dependent on compounding mode. Degradation products, such as para-chloroaniline (pCA), orto- chloroaniline (oCA), meta-chloroaniline (mCA), reactive oxygen species (ROS) and organochlorines (ortho-chlorophenyl isocyanate and 2-amino-5-clorobenzonitrila) were found in 2% CHX gel and solution, regardless of storage conditions or time. In relationship to gel homogenization an alternative to produce 2% CHX gel and a new homogenization method have been developed.

  20. Detecting trace components in liquid chromatography/mass spectrometry data sets with two-dimensional wavelets

    NASA Astrophysics Data System (ADS)

    Compton, Duane C.; Snapp, Robert R.

    2007-09-01

    TWiGS (two-dimensional wavelet transform with generalized cross validation and soft thresholding) is a novel algorithm for denoising liquid chromatography-mass spectrometry (LC-MS) data for use in "shot-gun" proteomics. Proteomics, the study of all proteins in an organism, is an emerging field that has already proven successful for drug and disease discovery in humans. There are a number of constraints that limit the effectiveness of liquid chromatography-mass spectrometry (LC-MS) for shot-gun proteomics, where the chemical signals are typically weak, and data sets are computationally large. Most algorithms suffer greatly from a researcher driven bias, making the results irreproducible and unusable by other laboratories. We thus introduce a new algorithm, TWiGS, that removes electrical (additive white) and chemical noise from LC-MS data sets. TWiGS is developed to be a true two-dimensional algorithm, which operates in the time-frequency domain, and minimizes the amount of researcher bias. It is based on the traditional discrete wavelet transform (DWT), which allows for fast and reproducible analysis. The separable two-dimensional DWT decomposition is paired with generalized cross validation and soft thresholding. The Haar, Coiflet-6, Daubechie-4 and the number of decomposition levels are determined based on observed experimental results. Using a synthetic LC-MS data model, TWiGS accurately retains key characteristics of the peaks in both the time and m/z domain, and can detect peaks from noise of the same intensity. TWiGS is applied to angiotensin I and II samples run on a LC-ESI-TOF-MS (liquid-chromatography-electrospray-ionization) to demonstrate its utility for the detection of low-lying peaks obscured by noise.

  1. ANALYSIS OF TRACE-LEVEL ORGANIC COMBUSTION PROCESS EMISSIONS USING NOVEL MULTIDIMENSIONAL GAS CHROMATOGRAPHY-MASS SPECTROMETRY PROCEDURES

    EPA Science Inventory

    The paper discusses the analysis of trace-level organic combustion process emissions using novel multidimensional gas chromatography-mass spectrometry (MDGC-MS) procedures. It outlines the application of the technique through the analyses of various incinerator effluent and produ...

  2. An Advanced Analytical Chemistry Experiment Using Gas Chromatography-Mass Spectrometry, MATLAB, and Chemometrics to Predict Biodiesel Blend Percent Composition

    ERIC Educational Resources Information Center

    Pierce, Karisa M.; Schale, Stephen P.; Le, Trang M.; Larson, Joel C.

    2011-01-01

    We present a laboratory experiment for an advanced analytical chemistry course where we first focus on the chemometric technique partial least-squares (PLS) analysis applied to one-dimensional (1D) total-ion-current gas chromatography-mass spectrometry (GC-TIC) separations of biodiesel blends. Then, we focus on n-way PLS (n-PLS) applied to…

  3. Introducing Students to Gas Chromatography-Mass Spectrometry Analysis and Determination of Kerosene Components in a Complex Mixture

    ERIC Educational Resources Information Center

    Pacot, Giselle Mae M.; Lee, Lyn May; Chin, Sung-Tong; Marriott, Philip J.

    2016-01-01

    Gas chromatography-mass spectrometry (GC-MS) and GC-tandem MS (GC-MS/MS) are useful in many separation and characterization procedures. GC-MS is now a common tool in industry and research, and increasingly, GC-MS/MS is applied to the measurement of trace components in complex mixtures. This report describes an upper-level undergraduate experiment…

  4. Quantitation of Phenol Levels in Oil of Wintergreen Using Gas Chromatography-Mass Spectrometry with Selected Ion Monitoring

    ERIC Educational Resources Information Center

    Sobel, Robert M.; Ballantine, David S.; Ryzhov, Victor

    2005-01-01

    Industrial application of gas chromatography-mass spectrometry (GC-MS) analysis is a powerful technique that could be used to elucidate components of a complex mixture while offering the benefits of high-precision quantitative analysis. The natural wintergreen oil is examined for its phenol concentration to determine the level of refining…

  5. Analysis of CYP3A inhibitory components of star fruit (Averrhoa carambola L.) using liquid chromatography-mass spectrometry.

    PubMed

    Hosoi, Shinzo; Shimizu, Eri; Arimori, Kazuhiko; Okumura, Manabu; Hidaka, Muneaki; Yamada, Mitsuko; Sakushima, Akiyo

    2008-07-01

    In this study, we analyzed the CYP3A inhibitory components of star fruit Averrhoa carambola L., using liquid chromatography-mass spectrometry (LC-MS). The stereoisomer of procyanidin B1 and B2 and/or the trimer consisting of catechin and/or epicatechin were suggested to be potent inhibitory components.

  6. Quantitation of Phenol Levels in Oil of Wintergreen Using Gas Chromatography-Mass Spectrometry with Selected Ion Monitoring

    ERIC Educational Resources Information Center

    Sobel, Robert M.; Ballantine, David S.; Ryzhov, Victor

    2005-01-01

    Industrial application of gas chromatography-mass spectrometry (GC-MS) analysis is a powerful technique that could be used to elucidate components of a complex mixture while offering the benefits of high-precision quantitative analysis. The natural wintergreen oil is examined for its phenol concentration to determine the level of refining…

  7. An Advanced Analytical Chemistry Experiment Using Gas Chromatography-Mass Spectrometry, MATLAB, and Chemometrics to Predict Biodiesel Blend Percent Composition

    ERIC Educational Resources Information Center

    Pierce, Karisa M.; Schale, Stephen P.; Le, Trang M.; Larson, Joel C.

    2011-01-01

    We present a laboratory experiment for an advanced analytical chemistry course where we first focus on the chemometric technique partial least-squares (PLS) analysis applied to one-dimensional (1D) total-ion-current gas chromatography-mass spectrometry (GC-TIC) separations of biodiesel blends. Then, we focus on n-way PLS (n-PLS) applied to…

  8. Introducing Students to Gas Chromatography-Mass Spectrometry Analysis and Determination of Kerosene Components in a Complex Mixture

    ERIC Educational Resources Information Center

    Pacot, Giselle Mae M.; Lee, Lyn May; Chin, Sung-Tong; Marriott, Philip J.

    2016-01-01

    Gas chromatography-mass spectrometry (GC-MS) and GC-tandem MS (GC-MS/MS) are useful in many separation and characterization procedures. GC-MS is now a common tool in industry and research, and increasingly, GC-MS/MS is applied to the measurement of trace components in complex mixtures. This report describes an upper-level undergraduate experiment…

  9. Determination of cholesterol and triglycerides in serum lipoproteins using flow field-flow fractionation coupled to gas chromatography-mass spectrometry.

    PubMed

    Qureshi, Rashid Nazir; Kaal, Erwin; Janssen, Hans-Gerd; Schoenmakers, Peter J; Kok, Wim Th

    2011-11-14

    Asymmetric flow field flow fractionation (AsFlFFF) was combined with pyrolysis-gas chromatography mass spectrometry for a sized based fractionation and a detailed compositional study of the triglycerides and cholesterol associated with the various lipoprotein subclasses present in human serum. Serum samples were injected in the AsFlFFF instrument and fractionated with a time-delayed exponential decay cross flow program. The fractions collected after AsFlFFF elution were injected into a programmable temperature vaporizer (PTV) GC-injector, containing a fritted liner. A temperature and split-flow program for the PTV injector was optimized for the thermally assisted hydrolysis and methylation of the compounds of interest. The resulting fatty acid and cholesterol methyl esters were separated by GC and characteristic fragment ions were detected by MS. The system was optimized and calibrated with triglyceride and cholesterol standards for quantitative analysis. The possible interference by phospholipids with the quantitative results was investigated and found to be of minor importance. The concentrations and lipoprotein profiles of triglycerides and cholesterol were determined in a pooled serum sample of healthy volunteers and a serum sample of a sepsis patient. The results obtained with the GC-MS approach were compared with those of a previously developed method based on AsFlFFF with a dual enzymatic reaction detection system. A good agreement of the profiles was found, for cholesterol as well as for the triglycerides, even when the GC-MS method quantifies the fatty acids while with the enzymatic reaction method the glycerol concentrations are determined. Total cholesterol and triglyceride concentration values for the serum samples showed good agreement with the results of the standard enzymatic method as used in practice in the university hospital. Copyright © 2011 Elsevier B.V. All rights reserved.

  10. Identification and Quantification of Pesticides in Environmental Waters With Solid Phase Microextraction and Analysis Using Field-Portable Gas Chromatography-Mass Spectrometry

    DTIC Science & Technology

    2004-06-10

    Microextraction and Analysis using Field-Portable Gas Chromatography-Mass Spectrometry Name of Candidate: CPT Michael J. Nack...in the thesis manuscript entitled: Identification and Quantification of Pesticides in Environmental Waters with Solid Phase Microextraction ...Pesticides in Environmental Waters with Solid Phase Microextraction and Analysis using Field-Portable Gas Chromatography-Mass Spectrometry

  11. Correlation of mass spectrometry identified bacterial biomarkers from a fielded pyrolysis-gas chromatography-ion mobility spectrometry biodetector with the microbiological gram stain classification scheme.

    PubMed

    Snyder, A Peter; Dworzanski, Jacek P; Tripathi, Ashish; Maswadeh, Waleed M; Wick, Charles H

    2004-11-01

    A pyrolysis-gas chromatography-ion mobility spectrometry (Py-GC-IMS) briefcase system has been shown to detect and classify deliberately released bioaerosols in outdoor field scenarios. The bioaerosols included Gram-positive and Gram-negative bacteria, MS-2 coliphage virus, and ovalbumin protein species. However, the origin and structural identities of the pyrolysate peaks in the GC-IMS data space, their microbiological information content, and taxonomic importance with respect to biodetection have not been determined. The present work interrogates the identities of the peaks by inserting a time-of-flight mass spectrometry system in parallel with the IMS detector through a Tee connection in the GC module. Biological substances producing ion mobility peaks from the pyrolysis of microorganisms were identified by their GC retention time, matching of their electron ionization mass spectra with authentic standards, and the National Institutes for Standards and Technology mass spectral database. Strong signals from 2-pyridinecarboxamide were identified in Bacillus samples including Bacillus anthracis, and its origin was traced to the cell wall peptidoglycan macromolecule. 3-Hydroxymyristic acid is a component of lipopolysaccharides in the cell walls of Gram-negative organisms. The Gram-negative Escherichia coli organism showed significant amounts of 3-hydroxymyristic acid derivatives and degradation products in Py-GC-MS analyses. Some of the fatty acid derivatives were observed in very low abundance in the ion mobility spectra, and the higher boiling lipid species were absent. Evidence is presented that the Py-GC-ambient temperature and pressure-IMS system generates and detects bacterial biochemical information that can serve as components of a biological classification scheme directly correlated to the Gram stain reaction in microorganism taxonomy.

  12. Identification of novel circulating coffee metabolites in human plasma by liquid chromatography-mass spectrometry.

    PubMed

    Redeuil, Karine; Smarrito-Menozzi, Candice; Guy, Philippe; Rezzi, Serge; Dionisi, Fabiola; Williamson, Gary; Nagy, Kornél; Renouf, Mathieu

    2011-07-22

    This study reports a liquid chromatography-mass spectrometry method for the detection of polyphenol-derived metabolites in human plasma without enzymatic treatment after coffee consumption. Separation of available standards was achieved by reversed-phase ultra performance liquid chromatography and detection was performed by high resolution mass spectrometry in negative electrospray ionization mode. This analytical method was then applied for the identification and relative quantification of circulating coffee metabolites. A total of 34 coffee metabolites (mainly reduced, sulfated and methylated forms of caffeic acid, coumaric acid, caffeoylquinic acid and caffeoylquinic acid lactone) were identified based on mass accuracy (<4 ppm for most metabolites), specific fragmentation pattern and co-chromatography (when standard available). Among them, 19 circulating coffee metabolites were identified for the first time in human plasma such as feruloylquinic acid lactone, sulfated and glucuronidated forms of feruloylquinic acid lactone and sulfated forms of coumaric acid. Phenolic acid derivatives such as dihydroferulic acid, dihydroferulic acid 4'-O-sulfate, caffeic acid 3'-O-sulfate, dimethoxycinnamic acid, dihydrocaffeic acid and coumaric acid O-sulfate appeared to be the main metabolites circulating in human plasma after coffee consumption. The described method is a sensitive and reliable approach for the identification of coffee metabolites in biological fluids. In future, this analytical method will give more confidence in compound identification to provide a more comprehensive assessment of coffee polyphenol bioavailability studies in humans.

  13. Recent development in liquid chromatography/mass spectrometry and emerging technologies for metabolite identification.

    PubMed

    Liang, Yan; Wang, Guangji; Xie, Lin; Sheng, Longsheng

    2011-05-01

    Metabolism studies play a pivotal role in drug discovery and development since the active metabolites is critical to toxicological profile, efficacy and designing new drug candidates. From the instrumentation standpoint, liquid chromatography/mass spectrometry (LC/MS) has secured a central analytical technique for metabolite identification with the continuous developments and improvements in LC and MS technologies. Recently, a wide range of experimental strategies and post acquisition data processing and mining modes have emerged driven by the need to identify and characterize metabolites at ever increasing sensitivity and in ever more complex samples. In this article, the classical and practical mass spectrometry-based techniques, such as low resolution MS (quadruple, ion trap, linear ion trap, etc), high resolution MS (time-of-flight, hybrid time-of-flight instruments, Qrbitrap, Fourier transform ion cyclotron resonance MS, etc) and corresponding post acquisition data processing and mining modes (precursor ion filtering, neutral loss filtering, mass defect filter, isotope-pattern-filtering, etc) are described comprehensively. In addition, this review is also devote to discuss several novel MS technologies (ambient ionization techniques, ion mobility MS, imaging MS, LC/MNR/MS, etc) that hold additional promise for the advancement of metabolism studies. © 2011 Bentham Science Publishers Ltd.

  14. Isolation and derivatization of plasma taurine for stable isotope analysis by gas chromatography-mass spectrometry

    SciTech Connect

    Irving, C.S.; Klein, P.D.

    1980-09-01

    A method for the isolation and derivatization of plasma taurine is described that allows stable isotope determinations of taurine to be made by gas chromatography-mass spectrometry. The isolation procedure can be applied to 0.1 ml of plasma; the recovery of plasma taurine was 70 to 80%. For gc separation, taurine was converted to its dimethylaminomethylene methyl ester derivative which could not be detected by hydrogen flame ionization, but could be monitored readily by NH/sub 3/ chemical ionization mass spectrometry. The derivatization reaction occurred partially on-column and required optimization of injection conditions. Using stable isotope ratiometry multiple ion detection, (M + 2 + H)/sup +//(M + H)/sup +/ ion ratio of natural abundance taurine was determined with a standard deviation of less than +-0.07% of the ratio. The (1,2-/sup 13/C)taurine/taurine mole ratios of standard mixtures could be accurately determined to 0.001. This stable isotope gc-ms method is suitable for studying the plasma kinetics of (1,2-/sup 13/C)taurine in infants who are at risk with respect to taurine depletion.

  15. Issues pertaining to the analysis of buprenorphine and its metabolites by gas chromatography-mass spectrometry.

    PubMed

    Wang, Yu-Shan; Lin, Dong-Liang; Yang, Shu-Ching; Wu, Meng-Yan; Liu, Ray H; Su, Lien-Wen; Cheng, Pai-Sheng; Liu, Chiareiy; Fuh, Ming-Ren

    2010-03-05

    "Substitution therapy" and the use of buprenorphine (B) as an agent for treating heroin addiction continue to gain acceptance and have recently been implemented in Taiwan. Mature and widely utilized gas chromatography-mass spectrometry (GC-MS) technology can complement the low cost and highly sensitive immunoassay (IA) approach to facilitate the implementation of analytical tasks supporting compliance monitoring and pharmacokinetic/pharmacogenetic studies. Issues critical to GC-MS analysis of B and norbuprenorphine (NB) (free and as glucuronides), including extraction, hydrolysis, derivatization, and quantitation approaches were studied, followed by comparing the resulting data against those derived from IA and two types of liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods. Commercial solid-phase extraction devices, highly effective for recovering all metabolites, may not be suitable for the analysis of free B and NB; acetyl-derivatization products exhibit the most favorable chromatographic, ion intensity, and cross-contribution characteristics for GC-MS analysis. Evaluation of IA, GC-MS, and LC-MS/MS data obtained in three laboratories has proven the 2-aliquot GC-MS protocol effective for the determination of free B and NB and their glucuronides.

  16. On-line solid-phase extraction for liquid chromatography-mass spectrometry analysis of pesticides.

    PubMed

    Lucci, Paolo; Núñez, Oscar

    2014-10-01

    Public concern about pesticides in food and water has increased dramatically in the last two decades. In order to guarantee consumers' health and safety, analytical methods that could provide fast and reliable answers without compromising accuracy and precision are required. Sample treatment is probably the most tedious and time-consuming step in many analytical procedures and, despite the significant advances in chromatographic separations and mass spectrometry techniques, sample treatment is still one of the most important parts of the analytical process for achieving good analytical results. Therefore, over the last years, considerable efforts have been made to simplify the stage and to develop fast, accurate, and robust methods that allow the determination of a wide range of pesticides without compromising the integrity of the extraction process. This review article intends to give a short overview of recently developed on-line solid-phase extraction, preconcentration, and clean-up procedures for the determination of pesticides in complex matrices by liquid chromatography-mass spectrometry techniques.

  17. Recent Advance in Liquid Chromatography/Mass Spectrometry Techniques for Environmental Analysis in Japan

    PubMed Central

    Suzuki, Shigeru

    2014-01-01

    The techniques and measurement methods developed in the Environmental Survey and Monitoring of Chemicals by Japan’s Ministry of the Environment, as well as a large amount of knowledge archived in the survey, have led to the advancement of environmental analysis. Recently, technologies such as non-target liquid chromatography/high resolution mass spectrometry and liquid chromatography with micro bore column have further developed the field. Here, the general strategy of a method developed for the liquid chromatography/mass spectrometry (LC/MS) analysis of environmental chemicals with a brief description is presented. Also, a non-target analysis for the identification of environmental pollutants using a provisional fragment database and “MsMsFilter,” an elemental composition elucidation tool, is presented. This analytical method is shown to be highly effective in the identification of a model chemical, the pesticide Bendiocarb. Our improved micro-liquid chromatography injection system showed substantially enhanced sensitivity to perfluoroalkyl substances, with peak areas 32–71 times larger than those observed in conventional LC/MS. PMID:26819891

  18. Direct infusion mass spectrometry or liquid chromatography mass spectrometry for human metabonomics? A serum metabonomic study of kidney cancer.

    PubMed

    Lin, Lin; Yu, Quan; Yan, Xiaomei; Hang, Wei; Zheng, Jiaxin; Xing, Jinchun; Huang, Benli

    2010-11-01

    Serum samples from kidney cancer patients and healthy controls were analyzed by both direct infusion mass spectrometry (DIMS) and liquid chromatography-mass spectrometry (LC-MS) with a high resolution ESI-Q-TOFMS. The classification and biomarker discovery capacities of the two methods were compared, and MS/MS experiments were carried out to identify potential biomarkers. DIMS had comparable classification and prediction capabilities to LC-MS but consumed only ~5% of the analysis time. With regard to biomarker discovery, twenty-three variables were found as potential biomarkers by DIMS, and 48 variables were obtained by LC-MS. DIMS is recommended to be a fast diagnostic method for kidney cancer, while LC-MS is necessary when comprehensive screening of biomarkers is required.

  19. Analysis of polar lipids in the serum from rats fed shiitake by liquid chromatography-mass spectrometry/mass spectrometry.

    PubMed

    Yu, Shanggong; Peng, Min; Ronis, Martin; Badger, Thomas; Fang, Nianbai

    2010-12-22

    Consumption of a shiitake mushroom diet has been reported to have effects on serum phospholipids. However, much less is known about the effect on serum polar lipids including lysophospholipids and free fatty acids. In the present study, the effects of a shiitake diet were evaluated on the basis of identification and quantification of individual polar lipid components in rat serum using liquid chromatography-mass spectrometry/mass spectrometry. By comparison with standards and published data, 50 lysophospholipids and 32 free fatty acids were identified, and the concentrations of 27 polar lipids in rat serum were determined. Shiitake diets decreased the levels of all individual polar lipid components in the serum of male rat. The total level of serum polar lipids in males fed 4% shiitake diets (1365.71 mol/L) was significantly lower than that of the control (2270.26 mol/L). However, shiitake diets did not significantly affect the levels of serum polar lipids in female rats.

  20. Multivariate analysis of progressive thermal desorption coupled gas chromatography-mass spectrometry.

    SciTech Connect

    Van Benthem, Mark Hilary; Mowry, Curtis Dale; Kotula, Paul Gabriel; Borek, Theodore Thaddeus, III

    2010-09-01

    Thermal decomposition of poly dimethyl siloxane compounds, Sylgard{reg_sign} 184 and 186, were examined using thermal desorption coupled gas chromatography-mass spectrometry (TD/GC-MS) and multivariate analysis. This work describes a method of producing multiway data using a stepped thermal desorption. The technique involves sequentially heating a sample of the material of interest with subsequent analysis in a commercial GC/MS system. The decomposition chromatograms were analyzed using multivariate analysis tools including principal component analysis (PCA), factor rotation employing the varimax criterion, and multivariate curve resolution. The results of the analysis show seven components related to offgassing of various fractions of siloxanes that vary as a function of temperature. Thermal desorption coupled with gas chromatography-mass spectrometry (TD/GC-MS) is a powerful analytical technique for analyzing chemical mixtures. It has great potential in numerous analytic areas including materials analysis, sports medicine, in the detection of designer drugs; and biological research for metabolomics. Data analysis is complicated, far from automated and can result in high false positive or false negative rates. We have demonstrated a step-wise TD/GC-MS technique that removes more volatile compounds from a sample before extracting the less volatile compounds. This creates an additional dimension of separation before the GC column, while simultaneously generating three-way data. Sandia's proven multivariate analysis methods, when applied to these data, have several advantages over current commercial options. It also has demonstrated potential for success in finding and enabling identification of trace compounds. Several challenges remain, however, including understanding the sources of noise in the data, outlier detection, improving the data pretreatment and analysis methods, developing a software tool for ease of use by the chemist, and demonstrating our belief that

  1. Measurement of 8-hydroxy-2'-deoxyguanosine in DNA by high-performance liquid chromatography-mass spectrometry: comparison with measurement by gas chromatography-mass spectrometry.

    PubMed

    Dizdaroglu, M; Jaruga, P; Rodriguez, H

    2001-02-01

    Measurement of 8-hydroxy-2'-deoxyguanosine (8-OH-dGuo) in DNA by high-performance liquid chromatography/mass spectrometry (LC/MS) was studied. A methodology was developed for separation by LC of 8-OH-dGuo from intact and modified nucleosides in DNA hydrolyzed by a combination of four enzymes: DNase I, phosphodiesterases I and II and alkaline phosphatase. The atmospheric pressure ionization-electrospray process was used for mass spectral measurements. A stable isotope-labeled analog of 8-OH-dGuo was used as an internal standard for quantification by isotope-dilution MS (IDMS). Results showed that LC/IDMS with selected ion-monitoring (SIM) is well suited for identification and quantification of 8-OH-dGuo in DNA at background levels and in damaged DNA. The sensitivity level of LC/IDMS-SIM was found to be comparable to that reported previously using LC-tandem MS (LC/MS/MS). It was found that approximately five lesions per 10(6) DNA bases can be detected using amounts of DNA as low as 2 microgram. The results also suggest that this lesion may be quantified in DNA at levels of one lesion per 10(6) DNA bases, or even lower, when more DNA is used. Up to 50 microgram of DNA per injection were used without adversely affecting the measurements. Gas chromatography/isotope-dilution MS with selected-ion monitoring (GC/IDMS-SIM) was also used to measure this compound in DNA following its removal from DNA by acidic hydrolysis or by hydrolysis with Escherichia coli Fpg protein. The background levels obtained by LC/IDMS-SIM and GC/IDMS-SIM were almost identical. Calf thymus DNA and DNA isolated from cultured HeLa cells were used for this purpose. This indicates that these two techniques can provide similar results in terms of the measurement of 8-OH-dGuo in DNA. In addition, DNA in buffered aqueous solution was damaged by ionizing radiation at different radiation doses and analyzed by LC/IDMS-SIM and GC/IDMS-SIM. Again, similar results were obtained by the two techniques. The

  2. Determination of cyclamate in urine by derivatized gas chromatography-mass spectrometry.

    PubMed

    Idris, Mohd; Middha, Deepak; Rasool, Shaik N; Shukla, Sudhir K; Baggi, Tulsidas R

    2013-01-01

    It is important in toxicological/drug screening work to rule out the possible interfering analytes, to eliminate the false positive or negative results. In this paper, we describe a simple, selective, and sensitive derivatized GC-MS method for the determination of cyclohexylsulfamic acid (cyclamate) in urine. Elite- 5MS capillary column was used for the separation of analytes and detection using GC-MS. The analysis was carried out in selected ion monitoring mode (SIM) in the range of 26 to 200 using m/z values of 57, 30, 55, 41, 44, 67, 82, 98, and 39. The method is based on the conversion of cyclamate into nitroso derivative of cyclamate followed by its gas chromatography-mass spectrometry determination. The limit of detection, limit of quantitation, and linearity range of the proposed method were found to be 0.2 μg/ ml, 0.7 μg/ml, and 1-15 μg/ml, respectively. The recovery of the present method is in the range of 88-94%. The proposed method can be applied for detection and quantification of cyclamate in urine.

  3. Determination of cyclamate in urine by derivatized gas chromatography-mass spectrometry

    PubMed Central

    Idris, Mohd; Middha, Deepak; Rasool, Shaik N.; Shukla, Sudhir K.; Baggi, Tulsidas R.

    2013-01-01

    Aim: It is important in toxicological/drug screening work to rule out the possible interfering analytes, to eliminate the false positive or negative results. In this paper, we describe a simple, selective, and sensitive derivatized GC-MS method for the determination of cyclohexylsulfamic acid (cyclamate) in urine. Materials and Methods: Elite- 5MS capillary column was used for the separation of analytes and detection using GC-MS. The analysis was carried out in selected ion monitoring mode (SIM) in the range of 26 to 200 using m/z values of 57, 30, 55, 41, 44, 67, 82, 98, and 39. Results and Discussion: The method is based on the conversion of cyclamate into nitroso derivative of cyclamate followed by its gas chromatography-mass spectrometry determination. The limit of detection, limit of quantitation, and linearity range of the proposed method were found to be 0.2 μg/ ml, 0.7 μg/ml, and 1-15 μg/ml, respectively. The recovery of the present method is in the range of 88-94%. Conclusion: The proposed method can be applied for detection and quantification of cyclamate in urine. PMID:23559823

  4. In situ Analysis of Organic Compounds on Mars using Chemical Derivatization and Gas Chromatography Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Glavin, D. P.; Buch, A.; Cabane, M.; Coll, P.; Navarro-Gonzalez, R.; Mahaffy, P. R.

    2005-01-01

    One of the core science objectives of NASA's 2009 Mars Science Laboratory (MSL) mission is to determine the past or present habitability of Mars. The search for key organic compounds relevant to terrestrial life will be an important part of that assessment. We have developed a protocol for the analysis of amino acids and carboxylic acids in Mars analogue materials using gas chromatography mass spectrometry (GCMS). As shown, a variety of carboxylic acids were readily identified in soil collected from the Atacama Desert in Chile at part-per-billion levels by GCMS after extraction and chemical derivatization using the reagent N,N-tert.-butyl (dimethylsilyl) trifluoroacetamide (MTBSTFA). Several derivatized amino acids including glycine and alanine were also detected by GCMS in the Atacama soil at lower concentrations (chromatogram not shown). Lacking derivatization capability, the Viking pyrolysis GCMS instruments could not have detected amino acids and carboxylic acids, since these non-volatile compounds require chemical transformation into volatile species that are stable in a GC column. We are currently optimizing the chemical extraction and derivatization technique for in situ GCMS analysis on Mars. Laboratory results of analyses of Atacama Desert samples and other Mars analogue materials using this protocol will be presented.

  5. [Determination of organotin compounds in textile auxiliaries by gas chromatography-mass spectrometry].

    PubMed

    Li, Yanming; Hu, Yongjie; Liu, Jinhua; Guo, Yuliang; Wang, Guiqin

    2011-04-01

    A gas chromatography-mass spectrometry (GC-MS) method has been developed for the determination of dibutyltin (DBT), tributyltin (TBT) and triphenyltin (TPhT) in textile auxiliaries. The sample was first extracted with n-hexane in acetate buffer solution (pH 4.0) under ultrasonication (for hydrophobic sample) or oscillation extraction (for hydrophilic sample) and then derivatized with sodium tetraethylborate in tetrahydrofuran. The derivative was determined by GC-MS in selected ion monitoring (SIM) mode. The separation and quantification were achieved using a Rxi-5 ms silica capillary column (30 m x 0.25 mm x 0.25 microm). The linear ranges were 0.1-8.0 mg/L for both DBT and TBT, and 0.1-4.0 mg/L for TPhT. There were good linear relationships between the peak area and concentration in the linear ranges and the correlation coefficients (r2) were 0.9994-0.9998. The detection limits (LOD) were from 0.003 mg/L to 0.005 mg/L. The average recoveries of these organotin compounds at the three spiked levels of 4.0, 10.0 and 40.0 mg/kg were 92.6%-108.0% with the relative standard deviations (RSDs) of 2.5%-10.2%. The method is simple and accurate for simultaneous analysis of the DBT, TBT and TPhT in textile auxiliaries.

  6. Chemical Discrimination in Turbulent Gas Mixtures with MOX Sensors Validated by Gas Chromatography-Mass Spectrometry

    PubMed Central

    Fonollosa, Jordi; Rodríguez-Luján, Irene; Trincavelli, Marco; Vergara, Alexander; Huerta, Ramón

    2014-01-01

    Chemical detection systems based on chemo-resistive sensors usually include a gas chamber to control the sample air flow and to minimize turbulence. However, such a kind of experimental setup does not reproduce the gas concentration fluctuations observed in natural environments and destroys the spatio-temporal information contained in gas plumes. Aiming at reproducing more realistic environments, we utilize a wind tunnel with two independent gas sources that get naturally mixed along a turbulent flow. For the first time, chemo-resistive gas sensors are exposed to dynamic gas mixtures generated with several concentration levels at the sources. Moreover, the ground truth of gas concentrations at the sensor location was estimated by means of gas chromatography-mass spectrometry. We used a support vector machine as a tool to show that chemo-resistive transduction can be utilized to reliably identify chemical components in dynamic turbulent mixtures, as long as sufficient gas concentration coverage is used. We show that in open sampling systems, training the classifiers only on high concentrations of gases produces less effective classification and that it is important to calibrate the classification method with data at low gas concentrations to achieve optimal performance. PMID:25325339

  7. Identification and differentiation of dragon's blood in works of art using gas chromatography/mass spectrometry.

    PubMed

    Baumer, Ursula; Dietemann, Patrick

    2010-06-01

    Dragon's blood is a common but non-specific name for red-coloured resins that are produced by various plants, particularly exudations from plant species belonging to the genera Dracaena and Daemonorops. Although dragon's blood is mentioned in historic sources as a colourant, it has hardly ever been identified in real artworks. This paper reports the identification and discrimination of dragon's blood produced by Dracaena cinnabari, Dracaena draco as well as Daemonorops draco and Daemonorops micracantha by means of gas chromatography/mass spectrometry (GC/MS) within the context of a routine analysis of binding media used in works of art. The detection of specific flavonoid marker compounds in both underivatised and methylated methanol extracts provided the first evidence for the use of dragon's blood from all four species in various works of art from the fifteenth to nineteenth centuries. Dragon's blood was mainly used as a red colourant in gold lacquers as well as translucent glazes and paints, e.g. in reverse-glass paintings (Hinterglasmalerei).

  8. Evaluation of the quality of sandalwood essential oils by gas chromatography-mass spectrometry.

    PubMed

    Howes, Melanie-Jayne R; Simmonds, Monique S J; Kite, Geoffrey C

    2004-03-05

    Trade and historic oils from 'sandalwoods', labelled as Amyris balsamifera, Eremophila mitchelli, Fusanus acuminatus (= Santalum acuminatum), Santalum album, S. austrocaledonicum, S. latifolium, S. spicatum and S. yasi, were assessed using gas chromatography-mass spectrometry (GC-MS). Using GC-MS, none of the oils assessed complied with the internationally recognised standard of a 90% santalol content, and only about half of the trade sandalwood oils met with recent International Organisation for Standardisation standards. The majority of trade oils, reportedly from S. album, contained approximately 50-70% santalols (Z-alpha and Z-beta). Thus, the internationally recognised specification (90% santalols) for S. album requires re-evaluation by more efficient analysis methods. In view of the issues associated with the quality of sandalwood oils being traded, specifications of > or = 43% Z-alpha-santalol and > or = 18% Z-beta-santalol for S. album oil estimated by GC-MS are suggested. GC-MS are recommended as it assists with authentication and quality control issues associated with sandalwood oils.

  9. Multi-class method for biomonitoring of hair samples using gas chromatography-mass spectrometry.

    PubMed

    Martín, Julia; Möder, Monika; Gaudl, Alexander; Alonso, Esteban; Reemtsma, Thorsten

    2015-11-01

    Currently, non-invasive biomonitoring of human exposure to organic pollutants bases upon the analysis mainly of urine and human breast milk. While mostly persistent organic pollutants are the center of interest, the aim of our study was to develop a method for the determination of different chemical classes of emerging pollutants (organophosphorus flame retardants, plastic additives such as phthalates, bisphenol A, insecticides, antimicrobials, preservatives and musk fragrances) in hair by gas chromatography-mass spectrometry. The preferred sample preparation included hydrolysis of the hair with trifluoroacetic acid in methanol followed by a liquid-liquid extraction using hexane/ethyl acetate. The validated method is characterized by recoveries higher than 77 % for most analytes, relative standard deviations below 16 % and limits of detection between 2 pg mg(-1) (HHCB) and 292 pg mg(-1) (propylparaben) using 50 mg of dry hair. After respective blank corrections, bis-(2-ethylhexyl)phthalate (DEHP) and the musk fragrance HHCB were the predominant compounds determined in all hair samples at concentrations between 32 and 59 ng mg(-1) and 0.8-13 ng mg(-1), respectively. The bactericide triclosan and the insect repellent N,N-diethyl-3-methylbenzamide (DEET) were detected in selected hair samples at 2 and 0.8 ng mg(-1), respectively.

  10. Headspace Analysis of Philippine Civet Coffee Beans Using Gas Chromatography-Mass Spectrometry and Electronic Nose

    NASA Astrophysics Data System (ADS)

    Ongo, E.; Sevilla, F.; Antonelli, A.; Sberveglieri, G.; Montevecchi, G.; Sberveglieri, V.; de Paola, E. L.; Concina, I.; Falasconi, M.

    2011-11-01

    Civet coffee, the most expensive and best coffee in the world, is an economically important export product of the Philippines. With a growing threat of food adulteration and counterfeiting, a need for quality authentication is essential to protect the integrity and strong market value of Philippine civet coffee. At present, there is no internationally accepted method of verifying whether a bean is an authentic civet coffee. This study presented a practical and promising approach to identify and establish the headspace qualitative profile of Philippine civet coffee using electronic nose (E-nose) and gas chromatography-mass spectrometry (GC-MS). E-nose analysis revealed that aroma characteristic is one of the most important quality indicators of civet coffee. The findings were supported by GC-MS analysis. Principal component analysis (PCA) exhibited a clearly separated civet coffees from their control beans. The chromatographic fingerprints indicated that civet coffees differed with their control beans in terms of composition and concentration of individual volatile constituents.

  11. Quantitative Metabolome Analysis Based on Chromatographic Peak Reconstruction in Chemical Isotope Labeling Liquid Chromatography Mass Spectrometry.

    PubMed

    Huan, Tao; Li, Liang

    2015-07-21

    Generating precise and accurate quantitative information on metabolomic changes in comparative samples is important for metabolomics research where technical variations in the metabolomic data should be minimized in order to reveal biological changes. We report a method and software program, IsoMS-Quant, for extracting quantitative information from a metabolomic data set generated by chemical isotope labeling (CIL) liquid chromatography mass spectrometry (LC-MS). Unlike previous work of relying on mass spectral peak ratio of the highest intensity peak pair to measure relative quantity difference of a differentially labeled metabolite, this new program reconstructs the chromatographic peaks of the light- and heavy-labeled metabolite pair and then calculates the ratio of their peak areas to represent the relative concentration difference in two comparative samples. Using chromatographic peaks to perform relative quantification is shown to be more precise and accurate. IsoMS-Quant is integrated with IsoMS for picking peak pairs and Zero-fill for retrieving missing peak pairs in the initial peak pairs table generated by IsoMS to form a complete tool for processing CIL LC-MS data. This program can be freely downloaded from the www.MyCompoundID.org web site for noncommercial use.

  12. Detection of methamphetamine and its main metabolite in fingermarks by liquid chromatography-mass spectrometry.

    PubMed

    Zhang, Ting; Chen, Xueguo; Yang, Ruiqin; Xu, Yingjian

    2015-03-01

    A sensitive and efficient method applying liquid chromatography-mass spectrometry for the analysis of methamphetamine and its main metabolite in fingermark deposits was described. Using this method, good linear relationship of methamphetamine was obtained in the range of 0.005μg to 0.5μg per cotton swab, the limit of detection was 1.5ng per cotton swab, the limit of quantitation was 5.0ng per cotton swab and the average values of recovery ratios were above 70.1%. Moreover, the influence factors for the detection of methamphetamine in fingermarks, such as kinds of substrates, development methods and extraction methods, were all discussed in details. The results showed that good recovery ratios could be obtained on painted wood and smooth substrates surfaces. Development methods in commercial powder could not influence the quality of examination of exogenous drug in latent fingermark. Furthermore, the results indicated that the method mentioned here could be applied in the analysis of forensic trace evidences and samples obtained in clinically addicted cases.

  13. Analysis of isothiazolinones in environmental waters by gas chromatography-mass spectrometry.

    PubMed

    Rafoth, Astrid; Gabriel, Sabine; Sacher, Frank; Brauch, Heinz-Jürgen

    2007-09-14

    This paper describes an analytical method for the determination of five biocides of isothiazolinone type (2-methyl-3-isothiazolinone (MI), 5-chloro-2-methyl-3-isothiazolinone (CMI), 1,2-benzisothiazolinone (BIT), 2-octyl-3-isothiazolinone (OI), 4,5-dichloro-2-octyl-3-isothiazolinone (DCOI)) in environmental waters. The method is based on pre-concentration of the analytes by solid-phase extraction onto a mixture of a polymeric material and RP-C18 material and subsequent determination by gas chromatography-mass spectrometry (GC-MS). One of the target compounds (BIT) is derivatised with diazomethane after pre-concentration to improve its chromatographic performance. The method was optimised with respect to pre-concentration conditions (liquid-liquid extraction versus solid-phase extraction, solid-phase material, elution solvent and volume) and extensively validated. Applying the method to surface waters, groundwaters, and drinking waters, limits of detection between 0.01 and 0.1 microg/l could be achieved and the repeatability was below 10% for all compounds except for MI. Additional investigations showed that the stability of the isothiazolinones in environmental waters is limited and sample storage at 4 degrees C is mandatory to preserve the target biocides. First investigations of influents and effluents of a wastewater treatment plant showed that conventional wastewater treatment exhibits a high efficiency for removal of the isothiazolinones. In river waters, the target isothiazolinones could not be detected.

  14. Isotope dilution gas chromatography/mass spectrometry method for determination of pyrethroids in apple juice.

    PubMed

    Wong, Siu-kay; Yu, Kwok-chiu; Lam, Chi-ho

    2010-03-01

    This paper presents the development of a highly precise and accurate analytical method for the determination of three matrix-bound pyrethroids, namely, cypermethrin, permethrin, and bifenthrin, using an isotope dilution gas chromatography/mass spectrometry technique. Identification of the analytes was confirmed under selective ion monitoring mode by the presence of two dominant ion fragments within specific time windows and matching of relative ion intensities of the ions concerned in samples and calibration standards. Quantitation was based on the measurement of concentration ratios of the natural and isotope analogues in the sample and calibration blends. Intraday and interday repeatabilities of replicate analyses of the pyethroids in an apple juice sample were below 0.5%. The expanded relative uncertainty ranged from 3 to 6%, which was significantly lower than the range obtained using internal or external calibration methods. As a labeled analogue is not available for bifenthrin, bifenthrin was determined using labeled cis-permethrin as the internal standard. The results were counterchecked by a gas chromatography-electron capture detection technique using PCB 209 as the internal standard. The method developed was applied to a recent pilot study organized by CCQM and the results were consistent with those of other participants.

  15. Determination of emulsion explosives with Span-80 as emulsifier by gas chromatography-mass spectrometry.

    PubMed

    Tian, Fei-Fei; Yu, Jing; Hu, Jia-Hong; Zhang, Yong; Xie, Meng-Xia; Liu, Yuan; Wang, Xiang-Feng; Liu, Hai-Ling; Han, Jie

    2011-06-03

    A novel approach for identification and determination of emulsion explosives with Span-80 (sorbitol mono-oleate) as the emulsifier and their postblast residues by gas chromatography-mass spectrometry (GC-MS) has been developed. 24 kinds of emulsion explosives collected have been processed by transesterification reaction with metholic KOH solution and the emulsifier has turned into methyl esters of fatty acids. From the peak area ratios of their methyl esters, most of these emulsion explosives can be differentiated. In order to detect the postblast residues of emulsion explosives, the sorbitols in the emulsifier Span-80 obtained after transesterification reaction have been further derivatized by silylation reaction with N,O-bis-(trimethylsilyl)trifluoroacetamide (BSTFA) containing 1% trimethylchlorosilane (TMCS) as the derivatizing reagent. The derivatization conditions were optimized and the derivatives were determined by GC-MS. The results showed that the silylation derivatives of sorbitol and it isomers, combined with hydrocarbon compounds and methyl esters of fatty acids, were the characteristic components for identification of the emulsion explosives. The established approach was applied to analyze the postblast residues of emulsion explosives. It has been found that the method was sensitive and specific, especially when detecting the derivatives of sorbitol and its isomers by GC-MS in selecting ion mode. The information of the characteristic components can help probe the origin of the emulsion explosives and providing scientific evidences and clues for solving the crimes of the emulsion explosive explosion. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Metabolomic Analysis Using Liquid Chromatography/Mass Spectrometry for Gastric Cancer.

    PubMed

    Liang, Qun; Wang, Cong; Li, Binbing

    2015-08-01

    Metabolomics is a post-genomics research field for analysis of low molecular weight compounds in biological samples and has shown great potentials for elucidating complex mechanisms associated with diseases. However, metabolomics studies on gastric cancer (GC), which is the second leading cause of cancer death worldwide, remain scarce, and the molecular mechanisms to metabolomics phenotypes are also still not fully understood. This study reports that the metabolic pathways can be exploited as biomarkers for diagnosis and treatment of GC progression as a case study. Importantly, the urinary metabolites and metabolic patterns were analyzed by high-throughput liquid chromatography mass spectrometry (LC-MS) metabolomics strategy coupled with chemometric evaluation. Sixteen metabolites (nine upregulated and seven downregulated) were differentially expressed and may thus serve as potential urinary biomarkers for human GC. These metabolites were mainly involved in multiple metabolic pathways, including citrate cycle (malic acid, succinic acid, 2-oxoglutarate, citric acid), cyanoamino acid metabolism (glycine, alanine), primary bile acid biosynthesis (glycine, taurine, glycocholic acid), arginine and proline metabolism (urea, L-proline), and fatty acid metabolism (hexadecanoic acid), among others. Network analysis validated close association between these identified metabolites and altered metabolic pathways in a variety of biological processes. These results suggest that urine metabolic profiles have great potential in detecting GC and may aid in understanding its underlying mechanisms. It provides insight into disease pathophysiology and can serve as the basis for developing disease biomarkers and therapeutic interventions for GC diseases.

  17. Determination of beta-hydroxybutyrate in blood and urine using gas chromatography- mass spectrometry.

    PubMed

    Hassan, Huda M A; Cooper, Gail A A

    2009-10-01

    Beta-hydroxybutyrate (BHB) is considered a potential biomarker for alcoholic ketoacidosis (AKA). A robust and sensitive method was developed and validated for the quantitative determination of BHB in postmortem blood and urine using deuterated gamma-hydroxybutyrate as an internal standard. Samples were analyzed by gas chromatography-mass spectrometry following liquid-liquid extraction and silyl derivatization. The limits of detection and lower limits of quantification in blood and urine were 2 and 7 mg/L and 2 and 6 mg/L, respectively. The interday and intraday precision was measured by coefficients of variation for blood and urine and ranged from 1.0 to 12.4% for quality control samples spiked at 50 and 300 mg/L. The linear range of 50-500 mg/L resulted in an average correlation of R(2) > 0.99, and the average extraction recoveries in blood and urine were >or= 82% and >or= 59%, respectively. BHB remains stable in blood spiked at a concentration of 300 mg/L for 15 days when stored within a refrigerator (2-5 degrees C). Postmortem blood and urine samples were analyzed using the validated method for cases where the deceased had a history of chronic alcohol abuse to establish the use of BHB as a potential marker of AKA.

  18. EIder: A compound identification tool for gas chromatography mass spectrometry data.

    PubMed

    Koo, Imhoi; Kim, Seongho; Shi, Biyun; Lorkiewicz, Pawel; Song, Ming; McClain, Craig; Zhang, Xiang

    2016-05-27

    We report software entitled EIder (EI mass spectrum identifier) that provides users with eight literature reported spectrum matching algorithms for compound identification from gas chromatography mass spectrometry (GC-MS) data. EIder calculates retention index according to experimental conditions categorized by column class, column type and data type, where 9 empirical distribution functions of the absolute retention index deviation to its mean value were constructed using the National Institute of Standards and Technology (NIST) 2011 retention index database to improve the accuracy of compound identification. EIder filters compound candidates based on elementary composition and derivatization reagent, and automatically adds the molecular information of the native compound to each derivatized compound using a manually created database. When multiple samples are analyzed together, EIder performs cross-sample alignment and provides an option of using an average mass spectrum for compound identification. Furthermore, a suite of graphical user interfaces are implemented in EIder to allow users to both manually and automatically modify the identification results using experimental information at various analysis stages. Analysis of three types of GC-MS datasets indicates that the developed EIder software can improve the accuracy of compound identification.

  19. Study on volatile components in salami by reverse carrier gas headspace gas chromatography-mass spectrometry.

    PubMed

    Procida, G; Conte, L S; Fiorasi, S; Comi, G; Favretto, L G

    1999-01-08

    Salami are a typical seasoned sausage of Italy; a number of types are produced, according to local traditional recipes. As industrial production has taken place, a number of problems rise in obtaining products similar to the traditional ones. The use of selected microbial starters is permitted by Italian law for some years and at present, microbiological research is engaged in selecting starters similar to the ones isolated from traditional products, with the aim of obtaining organoleptic characteristics close to the ones of traditional recipes. A study was carried out concerning the characterisation of volatile components of salami by headspace capillary gas chromatography-mass spectrometry. As during the sampling step, analytes could reach the analytical column, the carrier gas rate was back flushed in the latter, while a pre column was used as cold trap. Then GC-MS analysis follows. By these techniques, we were able to highlight typical profiles of different salami, as well as monitoring the ripening of a traditional and a starter added salami. Main peaks are of fermentative origin, while also peaks from spices were detected. Ethyl propionate was used as internal standard to be able to normalise the peaks amounts.

  20. Metabolomics by Gas Chromatography-Mass Spectrometry: the combination of targeted and untargeted profiling

    PubMed Central

    Fiehn, Oliver

    2016-01-01

    Gas chromatography-mass spectrometry (GC-MS)-based metabolomics is ideal for identifying and quantitating small molecular metabolites (<650 daltons), including small acids, alcohols, hydroxyl acids, amino acids, sugars, fatty acids, sterols, catecholamines, drugs, and toxins, often using chemical derivatization to make these compounds volatile enough for gas chromatography. This unit shows that on GC-MS- based metabolomics easily allows integrating targeted assays for absolute quantification of specific metabolites with untargeted metabolomics to discover novel compounds. Complemented by database annotations using large spectral libraries and validated, standardized standard operating procedures, GC-MS can identify and semi-quantify over 200 compounds per study in human body fluids (e.g., plasma, urine or stool) samples. Deconvolution software enables detection of more than 300 additional unidentified signals that can be annotated through accurate mass instruments with appropriate data processing workflows, similar to liquid chromatography-MS untargeted profiling (LC-MS). Hence, GC-MS is a mature technology that not only uses classic detectors (‘quadrupole’) but also target mass spectrometers (‘triple quadrupole’) and accurate mass instruments (‘quadrupole-time of flight’). This unit covers the following aspects of GC-MS-based metabolomics: (i) sample preparation from mammalian samples, (ii) acquisition of data, (iii) quality control, and (iv) data processing. PMID:27038389

  1. Mixture model normalization for non-targeted gas chromatography/mass spectrometry metabolomics data.

    PubMed

    Reisetter, Anna C; Muehlbauer, Michael J; Bain, James R; Nodzenski, Michael; Stevens, Robert D; Ilkayeva, Olga; Metzger, Boyd E; Newgard, Christopher B; Lowe, William L; Scholtens, Denise M

    2017-02-02

    Metabolomics offers a unique integrative perspective for health research, reflecting genetic and environmental contributions to disease-related phenotypes. Identifying robust associations in population-based or large-scale clinical studies demands large numbers of subjects and therefore sample batching for gas-chromatography/mass spectrometry (GC/MS) non-targeted assays. When run over weeks or months, technical noise due to batch and run-order threatens data interpretability. Application of existing normalization methods to metabolomics is challenged by unsatisfied modeling assumptions and, notably, failure to address batch-specific truncation of low abundance compounds. To curtail technical noise and make GC/MS metabolomics data amenable to analyses describing biologically relevant variability, we propose mixture model normalization (mixnorm) that accommodates truncated data and estimates per-metabolite batch and run-order effects using quality control samples. Mixnorm outperforms other approaches across many metrics, including improved correlation of non-targeted and targeted measurements and superior performance when metabolite detectability varies according to batch. For some metrics, particularly when truncation is less frequent for a metabolite, mean centering and median scaling demonstrate comparable performance to mixnorm. When quality control samples are systematically included in batches, mixnorm is uniquely suited to normalizing non-targeted GC/MS metabolomics data due to explicit accommodation of batch effects, run order and varying thresholds of detectability. Especially in large-scale studies, normalization is crucial for drawing accurate conclusions from non-targeted GC/MS metabolomics data.

  2. [Analysis of volatile oil of garlic by gas chromatography-mass spectrometry].

    PubMed

    Guo, Xiaofei; Du, Ailing; Guan, Congsheng; Pan, Guangmin; Du, Aiqin; Wang, Weiqiang

    2005-09-01

    The volatile oil of garlic was extracted by hydrodistillation method and gas chromatography-mass spectrometry was applied to analyse the compounds in the oil. The best extraction conditions for high-content, effective components were obtained through optimization. The capillary column was an HP-5MS column (25 mm x 0.25 mm i.d. x 0.25 microm); oven temperature increased with a rate of 5 degrees C /min from 80 to 300 degrees C, and then maintained for 20 min; sample size of 1 microL; split ratio of 100:1; carrier gas of helium (1 mL/min). Mass spectra were obtained at 70 eV. The temperatures of injector base, ionization source were maintained at 270 degrees C, 230 degrees C respectively. Under these conditions, twenty compounds in the volatile oil of garlic were isolated and identified, and the content of each was determined. Sulfur-containing compounds were found to be the principal components, of which the major compound was diallyl trisulfide with the content of more than 30%, which is higher than the others in the literature. The experimental results also indicated that hydrodistillation method is an effective method for officinal component extraction. In addition, it was also demonstrated that the garlic volatile oil was stable when stored at 0 degrees C for 6 months.

  3. Evaluation of column hardware on liquid chromatography-mass spectrometry of phosphorylated compounds.

    PubMed

    Sakamaki, Hiroshi; Uchida, Takeharu; Lim, Lee Wah; Takeuchi, Toyohide

    2015-02-13

    The influences of column hardware, such as chromatographic tubes and frits, on liquid chromatography-mass spectrometry (LC-MS) analysis of phosphorylated compounds were evaluated. The signal to noise ratio (S/N) and the intensity of flavin adenine dinucleotide (FAD) using a glass lined tube and polyethylene frit (GL-PE) column was approximately 170 and 90 times higher, respectively, than those using conventional stainless steel tube and stainless steel frit (S-S) column. In addition, the retention time of FAD using GL-PE column was the shortest compared to other columns. Interaction between phosphorylated compounds and metal ions in the flow path in the S-S column was stronger than that between them and the GL-PE column. Thus, the metal ions in the flow path in GL-PE column were low. Since the specific surface area of a pair of frits was 70 times larger than that of a chromatographic tube (150 mm×2.1 mm), the frits were found to have more effective improvement of the S/N as well as the intensity than the chromatographic tubes, when phosphorylated compounds were analyzed by LC-MS. When the evaluated phosphorylated compounds were analyzed by LC-MS(/MS) using a GL-PE column, the intensity and S/N were increased.

  4. Quantification of amino acid ionic liquids using liquid chromatography-mass spectrometry.

    PubMed

    Tang, Fei; Wu, Kangkang; Nie, Zhou; Ding, Li; Liu, Qian; Yuan, Jinbin; Guo, Manli; Yao, Shouzhuo

    2008-10-24

    Amino acid ionic liquids (AAILs) containing imidazolium cations and amino acid (AA) anions, were synthesized and applied as task-specific ionic liquids. A sensitive and fast liquid chromatography-mass spectrometry (LC-MS) method was established for the quantitative analysis of 20 AAILs. Using ion pairing-reversed phase liquid chromatography technique, heptafluorobutyric acid was used as ion-pairing reagent to increase the retention of AAILs. Based on the zwitterionity of amino acid, this method was proposed to determine both the cation and the anion of AAILs simultaneously. The limit of detection of this method is down to 1-15ng/mL and the analysis time is less than 15min. According to the analytical data of seven selected AAILs, we found that the content of amino acid anion is always lower than that of butyl methyl imidazolium cation in AAILs. Moreover, the molar ratio of imidazolium cation to amino acid anion is dependent on the chemical property of the amino acid. These results supplied useful information on the interaction of imidazolium cation with acidic, basic, neutral and non-polar amino acids in AAILs.

  5. Determination of pesticides in soil by liquid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Hou, Li; Lee, Hian Kee

    2004-06-04

    Trace amounts of pesticides in soil were determined by liquid-phase microextraction (LPME) coupled to gas chromatography-mass spectrometry (GC-MS). The technique involved the use of a small amount (3 microl) of organic solvent impregnated in a hollow fiber membrane, which was attached to the needle of a conventional GC syringe. The organic solvent was repeatedly discharged into and withdrawn from the porous polypropylene hollow fiber by a syringe pump, with the pesticides being extracted from a 4 ml aqueous soil sample into the organic solvent within the hollow fiber. Aspects of the developed procedure such as organic solvent selection, extraction time, movement pattern of plunger, concentrations of humic acid and salt, and the proportion of organic solvent in the soil sample, were optimized. Limits of detection (LOD) were between 0.05 and 0.1 microg/g with GC-MS analysis under selected-ion monitoring (SIM). Also, this method provided good precision ranging from 6 to 13%; the relative standard deviations were lower than 10% for most target pesticides (at spiked levels of 0.5 microg/g in aqueous soil sample). Finally, the results were compared to those achieved using solid-phase microextraction (SPME). The results demonstrated that LPME was a fast (within 4 min) and accurate method to determine trace amounts of pesticides in soil.

  6. Postmortem interval estimation: a novel approach utilizing gas chromatography/mass spectrometry-based biochemical profiling.

    PubMed

    Kaszynski, Richard H; Nishiumi, Shin; Azuma, Takeshi; Yoshida, Masaru; Kondo, Takeshi; Takahashi, Motonori; Asano, Migiwa; Ueno, Yasuhiro

    2016-05-01

    While the molecular mechanisms underlying postmortem change have been exhaustively investigated, the establishment of an objective and reliable means for estimating postmortem interval (PMI) remains an elusive feat. In the present study, we exploit low molecular weight metabolites to estimate postmortem interval in mice. After sacrifice, serum and muscle samples were procured from C57BL/6J mice (n = 52) at seven predetermined postmortem intervals (0, 1, 3, 6, 12, 24, and 48 h). After extraction and isolation, low molecular weight metabolites were measured via gas chromatography/mass spectrometry (GC/MS) and examined via semi-quantification studies. Then, PMI prediction models were generated for each of the 175 and 163 metabolites identified in muscle and serum, respectively, using a non-linear least squares curve fitting program. A PMI estimation panel for muscle and serum was then erected which consisted of 17 (9.7%) and 14 (8.5%) of the best PMI biomarkers identified in muscle and serum profiles demonstrating statistically significant correlations between metabolite quantity and PMI. Using a single-blinded assessment, we carried out validation studies on the PMI estimation panels. Mean ± standard deviation for accuracy of muscle and serum PMI prediction panels was -0.27 ± 2.88 and -0.89 ± 2.31 h, respectively. Ultimately, these studies elucidate the utility of metabolomic profiling in PMI estimation and pave the path toward biochemical profiling studies involving human samples.

  7. Determination of Synthetic Cathinones in Urine Using Gas Chromatography-Mass Spectrometry Techniques.

    PubMed

    Hong, Wei-Yin; Ko, Ya-Chun; Lin, Mei-Chih; Wang, Po-Yu; Chen, Yu-Pen; Chiueh, Lih-Ching; Shih, Daniel Yang-Chih; Chou, Hsiu-Kuan; Cheng, Hwei-Fang

    2016-01-01

    In recent years, the abuse of synthetic cathinones has increased considerably. This study proposes a method, based on gas chromatography/mass spectrometry (GC-MS), to analyze and quantify six synthetic cathinones in urine samples: mephedrone (4-MMC), methylone (bk-MDMA), butylone, ethylone, pentylone and methylenedioxypyrovalerone (MDPV). In our procedure, the urine samples undergo solid-phase extraction (SPE) and derivatization prior to injection into the GC-MS device. Separation is performed using a HP-5MS capillary column. The use of selective ion monitoring (SIM mode) makes it is good sensitivity in this method, and the entire analysis process is within 18 min. In addition, the proposed method maintains linearity in the calibration curve from 50 to 2,000 ng/mL (r(2) > 0.995). The limit of detection of this method is 5 ng/mL, with the exception of MDPV (20 ng/mL); the limit of quantification is 20 ng/mL, with the exception of MDPV (50 ng/mL). In testing, the extraction performance of SPE was between 82.34 and 104.46%. Precision and accuracy results were satisfactory <15%. The proposed method was applied to six real urine samples, one of which was found to contain 4-MMC and bk-MDMA. Our results demonstrate the efficacy of the proposed method in the identification of synthetic cathinones in urine, with regard to the limits of detection and quantification. This method is highly repeatable and accurate.

  8. Characterization by gas chromatography/mass spectrometry of sterols in saccharomyces cerevisiae during autolysis.

    PubMed

    Le Fur, Y; Maume, G; Feuillat, M; Maume, B F

    1999-07-01

    Yeast autolysis affects membrane stability and induces a release of vacuolar enzymes into the cell cytoplasm. Consecutively, it was important to study the evolution of sterol content in Saccharomycescerevisiae for a fourteen day period of accelerated autolysis. Unesterified and esterified sterols were analyzed both in the biomass and in the autolysis medium. Ten sterols were identified by gas chromatography/mass spectrometry. A second group of six sterols was separated and partially characterized. Among the first group of 10 sterols, a dehydroergosterol was identified as ergosta-5, 7,9(11),22-tetraen-3beta-ol, not yet charaterized in S. cerevisiae. Yeast autolysis induced a decrease of esterified sterol content, especially first intermediates in the sequence of the ergosterol biosynthesis, as zymosterol. In contrast, the yeast autolysis resulted in the release of a low quantity of sterols into the medium. At the end of the fourteenth day of autolysis, 0.015% of the total sterol content of the initial biomass was found in the medium.

  9. Comprehensive analysis of lipids in biological systems by liquid chromatography-mass spectrometry

    PubMed Central

    2014-01-01

    Liquid chromatography-mass spectrometry (LC-MS)-based lipidomics has been a subject of dramatic developments over the past decade. This review focuses on state of the art in LC-MS-based lipidomics, covering all the steps of global lipidomic profiling. On the basis of review of 185 original papers and application notes, we can conclude that typical LC-MS-based lipidomics methods involve: (1) extraction using chloroform/MeOH or MTBE/MeOH protocols, both with addition of internal standards covering each lipid class; (2) separation of lipids using short microbore columns with sub-2-μm or 2.6–2.8-μm (fused-core) particle size with C18 or C8 sorbent with analysis time <30 min; (3) electrospray ionization in positive- and negative-ion modes with full spectra acquisition using high-resolution MS with capability to MS/MS. Phospholipids (phosphatidylcholines, phosphatidylethanolamines, phosphatidylinositols, phosphatidylserines, phosphatidylglycerols) followed by sphingomyelins, di- and tri-acylglycerols, and ceramides were the most frequently targeted lipid species. PMID:25309011

  10. A novel method for the determination of guanfacine in urine by gas chromatography-mass spectrometry.

    PubMed

    Haglock, Carrie; Wolf, Carl; Poklis, Alphonse

    2008-10-01

    Guanfacine (Tenex), an antihypertensive available since 1975, has recently been indicated for the treatment of attention deficit hyperactivity disorder in children (Intuniv). Because of this new usage, a gas chromatography-mass spectrometry method was developed and validated for the determination of guanfacine in urine. Guanfacine and 100 ng of protriptyline (internal standard) were extracted from 1.0 mL urine with 0.5 mL of saturated carbonate/bicarbonate buffer and 2 mL of ethyl acetate. The solvent extract was evaporated and derivatized with heptaflurobutyric anhydride in n-butyl chloride. Chromatographic separation was achieved using a DB-5 capillary column (30 m x 0.32 mm, 0.25 microm). Ions monitored for guanfacine were m/z 86.1, 272.1, and 274.1, and ions monitored for protriptyline were m/z 191.1 and 189.1. Concentrations were determined using calibrators over the range of 0.1-2.0 mg/L. The linear regression for all calibration curves had r2 values > or = 0.99. The limit of detection was 0.05 mg/L; limit of quantitation was 0.1 mg/L; and upper limit of linearity was 10.0 mg/L. Percent recovery of guanfacine at 0.1 and 2.0 mg/L was 93% and 71%, respectively. The method was found acceptable for routine quantitative analysis of guanfacine in urine.

  11. Determination of phthalate esters in teas and tea infusions by gas chromatography-mass spectrometry.

    PubMed

    Du, Liping; Ma, Lijuan; Qiao, Yang; Lu, Yan; Xiao, Dongguang

    2016-04-15

    Phthalate esters (PAEs), a group of environmental pollutants which are carcinogenic to human body, have been detected in teas. In this work, five PAEs in teas and tea infusions were quantitatively determined by a modified simultaneous distillation extraction (SDE) coupled with gas chromatography-mass spectrometry. After the optimization of SDE, the proposed method afforded a wide range of linearity and high linear regression coefficients with the limits of detection range of 0.24-3.72 μg/kg. The average recoveries were 79.83-116.67% for tea samples and 78.22-101.64% for tea infusions with all the relative standard deviations below 20%. The total content of five PAEs in teas was 1.135-3.734 mg/kg and the total dissolving ratio of five PAEs from tea to infusion was 19.05-28.07% for the selected tea samples. The risk assessment result of all the selected tea samples demonstrated that the population with the habit of drinking tea won't cause risk to human health.

  12. Quantification of busulfan in plasma by gas chromatography-mass spectrometry following derivatization with tetrafluorothiophenol.

    PubMed

    Quernin, M H; Poonkuzhali, B; Montes, C; Krishnamoorthy, R; Dennison, D; Srivastava, A; Vilmer, E; Chandy, M; Jacqz-Aigrain, E

    1998-05-08

    A specific and highly sensitive method has been developed for the determination of busulfan in plasma by gas chromatography-mass spectrometry using a deuterium-labeled busulfan (busulfan-d8) as internal standard. Plasma containing busulfan and busulfan-d8 were extracted with ethyl acetate and derivatized with 2,3,5,6-tetrafluorothiophenol prior to the monitoring of specific ions. The limit of quantification of the assay was 20 ng/ml and the calibration curve was linear over the range of 10 to 2000 ng/ml of derivatized busulfan. This method was in good agreement with the GC-MS assay using derivatization with sodium iodide and measuring diiodobutane. In addition, a pharmacokinetic study of busulfan was conducted in six children. The apparent oral clearance was 5.7+/-1.9 ml/kg/min and the volume of distribution was 1.0+/-0.4 l/kg and were similar to those previously reported in pediatric patients.

  13. Discriminating Hodgdon Pyrodex(®) and Triple Seven(®) using gas chromatography-mass spectrometry.

    PubMed

    Routon, Benjamin J; Kocher, Brandon B; Goodpaster, John V

    2011-01-01

    Pyrodex(®) and Triple Seven(®) are black powder substitutes that often find use as fillers in improvised explosive devices, such as pipe bombs. These propellants have essentially the same overall appearance and oxidizers, but different fuels. For example, Pyrodex(®) contains sulfur, sodium benzoate, and dicyandiamide (DCDA), whereas Triple Seven(®) lacks sulfur but also contains 3-nitrobenzoic acid. In this method, intact particles and postblast solid residues were reacted with bis(trimethylsilyl)trifluoroacetamide + 1% trimethylchlorosilane in acetonitrile for 30 min at 60°C. The resultant trimethylsilyl derivatives of the organic fuels were then analyzed by gas chromatography-mass spectrometry. Each derivative was clearly resolved from other components, and high-quality mass spectra were obtained. In addition, characteristic fragments resulting from loss of a methyl radical from the molecular ion (m/z 163 for sulfur, m/z 171 for DCDA, m/z 179 for benzoic acid, and m/z 224 for nitrobenzoic acid) were able to be monitored.

  14. Enantiomeric determination of DOPA in dietary supplements containing Mucuna pruriens by liquid chromatography/mass spectrometry.

    PubMed

    Hasegawa, Takashi; Takahashi, Kazunaga; Fukiwake, Tomohide; Saijo, Masaaki; Motoki, Yuji

    2013-01-01

    We developed a simple and rapid liquid chromatography/mass spectrometry (LC/MS) method for the enantiomeric determination of DOPA in dietary supplements containing Mucuna pruriens. L- and D-DOPA were ultrasonically extracted with 1% formic acid aqueous solution. The isolated extracts were analyzed by LC/MS using a Crownpak CR (-) column at 30℃. The mass spectrometer was operated in the positive mode of electrospray ionization, and the mobile phase was aqueous formic acid (pH 2.0). L-DOPA-ring-d3 was used as an internal standard. The method was validated for a dietary supplement spiked with L- and D-DOPA at 50 and 500 μg/g, respectively, and the recoveries of the DOPA enantiomers were between 97.5% and 101.3%. Relative standard deviation values of repeatability and intermediate precision were less than 7%. The method was applied to 14 dietary supplements. L-DOPA was detected in these supplements in the range of 0.88-12.8 mg/unit. D-DOPA was not detected.

  15. Flow modulation comprehensive two-dimensional gas chromatography-mass spectrometry with a supersonic molecular beam.

    PubMed

    Kochman, Maya; Gordin, Alexander; Alon, Tal; Amirav, Aviv

    2006-09-29

    A new approach of flow modulation comprehensive two-dimensional gas chromatography-mass spectrometry (GC x GC-MS) with supersonic molecular beam (SMB) and a quadrupole mass analyzer is presented. Flow modulation uniquely enables GC x GC-MS to be achieved even with the limited scan speed of quadrupole MS, and its 20 ml/min column flow rate is handled, splitless, by the SMB interface. Flow modulation GC x GC-SMB-MS shares all the major benefits of GC x GC and combines them with GC-MS including: (a) increased GC separation capability; (b) improved sensitivity via narrower GC peaks; (c) improved sensitivity through reduced matrix interference and chemical noise; (d) polarity and functional group sample information via the order of elution from the second polar column. In addition, GC x GC-SMB-MS is uniquely characterized by the features of GC-MS with SMB of enhanced and trustworthy molecular ion plus isotope abundance analysis (IAA) for improved sample identification and fast fly-through ion source response time. The combination of flow modulation GC x GC with GC-MS with SMB (supersonic GC-MS) was explored with complex matrices such as diesel fuel analysis and pesticide analysis in agricultural products.

  16. Characterization of ballpoint pen inks by thermal and desorption and gas chromatography-mass spectrometry.

    PubMed

    Bügler, Jürgen H; Buchner, Hans; Dallmayer, Anton

    2005-09-01

    The characterization of ink on paper is of importance for dating and comparing questioned ink entries in forensic document examination. Inks are commonly characterized by their colorant profile that is identified by well-established analytical methods. Numerous ink formulations show identical colorant profiles, though. In order to differentiate inks that are not distinguishable by colorant analysis, a method for the characterization of colorless ink ingredients, namely binders, solvents and additives is necessary. In this paper, we propose a technique for the analysis of colorless compounds in ballpoint inks using direct thermal desorption of the ink on paper followed by chemical analysis of the desorbed volatile compounds by gas chromatography-mass spectrometry. As compared to liquid extraction and subsequent analysis of the extracts, the technique avoids possible contamination risks. Sensitivity is very high due to the enrichment of volatile components by thermal desorption. Even from old samples, the chromatograms obtained by the method enable the determination of binder polymers, solvents and additives. Pure binders as used by ink manufacturers were analyzed for unambiguous assignment of analytical results to specific polymers. To prove the practical applicability, we analyzed 121 ballpoint pens, not all having the same colorant profile, and grouped the pens into resin and solvent categories.

  17. The gas chromatography/mass spectrometry can be used for dose estimation in irradiated pork

    NASA Astrophysics Data System (ADS)

    D'Oca, M. C.; Bartolotta, A.; Cammilleri, M. C.; Giuffrida, S. A.; Parlato, A.; Di Noto, A. M.; Caracappa, S.

    2009-07-01

    Food safety can be improved using ionizing radiation to reduce food spoilage and to extend its shelf life. The gas chromatography/mass spectrometry (GC/MS) has been validated by the European Community as a powerful method to identify irradiated food containing fat. The preliminary goals of our research were: (i) to set up this method, based on the detection of radiation induced 2-dodecylcyclobutanones (2-DCB) in pork muscle samples and (ii) to check the microbiological efficacy of the treatment. The main objective was to render the GC/MS a quantitative technique for dose estimation, through the measurement of the 2-DCB concentration in the irradiated sample. Our results show that the reduction of the microbial population is substantially reduced even at 2 kGy, and that a clear identification of irradiated samples can be achieved also one month after irradiation at 2 kGy in frozen-stored samples. The 2-DCB concentration showed a linear dependence on dose in the range 1-10 kGy, no matter the origin of the sample; a unique calibration function was obtained, that allowed dose estimation in irradiated pork samples. A retrospective evaluation on the quality of the treatment could be carried out this way.

  18. Relative quantitation of transfer RNAs using liquid chromatography mass spectrometry and signature digestion products.

    PubMed

    Castleberry, Colette M; Limbach, Patrick A

    2010-09-01

    Transfer ribonucleic acids (tRNAs) are challenging to identify and quantify from unseparated mixtures. Our lab previously developed the signature digestion approach for identifying tRNAs without specific separation. Here we describe the combination of relative quantification via enzyme-mediated isotope labeling with this signature digestion approach for the relative quantification of tRNAs. These quantitative signature digestion products were characterized using liquid chromatography mass spectrometry (LC-MS), and we find that up to 5-fold changes in tRNA abundance can be quantified from sub-microgram amounts of total tRNA. Quantitative tRNA signature digestion products must (i) incorporate an isotopic label during enzymatic digestion; (ii) have no m/z interferences from other signature digestion products in the sample and (iii) yield a linear response during LC-MS analysis. Under these experimental conditions, the RNase T1, A and U2 signature digestion products that potentially could be used for the relative quantification of Escherichia coli tRNAs were identified, and the linearity and sequence identify of RNase T1 signature digestion products were experimentally confirmed. These RNase T1 quantitative signature digestion products were then used in proof-of-principle experiments to quantify changes arising due to different culturing media to 17 tRNA families. This method enables new experiments where information regarding tRNA identity and changes in abundance are desired.

  19. Metabolomic profiling reveals potential biomarkers in esophageal cancer progression using liquid chromatography-mass spectrometry platform.

    PubMed

    Zhang, Haiping; Wang, Lei; Hou, Zhichao; Ma, Hong; Mamtimin, Batur; Hasim, Ayshamgul; Sheyhidin, Ilyar

    2017-09-09

    Esophageal cancer (EC) is one of the most common malignancies with poor prognosis. Metabolomics has been shown to be a powerful approach to discover the potential biomarkers for cancer diagnosis and prognosis. The goal of this study is to screen potential biomarkers for early diagnosis and prognosis. In this study, 40 tissue samples and the corresponding control samples from the same esophageal squamous cell carcinoma (ESCC) patients were analyzed by liquid chromatography-mass spectrometry (LC-MS)-based metabolomics. 20 potential diagnostic biomarkers were selected. Moreover, 9 metabolites were found to be closely correlated with the pathological feature such as local invasion, lymphatic metastasis and postoperative survival time. Glutamate was correlated with local invasion of tumor, and oleic acid, LysoPC(15:0), uracil, inosine and choline were closely related with the lymphatic metastasis, while glutamine, kynurenine, serine and uracil were related with postoperative survival time. The results indicated that the potential biomarkers discovered by metabolomics could reflect the metabolic characterization of ESCC, and offers a novel approach for early diagnosis, assessment and prognosis of the disease. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Serum total testosterone: immunoassay compared with negative chemical ionization gas chromatography-mass spectrometry.

    PubMed

    Fitzgerald, R L; Herold, D A

    1996-05-01

    We have developed an electron capture negative chemical ionization gas chromatography-mass spectrometry (GC-MS) procedure to quantify serum testosterone in the clinically relevant range 0.69-69.3 nmol/L and used this procedure to assess Ciba Corning Diagnostics ACS:180 testosterone immunoassay. The GC-MS method involves liquid-liquid extraction of serum samples and synthesis of a pentafluorobenzyloxime/silyl ether derivative of testosterone with excellent chromatographic and electron capturing properties. The ACS testosterone assay is the first fully automated nonradioactive testosterone immunoassay approved by the US Food and Drug Administration. Patients' specimens (101, 57 males, 44 females) were analyzed by both techniques. A plot of the GC-MS (x) vs ACS (y) testosterone concentrations for men was linear (y = 1.07x + 0.19 nmol/L), showing excellent correlation (r2 = 0.98) between the two assays. Agreement of the two assays for female specimens was poor (y = 0.72x + 1.2 nmol/L), with a poor correlation (r2 = 0.31).

  1. A Liquid Chromatography/Mass Spectrometry Method for Screening Disulfide Tethering Fragments.

    PubMed

    Hallenbeck, Kenneth K; Davies, Julia L; Merron, Connie; Ogden, Pierce; Sijbesma, Eline; Ottmann, Christian; Renslo, Adam R; Wilson, Christopher; Arkin, Michelle R

    2017-09-01

    We report the refinement of a high-throughput, liquid chromatography/mass spectrometry (LC/MS)-based screening method for the identification of covalent small-molecule binders to proteins. Using a custom library of 1600 disulfide-capped fragments targeting surface cysteine residues, we optimize sample preparation, chromatography, and ionization conditions to maximize the reliability and flexibility of the approach. Data collection at a rate of 84 s per sample balances speed with reliability for sustained screening over multiple, diverse projects run over a 24-month period. The method is applicable to protein targets of various classes and a range of molecular masses. Data are processed in a custom pipeline that calculates a percent bound value for each compound and identifies false positives by calculating significance of detected masses (signal significance). An example pipeline is available through Biovia's ScienceCloud Protocol Exchange. Data collection and analysis methods for the screening of covalent adducts of intact proteins are now fast enough to screen the largest covalent compound libraries in 1 to 2 days.

  2. Determination of ortho-phenylphenol in human urine by gas chromatography-mass spectrometry.

    PubMed

    Bartels, M J; Brzak, K A; Bormett, G A

    1997-12-05

    A sensitive gas chromatographic-mass spectrometric method was developed to quantitate total o-phenylphenol (OPP) (free plus conjugates) in human urine. Conjugates of OPP were acid-hydrolyzed to free OPP, derivatized to the pentafluorobenzoyl ester derivative and analyzed via negative-ion chemical ionization gas chromatography-mass spectrometry. Two stable isotope analogs of OPP were shown to be suitable as internal standards for this method (D2-phenol ring, 13C6-phenyl ring). A synthetic method is presented for the preparation of the D2-OPP internal standard. The 13C6-OPP analog was also shown to be useful as an alternate test material for laboratory-based exposure studies. The limit of quantitation for this method was 1 ng OPP/ml urine. Calibration curves were linear for the analyte over the concentration range of 0.5-1117 ng OPP/ml urine. Relative recovery of OPP from urine ranged from 97.0 to 104.7%. Low levels of OPP (mean=6+/-7 ng/ml; n=22) were found in control human urine samples. The method was validated with urine samples obtained from human volunteers undergoing a dermal exposure study with 12C-/13C6-/14C-OPP. This method was developed to aid in assessments of human exposure to OPP during a variety of uses of the compound.

  3. Gas chromatography-mass spectrometry determination of phosphine residues in stored products and processed foods.

    PubMed

    Norman, K N; Leonard, K

    2000-09-01

    A gas chromatography-mass spectrometry (GC-MS) method was used for the quantitative confirmation of phosphine residues in stored products and processed foods. An established extraction technique was utilized for the preparation of headspace samples, which were analyzed by GC-MS and gas chromatography-nitrogen-phosphorus detection (GC-NPD). Wheat, oats, maize, white rice, brown rice, cornflakes, tortilla cornchips, groundnuts, and raisins were validated, showing excellent agreement between detectors when spiked at levels equivalent to 0.001 and 0.01 mg/kg phosphine and for samples containing incurred residues. The GC-MS method was reproducible and accurate when compared to the GC-NPD method and allowed five samples to be quantified in a working day. Subambient GC-MS oven temperatures were most suitable for phosphine residues ranging from 0.001 to 0.005 mg/kg, and a GC oven temperature of 100 degrees C was appropriate for residues >0.005 mg/kg. The method was sufficiently robust to be evaluated for other similar commodities as the need arises.

  4. Identification of tartary buckwheat tea aroma compounds with gas chromatography-mass spectrometry.

    PubMed

    Qin, Peiyou; Ma, Tingjun; Wu, Li; Shan, Fang; Ren, Guixing

    2011-08-01

    Tartary buckwheat tea, which is an important and healthy product, has a distinct malty aroma. However, its characteristic aroma compounds have not been elucidated. The aims of present study were identification and quantification of its aroma compounds. The analyses were performed by gas chromatography-mass spectrometry (GC-MS) after 3 different isolation techniques. Seventy-seven compounds were identified. Among these compounds, 35 were quantified by available standards. The compounds with a high probability of contribution to the tartary buckwheat tea aroma (OAV ≥ 10) were as follows: 2,5-dimethyl-4-hydroxy-3(2H)-furanone, nonanal, 2,3-diethyl-5-methylpyrazine, benzeneacetaldehyde, maltol, 2,5-dimethylpyrazine, 2-ethyl-5-methylpyrazine, trimethylpyrazine. Some nutritional and bioactive compounds were also identified in this study, such as linoleic acid, niacin, vanillic acid, 7-hydroxycoumarin, butylated hydroxytoluene. Practical Application: Tartary buckwheat, one type of buckwheat, has gained much attention from nutritionists and medical doctors in recent years. It is rich in rutin, quercetin, and other nutrients that are good for health. Tartary buckwheat-based product such as tartary buckwheat tea is an important and popular healthy product in China, Japan,South Korea, European countries as well as in American countries. It has a distinct malty aroma. The present study first identified and quantified of its aroma compounds. The results will draw attention to other researchers in food flavor and buckwheat filed.

  5. Integration of gas chromatography mass spectrometry methods for differentiating ricin preparation methods.

    PubMed

    Wunschel, David S; Melville, Angela M; Ehrhardt, Christopher J; Colburn, Heather A; Victry, Kristin D; Antolick, Kathryn C; Wahl, Jon H; Wahl, Karen L

    2012-05-07

    The investigation of crimes involving chemical or biological agents is infrequent, but presents unique analytical challenges. The protein toxin ricin is encountered more frequently than other agents and is found in the seeds of Ricinus communis, commonly known as the castor plant. Typically, the toxin is extracted from castor seeds utilizing a variety of different recipes that result in varying purity of the toxin. Moreover, these various purification steps can also leave or differentially remove a variety of exogenous and endogenous residual components with the toxin that may indicate the type and number of purification steps involved. We have applied three gas chromatography-mass spectrometry (GC-MS) based analytical methods to measure the variation in seed carbohydrates and castor oil ricinoleic acid, as well as the presence of solvents used for purification. These methods were applied to the same samples prepared using four previously identified toxin preparation methods, starting from four varieties of castor seeds. The individual data sets for seed carbohydrate profiles, ricinoleic acid, or acetone amount each provided information capable of differentiating different types of toxin preparations across seed types. However, the integration of the data sets using multivariate factor analysis provided a clear distinction of all samples based on the preparation method, independent of the seed source. In particular, the abundance of mannose, arabinose, fucose, ricinoleic acid, and acetone were shown to be important differentiating factors. These complementary tools provide a more confident determination of the method of toxin preparation than would be possible using a single analytical method.

  6. [Determination of two mouldy compounds in cork by gas chromatography-mass spectrometry].

    PubMed

    Tang, Xi; Liang, Ming; Li, Xiaojing; Xiong, Wenming; Tang, Hong; Jiang, Xiaoli; Chen, Jiamin

    2012-07-01

    A simple and fast method for the simultaneous determination of two mouldy compounds, 2,4,6-trichloroanisole (TCA) and 2,4,6-tribromoanisole (TBA), in cork by gas chromatography-mass spectrometry (GC-MS) was established. The analytes were extracted by ultrasonic extraction with methanol, and purified then by solid phase extraction using primary secondary amine (PSA) as solid phase. After concentrating, the sample was analyzed by GC-MS and quantified by the external standard method. The linear ranges were from 10 microg/L to 10 000 microg/L for TCA and TBA, the correlation coefficients (r2) of the calibration curves were above 0.99. The recoveries and the relative standard deviations (RSDs) of TCA and TBA in different kinds of corks were investigated. The recoveries ranged from 88.4% to 97.6% with the RSDs between 1.02% and 4.58% (n = 6). The limits of detection (LODs) were 12 microg/L for TCA and 18 microg/L for TBA, and the limits of quantification (LOQs) were 40 microg/L for TCA and 50 microg/L for TBA. The method is suitable to the determination of TCA and TBA in corks.

  7. Thermal degradation of α-pyrrolidinopentiophenone during injection in gas chromatography/mass spectrometry.

    PubMed

    Tsujikawa, Kenji; Kuwayama, Kenji; Kanamori, Tatsuyuki; Iwata, Yuko T; Inoue, Hiroyuki

    2013-09-10

    α-Pyrrolidinopentiophenone (α-PVP) is a popular recreational drug in Japan. This drug easily undergoes thermal decomposition during gas chromatography/mass spectrometry analysis. We evaluated three factors involved in the decomposition, namely the injection method (splitless or split, split ratio), injector temperature, and surface activity on the inlet liner. Splitless injection of α-PVP using a used deactivated split/splitless liner at an injector temperature of 250 °C caused thermal decomposition. This decomposition was inhibited by split injection. A higher split ratio resulted in greater prevention. Based on the mass spectrum of deuterated α-PVP, the decomposition product was presumed to be an enamine whose double bond was located in the alkyl chain. Lowering the injection temperature from 250 °C to 200 °C did not prevent decomposition. New glass liners, both deactivated and non-deactivated, were compared. The use of a new deactivated liner minimized thermal decomposition, even for splitless injection, while the non-deactivated liner generated an increase in the amount of the decomposition product. These results showed that the injection method and the surface activity on the inlet liner were involved in the thermal decomposition of α-PVP.

  8. Optimizing 2D gas chromatography mass spectrometry for robust tissue, serum and urine metabolite profiling.

    PubMed

    Yu, Zhanru; Huang, Honglei; Reim, Alexander; Charles, Philip D; Northage, Alan; Jackson, Dianne; Parry, Ian; Kessler, Benedikt M

    2017-04-01

    Two-dimensional gas chromatography mass spectrometry (GCxGC-MS) is utilized to an increasing extent in biomedical metabolomics. Here, we established and adapted metabolite extraction and derivatization protocols for cell/tissue biopsy, serum and urine samples according to their individual properties. GCxGC-MS analysis revealed detection of ~600 molecular features from which 165 were characterized representing different classes such as amino acids, fatty acids, lipids, carbohydrates, nucleotides and small polar components of glycolysis and the Krebs cycle using electron impact (EI) spectrum matching and validation using external standard compounds. Advantages of two-dimensional gas chromatography based resolution were demonstrated by optimizing gradient length and separation through modulation between the first and second column, leading to a marked increase in metabolite identification due to improved separation as exemplified for lactate versus pyruvate, talopyranose versus methyl palmitate and inosine versus docosahexaenoic acid. Our results demonstrate that GCxGC-MS represents a robust metabolomics platform for discovery and targeted studies that can be used with samples derived from the clinic. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  9. Chemical discrimination in turbulent gas mixtures with MOX sensors validated by gas chromatography-mass spectrometry.

    PubMed

    Fonollosa, Jordi; Rodríguez-Luján, Irene; Trincavelli, Marco; Vergara, Alexander; Huerta, Ramón

    2014-10-16

    Chemical detection systems based on chemo-resistive sensors usually include a gas chamber to control the sample air flow and to minimize turbulence. However, such a kind of experimental setup does not reproduce the gas concentration fluctuations observed in natural environments and destroys the spatio-temporal information contained in gas plumes. Aiming at reproducing more realistic environments, we utilize a wind tunnel with two independent gas sources that get naturally mixed along a turbulent flow. For the first time, chemo-resistive gas sensors are exposed to dynamic gas mixtures generated with several concentration levels at the sources. Moreover, the ground truth of gas concentrations at the sensor location was estimated by means of gas chromatography-mass spectrometry. We used a support vector machine as a tool to show that chemo-resistive transduction can be utilized to reliably identify chemical components in dynamic turbulent mixtures, as long as sufficient gas concentration coverage is used. We show that in open sampling systems, training the classifiers only on high concentrations of gases produces less effective classification and that it is important to calibrate the classification method with data at low gas concentrations to achieve optimal performance.

  10. Oxysterols in cosmetics-Determination by planar solid phase extraction and gas chromatography-mass spectrometry.

    PubMed

    Schrack, S; Hohl, C; Schwack, W

    2016-11-18

    Sterol oxidation products (SOPs) are linked to several toxicological effects. Therefore, investigation of potential dietary uptake sources particularly food of animal origin has been a key issue for these compounds. For the simultaneous determination of oxysterols from cholesterol, phytosterols, dihydrolanosterol and lanosterol in complex cosmetic matrices, planar solid phase extraction (pSPE) was applied as clean-up tool. SOPs were first separated from more non-polar and polar matrix constituents by normal phase thin-layer chromatography and then focussed into one target zone. Zone extraction was performed with the TLC-MS interface, followed by gas chromatography-mass spectrometry analysis. pSPE showed to be effective for cleaning up cosmetic samples as sample extracts were free of interferences, and gas chromatographic columns did not show any signs of overloading. Recoveries were between 86 and 113% with relative standard deviations of below 10% (n=6). Results of our market survey in 2016 showed that some cosmetics with ingredients of plant origin contained phytosterol oxidation products (POPs) in the low ppm range and therefore in line with levels reported for food. In lanolin containing products, total SOPs levels (cholesterol oxidation products (COPs), lanosterol oxidation products (LOPs), dihydrolanosterol oxidation products (DOPs)) being in the low percent range exceeded reported levels for food by several orders of magnitudes. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Determination of Morphine and Codeine in Human Urine by Gas Chromatography-Mass Spectrometry

    PubMed Central

    Zhang, Xiaoqian; Cao, Gaozhong; Hu, Guoxin

    2013-01-01

    A sensitive and selective gas chromatography-mass spectrometry (GC-MS) method was developed and validated for the determination of morphine and codeine in human urine. The GC-MS conditions were developed. The analysis was carried out on a HP-1MS column (30 m × 0.25 mm, 0.25 μm) with temperature programming, and Helium was used as the carrier gas with a flow rate of 1.0 mL/min. Selected ion monitoring (SIM) mode was used to quantify morphine and codeine. The derivation solvent, temperature, and time were optimized. A mixed solvent of propionic anhydride and pyridine (5 : 2) was finally used for the derivation at 80°C for 3 min. Linear calibration curves were obtained in the concentration range of 25–2000.0 ng/mL, with a lower limit of quantification of 25 ng/mL. The intra- and interday precision (RSD) values were below 13%, and the accuracy was in the range 87.2–108.5%. This developed method was successfully used for the determination of morphine and codeine in human urine for forensic identification study. PMID:24222889

  12. A gas chromatography-mass spectrometry method to monitor detergents removal from a membrane protein sample.

    PubMed

    Shi, Chaowei; Han, Fang; Xiong, Ying; Tian, Changlin

    2009-12-01

    In membrane protein biochemical and structural studies, detergents are used to mimic membrane environment and maintain functional, stable conformation of membrane proteins in the absence of lipid bilayers. However, detergent concentration, esp. molar ratio of membrane protein to detergent is usually unknown. Here, a gas chromatography-mass spectrometry selected ion monitoring (GC-MS-SIM) method was developed to quantify four detergents which are frequently used in membrane protein structural studies. To remove excessive detergents, a filtered centrifugation using Centricon tubes was applied. A membrane protein Ig-Beta fragment in four different detergent micelles was exemplified. Detergent concentrations in the upper and lower fraction of the Centricon tube were measured after each round of centrifugation. The results were very consistent to basic properties of detergent micelles in aqueous solvents. Therefore, coupling of GC-MS-SIM and detergent removal by Centricon tubes, detergents concentration, esp. molar ratio of membrane protein to detergent could be controlled, which will expedite membrane protein structural and biochemical studies.

  13. Determination of terpenes in tequila by solid phase microextraction-gas chromatography-mass spectrometry.

    PubMed

    Peña-Alvarez, Araceli; Capella, Santiago; Juárez, Rocío; Labastida, Carmen

    2006-11-17

    Solid phase microextraction and capillary gas chromatography-mass spectrometry were used for the determination of seven terpenes in tequila. The method was selected based on the following parameters: coating selection (PA, PDMS, CW/DVB, and PDMS/DVB), extraction temperature, addition of salt, and extraction time profile. The extraction conditions were: PDMS/DVB fiber, Headspace, 100% NaCl, 25 degrees C extraction temperature, 30 min extraction time and stirring at 1200 rpm. The calibration curves (50-1000 ng/ml) for the terpenes followed linear relationships with correlation coefficients (r) greater than 0.99, except for trans,trans-farnesol (r = 0.98). RSD values were smaller than 10% confirmed that the technique was precise. Samples from 18 different trade brands of "Aged" tequila analyzed with the developed method showed the same terpenes in different concentrations. The analytical procedure used is selective, robust (more than 100 analyses with the same fiber), fast and of low-cost.

  14. Urinary Succinylacetone Analysis by Gas Chromatography-Mass Spectrometry (GC-MS).

    PubMed

    Chen, Hongjie; Yu, Chunli

    2016-01-01

    Succinylacetone (SA) is used for the diagnosis and monitoring of patients with tyrosinemia type I (Tyr I). SA is exclusively elevated in blood and urine of patients with Tyr I. As urinary SA concentration is much higher than blood, SA is usually tested in urine samples. Urinary SA quantitation by gas chromatography mass spectrometry (GC-MS) is described in this chapter. The urine sample in the amount of 1 μmol creatinine is used for testing. 3,4,5,6,7-(13)C5-succinylacetone ((13)C5-SA) is used as an internal standard (IS). SA and (13)C5-SA are oximated and extracted from urine with organic solvents, and then derivatized to form trimethylsilane (TMS) derivatives. TMS derivatives of SA and (13)C5-SA are detected and quantified by GC-MS using selective ion monitoring (SIM). The assay is linear from 0.05 to 450 mmol/mol creatinine to cover the broad range of urinary SA concentrations.

  15. Fingerprint developing of coffee flavor by gas chromatography-mass spectrometry and combined chemometrics methods.

    PubMed

    Huang, Lan-Fang; Wu, Ming-Jian; Zhong, Ke-Jun; Sun, Xian-Jun; Liang, Yi-Zeng; Dai, Yun-Hui; Huang, Ke-Long; Guo, Fang-Qiu

    2007-04-11

    In this paper, chromatographic fingerprint was firstly used for quality control of tobacco flavors. Based on gas chromatography-mass spectrometry (GC-MS) and combined chemometrics methods, a simple, reliable and reproducible method for developing chromatographic fingerprint of coffee flavor, one of tobacco flavors, was described. Six coffee flavor samples obtained from different locations were used to establish the fingerprint. The qualitative and quantitative analysis of coffee flavor sample from Shenzhen was completed with the help of subwindow factor analysis (SFA). Fifty-two components of 68 separated constituents in coffee flavor sample from Shenzhen, accounting for 88.42% of the total content, were identified and quantified. Then, spectral correlative chromatography (SCC) was used to extract the common peaks from other five studied coffee flavor samples. Thirty-eight components were found to exist in all six samples. Finally, the method validation of fingerprint analysis was performed based on the relative retention time and the relative peak area of common peaks, sample stability and similarity analysis. The similarities of six coffee flavor samples were more than 0.9104 and showed that samples from different locations were consistent to some extent. The developed chromatographic fingerprint was successfully used to differentiate coffee flavor from cocoa flavor and some little difference sample prepared with coffee flavor and cocoa flavor by both similarity comparison and principal component projection analysis. The developed method can be used for quality control of coffee flavor.

  16. Valid internal standard technique for arson detection based on gas chromatography-mass spectrometry.

    PubMed

    Salgueiro, Pedro A S; Borges, Carlos M F; Bettencourt da Silva, Ricardo J N

    2012-09-28

    The most popular procedures for the detection of residues of accelerants in fire debris are the ones published by the American Society for Testing and Materials (ASTM E1412-07 and E1618-10). The most critical stages of these tests are the conservation of fire debris from the sampling to the laboratory, the extraction of residues of accelerants from the debris to the activated charcoal strips (ACS) and from those to the final solvent, as well as the analysis of sample extract by gas chromatography-mass spectrometry (GC-MS) and the interpretation of the instrumental signal. This work proposes a strategy for checking the quality of the sample conservation, the accelerant residues transference to final solvent and GC-MS analysis, using internal standard additions. It is used internal standards ranging from a highly volatile compound for checking debris conservation to low volatile compound for checking GC-MS repeatability. The developed quality control (QC) parameters are not affected by GC-MS sensitivity variation and, specifically, the GC-MS performance control is not affected by ACS adsorption saturation that may mask test performance deviations. The proposed QC procedure proved to be adequate to check GC-MS repeatability, ACS extraction and sample conservation since: (1) standard additions are affected by negligible uncertainty and (2) observed dispersion of QC parameters are fit for its intended use.

  17. Metabolic Profiling and Quantification of Neurotransmitters in Mouse Brain by Gas Chromatography-Mass Spectrometry.

    PubMed

    Jäger, Christian; Hiller, Karsten; Buttini, Manuel

    2016-09-01

    Metabolites are key mediators of cellular functions, and have emerged as important modulators in a variety of diseases. Recent developments in translational biomedicine have highlighted the importance of not looking at just one disease marker or disease inducing molecule, but at populations thereof to gain a global understanding of cellular function in health and disease. The goal of metabolomics is the systematic identification and quantification of metabolite populations. One of the most pressing issues of our times is the understanding of normal and diseased nervous tissue functions. To ensure high quality data, proper sample processing is crucial. Here, we present a method for the extraction of metabolites from brain tissue, their subsequent preparation for non-targeted gas chromatography-mass spectrometry (GC-MS) measurement, as well as giving some guidelines for processing of raw data. In addition, we present a sensitive screening method for neurotransmitters based on GC-MS in selected ion monitoring mode. The precise multi-analyte detection and quantification of amino acid and monoamine neurotransmitters can be used for further studies such as metabolic modeling. Our protocol can be applied to shed light on nervous tissue function in health, as well as neurodegenerative disease mechanisms and the effect of experimental therapeutics at the metabolic level. © 2016 by John Wiley & Sons, Inc.

  18. Microwave-assisted derivatization: application to steroid profiling by gas chromatography/mass spectrometry.

    PubMed

    Casals, Gregori; Marcos, Josep; Pozo, Oscar J; Alcaraz, José; Martínez de Osaba, María Jesús; Jiménez, Wladimiro

    2014-06-01

    Gas chromatography-mass spectrometry (GC-MS) remains as the gold-standard technique for the study of the steroid metabolome. A main limitation is the need of performing a derivatization step since incubation with strong silylations agents for long periods of time (usually 16 h) is required for the derivatization of hindered hydroxyls present in some steroids of interest. In the present work, a rapid, simple and reproducible microwave-assisted derivatization method was developed. In the method, 36 steroids already treated with methoxyamine (2% in pyridine) were silylated with 50 μl of N-trimethylsilylimidazole by using microwave irradiation, and the formed methyloxime-trimethylsilyl derivatives were analyzed by GC-MS. Microwave power and derivatization time silylation conditions were optimized being the optimum conditions 600 W and 3 min respectively. In order to evaluate the usefulness of this technique, the urine steroid profiles for 20 healthy individuals were analyzed. The results of a comparison of microwave irradiation with the classical heating protocol showed similar derivatization yields, thus suggesting that microwave-assisted silylation is a valid tool for the rapid steroid metabolome study.

  19. Measurement of F2- isoprostanes and isofurans using gas chromatography-mass spectrometry.

    PubMed

    Milne, Ginger L; Gao, Benlian; Terry, Erin S; Zackert, William E; Sanchez, Stephanie C

    2013-06-01

    F2-Isoprostanes (IsoPs) are isomers of prostaglandin F2α formed from the nonenzymatic free radical-catalyzed peroxidation of arachidonic acid. Since discovery of these molecules by Morrow and Roberts in 1990, F2-IsoPs have been shown to be excellent biomarkers as well as potent mediators of oxidative stress in vivo in humans. Isofurans (IsoFs) are also oxidation products generated from the nonenzymatic oxidation of arachidonic acid. IsoFs are preferentially formed instead of F2-IsoPs in settings of increased oxygen tension. The protocol presented herein is the current methodology that our laboratory uses to quantify F2-IsoPs and IsoFs in biological tissues and fluids using gas chromatography/mass spectrometry (GC/MS). A variety of analytical procedures to measure F2-IsoPs, including other GC/MS methods and liquid chromatography/MS and immunological approaches, are reported in the literature. This method provides a very low limit of quantitation and is suitable for analysis of both F2-IsoPs and IsoFs from a variety of biological sources including urine, plasma, tissues, cerebral spinal fluid, exhaled breath condensate, and amniotic fluid, among others.

  20. Determination of free and ethoxylated alkylphenols in leather with gas chromatography-mass spectrometry.

    PubMed

    Ma, He-Wei; Cheng, Ya

    2010-12-10

    An analytical approach was developed to determine nonylphenol (NP), octylphenol (OP), nonylphenol ethoxylates (NPEO(n)) and octylphenol ethoxylates (OPEO(n)) in leather samples involving the conversion of NPEO(n) and OPEO(n) into the corresponding NP and OP. The four targets were extracted from samples using ultrasonic-assisted acetonitrile extraction. NP and OP in the extracts were directly isolated with hexane and quantitatively determined with 4-n-nonylphenol as internal standard by gas chromatography-mass spectrometry (GC-MS). For NPEO(n) and OPEO(n) in the extracts, they were first converted into NP and OP with aluminum triiodide as cleavage agent, and the yielded NP and OP were determined by GC-MS. The contents of NPEO(n) and OPEO(n) were calculated by normalizing to NPEO(9) and OPEO(9), respectively. This method was properly validated and the real sample tests revealed the pollution significance of leather by NPEO(n) and OPEO(n).

  1. Determination of methomyl in the stomach contents of baited wildlife by gas chromatography-mass spectrometry.

    PubMed

    Buchweitz, John P; Bokhart, Mark; Johnson, Margaret; Lehner, Andreas

    2013-11-01

    The poisoning of wildlife with fly-bait containing the active ingredient methomyl is an intentional and illegal act in many jurisdictions. A case of 2 animals poisoned by methomyl through consumption of tainted bait at multiple stations is described. Although thermally and ultraviolet-labile, methomyl can be identified by gas chromatography-mass spectrometry and is detected in abundance in bait samples; however, it is not readily observed in tissues, owing to its rapid metabolism and elimination. The application of derivatizing functionalities, such as trimethylsilyl groups, stabilizes the methomyl-oxime metabolite to facilitate its detectability during exposure to the relatively harsh conditions of gas chromatography. This brief communication reports on the analytical detection of methomyl in baits and biological samples from poisoned wildlife. Essential to the case were the added determination of a fly-bait coactive ingredient, (Z)-9-tricosene, and identification of a chemical indicator, caffeine, to confirm both the type of pesticide product involved in the poisoning incident and the vehicle used to perpetrate its delivery.

  2. Solid-phase microextraction gas chromatography-mass spectrometry determination of fragrance allergens in baby bathwater.

    PubMed

    Lamas, J Pablo; Sanchez-Prado, Lucia; Garcia-Jares, Carmen; Llompart, Maria

    2009-07-01

    A method based on solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) has been optimized for the determination of fragrance allergens in water samples. This is the first study devoted to this family of cosmetic ingredients performed by SPME. The influence of parameters such as fibre coating, extraction and desorption temperatures, salting-out effect and sampling mode on the extraction efficiency has been studied by means of a mixed-level factorial design, which allowed the study of the main effects as well as two-factor interactions. Excluding desorption temperature, the other parameters were, in general, very important for the achievement of high response. The final procedure was based on headspace sampling at 100 degrees C, using polydimethylsiloxane/divinylbenzene fibres. The method showed good linearity and precision for all compounds, with detection limits ranging from 0.001 to 0.3 ng mL(-1). Reliability was demonstrated through the evaluation of the recoveries in different real water samples, including baby bathwater and swimming pool water. The absence of matrix effects allowed the use of external standard calibration to quantify the target compounds in the samples. The proposed procedure was applied to the determination of allergens in several real samples. All the target compounds were found in the samples, and, in some cases, at quite high concentrations. The presence and the levels of these chemicals in baby bathwater should be a matter of concern.

  3. Analysis of extractable organic compounds in water by gas chromatography mass spectrometry: applications to surface water.

    PubMed

    Deroux, J M; Gonzalez, C; Le Cloirec, P; Kovacsik, G

    1996-03-01

    Contamination of water by organic pollutants is a common environmental problem. Over a period of 1 year, the surface water of a canal network (Languedoc-Roussillon area, France) was analysed in order to identify organic compounds and to monitor its quality. Pollutants were extracted from 19 l of raw water using methylene chloride in a continuous countercurrent liquid-liquid extractor with a pulsed column. The extraction was performed at a pH above 11 and again at a pH below 2 according to U.S. Environmental Protection Agency method 625. The extract was analysed by gas chromatography/mass spectrometry, using two ionization techniques, namely electron ionization and chemical ionization. Mass spectra obtained by electron ionization were compared with those in a database (NIST). Some natural compounds and micropollutants were identified. Their structures were confirmed by chemical ionization (methane). One hundred and ten substances, making up the broad spectrum of extractable compounds in the surface water studied, were found by this method at a nanogram per litre concentration level. Among them, 13 are priority pollutants. These specific pollutants were qualified.

  4. [Determination of five representative ultraviolet filters in water by gas chromatography-mass spectrometry].

    PubMed

    Ding, Yiran; Huang, Yun; Zhao, Tingting; Cai, Qian; Luo, Yu; Huang, Bin; Zhang, Yuxia; Pan, Xuejun

    2014-06-01

    A method for the determination of five representative organic UV filters: ethylhexyl methoxycinnamate (EHMC), benzophenone-3 (BP-3), 4-methylbenzylidene camphor (4-MBC), octocrylene (OC), homosalate (HMS) in water was investigated. The method was ased on derivatization, solid phase extraction (SPE), followed by determination with gas chromatography-mass spectrometry (GC-MS). The variables involved in the derivatization of BP-3 and HMS were optimized, and SPE conditions were studied. For derivatization, 100 microL N,O-bis(trimethylsilyl) trifluoroacetamide (BSTFA) was used as derivatization reagent and reacted with BP-3 and HMS at 100 degrees C for 100 min. For SPE, the pH value of water sample was adjusted to 3-5. The Oasis HLB cartridges were employed and the solution of ethyl acetate and dichloromethane (1 : 1, v/v) was used as the eluting solvent, and good recoveries of the target compounds were obtained. The limits of detection (LODs) and the limits of quantification (LOQs) for the five target compounds in water samples were 0.5-1.2 ng/L and 1.4-4.0 ng/L, respectively. The recoveries of spiked water samples were 87.85%-102.34% with good repeatability and reproducibility (RSD < 5%, n = 3) for all the target compounds. Finally, the validated method was applied to analysis the representative UV filters in water samples collected from a wastewater treatment plant in Kunming city of Yunnan province.

  5. Measurement of nitrite in urine by gas chromatography-mass spectrometry.

    PubMed

    Tsikas, Dimitrios; Suchy, Maria-Theresia; Mitschke, Anja; Beckmann, Bibiana; Gutzki, Frank-Mathias

    2012-01-01

    Nitric oxide (NO) is enzymatically produced from L-arginine and has a variety of biological functions. Autoxidation of NO in aqueous media yields nitrite (O = N-O(-)). NO and nitrite are oxidized in erythrocytes by oxyhemoglobin to nitrate (NO(3)(-)). Nitrate reductases from bacteria reduce nitrate to nitrite. Nitrite and nitrate are ubiquitous in nature, they are present throughout the body and they are excreted in the urine. Nitrite in urine has been used for several decades as an indicator and measure of bacteriuria. Since the identification of nitrite as a metabolite of NO, circulating nitrite is also used as an indicator of NO synthesis and is considered an NO storage form. In contrast to plasma nitrite, the significance of nitrite in the urine beyond bacteriuria is poorly investigated and understood. This chapter describes a gas chromatography-mass spectrometry (GC-MS) protocol for the quantitative determination of nitrite in urine of humans. Although the method is useful for detection and quantification of bacteriuria, the procedures described herein are optimum for urinary nitrite in conditions other than urinary tract infection. The method uses [(15)N]nitrite as internal standard and pentafluorobenzyl bromide as the derivatization agent. Derivatization is -performed on 100-μL aliquots and quantification of toluene extracts by selected-ion monitoring of m/z 46 for urinary nitrite and m/z 47 for the internal standard in the electron-capture negative-ion chemical ionization mode.

  6. Qualitative and quantitative characterization of protein biotherapeutics with liquid chromatography mass spectrometry.

    PubMed

    Qu, Miao; An, Bo; Shen, Shichen; Zhang, Ming; Shen, Xiaomeng; Duan, Xiaotao; Balthasar, Joseph P; Qu, Jun

    2017-11-01

    In the last decade, the advancement of liquid chromatography mass spectrometry (LC/MS) techniques has enabled their broad application in protein characterization, both quantitatively and qualitatively. Owing to certain important merits of LC/MS techniques (e.g., high selectivity, flexibility, and rapid method development), LC/MS assays are often deemed as preferable alternatives to conventional methods (e.g., ligand-binding assays) for the analysis of protein biotherapeutics. At the discovery and development stages, LC/MS is generally employed for two purposes absolute quantification of protein biotherapeutics in biological samples and qualitative characterization of proteins. For absolute quantification of a target protein in bio-matrices, recent work has led to improvements in the efficiency of LC/MS method development, sample treatment, enrichment and digestion, and high-performance low-flow-LC separation. These advances have enhanced analytical sensitivity, specificity, and robustness. As to qualitative analysis, a range of techniques have been developed to characterize intramolecular disulfide bonds, glycosylation, charge variants, primary sequence heterogeneity, and the drug-to-antibody ratio of antibody drug conjugate (ADC), which has enabled a refined ability to assess product quality. In this review, we will focus on the discussion of technical challenges and strategies of LC/MS-based quantification and characterization of biotherapeutics, with the emphasis on the analysis of antibody-based biotherapeutics such as monoclonal antibodies (mAbs) and ADCs. © 2016 Wiley Periodicals, Inc. Mass Spec Rev 36:734-754, 2017. © 2016 Wiley Periodicals, Inc.

  7. Optimization of focused ultrasonic extraction of propellant components determined by gas chromatography/mass spectrometry.

    PubMed

    Fryš, Ondřej; Česla, Petr; Bajerová, Petra; Adam, Martin; Ventura, Karel

    2012-09-15

    A method for focused ultrasonic extraction of nitroglycerin, triphenyl amine and acetyl tributyl citrate presented in double-base propellant samples following by the gas chromatography/mass spectrometry analysis was developed. A face-centered central composite design of the experiments and response surface modeling was used for optimization of the time, amplitude and sample amount. The dichloromethane was used as the extractant solvent. The optimal extraction conditions with respect to the maximum yield of the lowest abundant compound triphenyl amine were found at the 20 min extraction time, 35% amplitude of ultrasonic waves and 2.5 g of the propellant sample. The results obtained under optimal conditions were compared with the results achieved with validated Soxhlet extraction method, which is typically used for isolation and pre-concentration of compounds from the samples of explosives. The extraction yields for acetyl tributyl citrate using both extraction methods were comparable; however, the yield of ultrasonic extraction of nitroglycerin and triphenyl amine was lower than using Soxhlet extraction. The possible sources of different extraction yields are estimated and discussed. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Analysis of 62 synthetic cannabinoids by gas chromatography-mass spectrometry with photoionization.

    PubMed

    Akutsu, Mamoru; Sugie, Ken-Ichi; Saito, Koichi

    2017-01-01

    Gas chromatography-mass spectrometry (GC-MS) in electron ionization (EI) mode is one of the most commonly used techniques for analysis of synthetic cannabinoids, because the GC-EI-MS spectra contain characteristic fragment ions for identification of a compound; however, the information on its molecular ions is frequently lacking. To obtain such molecular ion information, GC-MS in chemical ionization (CI) mode is frequently used. However, GC-CI-MS requires a relatively tedious process using reagent gas such as methane or isobutane. In this study, we show that GC-MS in photoionization (PI) mode provided molecular ions in all spectra of 62 synthetic cannabinoids, and 35 of the 62 compounds showed only the molecular radical cations. Except for the 35 compounds, the PI spectra showed very simple patterns with the molecular peak plus only a few fragment peak(s). An advantage is that the ion source for GC-PI-MS can easily be used for GC-EI-MS as well. Therefore, GC-EI/PI-MS will be a useful tool for the identification of synthetic cannabinoids contained in a dubious product. To the best of our knowledge, this is the first report to use GC-PI-MS for analysis of synthetic cannabinoids.

  9. Quantitation of ibuprofen in blood using gas chromatography-mass spectrometry (GC-MS).

    PubMed

    Huber, Gerry; Garg, Uttam

    2010-01-01

    Ibuprofen is a non-narcotic, non-steroidal anti-inflammatory drug used for the treatment of pain, fever, and inflammatory diseases such as rheumatoid arthritis, osteoarthritis, and ankylosing spondylitis. It is also used for induction of closure of patent ductus arteriosus (PDA) in neonates. Although the exact mechanism of action of ibuprofen is not known, it is believed to mediate its therapeutic effects through the inhibition of cyclooxygenase and subsequently by the inhibition of prostacyclin production. As the drug has a number of side effects, which correlate to its circulating concentration, monitoring of ibuprofen in plasma or serum is desired for patients receiving high-dose therapy. Chromatographic methods are frequently used for the assay of ibuprofen, as no immunoassays are currently available.In the method described, the drug is extracted from the serum or plasma using methylene chloride and phosphate buffer (pH 6). Meclofenamic acid is used as an internal standard. The organic phase containing the drug is separated and dried under stream of nitrogen. After trimethylsilyl derivatization, analysis is done using gas-chromatography/ mass spectrometry (GC-MS). Quantification of the drug in a sample is achieved by comparing responses of the unknown sample to the responses of the calibrators using selected ion monitoring.

  10. Derivatization followed by gas chromatography-mass spectrometry for quantification of ethyl carbamate in alcoholic beverages.

    PubMed

    Xu, Xuejiao; Gao, Yihan; Cao, Xiujun; Wang, Xiang; Song, Guoxin; Zhao, Jianfeng; Hu, Yaoming

    2012-04-01

    A sensitive and rapid analytical methodology based on derivatization followed by gas chromatography-mass spectrometry (GC-MS) was developed for the quantitative determination of the toxic contaminant ethyl carbamate (EC, urethane, C(2)H(5)OCONH(2)) in alcoholic samples. EC was extracted using liquid-liquid extraction technique, and then silylated with bis-(trimethylsilyl)trifluoroacetamide, analysed finally by GC-MS. The isopropyl carbamate was used as the internal standard for quantitative analysis of EC in alcoholic samples. In this work, the sample extraction and derivatization reaction conditions were investigated, and the optimal extraction conditions obtained were: pH 9 and solvent of ethyl acetate, and the derivatization conditions were: derivatization reaction temperature of 80°C and time duration of 30 min. With the optimal conditions, the method validations were also studied. In the validation studies, EC exhibited good linearity with a regression coefficient of 0.9999. The limit of detection and limit of quantification were 0.30 and 5.0 μg/kg, respectively. The precision was less than 8.4%. Finally, the proposed technique was successfully applied to the analysis of EC in 35 kinds of alcoholic samples. The experimental results have demonstrated that the proposed technique is a fast, reliable and low-cost method for determination of EC in alcoholic samples. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Metabolic products in urine of preterm infants characterized via gas chromatography-mass spectrometry

    PubMed Central

    Hao, Hu; Li, Sitao; Zhou, Wei; Wang, Hong; Liu, Mengxian; Shi, Congcong; Chen, Jing; Xiao, Xin

    2015-01-01

    Objective: To characterize the metabolic products of urine associated with preterm birth, thus providing clinical guidelines for intestinal and parenteral nutrition in preterm infants. Methods: Urine samples of 47 preterm infants and 45 full-term infants were collected and prepared for trimethylsilylation by treatment with urease. The levels of lysine, phenylalanine, histidine, ornithine, fumaric acid, malic acid, succinic acid, lactose, stearic acid, and 4-hydroxyphenylacetic acid were detected by gas chromatography-mass spectrometry (GC/MS), and statistically analyzed. Results: The normalized concentrations of the following metabolites in preterm infant urine samples were significantly lower than that of full-term infant urine samples: lysine (P = 0.003), phenylalanine (P = 0.001), histidine (P = 0.006), ornithine (P = 0.000), fumaric acid (P = 0.002), malic acid (P = 0.006), succinic acid (P = 0.000), lactose (P = 0.000), stearic acid (P = 0.000) and 4-hydroxyphenylacetic acid (P = 0.000). Conclusions: The results of the GC/MS analysis indicated that amino acid, carbohydrate, and fatty acid metabolism defects exist in preterm infants. The use of GC/MS to determine metabolic products in urine samples could be helpful for prospectively evaluating the nutritional status of preterm infants, and therefore providing clinical guidelines on reasonable nutritional support. PMID:26629171

  12. Gas chromatography-mass spectrometry profiles of urinary organic acids in healthy captive cheetahs (Acinonyx jubatus).

    PubMed

    Tordiffe, Adrian Stephen Wolferstan; van Reenen, Mari; Reyers, Fred; Mienie, Lodewyk Jacobus

    2017-04-01

    In captivity, cheetahs (Acinonyx jubatus) frequently suffer from several unusual chronic diseases that rarely occur in their free-ranging counterparts. In order to develop a better understanding of their metabolism and health we documented the urine organic acids of 41 apparently healthy captive cheetahs, in an untargeted metabolomic study, using gas chromatography-mass spectrometry. A total of 339 organic acids were detected and annotated. Phenolic compounds, thought to be produced by the anaerobic fermentation of aromatic amino acids in the distal colon, as well as their corresponding glycine conjugates, were present in high concentrations. The most abundant organic acids in the cheetahs' urine were an as yet unidentified compound and a novel cadaverine metabolite, tentatively identified as N(1),N(5)-dimethylpentane-1,5-diamine. Pantothenic acid and citramalic acid concentrations correlated negatively with age, while glutaric acid concentrations correlated positively with age, suggesting possible dysregulation of coenzyme A metabolism in older cheetahs. This study provides a baseline of urine organic acid reference values in captive cheetahs and suggests important avenues for future research in this species.

  13. Enhanced analysis of steroids by gas chromatography/mass spectrometry using microwave-accelerated derivatization.

    PubMed

    Bowden, John A; Colosi, Dominic M; Stutts, Whitney L; Mora-Montero, Diana C; Garrett, Timothy J; Yost, Richard A

    2009-08-15

    Derivatization of steroids is typically required before analysis by gas chromatography/mass spectrometry (GC/MS); nevertheless, the derivatization process can often be time-consuming and irreproducible. Although several strategies have been employed to enhance this process, few have the potential of microwave-accelerated derivatization (MAD) to be more efficient than traditional thermal derivatization methods. MAD using a synthesis microwave system was evaluated and compared to traditional thermal derivatization methods in terms of yield, reproducibility, and overall analysis time. Parameters affecting MAD, including reaction temperature, time, and power, were systematically optimized for several silyl reagents (BSTFA with TMCS, MSTFA, and BSA) and other derivatization procedures (MOX reagent and MTBSTFA). MSTFA was found to derivatize best with the microwave, as demonstrated by the enhanced relative response factors (RRFs). BSTFA with TMCS, on the other hand, did not couple as well, but RRF values improved significantly upon addition of polar solvents. The rapid (1 min) derivatization reactions associated with MAD had comparable RRFs for all reagents with those obtained with thermal heating (>30 min). This study highlights the best methods for analyzing a comprehensive variety of steroids and also provides ideal strategies for MAD of steroids on an individual or class level.

  14. Aromatic resin characterisation by gas chromatography-mass spectrometry. Raw and archaeological materials.

    PubMed

    Modugno, Francesca; Ribechini, Erika; Colombini, Maria Perla

    2006-11-17

    An analytical procedure based on alkaline hydrolysis, solvent extraction and trimethyl-silylation followed by gas chromatography-mass spectrometry (GC-MS) analysis was used to study the chemical composition of benzoe and storax resins, water-insoluble exudates of trees of the Styrax and Liquidambar genus. They are chemically characterised by having aromatic acids, alcohols and esters as their main components and are thus known as aromatic and/or balsamic resins. This analytical procedure allowed us to characterise the main components of the two resins and, even though cinnamic acid is the main component of both the resins, the presence of other characteristic aromatic compounds and triterpenes permitted us to distinguish between the two materials. All the compounds identified in benzoe resin were detected in an archaeological organic residue from an Egyptian ceramic censer (fifth to seventh centuries a.d.), thus proving that this resin was used as one of the components of the mixture of organic materials burned as incense. These results provide the first chemical evidence of the presence of benzoe resin in an archaeological material from Mediterranean area.

  15. Contributions of liquid chromatography-mass spectrometry to "highlights" of biomedical research.

    PubMed

    Gelpí, Emilio

    2003-06-06

    Combined chromatographic and mass spectrometric techniques and in particular liquid chromatography-mass spectrometry (LC-MS) have been contributing in a decisive way to the progress of life sciences in general. Thus, the number of document entries in the US National Library of Medicine (MEDLINE) for articles dealing with LC-MS was 738 in 1991 and 2285 in 2001, with a total of 13 147 for the whole 10-year period, an increase of 310%. From these figures, we can ascertain that the total usage of combined LC-MS techniques is of the order of 40% relative to all of the MS publications collected in MEDLINE for the same period. However, from the perspective of real advances in medicine, it becomes difficult to identify what is outstanding in this field. The aim of this review was not to provide another LC-MS review, but an overview of the current status of the presence, visibility and impact of combined LC-MS techniques in biomedical research. The idea being to spot "highlight" literature contributions with the potential to become in the short or medium term real assets in a doctor's daily medical practice. In other words, after several truly remarkable technical achievements reported within the past decade, are we any closer to making LC-MS a useful and practical diagnostic tool for molecular diagnostics and personalized medicine? To approach this question, a literature survey was carried out to define: (i) the presence of LC-MS in the biomedical literature (MEDLINE) and its weight relative to the whole field of biological and biomedical mass spectrometry; (ii) the role of LC-MS in recent milestone biomedical contributions; and (iii) the present and future role of new LC-MS technology in medical diagnosis.

  16. Analysis of macrolide antibiotics, using liquid chromatography-mass spectrometry, in food, biological and environmental matrices.

    PubMed

    Wang, Jian

    2009-01-01

    Macrolides are a group of antibiotics that have been widely used in human medical and veterinary practices. Analysis of macrolides and related compounds in food, biological, and environmental matrices continue to be the focus of scientists for the reasons of food safety, pharmacokinetic studies, and environmental concerns. This article presents an overview on the primary biological properties of macrolides and their associated analytical issues, including extraction, liquid chromatography-mass spectrometry (LC-MS), method validation, and measurement uncertainty. The main techniques that have been used to extract macrolides from various matrices are solid-phase extraction and liquid-liquid extraction. Conventional liquid chromatography (LC) with C18 columns plays a dominant role for the determination of macrolides, whereas ultra-performance liquid chromatography (UPLC) along with sub-2 microm particle C18 columns reduces run time and improves sensitivity. Mass spectrometry (MS), serving as a universal detection technique, has replaced ultraviolet (UV), fluorometric, and electrochemical detection for multi-macrolide analysis. The triple-quadrupole (QqQ), quadrupole ion trap (QIT), triple-quadrupole linear ion trap, time-of-flight (TOF), and quadrupole time-of-flight (QqTOF) mass spectrometers are current choices for the determination of macrolides, including quantification, confirmation, identification of their degradation products or metabolites, and structural elucidation. LC or UPLC coupled to a triple-quadrupole mass spectrometer operated in the multiple-reaction monitoring (MRM) mode (LC/MS/MS) is the first choice for quantification. UPLC-TOF or UPLC-QqTOF has been recognized as an emerging technique for accurate mass measurement and unequivocal identification of macrolides and their related compounds.

  17. Identifying and quantifying contaminants contributing to endogenous analytes in gas chromatography/mass spectrometry.

    PubMed

    Tsikas, Dimitrios

    2010-09-15

    Contaminants from various sources including medical devices, laboratory materials and the environment, and analytical apparatus may contribute to their endogenous congeners at different stages of the analytical process. Here, an approach is reported for the identification and quantification of contaminating analytes in biological fluids by stable-isotope dilution gas chromatography/mass spectrometry (GC/MS) and gas chromatography/tandem mass spectrometry (GC/MS/MS) methods. This approach is based on the analysis of different sample volumes and determination of the peak area ratio (PAR) of the endogenous analyte to the stable-isotope labeled analogue serving as the internal standard. The PAR is obtained by selected-ion monitoring or selected-reaction monitoring of appropriate ions. Generation of PAR values that correlate inversely with the sample volume subjected to analysis reveals the existence of contamination. The extent of contamination is obtained by plotting the PAR of endogenous analyte to internal standard versus the reciprocal of the sample volume analyzed. Examples are given for uncontaminated and contaminated endogenous analytes in biological samples, including nitrite and nitrate analyzed by GC/MS, and the fatty acid metabolites oleic acid oxide, oleic acid ethanol amide, and arachidonic acid ethanol amide analyzed by GC/MS/MS. Dependence of the PAR of endogenous analyte to its internal standard upon derivatization time reveals a unique kind of contamination that was identified in the GC/MS analysis of nitrate in plasma as pentafluorobenzyl ester. This kind of contamination occurs at the latest stage of GC/MS analysis and cannot be controlled by reference to the internal standard.

  18. Laser desorption fast gas chromatography-mass spectrometry in supersonic molecular beams.

    PubMed

    Shahar, T; Dagan, S; Amirav, A

    1998-06-01

    A novel method for fast analysis is presented. It is based on laser desorption injection followed by fast gas chromatography-mass spectrometry (GC-MS) in supersonic molecular beams. The sample was placed in an open air or purged laser desorption compartment, held at atmospheric pressure and near room temperature conditions. Desorption was performed with a XeCl Excimer pulsed laser with pulse energy of typically 3 mJ on the surface. About 20 pulses at 50 Hz were applied for sample injection, resulting in about 0.4 s injection time and one or a few micrograms sample vapor or small particles. The laser desorbed sample was further thermally vaporized at a heated frit glass filter located at the fast GC inlet. Ultrafast GC separation and quantification was achieved with a 50-cm-long megabore column operated with a high carrier gas flow rate of up to 240 mL/min. The high carrier gas flow rate provided effective and efficient entrainment of the laser desorbed species in the sweeping gas. Following the fast GC separation, the sample was analyzed by mass spectrometry in supersonic molecular beams. Both electron ionization and hyperthermal surface ionization were employed for enhanced selectivity and sensitivity. Typical laser desorption analysis time was under 10 s. The laser desorption fast GC-MS was studied and demonstrated with the following sample/matrices combinations, all without sample preparation or extraction: (a) traces of dioctylphthalate plasticizer oil on stainless steel surface and the efficiency of its cleaning; (b) the detection of methylparathion and aldicarb pesticides on orange leaves; (c) water surface analysis for the presence of methylparathion pesticide; (d) caffeine analysis in regular and decaffeinated coffee powder; (e) paracetamol and codeine drug analysis in pain relieving drug tablets; (f) caffeine trace analysis in raw urine; (g) blood analysis for the presence of 1 ppm lidocaine drug. The features and advantages of the laser desorption fast GC

  19. A Gas Chromatography-Mass Spectrometry Method for the Detection and Quantitation of Monofluoroacetate in Plants Toxic to Livestock.

    PubMed

    Santos-Barbosa, Joyce M; Lee, Stephen T; Cook, Daniel; Gardner, Dale R; Viana, Luis Henrique; Ré, Nilva

    2017-02-22

    Monofluoroacetate (MFA) is a potent toxin that occurs in over 50 plant species in Africa, Australia, and South America and is responsible for significant livestock deaths in these regions. A gas chromatography-mass spectrometry (GC-MS) method for the analysis of MFA in plants based on the derivatization of MFA with n-propanol in the presence of sulfuric acid to form propyl fluoroacetate was developed. This method compared favorably to a currently employed high-performance liquid chromatography-mass spectrometry (HPLC-MS) method for the analysis of MFA in plants. The GC-MS method was applied to the analysis of MFA in herbarium specimens of Fridericia elegans, Niedenzuella stannea, N. multiglandulosa, N. acutifolia, and Aenigmatanthera lasiandra. This is the first report of MFA being detected in F. elegans, N. multiglandulosa, N. acutifolia, and A. lasiandra, some of which have been reported to cause sudden death or that are toxic to livestock.

  20. Identifying Ca2+-Binding Sites in Proteins by Liquid Chromatography-Mass Spectrometry Using Ca2+-Directed Dissociations

    PubMed Central

    Jamalian, Azadeh; Sneekes, Evert-Jan; Wienk, Hans; Dekker, Lennard J. M.; Ruttink, Paul J. A.; Ursem, Mario; Luider, Theo M.; Burgers, Peter C.

    2014-01-01

    Here we describe a new method to identify calcium-binding sites in proteins using high-resolution liquid chromatography-mass spectrometry in concert with calcium-directed collision-induced dissociations. Our method does not require any modifications to the liquid chromatography-mass spectrometry apparatus, uses standard digestion protocols, and can be applied to existing high-resolution MS data files. In contrast to NMR, our method is applicable to very small amounts of complex protein mixtures (femtomole level). Calcium-bound peptides can be identified using three criteria: (1) the calculated exact mass of the calcium containing peptide; (2) specific dissociations of the calcium-containing peptide from threonine and serine residues; and (3) the very similar retention times of the calcium-containing peptide and the free peptide. PMID:25023127

  1. Identification of organic acids as potential biomarkers in the urine of autistic children using gas chromatography/mass spectrometry.

    PubMed

    Kałużna-Czaplińska, Joanna; Żurawicz, Ewa; Struck, Wiktoria; Markuszewski, Michał

    2014-09-01

    There is a need to identify metabolic phenotypes in autism as they might each require unique approaches to prevention. Biological markers can help define autism subtypes and reveal potential therapeutic targets. The aim of the study was to identify alterations of small molecular weight compounds and to find potential biomarkers. Gas chromatography/mass spectrometry was employed to evaluate major metabolic changes in low molecular weight urine metabolites of 14 children with autism spectrum disorders vs. 10 non-autistic subjects. The results prove the usefulness of an identified set of 21 endogenous compounds (including 14 organic acids), whose levels are changed in diseased children. Gas chromatography/mass spectrometry method combined with multivariate statistical analysis techniques provide an efficient way of depicting metabolic perturbations of diseases, and may potentially be applicable as a novel strategy for the noninvasive diagnosis and treatment of autism.

  2. Identification of New Metabolites of Bacterial Transformation of Indole by Gas Chromatography-Mass Spectrometry and High Performance Liquid Chromatography

    PubMed Central

    Arora, Pankaj Kumar

    2014-01-01

    Arthrobacter sp. SPG transformed indole completely in the presence of an additional carbon source. High performance liquid chromatography and gas chromatography-mass spectrometry detected indole-3-acetic acid, indole-3-glyoxylic acid, and indole-3-aldehyde as biotransformation products. This is the first report of the formation of indole-3-acetic acid, indole-3-glyoxylic acid, and indole-3-aldehyde from indole by any bacterium. PMID:25548566

  3. Quantitation of opioids in whole blood by electron impact-gas chromatography-mass spectrometry.

    PubMed

    Tiscione, Nicholas B; Shan, Xiaoqin; Alford, Ilene; Yeatman, Dustin Tate

    2011-03-01

    Opioids are frequently encountered in Forensic Toxicology casework. A PubMed literature search was conducted to find a method using electron impact-gas chromatography-mass spectrometry to examine whole blood specimens. A previously published method was identified, and an updated version was provided by the State of North Carolina Office of the Chief Medical Examiner. This procedure was used as a starting point for development and validation of a refined procedure to be used in the Palm Beach County Sheriff's Office Forensic Toxicology laboratory for routine analysis of antemortem forensic toxicology case samples. Materials and instrumentation common to most forensic toxicology laboratories were utilized while obtaining detection limits from 1 to 10 ng/mL and quantitation limits of 2.5 to 10 ng/mL using 1 mL of whole blood. Target compounds were chosen based on applicability to the method as well as availability and common use in the United States and include dihydrocodeine, codeine, morphine, hydrocodone, 6-monoacetylmorphine, hydromorphone, oxycodone, and oxymorphone. Each analyte demonstrated two zero-order linear ranges (r(2) > 0.990) over the concentrations evaluated (from 2.5 to 500 ng/mL). The coefficient of variation of replicate analyses was less than 12%. Quantitative accuracy was within ± 27% at 2.5 ng/mL, ± 11% at 10 ng/mL, and ± 8% at 50 ng/mL. The validated method provides a more sensitive procedure for the quantitation of common opioids in blood using standard laboratory equipment and a small amount of sample.

  4. Quantitation of benzodiazepines in whole blood by electron impact-gas chromatography-mass spectrometry.

    PubMed

    Tiscione, Nicholas B; Shan, Xiaoqin; Alford, Ilene; Yeatman, Dustin Tate

    2008-10-01

    Benzodiazepines are frequently encountered in forensic toxicology. A literature search was conducted to find a simple method using electron impact-gas chromatography-mass spectrometry (EI-GC-MS) to examine whole blood specimens for the most commonly encountered benzodiazepines in the United States. A recently published method was identified in the literature search and used as a starting point for development of a new procedure to be used for routine analysis of forensic toxicology case samples. The procedure was then developed and validated as a rapid and efficient method for the screening and quantitation of benzodiazepines in blood using liquid-liquid extraction and EI-GC-MS in selective ion monitoring mode. Materials and instrumentation common to most forensic toxicology laboratories were utilized while obtaining LODs from 5 to 50 ng/mL and LOQs of 50 ng/mL or less using 1 mL of sample. Target compounds were chosen based on availability and common use in the United States and include diazepam, desalkylflurazepam, nordiazepam, midazolam, oxazepam, temazepam, lorazepam, clonazepam, and alprazolam (relative elution order). The linear range (r2 > 0.990) was validated from 50 to 1000 ng/mL for all analytes. The CV of replicate analyses at both 50 and 200 ng/mL was less than 4%. Quantitative accuracy was within +/- 16% at 50 ng/mL and within +/- 7% at 200 ng/mL. The validated method provides an efficient procedure for the quantitation of a broad range of the most common benzodiazepines in blood at meaningful limits of detection and quantitation using standard laboratory equipment and a small amount of sample.

  5. [Simultaneous determination of five hypertoxic rodenticides in serum by gas chromatography-mass spectrometry].

    PubMed

    Huang, Huiqiu; Huang, Xun; Yu, Jingsun

    2015-03-01

    A fast analytical method based on gas chromatography-mass spectrometry (GC-MS) was established for the simultaneous determination of tetramine, fluoroacetamide, sodium fluoroacetate, gliftor I and gliftor II in serum. At pH 2.0, sodium fluoroacetate was derivatizated at room temperature for 5 min by using N,N-diethyl-p-phenylenediamine as the derivatization reagent and N, N'-dicyclohexylcarbodiimide as the catalyst. The derivative and other rodenticides were extracted with ethyl acetate and concentrated with nitrogen at 50 °C, then determined by GC-MS in selected ion monitoring (SIM) mode, and quantified with matrix-match standard solutions. The analysis was carried out on an ionic liquid chromatographic capillary column (SLB-IL59, 30 m x 0.25 mm x 0.20 µm, maximum temperature 300 °C) at a flow rate of 1.0 mL/min, and the five rodenticides were successfully separated in 15 min when temperature programming was used. The results showed that the calibration curves were linear in the range of 0.01-1.0 mg/L, except for fluoroacetamide (0.02-2.0 mg/L) and tetramine (0.02-10 mg/L), with correlation coefficients (R2) greater than 0.995, and the limits of detection (LODs) were 0.001-0.002 mg/L (S/N = 3). The recoveries were 84.0%-110.0% at three different spiked levels, and the relative standard deviations (RSDs) were 2.9%-7.5% (n = 6). The method is simple, accurate, highly sensitive and suitable for the detection of the five hypertoxic rodenticides in serum for toxicological purposes.

  6. Development of a liquid chromatography/mass spectrometry-based drug accumulation assay in Pseudomonas aeruginosa.

    PubMed

    Cai, Hongliang; Rose, Kelly; Liang, Lan-Hsin; Dunham, Steve; Stover, Charles

    2009-02-15

    Bacterial resistance to antibiotic therapy remains a worldwide problem. In Pseudomonasaeruginosa, rates of efflux confer inherent resistance to many antimicrobial agents, including fluoroquinolones, due to a high level of expression and a relatively high turnover number of the efflux pumps in gram-negative bacteria. To understand the roles of efflux pumps in both the influx and efflux of compounds in P. aeruginosa and to aid the chemistry compound design by bridging in vitro enzymatic binding data (IC(50) values) with whole cell results (MIC numbers), a collaborative effort was put forward to validate a series of bacterial penetration/accumulation assays for assessment of intracellular drug concentration. Initially, using 2-(4-dimethylaminostyryl)-1-ethylpyridinium cation (DMP) as the tracer, a 96-well fluorescence assay was established to measure the time-dependent accumulation of DMP in wild-type (PAO1), MexABOprM deletion (PAO200), and MexABOprM-MexCDOprJ-MexJKL:FRT deletion mutants (PAO314). At steady state, the order of DMP accumulation was PAO314>PAO200>PAO1. Subsequently, the established assay conditions were applied to a radiolabeled assay format using (3)H-labeled ciprofloxacin. At the concentration tested, the accumulation of [(3)H]ciprofloxacin approached a plateau after 15 min and the amount of accumulation in PAO314 was higher (~2- to 10-fold) than that in PAO1. Finally, with an additional step of cell lysis, a liquid chromatography/mass spectrometry-based assay was established with ciprofloxacin with (i) superior sensitivity (the detection limit can be as low as 0.24 ng/ml for ciprofloxacin) and (ii) the ability to monitor cold or nonfluorescent compounds in a drug discovery setting.

  7. Liquid-chromatography mass spectrometry (LC-MS) of steroid hormone metabolites and its applications

    PubMed Central

    Penning, Trevor M.; Lee, Seon-Hwa; Jin, Yi; Gutierrez, Alejandro; Blair, Ian A.

    2010-01-01

    Advances in liquid chromatography-mass spectrometry (LC-MS) can be used to measure steroid hormone metabolites in vitro and in vivo. We find that LC-Electrospray Ionization (ESI)-MS using a LCQ ion trap mass spectrometer in the negative ion mode can be used to monitor the product profile that results from 5α–dihydrotestosterone(DHT)-17β-glucuronide, DHT-17β-sulfate, and tibolone-17β-sulfate reduction catalyzed by human members of the aldo-keto reductase (AKR) 1C subfamily and assign kinetic constants to these reactions. We also developed a stable-isotope dilution LC-electron capture atmospheric pressure chemical ionization (ECAPCI)-MS method for the quantitative analysis of estrone (E1) and its metabolites as pentafluorobenzyl (PFB) derivatives in human plasma in the attomole range. The limit of detection for E1-PFB was 740 attomole on column. Separations can be performed using normal-phase LC because ionization takes place in the gas phase rather than in solution. This permits efficient separation of the regioisomeric 2- and 4-methoxy-E1. The method was validated for the simultaneous analysis of plasma E2 and its metabolites: 2-methoxy-E2, 4-methoxy-E2, 16α-hydroxy-E2, estrone (E1), 2-methoxy-E1, 4-methoxy-EI, and 16α-hydroxy-E1 from 5 pg/mL to 2,000 pg/mL. Our LC-MS methods have sufficient sensitivity to detect steroid hormone levels in prostate and breast tumors and should aid their molecular diagnosis and treatment. PMID:20083198

  8. Rapid analysis of benzoylecgonine in urine by fast gas chromatography-mass spectrometry.

    PubMed

    Romberg, Robert W; Jamerson, Matthew H; Klette, Kevin L

    2006-10-01

    A novel fast gas chromatography-mass spectrometry (FGC-MS) analytical method for benzoylecgonine (BZE) has been developed to improve the efficiency of specimen analysis without diminishing the reliability of metabolite identification and quantification. Urine specimens were spiked with deuterated internal standard (BZE-d8), subjected to solid-phase extraction, and derivatized with pentafluoropropionic anhydride (PFPA) and pentafluoropropanol (PFPOH). The pentafluoropropyl ester derivative of BZE was identified and quantified using both a standard GC-MS method and the newly developed FGC-MS method. Shorter GC analyte retention times were made possible in the FGC-MS method by employing a 220-volt GC oven controller, which allowed an increased temperature ramp rate. The FGC-MS method was linear between 25 and 10,000 ng/mL of BZE yielding a correlation coefficient of 0.9994. The intra-assay precision of a 100 ng/mL BZE standard (n=15) yielded an average concentration of 99.7 ng/mL and a coefficient of variation of 1.2%. The interassay precision of 21 sets of 50, 100, and 125 ng/mL BZE controls was found to be acceptable, with coefficients of variation less than 2.4%. No interference was observed when the FGC-MS method was challenged with cocaine, ecgonine, ecgonine methyl ester, and nine other drugs of abuse. Analysis of presumptively positive specimens (n=146) by both analytical methods yielded comparable results with a correlation coefficient of 0.996. The FGC-MS method, when compared with a standard GC-MS method, reduces total assay time by approximately 50% while demonstrating comparable reliability.

  9. Determination of chlorophylls and their derivatives in Gynostemma pentaphyllum Makino by liquid chromatography-mass spectrometry.

    PubMed

    Huang, S C; Hung, C F; Wu, W B; Chen, B H

    2008-09-10

    The objectives of this study were to develop a high performance liquid chromatography-mass spectrometry (HPLC-MS) method for determination of chlorophylls and their derivatives in Gynostemma pentaphyllum Makino, a traditional Chinese herb possessing vital biological activities. Chlorophylls were extracted with a quaternary solvent system of hexane-acetone-ethanol-toluene (10:7:6:7, v/v/v/v), followed by separation of a total of 15 chlorophylls and their derivatives within 32 min using a gradient mobile phase of acetone, acetonitrile and methanol and a HyPURITY C18 column, with detection at 660 nm and flow rate at 1 mL/min. Identification was carried out on the basis of retention behavior, absorption spectra and mass spectra using atmospheric pressure chemical ionization (APCI) in positive ion mode for detection. Of the 15 analytes, chlorophyll a, chlorophyll b, pheophytin a and pheophytin b were quantified by using standard calibration curves, with the other 11 being quantified with an internal standard Fast Green FCF. Chlorophyll extracts in G. pentaphyllum were found to contain pheophytin a (2508.3 microg/g), pheophytin a' (111.2 microg/g), chlorophyll a (113.8 microg/g), chlorophyll a' (11.0 microg/g), hydroxypheophytin a (88.6 microg/g), hydroxypheophytin a' (66.5 microg/g), pyropheophytin a (76.0 microg/g), hydroxychlorophyll a (23.8 microg/g), pheophytin b (319.6 microg/g), pheophytin b' (13.2 microg/g), chlorophyll b (287.9 microg/g), chlorophyll b' (11.1 microg/g), hydroxychlorophyll b (15.0 microg/g), hydroxypheophytin b (11.2 microg/g) and hydroxypheophytin b' (8.5 microg/g).

  10. Integration of Electrochemistry with Ultra Performance Liquid Chromatography/Mass Spectrometry (UPLC/MS)

    PubMed Central

    Cai, Yi; Zheng, Qiuling; Liu, Yong; Helmy, Roy; Loo, Joseph A.; Chen, Hao

    2015-01-01

    This study presents the development of ultra-performance liquid chromatography/mass spectrometry (UPLC/MS) combined with electrochemistry (EC) for the first time and its application for the structural analysis of disulfide bond-containing proteins/peptides. In our approach, a protein/peptide mixture sample undergoes fast UPLC separation and subsequent electrochemical reduction in an electrochemical flow cell followed by online MS and MS/MS analyses. The electrochemical cell is coupled to MS using our recently developed desorption electrospray ionization (DESI) interface. Using this UPLC/EC/DESI-MS method, disulfide bond-containing peptides can be differentiated from those without disulfide bonds as the former are electroactive and reducible. Tandem MS analysis of the disulfide-reduced peptide ions provides increased sequence and disulfide linkage pattern information. In a reactive DESI-MS detection experiment in which a supercharging reagent was used to dope the DESI spray solvent, increased charging was obtained for the UPLC-separated proteins. Strikingly, upon online electrolytic reduction, supercharged proteins (e.g., α-lactalbumin) showed even higher charging, which would be useful in top-down protein structure analysis as increased charges are known to promote protein ion dissociation. Also, the separation speed and sensitivity are enhanced by approximately 1~2 orders of magnitude by using UPLC for the LC/EC/MS platform, in comparison to the previously used high performance liquid chromatography (HPLC). This UPLC/EC/DESI-MS method combines the power of fast UPLC separation, fast electrochemical conversion and online MS structural analysis for a potentially valuable tool for proteomics research and bioanalysis. PMID:26307715

  11. Relative binding affinities of integrin antagonists by equilibrium dialysis and liquid chromatography-mass spectrometry.

    PubMed

    Tipping, William J; Tshuma, Nkazimulo; Adams, James; Haywood, Harvey T; Rowedder, James E; Fray, M Jonathan; McInally, Thomas; Macdonald, Simon J F; Oldham, Neil J

    2015-02-12

    The integrin αvβ6 is a potential target for treatment of idiopathic pulmonary fibrosis (IPF). Equilibrium dialysis (ED) was investigated for its ability to report ligand binding in an αvβ6 inhibitor screening assay. As a preliminary experiment, an established peptidomimetic inhibitor of the integrin was dialyzed against αvβ6, and the fraction bound (f b) and percentage saturation determined by liquid chromatography-mass spectrometry (LC-MS) analysis. Quantitation of the inhibitor in the two chambers of the ED cartridge revealed an uneven distribution in the presence of αvβ6, corresponding to near saturation binding to the protein (93 ± 3%), while the control (without integrin) showed an equal partitioning of the inhibitor on either side of the dialysis membrane. A competitive ED assay with a 12 component mixture of antagonists was conducted, and the results compared with an established cell adhesion assay for quantifying αvβ6 inhibition of individual antagonists. Compounds clustered into three groupings: those with pIC 50 values between ca. 5.0 and 5.5, which possessed ED f b values indistinguishable from the controls, those with pIC 50s of 6.5 ± 0.2, which exhibited detectable integrin binding (f b 13-25%) in the ED assay, and a single compound of pIC 50 7.2 possessing an f b value of 38%. A good correlation between ED-derived f b and pIC 50 was observed despite the two assays utilizing quite different outputs. These results demonstrate that ED with LC-MS detection shows promise as a rapid αvβ6 integrin antagonist screening assay for mixtures of putative ligands.

  12. Urine Mescaline Screening With a Biochip Array Immunoassay and Quantification by Gas Chromatography-Mass Spectrometry.

    PubMed

    Battal, Dilek; Barnes, Allan J; Castaneto, Marisol S; Martin, Thomas M; Klette, Kevin L; Huestis, Marilyn A

    2015-12-01

    Mescaline, the primary psychoactive chemical in peyote cactus, has been consumed for thousands of years in ancient religious ceremonies. The US military wanted to determine if mescaline intake was a problem for personnel readiness. Twenty thousand seventeen urine specimens negative for cannabinoids, cocaine, opiates, and amphetamines were tested for mescaline with the Randox Drugs of Abuse V (DOA-V) biochip array immunoassay at the manufacturer's recommended cutoff of 6 mcg/L. A sensitive and specific method for mescaline quantification in urine was developed and fully validated. Extracted analytes were derivatized with pentafluoropropionic anhydride and pentafluoropropanol and quantified by gas chromatography-mass spectrometry (GC/MS) with electron impact ionization. Standard curves, using linear least squares regression with 1/x weighting, were linear from 1 to 250 mcg/L with coefficients of determination >0.994. Intra- and inter-assay imprecision was <4.4 coefficient of variation (%CV), with accuracies >90.4%. Mean extraction efficiencies were >92.0% across the linear range. This fully validated method was applied for the confirmation of urinary mescaline in 526 presumptive-positive specimens and 198 randomly selected presumptive-negative specimens at the manufacturer's 6 mcg/L cutoff. No specimen confirmed positive at the GC/MS limit of quantification of 1 mcg/L. Results indicated that during this time frame, there was insufficient mescaline drug use in the military to warrant routine screening in the drug testing program. However, mescaline stability, although assessed, could have contributed to lower prevalence. We also present a validated GC/MS method for mescaline quantification in urine for reliable confirmation of suspected mescaline intake.

  13. Analysis of acetylene in blood and urine using cryogenic gas chromatography-mass spectrometry.

    PubMed

    Kashiwagi, Masayuki; Hara, Kenji; Fujii, Hiroshi; Kageura, Mitsuyoshi; Takamoto, Mutsuo; Matsusue, Aya; Sugimura, Tomoko; Kubo, Shin-ichi

    2009-09-01

    A method for quantitative analysis of acetylene in blood and urine samples was investigated. Using cryogenic gas chromatography-mass spectrometry (GC-MS), acetylene was measured with isobutane as the internal standard in the headspace method, which revealed a linear response over the entire composite range with an excellent correlation coefficient, both in blood (R = 0.9968, range = 5.39-43.1 microg/ml) and urine (R = 0.9972, range = 2.16-10.8 microg/ml). The coefficients of variation (CV) for blood ranged from 2.62 to 11.6% for intra-day and 4.55 to 10.4% for inter-day. The CV for urine ranged from 2.38 to 3.10% for intra-day and 4.83 to 11.0% for inter-day. The recovery rate as an index of accuracy ranged from 83 to 111%. The present method showed good reliability, and is also simple and rapid. In actual samples from a charred cadaver due to acetylene explosion, the measured concentrations of acetylene by this method were 21.5 microg/ml for femoral vein blood, 17.9 microg/ml for right atrial blood, 25.5 microg/ml for left atrial blood and 7.49 microg/ml for urine. Quantification of acetylene provides important information, because the acetylene concentration is a vital reaction or sign. For example, when acetylene is filled in a closed space and then explodes, in antemortem explosion, the blood acetylene concentration of the cadaver might be significant. On the other hand, in postmortem explosion, acetylene is not detected in blood. Furthermore, when several victims are involved in one explosion, comparison of the sample concentrations can also provide useful information to establish the conditions at the accident scene; therefore, the present method is useful in forensics.

  14. Gas chromatography-mass spectrometry analysis of nitrite in biological fluids without derivatization.

    PubMed

    Tsikas, Dimitrios; Böhmer, Anke; Mitschke, Anja

    2010-06-15

    We report on a gas chromatography-mass spectrometry (GC-MS) method for the quantification of nitrite in biological fluids without preceding derivatization. This method is based on the solvent extraction with ethyl acetate of nitrous acid (HONO, pK(a) = 3.29), i.e., HO(14)NO and (15)N-labeled nitrous acid (HO(15)NO) which was supplied as the sodium salt of (15)N-labeled nitrite and served as the internal standard. HO(14)NO and HO(15)NO react within the injector (at 300 degrees C) of the gas chromatograph with the solvent ethyl acetate to form presumably unlabeled and (15)N-labeled acetyl nitrite, respectively. Under negative ion chemical ionization (NICI) conditions with methane as the reagent gas, these species ionize to form O(14)NO(-) (m/z 46) and O(15)NO(-) (m/z 47), respectively. Quantification is performed by selected ion monitoring of m/z 46 for nitrite and m/z 47 for the internal standard. Nitrate at concentrations up to 20 mM does not interfere with nitrite analysis in this method. The GC-MS method was validated for the quantification of nitrite in aqueous buffer, human urine (1 mL, acidification) and saliva (0.1-1 mL, acidification), and hemolysates. The method was applied in studying reactions of nitrite (0-10 mM) with oxyhemoglobin ( approximately 6 mM) in lysed human erythrocytes (100 microL aliquots, no acidification).

  15. Linker-assisted immunoassay and liquid chromatography/mass spectrometry for the analysis of glyphosate

    USGS Publications Warehouse

    Lee, E.A.; Zimmerman, L.R.; Bhullar, B.S.; Thurman, E.M.

    2002-01-01

    A novel, sensitive, linker-assisted enzyme-linked immunosorbent assay (L'ELISA) was compared to on-line solidphase extraction (SPE) with high-performance liquid chromatography/mass spectrometry (HPLC/MS) for the analysis of glyphosate in surface water and groundwater samples. The L'ELISA used succinic anhydride to derivatize glyphosate, which mimics the epitotic attachment of glyphosate to horseradish peroxidase hapten. Thus, L'ELISA recognized the derivatized glyphosate more effectively (detection limit of 0.1 μg/L) and with increased sensitivity (10-100 times) over conventional ELISA and showed the potential for other applications. The precision and accuracy of L'ELISA then was compared with on-line SPE/HPLC/MS, which detected glyphosate and its degradate derivatized with 9-fluorenylmethyl chloroformate using negative-ion electrospray (detection limit 0.1 μg/L, relative standard deviation ±15%). Derivatization efficiency and matrix effects were minimized by adding an isotope-labeled glyphosate (2-13C15N). The accuracy of L'ELISA gave a false positive rate of 18% between 0.1 and 1.0 μg/L and a false positive rate of only 1% above 1.0 μg/L. The relative standard deviation was ±20%. The correlation of L'ELISA and HPLC/MS for 66 surface water and groundwater samples was 0.97 with a slope of 1.28, with many detections of glyphosate and its degradate in surface water but not in groundwater.

  16. Analysis of 23 polycyclic aromatic hydrocarbons in smokeless tobacco by gas chromatography-mass spectrometry.

    PubMed

    Stepanov, Irina; Villalta, Peter W; Knezevich, Aleksandar; Jensen, Joni; Hatsukami, Dorothy; Hecht, Stephen S

    2010-01-01

    Smokeless tobacco contains 28 known carcinogens and causes precancerous oral lesions and oral and pancreatic cancer. A recent study conducted by our research team identified eight different polycyclic aromatic hydrocarbons (PAHs) in U.S. moist snuff, encouraging further investigations of this group of toxicants and carcinogens in smokeless tobacco products. In this study, we developed a gas chromatography-mass spectrometry method that allows simultaneous analysis of 23 various PAHs in smokeless tobacco after a simple two-step extraction and purification procedure. The method produced coefficients of variation under 10% for most PAHs. The limits of quantitation for different PAHs varied between 0.3 and 11 ng/g tobacco, starting with a 300 mg sample. The recovery of the stable isotope-labeled internal standards averaged 87%. The method was applied to analysis of 23 moist snuff samples that included various flavors of the most popular U.S. moist snuff brands, as well as 17 samples representing the currently marketed brands of spit-free tobacco pouches, a relatively new type of smokeless tobacco. The sum of all detected PAHs in conventional moist snuff averaged 11.6 (+/-3.7) microg/g dry weight; 20% of this amount was comprised of carcinogenic PAHs. The levels of PAHs in new spit-free tobacco products were much lower than those in moist snuff; the sum of all detected PAHs averaged 1.3 (+/-0.28) microg/g dry weight. Our findings render PAHs one of the most prevalent groups of carcinogens in smokeless tobacco. Urgent measures are required from the U.S. tobacco industry to modify manufacturing processes so that the levels of these toxicants and carcinogens in U.S. moist snuff are greatly reduced.

  17. A gas chromatography-mass spectrometry method for the quantitation of clobenzorex.

    PubMed

    Cody, J T; Valtier, S

    1999-01-01

    Drugs metabolized to amphetamine or methamphetamine are potentially significant concerns in the interpretation of amphetamine-positive urine drug-testing results. One of these compounds, clobenzorex, is an anorectic drug that is available in many countries. Clobenzorex (2-chlorobenzylamphetamine) is metabolized to amphetamine by the body and excreted in the urine. Following administration, the parent compound was detectable for a shorter time than the metabolite amphetamine, which could be detected for days. Because of the potential complication posed to the interpretation of amphetamin-positive drug tests following administration of this drug, the viability of a current amphetamine procedure using liquid-liquid extraction and conversion to the heptafluorobutyryl derivative followed by gas chromatography-mass spectrometry (GC-MS) analysis was evaluated for identification and quantitation of clobenzorex. Qualitative identification of the drug was relatively straightforward. Quantitative analysis proved to be a far more challenging process. Several compounds were evaluated for use as the internal standard in this method, including methamphetamine-d11, fenfluramine, benzphetamine, and diphenylamine. Results using these compounds proved to be less than satisfactory because of poor reproducibility of the quantitative values. Because of its similar chromatographic properties to the parent drug, the compound 3-chlorobenzylamphetamine (3-Cl-clobenzorex) was evaluated in this study as the internal standard for the quantitation of clobenzorex. Precision studies showed 3-Cl-clobenzorex to produce accurate and reliable quantitative results (within-run relative standard deviations [RSDs] < 6.1%, between-run RSDs < 6.0%). The limits of detection and quantitation for this assay were determined to be 1 ng/mL for clobenzorex.

  18. Age determination of ballpoint pen ink by thermal desorption and gas chromatography-mass spectrometry.

    PubMed

    Bügler, Jürgen H; Buchner, Hans; Dallmayer, Anton

    2008-07-01

    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.

  19. Determination of lamotrigine and its metabolites in human plasma by liquid chromatography-mass spectrometry.

    PubMed

    Beck, Olof; Ohman, Inger; Nordgren, Helena K

    2006-10-01

    A method based on electrospray ionization liquid chromatography-mass spectrometry was developed for the quantitative determination of lamotrigine and three of its reported metabolites, lamotrigine-2-N-glucuronide, lamotrigine-2-N-methyl, and lamotrigine-2-N-oxide in human blood plasma. The method utilized sample preparation by precipitation of proteins with acetonitrile, chromatographic separation on a reversed-phase system by gradient elution, and monitoring of the protonated molecular ions. Two internal standards, 3,5-diamino-6-(2-methoxyphenyl)-1,2,4-triazine and morphine-3-glucuronide-D3, were utilized to achieve precise quantification. The method validation comprised a demonstration of an agreement in the quantification of lamotrigine with that of a routine HPLC-UV method. The limits of detection were between 0.05 and 0.16 micromol/L. The method was employed for the measurement of clinical samples collected from 55 patients in steady-state prior to the dose intake (trough level). Lamotrigine and the 2-N-glucuronide were typically detected, while the N-methyl and N-oxide metabolites were detected only rarely. The median lamotrigine plasma level was 24.0 micromol/L (range, 4.3 to 64 micromol/L), the median 2-N-glucuronide level was 2.4 micromol/L (range, <0.05 to 24 micromol/L), and the median lamotrigine 2-N-glucuronide/lamotrigine ratio was 0.11 (range, <0.01 to 0.64). In conclusion, this liquid chromatographic-mass spectrometric method is suitable for simultaneous determination of lamotrigine and its metabolites in human plasma.

  20. Triple sorbent thermal desorption/gas chromatography/mass spectrometry determination of vapor phase organic contaminants

    SciTech Connect

    Ma, C.Y.; Skeen, J.T.; Dindal, A.B.; Higgins, C.E.; Jenkins, R.A.

    1994-05-01

    A thermal desorption/ps chromatography/mass spectrometry (TD/GC/MS) has been evaluated for the determination of volatile organic compounds (VOCS) in vapor phase samples using Carbosieve S-III/Carbotrap/Carotrap C triple sorbent traps (TST) similar to those available from a commercial source. The analysis was carried out with a Hewlett-Packard 5985A or 5995 GC/MS system with a modified injector to adapt an inhouse manufactured short-path desorber for transferring desorbate directly onto a cryofocusing loop for subsequent GC/MS analysis. Vapor phase standards generated from twenty six compounds were used for method validation, including alkanes, alkyl alcohols, alkyl ketones, and alkyl nitrites, a group of representative compounds that have previously been identified in a target airborne matrix. The method was validated based on the satisfactory results in terms of reproducibility, recovery rate, stability, and linearity. A relative, standard deviation of 0.55 to 24.3 % was obtained for the entire TD process (generation of gas phase standards, spiking the standards on and desorbing from TST) over a concentration range of 20 to 500 ng/trap. Linear correlation coefficients for the calibration curves as determined ranged from 0.81 to 0.99 and limits of detection ranged from 3 to 76 ng. For a majority of standards, recoveries of greater than 90% were observed. For three selected standards spiked on TSTS, minimal loss (10 to 22%) was observed after storing the spiked in, a 4{degree}C refrigerator for 29 days. The only chromatographable artifact observed was a 5% conversion of isopropanol to acetone. The validated method been successfully applied, to the determination of VOCs collected from various emission sources in a diversified concentration range.

  1. Supervised pattern recognition procedures for discrimination of whiskeys from gas chromatography/mass spectrometry congener analysis.

    PubMed

    González-Arjona, Domingo; López-Pérez, Germán; González-Gallero, Víctor; González, A Gustavo

    2006-03-22

    The volatile congener analysis of 52 commercialized whiskeys (24 samples of single malt Scotch whiskey, 18 samples of bourbon whiskey, and 10 samples of Irish whiskey) was carried out by gas chromatography/mass spectrometry after liquid-liquid extraction with dichloromethane. Pattern recognition procedures were applied for discrimination of different whiskey categories. Multivariate data analysis includes linear discriminant analysis (LDA), k nearest neighbors (KNN), soft independent modeling of class analogy (SIMCA), procrustes discriminant analysis (PDA), and artificial neural networks techniques involving multilayer perceptrons (MLP) and probabilistic neural networks (PNN). Classification rules were validated by considering the number of false positives (FPs) and false negatives (FNs) of each class associated to the prediction set. Artificial neural networks led to the best results because of their intrinsic nonlinear features. Both techniques, MLP and PNN, gave zero FPs and zero FNs for all of the categories. KNN is a nonparametric method that also provides zero FPs and FNs for every class but only when selecting K = 3 neighbors. PDA produced good results also (zero FPs and FNs always) but only by selecting nine principal components for class modeling. LDA shows a lesser classification performance, because of the building of linear frontiers between classes that does not apply in many real situations. LDA led to one FP for bourbons and one FN for scotches. The worse results were obtained with SIMCA, which gave a higher number of FPs (five for both scotches and bourbons) and FNs (six for scotchs and two for bourbons). The possible cause of these findings is the strong influence of class inhomogeneities on the SIMCA performance. It is remarkable that in any case, all of the methodologies lead to zero FPs and FNs for the Irish whiskeys.

  2. Analysis of 23 polycyclic aromatic hydrocarbons in smokeless tobacco by gas chromatography-mass spectrometry

    PubMed Central

    Stepanov, Irina; Villalta, Peter W.; Knezevich, Aleksandar; Jensen, Joni; Hatsukami, Dorothy; Hecht, Stephen S.

    2009-01-01

    Smokeless tobacco contains 28 known carcinogens and causes precancerous oral lesions and oral and pancreatic cancer. A recent study conducted by our research team identified 8 different polycyclic aromatic hydrocarbons (PAH) in U.S. moist snuff, encouraging further investigations of this group of toxicants and carcinogens in smokeless tobacco products. In this study, we developed a gas chromatography-mass spectrometry method that allows simultaneous analysis of 23 various PAH in smokeless tobacco after a simple two-step extraction and purification procedure. The method produced coefficients of variation under 10% for most PAH. The limits of quantitation for different PAH varied between 0.3 ng/g tobacco and 11 ng/g tobacco, starting with a 300-mg sample. The recovery of the stable isotope-labeled internal standards averaged 87%. The method was applied to analysis of 23 moist snuff samples that include various flavors of the most popular U.S. moist snuff brands, as well as 17 samples representing the currently marketed brands of spit-free tobacco pouches, a relatively new type of smokeless tobacco. The sum of all detected PAH in conventional moist snuff averaged 11.6 (± 3.7) µg/g dry weight, 20% of this amount being comprised by carcinogenic PAH. The levels of PAH in new spit-free tobacco products were much lower than those in moist snuff, the sum of all detected PAH averaging 1.3 (±0.28) µg/g dry weight. Our findings render PAH one of the most prevalent groups of carcinogens in smokeless tobacco, along with tobacco-specific nitrosamines. Urgent measures are required from the U.S. tobacco industry to modify manufacturing processes so that the levels of these toxicants and carcinogens in the U.S. moist snuff are greatly reduced. PMID:19860436

  3. Characterization of oil shale waters by gas chromatography/mass spectrometry

    SciTech Connect

    Lane, D.C.; Baughman, K.J.; Jones, J.S.

    1986-09-01

    Characterization work has begun on organic compounds and compound classes to establish a baseline for the evaluation and development of alternative instrumental characterization techniques. For this purpose raw water from two oil shale processes has been subjected to an extraction and gas chromatography/mass spectrometry (GC/MS) analysis. Samples from the R-17 and Rio Blanco processes were chosen for comparison with previous characterization work reported by Poulson et al. (1984, 1985), who used low-cost gas and reverse-phase liquid chromatographic (LC) techniques. In addition, various inorganic and physical parameters were re-evaluated. The preliminary comparison of GC/MS data with the GC and reverse phase LC data previously reported by Poulson et al., indicates a number of positive correlations for both the process waters. Aliphatic carboxylic acids, cresols, xylenols, methyl pyridines, dimethyl pyridines, and trimethyl pyridines were found both in present GC/MS analysis and in earlier GC and LC analyses of the samples. In addition, trimethylphenols were observed in both the present GC/MS analysis and in the previous GC and LC analyses of the Rio Blanco sample. A number of tentatively identified compounds and compound classes were observed in the GC/MS analysis but were unreported in either the GC or LC analyses for both samples. Similarly, several compounds and compound classes previously reported by GC and LC techniques were absent in the GC/MS analysis. These discrepancies may be attributed to either the original GC and LC research design or to a fundamental chemical change in the samples used for the GC/MS characterization. Additional research is necessary in the areas of extraction design, use of comparable GC and GC/MS marker compounds for identification, standardization of chromatographic columns and GC conditions, and the validity of computer library identifications. 3 refs., 2 figs., 12 tabs.

  4. Nitrate Reduction in a Groundwater Microcosm Determined by 15N Gas Chromatography-Mass Spectrometry

    PubMed Central

    Bengtsson, Göran; Annadotter, Heléne

    1989-01-01

    Aerobic and anaerobic groundwater continuous-flow microcosms were designed to study nitrate reduction by the indigenous bacteria in intact saturated soil cores from a sandy aquifer with a concentration of 3.8 mg of NO3−-N liter−1. Traces of 15NO3− were added to filter-sterilized groundwater by using a Darcy flux of 4 cm day−1. Both assimilatory and dissimilatory reduction rates were estimated from analyses of 15N2, 15N2O, 15NH4+, and 15N-labeled protein amino acids by capillary gas chromatography-mass spectrometry. N2 and N2O were separated on a megabore fused-silica column and quantified by electron impact-selected ion monitoring. NO3− and NH4+ were analyzed as pentafluorobenzoyl amides by multiple-ion monitoring and protein amino acids as their N-heptafluorobutyryl isobutyl ester derivatives by negative ion-chemical ionization. The numbers of bacteria and their [methyl-3H]thymidine incorporation rates were simultaneously measured. Nitrate was completely reduced in the microcosms at a rate of about 250 ng g−1 day−1. Of this nitrate, 80 to 90% was converted by aerobic denitrification to N2, whereas only 35% was denitrified in the anaerobic microcosm, where more than 50% of NO3− was reduced to NH4+. Assimilatory reduction was recorded only in the aerobic microcosm, where N appeared in alanine in the cells. The nitrate reduction rates estimated for the aquifer material were low in comparison with rates in eutrophic lakes and coastal sediments but sufficiently high to remove nitrate from an uncontaminated aquifer of the kind examined in less than 1 month. PMID:16348048

  5. Determination of nitrogen-15 enrichment of nitrate and nitrite using thermospray liquid chromatography-mass spectrometry

    SciTech Connect

    Hogge, L.R.; Hynes, R.K.; Nelson, L.M.; Vestal, M.L.

    1986-11-01

    A new method has been developed for the determination of percent /sup 15/N enrichment in NO/sub 2//sup -/ and NO/sub 3//sup -/ that is both rapid and sensitive. NO/sub 2//sup -/ and NO/sub 3//sup -/ separation was done by use of reverse-phase liquid chromatography with a mobile phase consisting of ammonium acetate with tetrabutylammonium acetate as the ion pair reagent. The % /sup 15/N in isotopically enriched anions was determined by using thermospray liquid chromatography-mass spectrometry (LC-MS). Enrichment values were obtained on as little as 20 ng of NO/sub 2//sup -/-N/20 ..mu..L and 4 ng of NO/sub 3//sup -/-N/20 ..mu..L. The linear regression curve was plotted for the observed enrichment vs. the actual enrichment over the range from the natural abundance to 25% enrichment for each anion and the equation for the linear regression calculated (y = 1.16x + 0.7577 for NO/sub 2//sup -/ and y = 0.951x + 0.447 for NO/sub 3//sup -/). The coefficient of determination for the NO/sub 2//sup -/ and NO/sub 3//sup -/ curves was 0.988 and 0.987, respectively. The dynamic range of the method was found to be suitable for the range of NO/sub 2//sup -/ and NO/sub 3//sup -/ expected in plant xylem sap. Xylem sap samples obtained from NO/sub 3//sup -/ fed pea, Pisum sativum cv. Homesteader (3.9 ..mu..g of NO/sub 3//sup -/-N/mL, 24.7% /sup 15/N), contained a /sup 15/N enrichment of 25.4% +/- 0.7%.

  6. Trace analysis of environmental matrices by large-volume injection and liquid chromatography-mass spectrometry.

    PubMed

    Busetti, Francesco; Backe, Will J; Bendixen, Nina; Maier, Urs; Place, Benjamin; Giger, Walter; Field, Jennifer A

    2012-01-01

    The time-honored convention of concentrating aqueous samples by solid-phase extraction (SPE) is being challenged by the increasingly widespread use of large-volume injection (LVI) liquid chromatography-mass spectrometry (LC-MS) for the determination of traces of polar organic contaminants in environmental samples. Although different LVI approaches have been proposed over the last 40 years, the simplest and most popular way of performing LVI is known as single-column LVI (SC-LVI), in which a large-volume of an aqueous sample is directly injected into an analytical column. For the purposes of this critical review, LVI is defined as an injected sample volume that is ≥10% of the void volume of the analytical column. Compared with other techniques, SC-LVI is easier to set up, because it requires only small hardware modifications to existing autosamplers and, thus, it will be the main focus of this review. Although not new, SC-LVI is gaining acceptance and the approach is emerging as a technique that will render SPE nearly obsolete for many environmental applications. In this review, we discuss: the history and development of various forms of LVI; the critical factors that must be considered when creating and optimizing SC-LVI methods; and typical applications that demonstrate the range of environmental matrices to which LVI is applicable, for example drinking water, groundwater, and surface water including seawater and wastewater. Furthermore, we indicate direction and areas that must be addressed to fully delineate the limits of SC-LVI.

  7. Unconjugated morphine in blood by radioimmunoassay and gas chromatography/mass spectrometry.

    PubMed

    Spiehler, V; Brown, R

    1987-07-01

    Morphine, the active metabolite of heroin, is rapidly inactivated by glucuronidation at the 3 carbon. Unconjugated (pharmacologically active) morphine was measured in postmortem blood by radioimmunoassay using an antibody-coated tube kit. The kit shows less than 0.2% cross-reactivity with codeine and morphine-glucuronide. Unconjugated morphine concentrations were confirmed by gas chromatography/mass spectrometry (GC/MS) using deuterated morphine as the internal standard. The blood was precipitated with 10% trichloroacetic acid (TCA) and concentrated hydrochloric acid (HCl), centrifuged, and decanted. The supernatant was then either diluted (unhydrolyzed) or heated to 100 degrees C, 30 min (hydrolyzed), followed by a wash with 4:1 chloroform:isopropranol. The upper aqueous layer was then saturated with sodium bicarbonate (NaHCO3) and extracted with 4:1 chloroform:isopropranol. The organic layer was evaporated, derivatized with trifluoroacetic anhydride (TFA), and analyzed by selected ion monitoring (SIM) GC/MS. Comparison of the results for unconjugated morphine by radioimmunoassay and unhydrolyzed morphine by GC/MS gave a correlation coefficient of r = 0.98, n = 100. Unconjugated morphine ranged from 0 to 100% of total morphine with a mean of 42%, n = 200, for heroin or morphine involved deaths. Review of 56 putative rapid deaths gave a mean of 68% unconjugated morphine with a range of 26 to 100%. The ratio of unconjugated to total morphine was found to be stable in postmortem blood after more than a year of storage at room temperature, within the precision of the method.

  8. Glass bottle sampling solid phase microextraction gas chromatography mass spectrometry for breath analysis of drug metabolites.

    PubMed

    Lu, Yan; Niu, Wenqi; Zou, Xue; Shen, Chengyin; Xia, Lei; Huang, Chaoqun; Wang, Hongzhi; Jiang, Haihe; Chu, Yannan

    2017-05-05

    Breath analysis is a non-invasive approach which may be applied to disease diagnosis and pharmacokinetic study. In the case of offline analysis, the exhaled gas needs to be collected and the sampling bag is often used as the storage vessel. However, the sampling bag usually releases some extra compounds, which may interfere with the result of the breath test. In this study, a novel breath sampling glass bottle was developed with a syringe needle sampling port for solid phase microextraction (SPME). Such a glass bottle scarcely liberates compounds and can be used to collect exhaled gas for ensuing analysis by gas chromatography-mass spectrometry (GC-MS). The glass bottle sampling SPME-GC-MS analysis was carried out to investigate the breath metabolites of myrtol, a multicompound drug normally used in the treatment of bronchitis and sinusitis. Four compounds, α-pinene, 2,3-dehydro-1,8-cineole, d-limonene and 1,8-cineole were found in the exhaled breath of all eight volunteers who had taken the myrtol. While for other ten subjects who had not used the myrtol, these compounds were undetectable. In the SPME-GC-MS analysis of the headspace of myrtol, three compounds were detected including α-pinene, d-limonene and 1,8-cineole. Comparing the results of breath and headspace analysis, it indicates that 2,3-dehydro-1,8-cineole in the breath is the metabolite of 1,8-cineole. It is the first time that this metabolite was identified in human breath. The study demonstrates that the glass bottle sampling SPME-GC-MS method is applicable to exhaled gas analysis including breath metabolites investigation of drugs like myrtol. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Improved method for rapid detection of phthalates in bottled water by gas chromatography-mass spectrometry.

    PubMed

    Otero, Paz; Saha, Sushanta Kumar; Moane, Siobhan; Barron, John; Clancy, Gerard; Murray, Patrick

    2015-08-01

    An improved gas chromatography-mass spectrometry (GC-MS) method for simple, rapid and precise quantification of phthalates in drinking water is presented. This method was validated for bis (2-n-butoxyethyl) phthalate (DBEP), bis (2-n-ethylhexyl) phthalate (DEHP), butyl benzyl phthalate (BBP), di-butyl phthalate (DBP), diethyl phthalate (DEP), dihexyl phthalate (DHP), dimethyl phthalate (DMP), di-n-octyl phthalate (DNOP) and dinonyl phthalate (DINP). Linearity of 0.9984>r(2)>0.9975 in the range of 0.075-4.8μg/mL for the selected phthalates was obtained. Accuracy values were in the range of 93-114% and RSD% for the analysis of 1.2μg/mL of each phthalate was below 2.3% (n=9). This new method design has significantly improved the detection in terms of rapidity, specificity, repeatability and accuracy compared to available methods. The procedure has been applied to the analyses of three different brands of commercially available bottled mineral water and the corresponding plastic bottles. Phthalates were extracted with dichloromethane and re-constituted in cyclohexane prior to GC-MS analysis. When the validated GC-MS method was applied to the quantification of the selected phthalates in the samples, only DBP (up to 0.0675±0.0018μg/mL) and DEHP (up to 1.6848±0.1631μg/mL) were found. Furthermore, we provide specific data about the concentration of DBP and DEHP in bottled water attributable to migration of phthalates from respective plastic bottles. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Determination of seven pyrethroids and six pyrethrins in water by liquid chromatography/mass spectrometry

    NASA Astrophysics Data System (ADS)

    ccanccapa, alexander; Masia, Ana; Pico, Yolanda

    2016-04-01

    Pyrethroids are the synthetic analogues of pyrethrins which were developed as pesticides from the extracts of dried and powdered flower heads of Chrysanthemum cinerariaefolium. They are increasingly used in agriculture due to their broad biological activity and slow development of pest resistance. Contamination of fresh-water ecosystems appears either because of the direct discharge of industrial and agricultural effluents or as a result of effluents from sewage treatment works; residues can thus accumulate in the surrounding biosphere [1, 2]. These substances, mostly determined by gas chromatography mass spectrometry (GC-MS) can be difficult to analyse due to their volatility and degradability. The purpose of this study is, as an alternative, to develop a fast and sensitive multi-residue method for the target analysis of 7 pyrethroids and the 6 natural pyrethrins currently used in water samples by liquid chromatography tandem mass spectrometry (LC-MS/MS). The compounds included in the study were acrinathrin, etofenprox, cyfluthrin, esfenvalerate, cyhalothrin, cypermethrin and flumethrin as pyrethroids and a commercial mix of pyrethrins containing Cinerin I, Jasmolin I, pyrethrin I, cinerin II, jasmolin II, pyrethrins II in different percentages. As a preliminary step, the ionization and fragmentation of the compounds were optimized injecting individual solutions of each analyte at 10 ppm in the system, using a gradient elution profile of water-methanol both with 10 mM ammonium formate. The ESI conditions were: capillary voltage 4000 V, nebulizer15 psi, source temperature 300◦C and gas flow 10 L min-1. [M+H]+, [M+Na]+ ,[M+NH3]+ ,[M+NH4+]+ were tested as precursor ions. The most intense signal was for ammonium adduct for all compounds. The optimal fragmentor range for product ions were between 20 to 80 ev and the collision energy ranged between 5 to 86 ev. The efficiency of the method was tested in water samples from Turia River without any known exposure to

  11. EPA Method 525.3 - Determination of Semivolatile Organic Chemicals in Drinking Water by Solid Phase Extraction and Capillary Column Gas Chromatography/Mass Spectrometry (GC/MS)

    EPA Science Inventory

    Method 525.3 is an analytical method that uses solid phase extraction (SPE) and gas chromatography/mass spectrometry (GC/MS) for the identification and quantitation of 125 selected semi-volatile organic chemicals in drinking water.

  12. EPA Method 525.3 - Determination of Semivolatile Organic Chemicals in Drinking Water by Solid Phase Extraction and Capillary Column Gas Chromatography/Mass Spectrometry (GC/MS)

    EPA Science Inventory

    Method 525.3 is an analytical method that uses solid phase extraction (SPE) and gas chromatography/mass spectrometry (GC/MS) for the identification and quantitation of 125 selected semi-volatile organic chemicals in drinking water.

  13. Assessment of the chemical changes during storage of phenol-formaldehyde resins pyrolysis gas chromatography mass spectrometry, inverse gas chromatography and Fourier transform infra red methods.

    PubMed

    Strzemiecka, B; Voelkel, A; Zięba-Palus, J; Lachowicz, T

    2014-09-12

    The chemical changes occurring in the phenol-formaldehyde resins (resol and novolac type) during their storage were investigated. In this paper the FT-IR, py-GCMS and inverse gas chromatography methods were applied for assessment of the changes occurring during storage of the phenolic resins. We have found that during storage some examined resins occurred partial curing. The results from all techniques applied are consistent. Py-GCMS is useful technique for screening the storage processes but IGC seems to be most sensitive one.

  14. Evaluation of angiosperm and fern contributions to soil organic matter using two methods of pyrolysis-gas chromatography-mass spectrometry

    USDA-ARS?s Scientific Manuscript database

    Plant biochemical characteristics influence decomposition rates and subsequently the biochemical composition of soil organic matter. Ferns, in particular have biochemical characteristics that could influence the stability of soil organic matter (SOM), such as high concentrations of aliphatic compou...

  15. Pyrolysis gas chromatography-mass spectrometry to characterize organic matter and its relationship to uranium content of Appalachian Devonian black shales

    USGS Publications Warehouse

    Leventhal, J.S.

    1981-01-01

    Gas Chromatographic analysis of volatile products formed by stepwise pyrolysis of black shales can be used to characterize the kerogen by relating it to separated, identified precursors such as land-derived vitrinite and marine-source Tasmanites. Analysis of a Tasmanites sample shows exclusively n-alkane and -alkene pyrolysis products, whereas a vitrinite sample shows a predominance of one- and two-ring substituted aromatics. For core samples from northern Tennessee and for a suite of outcrop samples from eastern Kentucky, the organic matter type and the U content (<10-120ppm) show variations that are related to precursor organic materials. The samples that show a high vitrinite component in their pyrolysis products are also those samples with high contents of U. ?? 1981.

  16. The comparison of chemical liquid deposition and acid dealumination modified ZSM-5 for catalytic pyrolysis of pinewood using pyrolysis-gas chromatography/mass spectrometry.

    PubMed

    Zhang, Huiyan; Shao, Shanshan; Luo, Mengmeng; Xiao, Rui

    2017-11-01

    Catalyst deactivation is the main reason for low petrochemical yield in catalytic fast pyrolysis (CFP) of biomass. ZSM-5 catalysts modified by chemical liquid deposition (CLD) and acid dealumination (AD) were prepared to improve petrochemical yields for CFP of pinewood. The results showed that CLD by SiO2 led to the coverage of strong acid sites, while AD favored the removal of superficial acid sites. CFP of pinewood showed that the relative area ratio of BTX was boosted by 37.2% and 30.4% over modified ZSM-5 catalysts by CLD and AD, respectively. The yield of indenes and naphthalenes which were important precursors of heavy coke decreased sharply. Considering environmental cost and catalytic performance, CLD seems to be a preferable modification method over ZSM-5 in the catalytic pyrolysis of biomass for petrochemicals. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Pyrolysis-gas chromatography-mass spectrometry with electron-ionization or resonance-enhanced-multi-photon-ionization for characterization of polycyclic aromatic hydrocarbons in the Baltic Sea.

    PubMed

    Otto, Stefan; Streibel, Thorsten; Erdmann, Sabrina; Klingbeil, Sophie; Schulz-Bull, Detlef; Zimmermann, Ralf

    2015-10-15

    Polycyclic aromatic hydrocarbons (PAH), as a part of dissolved organic matter (DOM), are environmental pollutants of the marine compartment. This study investigates the origin of PAH, which is supposed to derive mainly from anthropogenic activities, and their alteration along the salinity gradient of the Baltic Sea. Pyrolysis in combination with gas chromatography and two mass selective detectors in one measurement cycle are utilized as a tool for an efficient trace analysis of such complex samples, by which it is possible to detect degradation products of high molecular structures. Along the north-south transect of the Baltic Sea a slightly rising trend for PAH is visible. Their concentration profiles correspond to the ship traffic as a known anthropogenic source, underlined by the value of special isomer ratios such as phenanthrene and anthracene (0.31-0.45) or pyrene and fluoranthene (0.44-0.53). The detection of naphthalene and the distribution of its alkylated representatives support this statement.

  18. Sweat testing for cocaine, codeine and metabolites by gas chromatography-mass spectrometry.

    PubMed

    Huestis, M A; Oyler, J M; Cone, E J; Wstadik, A T; Schoendorfer, D; Joseph, R E

    1999-10-15

    Sweat testing for drugs of abuse provides a convenient and considerably less invasive method for monitoring drug exposure than blood or urine. Numerous devices have been developed for collection of sweat specimens. The most common device in current use is the PharmChek Sweat Patch, which usually is worn by an individual for five to ten days. This device has been utilized in several field trials comparing sweat test results to conventional urinalysis and the results have been favorable. Two new Fast Patch devices have been developed and tested that allow rapid collection of sweat specimens. The Hand-held Fast Patch was applied to the palm of the hand and the Torso Fast Patch was applied to the abdomen or the sides of the trunk (flanks) of volunteer subjects participating in a research study. Both patches employed heat-induced sweat stimulation and a larger cellulose pad for increased drug collection. Sweat specimens were collected for 30 min at various times following administration of cocaine or codeine in controlled dosing studies. After patch removal, the cellulose pad was extracted with sodium acetate buffer, followed by solid-phase extraction. Extracts were derivatized and analyzed by gas chromatography mass spectrometry (GC-MS) simultaneously for cocaine, codeine and metabolites. Cocaine and codeine were the primary analytes detected in sweat. Peak cocaine and codeine concentrations ranged from 33 to 3579 ng/patch and 11 to 1123 ng/patch, respectively, across all doses for the Hand-held Patch compared to 22-1463 ng/patch and 12-360 ng/patch, respectively, for the Torso Fast Patch. Peak concentrations generally occurred 4.5-24 h after dosing. Both drugs could be detected for at least 48 h after dosing. Considerably smaller concentrations of metabolites of cocaine and codeine were also present in some patches. Generally, concentrations of cocaine and codeine were higher in sweat specimens collected with the Hand-held Fast Patch than for the Torso Fast Patch

  19. Detecting Organic Compounds in Martian Soil Analogues Using Gas Chromatography Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Glavin, D. P.; Buch, A.; Mahaffy, P. R.

    2004-01-01

    One of the primary objectives of the 1976 Viking missions was to determine whether organic compounds, possibly of biological origin, were present in the Martian surface soils. The Viking gas chromatography mass spectrometry (GCMS) instruments found no evidence for any organic compounds of Martian origin above a few parts per billion in the upper 10 cm of surface soil [l], suggesting the absence of a widely distributed Martian biota. However, Benner et d. have suggested that significant amounts of non-volatile organic compounds, possibly including oxidation products of bioorganic molecules (e.g. carboxylic acids) would not have been detected by the Viking GCMS [2]. Moreover, other key organic compounds important to biology, such as amino acids and nucleobases, would also likely have been missed by the Viking GCMS as these compounds require chemical derivatization to be stable in a GC column [3]. Recent pyrolysis experiments with a Mars soil analogue that had been innoculated with Escherichia coli bacteria have shown that amino acid decomposition products (amines) and nucleobases are among the most abundant products generated after pyrolysis of the bacterial cells [4,5]. At the part per billion level (Viking GCMS detection limit), these pyrolysis products generated from several million bacterial cells per gram of Martian soil would not have been detected by the Viking GCMS instruments [4]. Analytical protocols are under development for upcoming in situ lander opportunities to target several important biological compounds including amino acids and nucleobases. For example, extraction and chemical derivatization techniques [3] are being adapted for space flight use to transform reactive or fragile molecules that would not have been detected by the Viking GCMS instruments, into species that are sufficiently volatile to be detected by GCMS. Recent experiments carried out at NASA Goddard have shown that using this derivatization technique all of the targeted compounds

  20. [Gas chromatography-mass spectrometry based urinary metabolomics in very low birth weight premature infants].

    PubMed

    Li, S T; Huang, X L; Wu, S G; Ma, Y M; Shi, C C; Xiao, X; Hao, H

    2017-06-02

    Objective: To investigate the urinary metabolic spectrum and pathways in very low birth weight (VLBW) premature infants. Method: A prospective case-control study was conducted to collect and compare the data of VLBW premature infants and full term infants from the Sixth Affiliated Hospital of Sun Yet-Sen University in 2014. Within 24 hours after birth, urine specimens in each group were collected. Metabolites of urine samples including amino acid, fatty acid and organic acid were detected using the urease pre-processing and gas chromatography mass spectrometry (GC-MS) technology. Using the orthogonal partial least squares discriminant analysis (OPLS-DA), the biomarkers and differences between the two groups were found. The online metabolic pathway website was explored and multivariable analysis was conducted to investigate the valuable pathways and biomarkers related to the prematurity. Result: A total of 20 VLBW premature infants were enrolled, among whom 11 were male, 9 were female; and 20 full term infants were enrolled, among whom 9 were male, 11 were female. The urinary metabolites were established and compared between the VLBW premature and term infants. The investigation showed that the following nine pathways were enriched: amino-acyl-tRNA biosynthesis(P=0.000), lysine degradation(P=0.007), fatty acid biosynthesis(P=0.008), pyrimidine metabolism(P=0.014), pantothenate and CoA biosynthesis(P=0.022), valine, leucine and isoleucine biosynthesis(P=0.022), lysine biosynthesis(P=0.031), glycerolipid metabolism(P=0.046), and valine, leucine and isoleucine degradation(P=0.031). Almost all the metabolites decreased except for the glyceric acid exhibiting a higher content in the VLBW premature infant. 12 potential biomarkers were explored with the most significant covariance and correlation, within which stearic acid, palmiticacid, myristic acid, β-amino-isobutyric acid, and uric acid were lower, while myo-inositol, mannitol, glycine, glucose1, glucose2, glyceric

  1. Nitrate reduction in a groundwater microcosm determined by sup 15 N gas chromatography-mass spectrometry

    SciTech Connect

    Bengtsson, G.; Annadotter, H. )

    1989-11-01

    Aerobic and anaerobic groundwater continuous-flow microcosms were designed to study nitrate reduction by the indigenous bacteria in intact saturated soil cores from a sandy aquifer with a concentration of 3.8 mg of NO{sub 3}{sup {minus}}-N liter{sup {minus}1}. Traces of {sup 15}NO{sub 3}{sup {minus}} were added to filter-sterilized groundwater by using a Darcy flux of 4 cm day{sup {minus}1}. Both assimilatory and dissimilatory reduction rates were estimated from analyses of {sup 15}N{sub 2}, {sup 15}N{sub 2}O, {sup 15}NH{sub 4}{sup +}, and {sup 15}N-labeled protein amino acids by capillary gas chromatography-mass spectrometry. N{sub 2} and N{sub 2}O were separated on a megabore fused-silica column and quantified by electron impact-selected ion monitoring. NO{sub 3}{sup {minus}} and NH{sub 4}{sup +} were analyzed as pentafluorobenzoyl amides by multiple-ion monitoring and protein amino acids as their N-heptafluorobutyryl isobutyl ester derivatives by negative ion-chemical ionization. The numbers of bacteria and their (methyl-{sup 3}H)thymidine incorporation rates were simultaneously measured. Nitrate was completely reduced in the microcosms at a rate of about 250 ng g{sup {minus}1} day{sup {minus}1}. Of this nitrate, 80 to 90% was converted by aerobic denitrification to N{sub 2}, whereas only 35% was denitrified in the anaerobic microcosm, where more than 50% of NO{sub 3}{sup {minus}} was reduced to NH{sub 4}{sup +}. Assimilatory reduction was recorded only in the aerobic microcosm, where N appeared in alanine in the cells. The nitrate reduction rates estimated for the aquifer material were low in comparison with rates in eutrophic lakes and coastal sediments but sufficiently high to remove nitrate from an uncontaminated aquifer of the kind examined in less than 1 month.

  2. Simultaneous determination of urinary dialkylphosphate metabolites of organophosphorus pesticides using gas chromatography-mass spectrometry.

    PubMed

    Ueyama, Jun; Saito, Isao; Kamijima, Michihiro; Nakajima, Tamie; Gotoh, Masahiro; Suzuki, Takayoshi; Shibata, Eiji; Kondo, Takaaki; Takagi, Kenji; Miyamoto, Ken-ichi; Takamatsu, Junki; Hasegawa, Takaaki; Takagi, Kenzo

    2006-02-17

    In this study, we developed a safe and sensitive method for the simultaneous determination of urinary dialkylphosphates (DAPs), metabolites of organophosphorus insecticides (OPs), including dimethylphosphate (DMP), diethylphosphate (DEP), dimethylthiophosphate (DMTP), and diethylthiophosphate (DETP), using a pentafluorobenzylbromide (PFBBr) derivatization and gas chromatography-mass spectrometry (GC-MS). Several parameters were investigated: pH on evaporation, reaction temperature and time for the derivatization, the use of an antioxidant for preventing oxidation, and a clean-up step. The pH was set at 6, adjusted with K2CO3, and the reaction temperature and time of derivatization were 80 degrees C and 30 min, respectively. Sodium disulfite was chosen as an antioxidant. The clean-up step was performed with a Florisil/PSE mini-column to remove the unreacted PFBBr and sample matrix. This established procedure markedly shortened the sample preparation time to only about 3 h, and completely inhibited the unwanted oxidization of dialkylthiophosphates. The limits of determination (LOD) were approximately 0.3 microg/L for DMP, and 0.1 microg/L for DEP, DMTP, and DETP in 5 mL of human urine. Within-series and between-day imprecision for the present method using pooled urine spiked with DAPs was less than 20.6% in the calibration range of 1-300 microg/L, and the mean recovery was 56.7-60.5% for DMP, 78.5-82.7% for DEP, 88.3-103.9% for DMTP, and 84.2-92.4% for DETP. This method detected geometric mean values of the urinary DAPs in Japanese with and without occupational exposure to OPs, 16.6 or 27.4 for DMP, 1.0 or 0.7 for DEP, 1.3 or 2.3 for DMTP, and 1.0 or 1.1 microg/L for DETP, respectively. The present method, which does not require special equipment except for GC-MS, is quick, safe, and sensitive enough to be adopted in routine biological monitoring of non-occupational as well as occupational exposure to OPs.

  3. Authentication of Organically and Conventionally Grown Basils by Gas Chromatography/Mass Spectrometry Chemical Profiles

    PubMed Central

    Wang, Zhengfang; Chen, Pei; Yu, Liangli; Harrington, Peter de B.

    2013-01-01

    Basil plants cultivated by organic and conventional farming practices were accurately classified by pattern recognition of gas chromatography/mass spectrometry (GC/MS) data. A novel extraction procedure was devised to extract characteristic compounds from ground basil powders. Two in-house fuzzy classifiers, i.e., the fuzzy rule-building expert system (FuRES) and the fuzzy optimal associative memory (FOAM) for the first time, were used to build classification models. Two crisp classifiers, i.e., soft independent modeling by class analogy (SIMCA) and the partial least-squares discriminant analysis (PLS-DA), were used as control methods. Prior to data processing, baseline correction and retention time alignment were performed. Classifiers were built with the two-way data sets, the total ion chromatogram representation of data sets, and the total mass spectrum representation of data sets, separately. Bootstrapped Latin partition (BLP) was used as an unbiased evaluation of the classifiers. By using two-way data sets, average classification rates with FuRES, FOAM, SIMCA, and PLS-DA were 100 ± 0%, 94.4 ± 0.4%, 93.3 ± 0.4%, and 100 ± 0%, respectively, for 100 independent evaluations. The established classifiers were used to classify a new validation set collected 2.5 months later with no parametric changes except that the training set and validation set were individually mean-centered. For the new two-way validation set, classification rates with FuRES, FOAM, SIMCA, and PLS-DA were 100%, 83%, 97%, and 100%, respectively. Thereby, the GC/MS analysis was demonstrated as a viable approach for organic basil authentication. It is the first time that a FOAM has been applied to classification. A novel baseline correction method was used also for the first time. The FuRES and the FOAM are demonstrated as powerful tools for modeling and classifying GC/MS data of complex samples and the data pretreatments are demonstrated to be useful to improve the performance of classifiers

  4. Headspace solid-phase microextraction-gas chromatography-mass spectrometry characterization of propolis volatile compounds.

    PubMed

    Pellati, Federica; Prencipe, Francesco Pio; Benvenuti, Stefania

    2013-10-01

    In this study, a novel and efficient method based on headspace solid-phase microextraction (HS-SPME), followed by gas chromatography-mass spectrometry (GC-MS), was developed for the analysis of propolis volatile compounds. The HS-SPME procedure, whose experimental parameters were properly optimized, was carried out using a 100 μm polydimethylsiloxane (PDMS) fiber. The GC-MS analyses were performed on a HP-5 MS cross-linked 5% diphenyl-95% dimethyl polysiloxane capillary column (30 m × 0.25 mm I.D., 1.00 μm film thickness), under programmed-temperature elution. Ninety-nine constituents were identified using this technique in the samples of raw propolis collected from different Italian regions. The main compounds detected include benzoic acid (0.87-30.13%) and its esters, such as benzyl benzoate (0.16-13.05%), benzyl salicylate (0.34-1.90%) and benzyl cinnamate (0.34-3.20%). Vanillin was detected in most of the samples analyzed in this study (0.07-5.44%). Another relevant class of volatile constituents is represented by sesquiterpene hydrocarbons, such as δ-cadinene (1.29-13.31%), γ-cadinene (1.36-8.85%) and α-muurolene (0.78-6.59%), and oxygenated sesquiterpenes, such as β-eudesmol (2.33-12.83%), T-cadinol (2.73-9.95%) and α-cadinol (4.84-9.74%). Regarding monoterpene hydrocarbons, they were found to be present at low level in the samples analyzed in this study, with the exception of one sample from Southern Italy, where α-pinene was the most abundant constituent (13.19%). The results obtained by HS-SPME-GC-MS were also compared with those of hydrodistillation (HD) coupled with GC-MS. The HS-SPME-GC-MS method developed in this study allowed us to determine the chemical fingerprint of propolis volatile constituents, thus providing a new and reliable tool for the complete characterization of this biologically active apiary product.

  5. Correlation of Drug-Testing Results - Immunoassay versus Gas Chromatography-Mass Spectrometry.

    PubMed

    Huang, M H; Liu, R H; Chen, Y L; Rhodes, S L

    2006-01-01

    The need for and prevalence of workplace drug-testing programs mandate the development of an effective and efficient two-step test strategy. Successful implementation of the two-step test strategy relies on the establishment of a reasonable correlation between the preliminary and the confirmatory test data and the selection of an appropriate cutoff for each test step. Correlations of test data derived form these two test steps were most commonly studied qualitatively by comparing the positive/negative test result concluded by these two test steps; however, when instrument-based immunoassays (IA) are used in the preliminary test step, the resulting "semiquantitative" and "apparent" concentration of the targeted analyte can be quantitatively correlated to the analyte concentration as determined by gas chromatography-mass spectrometry (GC-MS). Specimens selected for quantitative correlation studies should be clinical specimens with the distributions of metabolites similar to that present in test specimens; if the resulting correlation data are to be used for selecting appropriate/corresponding cutoffs for these two test steps, the concentrations of the targeted analyte in these specimens should also be within a narrow range centering on the proposed GC-MS cutoff concentration. Among the very significant number of reports correlating IA and GC-MS test data, cannabis and urine are the most common drug category and test specimen studied. The degree of correlation between IA and the GC-MS test data varies with the IA reagent manufacturers, and even with manufacture dates/lots of those supplied by the same manufacturer. The most important factors underlying the observed degree of correlation are undoubtedly the cross-reacting characteristics of the antibody and the metabolite distribution pattern of the drug of concern. Over time, specificities of IA reagents have been optimized so that the two-step test strategy can be most effectively and efficiently applied using the

  6. Plasma metabolomic profiling of dairy cows affected with ketosis using gas chromatography/mass spectrometry

    PubMed Central

    2013-01-01

    Background Ketosis is an important problem for dairy cows` production performance. However, it is still little known about plasma metabolomics details of dairy ketosis. Results A gas chromatography/mass spectrometry (GC/MS) technique was used to investigate plasma metabolic differences in cows that had clinical ketosis (CK, n=22), subclinical ketosis (SK, n=32), or were clinically normal controls (NC, n=22). The endogenous plasma metabolome was measured by chemical derivatization followed by GC/MS, which led to the detection of 267 variables. A two-sample t-test of 30, 32, and 13 metabolites showed statistically significant differences between SK and NC, CK and NC, and CK and SK, respectively. Orthogonal signal correction-partial least-square discriminant analysis (OPLS-DA) revealed that the metabolic patterns of both CK and SK were mostly similar, with the exception of a few differences. The development of CK and SK involved disturbances in many metabolic pathways, mainly including fatty acid metabolism, amino acid metabolism, glycolysis, gluconeogenesis, and the pentose phosphate pathway. A diagnostic model arbitrary two groups was constructed using OPLS-DA and receiver–operator characteristic curves (ROC). Multivariate statistical diagnostics yielded the 19 potential biomarkers for SK and NC, 31 for CK and NC, and 8 for CK and SK with area under the curve (AUC) values. Our results showed the potential biomarkers from CK, SK, and NC, including carbohydrates, fatty acids, amino acids, even sitosterol and vitamin E isomers, etc. 2-piperidinecarboxylic acid and cis-9-hexadecenoic acid were closely associated with metabolic perturbations in ketosis as Glc, BHBA and NEFA for dealing with metabolic disturbances of ketosis in clinical practice. However, further research is needed to explain changes of 2,3,4-trihydroxybutyric acid, 3,4-dihydroxybutyric acid, α-aminobutyric acid, methylmalonic acid, sitosterol and α-tocopherol in CK and SK, and to reveal differences

  7. Analytical strategies for characterizing organic paint media using gas chromatography/mass spectrometry.

    PubMed

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

    2010-06-15

    Throughout history, artists have experimented with a variety of organic-based natural materials, using them as paint binders, varnishes, and ingredients for mordants in gildings. Artists often use many layers of paint to produce particular effects. How we see a painting is thus the final result of how this complex, highly heterogeneous, multimaterial, and multilayered structure interacts with light. The chemical characterization of the organic substances in paint materials is of great importance for artwork conservation because the organic components of the paint layers are particularly subject to degradation. In addition, understanding the organic content and makeup of paint materials allows us to differentiate between the painting techniques that have been used over history. Applying gas chromatography/mass spectrometry (GC/MS) analysis to microsamples of paint layers is widely recognized as the best approach for identifying organic materials, such as proteins, drying oils, waxes, terpenic resins, and polysaccharide gums. The method provides essential information for reconstructing artistic techniques, assessing the best conditions for long-term preservation, and planning restoration. In this Account, we summarize the more common approaches adopted in the study of the organic components of paint materials. Our progress in developing GC/MS analytical procedures in the field of cultural heritage is presented, focusing on problems that arise from (i) the presence of mixtures of many chemically complex and degraded materials, (ii) the interference of inorganic species, (iii) the small size of the samples, and (iv) the risk of contamination. We outline some critical aspects of the analytical strategy, such as the need to optimize specific wet-chemical sample pretreatments in order to separate the various components, hydrolyze macromolecular analytes, clean-up inorganic ions, and derivatize polar molecules for subsequent GC/MS separation and identification. We also

  8. Analysis of paralytic shellfish toxins using high-field asymmetric waveform ion mobility spectrometry with liquid chromatography-mass spectrometry.

    PubMed

    Beach, Daniel G; Melanson, Jeremy E; Purves, Randy W

    2015-03-01

    The analysis of paralytic shellfish toxins (PSTs) by liquid chromatography-mass spectrometry remains a challenge because of their high polarity, large number of analogues and the complex matrix in which they occur. Here we investigate the potential utility of high-field asymmetric waveform ion mobility spectrometry (FAIMS) as a gas-phase ion separation tool for analysis of PSTs by mass spectrometry. We investigate the separation of PSTs using FAIMS with two divergent goals: using FAIMS as a primary separation tool for rapid screening by electrospray ionization (ESI)-FAIMS-MS or combined with LC in a multidimensional LC-ESI-FAIMS-MS separation. First, a survey of the parameters that affect the sensitivity and selectivity of PST analysis by FAIMS was carried out using ESI-FAIMS-MS. In particular, the use of acetonitrile as a gas additive in the carrier gas flow offered good separation of all PST epimeric pairs. A second set of FAIMS conditions was also identified, which focussed PSTs to a relatively narrow CV range allowing development of an LC-ESI-FAIMS-MS method for analysis of PST toxins in complex mussel tissue extracts. The quantitative capabilities of this method were evaluated by analysing a PST containing mussel tissue matrix material. Results compared favourably with analysis by an established LC-post-column oxidation-fluorescence method with recoveries ranging from 70 to 106%, although sensitivity was somewhat reduced. The current work represents the first successful separation of PST isomers using ion mobility and shows the promise of FAIMS as a tool for analysis of algal biotoxins in complex samples and outlines some critical requirements for its future improvement.

  9. The use of stable isotopes and gas chromatography/mass spectrometry in the identification of steroid metabolites in the equine

    SciTech Connect

    Houghton, E.; Dumasia, M.C.; Teale, P.; Smith, S.J.; Cox, J.; Marshall, D.; Gower, D.B. )

    1990-10-01

    Stable isotope gas chromatography/mass spectrometry has been used successfully in the elucidation of structures of urinary steroid metabolites in the horse and in the identification of metabolites isolated from in vivo perfusion and in vitro incubation studies using equine tissue preparations. Deuterium-labeled steroids, testosterone, dehydroepiandrosterone, and 5-androstene-3 beta,17 beta-diol have been synthesized by base-catalyzed isotope exchange methods and the products characterized by gas chromatography/mass spectrometry. (16,16(-2)H2)Dehydroepiandrosterone (plus radiolabeled dehydroepiandrosterone) was perfused into a testicular artery of a pony stallion and was shown to be metabolized into 2H2-labeled testosterone, 4-androstenedione, isomers of 5-androstene-3,17-diol, 19-hydroxytestosterone, and 19-hydroxy-4-androstenedione. In further studies, equine testicular minces have been incubated with 2H2-labeled and radiolabeled dehydroepiandrosterone and 5-androstene-3 beta, 17 beta-diol. The metabolites, whose identity was confirmed by stable isotope gas chromatography/mass spectrometry, proved the interconversion of the two substrates, as well as formation of testosterone and 4-androstenedione. The aromatization of dehydroepiandrosterone was also confirmed, together with the formation of an isomer of 5(10)-estrene-3,17-diol from both substrates showing 19-demethylation without concomitant aromatization. In studies of the feto-placental unit, the allantochorion was shown to aromatize (2H5)testosterone to (2H4)estradiol, the loss of one 2H from the substrate being consistent with aromatization of the A ring. The formation of 6-hydroxyestradiol was also confirmed in this study. The same technique has been valuable in determining the structure of two metabolites of nandrolone isolated from horse urine.

  10. Profiling degradants of paclitaxel using liquid chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry substructural techniques.

    PubMed

    Volk, K J; Hill, S E; Kerns, E H; Lee, M S

    1997-08-15

    A rapid and systematic strategy based on liquid chromatography-mass spectrometry (LC-MS) profiling and liquid chromatography-tandem mass spectrometry (LC-MS-MS) substructural techniques was utilized to elucidate the degradation products of paclitaxel, the active ingredient in Taxol. This strategy integrates, in a single instrumental approach, analytical HPLC, UV detection, full-scan electrospray MS, and MS-MS to rapidly and accurately elucidate structures of impurities and degradants. In these studies, degradants induced by acid, base, peroxide, and light were profiled using LC-MS and LC-MS-MS methodologies resulting in an LC-MS degradant database which includes information on molecular structures, chromatographic behavior, molecular mass, and MS-MS substructural information. The stressing conditions which may cause drug degradation are utilized to validate the analytical monitoring methods and serve as predictive tools for future formulation and packaging studies. Degradation products formed upon exposure to basic conditions included baccatin III, paclitaxel sidechain methyl ester, 10-deacetylpaclitaxel, and 7-epipaclitaxel. Degradation products formed upon exposure to acidic conditions included 10-deacetylpaclitaxel and the oxetane ring opened product. Treatment with hydrogen peroxide produced only 10-deacetylpaclitaxel. Exposure to high intensity ligh produced a number of degradants. The most abundant photodegradant of paclitaxel corresponded to an isomer which contains a C3-C11 bridge. These methodologies are applicable at any stage of the drug product cycle from discovery through development. This library of paclitaxel degradants provides a foundation for future development work regarding product monitoring, as well as use as a diagnostic tool for new degradation products.

  11. The composition of volatile components in olivines from Yakutian kimberlites of various ages: Evidence from gas chromatography-mass spectrometry

    NASA Astrophysics Data System (ADS)

    Tomilenko, A. A.; Bul'bak, T. A.; Khomenko, M. O.; Kuzmin, D. V.; Sobolev, N. V.

    2016-06-01

    The composition of volatiles from fluid and melt inclusions in olivine phenocrysts from Yakutian kimberlite pipes of various ages (Olivinovaya, Malokuonapskaya, and Udachnaya-East) were studied for the first time by gas chromatography-mass spectrometry. It was shown that hydrocarbons and their derivatives, as well as nitrogen-, halogen-, and sulfur-bearing compounds, played a significant role in the mineral formation. The proportion of hydrocarbons and their derivatives in the composition of mantle fluids could reach 99%, including up to 4.9% of chlorineand fluorine-bearing compounds.

  12. Identification of Gibberellins in Norway Spruce (Picea abies [L.] Karst.) by Combined Gas Chromatography-Mass Spectrometry

    PubMed Central

    Odén, Per Christer; Schwenen, Ludger; Graebe, Jan E.

    1987-01-01

    Gibberellins A1 (GA1), A3 and A9 were identified from extracts of shoots of 6-month old Norway spruce (Picea abies) seedlings by the use of sequential reverse and normal phase high performance liquid chromatography (HPLC), bioassay, radioimmunoassay (RIA) and combined gas chromatography-mass spectrometry (GC-MS). The bioassay and RIA were used after fractionation by HPLC to detect the GA-containing fractions, which were then examined by GC-MS. The GAs identified are considered to be endogenous. PMID:16665471

  13. Application of capillary gas chromatography mass spectrometry/computer techniques to synoptic survey of organic material in bed sediment

    USGS Publications Warehouse

    Steinheimer, T.R.; Pereira, W.E.; Johnson, S.M.

    1981-01-01

    A bed sediment sample taken from an area impacted by heavy industrial activity was analyzed for organic compounds of environmental significance. Extraction was effected on a Soxhlet apparatus using a freeze-dried sample. The Soxhlet extract was fractionated by silica gel micro-column adsorption chromatography. Separation and identification of the organic compounds was accomplished by capillary gas chromatography/mass spectrometry techniques. More than 50 compounds were identified; these include saturated hydrocarbons, olefins, aromatic hydrocarbons, alkylated polycyclic aromatic hydrocarbons, and oxygenated compounds such as aldehydes and ketones. The role of bed sediments as a source or sink for organic pollutants is discussed. ?? 1981.

  14. Chemical analysis of surface hydrocarbons in fireflies by direct contact extraction and gas chromatography-mass spectrometry.

    PubMed

    Shibue, Keiko; Goto, Yoshimasa; Kawashima, Itsuro; Shibue, Toshimichi

    2004-12-01

    We characterized three Japanese firefly species (Luciola lateralis, Luciola cruciata, and Lucidina biplagiata) and three North American firefly species (Lucidota atra, Photuris lucicrescens, and Photuris cinctipennis) based on their surface hydrocarbons. The analysis of firefly extracts by gas chromatography-mass spectrometry (GC-MS) revealed clear differences in the chromatographic profiles and mass spectra. Each firefly could be distinguished by its GC-MS profile. A major difference was observed between Japanese fireflies and North American fireflies. Among the North American fireflies, non-luminous fireflies, Lucidota atra, showed much more complicated GC-MS profile than those of luminous fireflies, Photuris lucicrescens and Photuris cinctipennis.

  15. Detection of perfluorocarbons in blood by headspace solid-phase microextraction combined with gas chromatography/mass spectrometry.

    PubMed

    Mathurin, J C; de Ceaurriz, J; Audran, M; Krafft, M P

    2001-11-01

    A new method of detection of perfluorocarbon molecules (PFCs) in blood sample has been established. After an extraction and pre-concentration step performed by headspace solid-phase microextraction (HS-SPME), the PFCs are detected by gas chromatography-mass spectrometry (GC/MS) with an ion trap mass spectrometer in MS and MS/MS modes. The influence of different parameters on the SPME process is discussed. The limit of detection and the linearity of the procedure have been determined for two PFCs.

  16. Simultaneous identification of 18 illegal adulterants in dietary supplements by using high-performance liquid chromatography-mass spectrometry.

    PubMed

    Tagami, Takaomi; Aoyama, Airin; Takeda, Akihiro; Asada, Akiko; Doi, Takahiro; Kajimura, Keiji; Sawabe, Yoshiyuki

    2014-01-01

    We developed a method for the identification of 18 illegal adulterants in dietary supplements for erectile dysfunction by using high-performance liquid chromatography-mass spectrometry. The separation was achieved on a Cosmosil 3C18-EB column. The mobile phase consisted of 0.1% formic acid solution and 0.1% formic acid in acetonitrile, with gradient elution at a flow rate of 0.15 mL/min. The proposed method may be useful for the identification of illegal adulterants and for quality control of dietary supplements.

  17. Determination of cocaine and cocaethylene in plasma by solid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Alvarez, Iván; Bermejo, Ana María; Tabernero, María Jesús; Fernández, Purificación; López, Patricia

    2007-01-01

    The present paper describes a method for the simultaneous determination of cocaine and cocaethylene in plasma. It was based in the extraction of the analytes by solid-phase microextraction (SPME), and gas chromatography-mass spectrometry (GC-MS) was used to identify and quantify the analytes in selected ion monitoring (SIM) mode. The method showed to be very simple, rapid and sensitive. The method was validated for the two compounds, including linearity (range 25-1000 ng/mL) and the main precision parameters. It was applied to ten plasma samples from cocaine and alcohol users, obtaining positive results in all cases.

  18. Multiclass mycotoxin analysis in food, environmental and biological matrices with chromatography/mass spectrometry.

    PubMed

    Capriotti, Anna Laura; Caruso, Giuseppe; Cavaliere, Chiara; Foglia, Patrizia; Samperi, Roberto; Laganà, Aldo

    2012-01-01

    Mold metabolites that can elicit deleterious effects on other organisms are classified as mycotoxins. Human exposure to mycotoxins occurs mostly through the intake of contaminated agricultural products or residues due to carry over or metabolite products in foods of animal origin such as milk and eggs, but can also occur by dermal contact and inhalation. Mycotoxins contained in moldy foods, but also in damp interiors, can cause diseases in humans and animals. Nephropathy, various types of cancer, alimentary toxic aleukia, hepatic diseases, various hemorrhagic syndromes, and immune and neurological disorders are the most common diseases that can be related to mycotoxicosis. The absence or presence of mold infestation and its propagation are seldom correlated with mycotoxin presence. Mycotoxins must be determined directly, and suitable analytical methods are necessary. Hundreds of mycotoxins have been recognized, but only for a few of them, and in a restricted number of utilities, a maximum acceptable level has been regulated by law. However, mycotoxins seldom develop alone; more often various types and/or classes form in the same substrate. The co-occurrence might render the individual mycotoxin tolerance dose irrelevant, and therefore the mere presence of multiple mycotoxins should be considered a risk factor. The advantage of chromatography/mass spectrometry (MS) is that many compounds can be determined and confirmed in one analysis. This review illustrates the state-of-the-art of mycotoxin MS-based analytical methods for multiclass, multianalyte determination in all the matrices in which they appear. A chapter is devoted to the history of the long-standing coexistence and interaction among humans, domestic animals and mycotoxicosis, and the history of the discovery of mycotoxins. Quality assurance, although this topic relates to analytical chemistry in general, has been also examined for mycotoxin analysis as a preliminary to the systematic literature excursus

  19. Predicting percent composition of blends of biodiesel and conventional diesel using gas chromatography-mass spectrometry, comprehensive two-dimensional gas chromatography-mass spectrometry, and partial least squares analysis.

    PubMed

    Pierce, Karisa M; Schale, Stephen P

    2011-01-30

    The percent composition of blends of biodiesel and conventional diesel from a variety of retail sources were modeled and predicted using partial least squares (PLS) analysis applied to gas chromatography-total-ion-current mass spectrometry (GC-TIC), gas chromatography-mass spectrometry (GC-MS), comprehensive two-dimensional gas chromatography-total-ion-current mass spectrometry (GCxGC-TIC) and comprehensive two-dimensional gas chromatography-mass spectrometry (GCxGC-MS) separations of the blends. In all four cases, the PLS predictions for a test set of chromatograms were plotted versus the actual blend percent composition. The GC-TIC plot produced a best-fit line with slope=0.773 and y-intercept=2.89, and the average percent error of prediction was 12.0%. The GC-MS plot produced a best-fit line with slope=0.864 and y-intercept=1.72, and the average percent error of prediction was improved to 6.89%. The GCxGC-TIC plot produced a best-fit line with slope=0.983 and y-intercept=0.680, and the average percent error was slightly improved to 6.16%. The GCxGC-MS plot produced a best-fit line with slope=0.980 and y-intercept=0.620, and the average percent error was 6.12%. The GCxGC models performed best presumably due to the multidimensional advantage of higher dimensional instrumentation providing more chemical selectivity. All the PLS models used 3 latent variables. The chemical components that differentiate the blend percent compositions are reported. Copyright © 2010 Elsevier B.V. All rights reserved.

  20. Isotope ratio monitoring gas chromatography/Mass spectrometry of D/H by high temperature conversion isotope ratio mass spectrometry.

    PubMed

    Hilkert; Douthitt; Schlüter; Brand

    1999-07-01

    Of all the elements, hydrogen has the largest naturally occurring variations in the ratio of its stable isotopes (D/H). It is for this reason that there has been a strong desire to add hydrogen to the list of elements amenable to isotope ratio monitoring gas chromatography/mass spectrometry (irm-GC/MS). In irm-GC/MS the sample is entrained in helium as the carrier gas, which is also ionized and separated in the isotope ratio mass spectrometer (IRMS). Because of the low abundance of deuterium in nature, precise and accurate on-line monitoring of D/H ratios with an IRMS requires that low energy helium ions be kept out of the m/z 3 collector, which requires the use of an energy filter. A clean mass 3 (HD(+.)) signal which is independent of a large helium load in the electron impact ion source is essential in order to reach the sensitivity required for D/H analysis of capillary GC peaks. A new IRMS system, the DELTA(plus)XL(trade mark), has been designed for high precision, high accuracy measurements of transient signals of hydrogen gas. It incorporates a retardation lens integrated into the m/z 3 Faraday cup collector. Following GC separation, the hydrogen bound in organic compounds must be quantitatively converted into H(2) gas prior to analysis in the IRMS. Quantitative conversion is achieved by high temperature conversion (TC) at temperatures >1400 degrees C. Measurements of D/H ratios of individual organic compounds in complicated natural mixtures can now be made to a precision of 2 per thousand (delta notation) or, better, with typical sample amounts of approximately 200 ng per compound. Initial applications have focused on compounds of interest to petroleum research (biomarkers and natural gas components), food and flavor control (vanillin and ethanol), and metabolic studies (fatty acids and steroids). Copyright 1999 John Wiley & Sons, Ltd.

  1. Thermal desorption-gas chromatography-mass spectrometry method to determine phthalate and organophosphate esters from air samples.

    PubMed

    Aragón, M; Borrull, F; Marcé, R M

    2013-08-16

    A method based on thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) has been developed to determine four organophosphate esters, seven phthalate esters, and bis(2-ethylhexyl) adipate in the gas phase from harbour and urban air samples. The method involves the sampling of 1.5L of air in a Tenax TA sorbent tube followed by thermal desorption (using a Tenax TA cryogenic trap) coupled to gas chromatography-mass spectrometry. The repeatability of the method expressed as %RSD (n=3) is less than 15% and the MQLs are between 0.007μgm(-3) (DMP, TBP, BBP, TPP and DnOP) and 6.7μgm(-3) (DEHP). The method was successfully applied in two areas (urban and harbour) testing two and three points in each one, respectively. Some of these compounds were found in both urban and harbour samples. Di-(2-ethylhexyl)phthalate was the most abundant compound found in both areas at concentration levels between 6.7μgm(-3) and 136.4μgm(-3). This study demonstrates that thermal desorption is an efficient method for the determination of these semi-volatile compounds in the gas phase fraction of air samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Chromatographic fingerprint analysis of metabolites in natural and artificial agarwood using gas chromatography-mass spectrometry combined with chemometric methods.

    PubMed

    Gao, Xiaoxia; Xie, Mingrong; Liu, Shaofeng; Guo, Xiaoling; Chen, Xiaoying; Zhong, Zhaojian; Wang, Lei; Zhang, Weimin

    2014-09-15

    Agarwood is a resinous material formed in wounded Aquilaria sinensis in China, which is widely used as an effective traditional Chinese medicine (TCM). This study is aimed to use gas chromatography-mass spectrometry combined with chemometric methods to create reliable criteria for accurate identification of natural agarwood and artificial agarwood, as well as for quality evaluation of artificial agarwood. Natural agarwood and artificial agarwood (stimulated by formic acid or formic acid plus fungal inoculation) were used as standards and controls for the gas chromatography-mass spectrometry (GC-MS) and multivariate analysis. The identification criteria developed were applied to commercial agarwood. A reliable criteria including correlation coefficient of GC-MS fingerprint of natural agarwood and 22 markers of metabolism in natural and artificial agarwood was constructed. Compared with chemically stimulated agarwood (formic acid) and in terms of the 22 markers, artificial agarwood obtained by formic acid stimulation and fungal inoculation were much closer to natural agarwood. The study demonstrates that the chemical components of artificial agarwood obtained by comprehensive stimulated method (formic acid plus fungal inoculation) are much closer to the natural agarwood than those obtained by chemically stimulated method (formic acid), as times goes by. A reliable criteria containing correlation coefficient of GC-MS fingerprint of natural agarwood and 22 metabolism markers can be used to evaluate the quality of the agarwood. As an application case, three samples were identified as natural agarwood from the 25 commercial agarwood by using the evaluation method.

  3. Potential of needle trap microextraction-portable gas chromatography-mass spectrometry for measurement of atmospheric volatile compounds

    NASA Astrophysics Data System (ADS)

    Feijó Barreira, Luís Miguel; Xue, Yu; Duporté, Geoffroy; Parshintsev, Jevgeni; Hartonen, Kari; Jussila, Matti; Kulmala, Markku; Riekkola, Marja-Liisa

    2016-08-01

    Volatile organic compounds (VOCs) play a key role in atmospheric chemistry and physics. They participate in photochemical reactions in the atmosphere, which have direct implications on climate through, e.g. aerosol particle formation. Forests are important sources of VOCs, and the limited resources and infrastructures often found in many remote environments call for the development of portable devices. In this research, the potential of needle trap microextraction and portable gas chromatography-mass spectrometry for the study of VOCs at forest site was evaluated. Measurements were performed in summer and autumn 2014 at the Station for Measuring Ecosystem-Atmosphere Relations (SMEAR II) in Hyytiälä, Finland. During the first part of the campaign (summer) the applicability of the developed method was tested for the determination of monoterpenes, pinonaldehyde, aldehydes, amines and anthropogenic compounds. The temporal variation of aerosol precursors was determined, and evaluated against temperature and aerosol number concentration data. The most abundant monoterpenes, pinonaldehyde and aldehydes were successfully measured, their relative amounts being lower during days when particle number concentration was higher. Ethylbenzene, p- and m-xylene were also found when wind direction was from cities with substantial anthropogenic activity. An accumulation of VOCs in the snow cover was observed in the autumn campaign. Results demonstrated the successful applicability of needle trap microextraction and portable gas chromatography-mass spectrometry for the rapid in situ determination of organic gaseous compounds in the atmosphere.

  4. Sensitive determination of methomyl in blood using gas chromatography-mass spectrometry as its oxime tert.-butyldimethylsilyl derivative.

    PubMed

    Ito, S; Kudo, K; Imamura, T; Suzuki, T; Ikeda, N

    1998-08-25

    A sensitive, selective and reliable method was developed to determine methomyl ¿methyl-N-[(methylcarbamoyl)oxy]-thioacetimidate¿, a carbamate insecticide in human blood, using gas chromatography-mass spectrometry. Dimethylglyoxime served as an internal standard (I.S.). Methomyl in the blood was converted to its oxime form by sodium hydroxide. The solution made acidic with hydrochloric acid was poured into a column packed with Extrelut. Methomyloxime and I.S. were eluted from the column with a mixture of dichloromethane-ethyl acetate-chloroform (65:25:10), transformed to tert.-butyldimethylsilyl derivatives, and analyzed by gas chromatography-mass spectrometry in the electron impact mode. The calibration curves were linear in the concentration range from 1 ng/g to 100 ng/g and 100 ng/g to at least 5000 ng/g. The lower limit of detection was 0.5 ng/g. The absolute recoveries were 72-93% and within-day coefficients of variation were 3.1-5.6% at blood concentrations of 10 and 1000 ng/g. Two practical forensic applications are described.

  5. Interference of 3-hydroxyisobutyrate with measurements of ketone body concentration and isotopic enrichment by gas chromatography-mass spectrometry.

    PubMed

    Des Rosiers, C; Montgomery, J A; Desrochers, S; Garneau, M; David, F; Mamer, O A; Brunengraber, H

    1988-08-15

    Concentrations and 13C2 molar percentage enrichments of blood R-3-hydroxybutyrate and acetoacetate are measured by selected ion monitoring gas chromatography-mass spectrometry. Samples are treated with NaB2H4 to reduce unlabeled and labeled acetoacetate to corresponding deuterium-labeled RS-3-hydroxybutyrate species. Only the gas chromatographic peak for the tert-butyldimethylsilyl derivative of 3-hydroxybutyrate needs to be monitored. The various compounds are quantitated using an internal standard of RS-3-hydroxy-[2,2,3,4,4,4-2H6]-butyrate. Concentrations of ketone bodies are obtained by monitoring the m/z 159 to 163 fragments of tert-butyldimethylsilyl derivatives of labeled and unlabeled 3-hydroxybutyrate species. High correlations were obtained between ketone body concentrations assayed (i) enzymatically with R-3-hydroxybutyrate dehydrogenase and (ii) by gas chromatography-mass spectrometry. The limit of detection is about 10 nmol of substrate in blood samples. The current practice of monitoring the m/z 275 to 281 fragments overestimates the concentration of endogenous R-3-hydroxybutyrate, due to co-elution of 3-hydroxyisobutyrate, a valine metabolite. The method presented is used to measure ketone body turnover in vivo in 24-h-fasted dogs.

  6. High-temperature pyrolysis/gas chromatography/isotope ratio mass spectrometry: simultaneous measurement of the stable isotopes of oxygen and carbon in cellulose.

    PubMed

    Woodley, Ewan J; Loader, Neil J; McCarroll, Danny; Young, Giles H F; Robertson, Iain; Heaton, Timothy H E; Gagen, Mary H; Warham, Joseph O

    2012-01-30

    Stable isotope analysis of cellulose is an increasingly important aspect of ecological and palaeoenvironmental research. Since these techniques are very costly, any methodological development which can provide simultaneous measurement of stable carbon and oxygen isotope ratios in cellulose deserves further exploration. A large number (3074) of tree-ring α-cellulose samples are used to compare the stable carbon isotope ratios (δ(13)C) produced by high-temperature (1400°C) pyrolysis/gas chromatography (GC)/isotope ratio mass spectrometry (IRMS) with those produced by combustion GC/IRMS. Although the two data sets are very strongly correlated, the pyrolysis results display reduced variance and are strongly biased towards the mean. The low carbon isotope ratios of tree-ring cellulose during the last century, reflecting anthropogenic disturbance of atmospheric carbon dioxide, are thus overestimated. The likely explanation is that a proportion of the oxygen atoms are bonding with residual carbon in the reaction chamber to form carbon monoxide. The 'pyrolysis adjustment', proposed here, is based on combusting a stratified sub-sample of the pyrolysis results, across the full range of carbon isotope ratios, and using the paired results to define a regression equation that can be used to adjust all the pyrolysis measurements. In this study, subsamples of 30 combustion measurements produced adjusted chronologies statistically indistinguishable from those produced by combusting every sample. This methodology allows simultaneous measurement of the stable isotopes of carbon and oxygen using high-temperature pyrolysis, reducing the amount of sample required and the analytical costs of measuring them separately.

  7. Rapid and Accurate Identification of Animal Species in Natural Leather Goods by Liquid Chromatography/Mass Spectrometry.

    PubMed

    Izuchi, Yukari; Takashima, Tsuneo; Hatano, Naoya

    2016-01-01

    The demand for leather goods has grown globally in recent years. Industry revenue is forecast to reach $91.2 billion by 2018. There is an ongoing labelling problem in the leather items market, in that it is currently impossible to identify the species that a given piece of leather is derived from. To address this issue, we developed a rapid and simple method for the specific identification of leather derived from cattle, horses, pigs, sheep, goats, and deer by analysing peptides produced by the trypsin-digestion of proteins contained in leather goods using liquid chromatography/mass spectrometry. We determined species-specific amino acid sequences by liquid chromatography/tandem mass spectrometry analysis using the Mascot software program and demonstrated that collagen α-1(I), collagen α-2(I), and collagen α-1(III) from the dermal layer of the skin are particularly useful in species identification.

  8. Rapid and Accurate Identification of Animal Species in Natural Leather Goods by Liquid Chromatography/Mass Spectrometry

    PubMed Central

    Izuchi, Yukari; Takashima, Tsuneo; Hatano, Naoya

    2016-01-01

    The demand for leather goods has grown globally in recent years. Industry revenue is forecast to reach $91.2 billion by 2018. There is an ongoing labelling problem in the leather items market, in that it is currently impossible to identify the species that a given piece of leather is derived from. To address this issue, we developed a rapid and simple method for the specific identification of leather derived from cattle, horses, pigs, sheep, goats, and deer by analysing peptides produced by the trypsin-digestion of proteins contained in leather goods using liquid chromatography/mass spectrometry. We determined species-specific amino acid sequences by liquid chromatography/tandem mass spectrometry analysis using the Mascot software program and demonstrated that collagen α-1(I), collagen α-2(I), and collagen α-1(III) from the dermal layer of the skin are particularly useful in species identification. PMID:27313979

  9. [Differentiation of ballpoint pen inks by thermodesorption and gas chromatography-mass spectrometry].

    PubMed

    Bügler, Jürgen; Buchner, Hans; Dallmayer, Anton

    2004-01-01

    Differentiation and classification of ink entries with dated samples of a reference collection are important aspects in the examination of questioned documents. Classification of writing inks is presently achieved by analysis of dyes and colorants contained in the ink. This technique has its limitations in newly developed ink formulations with identical dye composition but differing in their solvents and binder resins. This paper introduces a method for the determination of solvents and binder resins of an ink sample directly from paper without sample preparation. This aim is accomplished by thermodesorption of the sample followed by gas chromatography/mass spectroscopy. The method was tested on numerous samples of ballpoint pen inks, which were subsequently grouped into several solvent and resin subgroups. A case study shows the applicability of the newly developed method.

  10. Quantitative Analysis and Fingerprint Profiles for Quality Control of Fructus Schisandrae by Gas Chromatography: Mass Spectrometry

    PubMed Central

    Xia, Yong-Gang; Yang, Bing-You; Liang, Jun; Yang, Qi; Wang, Di; Kuang, Hai-Xue

    2014-01-01

    This paper describes a simple, rapid, and effective quality assessment method for Fructus Schisandrae by gas chromatography-mass spectrum (GC-MS). The method was established by using specific lignan fingerprint profiles and quantitation of characteristic compounds in this herbal medicine. The GC-MS fingerprints of 15 batches of Schisandra samples from different regions of China showed similar lignan profiles. Five peaks were selected as characteristic peaks, and all of these were identified by using GC-MS techniques. The relative retention times of these characteristic peaks in the GC-MS fingerprint were established as an important parameter for identification of Schisandra samples. Meanwhile, relative peak areas may be a feasible approach to discriminate the S. chinensis and S. sphenanthera. Finally, these pharmacologically active constituents in the titled plant, schisandrins A–C and schizandrols A and B, were quantitatively determined using a validated GC-MS method. PMID:24574919

  11. Sensitive determination of fluoride in biological samples by gas chromatography-mass spectrometry after derivatization with 2-(bromomethyl)naphthalene.

    PubMed

    Kwon, Sun-Myung; Shin, Ho-Sang

    2014-12-10

    A gas chromatography-mass spectrometric method was developed in this study in order to determine fluoride in plasma and urine after derivatization with 2-(bromomethyl)naphthalene. 2-Fluoronaphthalene was chosen as the internal standard. The derivatization of fluoride was performed in the biological sample and the best reaction conditions (10.0 mg mL(-1) of 2-(bromomethyl)naphthalene, 1.0 mg mL(-1) of 15-crown-5-ether as a phase transfer catalyst, pH of 7.0, reaction temperature of 70°C, and heating time of 70 min) were established. The organic derivative was extracted with dichloromethane and then measured by a gas chromatography-mass spectrometry. Under the established condition, the detection limits were 11 μg L(-1) and 7 μg L(-1) by using 0.2 mL of plasma or urine, respectively. The accuracy was in a range of 100.8-107.6%, and the precision of the assay was less than 4.3% in plasma or urine. Fluoride was detected in a concentration range of 0.12-0.53 mg L(-1) in six urine samples after intake of natural mineral water containing 0.7 mg L(-1) of fluoride. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Vapor Pressure Determination of VM Using the Denunder-Liquid Chromatography-Mass Spectrometry Technique

    DTIC Science & Technology

    2015-01-01

    2012 – Sep 2012 4. TITLE AND SUBTITLE Vapor Pressure Determination of VM Using the Denuder– Liquid Chromatography–Mass Spectrometry Technique 5a... Liquid chromatography–mass spectrometry (LC–MS) Vapor pressure 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18. NUMBER OF...9 1 VAPOR PRESSURE DETERMINATION OF VM USING THE DENUDER– LIQUID CHROMATOGRAPHY–MASS SPECTROMETRY

  13. Solid-phase microcolumn extraction and gas chromatography-mass spectrometry identification of volatile organic compounds emitted by paper.

    PubMed

    Hrivnák, Ján; Tölgyessy, Peter; Figedyová, Sona; Katuscák, Svetozár

    2009-11-15

    A rapid non-destructive sampling technique for the analysis of volatile organic compounds (VOCs) emitted by paper sheets is described. A capillary, which is connected to a microcolumn packed with Tenax TA, is inserted between two sheets at the centre of a paper stack encapsulated inside a PET/Al/PE composite foil. The other end of the microcolumn is connected to a gas-tight syringe and an appropriate volume of gaseous phase is aspirated. The microcolumn is then thermally desorbed in a modified GC inlet (modification is presented) and analysed by gas chromatography-mass spectrometry (GC-MS). In the chromatogram from the analysis of artificially aged paper sample 21 compounds were identified. Advantages of the method including the short sampling time (1 min), simplicity and economic aspect are discussed.

  14. Determination of some volatile compounds in alcoholic beverage by headspace solid-phase microextraction gas chromatography - mass spectrometry

    NASA Astrophysics Data System (ADS)

    Schmutzer, G.; Avram, V.; Feher, I.; David, L.; Moldovan, Z.

    2012-02-01

    The volatile composition of alcoholic beverage was studied by headspace solid-phase microextraction (HSSPME) method and gas chromatography - mass spectrometry (GC-MS). Some volatile compounds, such as alcohols, esters, terpenes and other are mainly responsible for the flavor of fortified wines and their amounts specify the quality of the alcoholic beverages. From this perspective it is interesting to develop a rapid, selective and sensitive analytical method suitable for simultaneous quantification of the main molecules being responsible for the organoleptic characteristic of alcoholic beverages. Vermouth fortified drink was analyzed in order to characterize the volatile profile. Using the HS-SPME/GC-MS a number of twenty-six volatile compounds from a commercial market alcoholic beverage were identified. The most abundant compounds were m-thymol, o-thymol and eugenol, alongside of the ethyl ester compounds.

  15. A fatal case of trichlorofluoromethane (Freon 11) poisoning. Tissue distribution study by gas chromatography-mass spectrometry.

    PubMed

    Groppi, A; Polettini, A; Lunetta, P; Achille, G; Montagna, M

    1994-05-01

    A case of lethal poisoning due to trichlorofluoromethane (FC11) inhalation is described. The fluorocarbon was determined in biological tissues by headspace gas chromatography-mass spectrometry. FC11 was detected in all the examined tissues, with decreasing levels in heart, lung, brain, liver, blood, kidney, and spleen. The highest concentration measured in heart could be related to the mode of toxic action of fluorocarbons postulated by many authors, characterized by the sensitization of the myocardium to the catecholamines producing arrhythmia and cardiac arrest. Nevertheless the aspecific picture of the anatomo-pathological and histological findings does not exclude that the described accidental fatality may have been caused by the combination of direct from toxicity with hypoxemic asphyxiation, due to the saturation of the atmosphere by FC11 in the closed environment in which the intoxication occurred.

  16. The future of liquid chromatography-mass spectrometry (LC-MS) in metabolic profiling and metabolomic studies for biomarker discovery

    PubMed Central

    Metz, Thomas O.; Zhang, Qibin; Page, Jason S.; Shen, Yufeng; Callister, Stephen J.; Jacobs, Jon M.; Smith, Richard D.

    2008-01-01

    SUMMARY The future utility of liquid chromatography-mass spectrometry (LC-MS) in metabolic profiling and metabolomic studies for biomarker discover will be discussed, beginning with a brief description of the evolution of metabolomics and the utilization of the three most popular analytical platforms in such studies: NMR, GC-MS, and LC-MS. Emphasis is placed on recent developments in high-efficiency LC separations, sensitive electrospray ionization approaches, and the benefits to incorporating both in LC-MS-based approaches. The advantages and disadvantages of various quantitative approaches are reviewed, followed by the current LC-MS-based tools available for candidate biomarker characterization and identification. Finally, a brief prediction on the future path of LC-MS-based methods in metabolic profiling and metabolomic studies is given. PMID:19177179

  17. Measurement uncertainty for the determination of amphetamines in urine by liquid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Franco de Oliveira, Sarah Carobini Werner de Souza Eller; Yonamine, Mauricio

    2016-08-01

    A gas chromatography-mass spectrometry method for the determination of amphetamines in urine samples by means of liquid-phase microextraction was validated, including calculation of measurement uncertainty. After extraction in the three-phase mode, acceptor phase was withdrawn from the fiber and the residue was derivatized with trifluoroacetic anhydride. The method showed to be very simple, rapid and it required a significantly low amount of organic solvent for extraction. The limits of detection were 10 and 20μg/L for amphetamine and methamphetamine, respectively. The calibration curves were linear over the specified range (20μg/L to 1400μg/L; r(2)>0.99). The method showed to be both precise and accurate and a relative combined uncertainty of 2% was calculated. In order of importance, the factors which were more determinant for the calculation of method uncertainty were: analyte concentration, sample volume, trueness and method precision.

  18. Multiresidue determination of pesticides in agricultural products by gas chromatography/mass spectrometry with large volume injection.

    PubMed

    Saito, Yukio; Kodama, Shuji; Matsunaga, Akinobu; Yamamoto, Atsushi

    2004-01-01

    A method is described for the rapid determination of pesticide residues in agricultural products. Pesticides were extracted from samples with acetonitrile. To remove pigments and fatty acids, an aliquot of the extract was cleaned up by a minicolumn that was packed both with graphitized carbon black and primary secondary amine. Analysis was performed by gas chromatography/ mass spectrometry with programmable temperature vaporizer-based large volume injection using a liner packed with phenylmethylsilicone chemically bonded silica. The method was evaluated for 114 pesticides by spiking into tomato, spinach, Japanese pear, grape, and brown rice at various concentrations of each pesticide (0.02-0.4 microg/g). The method, which gave good recovery (>60%) for 108 pesticides, is characterized by high cleanup efficiency and short cleanup time, and is useful as a rapid screening analysis.

  19. Pharmacokinetic Studies of Chinese Medicinal Herbs Using an Automated Blood Sampling System and Liquid Chromatography-mass Spectrometry

    PubMed Central

    Wu, Yu-Tse; Wu, Ming-Tsang; Lin, Chia-Chun; Chien, Chao-Feng; Tsai, Tung-Hu

    2012-01-01

    The safety of herbal products is one of the major concerns for the modernization of traditional Chinese medicine, and pharmacokinetic data of medicinal herbs guide us to design the rational use of the herbal formula. This article reviews the advantages of the automated blood sampling (ABS) systems for pharmacokinetic studies. In addition, three commonly used sample preparative methods, protein precipitation, liquid-liquid extraction and solid-phase extraction, are introduced. Furthermore, the definition, causes and evaluation of matrix effects in liquid chromatography-mass spectrometry (LC/MS) analysis are demonstrated. Finally, we present our previous works as practical examples of the application of ABS systems and LC/MS for the pharmacokinetic studies of Chinese medicinal herbs. PMID:24716112

  20. Analysis of Indole Alkaloids from Rhazya stricta Hairy Roots by Ultra-Performance Liquid Chromatography-Mass Spectrometry.

    PubMed

    Akhgari, Amir; Laakso, Into; Seppänen-Laakso, Tuulikki; Yrjönen, Teijo; Vuorela, Heikki; Oksman-Caldentey, Kirsi-Marja; Rischer, Heiko

    2015-12-17

    Rhazya stricta Decne. (Apocynaceae) contains a large number of terpenoid indole alkaloids (TIAs). This study focused on the composition of alkaloids obtained from transformed hairy root cultures of R. stricta employing ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). In the UPLC-MS analyses, a total of 20 TIAs were identified from crude extracts. Eburenine and vincanine were the main alkaloids followed by polar glucoalkaloids, strictosidine lactam and strictosidine. Secodine-type alkaloids, tetrahydrosecodinol, tetrahydro- and dihydrosecodine were detected too. The occurrence of tetrahydrosecodinol was confirmed for the first time for R. stricta. Furthermore, two isomers of yohimbine, serpentine and vallesiachotamine were identified. The study shows that a characteristic pattern of biosynthetically related TIAs can be monitored in Rhazya hairy root crude extract by this chromatographic method.

  1. Pyrolysis-capillary gas chromatography-mass spectrometry for the determination of polyvinyl chloride traces in solid environmental samples.

    PubMed

    Tienpont, B; David, F; Vanwalleghem, F; Sandra, P

    2001-03-16

    A novel method based on pyrolysis-capillary gas chromatography-mass spectrometry (CGC-MS) was developed for the quantitative analysis of polyvinylchloride (PVC) in solid environmental samples like sludge and dust. The samples are extracted and the extract is fractionated by solid-phase extraction (SPE). Possibly interfering biological and frequently occuring synthetic polymers are removed by this clean-up. The final extract is analyzed by pyrolysis-CGC-MS. Selective detection of PVC is performed by using specific markers in the pyrogram. Quantitation is done on naphthalene. Good linearity was obtained in a range from 0.5 to 100 microg applied to the pyrolyser. The limit of quantitation (LOQ) in sludge and dust samples is 10 mg/kg dry mass. A correlation between PVC and phthalates was made for sewage sludge samples.

  2. Characterisation of odorants in roasted stem tea using gas chromatography-mass spectrometry and gas chromatography-olfactometry analysis.

    PubMed

    Sasaki, Tetsuya; Koshi, Erina; Take, Harumi; Michihata, Toshihide; Maruya, Masachika; Enomoto, Toshiki

    2017-04-01

    Roasted stem tea has a characteristic flavour, which is obtained by roasting tea stems, by-product of green tea production. This research aims to understand the characteristic odorants in roasted stem tea by comparing it to roasted leaf tea. We revealed potent odorants in commercial roasted stem tea using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry with aroma extract dilution analysis (AEDA). The difference between roasted stem and leaf tea derived from the same tea plants were investigated using GC-MS. Pyrazine compounds exhibited a roasted odour and high flavour dilution (FD) factors, as determined via AEDA. Roasted stem tea was richer in these pyrazines than roasted leaf tea. Geraniol and linalool exhibited high FD factors and a floral odour, and roasted stem tea was richer in these compounds than roasted leaf tea. These results may have a positive impact on the development of tea products.

  3. Improved peak selection strategy for automatically determining minute compositional changes in fuels by gas chromatography-mass spectrometry.

    PubMed

    Cramer, Jeffrey A; Begue, Nathan J; Morris, Robert E

    2011-02-11

    During the development of automated computational methods to detect minute compositional changes in fuels, it became apparent that peak selection through the spectral deconvolution of gas chromatography-mass spectrometry (GC-MS) data is limited by the complexity and noise levels inherent in the data. Specifically, current techniques are not capable of detecting minute, chemically relevant compositional differences with sufficient sensitivity. Therefore, an alternative peak selection strategy was developed based on spectral interpretation through interval-oriented parallel factor analysis (PARAFAC). It will be shown that this strategy outperforms the deconvolution-based peak selection strategy as well as two control strategies. Successful application of the PARAFAC-based method to detect minute chemical changes produced during microbiological growth in four different inoculated diesel fuels will be discussed.

  4. Analyzing salvia divinorum and its active ingredient salvinorin a utilizing thin layer chromatography and gas chromatography/mass spectrometry.

    PubMed

    Jermain, John D; Evans, Hiram K

    2009-05-01

    In recent years, Salvia divinorum has become a major focus by state legislatures throughout the United States looking to prohibit the sale of the psychoactive plant. After researching testing procedures presented in the literature and those employed by crime laboratories throughout the country, it was decided that thin layer chromatography (TLC) and gas chromatography/mass spectrometry (GC/MS) were the methods to use to analyze plant material for salvinorin A. With TLC, salvinorin A was detected from extracted plant material and was easily distinguishable from 13 other Salvia species as well as Cannabis sativa L. (marijuana). When using GC/MS, salvinorin A was best extracted from plant material with chloroform at ambient temperature when using a nonpolar solvent and acetone at ambient temperature when using a polar solvent. By utilizing these techniques, criminalists are now able to confirm the presence of salvinorin A in a submitted plant material suspected to be Salvia divinorum.

  5. Characterization by gas chromatography-mass spectrometry of diterpenoid resinous materials in Roman-age amphorae from northern Greece.

    PubMed

    Dimitrakoudi, Evagelia A; Mitkidou, Sofia A; Urem-Kotsou, Dushka; Kotsakis, Kostas; Stephanidou-Stephanatou, Julia; Stratis, John A

    2011-01-01

    A combined gas chromatography-mass spectrometry approach has been used for the characterization of two lumps of resin and 17 adsorbed residues on Roman-age vessels, mainly amphorae, from northern Greece. The data show that a diterpenic resin from plants of the Pinacae family is the main component of the tarry material associated with the analyzed archaeological samples. The identification and mass spectrometric fragmentation of several characteristic diterpenoid biomarkers is discussed. The abundance of secondary products identified in the archaeological samples suggests that the oxidative degradation of abietic acid and dehydroabietic acid to aromatic products was the main pathway. Of particular interest is the presence of characteristic saturated abietane hydrocarbons in one sample, which indicate that a reductive process also occurred on a small scale. The overall similarity in the composition of the residues suggests the common use of pine tar as a waterproofing and sealing agent at different sites in northern Greece during the Roman period.

  6. Fatty acid composition of wild mushroom species of order Agaricales--examination by gas chromatography-mass spectrometry and chemometrics.

    PubMed

    Marekov, Ilko; Momchilova, Svetlana; Grung, Bjørn; Nikolova-Damyanova, Boryana

    2012-12-01

    Applying gas chromatography-mass spectrometry of 4,4-dimethyloxazoline fatty acid derivatives, the fatty acid composition of 15 mushroom species belonging to 9 genera and 5 families of order Agaricales growing in Bulgaria is determined. The structure of 31 fatty acids (not all present in each species) is unambiguously elucidated, with linoleic, oleic and palmitic acids being the main components (ranging between 70.9% (Marasmius oreades) and 91.2% (Endoptychum agaricoides)). A group of three hexadecenoic positionally isomeric fatty acids, 6-, 9- and 11-16:1, appeared to be characteristic components of the examined species. By applying chemometrics it was possible to show that the fatty acid composition closely reflects the classification of the species. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Analysis of polyphenolic antioxidants from the fruits of three pouteria species by selected ion monitoring liquid chromatography-mass spectrometry.

    PubMed

    Ma, Jun; Yang, Hui; Basile, Margaret J; Kennelly, Edward J

    2004-09-22

    Pouteria campechiana, Pouteria sapota, and Pouteria viridis are tropical plants in the Sapotaceae family that bear edible fruits. The fresh fruits of these three Pouteria species were each extracted, and activity-guided fractionations were performed to identify the antioxidant constituents. Seven polyphenolic antioxidants, gallic acid (1), (+)-gallocatechin (2), (+)-catechin (3), (-)-epicatechin (4), dihydromyricetin (5), (+)-catechin-3-O-gallate (6), and myricitrin (7), were isolated and identified. Extracts of the three Pouteria fruits were analyzed by a selected ion monitoring liquid chromatography-mass spectrometry method to quantify their polyphenolic antioxidants. The highest level of the seven measured polyphenols was found in P. sapota, the second highest in P. viridis, and the lowest in P. campechiana. The levels of the seven polyphenols corresponded with the results of the 1,1-diphenyl-2-picrylhydrazyl assay, by which P. sapota had the highest antioxidant activity, P. viridis the second highest, and P. campechiana the lowest.

  8. Determination of testosterone:epitestosterone ratio after pentafluorophenyldimethylsilyl-trimethylsilyl derivatisation using gas chromatography-mass spectrometry in equine urine.

    PubMed

    Choi, M H; Kim, J Y; Chung, B C

    1999-05-01

    A highly specific method is described for measuring the testosterone:epitestosterone ratio in equine urine by gas chromatography-mass spectrometry (GC-MS) with stable isotope internal standards. The procedure was based on Serdolit Pad-1 resin extraction, enzymatic hydrolysis, and chemical derivatisation prior to instrumental analysis. The mixed derivatives, 3-trimethylsilyl-17-pentafluorophenyldimethylsilyl ether (3-TMS-17-flophemesyl) testosterone and epitestosterone, were found to have excellent analytical properties. The specificity of the derivatisation method exploits a unique feature of steroids: the selective exchange of the alcoholic flophemesyl ether for the trimethylsilyl ether. The sensitivity and specificity of the mixed 3-TMS-17-flophemesyl derivatives allow adequate determinations of testosterone and epitestosterone, even in urine from mares, in 5 ml samples. The repeatability of testosterone and epitestosterone was 6.2 and 5.7%, respectively, and their reproducibility was in the range of 6.4-8.7%.

  9. Protocol: A simple protocol for quantitative analysis of bio-oils through gas- chromatography/mass spectrometry.

    PubMed

    Bartoli, Mattia; Rosi, Luca; Frediani, Marco; Frediani, Piero

    2016-01-01

    A new and simple protocol for quantitative analysis of bio-oils using gas-chromatography/mass spectrometry is suggested. Compounds were identified via their mass spectra, and then unavailable response factors were calculated with respect to diphenyl as the internal standard using a modified method previously suggested for gas chromatography with flame ionization detection. This new protocol was applied to the characterization of bio-oils obtained from the pyrolysis of woods of different sources or using different pyrolysis procedures. This protocol allowed evaluation of the yields of products from poplar pyrolysis (among 50% and 99%), while a reduced amounts of products were identified from the pyrolysis of cellulose (between 46% and 58%). The main product was always acetic acid, but it was formed in very large yields from poplar while lower yields were obtained from cellulose.

  10. Simultaneous determination of alachlor, metolachlor, atrazine, and simazine in water and soil by isotope dilution gas chromatography/mass spectrometry

    SciTech Connect

    Huang, L.Q.

    1989-03-01

    A multiresidue method was developed for the simultaneous determination of low parts per billion (ppb) concentrations of the herbicides alachlor, metolachlor, atrazine, and simazine in water and soil using isotope dilution gas chromatography/mass spectrometry (GC/MS). Known amounts of /sup 15/N,/sup 13/C-alachlor and /sup 2/H/sub 5/-atrazine were added to each sample as internal standards. The samples were then prepared by a solid phase extraction with no further cleanup. A high resolution GC/low resolution MS system with data acquisition in selected ion monitoring mode was used to quantitate herbicides in the extract. The limit of detection was 0.05 ppb for water and 0.5 ppb for soil. Accuracy greater than 80% and precision better than 4% was demonstrated with spiked samples.

  11. Ultra trace determination of fluorobenzoic acids in reservoir and ground water using isotope dilution gas chromatography mass spectrometry.

    PubMed

    Müller, Karsten; Seubert, Andreas

    2014-06-01

    The accurate ultra-trace analysis of six fluorobenzoic acids (FBAs) via isotope dilution gas chromatography mass spectrometry through their deuterated analogues is described. North Sea reservoir and ground water samples were spiked with six deuterated FBAs (dFBAs), enriched using solid-phase extraction (SPE) and analysed using GC/MS after derivatisation with BF 3· MeOH. All FBAs were enriched and determined simultaneously. SPE allowed a 250-fold enrichment of the acids if 100 mL of sample volume was used. The method enables the determination of FBAs down to the range of 8-37 ng L (-1) with recoveries between 66 % and 85 %. It uses low amounts of chemicals and is adaptable to larger and smaller sample volumes.

  12. Gas Chromatography-Mass Spectrometry Analysis of Constituent Oil from Lingzhi or Reishi Medicinal Mushroom, Ganoderma lucidum (Agaricomycetes), from Nigeria.

    PubMed

    Ohiri, Reginald Chibueze; Bassey, Essien Eka

    2016-01-01

    Gas chromatography-mass spectrometry analysis of constituent oil from dried Ganoderma lucidum was carried out. Fresh G. lucidum obtained from its natural environment was thoroughly washed with distilled water and air-dried for 2 weeks and the component oils were extracted and analyzed. Four predominant components identified were pentadecanoic acid, 14-methyl-ester (retention time [RT] = 19.752 minutes; percentage total = 25.489), 9,12-octadecadienoic acid (Z,Z)- (RT = 21.629 minutes and 21.663 minutes; percentage total = 25.054), n-hexadecanoic acid (RT = 20.153 minutes; percentage total = 24.275), and 9-octadecenoic acid (Z)-, methyl ester (RT = 21.297 minutes; percentage total = 13.027). The two minor oils identified were 9,12-octadecadienoic acid, methyl ester, (E,E)- and octadecanoic acid, methyl ester (RT = 21.246 minutes and 21.503 minutes; percentage total = 7.057 and 5.097, respectively).

  13. Determination of benzene in soft drinks and other beverages by isotope dilution headspace gas chromatography/mass spectrometry.

    PubMed

    Cao, Xu-Liang; Casey, Valerie; Seaman, Steve; Tague, Brett; Becalski, Adam

    2007-01-01

    An automated, simple, and reproducible method was developed for the determination of benzene in soft drinks, based on isotope dilution headspace gas chromatography/mass spectrometry in the selected-ion monitoring mode. The method was used to assess benzene levels in samples of 124 soft drinks and beverages. Benzene was not detected in 60% of the 124 products. The average benzene levels in 6 products exceeded the Canadian maximum acceptable concentration of 5 microg/L for benzene in drinking water, and 2 of the 6 products had benzene levels above the World Health Organization guideline of 10 microg/L. The highest level of benzene, 23 microg/L, was found in a soft drink product specifically marketed to children.

  14. Headspace solid-phase microextraction for characterization of fragrances of lemon verbena (Aloysia triphylla) by gas chromatography-mass spectrometry.

    PubMed

    Kim, Nam-Sun; Lee, Dong-Sun

    2004-01-01

    Natural fragrances from lemon verbena (Aloysia triphylla) were studied by headspace solid phase microextraction (HS-SPME) techniques followed by gas chromatography-mass spectrometry (GC-MS), with six different fibre coatings being tested to evaluate the extraction efficiencies of several selected compounds. A total of 14 compounds were identified in the fragrances of lemon verbena. Geranial and neral were detected as major components and alpha-pinene, beta-pinene, beta-caryophyllene, and curcumene as minor components. Enantiomeric analysis of chiral compounds from lemon verbena was carried out on a chiral column. alpha-Pinene, limonene, and camphor in the fragrances emitted from lemon verbena were found in the (+), (-), and (-) forms, respectively.

  15. Characterization of novel varietal floral hop aromas by headspace solid phase microextraction and gas chromatography-mass spectrometry/olfactometry.

    PubMed

    Van Opstaele, Filip; De Causmaecker, Brecht; Aerts, Guido; De Cooman, Luc

    2012-12-19

    In this study, headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) were optimized and implemented to investigate the volatile composition of novel floral hop essences prepared from four German aroma hop varieties. In total, 91 different constituents were assigned, which were further grouped into monoterpene hydrocarbons, esters, ketones, aldehydes, furans, and oxygenated and nonoxygenated sesquiterpenes. Most volatiles belong to the ester group, whereas the monoterpene hydrocarbon β-myrcene appears to be the predominant compound in all hop oil preparations investigated. Furthermore, as demonstrated by principal component analysis, varietal floral hop essences are clearly discriminated on the basis of their characteristic volatile composition. Via GC-olfactometry on the floral essence variety Spalter Select, β-myrcene and 2-undecanone were identified as the most potent odorants. Several hop oil constituents were reported for the first time as impact odorants of hop aroma.

  16. Ink dating using thermal desorption and gas chromatography/mass spectrometry: comparison of results obtained in two laboratories.

    PubMed

    Koenig, Agnès; Bügler, Jürgen; Kirsch, Dieter; Köhler, Fritz; Weyermann, Céline

    2015-01-01

    An ink dating method based on solvent analysis was recently developed using thermal desorption followed by gas chromatography/mass spectrometry (GC/MS) and is currently implemented in several forensic laboratories. The main aims of this work were to implement this method in a new laboratory to evaluate whether results were comparable at three levels: (i) validation criteria, (ii) aging curves, and (iii) results interpretation. While the results were indeed comparable in terms of validation, the method proved to be very sensitive to maintenances. Moreover, the aging curves were influenced by ink composition, as well as storage conditions (particularly when the samples were not stored in "normal" room conditions). Finally, as current interpretation models showed limitations, an alternative model based on slope calculation was proposed. However, in the future, a probabilistic approach may represent a better solution to deal with ink sample inhomogeneity. © 2014 American Academy of Forensic Science.

  17. Dissimilarity analysis and automatic identification of monomethylalkanes from gas chromatography mass spectrometry data 1. Principle and protocols.

    PubMed

    Zhang, Liangxiao; Liang, Yizeng

    2009-07-03

    Monomethylalkanes are common but important components in many naturally occurring and synthetic organic materials. Generally, this kind of compounds is routinely analyzed by gas chromatography mass spectrometry (GC-MS) and identified by the retention pattern or similarity matching to the reference mass spectral library. However, these identification approaches rely on the limited standard database or costly standard compounds. When unknown monomethylalkane is absent from the reference library, these approaches might be less useful. In this study, based on the fragmentation rules and empirical observation, many interesting mass spectral characteristics of monomethylalkanes were discovered and employed to infer the number of carbon atoms and methylated position. Combined with the retention pattern, a protocol was described for the identification of monomethylalkane analyzed by GC-MS. After tested by simulated data and GC-MS data of the gasoline sample, it was demonstrated that the developing approach could automatically and correctly identify monomethylalkanes in complicated GC-MS data.

  18. Determination of chlorpromazine and its major metabolites by gas chromatography/mass spectrometry: application to biological fluids.

    PubMed

    Gruenke, L D; Craig, J C; Klein, F D; Nguyen, T L; Hitzemann, B A; Holaday, J W; Loh, H H; Braff, L; Fischer, A; Glick, I D

    1985-12-01

    A method for the quantitative determination of chlorpromazine and five of its major metabolites in a single sample of biological fluid in the ng/ml range has been developed utilizing gas chromatography/mass spectrometry with selected ion recording. The assay is highly specific and quantification is accomplished by an inverse stable isotope dilution technique, using deuterium-labeled variants of the compounds as internal standards. In this way the concentrations of chlorpromazine and five of its major metabolites (the sulfoxide, the N-oxide, the monodemethylated, the didemethylated, and the 7-hydroxylated compounds) can be determined in biological fluids. Levels in humans have been measured both in plasma and in red blood cells and are compared to those found in related in vitro studies.

  19. Dual low thermal mass gas chromatography-mass spectrometry for fast dual-column separation of pesticides in complex sample.

    PubMed

    Sasamoto, Kikuo; Ochiai, Nobuo; Kanda, Hirooki

    2007-07-31

    A method is described for fast dual-column separation of pesticides by use of dual low thermal mass gas chromatography-mass spectrometry (dual LTM-GC-MS) with different temperature programming. The method can provide two total ion chromatograms with different separation on DB-5 and DB-17 in a single run, which allows improved identification capability, even with short analysis time (<17 min). Also simultaneous detection with MS and elemental selective detector, e.g. pulsed flame photometric detection (PFPD) was evaluated for fast dual-column separation of 82 pesticide mixtures including 27 phosphorus pesticides. Dual LTM-GC-MS/PFPD was applied to analysis of pesticides in a brewed green tea sample with dual stir bar sorptive extraction method (dual SBSE).

  20. Volatile constituents of Murraya koenigii fresh leaves using headspace solid phase microextraction--gas chromatography-mass spectrometry.

    PubMed

    Sukkaew, Sayamol; Pripdeevech, Patcharee; Thongpoon, Chalermporn; Machan, Theeraphan; Wongchuphan, Rattana

    2014-12-01

    The volatile components of Murraya koenigii fresh leaves, collected from Surat Thani province, Thailand were studied by using headspace (HS) solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS). The four fibers employed to extract the volatiles were polydimethylsiloxane (PDMS), polydimethylsiloxane-divinylbenzene (PDMS-DVB), carboxane-polydimethylsiloxane (CAR-PDMS) and polydimethylsiloxane-divinylbenzene-carboxane (PDMS-DVB-CAR). The volatile constituents of M. koenigii fresh leaves were also extracted by hydrodistillation and analyzed by GC-MS. Fifty-one compounds were identified by these fibers. Five major compounds, γ-terpinene, β-caryophyllene, β-phellandrene, a-selinene and a-pinene, were detected in all fibers. The PDMS-DVB-CAR fiber was considered as the best for trapping key volatiles of M. koenigii fresh leaves.

  1. A liquid chromatography/mass spectrometry-based generic detection method for biochemical assay and hit discovery of histone methyltransferases.

    PubMed

    Li, Shu; Gu, X Justin; Hao, Qin; Fan, Hong; Li, Ling; Zhou, Shaolian; Zhao, Kehao; Chan, Ho Man; Wang, Y Karen

    2013-12-15

    Epigenetic modifications of the genome, such as DNA methylation and posttranslational modifications of histone proteins, contribute to gene regulation. Growing evidence suggests that histone methyltransferases are associated with the development of various human diseases, including cancer, and are promising drug targets. High-quality generic assays will facilitate drug discovery efforts in this area. In this article, we present a liquid chromatography/mass spectrometry (LC/MS)-based S-adenosyl homocysteine (SAH) detection assay for histone methyltransferases (HMTs) and its applications in HMT drug discovery, including analyzing the activity of newly produced enzymes, developing and optimizing assays, performing focused compound library screens and orthogonal assays for hit confirmations, selectivity profiling against a panel of HMTs, and studying mode of action of select hits. This LC/MS-based generic assay has become a critical platform for our methyltransferase drug discovery efforts.

  2. Determination of O-ethyl S-2-diisopropylaminoethyl methylphosphonothioate (VX) by thermospray liquid chromatography-mass spectrometry.

    PubMed

    Wils, E R; Hulst, A G

    1990-12-07

    The determination of the nerve agent O-ethyl S-2-diisopropylaminoethyl methylphosphonothioate (VX) by thermospray liquid chromatography-mass spectrometry was studied. The solvent system acetonitrile-methanol-0.25 M ammonium acetate was used on a reversed-phase C18 column. By selected ion monitoring at the protonated molecular ion of VX (m/z 268), the predominant peak in its thermospray mass spectrum, an amount of 200 pg could be detected. For the determination of VX in water at levels below 1 ng/ml, preconcentration by C18 cartridges was investigated. The applicability of the method was demonstrated by the determination of VX in spiked river waters. A concentration of 0.1 ng/ml could be detected starting from a water sample of 50 ml. A second application concerned the analysis of water extracts of spiked soil samples.

  3. Analysis of volatile components in a Chinese fish sauce, Fuzhou Yulu, by gas chromatography-mass spectrometry*

    PubMed Central

    Yang, Yuan-fan; Chen, Shen-ru; Ni, Hui; Ye, Xing-qian

    2008-01-01

    Volatile components of Fuzhou Yulu, a Chinese fish sauce, were analyzed by gas chromatography-mass spectrometry (GC-MS), and two pretreatment methods, i.e., purge and trap (P&T) GC-MS and ethyl acetate extraction followed by GC-MS, were compared. P&T-GC-MS method determined 12 components, including sulfur-containing constituents (such as dimethyl disulfide), nitrogen-containing constituents (such as pyrazine derivatives), aldehydes and ketones. Ethyl acetate extraction followed by GC-MS method detected 10 components, which were mainly volatile organic acids (such as benzenepropanoic acid) and esters. Neither of the two methods detected alcohols or trimethylamine. This study offers an important reference to determine volatile flavor components of traditional fish sauce through modern analysis methods. PMID:19067466

  4. Analysis of volatile components in a Chinese fish sauce, Fuzhou Yulu, by gas chromatography-mass spectrometry.

    PubMed

    Yang, Yuan-fan; Chen, Shen-ru; Ni, Hui; Ye, Xing-qian

    2008-12-01

    Volatile components of Fuzhou Yulu, a Chinese fish sauce, were analyzed by gas chromatography-mass spectrometry (GC-MS), and two pretreatment methods, i.e., purge and trap (P&T) GC-MS and ethyl acetate extraction followed by GC-MS, were compared. P&T-GC-MS method determined 12 components, including sulfur-containing constituents (such as dimethyl disulfide), nitrogen-containing constituents (such as pyrazine derivatives), aldehydes and ketones. Ethyl acetate extraction followed by GC-MS method detected 10 components, which were mainly volatile organic acids (such as benzenepropanoic acid) and esters. Neither of the two methods detected alcohols or trimethylamine. This study offers an important reference to determine volatile flavor components of traditional fish sauce through modern analysis methods.

  5. Use of gas chromatography-mass spectrometry/solid phase microextraction for the identification of MVOCs from moldy building materials.

    PubMed

    Wady, Loay; Bunte, Annicka; Pehrson, Christina; Larsson, Lennart

    2003-03-01

    Gas chromatography-mass spectrometry/solid phase microextraction (GC-MS/SPME) was applied to identify microbial volatile organic compounds (MVOCs) in water-damaged, mold-infested building materials (gypsum board papers (n=2), mineral wool, and masonite) and in cultivated molds (Aspergillus penicillioides, Stachybotrys chartarum, and Chaetomium globosum). Three SPME fibers (65-microm PDMS-DVB, 75-microm Carboxen-PDMS, and 70-microm Carbowax-stableflex) designed for automated injection were used of which the latter showed best performance. A number of previously reported MVOCs were detected both in the building materials and the cultivated molds. In addition, methyl benzoate was identified both in the S. chartarum and A. penicillioides cultures and in the building materials. SPME combined with GC-MS may be a useful method for the determination of MVOCs emitted from mold-infested building materials.

  6. Environmental and biological determination of acrolein using new cold fiber solid phase microextraction with gas chromatography mass spectrometry.

    PubMed

    Dias, Cláudia M; Menezes, Helvécio C; Cardeal, Zenilda L

    2017-04-01

    Acrolein is a pollutant released daily to the indoor environment from different sources. The present study reports the development of a simple and sensitive cold fiber solid phase microextraction sampling method for the determination of acrolein in exhaled air and indoor air by gas chromatography mass spectrometry. O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine was used as derivatizing agent supported on a 65-μm polydimethylsiloxane-divinylbenzene SPME fiber. An acrolein permeation tube at 326.25 ng min(-1) rate was used to generate gaseous standards. The method shows good results for main validation parameters. The limits of detection and quantification were 2.88 and 5.08 μg m(-3), respectively, for indoor analysis; and 2.40 and 3.79 μg m(-3), respectively, for exhaled air analysis. The precision showed standard deviation ranges from 6.00 to 8.00% for intra-assay analyses and from 8.00 to 10.00% for inter-assay analyses. After optimizing the conditions, analyses of real samples were performed on indoor environments contaminated by cigarette smoke, or heated oil, including pastry shops, restaurants, churros stands, and closed parking cars located in the city of Belo Horizonte, Brazil. Acrolein breaths of exposed people were also determined. A good Pearson correlation coefficient (r = 0.901) was observed between the concentration of acrolein in indoor air and exhaled air, allowing to propose acrolein breath as environmental exposure biomarker. Graphical Abstract Cold fiber solid phase microextraction gas chromatography/mass spectrometry.

  7. A gas chromatography-mass spectrometry-based metabolomic approach for the characterization of goat milk compared with cow milk.

    PubMed

    Scano, Paola; Murgia, Antonio; Pirisi, Filippo M; Caboni, Pierluigi

    2014-10-01

    In this work, the polar metabolite pool of commercial caprine milk was studied by gas chromatography-mass spectrometry and multivariate statistical data analysis. Experimental data were compared with those of cow milk and the discriminant analysis correctly classified milk. By the same means, differences due to heat treatments (UHT or pasteurization) on milk samples were also investigated. Results of the 2 discriminant analyses were combined, with the aim of finding the discriminant metabolites unique for each class and shared by 2 classes. Valine and glycine were specific to goat milk, talose and malic acid to cow milk, and hydroxyglutaric acid to pasteurized samples. Glucose and fructose were shared by cow milk and UHT-treated samples, whereas ribose was shared by pasteurized and goat milk. Other discriminant variables were not attributed to specific metabolites. Furthermore, with the aim to reduce food fraud, the issue of adulteration of caprine milk by addition of cheaper bovine milk has been also addressed. To this goal, mixtures of goat and cow milk were prepared by adding the latter in a range from 0 to 100% (vol/vol) and studied by multivariate regression analysis. The error in the level of cow milk detectable was approximately 5%. These overall results demonstrated that, through the combined approach of gas chromatography-mass spectrometry and multivariate statistical data analysis, we were able to discriminate between milk typologies on the basis of their polar metabolite profiles and to propose a new analytical method to easily discover food fraud and to protect goat milk uniqueness. The use of appropriate visualization tools improved the interpretation of multivariate model results. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  8. Identification of wild collected mosquito vectors of diseases using gas chromatography-mass spectrometry in Jazan Province, Saudi Arabia.

    PubMed

    Al Ahmed, Azzam M; Badjah-Hadj-Ahmed, Ahmed-Yacine; Al Othman, Zeid A; Sallam, Mohamed F

    2013-11-01

    Thirty-three species of mosquitoes have been reported from the Kingdom of Saudi Arabia. Several of these mosquitoes, Anopheles gambiae Giles s.l., Anopheles stephensi Liston, Culex pipiens Linnaeus, Culex quinquefasciatus Say, Culex tritaeniorhynchus Giles, Stegomyia aegypti (Linnaeus) and Aedimorphus vexans arabiensis (Patton) are known vectors of human and animal diseases. In this study, the cuticular hydrocarbon profiles of eight mosquito species using gas chromatography-mass spectrometry were analyzed. Wild collected fourth-instar larvae were reared, and single, newly emerged, unfed adult females were used for the analysis. A total of 146-160 peaks were detected from the cuticular extracts by gas chromatography. Repeated analysis of variance (ANOVA) and Tukey HSD Post Hoc test was used to test for quantitative differences in relative hydrocarbon quantity. In addition, a linear regression model was applied using Enter method to determine the diagnostic peaks for the eight mosquito specimens. The ANOVA test indicated that relative peaks were significant (P < 0.05) when selected pairs of peaks were compared. Also, seven compounds showed qualitative differences among the five mosquito vectors tested. The classes of constituents present were n-alkanes, monomethylalkanes, dimethylalkanes, trimethylalkanes, alkenes, branched aromatic hydrocarbons, aldehydes and esters. These compounds have a carbon chain length ranging from 8 to 18 carbons. The most abundant compound in all adult mosquito specimens was n-hexylacrylate [retention time (RT) 6.73 min], which was not detected in Cx. pipiens. In Cx. pipiens, the most abundant peak was benzaldehyde (RT 2.98 min). Gas chromatography-mass spectrometry is a suitable method to identify adult mosquitoes, especially from focal areas of public health concern such as Jazan Province, Saudi Arabia. This method allows a wide range of adult collected material to be identified with high accuracy.

  9. Polychlorinated diphenyl sulfides. Preparation of model compounds, chromatography, mass spectrometry, NMR, and environmental analysis

    SciTech Connect

    Sinkkonen, S.; Kolehmainen, E.; Laihia, K.; Koistinen, J.; Rantio, T.

    1993-07-01

    Some polychlorinated diphenyl sulfides were prepared by chlorination of diphenyl sulfide with sulfuryl chloride and by Friedel-Crafts-type reaction from 1,2-dichlorobenzene and sulfur. Individual isomers from the reaction mixtures were isolated by reversed-phase high-performance liquid chromatography. Mass spectra show the degree of chlorination of different compounds, and {sup 1}H and {sup 13}C NMR spectra verify their structures. Three trichloro isomers were shown to be 2,2{prime}, 4-, 2,4,4{prime}, and 2,4{prime},6-trichlorodiphenyl sulfides and two symmetric tetrachloro isomers bis(2,4-dichlorophenyl) and bis(3,4-dichlorophenyl) sulfides. Chlorine-induced {sup 13}C NMR substituent chemical shifts (SCS) have been calculated and compared with the experimental ones in the case of bis(2,4-dichlorophenyl) sulfide. Four stack gases from a waste incinerator and six pulp mill effluents from two bleaching plants were screened for the polychlorinated diphenyl sulfides. Trichlorodiphenyl sulfides were found from five pulp mill effluent samples and tri- and tetrachlorodiphenyl sulfides from two stack gas samples. 24 refs., 8 figs., 5 tabs.

  10. Methods of Analysis by the U.S. Geological Survey Organic Geochemistry Research Group - Determination of Glyphosate, Aminomethylphosphonic Acid, and Glufosinate in Water Using Online Solid-Phase Extraction and High-Performance Liquid Chromatography/Mass Spectrometry

    DTIC Science & Technology

    2002-01-01

    Glyphosate, Aminomethylphosphonic Acid, and Glufosinate in Water Using Online Solid-Phase Extraction and High-Performance Liquid Chromatography /Mass...Aminomethylphosphonic Acid, and Glufosinate in Water Using Online Solid-Phase Extraction and High-Performance Liquid Chromatography /Mass Spectrometry... Glufosinate in Water Using Online Solid-Phase Extraction and High-Performance Liquid Chromatography /Mass Spectrometry By E.A. Lee, A.P. Strahan, and

  11. [Determination of pesticide residues and microcystin in drinking water using on-line SPE liquid chromatography-mass spectrometry].

    PubMed

    Guo, Juan; Zhao, Yan; Zhang, Jing; Chen, Hongbing; Shao, Bing

    2012-03-01

    To develop a method based on on-line solid phase extraction followed liquid chromatography mass spectrometry for determination of 9 pesticides and microcystin-LR in drinking water. Drinking water samples were concentrated by a HRP-SPE cartridge and separated on a HSS T3 column with a gradient mobile phase of acetonitrile and aqueous 0.1% formic acid, then analyzed by triple quadrupole mass spectrometry (TQ-MS) and time of flight mass spectrometry (TOF-MS), respectively. Mass acquisition was conducted under positive electrospray ionization mode. Quantification was performed by external standard calibration. The quantification limits (LOQs) of 10 target compounds were far below the limits set by the National Standards for Drinking Water Quality. The LOQs of TOF-MS was 0.01-0.40 microg/L and the LOQs of TQ-MS was 0.01-0.19 microg/L. Recoveries of 10 target compounds were 66.5%-130.3% with relative standard deviation between 0.8% and 14.5%. Due to its rapidness, simpleness, and high sensitivity, the method is suitable for the determination of pesticides and microcystin-LR in drinking water.

  12. [Preparation of flavonoid reference standards from Scutellariae Radix under the guidance of high performance liquid chromatography-mass spectrometry analysis].

    PubMed

    Guo, Henan; Yang, Xuedong; Liu, Jun; Zheng, Wenfeng

    2012-07-01

    Flavonoid reference standards were targeted-prepared from Scutellariae Radix under the guidance of high performance liquid chromatography-mass spectrometry (HPLC-MS) analysis. With HPLC-MS analysis of Scutellariae Radix, 19 flavonoid components were identified by analyzing and comparing their retention times, ultraviolet spectra, and mass spectrometry data with literature. The separation and purification protocols of all targeted flavonoid reference standards were optimally designed according to the results of HPLC-MS analysis and related literature. The ethanol extract of Scutellariae Radix was suspended in water and extracted with petroleum ether, ethyl acetate, and n-butanol successively. The ethyl acetate extract and n-butanol extract were separately subjected to primary separation by low pressure reverse phase preparative chromatography. Then the fractions containing targeted compounds were further purified by low pressure reverse and normal phases preparative chromatography. Finally, baicalin and wogonoside reference standards were obtained from n-butanol extract; baicaelin, wogonin, and oroxylin A reference standards were obtained from ethyl acetate extract. The structures of the 5 reference standards were identified by mass spectrometry (MS) and 1H nuclear magnetic resonance (1H NMR) spectroscopy. The HPLC analytical results showed that the purities of the 5 reference standards were all above 98%. It is demonstrated that the rapid targeted-preparation method under the guidance of the HPLC-MS analysis is applicable for the isolation and preparation of chemical components in traditional Chinese medicines.

  13. Novel aspects of quantitation of immunogenic wheat gluten peptides by liquid chromatography-mass spectrometry/mass spectrometry.

    PubMed

    Sealey-Voyksner, Jennifer A; Khosla, Chaitan; Voyksner, Robert D; Jorgenson, James W

    2010-06-18

    A novel, specific and sensitive non-immunological liquid chromatography-mass spectrometry (LC-MS) based assay has been developed to detect and quantify trace levels of wheat gluten in food and consumer products. Detection and quantification of dietary gluten is important, because gluten is a principle trigger of a variety of immune diseases including food allergies and intolerances. One such disease, celiac sprue, can cause intestinal inflammation and enteropathy in patients who are exposed to dietary gluten. At present, immunochemistry is the leading analytical method for gluten detection in food. Consequently, enzyme-linked immunosorbent assays (ELISAs), such as the sandwich or competitive type assays, are the only commercially available methods to ensure that food and consumer products are accurately labeled as gluten-free. The availability of a comprehensive, fast and economic alternative to the immunological ELISA may also facilitate research towards the development of new drugs, therapies and food processing technologies to aid patients with gluten intolerances and for gluten-free labeling and certification purposes. LC-MS is an effective and efficient analytical technique for the study of cereal grain proteins and to quantify trace levels of targeted dietary gluten peptides in complex matrices. Initial efforts in this area afforded the unambiguous identification and structural characterization of six unique physiologically relevant wheat gluten peptides. This paper describes the development and optimization of an LC-MS/MS method that attempts to provide the best possible accuracy and sensitivity for the quantitative detection of trace levels of these six peptides in various food and consumer products. The overall performance of this method was evaluated using native cereal grains. Experimental results demonstrated that this method is capable of detecting and quantifying select target peptides in food over a range from 10pg/mg to 100ng/mg (corresponding to

  14. IDENTIFICATION OF POLAR DRINKING WATER DISINFECTION BY-PRODUCTS USING LIQUID CHROMATOGRAPHY - MASS SPECTROMETRY

    EPA Science Inventory

    A qualitative method using 2,4-dinitrophenylhydrazine (DNPH) derivatization followed by analysis with liquid chromatography (LC)/negative ion-electrospray mass spectrometry (MS) was developed for identifying polar aldehydes and ketones in ozonated drinking water. This method offe...

  15. IDENTIFICATION OF POLAR DRINKING WATER DISINFECTION BY-PRODUCTS USING LIQUID CHROMATOGRAPHY - MASS SPECTROMETRY

    EPA Science Inventory

    A qualitative method using 2,4-dinitrophenylhydrazine (DNPH) derivatization followed by analysis with liquid chromatography (LC)/negative ion-electrospray mass spectrometry (MS) was developed for identifying polar aldehydes and ketones in ozonated drinking water. This method offe...

  16. DETERMINATION OF A BOUND MUSK XYLENE METABOLITE IN CARP HEMOGLOBIN AS A BIOMARKER OF EXPOSURE BY GAS CHROMATOGRAPHY MASS SPECTROMETRY USING SELECTED ION MONITORING

    EPA Science Inventory

    Musk xylene (MX) is widely used as a fragrance ingredient in commercial toiletries. Identification and quantification of a bound 4-amino-MX (AMX) metabolite was carried out by gas chromatography-mass spectrometry (GC/MS), with selected ion monitoring (SIM). Detection of AMX occur...

  17. Analysis of swainsonine and swainsonine N-oxide as trimethylsilyl derivatives by Liquid Chromatography-Mass Spectrometry and their relative occurrence in plants toxic to livestock

    USDA-ARS?s Scientific Manuscript database

    A liquid chromatography-mass spectrometry method was developed for the analysis of the indolizidine alkaloid swainsonine and its N-oxide. The method is based on a one step solvent partitioning extraction procedure followed by trimethylsilylation of the dried extract and subsequent detection and qua...

  18. Quantitative Analysis of Bisphenol A Leached from Household Plastics by Solid-Phase Microextraction and Gas Chromatography-Mass Spectrometry (SPME-GC-MS)

    ERIC Educational Resources Information Center

    Johnson, Bettie Obi; Burke, Fernanda M.; Harrison, Rebecca; Burdette, Samantha

    2012-01-01

    The measurement of trace levels of bisphenol A (BPA) leached out of household plastics using solid-phase microextraction (SPME) with gas chromatography-mass spectrometry (GC-MS) is reported here. BPA is an endocrine-disrupting compound used in the industrial manufacture of polycarbonate plastic bottles and epoxy resin can liners. This experiment…

  19. METHOD 530 DETERMINATION OF SELECT SEMIVOLATILE ORGANIC CHEMICALS IN DRINKING WATER BY SOLID PHASE EXTRACTION AND GAS CHROMATOGRAPHY/ MASS SPECTROMETRY (GC/MS)

    EPA Science Inventory

    1.1. This is a gas chromatography/mass spectrometry (GC/MS) method for the determination of selected semivolatile organic compounds in drinking waters. Accuracy and precision data have been generated in reagent water, and in finished ground and surface waters for the compounds li...

  20. DETERMINATION OF A BOUND MUSK XYLENE METABOLITE IN CARP HEMOGLOBIN AS A BIOMARKER OF EXPOSURE BY GAS CHROMATOGRAPHY MASS SPECTROMETRY USING SELECTED ION MONITORING

    EPA Science Inventory

    Musk xylene (MX) is widely used as a fragrance ingredient in commercial toiletries. Identification and quantification of a bound 4-amino-MX (AMX) metabolite was carried out by gas chromatography-mass spectrometry (GC/MS), with selected ion monitoring (SIM). Detection of AMX occur...

  1. Lipid fatty acid profile analyses in liver and serum in rats with nonalcoholic steatohepatitis using improved gas chromatography-mass spectrometry methodology

    USDA-ARS?s Scientific Manuscript database

    Fatty acids (FA) are essential components of lipids and exhibit important biological functions. The analyses of FAs are routinely carried out by gas chromatography-mass spectrometry, after multi-step sample preparation. In this study, several key experimental factors were carefully examined, validat...

  2. Odor and odorous chemical emissions from dairy and swine facilities: Part 5-Simultaneous chemical and sensory analysis with Gas Chromatography - Mass Spectrometry - Olfactometry

    USDA-ARS?s Scientific Manuscript database

    Simultaneous chemical and sensory analyses using gas chromatography-mass spectrometry-olfactometry (GC-MS-O) for air samples collected at barn exhaust fans were used for quantification and ranking of odor impact of target odorous gases. Fifteen target odorous VOCs (odorants) were selected. Air sampl...

  3. Quantitative Analysis of Bisphenol A Leached from Household Plastics by Solid-Phase Microextraction and Gas Chromatography-Mass Spectrometry (SPME-GC-MS)

    ERIC Educational Resources Information Center

    Johnson, Bettie Obi; Burke, Fernanda M.; Harrison, Rebecca; Burdette, Samantha

    2012-01-01

    The measurement of trace levels of bisphenol A (BPA) leached out of household plastics using solid-phase microextraction (SPME) with gas chromatography-mass spectrometry (GC-MS) is reported here. BPA is an endocrine-disrupting compound used in the industrial manufacture of polycarbonate plastic bottles and epoxy resin can liners. This experiment…

  4. MEASUREMENT OF HIGH-MOLECULAR-WEIGHT POLYCYCLIC AROMATIC HYDROCARBONS IN SOILS BY PARTICLE BEAM HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY

    EPA Science Inventory

    Polycyclic aromatic hydrocarbons (PAHs) comprise a class of potentially hazardous compounds of concern to the U.S.EPA. The application of particle-beam (PB) liquid chromatography-mass spectrometry (LC-MS) to the measurement of high-molecular-weight PAHs was investigated. Instrume...

  5. Analysis of Whiskey by Dispersive Liquid-Liquid Microextraction Coupled with Gas Chromatography/Mass Spectrometry: An Upper Division Analytical Chemistry Experiment Guided by Green Chemistry

    ERIC Educational Resources Information Center

    Owens, Janel E.; Zimmerman, Laura B.; Gardner, Michael A.; Lowe, Luis E.

    2016-01-01

    Analysis of whiskey samples prepared by a green microextraction technique, dispersive liquid-liquid microextraction (DLLME), before analysis by a qualitative gas chromatography-mass spectrometry (GC/MS) method, is described as a laboratory experiment for an upper division instrumental methods of analysis laboratory course. Here, aroma compounds in…

  6. Analysis of Whiskey by Dispersive Liquid-Liquid Microextraction Coupled with Gas Chromatography/Mass Spectrometry: An Upper Division Analytical Chemistry Experiment Guided by Green Chemistry

    ERIC Educational Resources Information Center

    Owens, Janel E.; Zimmerman, Laura B.; Gardner, Michael A.; Lowe, Luis E.

    2016-01-01

    Analysis of whiskey samples prepared by a green microextraction technique, dispersive liquid-liquid microextraction (DLLME), before analysis by a qualitative gas chromatography-mass spectrometry (GC/MS) method, is described as a laboratory experiment for an upper division instrumental methods of analysis laboratory course. Here, aroma compounds in…

  7. METHOD 530 DETERMINATION OF SELECT SEMIVOLATILE ORGANIC CHEMICALS IN DRINKING WATER BY SOLID PHASE EXTRACTION AND GAS CHROMATOGRAPHY/ MASS SPECTROMETRY (GC/MS)

    EPA Science Inventory

    1.1. This is a gas chromatography/mass spectrometry (GC/MS) method for the determination of selected semivolatile organic compounds in drinking waters. Accuracy and precision data have been generated in reagent water, and in finished ground and surface waters for the compounds li...

  8. Liquid chromatography-mass spectrometry in in vitro drug metabolite screening.

    PubMed

    Tolonen, Ari; Turpeinen, Miia; Pelkonen, Olavi

    2009-02-01

    A combination of high performance liquid chromatography (HPLC) and mass spectrometry (LC/MS) has proven its status as the most powerful analytical tool for screening and identifying drug metabolites in modern drug discovery. These techniques have become irreplaceable for drug metabolism laboratories, providing high amounts of information from a wide variety of samples. This review focuses on the most common and useful applications of these techniques when working on in vitro metabolism, more specifically with screening and identification of chemically stable or reactive metabolites formed via biotransformation reactions. Matching specific tasks and suitable instruments is a recurring consideration; for many reasons, the time-of-flight or orbitrap mass spectrometry provides clearly increased efficiency in metabolite profiling compared to other types of mass spectrometry.

  9. Conformational changes of recombinant monoclonal antibodies by limited proteolytic digestion, stable isotope labeling, and liquid chromatography-mass spectrometry.

    PubMed

    Ponniah, Gomathinayagam; Nowak, Christine; Kita, Adriana; Cheng, Guilong; Kori, Yekaterina; Liu, Hongcheng

    2016-03-15

    Limited proteolytic digestion is a method with a long history that has been used to study protein domain structures and conformational changes. A method of combining limited proteolytic digestion, stable isotope labeling, and mass spectrometry was established in the current study to investigate protein conformational changes. Recombinant monoclonal antibodies with or without the conserved oligosaccharides, and with or without oxidation of the conserved methionine residues, were used to test the newly proposed method. All of the samples were digested in ammonium bicarbonate buffer prepared in normal water. The oxidized deglycosylated sample was also digested in ammonium bicarbonate buffer prepared in (18)O-labeled water. The sample from the digestion in (18)O-water was spiked into each sample digested in normal water. Each mixed sample was subsequently analyzed by liquid chromatography-mass spectrometry (LC-MS). The molecular weight differences between the peptides digested in normal water versus (18)O-water were used to differentiate peaks from the samples. The relative peak intensities of peptides with or without the C-terminal incorporation of (18)O atoms were used to determine susceptibility of different samples to trypsin and chymotrypsin. The results demonstrated that the method was capable of detecting local conformational changes of the recombinant monoclonal antibodies caused by deglycosylation and oxidation. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Batch-processing of imaging or liquid-chromatography mass spectrometry datasets and De Novo sequencing of polyketide siderophores.

    PubMed

    Novák, Jiří; Sokolová, Lucie; Lemr, Karel; Pluháček, Tomáš; Palyzová, Andrea; Havlíček, Vladimír

    2017-07-01

    The open-source and cross-platform software CycloBranch was utilized for dereplication of organic compounds from mass spectrometry imaging imzML datasets and its functions were illustrated on microbial siderophores. The pixel-to-pixel batch-processing was analogous to liquid chromatography mass spectrometry data. Each data point represented here by accurate m/z values and the corresponding ion intensities was matched against integrated compound libraries. The fine isotopic structure matching was also embedded into CycloBranch dereplication process. The siderophores' characterization from single-pixel mass spectra was further supported by their de novo sequencing. New ketide building block library was utilized by CycloBranch to characterize the siderophores in images and mixtures and nomenclature of fragment ion series of linear and cyclic polyketide siderophores was proposed. The software is freely available at http://ms.biomed.cas.cz/cyclobranch. This article is part of a Special Issue entitled: MALDI Imaging, edited by Dr. Corinna Henkel and Prof. Peter Hoffmann. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Effect of organic mobile phase composition on signal responses for selected polyalkene additive compounds by liquid chromatography-mass spectrometry.

    PubMed

    Duderstadt, Randall E; Fischer, Steven M

    2008-06-06

    The high performance liquid chromatography (HPLC) separation methodology employed in the study of polyalkene additive compounds by atmospheric pressure ionization mass spectrometry (API-MS) was undertaken. Both atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) were examined. APPI (including dopant-assisted APPI) was found to be an inferior ionization technique to APCI in all cases. APCI ion responses were found to be highly dependent upon the organic solvent type used in the HPLC separations. Namely, employing a water/methanol gradient in place of a water/acetonitrile or a water/acetone gradient yielded improvements in analyte ion intensities between 2.3- and 52-fold for the liquid chromatography-mass spectrometry (LC-MS) experiments. Analyte and mobile phase solvent ionization energies were found to be only partially responsible, whereas mobile phase cluster formation and hydration was also implicated. Mobile phase component modification is demonstrated to be an important consideration when developing new, or modifying existing HPLC separations for use in LC-MS experiments in order to enhance analyte sensitivity for a wide variety of common polyalkene additives.

  12. [Simultaneous determination of 16 organic acids in feed additives by on-line enrichment and ion chromatography-mass spectrometry].

    PubMed

    Xiong, Zhiyu; Dong, Ying; Zhou, Hongbin; Yu, Yang; Li, Jing; Sun, Li

    2014-02-01

    A novel analytical method for simultaneous determination of sixteen organic acids by on-line enrichment and ion chromatography-mass spectrometry (IC-MS) was developed. Online enrichment and separation of the organic acids were performed by ion chromatography on a homemade enrichment column and a homemade separation column. The qualitative and quantitative analyses of the organic acids were performed by mass spectrometry in selected ion monitoring (SIM) mode on the basis of atmospheric pressure chemical ionization (APCI) source in negative mode. The sample of 200 microL was injected for the analysis, and the on-line enrichment time was 3 min. The sodium hydroxide solution was used as a gradient elution system. The two columns made it possible to have a low limit of detection due to the good enrichment and separation capability. The sixteen organic acids were separated completely within 30 min. All curves showed good linearity within the test concentration ranges. The limits of detection (LODs) were between 0.01 and 0.22 mg/L, and the average recoveries were between 70.6% and 110.8%. The relative standard deviations (RSDs) were less than 6.3%. The results indicate that this method is simple, rapid, sensitive and accurate for the determination of the organic acids in feed additives.

  13. Determination of epichlorohydrin by sulfite derivatization and ion chromatography: characterization of the sulfite derivatives by ion chromatography-mass spectrometry.

    PubMed

    Bruzzoniti, Maria Concetta; Andrensek, Samo; Novic, Milko; Perrachon, Daniela; Sarzanini, Corrado

    2004-04-23

    This work is an upgrade of a previously developed method (J. Chromatogr. A 884 (2000) 251] for epichlorohydrin determination by ion chromatography (IC) and conductivity detection. Here, an ion chromatography-mass spectrometry (IC-MS) coupling has been employed for the separation and the identification of products of epichlorohydrin when reacted with the nucleophilic agent SO3(2-). The high capacity column (IonPac AS11-HC) used for separation provided good resolution. This allowed evaluation of the IC behavior and mass spectrometric identification of epichlorohydrin sulfite derivatives. By using atmospheric pressure interfaces (ESI and APCI) the following species were tentatively identified: 2,3-dihydroxy-1-propanesulfonic, 2,3-epoxy-1-propanesulfonic,1,3-dihydroxy-2-propanesulfonic and 3-oxetanesulfonic acids and 2-hydroxy-1,3-propanedisulfonic acid (or its isomer 3-hydroxy-1,2-propanedisulfonic acid). The study showed that chlorine atoms are displaced from epichlorohydrin during the reaction, while mass spectrometry confirmed that none of the products formed contains chlorine atoms.

  14. [Determination of acetanilide herbicide residues in tea by gas chromatography-mass spectrometry with two different ionization techniques].

    PubMed

    Shen, Weijian; Xu, Jinzhong; Yang, Wenquan; Shen, Chongyu; Zhao, Zengyun; Ding, Tao; Wu, Bin

    2007-09-01

    An analytical method of solid phase extraction-gas chromatography-mass spectrometry with two different ionization techniques was established for simultaneous determination of 12 acetanilide herbicide residues in tea-leaves. Herbicides were extracted from tea-leaf samples with ethyl acetate. The extract was cleaned-up on an active carbon SPE column connected to a Florisil SPE column. Analytical screening was determined by the technique of gas chromatography (GC)-mass spectrometry (MS) in the selected ion monitoring (SIM) mode with either electron impact ionization (EI) or negative chemical ionization (NCI). It is reliable and stable that the recoveries of all herbicides were in the range from 50% to 110% at three spiked levels, 10 microg/kg, 20 microg/kg and 40 microg/kg, and the relative standard deviations (RSDs) were no more than 10.9%. The two different ionization techniques are complementary as more ion fragmentation information can be obtained from the EI mode while more molecular ion information from the NCI mode. By comparison of the two techniques, the selectivity of NCI-SIM was much better than that of EI-SIM method. The sensitivities of the both techniques were high, the limit of quantitative (LOQ) for each herbicide was no more than 2.0 microg/kg, and the limit of detection (LOD) with NCI-SIM technique was much lower than that of EI-SIM when analyzing herbicides with several halogen atoms in the molecule.

  15. Stable isotope dilution gas chromatography-mass spectrometry for quantification of thymoquinone in black cumin seed oil.

    PubMed

    Johnson-Ajinwo, Okiemute Rosa; Li, Wen-Wu

    2014-06-18

    Black cumin seed (Nigella sativa L.) is a widely used spice and herb, where thymoquinone (2-isopropyl-5-methyl-1,4-benzoquinone) is the major bioactive compound. Here, a stable isotope dilution (SID) gas chromatography-mass spectrometry (GC-MS) technique was developed for the quantification of thymoquinone. A doubly deuterated thymoquinone ([(2)H2]-thymoquinone) was synthesized for the first time with more than 93% deuteration degree shown by mass spectrometry and proton nuclear magnetic resonance ((1)H NMR). This compound was used as an internal standard for the quantification of thymoquinone using a SID GC-MS method. The validation experiment showed a recovery rate of 99.1 ± 1.1% relative standard deviation (RSD). Standard addition and external calibration methods have also been used to quantify thymoquinone, which cross-validated the developed stable isotope dilution assay (SIDA). In comparison to external calibration and standard addition methods, the SIDA method is robust and accurate. The concentration of thymoquinone in five marketed black cumin seed oils ranged between 3.34 and 10.8 mg/mL by use of SID GC-MS.

  16. Comparative Analysis of Mass Spectral Similarity Measures on Peak Alignment for Comprehensive Two-Dimensional Gas Chromatography Mass Spectrometry

    PubMed Central

    2013-01-01

    Peak alignment is a critical procedure in mass spectrometry-based biomarker discovery in metabolomics. One of peak alignment approaches to comprehensive two-dimensional gas chromatography mass spectrometry (GC×GC-MS) data is peak matching-based alignment. A key to the peak matching-based alignment is the calculation of mass spectral similarity scores. Various mass spectral similarity measures have been developed mainly for compound identification, but the effect of these spectral similarity measures on the performance of peak matching-based alignment still remains unknown. Therefore, we selected five mass spectral similarity measures, cosine correlation, Pearson's correlation, Spearman's correlation, partial correlation, and part correlation, and examined their effects on peak alignment using two sets of experimental GC×GC-MS data. The results show that the spectral similarity measure does not affect the alignment accuracy significantly in analysis of data from less complex samples, while the partial correlation performs much better than other spectral similarity measures when analyzing experimental data acquired from complex biological samples. PMID:24151524

  17. Rapid screening natural-origin lipase inhibitors from hypolipidemic decoctions by ultrafiltration combined with liquid chromatography-mass spectrometry.

    PubMed

    Xiao, Shun; Yu, Runru; Ai, Ni; Fan, Xiaohui

    2015-02-01

    Lipase inhibitors generate hypolipidemic effect that is helpful to control or treat some obesity diseases by inactivating catalytic activity of human pancreatic lipase, a key enzyme involved in triglyceride hydrolysis in vivo. Many traditional Chinese medicine (TCM) formulae have been effectively used to treat obesity and other fat related diseases for centuries and modern biological experiments demonstrate therapeutic effect of these formulae can be linked to their lipid-lowering capability in blood. These observations suggest that these hypolipidemic decoctions (HDs) could be a promising resource of natural-origin lipase inhibitors. This work described a rapid approach for screening lipase inhibitors from four widely used HDs, including Wu-Ling-San (WLS), Ze-Xie decoction (ZX), Xiao-Xian-Xiong decoction (XXX) and Xiao-Chai-Hu decoction (XCH), by ultrafiltration combing with high performance liquid chromatography-mass spectrometry (HPLC-MS). Our results showed sixteen natural-origin lipase inhibitors were discovered and identified by high resolution and multistage mass spectrometry. Inhibitory activities of two compounds were confirmed by a functional assay of lipase, which validated the reliability of our approach. Molecular docking simulation was then performed to investigate potential mechanism of action for these compounds. Together we present an efficient method for rapid screening lipase inhibitors from complex natural products, which can be easily accommodated to other important enzymatic system with therapeutic values.

  18. Simultaneous analysis of antioxidants and preservatives in cosmetics by supercritical fluid extraction combined with liquid chromatography-mass spectrometry.

    PubMed

    Lee, Maw-Rong; Lin, Chueh-Yu; Li, Zu-Guang; Tsai, Tzu-Feng

    2006-07-07

    This study evaluated supercritical fluid extraction (SFE) combined with liquid chromatography-mass spectrometry (LC-MS) to determine trace preservatives and antioxidants including methylparaben (MP), ethylparaben (EP), propylparaben (PP), butylparaben (BP), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), alpha-tocopherol (alpha-t) and alpha-tocopherol acetate (alpha-ta) in cosmetic products. A supercritical fluid extraction procedure was used to isolate four paraben preservatives and four antioxidants from the cosmetic matrix before quantitative analysis. The optimum extraction condition was performed with static extraction for 5 min, then dynamic extraction for 20 min by using carbon dioxide supercritical fluid at 14,000 kPa and 65 degrees C. Methanol was used as collection solvent and the sea sand was chosen as a filling material. The analytes were separated on a C18 reversed-phase column using methanol-water as mobile phase and quantified by measuring its mass spectrometry. The linearity range is from 10 to 20,000 ng/g with RSD values below 18%. Detection limits are achieved at the level of 4.7-142 ng/g. It was successfully applied to the determination of paraben preservatives and antioxidants in cosmetics without tedious pretreatment.

  19. SPECIATION OF SUBSURFACE CONTAMINANTS BY CONE PENETROMETRY GAS CHROMATOGRAPHY/MASS SPECTROMETRY. (R826184)

    EPA Science Inventory

    A thermal extraction cone penetrometry gas chroma tography/mass spectrometry system (TECP GC/MS) has been developed to detect subsurface contaminants in situ. The TECP can collect soil-bound organics up to depths of 30 m. In contrast to traditional cone penetrometer sample collec...

  20. Identification of bupropion urinary metabolites by liquid chromatography/mass spectrometry.

    PubMed

    Petsalo, Aleksanteri; Turpeinen, Miia; Tolonen, Ari

    2007-01-01

    Human urinary metabolism of the antidepressant bupropion was studied using liquid chromatography/time-of-flight mass spectrometry (LC/TOFMS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS). A total of 20 metabolites were detected and identified. The phase I metabolism included formation of morpholinohydroxybupropion, threo- and erythrohydrobupropion, aromatic hydroxylation, butyl group hydroxylation with ketone hydrogenation and dihydroxylation. These metabolites were detected either as the free form or as glucuronide and/or sulphate conjugates. In addition also m-chlorohippuric acid was detected. Of the phase I metabolites, a dihydroxylation to the aromatic ring and to the methyl group in the middle of the substrate molecule was reported here for the first time, as well as eight of the glucuronide conjugates (to hydroxy, dihydroxy, hydroxy and hydrogenation metabolites) and three of the sulphate conjugates (to aromatic hydroxy and hydroxy and hydrogenation metabolites). Copyright (c) 2007 John Wiley & Sons, Ltd.

  1. Development of thermal desorption gas chromatography/mass spectrometry as a rapid method for ambient particulate characterization

    NASA Astrophysics Data System (ADS)

    Sheya, Sue Anne N.

    A direct thermal desorption gas chromatography/mass spectrometry (TD GC/MS) method for air particulate matter (PM) analysis of volatile and semivolatile organic compounds was investigated. This technique uses a specially designed microdesorption GC inlet utilizing an inductively heated ferromagnetic foil with a Curie point temperature suitable for desorption, which can accommodate microgram amounts of material deposited on a thin strip of quartz fiber filter. Liquid or solid samples can be rapidly desorbed within 10 s at 315°C, followed by 30--40 min of chromatography time. The results obtained by this technique were found to be statistically equivalent to those obtained by the conventional solvent extraction gas chromatography/mass spectrometry (SX GC/MS) method for analysis of aromatic and n alkane standards, single source soot particles, and PM 10 filter samples. Correlations between injecting an extract, desorbing an extract, and desorbing particles averaged R = 0.94, with a three way correlation averaging R = 0.97. High volume sampling conducted at 12 spatially distributed sites located along the US/Mexican border of the El Paso/Juarez metroplex supplied 24h PM 10 filters for an investigation combining thermal desorption with a rapid online chemical derivatization procedure, and multivariate methods of source attribution using principal component and canonical correlation analysis of the resultant chemical markers. Four major combustion related PM emission sources were revealed at these sites: automotive, waste burning, biomass burning and meat cooking. A second investigation conducted in the same area used mediumvolume sampling to collect 2 h timeresolved PM 10 receptor samples for TD GC/MS analysis. Additionally, 2 h samples for inorganic analysis, multichannel particle size distribution measurements, and meteorological data were collected enabling generation of circadian PM multicharacterization profiles. Factor analysis based receptor modeling using

  2. A multi-fiber handling device for in vivo solid phase microextraction-liquid chromatography-mass spectrometry applications.

    PubMed

    Cudjoe, Erasmus; Pawliszyn, Janusz

    2012-04-06

    Solid phase microextraction, an in vivo and ex vivo sample preparation method, continues to capture growing interest among researchers for bioanalytical applications. When coupled with liquid chromatography mass spectrometry, the procedure often involves large numbers of fibers in, for example, both pharmacokinetic and pharmadynamic studies as well as other bioapplications. In this regard, appropriate and adequate precaution will be critical in preventing the fibers firstly from any possible external contamination and damage to maintain high analytical data integrity. In addition, improving the offline desorption of fibers specifically for in vivo SPME will not only help in improving data quality, but will also significantly decrease the overall analysis time. This article introduces a prototype multi-fiber handling device capable of simultaneous extraction/desorption of multiple solid phase microextraction (SPME) fibers on a 96-deep well plate format. This device thus provides an alternative approach to improving higher sample throughput for in vivo SPME liquid chromatography mass spectrometry applications. The portable design of the device ensures effective protection and prevention of fibers against damage and possible contamination and thus maintains analytical data reliability. To ensure its suitability for parallel extraction/desorption, the device was carefully evaluated using four benzodiazepines (diazepam, nordiazepam, oxazepam and lorazepam) as model drugs by monitoring inter- and intra-well variability. The effect of agitation speed on data precision and accuracy, effect of device weight on data precision, and comparison of the overall performance of the device with traditional manual desorption approach were also assessed. Results obtained from evaluation of the device with particular focus on the desorption process indicated that the weight of the device has no effect on the reliability and reproducibility of data acquired using the device. The average

  3. Enantioselective gas chromatography/mass spectrometry of methylsulfonyl PCBs with application to arctic marine mammals.

    PubMed

    Wiberg, K; Letcher, R; Sandau, C; Duffe, J; Norstrom, R; Haglund, P; Bidleman, T

    1998-09-15

    Four different commercially available cyclodextrin (CD) capillary gas chromatography (GC) columns were tested for the enantioselective separation of nine environmentally persistent atropisomeric 3- and 4-methylsulfonyl PCBs (MeSO2-CBs). The selected columns contained cyclodextrins with various cavity diameters (beta- or gamma-CD), which were methylated and/or tert-butyldimethylsilylated (TBDMS) in the 2,3,6-O-positions. The beta-CD column with TBDMS substituents in all of the 2,3,6-O-positions was by far the most selective column for the MeSO2-CBs tested. Enantiomers of congeners with 3-MeSO2 substitution were more easily separated than those with 4-MeSO2 substitution. The separation also seemed to be enhanced for congeners with the chlorine atoms on the non-MeSO2-containing ring and clustered on one side of the same ring. The 2,3-di-O-methyl-6-O-TBDMS-beta-CD was found to give somewhat better selectivity than the corresponding gamma-CD, in comparison between the two columns, which were identical in all other respects. Enantioselective analysis of arctic ringed seal (Phoca hispida) and polar bear (Ursus maritimus) adipose tissue revealed a strong dominance of certain enantiomers. For example, the enantiomer ratio (ER) of 3-MeSO2-CB149 was 0.32 and < 0.1 in ringed seal blubber and polar bear fat, respectively. These low ER values are indicative of highly enantioselective formation, enantioselective metabolism, enantioselective transport across cell membranes, or a combination of the three in both species. Comparable results for the enantiomeric analysis of MeSO2-CBs in biotic tissue extracts were obtained using two highly selective mass spectrometric techniques, ion trap mass spectrometry/mass spectrometry and electron capture negative ion low-resolution mass spectrometry.

  4. Supercritical-fluid extraction and chromatography-mass spectrometry for analysis of mycotoxins

    SciTech Connect

    Smith, R.D.; Udseth, H.R.

    1982-07-01

    The use of direct supercritical-fluid injection-mass spectrometry for the rapid analysis of mycotoxins of the tricothecene group is demonstrated. A solution containing diacetoxyscirpenol or T-2 toxin is injected into a fluid consisting primarily of pentane or carbon dioxide and is rapidly brought to supercritical conditions. Direct injection of the fluid stream into a chemical ionization source allows thermally labile compounds to be analyzed. Under these conditions trichothecene mass spectra showing significant (M + 1)/sup +/ ions and distinctive fragmentation patterns are obtained. Detection limits are in the subnanogram range. Direct analysis from complex substrates using selective supercritical-fluid extraction is proposed. 4 figures.

  5. Determination of histamine in tomatoes by liquid chromatography/mass spectrometry.

    PubMed

    Bolygo, E; Cooper, P A; Jessop, K M; Moffatt, F

    2000-01-01

    The histamine level in tomato fruits and pastes was determined by 2 orthogonal techniques as a means of comparing accuracy. Close statistical agreement was found between assays for free histamine by capillary electrophoresis (with UV absorbance detection), and for the dansyl derivative by reversed-phase liquid chromatography (LC). Both techniques have adequate sensitivity for the analysis of endogenous histamine in tomatoes, but LC/electrospray tandem mass spectrometry was more sensitive by at least an order of magnitude, down to a level of 0.05 mg/kg.

  6. Different headspace solid phase microextraction--gas chromatography/mass spectrometry approaches to haloanisoles analysis in wine.

    PubMed

    Jeleń, Henryk H; Dziadas, Mariusz; Majcher, Małgorzata

    2013-10-25

    Three approaches in determination of six haloanisoles (2,4,6-trichloroanisole, 2,3,4-trichloroanisole, 2,3,6-trichloroanisole, tetrachloroanisole, pentachloroanisole and 2,4,6-tribromoanisole) in wine were compared. Comprehensive gas chromatography - time of flight mass spectrometry (GC×GC-ToF-MS) was described for the first time for this application and compared to gas chromatography-tandem mass spectrometry (GC-MS/MS) using triple quadrupole instrument. These techniques were compared with "standard" analytical approach using GC-MS(SIM). SPME method was developed and used for all separation methods (DVB/PDMS fiber, 70 °C, 30%NaCl, 20 min extraction). Extraction dependence on matrix was discussed using model wines with different ethanol contents (8%, 12%, and 18%) as well as water and different wines (dry white, dry red and sweet liqueur), with the lowest sensitivities obtained for highest ethanol contents in model wine and for liqueur wine. Limits of detection for GC×GC-ToF-MS method were 0.09-2.92 ng/L depending on the examined compound and matrix (compared to 0.1-13.3 ng/L obtained using GC/MS(SIM)). For GC-MS/MS method lower detection limits were achieved than for the GC×GC method (0.01-0.1 ng/L), however comprehensive gas chromatography-mass spectrometry provides full spectral information on analyzed compounds. Both methods had limits of detection far below odor thresholds of haloanisoles in wine, good linearity up to 2000 ng/L tested and good precision, what makes them suitable for analysis of these compounds in low ppt levels. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. High Throughput Quantitative Analysis of Serum Proteins Using Glycopeptide Capture and Liquid Chromatography Mass Spectrometry

    SciTech Connect

    Zhang, Hui; Yi, Eugene C.; Li, Xiao-jun; Mallick, Parag; Kelly-Spratt, Karen S.; Masselon, Christophe D.; Camp, David G.; Smith, Richard D.; Kemp, Christopher J.; Aebersold, Reudi

    2005-02-01

    It is expected that the composition of the serum proteome can provide valuable information about the state of the human body in health and disease and that this information can be extracted via quantitative proteomic measurements. Suitable proteomic techniques need to be sensitive, reproducible, and robust to detect potential biomarkers below the level of highly expressed proteins, generate data sets that are comparable between experiments and laboratories, and have high throughput to support statistical studies. Here we report a method for high throughput quantitative analysis of serum proteins. It consists of the selective isolation of peptides that are N-linked glycosylated in the intact protein, the analysis of these now deglycosylated peptides by liquid chromatography electrospray ionization mass spectrometry, and the comparative analysis of the resulting patterns. By focusing selectively on a few formerly N-linked glycopeptides per serum protein, the complexity of the analyte sample is significantly reduced and the sensitivity and throughput of serum proteome analysis are increased compared with the analysis of total tryptic peptides from unfractionated samples. We provide data that document the performance of the method and show that sera from untreated normal mice and genetically identical mice with carcinogen-induced skin cancer can be unambiguously discriminated using unsupervised clustering of the resulting peptide patterns. We further identify, by tandem mass spectrometry, some of the peptides that were consistently elevated in cancer mice compared with their control littermates.

  8. Deamidation in ricin studied by capillary zone electrophoresis- and liquid chromatography-mass spectrometry.

    PubMed

    Bergström, Tomas; Fredriksson, Sten-Åke; Nilsson, Calle; Åstot, Crister

    2015-01-01

    Deamidation in ricin, a toxin present in castor beans from the plant Ricinus communis, was investigated using capillary zone electrophoresis (CZE) and liquid chromatography coupled to high resolution mass spectrometry. Potential sites for deamidation, converting asparagine (Asn) into aspartic or isoaspartic acid (Asp or isoAsp), were identified in silico based on the protein sequence motifs and tertiary structure. In parallel, CZE- and LC-MS-based screening were performed on the digested toxin to detect deamidated peptides. The use of CZE-MS was critical for the separation of small native/deamidated peptide pairs. Selected peptides were subjected to a detailed analysis by tandem mass spectrometry to verify the presence of deamidation and determine its exact position. In the ricin preparation studied, deamidation was confirmed and located to three asparagine residues: Asn54 in the A-chain, and Asn42 and Asn60 in the B-chain. Possible in vitro deamidation occurring during sample preparation was monitored using a synthetic peptide with a known and rapid rate of deamidation. Finally, we showed that the isoelectric diversity previously reported in ricin is related to the level of deamidation.

  9. Statistical quality assessment and outlier detection for liquid chromatography-mass spectrometry experiments

    PubMed Central

    Schulz-Trieglaff, Ole; Machtejevas, Egidijus; Reinert, Knut; Schlüter, Hartmut; Thiemann, Joachim; Unger, Klaus

    2009-01-01

    Background Quality assessment methods, that are common place in engineering and industrial production, are not widely spread in large-scale proteomics experiments. But modern technologies such as Multi-Dimensional Liquid Chromatography coupled to Mass Spectrometry (LC-MS) produce large quantities of proteomic data. These data are prone to measurement errors and reproducibility problems such that an automatic quality assessment and control become increasingly important. Results We propose a methodology to assess the quality and reproducibility of data generated in quantitative LC-MS experiments. We introduce quality descriptors that capture different aspects of the quality and reproducibility of LC-MS data sets. Our method is based on the Mahalanobis distance and a robust Principal Component Analysis. Conclusion We evaluate our approach on several data sets of different complexities and show that we are able to precisely detect LC-MS runs of poor signal quality in large-scale studies. PMID:19351414

  10. Automation of solid-phase microextraction-gas chromatography-mass spectrometry extraction of eucalyptus volatiles.

    PubMed

    Zini, Cláudia A; Lord, Heather; Christensen, Eva; de, Assis Teotĵnio F; Caramão, Elina B; Pawliszyn, Janusz

    2002-03-01

    Solid-phase microextraction (SPME) coupled with gas chromatography (GC)-ion-trap mass spectrometry (ITMS) is employed to analyze fragrance compounds from different species of eucalyptus trees: Eucalyptus dunnii, Eucalyptus saligna, Eucalyptus grandis, and hybrids of other species. The analyses are performed using an automated system for preincubation, extraction, injection, and analysis of samples. The autosampler used is a CombiPAL and has much flexibility for the development of SPME methods and accommodates a variety of vial sizes. For automated fragrance analysis the 10- and 20-mL vials are the most appropriate. The chromatographic separation and identification of the analytes are performed with a Varian Saturn 4D GC-ITMS using an HP-5MS capillary column. Several compounds of eucalyptus volatiles are identified, with good reproducibility for both the peak areas and retention times. Equilibrium extraction provides maximal sensitivity but requires additional consideration for the effect of carryover. Preequilibrium extraction allows good sensitivity with minimal carryover.

  11. First screening method for the simultaneous detection of seven allergens by liquid chromatography mass spectrometry.

    PubMed

    Heick, J; Fischer, M; Pöpping, B

    2011-02-18

    The development of a multi-method for the detection of seven allergens based on liquid chromatography and triple-quadrupole tandem mass spectrometry in multiple reaction mode is described. It is based on extraction of the allergenic proteins from a food matrix, followed by enzymatic digestion with trypsin. The chosen marker peptides were implemented into one method that is capable of the simultaneous detection of milk, egg, soy, hazelnut, peanut, walnut and almond. This method has been used to detect all seven allergenic commodities from incurred reference bread material, which was baked according to a standard recipe from the baking industry. Detected concentrations ranged from 10 to 1000 μg/g, demonstrating that the mass spectrometric based method is a useful tool for allergen screening.

  12. Impact of Pharmaceutical Impurities in Ecstasy Tablets: Gas Chromatography-Mass Spectrometry Study.

    PubMed

    Jalali, Amir; Hatamie, Amir; Saferpour, Tahere; Khajeamiri, Alireza; Safa, Tahere; Buazar, Foad

    2016-01-01

    In this study, a simple and reliable method by gas chromatograph-mass spectrometry (GC-MS) was developed for the fast and regular identification of 3, 4-MDMA impurities in ecstasy tablets. In so doing, 8 samples of impurities were extracted by diethyl ether under alkaline condition and then analyzed by GC-MS. The results revealed high MDMA levels ranging from 37.6% to 57.7%. The GC-MS method showed that unambiguous identification can be achieved for MDMA from 3, 4-methylenedioxyamphetamine (MDA), Amphetamine (AM), methamphetamine (MA) and ketamine (Keta) compounds, respectively. The experimental results indicated the acceptable time window without interfering peaks. It is found that GC-MS was provided a suitable and rapid identification approach for MDMA (Ecstacy) tablets, particularly in the Forensic labs. Consequently, the intense MDMA levels would support the police to develop a simple quantification of impurity in Ecstasy tablets.

  13. Impact of Pharmaceutical Impurities in Ecstasy Tablets: Gas Chromatography-Mass Spectrometry Study

    PubMed Central

    Jalali, Amir; Hatamie, Amir; Saferpour, Tahere; Khajeamiri, Alireza; Safa, Tahere; Buazar, Foad

    2016-01-01

    In this study, a simple and reliable method by gas chromatograph–mass spectrometry (GC–MS) was developed for the fast and regular identification of 3, 4-MDMA impurities in ecstasy tablets. In so doing, 8 samples of impurities were extracted by diethyl ether under alkaline condition and then analyzed by GC–MS. The results revealed high MDMA levels ranging from 37.6% to 57.7%. The GC-MS method showed that unambiguous identification can be achieved for MDMA from 3, 4-methylenedioxyamphetamine (MDA), Amphetamine (AM), methamphetamine (MA) and ketamine (Keta) compounds, respectively. The experimental results indicated the acceptable time window without interfering peaks. It is found that GC-MS was provided a suitable and rapid identification approach for MDMA (Ecstacy) tablets, particularly in the Forensic labs. Consequently, the intense MDMA levels would support the police to develop a simple quantification of impurity in Ecstasy tablets. PMID:27610162

  14. Electrochemical oxidation and protein adduct formation of aniline: a liquid chromatography/mass spectrometry study.

    PubMed

    Melles, Daniel; Vielhaber, Torsten; Baumann, Anne; Zazzeroni, Raniero; Karst, Uwe

    2012-04-01

    Historically, skin sensitization tests are typically based on in vivo animal tests. However, for substances used in cosmetic products, these tests have to be replaced according to the European Commission regulation no. 1223/2009. Modification of skin proteins by electrophilic chemicals is a key process associated with the induction of skin sensitization. The present study investigates the capabilities of a purely instrumental setup to determine the potential of commonly used non-electrophilic chemicals to cause skin sensitization by the generation of electrophilic species from the parent compound. In this work, the electrophiles were generated by the electrochemical oxidation of aniline, a basic industrial chemical which may also be released from azo dyes in cosmetics. The compound is a known sensitizer and was oxidized in an electrochemical thin-layer cell which was coupled online to electrospray ionization-mass spectrometry. The electrochemical oxidation was performed on a boron-doped diamond working electrode, which is able to generate hydroxyl radicals in aqueous solutions at high potentials. Without any pretreatment, the oxidation products were identified by electrospray ionization/time-of-flight mass spectrometry (ESI-ToF-MS) using their exact masses. A mass voltammogram was generated by plotting the obtained mass spectra against the applied potential. Oligomerization states with up to six monomeric units in different redox states of aniline were observed using this setup. This approach was extended to generate adducts between the oxidation products of aniline and the tripeptide glutathione. Two adducts were identified with this trapping experiment. Protein modification was carried out subsequently: Aniline was oxidized at a constant potential and was allowed to react with β-lactoglobulin A (β-LGA) or human serum albumin (HSA), respectively. The generated adducts were analyzed by liquid chromatography coupled to ESI-ToF-MS. For both β-LGA and HSA, aniline

  15. Analysis of vitamin D and its metabolites using thermospray liquid chromatography/mass spectrometry.

    PubMed

    Watson, D; Setchell, K D; Ross, R

    1991-07-01

    A new method is described for the analysis of vitamin D and its metabolites utilizing thermospray (TSP) mass spectrometry as an on-line detector for high performance liquid chromatography. Ionization conditions were optimized for use with isocratic reversed phase chromatography. TSP mass spectrometry was employed in series with a UV absorbance detector to facilitate comparisons between the two methods of detection. Positive ion TSP mass spectra were recorded for vitamin D2, vitamin D3, 25-hydroxyvitamin D3 (25(OH)D3), 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and 24,25-dihydroxyvitamin D3 (24,25(OH)2D3). The spectra contained protonated molecular ions, ammonium adduct ions and fragment ions due to the loss of one or more molecules of water. A comparison of quantitative precision was made by determining UV absorbance and TSP standard curves for vitamin D3 using two different methods: (1) External standard method with post-column (post UV detector) addition of ammonium acetate. (2) As (1) but using the method of internal standards with a closely eluting internal standard (vitamin D2). In each case the quantitative precision (correlation coefficient) for UV absorbance detection was superior owing to intrinsic instability of the TSP ion beam. A stable isotopically labelled internal standard was employed in the development of an assay for 1,25(OH)2D3. The assay was used to quantify in vitro enzymic conversion of 25(OH)D3 to 1,25(OH)2D3 in guinea pig and sheep renal mitochondrial incubations. TSP LC/MS was also applied to analysis of an extract of human blood plasma in which D3 and each of its principal metabolites were identified in a single analysis.

  16. Integration of electrochemistry with ultra-performance liquid chromatography/mass spectrometry.

    PubMed

    Cai, Yi; Zheng, Qiuling; Liu, Yong; Helmy, Roy; Loo, Joseph A; Chen, Hao

    2015-01-01

    This study presents the development of ultra-performance liquid chromatography (UPLC) mass spectrometry (MS) combined with electrochemistry (EC) for the first time and its application for the structural analysis of proteins/peptides that contain disulfide bonds. In our approach, a protein/peptide mixture sample undergoes a fast UPLC separation and subsequent electrochemical reduction in an electrochemical flow cell followed by online MS and tandem mass spectrometry (MS/MS) analyses. The electrochemical cell is coupled to the mass spectrometer using our recently developed desorption electrospray ionization (DESI) interface. Using this UPLC/EC/DESI-MS method, peptides that contain disulfide bonds can be differentiated from those without disulfide bonds, as the former are electroactive and reducible. MS/MS analysis of the disulfide-reduced peptide ions provides increased information on the sequence and disulfide-linkage pattern. In a reactive DESI- MS detection experiment in which a supercharging reagent was used to dope the DESI spray solvent, increased charging was obtained for the UPLC-separated proteins. Strikingly, upon online electrolytic reduction, supercharged proteins (e.g., α-lactalbumin) showed even higher charging, which will be useful in top- down protein structure MS analysis as increased charges are known to promote protein ion dissociation. Also, the separation speed and sensitivity are enhanced by approximately 1(~)2 orders of magnitude by using UPLC for the liquid chromatography (LC)/EC/MS platform, in comparison to the previously used high- performance liquid chromatography (HPLC). This UPLC/EC/DESI-MS method combines the power of fast UPLC separation, fast electrochemical conversion, and online MS structural analysis for a potentially valuable tool for proteomics research and bioanalysis.

  17. Biosynthesis of Gold Nanoparticles and Identification of Capping Agent Using Gas Chromatography-Mass Spectrometry and Matrix Assisted Laser Desorption Ionization-Mass Spectrometry.

    PubMed

    Karthick, V; Kumar, V Ganesh; Dhas, T Stalin; Govindaraju, K; Sinha, Sweta; Singaravelu, G

    2015-06-01

    In the present study, gold nanoparticles (AuNPs) were synthesized using leaf extract of Syzygium jambolanum and capping agent has been explored. The synthesized AuNPs have been characterized using UV-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), high resolution transmission electron microscopy (HRTEM) and atomic force microscopic (AFM) analysis. The AuNPs show intense surface plasmon resonance (SPR) band at 528 nm and were found to be spherical and hexagonal in shape with particle size ranging from 20-30 nm. Transmission electron microscopy and atomic force microscopy were used to analyze the surface morphology of synthesized AuNPs. The capping ligand has been evaluated using matrix assisted laser desorption ionization-mass spectrometry (MALDI-MS) and gas chromatography-mass spectrometry (GC-MS) analysis.

  18. Simultaneous Determination of 10 Photoinitiators in Milk by Solid-Phase Microextraction Coupled with Gas Chromatography/Mass Spectrometry.

    PubMed

    Liu, Pengyan; Zhao, Chunxia; Zhang, Yajing; Chen, Yanjie

    2016-05-01

    Photoinitiators (PIs) are widely used in food packaging materials, can migrate easily from packaging materials to food, and cause food contamination. It is essential to establish a method of determining PIs residues in food. A new method for simultaneously determining 10 kinds of PIs in milk has been established by using solid-phase microextraction (SPME) combined with a simple method of protein precipitation as the pretreatment approach and gas chromatography/mass spectrometry as the detecting technique. The limits of detection for 10 PIs in different milks were between 0.05 and 1.4 μg/L (skimmed milk), between 0.07 and 2.2 μg/L (semi-skimmed milk), between 0.11 and 4.4 μg/L (whole milk), respectively. The recoveries were from 71.5% to 133.5%, and the relative standard deviations were less than 15%. Twelve kinds of packed milk with different brands and fat contents were determined using this method.

  19. A fast liquid chromatography-mass spectrometry (LC-MS) method for quantification of major polar metabolites in plants.

    PubMed

    Liu, Zhiqian; Rochfort, Simone

    2013-01-01

    Current liquid chromatography (LC) based methods for the analysis of polar plant metabolites require multiple runs using complex mobile phases and a combination of different columns. Here we describe a fast liquid chromatography-mass spectrometry (LC-MS) method for the determination of major polar metabolites in plants that requires only a single run using a single column. The method takes advantage of the ability to acquire both positive and negative data in an ion trap mass spectrometer (MS) and also the accurate mass capability of the orbitrap MS. The separation of polar compounds is achieved with a polar, reversed-phase column (Synergi Hydro-RP). A single analysis with a 25min runtime is able to reliably determine the level of nearly all essential amino acids, several major organic acids and several major sugars in plant materials, as exemplified by analysis of a perennial ryegrass extract. The level of detection on column was below 0.1ng (average 0.03ng) for most amino acids, below 5ng (average 2.3ng) for organics acids and below 1ng (average 0.64ng) for sugars. The levels of quantified metabolites in ryegrass varied from 22μg/g dry weight for histidine to 41mg/g dry weight for sucrose.

  20. [Structural characterization of Astragalus polysaccharides using partial acid hydrolysis-hydrophilic interaction liquid chromatography-mass spectrometry].

    PubMed

    Liang, Tu; Fu, Qing; Xin, Huaxia; Li, Fangbing; Jin, Yu; Liang, Xinmiao

    2014-12-01

    Water-soluble polysaccharides from traditional Chinese medicine (TCM) have properties of broad-spectrum treatment and low toxicity, making them as important components in natural medicines and health products. In order to solve the problem of polysaccharides characterization caused by their complex structures, a "bottom-up" approach was developed to complete the characterization of polysaccharides from Astragalus. Firstly, Astragalus pieces were extracted with hot water and then were precipitated by ethanol to obtain Astragalus polysaccharides. Secondly, a partial acid hydrolysis method was carried out and the effects of time, acid concentration and temperature on hydrolysis were investigated. The degree of hydrolysis increased along with the increase of hydrolysis time and acid concentration. The temperature played a great role in the hydrolysis process. No hydrolysis of the polysaccharides occurred at low temperature, while the polysaccharides were almost hydrolyzed to monosaccharide at high temperature. Under the optimum hydrolysis conditions (4 h, 1.5 mol/L trifluoroacetic acid, and 80 °C), Astragalus polysaccharides were hydrolyzed to characteristic oligosaccharide fragments. At last, a hydrophilic liquid chromatography-mass spectrometry method was used for the separation and structural characterization of the polysaccharide hydrolysates. The results showed that the resulting polysaccharides were mainly 1--> 4 linear glucan, and gluco-oligosaccharides with the degrees of polymerization (DP) of 4 - 11 were obtained after partial acid hydrolysis. The significance of this study is that it is the guidance for the characterization of other TCM polysaccharides.

  1. Gas chromatography-mass spectrometry analysis of effects of dietary fish oil on total fatty acid composition in mouse skin

    PubMed Central

    Wang, Peiru; Sun, Min; Ren, Jianwei; Djuric, Zora; Fisher, Gary J.; Wang, Xiuli; Li, Yong

    2017-01-01

    Altering the fatty acid (FA) composition in the skin by dietary fish oil could provide therapeutic benefits. Although it has been shown that fish oil supplementation enhances EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) abundance in the skin, comprehensive skin FA profiling is needed. We established a gas chromatography-mass spectrometry method, which allows precise quantification of FA profile using small (<24 mm2 for mice and <12 mm2 for humans) skin specimens that can be readily obtained from live mice and humans. We determined mouse skin FA composition after 2, 4 and 8 weeks of consuming a control diet or a diet supplemented with fish oil. Fish oil markedly enhanced EPA and DHA in mouse skin within 2 weeks, and this increase plateaued after 4 weeks. The FA composition in mouse skin was different from that of serum, indicating that skin has homeostatic control of FA metabolism. Mice fed the control diet designed to simulate Western human diet displayed similar skin FA composition as that of humans. The present study presents a validated method for FA quantification that is needed to investigate the mechanisms of actions of dietary treatments in both mouse and human skin. PMID:28195161

  2. Determination of pesticides and veterinary drug residues in food by liquid chromatography-mass spectrometry: A review.

    PubMed

    Masiá, Ana; Suarez-Varela, Maria Morales; Llopis-Gonzalez, Agustin; Picó, Yolanda

    2016-09-14

    Monitoring of pesticides and veterinary drug residues is required to enforce legislation and guarantee food safety. Liquid chromatography-mass spectrometry (LC-MS) is the prevailing technique for assessing both types of residues because LC offers a versatile and universal separation mechanism suitable for non-gas chromatography (GC) amenable and the majority of GC-amenable compounds. This characteristic becomes more relevant when LC is coupled to MS because the high sensitivity and specificity of the detector allows to apply generic sample preparation procedures, which simultaneously extract a wide variety of residues with different physico-chemical properties. Determination of metabolites and degradation products, non-target suspected screening of an increasing number of residues, and even unknowns identification are also becoming inherent LC-MS advantages thanks to the latest advances. For routine analysis and, in particular, for official surveillance purposes in food control, analytical methods properly validated following strict guidelines are needed. After a brief introduction and an outline of the legislation applicable around the world, aspects such as improvement of specificity of high-throughput methods, resolution and mass accuracy of identification strategies and quantitative accuracy are critically reviewed in this article. In them, extraction, separation and determination are emphasized. The main objective is to offer an assessment of the state of the art and identify research needs and future trends in determining pesticide and veterinary drug residues in food by LC-MS.

  3. High-performance liquid chromatography-mass spectrometry profiling of phenolic compounds for evaluation of olive oil bitterness and pungency.

    PubMed

    Dierkes, Georg; Krieger, Sonja; Dück, Roman; Bongartz, Annette; Schmitz, Oliver J; Hayen, Heiko

    2012-08-08

    Bitterness and pungency are important parameters for olive oil quality. Therefore, two instrumental methods for evaluation of these taste attributes were developed. The first one is based on the photometric measurement of total phenolic compounds content, whereas the second one is based on the semiquantitative evaluation of hydrophilic compounds by high-performance liquid chromatography-mass spectrometry (HPLC-MS). Evaluation of total phenolic compounds content was performed by a modified method for the determination of the K(225) value using a more specific detection based on the pH value dependency of absorbance coefficients of phenols at λ = 274 nm. The latter method was not suitable for correct prediction, because no significant correlation between bitterness/pungency and total phenolic compounds content could be found. For the second method, areas of 25 peaks detected in 54 olive oil samples by a HPLC-MS profiling method were correlated with the bitterness and pungency by partial least-squares regression. Six compounds (oleuropein aglycon, ligstroside aglycon, decarboxymethyl oleuropein aglycon, decarboxymethyl ligstroside aglycon, elenolic acid, and elenolic acid methyl ester) show high correlations to bitterness and pungency. The computed model using these six compounds was able to predict bitterness and pungency of olive oil in the error margin of the sensory evaluation (±0.5) for most of the samples.

  4. [Determination of volatile N-nitrosamine compounds in salted aquatic products by gas chromatography-mass spectrometry].

    PubMed

    Zhao, Hua; Wang, Xiuyuan; Wang, Pingya; Zhou, Yong; Xue, Chaobo; Jiang, Lingbo

    2013-03-01

    An analytical method was developed for the determination of the extraction of volatile N-nitrosamine compounds including N-nitrosodimethylamine ( NDMA) , N-nitrosodiethylamine (NDEA), N-nitrosodipropylamine (NDPA), N-nitrosodibutylamine (NDBA), N-nitrosopiperidine (NPIP), and N-nitrosopyrrolidine (NPYR) from salted aquatic products by gas chromatography-mass spectrometry (GC-MS). In this experiment, the separation and detection conditions were optimized for different extraction methods, solid-phase extraction columns, and chromatographic columns. The results showed that the linear correlation coefficients (R2) were higher than 0. 999 8 within 10 - 1 000 micro g/L, and the reproducibilities were good with the - relative standard deviations (RSD) less than 8%. The recoveries were 79% - 105%. It is noted that this method for the determination of volatile N-nitrosamine compounds in salted aquatic products was much more sensitivity and with a lower detection limits (0. 05 micro g/kg except NDPA) than the previously reported methods. This proposed method is rapid and convenient for the determination, and easy for the operation. It is appropriate for the determination of volatile N-nitrosamine compounds in various salted aquatic products.

  5. Application of gas chromatography-mass spectrometry in analyzing pharmacokinetics and distribution of deltamethrin in miniature pig tissues.

    PubMed

    Zhu, Pan; Fan, Sai; Zou, Jian Hong; Miao, Hong; Li, Jing Guang; Zhang, Guo Wen; Wu, Yong Ning

    2014-06-01

    To characterize the pharmacokinetics and distribution profiles of deltamethrin in miniature pig tissues by gas chromatography-mass spectrometry (GC-MS). Pharmacokinetics and distribution of deltamethrin in blood and tissues of 30 miniature pigs were studied by GC-MS after oral administration of deltamethrin (5 mg/kg bw). Data were processed by 3P97 software. The serum deltamethrin level was significantly lower in tissues than in blood of miniature pigs. The AUC0-72 h, Cmax, of deltamethrin were 555.330 ± 316.987 ng h/mL and 17.861 ± 11.129 ng/mL, respectively. The Tmax, of deltamethrin was 6.004 ± 3.131 h. The metabolism of deltamethrin in miniature pigs is fit for a one-compartment model with a weighting function of 1/C2. Deltamethrin is rapidly hydrolyzed and accumulated in miniature pig tissues. Copyright © 2014 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

  6. Fundamental studies with a monodisperse aerosol-based liquid chromatography/mass spectrometry interface (MAGIC-LC/MS)

    SciTech Connect

    Browner, R.F.

    1990-10-01

    Accomplishments on the fundamental studies with a monodisperse aerosol-based liquid chromatography/mass spectrometry (LC/MS) interface during the period 1 December 1989 to 30 November 1990 are summarized. In order to determine the influence of temperature on the vaporization and decomposition properties of molecules, test have been carried out on both thermally stable and thermally labile molecules. The test compounds used were a series of polynuclear aromatic (PAH) compounds covering a wide range of molecular weights from two-ring naphthalene to twelve-ring perylene. The less thermally stable species examined were aldicarb, a highly thermally labile pesticide, and cholesterol, which readily loses water when subjected to high temperatures. A new, externally heated probe, which can be raised to temperatures as high as 500{degree}C was also used. Matrix loading effects for a range of surface active and non-surface active compounds in three different matrices: glycerol, 3-nitrobenzyl alcohol, and thioglycerol for fast atom bombardment (FAB) particle beam LC/MS have been studied. The time dependence of FAB spectra generation in the particle beam system has been examined and contrasted with ion generation in normal probe FAB work. Future FAB LC/MS research is outlined. 3 refs. (BM)

  7. Analytical Approaches Based on Gas Chromatography Mass Spectrometry (GC/MS) to Study Organic Materials in Artworks and Archaeological Objects.

    PubMed

    Bonaduce, Ilaria; Ribechini, Erika; Modugno, Francesca; Colombini, Maria Perla

    2016-02-01

    Gas chromatography/mass spectrometry (GC/MS), after appropriate wet chemical sample pre-treatments or pyrolysis, is one of the most commonly adopted analytical techniques in the study of organic materials from cultural heritage objects. Organic materials in archaeological contexts, in classical art objects, or in modern and contemporary works of art may be the same or belong to the same classes, but can also vary considerably, often presenting different ageing pathways and chemical environments. This paper provides an overview of the literature published in the last 10 years on the research based on the use of GC/MS for the analysis of organic materials in artworks and archaeological objects. The latest progresses in advancing analytical approaches, characterising materials and understanding their degradation, and developing methods for monitoring their stability are discussed. Case studies from the literature are presented to examine how the choice of the working conditions and the analytical approaches is driven by the analytical and technical question to be answered, as well as the nature of the object from which the samples are collected.

  8. Quantification of phylloquinone and menaquinones in feces, serum, and food by high-performance liquid chromatography-mass spectrometry.

    PubMed

    Karl, J Philip; Fu, Xueyan; Dolnikowski, Gregory G; Saltzman, Edward; Booth, Sarah L

    2014-07-15

    Vitamin K, comprising phylloquinone (PK) and menaquinones (MKn), is a family of vitamers found in multiple biological and environmental matrices. Advancing emerging evidence for novel and distinct physiologic roles of these vitamers in human health and disease necessitates sensitive and selective methods for quantifying PK and MKn in these matrices. We developed a novel method employing high-performance liquid chromatography-mass spectrometry with atmospheric pressure chemical ionization (LC-APCI-MS) for simultaneous quantification of 11 vitamin K vitamers that can be applied in feces, serum and food. Minimal detectable concentrations of vitamin K vitamers ranged from 1 pmol/g to 30 pmol/g. Limits of quantification ranged from 5 pmol/g to 90 pmol/g. Inter-assay and intra-assay variations were <17% and <8%, respectively, in food, and <12% and <8%, respectively, in feces. Recovery exceeded 80% for all vitamers in both food and feces. The method successfully quantified PK and MKn concentrations in rat chow, feces and serum. In summary, this LC-APCI-MS method provides a sensitive and selective tool for quantifying vitamin K vitamers in feces, serum and food. This method can be applied in human and animal studies examining the role of vitamin K vitamers derived from the diet and gut bacteria synthesis in health and disease. Published by Elsevier B.V.

  9. Analysis of isotope ratios in vitamin K1 (phylloquinone) from human plasma by gas chromatography/mass spectrometry.

    PubMed

    Jones, Kerry S; Bluck, Leslie J C; Coward, W Andy

    2006-01-01

    Vitamin K(1) is a fat-soluble vitamin required for the gamma-carboxylation of vitamin K-dependent proteins. Recent work has suggested an important role for vitamin K(1) in bone health beyond its more established function in the control and regulation of blood coagulation. However, current UK recommended intakes do not reflect this recent evidence. The use of stable isotopes provides a powerful tool to investigate vitamin K kinetics, turnover and absorption in man, although published methods have reported difficulties in the extraction and analysis of isotope ratios of vitamin K in human plasma. In this paper, we report a new methodology for the extraction and measurement of isotope ratios in vitamin K(1). Sample clean-up is achieved with liquid-liquid extraction, enzyme hydrolysis with lipase and cholesterol esterase, and solid-phase extraction. Isotopic analysis of the pentafluoropropionyl derivative of vitamin K(1) is performed by gas chromatography/mass spectrometry (GC/MS). The limit of quantitation is equivalent to at least 0.3 nmol/L and the method is demonstrated to be linear over a range of enrichments. This method provides a robust alternative to previous work requiring the use of semi-preparative high-performance liquid chromatography (HPLC). Copyright (c) 2006 John Wiley & Sons, Ltd.

  10. [Fast analysis of common fatty acids in edible vegetable oils by ultra-performance convergence chromatography-mass spectrometry].

    PubMed

    Lin, Chunhua; Xie, Xianqing; Fan, Naili; Tu, Yuanhong; Chen, Yan; Liao, Weilin

    2015-04-01

    A fast analytical method for five common fatty acids in six edible vegetable oils was developed by ultra-performance convergence chromatography-mass spectrometry (UPC2-MS). The five fatty acids are palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid. Their contents in the corn oil, sunflower oil, soybean oil, tea oil, rapeseed oil and peanut oil were compared. The chromatographic separation was performed on an ACQUITY UPC2 BEH 2-EP column (100 mm x 2.1 mm, 1.7 µm) using the mobile phases of carbon dioxide and methanol/acetonitrile (1:1, v/v) with gradient elution. The separated compounds were detected by negative electrospray ionization ESF-MS. The results showed that the reasonable linearities were achieved for all the analytes over the range of 0.5-100 mg/L with the correlation coefficients (R2) of 0.9985-0.9998. The limits of quantification (S/N ≥ 10) of the five fatty acids were 0.15-0.50 mg/L. The recoveries of the five fatty acids at three spiked levels were in the range of 89.61%-108.50% with relative standard deviations of 0.69%-3.01%. The developed method showed high performance, good resolution and fast analysis for the underivatized fatty acids. It has been successfully used to detect the five fatty acids from corn oil, sunflower oil, soybean oil, tea oil rapeseed oil and peanut oil.

  11. A gas chromatography-mass spectrometry based study on urine metabolomics in rats chronically poisoned with hydrogen sulfide.

    PubMed

    Deng, Mingjie; Zhang, Meiling; Sun, Fa; Ma, Jianshe; Hu, Lufeng; Yang, Xuezhi; Lin, Guanyang; Wang, Xianqin

    2015-01-01

    Gas chromatography-mass spectrometry (GS-MS) in combination with multivariate statistical analysis was applied to explore the metabolic variability in urine of chronically hydrogen sulfide- (H2S-) poisoned rats relative to control ones. The changes in endogenous metabolites were studied by partial least squares-discriminate analysis (PLS-DA) and independent-samples t-test. The metabolic patterns of H2S-poisoned group are separated from the control, suggesting that the metabolic profiles of H2S-poisoned rats were markedly different from the controls. Moreover, compared to the control group, the level of alanine, d-ribose, tetradecanoic acid, L-aspartic acid, pentanedioic acid, cholesterol, acetate, and oleic acid in rat urine of the poisoning group decreased, while the level of glycine, d-mannose, arabinofuranose, and propanoic acid increased. These metabolites are related to amino acid metabolism as well as energy and lipid metabolism in vivo. Studying metabolomics using GC-MS allows for a comprehensive overview of the metabolism of the living body. This technique can be employed to decipher the mechanism of chronic H2S poisoning, thus promoting the use of metabolomics in clinical toxicology.

  12. Revisiting the Metabolism and Bioactivation of Ketoconazole in Human and Mouse Using Liquid Chromatography-Mass Spectrometry-Based Metabolomics.

    PubMed

    Kim, Ju-Hyun; Choi, Won-Gu; Lee, Sangkyu; Lee, Hye Suk

    2017-03-13

    Although ketoconazole (KCZ) has been used worldwide for 30 years, its metabolic characteristics are poorly described. Moreover, the hepatotoxicity of KCZ limits its therapeutic use. In this study, we used liquid chromatography-mass spectrometry-based metabolomics to evaluate the metabolic profile of KCZ in mouse and human and identify the mechanisms underlying its hepatotoxicity. A total of 28 metabolites of KCZ, 11 of which were novel, were identified in this study. Newly identified metabolites were classified into three categories according to the metabolic positions of a piperazine ring, imidazole ring, and N-acetyl moiety. The metabolic characteristics of KCZ in human were comparable to those in mouse. Moreover, three cyanide adducts of KCZ were identified in mouse and human liver microsomal incubates as "flags" to trigger additional toxicity study. The oxidation of piperazine into iminium ion is suggested as a biotransformation responsible for bioactivation. In summary, the metabolic characteristics of KCZ, including reactive metabolites, were comprehensively understood using a metabolomics approach.

  13. Validation of biomarkers for distinguishing Mycobacterium tuberculosis from non-tuberculous mycobacteria using gas chromatography-mass spectrometry and chemometrics.

    PubMed

    Dang, Ngoc A; Kuijper, Sjoukje; Walters, Elisabetta; Claassens, Mareli; van Soolingen, Dick; Vivo-Truyols, Gabriel; Janssen, Hans-Gerd; Kolk, Arend H J

    2013-01-01

    Tuberculosis (TB) remains a major international health problem. Rapid differentiation of Mycobacterium tuberculosis complex (MTB) from non-tuberculous mycobacteria (NTM) is critical for decisions regarding patient management and choice of therapeutic regimen. Recently we developed a 20-compound model to distinguish between MTB and NTM. It is based on thermally assisted hydrolysis and methylation gas chromatography-mass spectrometry and partial least square discriminant analysis. Here we report the validation of this model with two independent sample sets, one consisting of 39 MTB and 17 NTM isolates from the Netherlands, the other comprising 103 isolates (91 MTB and 12 NTM) from Stellenbosch, Cape Town, South Africa. All the MTB strains in the 56 Dutch samples were correctly identified and the model had a sensitivity of 100% and a specificity of 94%. For the South African samples the model had a sensitivity of 88% and specificity of 100%. Based on our model, we have developed a new decision-tree that allows the differentiation of MTB from NTM with 100% accuracy. Encouraged by these findings we will proceed with the development of a simple, rapid, affordable, high-throughput test to identify MTB directly in sputum.

  14. Gas chromatography-mass spectrometry and Raman imaging measurement of squalene content and distribution in human hair.

    PubMed

    Wu, Yan; Chen, Guoqiang; Ji, Chengdong; Hoptroff, Michael; Jones, Andrew; Collins, Luisa Z; Janssen, Hans-Gerd

    2016-03-01

    A sensitive and specific gas chromatography-mass spectrometry (GC-MS) method was developed and validated for the measurement of the squalene content from root to tip, in both Chinese black virgin and bleached hair. Deuterated squalene was used as the internal standard. For quantification, selective ion monitoring (SIM) at m/z 410.0 and 347.0 were monitored for squalene and deuterated squalene, respectively. Different methods for the extraction of squalene from ex vivo human hair were compared including organic solvent extraction and acid/alkali hydrolysis. The best extraction efficiency was obtained by using a mixed solvent consisting of chloroform:methanol = 2:1 (v:v). The linear range of squalene ran from 1.0 to 50.0 μg mL(-1). The limit of detection (LOD) was 0.10 μg mL(-1) (corresponding to 0.005 mg g(-1) in human hair), which enabled quantification of squalene in human hair at very low level. The recovery of squalene was 96.4 ± 1.46% (n = 3). Using the above-mentioned mixed solvent extraction, squalene content in human hair was successfully quantified from root to tip. Meanwhile, a Raman imaging method was developed to visualize the squalene distribution in Chinese white virgin hair from cuticle to medulla.

  15. Determination of alkylphenolic residues in fresh fruits and vegetables by extractive steam distillation and gas chromatography-mass spectrometry.

    PubMed

    Yang, Deng-Kai; Ding, Wang-Hsien

    2005-09-23

    This study describes a simple and sensitive method for determining the alkylphenolic compounds, 4-tert-octylphenol (4-t-OP), 4-nonylphenol isomers (4-NPs), and their monoethoxylates (4-t-OP1EO and 4-NP1EOs), in fresh fruits and vegetables. The method involves extracting a sample by a modified Nielson-Kryger steam distillation extraction using n-hexane for 1 h. The alkylphenolic compounds were identified and quantitated by gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode. Various pH values and amounts of NaCl added to the sample solution were evaluated as extraction conditions. The quantitation limit of this method was less than 0.2 ng/g in 10 g (fresh weight) of sample. Recovery of alkylphenolic compounds in spiked samples exceeded 64% while R.S.D. ranged from 1.0 to 9.8%. Alkylphenolic residues were detected in fresh fruits and vegetables at concentrations of 4-NPs and 4-t-OP from n.d. to 16 ng/g and from n.d. to 4.8 ng/g (fresh weight), respectively. NP1EO and OP1EO were always below the quantitation limit.

  16. Sensitive determination of bromate in ozonated and chlorinated water, and sea water by gas chromatography-mass spectrometry after derivatization.

    PubMed

    Shin, Ho-Sang

    2012-02-03

    A sensitive gas chromatographic method has been established for the determination of bromate in ozonated and chlorinated water, and in sea water. With acidic conditions, bromate reacts with chloride to form bromine, which reacts with 2,6-dialkylphenol to form 4-bromo-2,6-dialkylphenol. The organic derivative was extracted with ethyl acetate after quenching remaining oxidants with ascorbic acid, and then measured by gas chromatography-mass spectrometry (GC-MS). The lowest detection limit and limit of quantification of bromate in drinking water were 0.02 and 0.07 μg/L, respectively, and the calibration curve showed good linearity with r²=0.998. The 32 common ions did not interfere even when present in 100-fold excess over the bromated ion. The accuracy was in a range of 102-106% and the precision of the assay was less than 6% in chlorinated and ozonated tap water, ozonated mineral water, and sea water. The method was sensitive, reproducible and simple enough to permit reliable analysis of bromate to the ng/L level in water. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. A simple gas chromatography-mass spectrometry procedure for the simultaneous determination of buprenorphine and norbuprenorphine in human urine.

    PubMed

    Fuller, Dwain C

    2008-10-01

    With the increasing use of buprenorphine in treatment of opiate addiction and pain management, it is important that laboratories be able to assess patient compliance. The presented procedure is simple, efficient, and employs gas chromatography-mass spectrometry (GC-MS) technology available to most laboratories. The specimen is hydrolyzed with beta-glucuronidase prior to liquid-liquid extraction at a basic pH. The evaporated extract is derivatized to form the tertiary-butyl-dimethyl-silyl derivatives of buprenorphine and norbuprenorphine prior to analysis by GC-MS in the electron impact mode. Confirmation of the analytes is based on comparing the ion abundance ratios of the analytes to those of a contemporaneously analyzed standard. The qualitative ion abundance ratios are required to be within 20% of those of the standard for acceptance. Quantification is based on the ion ratios of the analytes to those of their corresponding deuterated analogues. Linearity was obtained for buprenorphine in the range of 1 to 2000 microg/L with a correlation coefficient (R) exceeding 0.999 and for norbuprenorphine from 1 to 1000 microg/L with R exceeding 0.997. Percent recoveries for the buprenorphine and norbuprenorphine were 71% and 75%, respectively. It was found that the recovery of norbuprenorphine could be enhanced to 100% by a simple "salting-out" modification to the procedure.

  18. Determination of microcontaminants in sediments by on-line solid-phase extraction-gas chromatography-mass spectrometry.

    PubMed

    Slobodník, J; Ramalho, S; van Baar, B L; Louter, A J; Brinkman, U A

    2000-11-01

    Two simple and straightforward analytical procedures for the screening of sediment samples are reported. They involve extraction with ethyl acetate or methanol and subsequent analysis by means of gas chromatography-mass spectrometry (GC-MS) using large-volume injection (LVI) or solid-phase extraction (SPE). The latter, which was originally developed for the analysis of aqueous samples, can be used without any modification. In general, 10 ml of organic solvent were added to 2 g of sediment, and the mixture was shaken and allowed to stand overnight. The methanolic extracts were then diluted in water and subjected to preconcentration and analysis using on-line SPE-GC-MS. The ethyl acetate extracts were injected directly into the GC using LVI. Both methods were used for the detection and identification of microcontaminants during a monitoring study of the river Nitra (Slovak Republic). They included polyaromatic hydrocarbons (PAHs), chlorofluorohydrocarbons, alkoxylated and alkylated phenols and benzothiazole derivatives. Semi-quantitative profiles of the contaminants were constructed and provisionally interpreted. The results indicate that SPE-GC-MS, and also LVI-GC-MS, have good potential for a rapid screening of sediment samples and the identification of microcontaminants. The analytical procedures pose no problems, and the on-line set-up is user-friendly.

  19. Evaluation of beer deterioration by gas chromatography-mass spectrometry/multivariate analysis: a rapid tool for assessing beer composition.

    PubMed

    Rodrigues, João A; Barros, António S; Carvalho, Beatriz; Brandão, Tiago; Gil, Ana M; Ferreira, António C Silva

    2011-02-18

    Beer stability is a major concern for the brewing industry, as beer characteristics may be subject to significant changes during storage. This paper describes a novel non-targeted methodology for monitoring the chemical changes occurring in a lager beer exposed to accelerated aging (induced by thermal treatment: 18 days at 45 °C), using gas chromatography-mass spectrometry in tandem with multivariate analysis (GC-MS/MVA). Optimization of the chromatographic run was performed, achieving a threefold reduction of the chromatographic time. Although losing optimum resolution, rapid GC runs showed similar chromatographic profiles and semi-quantitative ability to characterize volatile compounds. To evaluate the variations on the global volatile signature (chromatographic profile and m/z pattern of fragmentation in each scan) of beer during thermal deterioration, a non-supervised multivariate analysis method, Principal Component Analysis (PCA), was applied to the GC-MS data. This methodology allowed not only the rapid identification of the degree of deterioration affecting beer, but also the identification of specific compounds of relevance to the thermal deterioration process of beer, both well established markers such as 5-hydroxymethylfufural (5-HMF), furfural and diethyl succinate, as well as other compounds, to our knowledge, newly correlated to beer aging. Copyright © 2010 Elsevier B.V. All rights reserved.

  20. Gas chromatography-mass spectrometry analysis of different organic crude extracts from the local medicinal plant of Thymus vulgaris L

    PubMed Central

    Hashmi, Laila Salim Al; Hossain, Mohammad Amzad; Weli, Afaf Mohammed; Al-Riyami, Qasim; Al-Sabahi, Jamal Nasser

    2013-01-01

    Objective To isolate and analyze the chemical composition in different crude extracts of from the leaves of locally grown of Thymus vulgaris L (T. vulgaris) by gas chromatography-mass spectrometry (GC-MS). Methods The shade dried leaves powder was extracted with methanol by using Soxhlet extractor. Methanol crude extracts of T. vulgaris and the derived fractions of hexane, chloroform, ethyl acetate and butanol were obtained. Results Qualitative analyses of various organic crude extracts of T. vulgaris by using GC-MS showed that there were different types of high and low molecular weight compounds. Most of the isolated and identified compounds by GC-MS in the crude extracts are basically biologically important. Further, the T. vulgaris leaf possessed certain characteristics that can be ascribed to cultivation on a domestic plantation. The crude extracts were prepared from the powder leaves of T. vulgaris for respective compounds can be chosen on the basis of above GC-MS analysis. Conclusions All the major compounds were identified and characterized by spectroscopic method in different organic crude extracts of T. vulgaris are biologically active molecules. Thus the identification of a good number of compounds in various crude extracts of T. vulgaris might have some ecological role. PMID:23570020

  1. High Sensitivity Quantitative Lipidomics Analysis of Fatty Acids in Biological Samples by Gas Chromatography-Mass Spectrometry

    PubMed Central

    Quehenberger, Oswald; Armando, Aaron M.; Dennis, Edward A.

    2011-01-01

    Historically considered to be simple membrane components serving as structural elements and energy storing entities, fatty acids are now increasingly recognized as potent signaling molecules involved in many metabolic processes. Quantitative determination of fatty acids and exploration of fatty acid profiles have become common place in lipid analysis. We present here a reliable and sensitive method for comprehensive analysis of free fatty acids and fatty acid composition of complex lipids in biological material. The separation and quantitation of fatty acids is achieved by capillary gas chromatography. The analytical method uses pentafluorobenzyl bromide derivatization and negative chemical ionization gas chromatography-mass spectrometry. The chromatographic procedure provides base line separation between saturated and unsaturated fatty acids of different chain lengths as well as between most positional isomers. Fatty acids are extracted in the presence of isotope-labeled internal standards for high quantitation accuracy. Mass spectrometer conditions are optimized for broad detection capacity and sensitivity capable of measuring trace amounts of fatty acids in complex biological samples. PMID:21787881

  2. Identification and quantitation of urinary dicarboxylic acids as their dicyclohexyl esters in disease states by gas chromatography mass spectrometry.

    PubMed

    Norman, E J; Berry, H K; Denton, M D

    1979-12-01

    Clinical studies were conducted by gas chromatography mass spectrometry selected ion monitoring of urinary dicarboxylic acids as dicyclohexyl esters. The dicyclohexyl esters of the dicarboxylic acids give characteristic electron impact mass spectra suitable for selected ion monitoring. The mass spectra exhibit a prominent acid + 1H ion and an (acid + 1H)-H2O ion for use as quantitating and confirming ions. The cyclohexyl esters are stable for days at room temperature and have excellent chromatographic properties. Dicarboxylic acid quantitation is performed within one hour using only 50 microliter of unpurified urine. A rapid method specifically for methylmalonic acid quantitation is described which has assisted physicians in the diagnosis of pernicious anemia and methylmalonic aciduria. This procedure is applicable for screening urinary organic acids for detection of inborn errors of metabolism. The detection of a child with elevated medium length dicarboxylic acids in the terminal urine specimen is reported. This condition, previously described as an inborn error, is attributed to a terminal event. Finally, an increase in urinary succinic acid paralleling putrescine levels is described during a response to cancer chemotherapy.

  3. Determination of Drugs of Abuse in a Single Sample of Human Teeth by a Gas Chromatography-Mass Spectrometry Method.

    PubMed

    Ottaviani, Giovanni; Cameriere, Roberto; Cippitelli, Marta; Froldi, Rino; Tassoni, Giovanna; Zampi, Massimiliano; Cingolani, Mariano

    2017-01-01

    The purpose of this study was to develop and validate a gas chromatography-mass spectrometry method to detect drugs of abuse in a single sample of tooth. Pulverized samples of dental materials were subjected to acid hydrolysis to detect opiates, cocaine and their metabolites. The residual dental materials from these analyses were subjected to basic extraction to detect cannabis products (Δ(9)-tetrahydrocannabinol, cannabidiol and cannabinol). The method showed a good linearity between 0.05 and 2 ng/mg for all substances. The limit of detection ranged from 0.02 to 0.03 ng/mg, and the limit of quantification was 0.05 ng/mg. The application of the method to samples of teeth obtained from drug addicts was successful. It can be applied in post-mortem cases, especially when limited amounts of sample are available. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  4. Development of a functional assay to detect inhibitors of Plasmodium falciparum glutathione reductase utilizing liquid chromatography-mass spectrometry.

    PubMed

    Burkard, Lexi; Scheuermann, Alexis; Simithy, Johayra; Calderón, Angela I

    2016-04-01

    Plasmodium falciparum (Pf) like most other organisms, has a sophisticated antioxidant system, part of which includes glutathione reductase (GR). GR works by recycling toxic glutathione disulfide to glutathione, thereby reducing reactive oxygen species and making a form of glutathione (GSH) the parasite can use. Inhibition of this enzyme in Pf impedes parasite growth. In addition, it has been confirmed that PfGR is not identical to human GR. Thus, PfGR is an excellent target for antimalarial drug development. A functional assay utilizing liquid chromatography-mass spectrometry was developed to specifically identify and evaluate inhibitors of PfGR. Using recombinant PfGR enzyme and 1,4-naphthoquinone (1) as a reference compound and 4-nitrobenzothiadiazole (2) and methylene blue (3) as additional compounds, we quantified the concentration of GSH produced compared with a control to determine the inhibitory effect of these compounds. Our results coincide with that presented in literature: compounds 1-3 inhibit PfGR with IC50 values of 2.71, 8.38, and 19.23 µm, respectively. Good precision for this assay was exhibited by low values of intraday and interday coefficient of variation (3.1 and 2.4%, respectively). Thus, this assay can be used to screen for other potential inhibitors of PfGR quickly and accurately.

  5. Fluoroacetylation/fluoroethylesterification as a derivatization approach for gas chromatography-mass spectrometry in metabolomics: preliminary study of lymphohyperplastic diseases.

    PubMed

    Karamani, Anna A; Fiamegos, Yiannis Ch; Vartholomatos, George; Stalikas, Constantine D

    2013-08-09

    Metabolic fingerprinting in combination with gas chromatography and multivariate analysis is being extensively employed for the improved understanding of biological changes induced by endogenous or exogenous factors. Chemical derivatization increases the sensitivity and specificity of gas chromatography-mass spectrometry (GC-MS) for polar or thermally labile biological compounds, which bear derivatizable groups. Thus, there is a constant demand for simple methods of derivatization and separation that satisfy the need for metabolite analysis, identifying as many chemical classes of compounds as possible. In this study, an optimized protocol of extraction and derivatization is established as a generally applicable method for the analysis of a wide range of classes of metabolites in urine, whole blood and saliva. Compounds of biological relevance bearing hydroxyl- carboxyl- and amino-groups are derivatized using single-step fluoroacetylation/fluoroethylesterification after proper optimization of the protocol. Subsequently, the developed derivatization procedure is engaged in finding blood metabolic biomarkers, induced by lymphohyperplastic disease, through the metabolomic fingerprinting approach, the multivariate modeling (hierarchical cluster analysis) and GC-MS. Our preliminary, GC-MS-based metabolomic fingerprinting study underlines the contribution of certain metabolites to the discrimination of patients with lymphohyperplastic diseases.

  6. Recent trends in application of multivariate curve resolution approaches for improving gas chromatography-mass spectrometry analysis of essential oils.

    PubMed

    Jalali-Heravi, Mehdi; Parastar, Hadi

    2011-08-15

    Essential oils (EOs) are valuable natural products that are popular nowadays in the world due to their effects on the health conditions of human beings and their role in preventing and curing diseases. In addition, EOs have a broad range of applications in foods, perfumes, cosmetics and human nutrition. Among different techniques for analysis of EOs, gas chromatography-mass spectrometry (GC-MS) is the most important one in recent years. However, there are some fundamental problems in GC-MS analysis including baseline drift, spectral background, noise, low S/N (signal to noise) ratio, changes in the peak shapes and co-elution. Multivariate curve resolution (MCR) approaches cope with ongoing challenges and are able to handle these problems. This review focuses on the application of MCR techniques for improving GC-MS analysis of EOs published between January 2000 and December 2010. In the first part, the importance of EOs in human life and their relevance in analytical chemistry is discussed. In the second part, an insight into some basics needed to understand prospects and limitations of the MCR techniques are given. In the third part, the significance of the combination of the MCR approaches with GC-MS analysis of EOs is highlighted. Furthermore, the commonly used algorithms for preprocessing, chemical rank determination, local rank analysis and multivariate resolution in the field of EOs analysis are reviewed.

  7. Gas chromatography-mass spectrometry screening for phytochemical 4-desmethylsterols accumulated during development of Tunisian peanut kernels (Arachis hypogaea L.).

    PubMed

    Cherif, Aicha O; Trabelsi, Hajer; Ben Messaouda, Mhamed; Kâabi, Belhassen; Pellerin, Isabelle; Boukhchina, Sadok; Kallel, Habib; Pepe, Claude

    2010-08-11

    4-Desmethylsterols, the main component of the phytosterol fraction, have been analyzed during the development of Tunisian peanut kernels ( Arachis hypogaea L.), Trabelsia (AraT) and Chounfakhi (AraC), which are monocultivar species, and Arbi (AraA), which is a wild species, by gas chromatography-mass spectrometry. Immature wild peanut (AraA) showed the highest contents of beta-sitosterol (554.8 mg/100 g of oil), campesterol (228.6 mg/100 g of oil), and Delta(5)-avenasterol (39.0 mg/100 g of oil) followed by peanut cultivar AraC with beta-sitosterol, campesterol, and Delta(5)-avenasterol averages of 267.7, 92.1, and 28.6 mg/100 g of oil, respectively, and similarly for AraT 309.1, 108.4, and 27.4 mg/100 g of oil, respectively, were found. These results suggest that, in immature stages, phytosterol contents can be important regulator factors for the functional quality of peanut oil for the agro-industry chain from plant to nutraceuticals.

  8. Determination of carbon number distributions of complex phthalates by gas chromatography-mass spectrometry with ammonia chemical ionization.

    PubMed

    Di Sanzo, Frank P; Lim, Peniel J; Han, Wenning W

    2015-01-01

    An assay method for phthalate esters with a complex mixture of isomer of varying carbon numbers, such as di-isononyl phthalate (DINP) and di-isodecyl phthalate (DIDP), using gas chromatography-mass spectrometry (GC-MS) positive chemical ionization (PCI) with 5% ammonia in methane is described. GC-MS-PCI-NH3, unlike GC-MS electron ionization (EI) (GC-MS-EI) that produces generally m/z 149 ion as the main base peak and low intensity M(+) peaks, produces higher intensity (M + 1) ions that allow the determination of total (R + R') carbon number distributions based on the various R and R' alkyl groups of the di-esters moiety. The technique allows distinguishing among the various commercial DINP and DIDP plasticizers. The carbon number distributions are determined in the acceptable range of <0.1 mole percent to >85 mole percent (m/m). Several examples of analysis made on commercial DINP and DIDP are presented. The use of only 5% instead of 100% ammonia simplifies use of GC-MS-PCI-NH3 but still produces sufficient M + 1 ion intensities that are appropriate for the assay. In addition, use of low concentrations of ammonia mitigates potential safety aspects related to use of ammonia and provides less corrosion for the instrument hardware.

  9. Metal free columns for determination of deoxynucleotide monophosphate by liquid chromatography/mass spectrometry and application to oligonucleotide.

    PubMed

    Shibayama, Sachie; Sakamaki, Hiroshi; Yamazaki, Taichi; Takatsu, Akiko

    2015-08-07

    We have developed a highly sensitive method for the analysis of deoxynucleotide monophosphates (dNMPs), which involves the use of liquid chromatography/mass spectrometry (LC/MS) and a new metal-free column. The new column solves the problem that the phosphate group in dNMPs interacts with the metal portion of the device or column. After optimization of the analytical conditions, the limits of detection (LODs) of dNMPs were from 5.4ng/g to 6.3ng/g. Those values were 10 times lower than the LODs of previous methods. We applied the method to the determination of the base composition and the quantification of 20-mer oligonucleotide. Despite use of a very small sample amount of 14.5ng, we were able to determine the base composition, and the result was consistent with theoretical values. We were also able to quantify the mass fraction of oligonucleotide with 8.2% expanded uncertainty (k=2). By means of the developed method, we were able to analyze dNMPs with high sensitivity as well as determine the base composition and quantify the mass fraction of oligonucleotide despite use of a small amount of sample. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Determination of cocaine and heroin with their respective metabolites in meconium by gas chromatography-mass spectrometry.

    PubMed

    López, P; Bermejo, A M; Tabernero, M J; Fernández, P; Alvarez, I

    2007-01-01

    The analysis of meconium specimens is a relatively accurate method for the detection of fetal exposure to drugs. The purpose of this study was to develop and validate a method for meconium sample preparation for a gas chromatography-mass spectrometry (GC-MS) confirmation of meconium extracts for cocaine, benzoylecgonine, codeine, morphine and 6-monoacetylmorphine. The analytes were initially extracted from the matrix by methanol. Subsequently a solid-phase extraction with Waters Oasis HLB cartridges was applied. Analytes were determined in GC-MS single monitoring mode. The method was validated in the range 40-2000 ng g(-1) using 0.5 g of meconium per assay. The detector response was linear over the studied range, and limits of quantitation and detection were found to be acceptable. Intra- and inter-batch coefficients of variation oscillated between 2.54% and 20.5%, and mean relative errors were in the range 0.79%-19.9%. The recoveries were higher than 42.1% in all cases. Finally the method was applied to analysis of meconium in newborns to assess fetal exposure to cocaine and opiates.

  11. Simultaneous determination of cyanide and thiocyanate in plasma by chemical ionization gas chromatography mass-spectrometry (CI-GC-MS).

    PubMed

    Bhandari, Raj K; Oda, Robert P; Youso, Stephanie L; Petrikovics, Ilona; Bebarta, Vikhyat S; Rockwood, Gary A; Logue, Brian A

    2012-11-01

    An analytical method utilizing chemical ionization gas chromatography-mass spectrometry was developed for the simultaneous determination of cyanide and thiocyanate in plasma. Sample preparation for this analysis required essentially one-step by combining the reaction of cyanide and thiocyanate with pentafluorobenzyl bromide and simultaneous extraction of the product into ethyl acetate facilitated by a phase-transfer catalyst, tetrabutylammonium sulfate. The limits of detection for cyanide and thiocyanate were 1 μM and 50 nM, respectively. The linear dynamic range was from 10 μM to 20 mM for cyanide and from 500 nM to 200 μM for thiocyanate with correlation coefficients higher than 0.999 for both cyanide and thiocyanate. The precision, as measured by %RSD, was below 9 %, and the accuracy was within 15 % of the nominal concentration for all quality control standards analyzed. The gross recoveries of cyanide and thiocyanate from plasma were over 90 %. Using this method, the toxicokinetic behavior of cyanide and thiocyanate in swine plasma was assessed following cyanide exposure.

  12. Determination of aromatic hydrocarbons in bituminous emulsion sealants using headspace solid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Tang, Bing; Isacsson, Ulf

    2006-12-22

    The possibility of quantitative determination of aromatic hydrocarbons in bituminous emulsion sealants was investigated using headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS). The target analytes studied were benzene, toluene, ethylbenzene, p-, m-, and o-xylene (BTEX) as well as 1,3,5- and 1,2,4-trimethylbenzene. Experimental factors influencing HS-SPME efficiency were studied (sample-headspace equilibration time, extraction time and sample matrix effects). A HS-SPME method using surrogate matrix was developed. The detection limit was estimated as approximately 0.1 ppmw for the target analytes investigated. Good linearity was observed (R(2)>0.997) for all calibration curves obtained. The repeatability of the method (RSD, relative standard deviation) was found less than 10%. The accuracy of the method given by recovery of spiked samples was between 99 and 116%. The HS-SPME method developed was applied to two commercially available bituminous emulsion sealants. External calibration and standard addition approaches were investigated, and statistical paired t-test was performed. The contents of target aromatic hydrocarbons in the sealants studied varied from approximately 0.4 to 150 ppmw. The method developed shows potential as a tool for the determination of aromatic hydrocarbons in emulsified bituminous materials.

  13. [Determination of apomorphine, sildenafil and alprostadil in medicines for erectile dysfunction by high performance liquid chromatography-mass spectrometry].

    PubMed

    Xu, Yuanjin; Xu, Guiping

    2005-11-01

    A high performance liquid chromatography-mass spectrometry (LC-MS) analytical method for illicit drugs, apomorphine, sildenafil and alprostadil, in medicines for erectile dysfunction has been developed. The samples were extracted with methanol using ultrasound-assisted extraction. The chromatographic separation was performed on a Zorbax Eclipse XDB-C18 column using acetonitrile-0.5% formic acid aqueous solution as mobile phase. The three compounds were identified by retention time and m/z and quantified by peak area. The results demonstrated that the linear ranges were 50.0 - 5 000.0 microg/L, 10.0 - 1 000.0 microg/L, 40.0 - 4 000.0 microg/L, with detection limits of 20.0, 4.0, 10.0 microg/L for apomorphine, sildenafil and alprostadil, respectively. The average recoveries and the relative standard deviations were 89% - 95% and 9.5% - 11%. The method is simple, rapid, accurate and suitable for the simultaneous determination of these drugs in medicines for erectile dysfunction.

  14. Identification the Key Odorants in Different Parts of Hyla Rabbit Meat via Solid Phase Microextraction Using Gas Chromatography Mass Spectrometry

    PubMed Central

    Lv, Jingzhi; Zhang, En

    2016-01-01

    The aim of this study was to explore the volatile compounds of hind leg, foreleg, abdomen and Longissimus dorsi in both male and female Hyla rabbit meat by solid phase microextraction tandem with gas chromatography mass spectrometry, and to seek out the key odorants via calculating the odor activity value and principal component analysis. Cluster analysis is used to study the flavor pattern differences in four edible parts. Sixty three volatile compounds were detected, including 23 aldehydes, 4 alcohols, 5 ketones, 11 esters, 5 aromatics, 8 acids and 7 hydrocarbons. Among them, 6 aldehydes and 3 acids were identified as the potential key odorants according to the ratio of concentration and threshold. The contents of volatile compounds in male Hyla rabbit meat were significantly higher than those in female one (p<0.05). The results of principal component analysis showed that the first two principal component cumulative variance contributions reach 87.69%; Hexanal, octanal, 2-nonenal, 2-decenal and decanal were regard as the key odorants of Hyla rabbit meat by combining odor activity value and principal component analysis. Therefore volatile compounds of rabbit meat can be effectively characterized. Cluster analysis indicated that volatile chemical compounds of Longissimus dorsi were significantly different from other three parts, which provide reliable information for rabbit processing industry and for possible future sale. PMID:28115882

  15. Distinguishing chinese star anise from Japanese star anise using thermal desorption-gas chromatography-mass spectrometry.

    PubMed

    Howes, Melanie-Jayne R; Kite, Geoffrey C; Simmonds, Monique S J

    2009-07-08

    The volatile compounds from the pericarps of Illicium anisatum L., Illicium brevistylum A.C.Sm., Illicium griffithii Hook.f. & Thomson, Illicium henryi Diels, Illicium lanceolatum A.C.Sm., Illicium majus Hook.f. & Thomson, Illicium micranthum Dunn, and Illicium verum Hook.f. were examined by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). The volatiles desorbed from the pericarps of I. verum (Chinese star anise), the species traded for culinary purposes, were generally characterized by a high proportion of (E)-anethole (57.6-77.1%) and the presence of foeniculin; the latter was otherwise only detected in the pericarps of I. lanceolatum. In the pericarps of all other species analyzed, the percentage composition of (E)-anethole was comparatively lower (

  16. Characterization of organic fouling in reverse osmosis membranes by headspace solid phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Martínez, C; Gómez, V; Pocurull, E; Borrull, F

    2015-01-01

    Adsorption of organic substances on reverse osmosis (RO) membrane surfaces may form an organic film on the membrane, known as organic fouling, and cause flow-rate loss. This problem is mostly unavoidable as no pretreatment method exists for perfect removal of possible foulants, including organic compounds resulting from undesirable bioactivity. Understanding the characteristics of fouling layers is an essential step towards overall improvement of RO membrane operations. In this study, the organic fouling in RO membranes treating the effluent of a secondary treatment from an urban wastewater treatment plant was characterized. Headspace solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry has been used for the first time, to provide valuable information of organic fouling. Different polarity SPME fibers were tested for this purpose. In addition, the characterization of the organic fouling obtained by HS-SPME was compared with the results obtained by extraction using several organic solvents. The results indicated that more compound families can be identified by HS-SPME than by organic solvent extraction. Moreover, complementary organic analyses were done for better understanding of the organic fouling in RO membranes, such as total organic carbon and loss on ignition.

  17. Determination of dimethyl trisulfide in rabbit blood using stir bar sorptive extraction gas chromatography-mass spectrometry.

    PubMed

    Manandhar, Erica; Maslamani, Nujud; Petrikovics, Ilona; Rockwood, Gary A; Logue, Brian A

    2016-08-26

    Cyanide poisoning by accidental or intentional exposure poses a severe health risk. The current Food and Drug Administration approved antidotes for cyanide poisoning can be effective, but each suffers from specific major limitations concerning large effective dosage, delayed onset of action, or dependence on enzymes generally confined to specific organs. Dimethyl trisulfide (DMTS), a sulfur donor that detoxifies cyanide by converting it into thiocyanate (a relatively nontoxic cyanide metabolite), is a promising next generation cyanide antidote. Although a validated analytical method to analyze DMTS from any matrix is not currently available, one will be vital for the approval of DMTS as a therapeutic agent against cyanide poisoning. Hence, a stir bar sorptive extraction (SBSE) gas chromatography - mass spectrometry (GC-MS) method was developed and validated for the analysis of DMTS from rabbit whole blood. Following acid denaturation of blood, DMTS was extracted into a polydimethylsiloxane-coated stir bar. The DMTS was then thermally desorbed from the stir bar and analyzed by GC-MS. The limit of detection of DMTS using this method was 0.06μM with dynamic range from 0.5-100μM. For quality control standards, the precision, as measured by percent relative standard deviation, was below 10%, and the accuracy was within 15% of the nominal concentration. The method described here will allow further investigations of DMTS as a promising antidote for cyanide poisoning.

  18. Liquid Chromatography Mass Spectrometry-Based Metabolite Pathway Analyses of Myeloma and Non-Hodgkin’s Lymphoma Patients

    PubMed Central

    Medriano, Carl Angelo D.; Na, Jinhyuk; Lim, Kyung-min; Chung, Jin-ho; Park, Youngja H.

    2017-01-01

    Objective This study attempted to identify altered metabolism and pathways related to non-Hodgkin’s lymphoma (NHL) and myeloma patients. Materials and Methods In this retrospective study, we collected plasma samples from 11 patients-6 healthy controls with no evidence of any blood cancers and 5 patients with either multiple myeloma (n=3) or NHL (n=2) during the preliminary study period. Samples were analyzed using quadrupole time-of-flight liquid chromatography mass spectrometry (LC-MS). Significant features generated after statistical analyses were used for metabolomics and pathway analysis. Results Data after false discovery rate (FDR) adjustment at q=0.05 of features showed 136 for positive and 350 significant features for negative ionization mode in NHL patients as well as 262 for positive and 98 features for negative ionization mode in myeloma patients. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis determined that pathways such as steroid hormone biosynthesis, ABC transporters, and arginine and proline metabolism were affected in NHL patients. In myeloma patients, pyrimidine metabolism, carbon metabolism, and bile secretion pathways were potentially affected by the disease. Conclusion The results have shown tremendous differences in the metabolites of healthy individuals compared to myeloma and lymphoma patients. Validation through quantitative metabolomics is encouraged, especially for the metabolites with significantly expression in blood cancer patients. PMID:28580307

  19. Linear and cyclic methylsiloxanes in air by concurrent solvent recondensation-large volume injection-gas chromatography-mass spectrometry.

    PubMed

    Companioni-Damas, E Y; Santos, F J; Galceran, M T

    2014-01-01

    In the present work, a simple and fast method for the analysis of linear and cyclic methylsiloxanes in ambient air based on active sampling combined with gas chromatography - mass spectrometry (GC-MS) was developed. The retention efficiency of five sampling sorbents (activated coconut charcoal, Carbopack B, Cromosorb 102, Cromosorb 106 and Isolute ENV+) was evaluated and Isolute ENV+ was found to be the most effective. A volume of 2700 L of air can be sampled without significant losses of the most volatile methylsiloxanes. To improve the sensitivity of the GC-MS method, concurrent solvent recondensation - large volume injection (CSR-LVI), using volumes up to 30 µl of sample extract, is proposed and limits of quantification down to 0.03-0.45 ng m(-3), good linearity (r>0.999) and precision (RSD %<9%) were obtained. The developed method was applied to the analysis of ambient air. Concentrations of linear and cyclic methylsiloxanes in indoor air ranging from 3.9 to 319 ng m(-3) and between 48 and 292668 ng m(-3), were obtained, respectively, while levels from 6 to 22 ng m(-3) for linear and between 2.2 and 439 ng m(-3) for cyclic methylsiloxanes in outdoor air from Barcelona (Spain), were found.

  20. Determination of petroleum hydrocarbons in contaminated soils using solid-phase microextraction with gas chromatography-mass spectrometry.

    PubMed

    Cam, D; Gagni, S

    2001-11-01

    Manual solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry is investigated as a possible alternative for the determination of petroleum hydrocarbons in soils. Spiked onto an agricultural soil is a commercial diesel fuel (DF) with the following composition by weight: 12% linear alkanes, 52% saturated hydrocarbons (branched and cyclic), 21% alkylated aromatic hydrocarbons, 6% polycyclic aromatic hydrocarbons, and 9% unidentified compounds. The spiked soil samples are aged three days at room temperature before analysis. The optimal conditions for the SPME of DF from soils are examined and maximum sensitivity is obtained using a 100-microm polydimethylsiloxane fiber at a sampling temperature of 47 degrees C by sonication both in the headspace and directly through a water medium. The reproducibility of the whole technique showed a relative standard deviation of 10%. The parameters that can influence the recovery of DF (such as the time of SPME extraction, the presence of organic solvent and water, and the matrix) are investigated. The linearity is verified in the range of 40 to 1200 mg/L for the direct injection of DF, 0.1 to 1 mg/L for the SPME of DF from water, and 1 to 50 mg/Kg of dry soil for the SPME of DF from soils. The detection limits are respectively 0.5 mg/L, 0.02 mg/L, and 0.1 mg/Kg of dry soil. The method is corroborated by comparing the results with those obtained by the traditional way.

  1. [Determination of bisphenol A from toys and food contact materials by derivatization and gas chromatography-mass spectrometry].

    PubMed

    Gao, Yonggang; Zhang, Yanyan; Gao, Jianguo; Zhang, Huiling; Zheng, Lisha; Chen, Jing

    2012-10-01

    A method was developed for the determination of bisphenol A (BPA) in toys and food contact materials. The BPA was extracted with Soxhlet extraction method from the sample and reacted with acetic anhydride. The final product was determined by gas chromatography-mass spectrometry (GC-MS). To achieve the optimum derivatization performance, the derivatization time and dosage of derivatization reagent etc. were investigated. Under the optimized experimental conditions, the final product was stable and the peak shape was good. The linearity of the derivative was good in the range of 0.05 to 50 mg/L with the correlation coefficient (r2) above 0.999. The recoveries ranged from 80% to 93% at the spiked levels of 0.05, 1.00, 10.00 mg/kg with the relative standard deviations (RSDs) less than 3.7%. The limit of detection (S/N = 3) was 10 microg/kg. The method is accurate and has high recovery. The method is suitable for the inspection of bisphenol A in toys and food contact materials.

  2. Liquid chromatography-fluorescence and liquid chromatography-mass spectrometry detection of tryptophan degradation products of a recombinant monoclonal antibody.

    PubMed

    Nowak, Christine; Ponniah, Gomathinayagam; Cheng, Guilong; Kita, Adriana; Neill, Alyssa; Kori, Yekaterina; Liu, Hongcheng

    2016-03-01

    Light exposure is one of several conditions used to study the degradation pathways of recombinant monoclonal antibodies. Tryptophan is of particular interest among the 20 amino acids because it is the most photosensitive. Tryptophan degradation forms several products, including an even stronger photosensitizer and several reactive oxygen species. The current study reports a specific peptide mapping procedure to monitor tryptophan degradation. Instead of monitoring peptides using UV 214 nm, fluorescence detection with an excitation wavelength of 295 nm and an emission wavelength of 350 nm was used to enable specific detection of tryptophan-containing peptides. Peaks that decreased in area over time are likely to contain susceptible tryptophan residues. This observation can allow further liquid chromatography-mass spectrometry (LC-MS) analysis to focus only on those peaks to confirm tryptophan degradation products. After confirmation of tryptophan degradation, susceptibility of tryptophan residues can be compared based on the peak area decrease. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Serum creatinine determined by Jaffe, enzymatic method, and isotope dilution-liquid chromatography-mass spectrometry in patients under hemodialysis.

    PubMed

    Liu, Wen-Sheng; Chung, Yu-Ting; Yang, Chih-Yu; Lin, Chih-Ching; Tsai, Kun-Hung; Yang, Wu-Chang; Chen, Tzen-Wen; Lai, Yen-Ting; Li, Szu-Yuan; Liu, Tsung-Yun

    2012-05-01

    Serum creatinine is an important clinical marker for renal clearance. However, the Jaffe method had much interference and the accuracy had not been tested in patients under hemodialysis (HD) with standard isotope dilution-liquid chromatography-mass spectrometry (IDLCMS) method. The validity of enzymatic method is also unknown. The predialysis serum creatinine levels of 126 patients under regular HD for 3 months were checked by Jaffe, enzymatic, and IDLCMS methods. We compared the value of the Jaffe and enzymatic to that of IDLCMS in linear regression model. And we also tried to find the clinical parameters that influence the difference between Jaffe vs. IDLCMS and enzymatic vs. IDLCMS method. We found significant underestimate serum creatinine in uremic patients by Jaffe and enzymatic methods. Serum glucose and globulin are positive biases, whereas albumin, potassium, and phosphorus are negative biases. Enzymatic method is less affected by serum glucose and serum protein. Albumin acts differently in uremic serum compared to the results of mixing them with normal serum. For uremic patients, in whom creatinine level is high and many of them suffered from diabetes mellitus, serum creatinine can be either under- or overestimated by Jaffe method. Enzymatic method is less affected and may be a better method. © 2012 Wiley Periodicals, Inc.

  4. A hydrophilic interaction liquid chromatography-mass spectrometry (HILIC-MS) based metabolomics study on colour stability of ovine meat.

    PubMed

    Subbaraj, Arvind K; Kim, Yuan H Brad; Fraser, Karl; Farouk, Mustafa M

    2016-07-01

    Meat colour is one of the cues available to the consumer to gauge overall meat quality and wholesomeness. Colour stability of meat is determined by several factors both inherent to the animal and post-slaughter conditions, including ageing, storage/packaging and display times. A hydrophilic interaction liquid chromatography-mass spectrometry (HILIC-MS) based metabolomics study was undertaken to identify and compare polar metabolites between ovine meat samples that were exposed to different durations of ageing, storage conditions, and display times. Primary metabolites comprising amino acids, sugars, nucleotides, nucleosides, organic acids and their breakdown products were mainly identified as discriminating factors. For the first time, boron complexes of sugar and malic acid were also tentatively identified. As expected, most compounds identified were related to myoglobin chemistry, and compounds with antioxidant properties were found in higher levels in colour stable samples. Supplementary studies identifying semi-polar, non-polar and volatile compounds will provide a holistic understanding of the chemical basis of colour stability in ovine meat.

  5. Derivatization procedures and determination of levoglucosan and related monosaccharide anhydrides in atmospheric aerosols by gas chromatography-mass spectrometry.

    PubMed

    Hsu, Ching-Lin; Cheng, Chin-Yuan; Lee, Chung-Te; Ding, Wang-Hsien

    2007-04-15

    This study evaluated the derivatization procedures for detecting the three most commonly monosaccharide anhydrides (MAs) (levoglucosan, mannosan and galactosan) in atmospheric aerosols using gas chromatography-mass spectrometry (GC-MS). Various silylating agents, mainly trimethylsilylating agents (TMS), were compared and the effects of various contents of trimethylchlorosilane (TMCS, as a stimulator) were evaluated to optimize the conditions for detecting these compounds in aerosol samples. Differences among the abundances of the derivatives were caused by the sterical hindrance of three hydroxyl groups in the structures of monosaccharide anhydrides. The effects of the reaction time and temperature were also examined. The optimal reaction time and temperature were 60min and 80 degrees C with 1% TMCS plus 0.2% 1,4-dithioerythritol (DTE). Under these conditions, the percentages of formation of bis-O-TMS derivatives (as by-products) were 23, 29 and 10% for galactosan, mannosan and levoglucosan, respectively. The concentrations of galactosan, mannosan and levoglucosan in particles of smoke samples ranged from 29 to 88, 23 to 69 and 77 to 380ng/m(3), respectively; and in particles of atmospheric aerosols ranged from 0.06 to 0.75, n.d. to 0.49 and 1.6 to 132ng/m(3), respectively. Levoglucosan was the dominant MAs detected in both type of samples. Less than 10% quantitation difference was obtained when bis-O-TMS derivatives were included in the calculation.

  6. MSPD procedure for determining buprofezin, tetradifon, vinclozolin, and bifenthrin residues in propolis by gas chromatography-mass spectrometry.

    PubMed

    dos Santos, Thaíse Fernanda Santana; Aquino, Adriano; Dórea, Haroldo Silveira; Navickiene, Sandro

    2008-03-01

    A simple and effective extraction method based on matrix solid-phase dispersion (MSPD) was developed to determine bifenthrin, buprofezin, tetradifon, and vinclozolin in propolis using gas chromatography-mass spectrometry in selected ion monitoring mode (GC-MS, SIM). Different method conditions were evaluated, for example type of solid phase (C(18), alumina, silica, and Florisil), the amount of solid phase and eluent (n-hexane, dichloromethane, dichloromethane-n-hexane (8:2 and 1:1, v/v) and dichloromethane-ethyl acetate (9:1, 8:2 and 7:3, v/v)). The best results were obtained using 0.5 g propolis, 1.0 g silica as dispersant sorbent, 1.0 g Florisil as clean-up sorbent, and dichloromethane-ethyl acetate (9:1, v/v) as eluting solvent. The method was validated by analysis of propolis samples fortified at different concentration levels (0.25 to 1.0 mg kg(-1)). Average recoveries (four replicates) ranged from 67% to 175% with relative standard deviation between 5.6% and 12.1%. Detection and quantification limits ranged from 0.05 to 0.10 mg kg(-1) and 0.15 to 0.25 mg kg(-1) propolis, respectively.

  7. Gas Chromatography-Mass Spectrometry Analysis of Ulva fasciata (Green Seaweed) Extract and Evaluation of Its Cytoprotective and Antigenotoxic Effects

    PubMed Central

    Rodeiro, Idania; Olguín, Sitlali; Santes, Rebeca; Herrera, José A.; Pérez, Carlos L.; Mangas, Raisa; Hernández, Yasnay; Fernández, Gisselle; Hernández, Ivones; Hernández-Ojeda, Sandra; Camacho-Carranza, Rafael; Valencia-Olvera, Ana; Espinosa-Aguirre, Jesús Javier

    2015-01-01

    The chemical composition and biological properties of Ulva fasciata aqueous-ethanolic extract were examined. Five components were identified in one fraction prepared from the extract by gas chromatography-mass spectrometry, and palmitic acid and its ethyl ester accounted for 76% of the total identified components. Furthermore, we assessed the extract's antioxidant properties by using the DPPH, ABTS, and lipid peroxidation assays and found that the extract had a moderate scavenging effect. In an experiment involving preexposition and coexposition of the extract (1–500 µg/mL) and benzo[a]pyrene (BP), the extract was found to be nontoxic to C9 cells in culture and to inhibit the cytotoxicity induced by BP. As BP is biotransformed by CYP1A and CYP2B subfamilies, we explored the possible interaction of the extract with these enzymes. The extract (25–50 µg/mL) inhibited CYP1A1 activity in rat liver microsomes. Analysis of the inhibition kinetics revealed a mixed-type inhibitory effect on CYP1A1 supersome. The effects of the extract on BP-induced DNA damage and hepatic CYP activity in mice were also investigated. Micronuclei induction by BP and liver CYP1A1/2 activities significantly decreased in animals treated with the extract. The results suggest that Ulva fasciata aqueous-ethanolic extract inhibits BP bioactivation and it may be a potential chemopreventive agent. PMID:26612994

  8. Novel ethyl-derivatization approach for the determination of fluoride by headspace gas chromatography/mass spectrometry.

    PubMed

    Pagliano, Enea; Meija, Juris; Ding, Jianfu; Sturgeon, Ralph E; D'Ulivo, Alessandro; Mester, Zoltán

    2013-01-15

    We report a novel derivatization chemistry for determination of fluoride based on the batch reaction of fluoride ions with triethyloxonium tetrachloroferrate(III) in a closed vessel to yield fluoroethane. Gaseous fluoroethane was readily separated from the matrix, sampled from the headspace, and determined by gas chromatography/mass spectrometry. The method was validated using rainwater certified reference material (IRMM CA408) and subsequently applied to the determination of fluoride in various matrixes, including tap water, seawater, and urine. An instrumental limit of detection of 3.2 μg/L with a linear range up to 50 mg/L was achieved. The proposed derivatization is a one-step reaction, requires no organic solvents, and is safe, as the derivatizing agent is nonvolatile. Determination of fluoride is affected by common fluoride-complexing agents, such as Al(III) and Fe(III). The effect of large amounts of these interferences was studied, and the adverse effect of these ions was eliminated by use of the method of standard additions.

  9. Metabolic toxicity screening using electrochemiluminescence arrays coupled with enzyme-DNA biocolloid reactors and liquid chromatography-mass spectrometry.

    PubMed

    Hvastkovs, Eli G; Schenkman, John B; Rusling, James F

    2012-01-01

    New chemicals or drugs must be guaranteed safe before they can be marketed. Despite widespread use of bioassay panels for toxicity prediction, products that are toxic to a subset of the population often are not identified until clinical trials. This article reviews new array methodologies based on enzyme/DNA films that form and identify DNA-reactive metabolites that are indicators of potentially genotoxic species. This molecularly based methodology is designed in a rapid screening array that utilizes electrochemiluminescence (ECL) to detect metabolite-DNA reactions, as well as biocolloid reactors that provide the DNA adducts and metabolites for liquid chromatography-mass spectrometry (LC-MS) analysis. ECL arrays provide rapid toxicity screening, and the biocolloid reactor LC-MS approach provides a valuable follow-up on structure, identification, and formation rates of DNA adducts for toxicity hits from the ECL array screening. Specific examples using this strategy are discussed. Integration of high-throughput versions of these toxicity-screening methods with existing drug toxicity bioassays should allow for better human toxicity prediction as well as more informed decision making regarding new chemical and drug candidates.

  10. Analysis of linear and cyclic methylsiloxanes in water by headspace-solid phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Companioni-Damas, E Y; Santos, F J; Galceran, M T

    2012-01-30

    This paper proposes a new method for the analysis of linear and cyclic methylsiloxanes in water samples based on headspace-solid phase microextraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS). The extraction efficiency of four commercially available SPME-fibres was evaluated and it was found that a 65 μm polydimethylsiloxane/divinylbenzene (PDMS/DVB) coating was the most suitable for the extraction of siloxanes. The method provided good linearity (r>0.999) and precision (RSD % <17%), and low limits of quantification ranging from 0.01 to 0.74 ng L(-1) for linear siloxanes and between 18 and 34 ng L(-1) for cyclic siloxanes. The HS-SPME-GC-MS method was applied to the analysis of linear and cyclic siloxanes in river waters from Catalonia (NE, Spain) and the results showed concentrations of linear and cyclic siloxanes ranging from 0.09 to 3.94 ng L(-1) and 22.2 to 58.5 ng L(-1), respectively.

  11. Assessment of acetone as an alternative to acetonitrile in peptide analysis by liquid chromatography/mass spectrometry.

    PubMed

    Fritz, Ria; Ruth, Wolfgang; Kragl, Udo

    2009-07-01

    Acetonitrile as a solvent used in liquid chromatography/mass spectrometry (LC/MS) of peptides and proteins is a relatively toxic solvent (LD50 oral; rat; 2,460 mg/kg) compared to alternatives like methanol (LD50 oral; rat; 5,628 mg/kg) and acetone (LD50 oral; rat; 5,800 mg/kg). Strategies to minimize its consumption in LC are either to reduce the inner diameter of the column or replace acetonitrile with a suitable alternative. Methanol is often recommended to replace acetonitrile in peptide analysis. In this study however, the main focus lies on another alternative solvent for LC/MS of peptides; acetone. A number of model proteins were tryptically digested and the peptide solutions were analyzed on a linear trap quadrupole (LTQ) mass spectrometer. The performances of acetonitrile, methanol and acetone were compared according to the quality of the chromatograms obtained and identification of the peptides using the BioWorks software developed by Thermo Scientific. In accordance to the elutropic series, acetone was found to significantly reduce the retention times of peptides separated by C18 column material with regard to acetonitrile while methanol led to increased retention times. Acetone was the superior solvent to methanol for most of the tested model proteins reaching similar sequence coverage and numbers of identified peptides as acetonitrile. We therefore propose acetone as an alternative to acetonitrile in LC/MS of peptides.

  12. [Simultaneous determination of nine pharmaceuticals personal care products in waters by solid phase extraction-gas chromatography-mass spectrometry].

    PubMed

    Jia, Yanyan; Tan, Jianhua; Xu, Chen; Tang, Jiajun; Wang, Yingli; Xie, Qilai

    2014-03-01

    An analytical method has been developed and validated for the simultaneous determination of nine pharmaceuticals and personal care products (PPCPs) in water samples, including salicylic acid, naproxen, ibuprofen, paracetamol, clofibric acid, triclosan, diclofenac, ketoprofen, bisphenol A. The qualification and quantification of the target compounds were performed by gas chromatography-mass spectrometry in selected ion monitoring mode (GC-MS-SIM). The water samples were concentrated and purified through Oasis HLB cartridges after the pH value of the water was adjusted to 3, then derivatized with trimethyl sulfonium hydroxide (TMSH) at room temperature, and determined by GC-MS-SIM using 2,4,5-fenoprop as internal standard. The conditions for sample pretreatment (e. g. solid phase extraction and derivatization) were studied. Under the optimized conditions, the recoveries were ranged from 50.7% to 115.4% with the relative standard deviations lower than 10%. The limits of detection were in the range of 0.03-0.30 microg/L and the limits of quantification were in the range of 0.15-1.50 microg/L. The method has been successfully applied to monitor the occurrence of the PPCPs residues in agricultural irrigation water in Dongguan, Guangdong Province. The four compounds were detected at maximum mass concentration range of 0.176-0.998 microg/L. It proved that this analytical method is sensitive, reliable and acceptable.

  13. Quantitative ester analysis in cachaca and distilled spirits by gas chromatography-mass spectrometry (GC-MS).

    PubMed

    Nascimento, Eduardo S P; Cardoso, Daniel R; Franco, Douglas W

    2008-07-23

    An analytical procedure for the separation and quantification of ethyl acetate, ethyl butyrate, ethyl hexanoate, ethyl lactate, ethyl octanoate, ethyl nonanoate, ethyl decanoate, isoamyl octanoate, and ethyl laurate in cachaca, rum, and whisky by direct injection gas chromatography-mass spectrometry was developed. The analytical method is simple, selective, and appropriated for the determination of esters in distilled spirits. The limit of detection ranged from 29 (ethyl hexanoate) to 530 (ethyl acetate) microg L(-1), whereas the standard deviation for repeatability was between 0.774% (ethyl hexanoate) and 5.05% (isoamyl octanoate). Relative standard deviation values for accuracy vary from 90.3 to 98.5% for ethyl butyrate and ethyl acetate, respectively. Ethyl acetate was shown to be the major ester in cachaca (median content of 22.6 mg 100 mL(-1) anhydrous alcohol), followed by ethyl lactate (median content of 8.32 mg 100 mL(-1) anhydrous alcohol). Cachaca produced in copper and hybrid alembic present a higher content of ethyl acetate and ethyl lactate than those produced in a stainless-steel column, whereas cachaca produced by distillation in a stainless-steel column present a higher content of ethyl octanoate, ethyl decanoate, and ethyl laurate. As expected, ethyl acetate is the major ester in whiskey and rum, followed by ethyl lactate for samples of rum. Nevertheless, whiskey samples exhibit ethyl lactate at contents lower or at the same order of magnitude of the fatty esters.

  14. Determination of Volatile Compounds in Four Commercial Samples of Japanese Green Algae Using Solid Phase Microextraction Gas Chromatography Mass Spectrometry

    PubMed Central

    Yoshikawa, Keisuke; Fujita, Akira; Mase, Nobuyuki; Watanabe, Naoharu

    2014-01-01

    Green algae are of great economic importance. Seaweed is consumed fresh or as seasoning in Japan. The commercial value is determined by quality, color, and flavor and is also strongly influenced by the production area. Our research, based on solid phase microextraction gas chromatography mass spectrometry (SPME-GC-MS), has revealed that volatile compounds differ intensely in the four varieties of commercial green algae. Accordingly, 41 major volatile compounds were identified. Heptadecene was the most abundant compound from Okayama (Ulva prolifera), Tokushima (Ulva prolifera), and Ehime prefecture (Ulva linza). Apocarotenoids, such as ionones, and their derivatives were prominent volatiles in algae from Okayama (Ulva prolifera) and Tokushima prefecture (Ulva prolifera). Volatile, short chained apocarotenoids are among the most potent flavor components and contribute to the flavor of fresh, processed algae, and algae-based products. Benzaldehyde was predominant in seaweed from Shizuoka prefecture (Monostroma nitidum). Multivariant statistical analysis (PCA) enabled simple discrimination of the samples based on their volatile profiles. This work shows the potential of SPME-GC-MS coupled with multivariant analysis to discriminate between samples of different geographical and botanical origins and form the basis for development of authentication methods of green algae products, including seasonings. PMID:24592162

  15. A fast gas chromatography/mass spectrometry method for the determination of stimulants and narcotics in urine.

    PubMed

    Strano Rossi, Sabina; de la Torre, Xavier; Botrè, Francesco

    2010-05-30

    A fast method has been developed for the simultaneous determination of 52 stimulants and narcotics excreted unconjugated in urine by gas chromatography/mass spectrometry (GC/MS). The procedure involves the liquid/liquid extraction of the analytes from urine at strong alkaline pH and the injection of the extract into a GC/MS instrument with a fast GC column (10 m x 0.18 mm i.d.); the short column allows the complete separation of the 52 analytes in a chromatographic run of 8 min. The method has been fully validated giving lower limits of detection (LLODs) satisfactory for its application to antidoping analysis as well as to forensic toxicology. The repeatability of the concentrations and the retention times are good both for intra- and for inter-day experiments (%CV of concentrations always lower than 15 and %CV of retention times lower than 0.6). In addition, the analytical bias is satisfactory (A% always >15%). The method proposed here would be particularly useful whenever there are time constraints and the analyses have to be completed in the shortest possible time. Copyright 2010 John Wiley & Sons, Ltd.

  16. Thermospray Liquid Chromatography/Mass Spectrometry (TSP LC/MS) Analysis of the Alkaloids from Cinchona in vitro Cultures.

    PubMed

    Giroud, C; van der Leer, T; van der Heijden, R; Verpoorte, R; Heeremans, C E; Niessen, W M; Vander Greef, J

    1991-04-01

    The alkaloids from CINCHONA LEDGERIANA shoot cultures and from CINCHONA ROBUSTA shoot cultures and a compact globular structure (CGS) culture were analyzed by thermospray liquid chromatography/mass spectrometry (TSP LC/MS). Because of the relative stability of the alkaloids under TSP discharge ionization conditions, a protonated molecule was observed in the mass spectra with hardly any fragmentation. When the reference compounds were available, the knowledge of the molecular mass and of the retention time was sufficient to identify most of the alkaloids. HPLC with UV photodiode-array detection complemented LC/MS perfectly by providing information about the aromatic part of the alkaloids (structure and substitution pattern). New alkaloids detected in CINCHONA IN VITRO cultures were 5-methoxytryptamine and corynantheal. In order to determine whether 5-methoxytryptamine was a precursor of the methoxylated quinolines, this indole was incubated with secologanin and several CINCHONA ROBUSTA crude protein extracts. Under all conditions tested, the coupling of 5-methoxytryptamine with secologanin remained unsuccessful. Only tryptamine condensed with secologanin to yield strictosidine. These results indicate that CINCHONA cells are able to methoxylate simple indoles like tryptamine and that 5-methoxytryptamine is very likely not used for the subsequent biosynthesis of the methoxylated quinolines.

  17. Natural resins and balsams from an eighteenth-century pharmaceutical collection analysed by gas chromatography/mass spectrometry.

    PubMed

    Steigenberger, Gundel; Herm, Christoph

    2011-10-01

    Historical nomenclature has not always been unequivocally associated with the botanical origin of natural resins. The availability of natural resins has changed throughout the centuries and so have their trade names. Furthermore, adulterations and lack of knowledge have led to variations in the composition of the products traded under the same name. This investigation aims at a new understanding of the interrelation between the historical and modern terms for natural resins. Different Pinaceae and Pistacia resins, mastic, sandarac, copaiba balm and burgundy pitch from Vigani's Cabinet, a 300-year-old pharmaceutical collection owned by Queens' College, Cambridge (UK) were investigated. Related reference materials from modern collections were analysed together with natural resins derived from reliable botanical sources. The analytical method was gas chromatography/mass spectrometry (GC-MS) with and without derivatisation with trimethylsulfonium hydroxide. This technique provided detailed molecular compositions of the studied materials, which in turn led to particular data profiles of the materials. Marker molecules of Copaifera, Pinaceae, Cupressaceae and Pistacia resins were identified. By comparing the GC-MS data profiles to the reference samples, a clearer picture of the connection between nomenclature and botanical origin was obtained. With the aid of the marker molecules and data profiles, it was then possible to clarify the nomenclature of the aged resins sampled from Vigani's Cabinet.

  18. Characterization of the volatile profiles of beer using headspace solid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Rossi, Serena; Sileoni, Valeria; Perretti, Giuseppe; Marconi, Ombretta

    2014-03-30

    The objective of this study was a multivariate characterization of the volatile profile of beers. Such a characterization is timely considering the increasing worldwide consumption of beer, the continuous growth of microbreweries and the importance of volatile compounds to beer flavour. A method employing solid-phase microextraction and gas chromatography-mass spectrometry (SPME-GC-MS) was optimized and then applied to a sample set of 36 industrial and craft beers of various styles and fermentation types. The volatile profiles of different beer styles is described, with particular attention paid to the volatile compounds characteristic of a spontaneously fermented lambic raspberry framboise beer. Furthermore, it was also possible to identify which specific volatile compounds are principally responsible for the differences in the volatile profiles of top- and bottom-fermented beers. Moreover, a volatile fingerprint of the craft top-fermented Italian beers was defined, as they show a very similar volatile profile. Finally, the volatile compounds that are characteristic of the bock-style beers are described. The SPME-GC-MS analytical method optimized in this study is suitable for characterizing the volatile fingerprint of different beers, especially on the basis of the kind of fermentation (top, bottom or spontaneous), the method of production and the style of the beer. © 2013 Society of Chemical Industry.

  19. Profile of volatile compounds in 11 brandies by headspace solid-phase microextraction followed by gas chromatography-mass spectrometry.

    PubMed

    Zhao, Y; Xu, Y; Li, J; Fan, W; Jiang, W

    2009-03-01

    A headspace solid-phase microextraction (HS-SPME) method coupled with gas chromatography-mass spectrometry (GC-MS) was applied for the qualitative or semiquantitative characterization of brandy volatiles. SPME variables (SPME fiber, extraction temperature and time, and ethanol concentration) were optimized. A total of 144 compounds were from the brandies' volatiles, tentatively identified or identified by comparing mass spectra and retention indices of the standards or from literature. Of these, 57 are common to 11 brandies. They were mainly represented by esters and alcohols, such as 2-methyl propanol, 3-methyl butanol, 1-hexanol, ethyl octanoate, and ethyl decanoate, which were quantitatively determined. Chromatographic peaks were integrated using selective ion method (SIM) and the semiquantitative data analyzed using principal component analysis (PCA) and cluster analysis (CA) to study relationships between volatile composition and brandy. Eleven brandies were differentiated into 3 groups: 1 for Hennessy VSOP and XO samples, 1 for Changyu PEGASE VSOP and XO-1, 2, 3 samples, and the other for Changyu PEGASE brandy and VO, Taro brandy, Baiyang River brandy, and Wealth XO samples. The classification of groups is consistent with the brandy samples by variety and grade.

  20. Evidence of lipid degradation during overnight contact lens wear: gas chromatography mass spectrometry as the diagnostic tool.

    PubMed

    Panaser, Amandeep; Tighe, Brian J

    2014-03-20

    We investigated structural differences in the fatty acid profiles of lipids extracted from ex vivo contact lenses by using gas chromatography mass spectrometry (GCMS). Two lens materials (balafilcon A or lotrafilcon A) were worn on a daily or continuous wear schedule for 30 and 7 days. Lipids from subject-worn lenses were extracted using 1:1 chloroform: methanol and transmethylated using 5% sulfuric acid in methanol. Fatty acid methyl esters (FAMEs) were collected using hexane and water, and analyzed by GCMS (Varian 3800 GC, Saturn 2000 MS). The gas chromatograms of lens extracts that were worn on a continuous wear schedule showed two predominant peaks, C16:0 and C18:0, both of which are saturated fatty acids. This was the case for balafilcon A and lotrafilcon A lenses. However, the gas chromatograms of lens extracts that were worn on a daily wear schedule showed saturated (C16:0, C18:0) and unsaturated (C16:1 and C18:1) fatty acids. Unsaturated fatty acids are degraded during sleep in contact lenses. Degradation occurred independently of lens material or subject-to-subject variability in lipid deposition. The consequences of lipid degradation are the production of oxidative products, which may be linked to contact lens discomfort.

  1. Gas Chromatography- Mass Spectrometry Based Metabolomic Approach for Optimization and Toxicity Evaluation of Earthworm Sub-Lethal Responses to Carbofuran

    PubMed Central

    Saxena, Prem Narain

    2013-01-01

    Despite recent advances in understanding mechanism of toxicity, the development of biomarkers (biochemicals that vary significantly with exposure to chemicals) for pesticides and environmental contaminants exposure is still a challenging task. Carbofuran is one of the most commonly used pesticides in agriculture and said to be most toxic carbamate pesticide. It is necessary to identify the biochemicals that can vary significantly after carbofuran exposure on earthworms which will help to assess the soil ecotoxicity. Initially, we have optimized the extraction conditions which are suitable for high-throughput gas chromatography mass spectrometry (GC-MS) based metabolomics for the tissue of earthworm, Metaphire posthuma. Upon evaluation of five different extraction solvent systems, 80% methanol was found to have good extraction efficiency based on the yields of metabolites, multivariate analysis, total number of peaks and reproducibility of metabolites. Later the toxicity evaluation was performed to characterize the tissue specific metabolomic perturbation of earthworm, Metaphire posthuma after exposure to carbofuran at three different concentration levels (0.15, 0.3 and 0.6 mg/kg of soil). Seventeen metabolites, contributing to the best classification performance of highest dose dependent carbofuran exposed earthworms from healthy controls were identified. This study suggests that GC-MS based metabolomic approach was precise and sensitive to measure the earthworm responses to carbofuran exposure in soil, and can be used as a promising tool for environmental eco-toxicological studies. PMID:24324663

  2. Measurement of volatile plant compounds in field ambient air by thermal desorption-gas chromatography-mass spectrometry.

    PubMed

    Cai, Xiao-Ming; Xu, Xiu-Xiu; Bian, Lei; Luo, Zong-Xiu; Chen, Zong-Mao

    2015-12-01

    Determination of volatile plant compounds in field ambient air is important to understand chemical communication between plants and insects and will aid the development of semiochemicals from plants for pest control. In this study, a thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) method was developed to measure ultra-trace levels of volatile plant compounds in field ambient air. The desorption parameters of TD, including sorbent tube material, tube desorption temperature, desorption time, and cold trap temperature, were selected and optimized. In GC-MS analysis, the selected ion monitoring mode was used for enhanced sensitivity and selectivity. This method was sufficiently sensitive to detect part-per-trillion levels of volatile plant compounds in field ambient air. Laboratory and field evaluation revealed that the method presented high precision and accuracy. Field studies indicated that the background odor of tea plantations contained some common volatile plant compounds, such as (Z)-3-hexenol, methyl salicylate, and (E)-ocimene, at concentrations ranging from 1 to 3400 ng m(-3). In addition, the background odor in summer was more abundant in quality and quantity than in autumn. Relative to previous methods, the TD-GC-MS method is more sensitive, permitting accurate qualitative and quantitative measurements of volatile plant compounds in field ambient air.

  3. Determination of macrolide antibiotics in meat and fish using pressurized liquid extraction and liquid chromatography-mass spectrometry.

    PubMed

    Berrada, Houda; Borrull, Francesc; Font, Guillermina; Marcé, Rosa Maria

    2008-10-24

    We developed a method for determining the quantities of seven macrolide antibiotics in meat and fish by using pressurized liquid extraction (PLE) and liquid chromatography-mass spectrometry with electrospray ionization (LC-(ESI)MS). The PLE was optimized with regard to solvents, temperature, pressure, extraction time and number of cycles. The optimum conditions were: methanol as the extraction solvent; a temperature of 80 degrees C; a pressure of 1500psi; an extraction time of 15min; 2 cycles; a flush volume of 150% and a purge time of 300s. All recoveries for macrolide antibiotics were over 77% at 200mug/kg, except for erythromycin, which was 58%. The repeatability and reproducibility on days in between, expressed as %RSD (n=12), were lower than 10% and 12%, respectively. The quantification limits of all compounds were 25mug/kg of dry weight of animal muscle except for troleandomycin (50mug/kg). The method was applied to determine the pharmaceuticals in real samples taken from 18 meat and fish samples. The results showed that PLE is quantitative short time consuming technique, with use of smaller initial sample sizes. Greater specificity and selectivity in extraction and increased potential for automation were shown.

  4. [Analysis of pesticide multiresidues in rice by gas chromatography-mass spectrometry coupled with solid phase extraction].

    PubMed

    Liu, Pengyan; Liu, Qingxue; Ma, Yusong; Liu, Jinwei; Jia, Xuan

    2006-05-01

    A new analytical method was developed to simultaneously determine multiple pesticide residues in rice including organophosphorus, organochlorine, carbamate and pyrethroid. First, the solvents for pesticide extraction were selected for optimization. Eight solvents were screened to find that the extraction efficiency with dichloromethane was the best. Second, clean-up was performed by solid phase extraction using a Florisil cartridge. Various mixtures of hexane and acetone were tested to show that the mixture of hexane-acetone (4:1, v/v) had the best performance. The clean-up helped the sample purification significantly. The prepared sample was analyzed using gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode. The pesticides were identified with retention time and selected ions and their relative abundances, and they were quantified based on extract of spiking standards in a blank sample. The limits of detection (LODs) were evaluated on the values of the lower concentration fortified sample under the signal-to-noise ratio of 3:1. The recoveries and relative standard deviations (RSDs) were checked by adding pesticide standard solution at two levels to untreated samples, and the triplicate analysis of the samples were carried out for each spiked level. The LODs were at microg/kg level. The average recoveries of most pesticides were from 75% to 120 %. The RSDs were less than 10.4% (n = 3). These results indicated that this method is simple, rapid, sensitive for the simultaneous determination requirements of multiple pesticide residues in rice.

  5. Determination of polycyclic aromatic hydrocarbons in fresh milk by hollow fiber liquid-phase microextraction-gas chromatography mass spectrometry.

    PubMed

    Sanagi, Mohd Marsin; Loh, Saw Hong; Wan Ibrahim, Wan Aini; Hasan, Mohamed Noor; Aboul Enein, Hassan Y

    2013-02-01

    In this work, a two-phase hollow fiber liquid-phase microextraction (HF-LPME) method combined with gas chromatography-mass spectrometry (GC-MS) is developed to provide a rapid, selective and sensitive analytical method to determine polycyclic aromatic hydrocarbons (PAHs) in fresh milk. The standard addition method is used to construct calibration curves and to determine the residue levels for the target analytes, fluorene, phenanthrene, fluoranthene, pyrene and benzo[a]pyrene, thus eliminating sample pre-treatment steps such as pH adjustment. The HF-LPME method shows dynamic linearity from 5 to 500 µg/L for all target analytes with R(2) ranging from 0.9978 to 0.9999. Under optimized conditions, the established detection limits range from 0.07 to 1.4 µg/L based on a signal-to-noise ratio of 3:1. Average relative recoveries for the determination of PAHs studied at 100 µg/L spiking levels are in the range of 85 to 110%. The relative recoveries are slightly higher than those obtained by conventional solvent extraction, which requires saponification steps for fluorene and phenanthrene, which are more volatile and heat sensitive. The HF-LPME method proves to be simple and rapid, and requires minimal amounts of organic solvent that supports green analysis.

  6. Development of Sensitive and Specific Analysis of Vildagliptin in Pharmaceutical Formulation by Gas Chromatography-Mass Spectrometry

    PubMed Central

    Uçaktürk, Ebru

    2015-01-01

    A sensitive and selective gas chromatography-mass spectrometry (GC-MS) method was developed and fully validated for the determination of vildagliptin (VIL) in pharmaceutical formulation. Prior to GC-MS analysis, VIL was efficiently derivatized with MSTFA/NH4I/β-mercaptoethanol at 60°C for 30 min. The obtained O-TMS derivative of VIL was detected by selected ion monitoring mode using the diagnostic ions m/z 223 and 252. Nandrolone was chosen as internal standard. The GC-MS method was fully validated by the following validation parameters: limit of detection (LOD) and quantitation (LOQ), linearity, precision, accuracy, specificity, stability, robustness, and ruggedness. LOD and LOQ were found to be 1.5 and 3.5 ng mL−1, respectively. The GC-MS method is linear in the range of 3.5–300 ng mL−1. The intra- and interday precision values were less than ≤3.62%. The intra- and interday accuracy values were found in the range of −0.26–2.06%. Finally, the GC-MS method was successfully applied to determine VIL in pharmaceutical formulation. PMID:26682085

  7. Direct sample introduction-gas chromatography-mass spectrometry for the determination of haloanisole compounds in cork stoppers.

    PubMed

    Cacho, J I; Nicolás, J; Viñas, P; Campillo, N; Hernández-Córdoba, M

    2016-12-02

    A solventless analytical method is proposed for analyzing the compounds responsible for cork taint in cork stoppers. Direct sample introduction (DSI) is evaluated as a sample introduction system for the gas chromatography-mass spectrometry (GC-MS) determination of four haloanisoles (HAs) in cork samples. Several parameters affecting the DSI step, including desorption temperature and time, gas flow rate and other focusing parameters, were optimized using univariate and multivariate approaches. The proposed method shows high sensitivity and minimises sample handling, with detection limits of 1.6-2.6ngg(-1), depending on the compound. The suitability of the optimized procedure as a screening method was evaluated by obtaining decision limits (CCα) and detection capabilities (CCβ) for each analyte, which were found to be in 6.9-11.8 and 8.7-14.8ngg(-1), respectively, depending on the compound. Twenty-four cork samples were analysed, and 2,4,6-trichloroanisole was found in four of them at levels between 12.6 and 53ngg(-1). Copyright © 2016 Elsevier B.V. All rights reserved.

  8. An improved method for cyanide determination in blood using solid-phase microextraction and gas chromatography/mass spectrometry.

    PubMed

    Frison, Giampietro; Zancanaro, Flavio; Favretto, Donata; Ferrara, Santo Davide

    2006-01-01

    A new method is described for the qualitative and quantitative analysis of cyanide, a very short-acting and powerful toxic agent, in human whole blood. It involves the conversion of cyanide into hydrogen cyanide and its subsequent headspace solid-phase microextraction (HS-SPME) and detection by gas chromatography/mass spectrometry (GC/MS) in selected ion monitoring (SIM) mode. Optimizing the conditions for the GC/MS (type of column, injection conditions, temperature program) and SPME (choice of SPME fiber, effect of salts, adsorption and desorption times, adsorption temperature) led to the choice of a 75-microm carboxen/polydimethylsiloxane SPME fiber, with D3-acetonitrile as internal standard, and a capillary GC column with a polar stationary phase. Method validation was carried out in terms of linearity, precision and accuracy in both aqueous solutions and blood. The limit of detection (LOD) and limit of quantitation (LOQ) were determined only in aqueous solutions. The assay is linear over three orders of magnitude (water 0.01-10, blood 0.05-10 microg/mL); and the LOD and LOQ in water were 0.006 and 0.01 microg/mL, respectively. Good intra- and inter-assay precision was obtained, always <8%. The method is simple, fast and sensitive enough for the rapid diagnosis of cyanide intoxication in clinical and forensic toxicology.

  9. Hollow-fiber liquid phase microextraction for lignin pyrolysis acids in aerosol samples and gas chromatography-mass spectrometry analysis.

    PubMed

    Hyder, Murtaza; Jönsson, Jan Åke

    2012-08-03

    A method based on three-phase hollow fiber liquid phase microextraction was developed and successfully applied to aerosols for the analysis of lignin pyrolysis acids such as syringic acid, vanillic acid and p-salicylic acid. Important parameters related to extraction process like organic solvent for membrane phase, tri-n-octylphosphine (TOPO) oxide contents in organic solvent, stirring speed, extraction time etc. were optimized. 6-Undecanone with 15% TOPO contents (w/v) was found a suitable solvent for organic liquid membrane, 900 rpm was the optimum stirring speed and time of 4h was found optimum extraction time. Donor phase pH was 1.3 while acceptor phase pH was adjusted to 9.5. The optimized extraction method was used for the extraction of real aerosol samples. Analytes were derivatized using BSTFA containing 1% trimethylsilyl chloride and gas chromatography mass spectrometry was used for analysis. Very low limits of detection in the range 0.2-1.0 ng L(-1) were found, corresponding to 10-50 pg m(-3) of analytes in aerosols. Extraction efficiency obtained ranged 60.3-71.7% and enrichment factors ranged 3015-3585 times. The optimized method was successfully applied to aerosol samples and all of the selected analytes were detected in the analyzed samples. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Simultaneous Determination of Tramadol and Its Metabolite in Human Urine by the Gas Chromatography-Mass Spectrometry Method.

    PubMed

    Yilmaz, Bilal; Erdem, Ali Fuat

    2015-08-01

    A sensitive and efficient method was developed for determination of tramadol and its metabolite (O-desmethyltramadol) in human urine by gas chromatography-mass spectrometry. Tramadol, O-desmethyltramadol and medazepam (internal standard) were extracted from human urine with a mixture of ethylacetate and diethylether mixture (1 : 1, v/v) at basic pH with liquid-liquid extraction. The calibration curves were linear (r = 0.99) over tramadol and O-desmethyltramadol concentrations ranging from 10 to 200 ng/mL and 7.5 to 300 ng/mL, respectively. The method had an accuracy of >95% and intra- and interday precision (relative standard deviation %) of ≤4.93 and ≤4.62% for tramadol and O-desmethyltramadol, respectively. The extraction recoveries were found to be 94.1 ± 2.91 and 96.3 ± 3.46% for tramadol and O-desmethyltramadol, respectively. The limit of quantification using 0.5 mL human urine was 10 ng/mL for tramadol and 7.5 ng/mL for O-desmethyltramadol. After oral administration of 100 mg of tramadol hydrochloride to a patient, the urinary excretion was monitored during 24 h. About 15% of the dose was excreted as unchanged tramadol. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. Coupling liquid chromatography/mass spectrometry detection with microfluidic droplet array for label-free enzyme inhibition assay.

    PubMed

    Wang, Xiu-Li; Zhu, Ying; Fang, Qun

    2014-01-07

    In this work, the combination of droplet-based microfluidics with liquid chromatography/mass spectrometry (LC/MS) was achieved, for providing a fast separation and high-information-content detection method for the analysis of nanoliter-scale droplets with complex compositions. A novel interface method was developed using an oil-covered droplet array chip to couple with an LC/MS system via a capillary sampling probe and a 4 nL injection valve without the need of a droplet extraction device. The present system can perform multistep operations including parallel enzyme inhibition reactions in nanoliter droplets, 4 nL sample injection, fast separation with capillary LC, and label-free detection with ESI-MS, and has significant flexibility in the accurate addressing and sampling of droplets of interest on demand. The system performance was evaluated using angiotensin I and angiotensin II as model samples, and the repeatabilities of peak area for angiotensin I and angiotensin II were 2.7% and 7.5% (RSD, n = 4), respectively. The present system was further applied to the screening for inhibitors of cytochrome P450 (CYP1A2) and measurement of the IC50 value of the inhibitor. The sample consumption for each droplet assay was 100 nL, which is reduced 10-100 times compared with conventional 384-multi-well plate systems usually used in high-throughput drug screening.

  12. Simultaneous determination of 76 micropollutants in water samples by headspace solid phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Martínez, C; Ramírez, N; Gómez, V; Pocurull, E; Borrull, F

    2013-11-15

    This study focuses on the development of an analytical method based on headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) for the simultaneous determination of 76 micropollutants in water samples. The selected micropollutants include volatile organic compounds (VOCs) (e.g. chlorobenzenes, chloroalkanes), endocrine disrupting compounds (EDCs) (e.g. bisphenol A and tributyl phosphate), odour compounds (e.g. limonene, phenol), fragrance allergens (e.g. geraniol, eugenol) and some pesticides (e.g. heptachlor, terbutryn). The experimental conditions affecting their extraction, such as the type of fibre, temperature and time of extraction, sample volume and ionic strength of the samples were optimized using HS-SPME. The method showed good linear range, reproducibility between days, repeatability and low detection limits (at ng L(-1) levels). The validated method has been applied to determine the target organic micropollutants in aqueous samples from different experimental research units of surface water, sea water, waste water and those effluents of advance membrane treatments. The optimized method showed good performance in the different types of samples studied. The analysis revealed the presence of several micropollutants at concentrations between 20 and 5000 μg L(-1), such as ethylbenzene, o-xylene, p-isopropilbenzene, D-limonene, citral and isoeugenol, due to the fact that these species are commonly used in domestic and industrial applications.

  13. Static headspace-gas chromatography-mass spectrometry for the simultaneous determination of trihalomethanes and haloacetic acids in canned vegetables.

    PubMed

    Cardador, Maria Jose; Gallego, Mercedes

    2016-07-08

    Canned vegetables appear to be a possible exposure pathway for hazardous disinfection by-products due to the use of sanitizers and treated water by the canning industry in the preparation of these foods. This work reports on two static headspace-gas chromatography-mass spectrometry methods for the simultaneous determination of 10 trihalomethanes (THMs) and 13 haloacetic acids (HAAs) in both solid and liquid phases of the canned vegetables. Both methods carry out the whole process (including the leaching of target analytes from the vegetable), derivatization of HAAs and volatilization of THMs and HAA esters, in a single step within a static headspace unit. The methods proposed provide an efficient and simple tool for the determination of regulated disinfection by-products in canned vegetables. Average limits of detection for THMs and HAAs were 0.19 and 0.45μg/kg, respectively, in the solid phase of canned vegetables, and 0.05 and 0.09μg/L, respectively, in the liquid phase. Satisfactory recoveries (90-99%) and precision, calculated as relative standard deviations (RSD≤10%), were obtained in both phases of canned vegetables. The methods proposed were applied for the analysis of frequently-used canned vegetables and confirmed the presence of up to 3 THMs and 5 HAAs at microgram per kilogram or liter levels in both phases of the samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Headspace-trap gas chromatography-mass spectrometry for determination of sulphur mustard and related compounds in soil.

    PubMed

    Røen, Bent T; Unneberg, Erik; Tørnes, John Aa; Lundanes, Elsa

    2010-04-02

    Methods for trace determination of sulphur mustard (HD) and some related cyclic sulphur compounds in soil samples have been developed using headspace-trap in combination with gas chromatography-mass spectrometry (GC-MS). Two quite different types of soil were employed in the method optimisation (sandy loam and silty clay loam). Prior to analysis, water saturated with sodium chloride was added to the samples, at a water to soil ratio of 1:1. A detection limit of 3 ng/g was achieved for HD, while the cyclic sulphur compounds 1,4-thioxane, 1,3-dithiolane and 1,4-dithiane could be detected at 0.2-0.7 ng/g. The methods were validated in the concentration range from the limit of quantification (LOQ) to hundred times LOQ. The within assay precision at fifty times LOQ was 6.9-7.3% relative standard deviation (RSD) for determination of the cyclic sulphur compounds, and 15% RSD for determination of HD. Recoveries were in the range of 43-60% from the two soil types. As the technique requires very little sample preparation, the total time for sample handling and analysis was less than 1h. The technique was successfully employed for the determination of cyclic sulphur compounds in a sediment sample from an old dumping site for chemical munitions, known to contain HD degradation products. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  15. Improved detection of multi-phosphorylated peptides in the presence of phosphoric acid in liquid chromatography/mass spectrometry

    SciTech Connect

    Kim, Jeongkwon; Camp, David G.; Smith, Richard D.

    2004-02-18

    In contrast to lower phosphorylation states (e.g., the tryptic monophosphopeptide FQpSEEQQQTEDELQDK from bovine -casein), the specific detection of multi-phosphorylated peptides (e.g. the tetraphosphopeptide RELEELNVPGEIVEpSLpSpSpSEESITR from tryptic digestion of bovine -casein) has often been problematic for liquid chromatography-mass spectrometry analysis due to their high affinity for adsorption to exposed surfaces. We observed an enhancement in the overall detection of phosphopeptides upon addition of phosphoric acid (0.1% to 1.0%) to the sample solution; a 10-fold increase in sensitivity was measured for the detection of two tryptic phosphopeptides as well as a significant improvement in the detection of the tetraphosphopeptide. Using capillary LC with an ion trap tandem mass spectrometer for detection and identification, the achievable detection limits were 50 fmol and 50 pmol for the monophosphopeptide and the tetraphosphopeptide, respectively. Phosphoric acid is believed to act as a blocking agent to available silanol groups on both the silica capillary surface and the C-18-bonded silica surface.

  16. Analysis of ammonium nitrate headspace by on-fiber solid phase microextraction derivatization with gas chromatography mass spectrometry.

    PubMed

    Lubrano, Adam L; Andrews, Benjamin; Hammond, Mark; Collins, Greg E; Rose-Pehrsson, Susan

    2016-01-15

    A novel analytical method has been developed for the quantitation of trace levels of ammonia in the headspace of ammonium nitrate (AN) using derivatized solid phase microextraction (SPME) fibers with gas chromatography mass spectrometry (GC-MS). Ammonia is difficult to detect via direct injection into a GC-MS because of its low molecular weight and extreme polarity. To circumvent this issue, ammonia was derivatized directly onto a SPME fiber by the reaction of butyl chloroformate coated fibers with the ammonia to form butyl carbamate. A derivatized externally sampled internal standard (dESIS) method based upon the reactivity of diethylamine with unreacted butyl chloroformate on the SPME fiber to form butyl diethylcarbamate was established for the reproducible quantification of ammonia concentration. Both of these compounds are easily detectable and separable via GC-MS. The optimized method was then used to quantitate the vapor concentration of ammonia in the headspace of two commonly used improvised explosive device (IED) materials, ammonium nitrate fuel oil (ANFO) and ammonium nitrate aluminum powder (Ammonal), as well as identify the presence of additional fuel components within the headspace.

  17. Determination of volatile compounds in four commercial samples of Japanese green algae using solid phase microextraction gas chromatography mass spectrometry.

    PubMed

    Yamamoto, Masayoshi; Baldermann, Susanne; Yoshikawa, Keisuke; Fujita, Akira; Mase, Nobuyuki; Watanabe, Naoharu

    2014-01-01

    Green algae are of great economic importance. Seaweed is consumed fresh or as seasoning in Japan. The commercial value is determined by quality, color, and flavor and is also strongly influenced by the production area. Our research, based on solid phase microextraction gas chromatography mass spectrometry (SPME-GC-MS), has revealed that volatile compounds differ intensely in the four varieties of commercial green algae. Accordingly, 41 major volatile compounds were identified. Heptadecene was the most abundant compound from Okayama (Ulva prolifera), Tokushima (Ulva prolifera), and Ehime prefecture (Ulva linza). Apocarotenoids, such as ionones, and their derivatives were prominent volatiles in algae from Okayama (Ulva prolifera) and Tokushima prefecture (Ulva prolifera). Volatile, short chained apocarotenoids are among the most potent flavor components and contribute to the flavor of fresh, processed algae, and algae-based products. Benzaldehyde was predominant in seaweed from Shizuoka prefecture (Monostroma nitidum). Multivariant statistical analysis (PCA) enabled simple discrimination of the samples based on their volatile profiles. This work shows the potential of SPME-GC-MS coupled with multivariant analysis to discriminate between samples of different geographical and botanical origins and form the basis for development of authentication methods of green algae products, including seasonings.

  18. Solid phase microextraction and gas chromatography-mass spectrometry methods for residual solvent assessment in seized cocaine and heroin.

    PubMed

    Cabarcos, Pamela; Herbello-Hermelo, Paloma; Álvarez-Freire, Iván; Moreda-Piñeiro, Antonio; Tabernero, María Jesús; Bermejo, Ana María; Bermejo-Barrera, Pilar

    2016-09-01

    A simple sample pre-treatment method based on solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) has been optimized and validated for the assessment of 15 residual solvents (2-propanol, 2-methylpentane, 3-methylpentane, acetone, ethyl acetate, benzene, hexane, methylcyclohexane, methylcyclopentane, m-xylene, propyl acetate, toluene, 1,2,4-trimethylbenzene, dichloromethane, and ethylbenzene) in seized illicit cocaine and heroin. DMSO and DMF as sample diluents were found to offer the best residual solvent transference to the head space for further adsorption onto the SPME fiber, and the developed method therefore showed high sensitivity and analytical recovery. Variables affecting SPME were fully evaluated by applying an experimental design approach. Best conditions were found when using an equilibration time of 5 min at 70 °C and headspace sampling of residual solvents at the same temperature for 15 min. Method validation, performed within the requirements of international guidelines, showed excellent sensitivity, as well as intra- and inter-day precision and accuracy. The proposed methodology was applied to 96 cocaine samples and 14 heroin samples seized in Galicia (northwestern Spain) within 2013 and 2014.

  19. Quality evaluation of green tea leaf cultured under artificial light condition using gas chromatography/mass spectrometry.

    PubMed

    Miyauchi, Shunsuke; Yonetani, Tsutomu; Yuki, Takayuki; Tomio, Ayako; Bamba, Takeshi; Fukusaki, Eiichiro

    2017-02-01

    For an experimental model to elucidate the relationship between light quality during plant culture conditions and plant quality of crops or vegetables, we cultured tea plants (Camellia sinensis) and analyzed their leaves as tea material. First, metabolic profiling of teas from a tea contest in Japan was performed with gas chromatography/mass spectrometry (GC/MS), and then a ranking predictive model was made which predicted tea rankings from their metabolite profile. Additionally, the importance of some compounds (glutamine, glutamic acid, oxalic acid, epigallocatechin, phosphoric acid, and inositol) was elucidated for measurement of the quality of tea leaf. Subsequently, tea plants were cultured in artificial conditions to control these compounds. From the result of prediction by the ranking predictive model, the tea sample supplemented with ultraviolet-A (315-399 nm) showed the highest ranking. The improvement in quality was thought to come from the high amino-acid and decreased epigallocatechin content in tea leaves. The current study shows the use and value of metabolic profiling in the field of high-quality crops and vegetables production that has been conventionally evaluated by human sensory analysis. Metabolic profiling enables us to form hypothesis to understand and develop high quality plant cultured under artificial condition.

  20. Quantitative measurement of dihydrouridine in RNA using isotope dilution liquid chromatography-mass spectrometry (LC/MS).

    PubMed Central

    Dalluge, J J; Hashizume, T; McCloskey, J A

    1996-01-01

    A method has been developed for the microscale determination of 5,6-dihydrouridine, the most common post-transcriptional modification in bacterial and eukaryotic tRNA. The method is based on stable isotope dilution liquid chromatography-mass spectrometry (LC/MS) using [1,3-15N2]dihydrouridine and [1,3-15N2]uridine as internal standards. RNA samples were enzymatically digested to nucleosides before addition of the internal standards and subsequently analyzed by LC/MS with selected ion monitoring of protonated molecular ions of the labeled and unlabeled nucleosides. Sample quantities of approximately 1 pmol tRNA and 5 pmol 23S rRNA were analyzed for mole% dihydrouridine. Dihydrouridine content of Escherichia coli tRNASer(VGA) and tRNAThr(GGU) as controls were measured as 2.03 and 2.84 residues/tRNA molecule, representing accuracies of 98 and 95%. Overall precision values for the analyses of E. coli tRNASer(VGA) and E. coli tRNAThr(GGU), unfractionated tRNA from E. coli and 23S rRNA from E. coli were within the range 0.43-2.4%. The mole% dihydrouridine in unfractionated tRNA and 23S rRNA from E. coli were determined as 1.79 and 0.0396%, corresponding to 1.4 and 1.1 residues/RNA molecule respectively. PMID:8774907

  1. Mass spectral studies on vinylic degradation products of sulfur mustards under gas chromatography/mass spectrometry conditions.

    PubMed

    Sai Sachin, L; Karthikraj, R; Kalyan Kumar, K; Sony, T; Prasada Raju, N; Prabhakar, S

    2015-01-01

    Sulfur mustards are a class of vesicant chemical warfare agents that rapidly degrade in environmental samples. The most feasible degradation products of sulfur mustards are chloroethyl vinylic compounds and divinylic compounds, which are formed by the elimination of one and two HCl molecules from sulfur mustards, respectively. The detection and characterization of these degradation products in environmental samples are an important proof for the verification of sulfur mustard usage. In this study, we synthesized a set of sulfur mustard degradation products, i.e., divinylic compounds (1-7) and chloroethyl vinylic compounds (8-14), and characterized using gas chromatography/mass spectrometry (GC/MS) under electron ionization (EI) and chemical ionization (CI) (methane) conditions. The EI mass spectra of the studied compounds mainly included the fragment ions that resulted from homolytic cleavages with or without hydrogen migrations. The divinylic compounds (1-7) showed [M-SH](+) ions, whereas the chloroethylvinyl compounds (8-14) showed [M-Cl](+) and [M-CH2CH2Cl](+) ions. Methane/CI mass spectra showed [M+H](+) ions and provided molecular weight information. The GC retention index (RI) values were also calculated for the studied compounds. The EI and CI mass spectral data together with RI values are extremely useful for off-site analysis for the verification of the chemical weapons convention and also to participate in official Organization for the Prohibition of Chemical Weapons proficiency tests.

  2. Convenient analysis of vitamin D in cheese and other food matrixes by liquid chromatography/mass spectrometry.

    PubMed

    Dimartino, Gianluca

    2007-01-01

    A convenient method is presented for determination of vitamin D in natural cheese, processed cheese, milk, cereals, noncarbonated soft drinks, and juice by liquid chromatography/ mass spectrometry (LC/MS). Samples were saponified, extracted, evaporated, redissolved in acetonitrile, and injected into an LC-atmospheric pressure chemical ionization-MS system with no preparative chromatographic steps. Vitamin D was determined by selected ion monitoring. MS response was linear for vitamin D3 and its internal standard vitamin D2, and overall average recoveries ranged from 98 to 105%. A blending experiment in which shredded vitamin D3-fortified cheddar was mixed with control nonfortified cheddar showed linearity. The limit of detection for vitamin D was 1.3 ng and the limit of quantitation was 3 ng. The method gave good accuracy and precision, with a standard deviation of 9.5 and relative standard deviation of 6.7%. Results for vitamin D3 obtained with this method for different food matrixes, at different levels, were in agreement with those obtained with the reference LC/UV method currently used by many laboratories and derived from AOAC Official Method 982.29.

  3. Determination of Levetiracetam in Human Plasma by Dispersive Liquid-Liquid Microextraction Followed by Gas Chromatography-Mass Spectrometry

    PubMed Central

    2016-01-01

    Levetiracetam (LEV) is an antiepileptic drug that is clinically effective in generalized and partial epilepsy syndromes. The use of this drug has been increasing in clinical practice and intra- or -interindividual variability has been exhibited for special population. For this reason, bioanalytical methods are required for drug monitoring in biological matrices. So this work presents a dispersive liquid-liquid microextraction method followed by gas chromatography-mass spectrometry (DLLME-GC-MS) for LEV quantification in human plasma. However, due to the matrix complexity a previous purification step is required. Unlike other pretreatment techniques presented in the literature, for the first time, a procedure employing ultrafiltration tubes Amicon® (10 kDa porous size) without organic solvent consumption was developed. GC-MS analyses were carried out using a linear temperature program, capillary fused silica column, and helium as the carrier gas. DLLME optimized parameters were type and volume of extraction and dispersing solvents, salt addition, and vortex agitation time. Under chosen parameters (extraction solvent: chloroform, 130 μL; dispersing solvent: isopropyl alcohol, 400 μL; no salt addition and no vortex agitation time), the method was completely validated and all parameters were in agreement with the literature recommendations. LEV was quantified in patient's plasma sample using less than 550 μL of organic solvent. PMID:27830105

  4. Small Molecule Quantification by Liquid Chromatography-Mass Spectrometry for Metabolites of Drugs and Drug CandidatesS⃞

    PubMed Central

    Dahal, Upendra P.; Davis, John A.; Rock, Dan A.

    2011-01-01

    Identification and quantification of the metabolites of drugs and drug candidates are routinely performed using liquid chromatography-mass spectrometry (LC-MS). The best practice is to generate a standard curve with the metabolite versus the internal standard. However, to avoid the difficulties in metabolite synthesis, standard curves are sometimes prepared using the substrate, assuming that the signal for substrate and the metabolite will be equivalent. We have tested the errors associated with this assumption using a series of very similar compounds that undergo common metabolic reactions using both conventional flow electrospray ionization LC-MS and low-flow captive spray ionization (CSI) LC-MS. The differences in standard curves for four different types of transformations (O-demethylation, N-demethylation, aromatic hydroxylation, and benzylic hydroxylation) are presented. The results demonstrate that the signals of the substrates compared with those of the metabolites are statistically different in 18 of the 20 substrate-metabolite combinations for both methods. The ratio of the slopes of the standard curves varied up to 4-fold but was slightly less for the CSI method. PMID:21937735

  5. Metabolic profiling by gas chromatography-mass spectrometry of energy metabolism in high-fat diet-fed obese mice.

    PubMed

    Patel, Daxesh P; Krausz, Kristopher W; Xie, Cen; Beyoğlu, Diren; Gonzalez, Frank J; Idle, Jeffrey R

    2017-01-01

    A novel, selective and sensitive single-ion monitoring (SIM) gas chromatography-mass spectrometry (GCMS) method was developed and validated for the determination of energy metabolites related to glycolysis, the tricarboxylic acid (TCA) cycle, glutaminolysis, and fatty acid β-oxidation. This assay used N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide (MTBSTFA) containing 1% tert-butyldimethylchlorosilane (TBDMCS) as derivatizing reagent and was highly reproducible, sensitive, specific and robust. The assay was used to analyze liver tissue and serum from C57BL/6N obese mice fed a high-fat diet (HFD) and C57BL/6N mice fed normal chow for 8 weeks. HFD-fed mice serum displayed statistically significantly reduced concentrations of pyruvate, citrate, succinate, fumarate, and 2-oxoglutarate, with an elevated concentration of pantothenic acid. In liver tissue, HFD-fed mice exhibited depressed levels of glycolysis end-products pyruvate and lactate, glutamate, and the TCA cycle intermediates citrate, succinate, fumarate, malate, and oxaloacetate. Pantothenate levels were 3-fold elevated accompanied by a modest increased gene expression of Scl5a6 that encodes the pantothenate transporter SLC5A6. Since both glucose and fatty acids inhibit coenzyme A synthesis from pantothenate, it was concluded that these data were consistent with downregulated fatty acid β-oxidation, glutaminolysis, glycolysis, and TCA cycle activity, due to impaired anaplerosis. The novel SIM GCMS assay provided new insights into metabolic effects of HFD in mice.

  6. Metabolic profiling by gas chromatography-mass spectrometry of energy metabolism in high-fat diet-fed obese mice

    PubMed Central

    Patel, Daxesh P.; Krausz, Kristopher W.; Xie, Cen; Beyoğlu, Diren; Gonzalez, Frank J.

    2017-01-01

    A novel, selective and sensitive single-ion monitoring (SIM) gas chromatography-mass spectrometry (GCMS) method was developed and validated for the determination of energy metabolites related to glycolysis, the tricarboxylic acid (TCA) cycle, glutaminolysis, and fatty acid β-oxidation. This assay used N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide (MTBSTFA) containing 1% tert-butyldimethylchlorosilane (TBDMCS) as derivatizing reagent and was highly reproducible, sensitive, specific and robust. The assay was used to analyze liver tissue and serum from C57BL/6N obese mice fed a high-fat diet (HFD) and C57BL/6N mice fed normal chow for 8 weeks. HFD-fed mice serum displayed statistically significantly reduced concentrations of pyruvate, citrate, succinate, fumarate, and 2-oxoglutarate, with an elevated concentration of pantothenic acid. In liver tissue, HFD-fed mice exhibited depressed levels of glycolysis end-products pyruvate and lactate, glutamate, and the TCA cycle intermediates citrate, succinate, fumarate, malate, and oxaloacetate. Pantothenate levels were 3-fold elevated accompanied by a modest increased gene expression of Scl5a6 that encodes the pantothenate transporter SLC5A6. Since both glucose and fatty acids inhibit coenzyme A synthesis from pantothenate, it was concluded that these data were consistent with downregulated fatty acid β-oxidation, glutaminolysis, glycolysis, and TCA cycle activity, due to impaired anaplerosis. The novel SIM GCMS assay provided new insights into metabolic effects of HFD in mice. PMID:28520815

  7. Implementation of an Environmental Focus in an Undergraduate Chemistry Curriculum by the Addition of Gas Chromatography-Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Atterholt, Cynthia; Butcher, David J.; Bacon, J. Roger; Kwochka, William R.; Woosley, Royce

    2000-12-01

    The Department Chemistry and Physics at Western Carolina University has added an environmental focus to its curriculum, and gas chromatography-mass spectrometry (GC-MS) was identified as an essential tool in environmental analysis. GC-MS is used in undergraduate chemistry courses in: (i) the identification of synthesized compounds and natural products, (ii) monitoring compounds and their degradation in the environment, and (iii) analytical method development. In Organic Chemistry, the GC-MS is used to characterize natural products and the products of an environmentally benign chemical synthesis. In Environmental Chemistry, the GC-MS is used to identify compounds of environmental interest, such as pesticides in soil samples, polycyclic aromatic hydrocarbons in water, and hydrocarbons in gasoline samples. In Instrumental Analysis I, students characterize numerous compounds in cigarette smoke using GC-MS. In Instrumental Analysis II, students are presented with an analytical chemistry problem for which they research protocols, collect samples, and perform the analyses. The GC-MS has been used to identify volatile compounds in a number of complex mixtures. Also, research in chemistry is a significant part of our curriculum, and numerous undergraduate students have used the GC-MS in their research. The addition of GC-MS has enhanced many of our undergraduate laboratory courses and student-led research projects.

  8. Analytical platform for metabolome analysis of microbial cells using methyl chloroformate derivatization followed by gas chromatography-mass spectrometry.

    PubMed

    Smart, Kathleen F; Aggio, Raphael B M; Van Houtte, Jeremy R; Villas-Bôas, Silas G

    2010-09-01

    This protocol describes an analytical platform for the analysis of intra- and extracellular metabolites of microbial cells (yeast, filamentous fungi and bacteria) using gas chromatography-mass spectrometry (GC-MS). The protocol is subdivided into sampling, sample preparation, chemical derivatization of metabolites, GC-MS analysis and data processing and analysis. This protocol uses two robust quenching methods for microbial cultures, the first of which, cold glycerol-saline quenching, causes reduced leakage of intracellular metabolites, thus allowing a more reliable separation of intra- and extracellular metabolites with simultaneous stopping of cell metabolism. The second, fast filtration, is specifically designed for quenching filamentous micro-organisms. These sampling techniques are combined with an easy sample-preparation procedure and a fast chemical derivatization reaction using methyl chloroformate. This reaction takes place at room temperature, in aqueous medium, and is less prone to matrix effect compared with other derivatizations. This protocol takes an average of 10 d to complete and enables the simultaneous analysis of hundreds of metabolites from the central carbon metabolism (amino and nonamino organic acids, phosphorylated organic acids and fatty acid intermediates) using an in-house MS library and a data analysis pipeline consisting of two free software programs (Automated Mass Deconvolution and Identification System (AMDIS) and R).

  9. [Development of a gas chromatography-mass spectrometry method for the metabolomic study of rice (Oryza sativa L.) grain].

    PubMed

    Zhou, Jia; Wang, Shuangyuan; Chang, Yuwei; Zhao, Yanni; Lu, Xin; Zhao, Chunxia; Xu, Guowang

    2012-10-01

    An analytical strategy for the metabolic profiling of rice grain was developed based on gas chromatography-mass spectrometry (GC-MS). For the purpose of obtaining abundant metabolite information, sample preparation step prior to instrumental analysis is necessary to be optimized. D-optimal experimental design was applied to optimize the extraction solvent. Four solvents, including water, methanol, isopropanol and acetonitrile, and their combinations were evaluated for the extraction efficiency using multivariate statistical analysis (partial least square regression). The count of resolved peaks and the sum of peak areas were taken as the evaluation indexes. Methanol/water (80:20, v/v) mixture was highly efficient for rice metabolites and was selected as the suitable solvent formulation. Then, the analytical characteristics of the method were measured. More than 90% of the metabolites had satisfactory precisions, reproducibilities and stabilities (relative standard deviations (RSDs) < 30%). Most of the detected metabolites (about 88.0% of total peak area) showed good linear responses. With the optimized analytical protocol, 315 metabolites were detected in rice and 86 of which were structurally identified by searching in the NIST 08/Wiley standard mass spectral library, covering carbohydrates, amino acids, organic acids, steroids and so on which showed a broad coverage of metabolite data. The established method is expected to be useful for the metabolomic studies of rice.

  10. An improved, automated whole air sampler and gas chromatography mass spectrometry analysis system for volatile organic compounds in the atmosphere

    NASA Astrophysics Data System (ADS)

    Lerner, Brian M.; Gilman, Jessica B.; Aikin, Kenneth C.; Atlas, Elliot L.; Goldan, Paul D.; Graus, Martin; Hendershot, Roger; Isaacman-VanWertz, Gabriel A.; Koss, Abigail; Kuster, William C.; Lueb, Richard A.; McLaughlin, Richard J.; Peischl, Jeff; Sueper, Donna; Ryerson, Thomas B.; Tokarek, Travis W.; Warneke, Carsten; Yuan, Bin; de Gouw, Joost A.

    2017-01-01

    Volatile organic compounds were quantified during two aircraft-based field campaigns using highly automated, whole air samplers with expedited post-flight analysis via a new custom-built, field-deployable gas chromatography-mass spectrometry instrument. During flight, air samples were pressurized with a stainless steel bellows compressor into electropolished stainless steel canisters. The air samples were analyzed using a novel gas chromatograph system designed specifically for field use which eliminates the need for liquid nitrogen. Instead, a Stirling cooler is used for cryogenic sample pre-concentration at temperatures as low as -165 °C. The analysis system was fully automated on a 20 min cycle to allow for unattended processing of an entire flight of 72 sample canisters within 30 h, thereby reducing typical sample residence times in the canisters to less than 3 days. The new analytical system is capable of quantifying a wide suite of C2 to C10 organic compounds at part-per-trillion sensitivity. This paper describes the sampling and analysis systems, along with the data analysis procedures which include a new peak-fitting software package for rapid chromatographic data reduction. Instrument sensitivities, uncertainties and system artifacts are presented for 35 trace gas species in canister samples. Comparisons of reported mixing ratios from each field campaign with measurements from other instruments are also presented.

  11. [Determination of short chain chlorinated paraffins in leather products by solid phase extraction coupled with gas chromatography-mass spectrometry].

    PubMed

    Zhang, Weiya; Wan, Xin; Li, Lixia; Wang, Chengyun; Jin, Shupei; Xing, Jun

    2014-10-01

    The short chain chlorinated paraffins (SCCPs) are the additives frequently used in the leather production in China, but they have been put into the list of forbidden chemicals issued by European Union recently. In fact, there is not a commonly recognized method for the determination of the SCCPs in the leather products due to the serious matrix interferences from the leather products and the complex chemical structures of the SCCPs. A method of solid phase extraction coupled with gas chromatography-mass spectrometry (SPE-GC-MS) was established for the determination of the SCCPs in the leather products after the optimization of the SPE conditions. It was found that the interferences from the leather products were thor- oughly separated from the analyte of the SCCPs on a home-made solid phase extraction (SPE) column filled with silica packing while eluted with a mixed solvent of n-hexane-methylene chloride (2:1, v/v). With this method, the recoveries for the SCCPs spiked in the real leather samples varied from 90.47% to 99.00% with the relative standard deviations (RSDs) less than 6.7%, and the limits of detection (LODs) were between 0.069 and 0.110 mg/kg. This method is suitable for qualitative and quantitative analysis of SCCPs in the leather products.

  12. Determination of perfluorinated compounds in packaging materials and textiles using pressurized liquid extraction with gas chromatography-mass spectrometry.

    PubMed

    Lv, Gang; Wang, Libing; Liu, Shaocong; Li, Shufen

    2009-03-01

    A simultaneous determination method of trace amounts of perfluorinated compounds, such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in packaging materials and textiles, has been developed, using pressurized liquid extraction (PLE) with gas chromatography-mass spectrometry (GC/MS). The perfluorinated compounds were primarily extracted from the samples by a PLE procedure, in which the parameters were optimized by response surface methodology. The solvent was then removed by blowing nitrogen and a silylation step was carried out with N,N-bis(trimethylsilyl)trifluoroacetamide. The silylated compounds were identified and quantified by GC/MS. The proposed method was applied to determine the PFOA and PFOS in polytetrafluoroethylene packaging materials and textiles, where the detection limits of the two compounds were 1.6 and 13.9 ng mL(-1), respectively. The results showed that the concentrations of PFOA and PFOS in the packaging materials and textiles ranged from 17.5 to 45.9 and 33.7 to 81.3 ng g(-1), respectively.

  13. Determination of seventeen polar/thermolabile pesticides in apples and apricots by liquid chromatography/mass spectrometry.

    PubMed

    Zrostlíková, Jitka; Hajslová, Jana; Kovalczuk, Tomás; Stĕpán, Radim; Poustka, Jan

    2003-01-01

    A simple liquid chromatography/mass spectrometry (LC/MS) approach for the determination of widely used representatives of polar/thermolabile pesticides in fruits was developed and validated. The group of pesticides comprised benzimidazoles and azoles (carbendazim, thiabendazole, imazalil, propiconazole, prochloraz, epoxiconazole, flusilazole, tebuconazole, bitertanol); N-methylcarbamates (carbaryl, carbofuran, methiocarb); and phenylureas and benzoylphenylureas (linuron, diflubenzuron, triflumuron, teflubenzuron, flufenoxuron). Matrixes (apple, apricot) were extracted with acetonitrile and crude extracts were cleaned up by solid-phase extraction (SPE) using either mixed cation exchange or hydrophilic lipophilic balance cartridges. LC separation of pesticides was performed on a reversed-phase column, Discovery C18. Electrospray ionization and ion trap MS/MS detection were applied. For most pesticides, overall recoveries ranged from 75 to 122%, and repeatability (as relative standard deviation) from 5 repetitive determinations of recovery ranged from 3 to 21%. Carbofuran was the only compound for which recovery was not satisfactory due to its loss in the SPE cleanup step. Limits of detection were 0.1-3 microg/kg for benzimidazole and azole fungicides and carbamate insecticides. For urea insecticides, detection limits were slightly higher (3-10 microg/kg).

  14. Ester variability in apple varieties as determined by solid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Young, J Christopher; Chu, C L George; Lu, Xuewen; Zhu, Honghui

    2004-12-29

    Solid-phase microextraction (SPME) with a polydimethylsiloxane fiber coupled with gas chromatography-mass spectrometry (GC-MS) was applied to the study of variability in volatiles released by 13 apple varieties. The relative amounts of 40 esters and alpha-farnesene were determined. Principal component analyses of these results clustered the apples into three groups according to skin color: red, green, and red-green. Total ester contents were highest with the red cluster apples, and the green cluster apples had the highest alpha-farnesene levels. This technology was also applied to the monitoring of changes in volatiles for apples removed from controlled-atmosphere storage with subsequent storage at 4 degrees C and room temperature. Total ester contents increased 25-fold, with the greater increases coming at room temperature, whereas alpha-farnesene levels increased only 5-fold. For apples stored at room temperature, after 11 days, the amount of increase was inversely proportional to the size of the ester: levels of smallest esters (molecular weight 116) increased 12.5-fold, and the largest esters (molecular weight 228) increased approximately 1.3-fold.

  15. Metabolomic investigation of porcine muscle and fatty tissue after Clenbuterol treatment using gas chromatography/mass spectrometry.

    PubMed

    Li, Guanglei; Fu, Yuhua; Han, Xiaosong; Li, Xinyun; Li, Changchun

    2016-07-22

    Clenbuterol is a β-adrenergic agonist used as additive to increase the muscle mass of meat-producing animals. Previous studies were limited to evaluations of animal growth performance and determination of the residues. Several studies have focused on urine samples. Little information about the underlying molecular mechanisms that can explain Clenbuterol metabolism and promote energy repartition in animal muscle and fatty tissue is available. Therefore, this research aims to detect the metabolite variations in muscle and fatty tissue acquired from Chinese pigs fed with Clenbuterol using gas chromatography/mass spectrometry (GC/MS). Ten two-month old Enshi black pigs were fed under the same condition; five of which were fed with basic ration containing Clenbuterol for one month, whereas the other five pigs were fed only with basic ration. Muscle and fatty tissue were subjected to metabolomics analysis using GC/MS. Differences in metabolomic profiles between the two groups were characterized by multivariate statistical analysis. The muscle samples showed that 15 metabolites were significantly different in the Clenbuterol-treated group compared with the control group; 13 potential biomarkers were found in the fatty tissue. Most of the metabolites were associated with fatty acid metabolism and amino acid metabolism. Glycerol, phenylalanine, and leucine were the common metabolites between the muscle and fatty tissue. These metabolites may provide a new clue that contributes to the understanding of the energy reassignment induced by Clenbuterol.

  16. Assessment of stability of ketamine-xylazine preparations with or without acepromazine using high performance liquid chromatography-mass spectrometry

    PubMed Central

    Dodelet-Devillers, Aurore; Zullian, Chiara; Vachon, Pascal; Beaudry, Francis

    2016-01-01

    The objective of this study was to evaluate the stability of 3 distinct preparations of ketamine and xylazine, with or without acepromazine, stored at room temperature or at 4°C for 1, 2, and 3 mo. Drug concentrations were compared to fresh solutions, using a high performance liquid chromatography-mass spectrometry/selected-ion monitoring (HPLC-MS/SIM) assay. The concentrations of ketamine and xylazine, diluted in physiological saline, did not change over time at room temperature or at 4°C. However, acepromazine concentrations decreased over time when stored at room temperature. In contrast, undiluted ketamine-xylazine preparations gradually decreased in concentration when stored at room temperature. All of the drug concentrations remained above 90% of their original concentration when stored at 4°C. In conclusion, when diluted in physiological saline, ketamine-xylazine cocktails can be stored for 3 mo, whereas undiluted cocktails can lose efficacy over 3 mo at room temperature. Storage at 4°C could preserve drug stability. PMID:26733737

  17. Gas Chromatography-Mass Spectrometry Analysis of Ulva fasciata (Green Seaweed) Extract and Evaluation of Its Cytoprotective and Antigenotoxic Effects.

    PubMed

    Rodeiro, Idania; Olguín, Sitlali; Santes, Rebeca; Herrera, José A; Pérez, Carlos L; Mangas, Raisa; Hernández, Yasnay; Fernández, Gisselle; Hernández, Ivones; Hernández-Ojeda, Sandra; Camacho-Carranza, Rafael; Valencia-Olvera, Ana; Espinosa-Aguirre, Jesús Javier

    2015-01-01

    The chemical composition and biological properties of Ulva fasciata aqueous-ethanolic extract were examined. Five components were identified in one fraction prepared from the extract by gas chromatography-mass spectrometry, and palmitic acid and its ethyl ester accounted for 76% of the total identified components. Furthermore, we assessed the extract's antioxidant properties by using the DPPH, ABTS, and lipid peroxidation assays and found that the extract had a moderate scavenging effect. In an experiment involving preexposition and coexposition of the extract (1-500 µg/mL) and benzo[a]pyrene (BP), the extract was found to be nontoxic to C9 cells in culture and to inhibit the cytotoxicity induced by BP. As BP is biotransformed by CYP1A and CYP2B subfamilies, we explored the possible interaction of the extract with these enzymes. The extract (25-50 µg/mL) inhibited CYP1A1 activity in rat liver microsomes. Analysis of the inhibition kinetics revealed a mixed-type inhibitory effect on CYP1A1 supersome. The effects of the extract on BP-induced DNA damage and hepatic CYP activity in mice were also investigated. Micronuclei induction by BP and liver CYP1A1/2 activities significantly decreased in animals treated with the extract. The results suggest that Ulva fasciata aqueous-ethanolic extract inhibits BP bioactivation and it may be a potential chemopreventive agent.

  18. Simultaneous determination of cannabidiol, cannabinol, and delta9-tetrahydrocannabinol in human hair by gas chromatography-mass spectrometry.

    PubMed

    Kim, Jin Young; Suh, Sung Ill; In, Moon Kyo; Paeng, Ki-Jung; Chung, Bong Chul

    2005-09-01

    An analytical method was developed for evaluating the cannabidiol (CBD), cannabinol (CBN), and delta9-tetrahydrocannabinol (delta9-THC) level in human hair using gas chromatography-mass spectrometry (GC-MS). Hair samples (50 mg) were washed with isopropyl alcohol and cut into small fragments (< 1 mm). After adding a deuterated internal standard, the hair samples were incubated in 1.0 M NaOH for 10 min at 95 degrees C. The analytes from the resulting hydrolyzed samples were extracted using a mixture of n-hexane-ethyl acetate (75:25, v/v). The extracts were then evaporated, derivatized, and injected into the GC-MS. The recovery ranges of CBD, CBN, and delta9-THC at three concentration levels were 37.9-94.5% with good correlation coefficients (r2 >0.9989). The intra-day precision and accuracy ranged from -9.4% to 17.7%, and the inter-day precision and accuracy ranged from -15.5% to 14.5%, respectively. The limits of detection (LOD) for CBD, CBN, and delta9-THC were 0.005, 0.002, and 0.006 ng/mg, respectively. The applicability of this method of analyzing the hair samples from cannabis abusers was demonstrated.

  19. Simultaneous assay of isotopic enrichment and concentration of guanidinoacetate and creatine by gas chromatography-mass spectrometry.

    PubMed

    Kasumov, Takhar; Gruca, Lourdes L; Dasarathy, Srinivasan; Kalhan, Satish C

    2009-12-01

    A gas chromatography-mass spectrometry (GC-MS) method for the simultaneous measurement of isotopic enrichment and concentration of guanidinoacetate (GAA) and creatine in plasma sample for kinetic studies is reported. The method, based on preparation of the bis(trifluoromethyl)pyrimidine methyl ester derivatives of GAA and creatine, is robust and sensitive. The lowest measurable m(1) and m(3) enrichment for GAA and creatine, respectively, was 0.3%. The calibration curves for measurements of concentration were linear over ranges of 0.5 to 250microM GAA and 2 to 500microM for creatine. The method was reliable for inter- and intraassay precision, accuracy, and linearity. The technique was applied in a healthy adult to determine the in vivo fractional synthesis rate of creatine using primed-constant rate infusion of [1-(13)C]glycine. It was found that isotopic enrichment of GAA reached a plateau by 30min of infusion of [1-(13)C]glycine, indicating either a small pool size or a rapid turnover rate (or both) of GAA. In contrast, the tracer appearance in creatine was slow (slope=0.00097), suggesting a large pool size and a slow rate of synthesis of creatine. This method can be used to estimate the rate of synthesis of creatine in vivo in human and animal studies.

  20. Rapid monitoring of sulfur mustard degradation in solution by headspace solid-phase microextraction sampling and gas chromatography mass spectrometry.

    PubMed

    Creek, Jo-Anne M; McAnoy, Andrew M; Brinkworth, Craig S

    2010-12-15

    A method using headspace solid-phase microextraction (HS-SPME) followed by gas chromatography/mass spectrometry (GC/MS) analysis has been developed to gain insight into the degradation of the chemical warfare agent sulfur mustard in solution. Specifically, the described approach simplifies the sample preparation for GC/MS analysis to provide a rapid determination of changes in sulfur mustard abundance. These results were found to be consistent with those obtained using liquid-liquid extraction (LLE) GC/MS. The utility of the described approach was further demonstrated by the investigation of the degradation process in a complex matrix with surfactant added to assist solvation of sulfur mustard. A more rapid reduction in sulfur mustard abundance was observed using the HS-SPME approach with surfactant present and was similar to results from LLE experiments. Significantly, this study demonstrates that HS-SPME can simplify the sample preparation for GC/MS analysis to monitor changes in sulfur mustard abundance in solution more rapidly, and with less solvent and reagent usage than LLE.