The potential of Isotope Ratio Mass Spectrometry (IRMS) and gas chromatography-IRMS analysis of triacetone triperoxide in forensic explosives investigations

NARCIS (Netherlands)

Bezemer, K.D.B.; Koeberg, M.; Heijden, A.E.D.M. van der; Driel, C.A. va; Blaga, C.; Bruinsma, J.; Asten, A.C. van

2016-01-01

Studying links between triacetone triperoxide (TATP) samples from crime scenes and suspects can assist in criminal investigations. Isotope ratio mass spectrometry (IRMS) and gas chromatography (GC)-IRMS were used to measure the isotopic compositions of TATP and its precursors acetone and hydrogen

Analysis of trace levels of impurities and hydrogen isotopes in helium purge gas using gas chromatography for tritium extraction system of an Indian lead lithium ceramic breeder test blanket module.

Science.gov (United States)

Devi, V Gayathri; Sircar, Amit; Yadav, Deepak; Parmar, Jayraj

2018-01-12

In the fusion fuel cycle, the accurate analysis and understanding of the chemical composition of any gas mixture is of great importance for the efficient design of a tritium extraction and purification system or any tritium handling system. Methods like laser Raman spectroscopy and gas chromatography with thermal conductivity detector have been considered for hydrogen isotopes analyses in fuel cycles. Gas chromatography with a cryogenic separation column has been used for the analysis of hydrogen isotopes gas mixtures in general due to its high reliability and ease of operation. Hydrogen isotopes gas mixture analysis with cryogenic columns has been reported earlier using different column materials for percentage level composition. In the present work, trace levels of hydrogen isotopes (∼100 ppm of H 2 and D 2 ) have been analyzed with a Zeolite 5A and a modified γ-Al 2 O 3 column. Impurities in He gas (∼10 ppm of H 2 , O 2 , and N 2 ) have been analyzed using a Zeolite 13-X column. Gas chromatography with discharge ionization detection has been utilized for this purpose. The results of these experiments suggest that the columns developed were able to separate ppm levels of the desired components with a small response time (<6 min) and good resolution in both cases. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Measurement of Muscle Protein Fractional Synthetic Rate by Capillary Gas Chromatography/Combustion Isotope Ratio Mass Spectrometry

OpenAIRE

Yarasheski, Kevin E.; Smith, Kenneth; Rennie, Michael J.; Bier, Dennis M.

1992-01-01

The measurement of skeletal muscle protein fractional synthetic rate using an infusion of (1-13C)leucine and measuring the isotopic abundance of the tracer in skeletal muscle protein by preparative gas chromatography (GC)/ninhydrin isotope ratio mass spectrometry (IRMS) is laborious and subject to errors owing to contamination by 12C. The purpose of this study was to compare muscle (13C)leucine enrichment measured with the conventional preparative GC/ninhydrin IRMS approach to a new, continuo...

Serum/plasma methylmercury determination by isotope dilution gas chromatography-inductively coupled plasma mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Baxter, Douglas C., E-mail: douglas.baxter@alsglobal.com [ALS Scandinavia AB, Aurorum 10, 977 75 Lulea (Sweden); Faarinen, Mikko [ALS Scandinavia AB, Aurorum 10, 977 75 Lulea (Sweden); Osterlund, Helene; Rodushkin, Ilia [ALS Scandinavia AB, Aurorum 10, 977 75 Lulea (Sweden); Division of Geosciences, Lulea University of Technology, 977 87 Lulea (Sweden); Christensen, Morten [ALS Scandinavia AB, Maskinvaegen 2, 183 53 Taeby (Sweden)

2011-09-09

Highlights: {center_dot} We determine methylmercury in serum and plasma using isotope dilution calibration. {center_dot} Separation by gas chromatography and detection by inductively coupled plasma mass spectrometry. {center_dot} Data for 50 specimens provides first reference range for methylmercury in serum. {center_dot} Serum samples shown to be stable for 11 months in refrigerator. - Abstract: A method for the determination of methylmercury in plasma and serum samples was developed. The method uses isotope dilution with {sup 198}Hg-labeled methylmercury, extraction into dichloromethane, back-extraction into water, aqueous-phase ethylation, purge and trap collection, thermal desorption, separation by gas chromatography, and mercury isotope specific detection by inductively coupled plasma mass spectrometry. By spiking 2 mL sample with 1.2 ng tracer, measurements in a concentration interval of (0.007-2.9) {mu}g L{sup -1} could be performed with uncertainty amplification factors <2. A limit of quantification of 0.03 {mu}g L{sup -1} was estimated at 10 times the standard deviation of concentrations measured in preparation blanks. Within- and between-run relative standard deviations were <10% at added concentration levels of 0.14 {mu}g L{sup -1}, 0.35 {mu}g L{sup -1} and 2.8 {mu}g L{sup -1}, with recoveries in the range 82-110%. Application of the method to 50 plasma/serum samples yielded a median (mean; range) concentration of methylmercury of 0.081 (0.091; <0.03-0.19) {mu}g L{sup -1}. This is the first time methylmercury has been directly measured in this kind of specimen, and is therefore the first estimate of a reference range.

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

International Nuclear Information System (INIS)

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

1990-01-01

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

Isotopic separation by ion chromatography

International Nuclear Information System (INIS)

Albert, M.G.; Barre, Y.; Neige, R.

1994-01-01

The isotopic exchange reaction and the isotopic separation factor are first recalled; the principles of ion chromatography applied to lithium isotope separation are then reviewed (displacement chromatography) and the process is modelled in the view of dimensioning and optimizing the industrial process; the various dimensioning parameters are the isotopic separation factor, the isotopic exchange kinetics and the material flow rate. Effects of the resin type and structure are presented. Dimensioning is also affected by physico-chemical and hydraulic parameters. Industrial implementation features are also discussed. 1 fig., 1 tab., 5 refs

Simultaneous determination of creatinine and creatine in human serum by double-spike isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-mass spectrometry (GC-MS).

Science.gov (United States)

Fernández-Fernández, Mario; Rodríguez-González, Pablo; Añón Álvarez, M Elena; Rodríguez, Felix; Menéndez, Francisco V Álvarez; García Alonso, J Ignacio

2015-04-07

This work describes the first multiple spiking isotope dilution procedure for organic compounds using (13)C labeling. A double-spiking isotope dilution method capable of correcting and quantifying the creatine-creatinine interconversion occurring during the analytical determination of both compounds in human serum is presented. The determination of serum creatinine may be affected by the interconversion between creatine and creatinine during sample preparation or by inefficient chemical separation of those compounds by solid phase extraction (SPE). The methodology is based on the use differently labeled (13)C analogues ((13)C1-creatinine and (13)C2-creatine), the measurement of the isotopic distribution of creatine and creatinine by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and the application of multiple linear regression. Five different lyophilized serum-based controls and two certified human serum reference materials (ERM-DA252a and ERM-DA253a) were analyzed to evaluate the accuracy and precision of the proposed double-spike LC-MS/MS method. The methodology was applied to study the creatine-creatinine interconversion during LC-MS/MS and gas chromatography-mass spectrometry (GC-MS) analyses and the separation efficiency of the SPE step required in the traditional gas chromatography-isotope dilution mass spectrometry (GC-IDMS) reference methods employed for the determination of serum creatinine. The analysis of real serum samples by GC-MS showed that creatine-creatinine separation by SPE can be a nonquantitative step that may induce creatinine overestimations up to 28% in samples containing high amounts of creatine. Also, a detectable conversion of creatine into creatinine was observed during sample preparation for LC-MS/MS. The developed double-spike LC-MS/MS improves the current state of the art for the determination of creatinine in human serum by isotope dilution mass spectrometry (IDMS), because corrections are made for all the possible errors

Compound-Specific Chlorine Isotope Analysis of Tetrachloromethane and Trichloromethane by Gas Chromatography-Isotope Ratio Mass Spectrometry vs Gas Chromatography-Quadrupole Mass Spectrometry: Method Development and Evaluation of Precision and Trueness.

Science.gov (United States)

Heckel, Benjamin; Rodríguez-Fernández, Diana; Torrentó, Clara; Meyer, Armin; Palau, Jordi; Domènech, Cristina; Rosell, Mònica; Soler, Albert; Hunkeler, Daniel; Elsner, Martin

2017-03-21

Compound-specific chlorine isotope analysis of tetrachloromethane (CCl 4 ) and trichloromethane (CHCl 3 ) was explored by both, gas chromatography-isotope ratio mass spectrometry (GC-IRMS) and GC-quadrupole MS (GC-qMS), where GC-qMS was validated in an interlaboratory comparison between Munich and Neuchâtel with the same type of commercial GC-qMS instrument. GC-IRMS measurements analyzed CCl isotopologue ions, whereas GC-qMS analyzed the isotopologue ions CCl 3 , CCl 2 , CCl (of CCl 4 ) and CHCl 3 , CHCl 2 , CHCl (of CHCl 3 ), respectively. Lowest amount dependence (good linearity) was obtained (i) in H-containing fragment ions where interference of 35 Cl- to 37 Cl-containing ions was avoided; (ii) with tuning parameters favoring one predominant rather than multiple fragment ions in the mass spectra. Optimized GC-qMS parameters (dwell time 70 ms, 2 most abundant ions) resulted in standard deviations of 0.2‰ (CHCl 3 ) and 0.4‰ (CCl 4 ), which are only about twice as large as 0.1‰ and 0.2‰ for GC-IRMS. To compare also the trueness of both methods and laboratories, samples from CCl 4 and CHCl 3 degradation experiments were analyzed and calibrated against isotopically different reference standards for both CCl 4 and CHCl 3 (two of each). Excellent agreement confirms that true results can be obtained by both methods provided that a consistent set of isotopically characterized reference materials is used.

Analysis of [U-13C6]glucose in human plasma using liquid chromatography/isotope ratio mass spectrometry compared with two other mass spectrometry techniques

NARCIS (Netherlands)

Schierbeek, H.; Moerdijk-Poortvliet, T.C.W.; van den Akker, C.H.P.; te Braake, F.W.J.; Boschker, H.T.S.; van Goudoever, J.B.

2009-01-01

The use of stable isotope labelled glucose provides insight into glucose metabolism. The 13C-isotopic enrichment of glucose is usually measured by gas chromatography/mass spectrometry (GC/MS) or gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). However, in both techniques

Liquid and gas chromatography coupled to isotope ratio mass spectrometry for the determination of 13C-valine isotopic ratios in complex biological samples.

Science.gov (United States)

Godin, Jean-Philippe; Breuillé, Denis; Obled, Christiane; Papet, Isabelle; Schierbeek, Henk; Hopfgartner, Gérard; Fay, Laurent-Bernard

2008-10-01

On-line gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) is commonly used to measure isotopic ratios at natural abundance as well as for tracer studies in nutritional and medical research. However, high-precision (13)C isotopic enrichment can also be measured by liquid chromatography-isotope ratio mass spectrometry (LC-IRMS). Indeed, LC-IRMS can be used, as shown by the new method reported here, to obtain a baseline separation and to measure (13)C isotopic enrichment of underivatised amino acids (Asp, Thr-Ser, Glu, Pro, Gly, Ala, Cys and Val). In case of Val, at natural abundance, the SD(delta(13)C) reported with this method was found to be below 1 per thousand . Another key feature of the new LC-IRMS method reported in this paper is the comparison of the LC-IRMS approach with the conventional GC-C-IRMS determination. To perform this comparative study, isotopic enrichments were measured from underivatised Val and its N(O, S)-ethoxycarbonyl ethyl ester derivative. Between 0.0 and 1.0 molar percent excess (MPE) (delta(13)C= -12.3 to 150.8 per thousand), the calculated root-mean-square (rms) of SD was 0.38 and 0.46 per thousand and the calculated rms of accuracy was 0.023 and 0.005 MPE, respectively, for GC-C-IRMS and LC-IRMS. Both systems measured accurately low isotopic enrichments (0.002 atom percent excess (APE)) with an SD (APE) of 0.0004. To correlate the relative (delta(13)C) and absolute (atom%, APE and MPE) isotopic enrichment of Val measured by the GC-C-IRMS and LC-IRMS devices, mathematical equations showing the slope and intercept of the curves were established and validated with experimental data between 0.0 to 2.3 MPE. Finally, both GC-C-IRMS and LC-IRMS instruments were also used to assess isotopic enrichment of protein-bound (13)C-Val in tibial epiphysis in a tracer study performed in rats. Isotopic enrichments measured by LC-IRMS and GC-C-IRMS were not statistically different (p>0.05). The results of this work indicate that

Using Gas Chromatography/Isotope Ratio Mass Spectrometry to Determine the Fractionation Factor for H2 Production by Hydrogenases

International Nuclear Information System (INIS)

Yang, Hui; Ghandi, H.; Shi, Liang; Kreuzer, Helen W.; Ostrom, Nathaniel; Hegg, Eric L.

2012-01-01

Hydrogenases catalyze the reversible formation of H2, and they are key enzymes in the biological cycling of H2. H isotopes should be a very useful tool in quantifying proton trafficking in biological H2 production processes, but there are several obstacles that have thus far limited the use of this tool. In this manuscript, we describe a new method that overcomes some of these barriers and is specifically designed to measure isotopic fractionation during enzyme-catalyzed H2 evolution. A key feature of this technique is that purified hydrogenases are employed, allowing precise control over the reaction conditions and therefore a high level of precision. A custom-designed high-throughput gas chromatography-isotope ratio mass spectrometer is employed to measure the isotope ratio of the H2. Using this method, we determined that the fractionation factor of H2 production by the (NiFe)-hydrogenase from Desulfivibrio fructosovran is 0.27. This result indicates that, as expected, protons are highly favored over deuterons during H2 evolution. Potential applications of this new method are discussed.

Isotope Ratio Monitoring Gas Chromatography Mass Spectrometry (IRM-GCMS)

International Nuclear Information System (INIS)

Freeman, K.H.; Ricci, S.A.; Studley, A.; Hayes, J.M.

1989-01-01

On Earth, the C-13 content of organic compounds is depleted by roughly 13 to 23 permil from atmospheric carbon dioxide. This difference is largely due to isotope effects associated with the fixation of inorganic carbon by photosynthetic organisms. If life once existed on Mars, then it is reasonable to expect to observe a similar fractionation. Although the strongly oxidizing conditions on the surface of Mars make preservation of ancient organic material unlikely, carbon-isotope evidence for the existence of life on Mars may still be preserved. Carbon depleted in C-13 could be preserved either in organic compounds within buried sediments, or in carbonate minerals produced by the oxidation of organic material. A technique is introduced for rapid and precise measurement of the C-13 contents of individual organic compounds. A gas chromatograph is coupled to an isotope-ratio mass spectrometer through a combustion interface, enabling on-line isotopic analysis of isolated compounds. The isotope ratios are determined by integration of ion currents over the course of each chromatographic peak. Software incorporates automatic peak determination, corrections for background, and deconvolution of overlapped peaks. Overall performance of the instrument was evaluated by the analysis of a mixture of high purity n-alkanes of know isotopic composition. Isotopic values measured via IRM-GCMS averaged withing 0.55 permil of their conventionally measured values

Applications of the gas chromatography in the nuclear science and technology

International Nuclear Information System (INIS)

Gasco Sanchez, L.

1972-01-01

This paper is a review on the applications of the gas chromatography in the nuclear science and technology published up to December 1971. Its contents has been classified under the following heads; I) Radiogaschromatography, II) Isotope separation, III) Preparation of labelled molecules, IV) Nuclear fuel cycle, V) Nuclear reactor technology, VI) Irradiation chemistry, VIl) Separation of me tal compounds in gas phase, VIII) Applications of the gas chromatography carried out at the Junta de Energia Nuclear, Spain. Arapter VIII only includes the investigations carried out from January 1969 to December 1971. Previous investigations in this field has been published elsewhere. (Author)

delta 13C analyses of vegetable oil fatty acid components, determined by gas chromatography--combustion--isotope ratio mass spectrometry, after saponification or regiospecific hydrolysis.

Science.gov (United States)

Woodbury, S E; Evershed, R P; Rossell, J B

1998-05-01

The delta 13C values of the major fatty acids of several different commercially important vegetable oils were measured by gas chromatography--combustion--isotope ratio mass spectrometry. The delta 13C values obtained were found to fall into two distinct groups, representing the C3 and C4 plants classes from which the oils were derived. The delta 13C values of the oils were measured by continuous flow elemental isotope ratio mass spectrometry and were found to be similar to their fatty acids, with slight differences between individual fatty acids. Investigations were then made into the influence on the delta 13C values of fatty acids of the position occupied on the glycerol backbone. Pancreatic lipase was employed to selectively hydrolyse fatty acids from the 1- and 3-positions with the progress of the reaction being followed by high-temperature gas chromatography in order to determine the optimum incubation time. The 2-monoacylglycerols were then isolated by thin-layer chromatography and fatty acid methyl esters prepared. The delta 13C values obtained indicate that fatty acids from any position on the glycerol backbone are isotopically identical. Thus, whilst quantification of fatty acid composition at the 2-position and measurement of delta 13C values of oils and their major fatty acids are useful criteria in edible oil purity assessment, measurement of delta 13C values of fatty acids from the 2-position does not assist with oil purity assignments.

The Potential of Isotope Ratio Mass Spectrometry (IRMS) and Gas Chromatography-IRMS Analysis of Triacetone Triperoxide in Forensic Explosives Investigations.

Science.gov (United States)

Bezemer, Karlijn D B; Koeberg, Mattijs; van der Heijden, Antoine E D M; van Driel, Chris A; Blaga, Cornelia; Bruinsma, Jildert; van Asten, Arian C

2016-09-01

Studying links between triacetone triperoxide (TATP) samples from crime scenes and suspects can assist in criminal investigations. Isotope ratio mass spectrometry (IRMS) and gas chromatography (GC)-IRMS were used to measure the isotopic compositions of TATP and its precursors acetone and hydrogen peroxide. In total, 31 TATP samples were synthesized with different raw material combinations and reaction conditions. For carbon, a good differentiation and a linear relationship were observed for acetone-TATP combinations. The extent of negative (δ(13) C) fractionation depended on the reaction yield. Limited enrichment was observed for the hydrogen isotope (δ(2) H) values of the TATP samples probably due to a constant exchange of hydrogen atoms in aqueous solution. For oxygen (δ(18) O), the small isotopic range and excess of water in hydrogen peroxide resulted in poor differentiation. GC-IRMS and IRMS data were comparable except for one TATP sample prepared with high acid concentration demonstrating the potential of compound-specific isotope analysis. Carbon IRMS has practical use in forensic TATP investigations. © 2016 American Academy of Forensic Sciences.

Isotopic fractionation of fentanyl and its deuterated analogues by capillary gas chromatography

International Nuclear Information System (INIS)

Sera, Shoji; Goromaru, Tsuyoshi

1997-01-01

Isotopic fractionation of fentanyl (FT) and its deuterated analogues by gas chromatography using capillary columns (CBP1 and CBP5) has been investigated. Seven kinds of analogues were labeled with 5 to 19 deuterium atoms at the anilino, propionyl and/or phenylethyl group of FT. The retention times of deuterated FT in CBP1 and CBP5 columns are inversely proportional to the number of labeled deuterium atoms in the molecule. The difference in free enegy changes (ΔΔG) had a linear relationship with the number of labeled deuterium atoms, except for labeling at anilino and phenylethyl group. The contribution of a deuterium atom to the ΔΔG value was estimated to be 1.13 cal/mol in CBP1 and 1.40 cal/mol in CBP5, respectively. While, its contribution in the propiony group was 2.84 cal/mol in CBP1 and 2.48 cal/mol in CBP5, respectively. An important factor in separation by GC may differences in interactions between the stationary phase of the column with the three dimensional protrusive moiety in the molecule. (author)

Isotopic fractionation of fentanyl and its deuterated analogues by capillary gas chromatography

Energy Technology Data Exchange (ETDEWEB)

Sera, Shoji; Goromaru, Tsuyoshi [Fukuyama Univ., Hiroshima (Japan)

1997-12-01

Isotopic fractionation of fentanyl (FT) and its deuterated analogues by gas chromatography using capillary columns (CBP1 and CBP5) has been investigated. Seven kinds of analogues were labeled with 5 to 19 deuterium atoms at the anilino, propionyl and/or phenylethyl group of FT. The retention times of deuterated FT in CBP1 and CBP5 columns are inversely proportional to the number of labeled deuterium atoms in the molecule. The difference in free enegy changes ({Delta}{Delta}G) had a linear relationship with the number of labeled deuterium atoms, except for labeling at anilino and phenylethyl group. The contribution of a deuterium atom to the {Delta}{Delta}G value was estimated to be 1.13 cal/mol in CBP1 and 1.40 cal/mol in CBP5, respectively. While, its contribution in the propiony group was 2.84 cal/mol in CBP1 and 2.48 cal/mol in CBP5, respectively. An important factor in separation by GC may differences in interactions between the stationary phase of the column with the three dimensional protrusive moiety in the molecule. (author)

Adsorption gas chromatography with 150-ms {sup 216}Po

Energy Technology Data Exchange (ETDEWEB)

Vogt, A [Bern Univ. (Switzerland); Gaeggeler, H W; Tuerler, A [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

1997-09-01

A gas chromatography apparatus was developed, which allows experiments with volatile radionuclides having shorter half-lives than one second. This apparatus was tested with the 150-ms isotope {sup 216}Po. Experimental data were compared with a Monte Carlo model to determine the adsorption enthalpy {Delta}H{sub a}. (author) 2 figs., 2 refs.

Review: Current applications and challenges for liquid chromatography coupled to isotope ratio mass spectrometry (LC/IRMS).

Science.gov (United States)

Godin, Jean-Philippe; McCullagh, James S O

2011-10-30

High-precision isotope analysis is recognized as an essential research tool in many fields of study. Until recently, continuous flow isotope ratio mass spectrometry (CF-IRMS) was available via an elemental analyzer or a gas chromatography inlet system for compound-specific analysis of light stable isotopes. In 2004, however, an interface that coupled liquid chromatography with IRMS (LC/IRMS) became commercially available for the first time. This brought the capability for new areas of application, in particular enabling compound-specific δ(13)C analysis of non-volatile, aqueous soluble, compounds from complex mixtures. The interface design brought with it several analytical constraints, however, in particular a lack of compatibility with certain types of chromatography as well as limited flow rates and mobile phase compositions. Routine LC/IRMS methods have, however, been established for measuring the δ(13)C isotopic ratios of underivatized individual compounds for application in archeology, nutrition and physiology, geochemistry, hydrology, soil science and food authenticity. Seven years after its introduction, we review the technical advances and constraints, methodological developments and new applications of liquid chromatography coupled to isotope ratio mass spectrometry. Copyright © 2011 John Wiley & Sons, Ltd.

Simultaneous stable carbon isotopic analysis of wine glycerol and ethanol by liquid chromatography coupled to isotope ratio mass spectrometry.

Science.gov (United States)

Cabañero, Ana I; Recio, Jose L; Rupérez, Mercedes

2010-01-27

A novel procedure was established for the simultaneous characterization of wine glycerol and ethanol (13)C/(12)C isotope ratio, using liquid chromatography/isotope ratio mass spectrometry (LC-IRMS). Several parameters influencing separation of glycerol and ethanol from wine matrix were optimized. Results obtained for 35 Spanish samples exposed no significant differences and very strong correlations (r = 0.99) between the glycerol (13)C/(12)C ratios obtained by an alternative method (gas chromatography/isotope ratio mass spectrometry) and the proposed new methodology, and between the ethanol (13)C/(12)C ratios obtained by the official method (elemental analyzer/isotope ratio mass spectrometry) and the proposed new methodology. The accuracy of the proposed method varied from 0.01 to 0.19 per thousand, and the analytical precision was better than 0.25 per thousand. The new developed LC-IRMS method it is the first isotopic method that allows (13)C/(12)C determination of both analytes in the same run directly from a liquid sample with no previous glycerol or ethanol isolation, overcoming technical difficulties associated with complex sample treatment and improving in terms of simplicity and speed.

Compound-specific isotope analysis of light elements using gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) and its application to geochemistry

International Nuclear Information System (INIS)

Naraoka, Hiroshi; Yamada, Keita; Matsumoto, Kohei; Ishiwatari, Ryoshi

1997-01-01

Compound-specific isotope analysis has been developed recently using gas chromatography/combustion/mass spectrometry (GC/C/IRMS). This paper summarizes principles and progress of GC/C/IRMS, and reviews recent some important works using this new method. GC/C/IRMS is a novel tool for (1) biomarker analysis in sediments and living matter, (2) paleoenvironment analysis including reconstruction of ancient biogeochemical processes, (3) geochemical cycle study of organic compounds in a terrestrial-marine system, (4) evaluation of maturity and diagenesis of organic matter including petroleum formation, (5) ecological analysis, (6) evaluation of anthropologenic pollution in environment, (7) detection of extraterrestrial organic compounds and the formation mechanism study, (8) tracer studies in environment. (author)

Gas Phase Chromatography of some Group 4, 5, and 6 Halides

Energy Technology Data Exchange (ETDEWEB)

Sylwester, Eric Robert [Univ. of California, Berkeley, CA (United States)

1998-10-01

Gas phase chromatography using The Heavy Element Volatility Instrument (HEVI) and the On Line Gas Apparatus (OLGA III) was used to determine volatilities of ZrBr₄, HfBr₄, RfBr₄, NbBr₅, TaOBr₃, HaCl₅, WBr₆, FrBr, and BiBr₃. Short-lived isotopes of Zr, Hf, Rf, Nb, Ta, Ha, W, and Bi were produced via compound nucleus reactions at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory and transported to the experimental apparatus using a He gas transport system. The isotopes were halogenated, separated from the other reaction products, and their volatilities determined by isothermal gas phase chromatography. Adsorption Enthalpy (ΔH_a) values for these compounds were calculated using a Monte Carlo simulation program modeling the gas phase chromatography column. All bromides showed lower volatility than molecules of similar molecular structures formed as chlorides, but followed similar trends by central element. Tantalum was observed to form the oxybromide, analogous to the formation of the oxychloride under the same conditions. For the group 4 elements, the following order in volatility and ΔH_a was observed: RfBr₄ > ZrBr₄ > HfBr₄. The ΔH_a values determined for the group 4, 5, and 6 halides are in general agreement with other experimental data and theoretical predictions. Preliminary experiments were performed on Me-bromides. A new measurement of the half-life of ²⁶¹Rf was performed. ²⁶¹Rf was produced via the ²⁴⁸Cm(¹⁸O, 5n) reaction and observed with a half-life of 74_-6⁺⁷ seconds, in excellent agreement with the previous measurement of 78_-6⁺¹¹ seconds. We recommend a new half-life of 75±7 seconds for ²⁶¹Rf based on these two measurements. Preliminary studies in transforming HEVI from an isothermal (constant

Dual element ((15)N/(14)N, (13)C/(12)C) isotope analysis of glyphosate and AMPA by derivatization-gas chromatography isotope ratio mass spectrometry (GC/IRMS) combined with LC/IRMS.

Science.gov (United States)

Mogusu, Emmanuel O; Wolbert, J Benjamin; Kujawinski, Dorothea M; Jochmann, Maik A; Elsner, Martin

2015-07-01

To assess sources and degradation of the herbicide glyphosate [N-(phosphonomethyl) glycine] and its metabolite AMPA (aminomethylphosphonic acid), concentration measurements are often inconclusive and even (13)C/(12)C analysis alone may give limited information. To advance isotope ratio analysis of an additional element, we present compound-specific (15)N/(14)N analysis of glyphosate and AMPA by a two step derivatization in combination with gas chromatography/isotope ratio mass spectrometry (GC/IRMS). The N-H group was derivatized with isopropyl chloroformate (iso-PCF), and remaining acidic groups were subsequently methylated with trimethylsilyldiazomethane (TMSD). Iso-PCF treatment at pH 10 indicated decomposition of the derivative. At pH 10, and with an excess of iso-PCF by 10-24, greatest yields and accurate (15)N/(14)N ratios were obtained (deviation from elemental analyzer-IRMS: -0.2 ± 0.9% for glyphosate; -0.4 ± 0.7% for AMPA). Limits for accurate δ(15)N analysis of glyphosate and AMPA were 150 and 250 ng injected, respectively. A combination of δ(15)N and δ(13)C analysis by liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) (1) enabled an improved distinction of commercial glyphosate products and (2) showed that glyphosate isotope values during degradation by MnO2 clearly fell outside the commercial product range. This highlights the potential of combined carbon and nitrogen isotopes analysis to trace sources and degradation of glyphosate.

[Determination of endogenous agmatine in rat plasma by isotope dilution-gas chromatography-mass spectrometry].

Science.gov (United States)

Qiu, Zhongli; Lin, Ying; Xiong, Zhili; Xie, Jianwei

2014-07-01

A method for the determination of endogenous agmatine in rat plasma was developed by isotope dilution-gas chromatography-negative chemical ionization mass spectrometry (GC-NCI/MS). The plasma samples were analyzed after protein precipitation, evaporation, derivatization by hexafluoroacetone (HFAA), and clean-up on a Florisil SPE column. The GC-MS analysis utilized stable isotope d8-agmatine as internal standard. The samples after treatme were tested by negative chemical ionization with selected ion monitoring (SIM) which was set at m/z 492 (molecular ion of agmatine) and m/z 500 (molecular ion of internal standard). The limit of detection (LOD) of agmatine standard solution was 0.005 7 ng/mL. The calibration curve of the agmatine spiked in rat plasma showed a good linear relationship at the range of 1.14-57.0 ng/mL (r = 0.997). The recoveries of agmatine spiked in rat plasma ranged from 92.3% to 109.8%. Inter-day and intra-day precisions were less than 15%. The average concentration level of agmatine in rat plasma was (22 +/- 9) ng/mL, and there was no significant difference between male and female SD rats (p > 0.05). The method is high sensitive and specific, and can be used for the determination of endogenous agmatine in plasma. It provides a strong support for the subsequent research of agmatine.

Fractionation of lithium isotopes in cation-exchange chromatography

International Nuclear Information System (INIS)

Oi, Takao; Kawada, Kazuhiko; Kakihana, Hidetake; Hosoe, Morikazu

1991-01-01

Various methods for lithium isotope separation have been developed, and their applicability to large-scale enriched lithium isotope production has been assessed. Ion-exchange chromatography is one such method. Cation-exchange chromatography of lithium was carried out to investigate the lithium isotope effect in aqueous ion-exchange systems. The heavier isotope. 7 Li, was preferentially fractionated into the resin phase in every experiment conducted, and this result is consistent with the results of previous work. The value of the separation factor was 1.00089-1.00171 at 25C. A comparison of lithium isotope effect with those of potassium and rubidium indicated that the isotope effect originating from hydration is larger than the effect due to phase change for lithium, while the opposite is the case with potassium and rubidium

Development and application of liquid chromatography coupled to isotope ratio mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Zhang, Lijun

2014-02-19

Stable isotope analysis has found widespread applications in various disciplines such as archaeology, geochemistry, biology, food authenticity, and forensic science. Coupling chromatography to isotope ratio mass spectrometry for compound-specific isotope analysis (CSIA) is a trend, as it provides several advantages over bulk isotope analysis, e.g., relatively simple sample preparation, the ability to measure individual compounds in a complex mixture in one run, and the reduced sample size required for precise isotope analysis. Gas chromatography coupled to isotope ratio mass spectrometry (GC/IRMS) has been well-established for compound-specific isotope analysis of volatile organic compounds within the last two decades. However, an interface combining liquid chromatography with isotope ratio mass spectrometry (LC/IRMS) was not commercially available until 2004. The current design of the interface requires using a carbon-free eluent in chromatographic separation. This requirement limits the application of the most frequently used reversed-phase liquid chromatography in CSIA, because the elution strength of water at room temperature is too low to serve as mobile phase in reversed-phase separations. In order to increase the elution strength of water, we propose using high temperature water for chromatographic elution. The polarity of water decreases with an increase of temperature, yielding increased elution strength in reversed-phase columns. Therefore, high temperature water can be used as eluent instead of organic solvent for combining reversed-phase liquid chromatography with isotope ratio mass spectrometry (RPLC/IRMS). Additionally, temperature gradients can replace organic solvent gradients to increase chromatographic resolution. This is very important for LC/IRMS analysis, as precise isotope analysis requires baseline separation of analytes. In this thesis, high-temperature reversed-phase liquid chromatography was coupled to, and for the first time carefully

Development and application of liquid chromatography coupled to isotope ratio mass spectrometry

International Nuclear Information System (INIS)

Zhang, Lijun

2014-01-01

Stable isotope analysis has found widespread applications in various disciplines such as archaeology, geochemistry, biology, food authenticity, and forensic science. Coupling chromatography to isotope ratio mass spectrometry for compound-specific isotope analysis (CSIA) is a trend, as it provides several advantages over bulk isotope analysis, e.g., relatively simple sample preparation, the ability to measure individual compounds in a complex mixture in one run, and the reduced sample size required for precise isotope analysis. Gas chromatography coupled to isotope ratio mass spectrometry (GC/IRMS) has been well-established for compound-specific isotope analysis of volatile organic compounds within the last two decades. However, an interface combining liquid chromatography with isotope ratio mass spectrometry (LC/IRMS) was not commercially available until 2004. The current design of the interface requires using a carbon-free eluent in chromatographic separation. This requirement limits the application of the most frequently used reversed-phase liquid chromatography in CSIA, because the elution strength of water at room temperature is too low to serve as mobile phase in reversed-phase separations. In order to increase the elution strength of water, we propose using high temperature water for chromatographic elution. The polarity of water decreases with an increase of temperature, yielding increased elution strength in reversed-phase columns. Therefore, high temperature water can be used as eluent instead of organic solvent for combining reversed-phase liquid chromatography with isotope ratio mass spectrometry (RPLC/IRMS). Additionally, temperature gradients can replace organic solvent gradients to increase chromatographic resolution. This is very important for LC/IRMS analysis, as precise isotope analysis requires baseline separation of analytes. In this thesis, high-temperature reversed-phase liquid chromatography was coupled to, and for the first time carefully

Gas chromatography and isotope ratio mass spectrometry of Pinot Noir wine volatile compounds (δ13C) and solid residues (δ13C, δ15N) for the reassessment of vineyard water-status.

Science.gov (United States)

Spangenberg, Jorge E; Vogiatzaki, Maria; Zufferey, Vivian

2017-09-29

This paper describes a novel approach to reassess the water status in vineyards based on compound-specific isotope analysis (CSIA) of wine volatile organic compounds (δ 13 C VOC/VPDB ) and bulk carbon and nitrogen isotopes, and the C/N molar ratios of the wine solid residues (δ 13 C SR/VPDB , δ 15 N SR/Air-N2 ). These analyses link gas chromatography/combustion and elemental analysis to isotope ratio mass spectrometry (GC/C/IRMS, EA/IRMS). Field-grown cultivars of Pinot Noir grapevines were exposed during six growing seasons (2009-2014) to controlled soil water availability, while maintaining identical the other environmental variables and agricultural techniques. Wines were produced from the grapes by the same oenological protocol. This permitted for the assessment of the effects in the biochemistry of wines solely induced by the changes in the plant-soil water status. This mimicked the more recurrent and prolonged periods of soil water deficiency due to climate changes. Water stress in grapevine was assessed by the measurement of the predawn leaf water potential (Ψ pd ) and the stable carbon isotope composition of the berry sugars during harvest (must sugars). For quantitation purposes and the normalization of the measured stable carbon isotope ratios of the VOCs, the wine samples were spiked with three standard compounds with known concentration and δ 13 C VPDB values. VOCs were extracted by liquid-liquid extraction and analyzed by gas chromatography/flame ionization detection (GC/FID), gas chromatography/mass spectrometry (GC/MS), and GC/C/IRMS. δ 13 C values were obtained for eighteen VOCs. The solid residues were obtained by freeze-drying wine aliquots and were analyzed for their C and N content and isotope composition by EA/IRMS. All the isotopic ratios (δ 13 C SR , δ 15 N SR , δ 13 C VOC ) are highly correlated with the Ψ pd values, indicating that the proposed gas chromatography and isotope ratio mass spectrometry approach is a useful tool to

The isotope separation by ion exchange chromatography. Application to the lithium isotopes separation; La separation isotopique par chromatographie ionique

Energy Technology Data Exchange (ETDEWEB)

Albert, M G; Barre, Y; Neige, R

1994-12-31

In this work is described the used study step to demonstrate the industrial feasibility of a lithium isotopes separation process by ion exchange chromatography. After having recalled how is carried out the exchange reaction between the lithium isotopes bound on the cations exchanger resin and those which are in solution and gave the ion exchange chromatography principle, the authors establish a model which takes into account the cascade theory already used for enriched uranium production. The size parameters of this model are: the isotopic separation factor (which depends for lithium of the ligands nature and of the coordination factor), the isotopic exchange kinetics and the mass flow (which depends of the temperature, the lithium concentration, the resins diameter and the front advance). The way they have to be optimized and the implementation of the industrial process are given. (O.M.). 5 refs.

Boron isotopic enrichment by displacement chromatography

International Nuclear Information System (INIS)

Mohapatra, K.K.; Bose, Arun

2014-01-01

10 B enriched boron is used in applications requiring high volumetric neutron absorption (absorption cross section- 3837 barn for thermal and 1 barn for 1 MeV fast neutron). It is used in fast breeder reactor (as control rod material), in neutron counter, in Boron Neutron Capture Therapy etc. Owing to very small separation factor, boron isotopic enrichment is a complex process requiring large number of separation stages. Heavy Water Board has ventured in industrial scale production of 10 B enriched boron using Exchange Distillation Process as well as Ion Displacement Chromatography Process. Ion Displacement Chromatography process is used in Boron Enrichment Plant at HWP, Manuguru. It is based on isotopic exchange between borate ions (B(OH) 4 - ) on anion exchange resin and boric acid passing through resin. The isotopic exchange takes place due to difference in zero point energy of 10 B and 11 B

Measurement of Muscle Protein Fractional Synthetic Rate by Capillary Gas Chromatography/Combustion Isotope Ratio Mass Spectrometry

Science.gov (United States)

Yarasheski, Kevin E.; Smith, Kenneth; Rennie, Michael J.; Bier, Dennis M.

2014-01-01

The measurement of skeletal muscle protein fractional synthetic rate using an infusion of (1-13C)leucine and measuring the isotopic abundance of the tracer in skeletal muscle protein by preparative gas chromatography (GC)/ninhydrin isotope ratio mass spectrometry (IRMS) is laborious and subject to errors owing to contamination by 12C. The purpose of this study was to compare muscle (13C)leucine enrichment measured with the conventional preparative GC/ninhydrin IRMS approach to a new, continuous-flow technique using capillary GC/combustion IRMS. Quadriceps muscles were removed from four Sprague–Dawley rats after each was infused at a different rate with (1-13C)leucine for 6–8 h. Muscle leucine enrichment (at.% excess) measured by both methods differed by less than 4%, except at low (13C)leucine enrichments (IRMS was used to assess muscle (13C)leucine enrichment and fractional muscle protein synthesis rate in ten normal young men and women infused with (1,2-13C2)leucine for 12–14 h. This approach reduced the variability of the isotope abundance measure and gave estimates of muscle protein synthesis rate (0.050 ± 0.011% h−1 (mean ± SEM); range = 0.023–0.147% h−1) that agree with published values determined using the standard analytical approach. The measurement of (13C)leucine enrichment from skeletal muscle protein by capillary GC/combustion IRMS provides a simple, acceptable and practical alternative to preparative GC/ninhydrin IRMS. PMID:1420371

HDT mixtures treatment strategies by gas chromatography

Energy Technology Data Exchange (ETDEWEB)

Laquerbe, C.; Contreras, S.; Demoment, J. [Commissariat a l' Energie Atomique - CEA/Valduc, F-21121 Is sur Tille (France)

2008-07-15

Gas phase chromatographic processes are of interest for the separation of hydrogen isotopes from an HDT mixture. For a certain quantity, they are very competitive and present several benefits. Nevertheless no active packing material allows to have simultaneously good enrichment performances for tritium production and high decontamination capabilities for HD gases. The influence of the packing material is first described in this article. Then two specific processes (TCAP and Reverse Chromatography), each well adapted to perform one target, are presented. Finally, the problematic to propose an optimized treatment scheme associating these two processes is formulated. (authors)

HDT mixtures treatment strategies by gas chromatography

International Nuclear Information System (INIS)

Laquerbe, C.; Contreras, S.; Demoment, J.

2008-01-01

Gas phase chromatographic processes are of interest for the separation of hydrogen isotopes from an HDT mixture. For a certain quantity, they are very competitive and present several benefits. Nevertheless no active packing material allows to have simultaneously good enrichment performances for tritium production and high decontamination capabilities for HD gases. The influence of the packing material is first described in this article. Then two specific processes (TCAP and Reverse Chromatography), each well adapted to perform one target, are presented. Finally, the problematic to propose an optimized treatment scheme associating these two processes is formulated. (authors)

The isotope separation by ion exchange chromatography. Application to the lithium isotopes separation

International Nuclear Information System (INIS)

Albert, M.G.; Barre, Y.; Neige, R.

1993-01-01

In this work is described the used study step to demonstrate the industrial feasibility of a lithium isotopes separation process by ion exchange chromatography. After having recalled how is carried out the exchange reaction between the lithium isotopes bound on the cations exchanger resin and those which are in solution and gave the ion exchange chromatography principle, the authors establish a model which takes into account the cascade theory already used for enriched uranium production. The size parameters of this model are: the isotopic separation factor (which depends for lithium of the ligands nature and of the coordination factor), the isotopic exchange kinetics and the mass flow (which depends of the temperature, the lithium concentration, the resins diameter and the front advance). The way they have to be optimized and the implementation of the industrial process are given. (O.M.)

Quantification of Stable Isotope Traces Close to Natural Enrichment in Human Plasma Metabolites Using Gas Chromatography-Mass Spectrometry.

Science.gov (United States)

Krämer, Lisa; Jäger, Christian; Trezzi, Jean-Pierre; Jacobs, Doris M; Hiller, Karsten

2018-02-14

Currently, changes in metabolic fluxes following consumption of stable isotope-enriched foods are usually limited to the analysis of postprandial kinetics of glucose. Kinetic information on a larger diversity of metabolites is often lacking, mainly due to the marginal percentage of fully isotopically enriched plant material in the administered food product, and hence, an even weaker 13 C enrichment in downstream plasma metabolites. Therefore, we developed an analytical workflow to determine weak 13 C enrichments of diverse plasma metabolites with conventional gas chromatography-mass spectrometry (GC-MS). The limit of quantification was increased by optimizing (1) the metabolite extraction from plasma, (2) the GC-MS measurement, and (3) most importantly, the computational data processing. We applied our workflow to study the catabolic dynamics of 13 C-enriched wheat bread in three human subjects. For that purpose, we collected time-resolved human plasma samples at 16 timepoints after the consumption of 13 C-labeled bread and quantified 13 C enrichment of 12 metabolites (glucose, lactate, alanine, glycine, serine, citrate, glutamate, glutamine, valine, isoleucine, tyrosine, and threonine). Based on isotopomer specific analysis, we were able to distinguish catabolic profiles of starch and protein hydrolysis. More generally, our study highlights that conventional GC-MS equipment is sufficient to detect isotope traces below 1% if an appropriate data processing is integrated.

Quantification of Stable Isotope Traces Close to Natural Enrichment in Human Plasma Metabolites Using Gas Chromatography-Mass Spectrometry

Science.gov (United States)

Krämer, Lisa; Jäger, Christian; Jacobs, Doris M.; Hiller, Karsten

2018-01-01

Currently, changes in metabolic fluxes following consumption of stable isotope-enriched foods are usually limited to the analysis of postprandial kinetics of glucose. Kinetic information on a larger diversity of metabolites is often lacking, mainly due to the marginal percentage of fully isotopically enriched plant material in the administered food product, and hence, an even weaker 13C enrichment in downstream plasma metabolites. Therefore, we developed an analytical workflow to determine weak 13C enrichments of diverse plasma metabolites with conventional gas chromatography-mass spectrometry (GC-MS). The limit of quantification was increased by optimizing (1) the metabolite extraction from plasma, (2) the GC-MS measurement, and (3) most importantly, the computational data processing. We applied our workflow to study the catabolic dynamics of 13C-enriched wheat bread in three human subjects. For that purpose, we collected time-resolved human plasma samples at 16 timepoints after the consumption of 13C-labeled bread and quantified 13C enrichment of 12 metabolites (glucose, lactate, alanine, glycine, serine, citrate, glutamate, glutamine, valine, isoleucine, tyrosine, and threonine). Based on isotopomer specific analysis, we were able to distinguish catabolic profiles of starch and protein hydrolysis. More generally, our study highlights that conventional GC-MS equipment is sufficient to detect isotope traces below 1% if an appropriate data processing is integrated. PMID:29443915

Quantification of Stable Isotope Traces Close to Natural Enrichment in Human Plasma Metabolites Using Gas Chromatography-Mass Spectrometry

Directory of Open Access Journals (Sweden)

Lisa Krämer

2018-02-01

Full Text Available Currently, changes in metabolic fluxes following consumption of stable isotope-enriched foods are usually limited to the analysis of postprandial kinetics of glucose. Kinetic information on a larger diversity of metabolites is often lacking, mainly due to the marginal percentage of fully isotopically enriched plant material in the administered food product, and hence, an even weaker 13C enrichment in downstream plasma metabolites. Therefore, we developed an analytical workflow to determine weak 13C enrichments of diverse plasma metabolites with conventional gas chromatography-mass spectrometry (GC-MS. The limit of quantification was increased by optimizing (1 the metabolite extraction from plasma, (2 the GC-MS measurement, and (3 most importantly, the computational data processing. We applied our workflow to study the catabolic dynamics of 13C-enriched wheat bread in three human subjects. For that purpose, we collected time-resolved human plasma samples at 16 timepoints after the consumption of 13C-labeled bread and quantified 13C enrichment of 12 metabolites (glucose, lactate, alanine, glycine, serine, citrate, glutamate, glutamine, valine, isoleucine, tyrosine, and threonine. Based on isotopomer specific analysis, we were able to distinguish catabolic profiles of starch and protein hydrolysis. More generally, our study highlights that conventional GC-MS equipment is sufficient to detect isotope traces below 1% if an appropriate data processing is integrated.

Stable carbon isotope analyses of nanogram quantities of particulate organic carbon (pollen) with laser ablation nano combustion gas chromatography/isotope ratio mass spectrometry

Science.gov (United States)

Sluijs, Appy; Laks, Jelmer J.; Reichart, Gert‐Jan

2016-01-01

Rationale Analyses of stable carbon isotope ratios (δ 13C values) of organic and inorganic matter remains have been instrumental for much of our understanding of present and past environmental and biological processes. Until recently, the analytical window of such analyses has been limited to samples containing at least several μg of carbon. Methods Here we present a setup combining laser ablation, nano combustion gas chromatography and isotope ratio mass spectrometry (LA/nC/GC/IRMS). A deep UV (193 nm) laser is used for optimal fragmentation of organic matter with minimum fractionation effects and an exceptionally small ablation chamber and combustion oven are used to reduce the minimum sample mass requirement compared with previous studies. Results Analyses of the international IAEA CH‐7 polyethylene standard show optimal accuracy, and precision better than 0.5‰, when measuring at least 42 ng C. Application to untreated modern Eucalyptus globulus (C3 plant) and Zea mays (C4 plant) pollen grains shows a ~ 16‰ offset between these species. Within each single Z. mays pollen grain, replicate analyses show almost identical δ 13C values. Conclusions Isotopic offsets between individual pollen grains exceed analytical uncertainties, therefore probably reflecting interspecimen variability of ~0.5–0.9‰. These promising results set the stage for investigating both δ 13C values and natural carbon isotopic variability between single specimens of a single population of all kinds of organic particles yielding tens of nanograms of carbon. © 2016 The Authors. Rapid Communications in Mass Spectrometry Published by John Wiley & Sons Ltd. PMID:27766694

Study on atmospheric hydrogen enrichment by cryopump method and isotope separation by gas chromatography

International Nuclear Information System (INIS)

Taniyama, Yuki; Momoshima, Noriyuki

2001-01-01

To obtain the information of source of atmospheric hydrogen tritium an analysis of tritium isotopes is thought to be effective. So an atmospheric hydrogen enrichment apparatus and a cryogenic gas chromatographic column were made. Experiments were carried out to study the performance of cryopump to enrich atmospheric hydrogen and the column to separate hydrogen isotopes that obtained by cryopump method. The cryopump was able to process about 1000 1 atmosphere and the column was able to separate hydrogen isotopes with good resolution. (author)

Identification of fentanyl metabolites in rat urine by gas chromatography-mass spectrometry with stable-isotope tracers

Energy Technology Data Exchange (ETDEWEB)

Goromaru, T.; Matsuura, H.; Furuta, T.; Baba, S.; Yoshimura, N.; Miyawaki, T.; Sameshima, T.

The metabolites of fentanyl (l), which has been widely used as a neuroleptic analgesic agent, were identified in urine of rats by gas chromatography-mass spectrometry combined with a stable-isotope tracer technique. After the oral administration of an equimolar mixture of l and deuterium-labeled l (l/l-d5), the urinary metabolites were extracted with chloroform at pH 9.0. Extracts were derivatized and analyzed by GC/MS. Metabolites were identified by the presence of doublet ion peaks separated by 5 amu, and chemical structures were established from analyses of fragmentation pathways. The metabolites were identified as 4-N-(N-propionylanilino)-piperidine, 4-N-(N-hydroxypropionylanilino)piperidine, 4-N-(N-propionylanilino) hydroxypiperidine, 1-(2-phenethyl)-4-N-(N-hydroxypropionylanilino)piperidine and 1-(2-phenethyl)-4-N-(N-propionylanilino)hydroxypiperidine. These metabolites, together with unchanged l, were also detected in urine of rats receiving l/l-d5 intravenously, by selected-ion monitoring of the specific cluster ions.

Determination of the alkylpyrazine composition of coffee using stable isotope dilution-gas chromatography-mass spectrometry (SIDA-GC-MS).

Science.gov (United States)

Pickard, Stephanie; Becker, Irina; Merz, Karl-Heinz; Richling, Elke

2013-07-03

A stable isotope dilution analysis based on gas chromatography-mass spectrometry analysis (SIDA-GC-MS) was developed for the quantitative analysis of 12 alkylpyrazines found in commercially available coffee samples. These compounds contribute to coffee flavor. The accuracy of this method was tested by analyzing model mixtures of alkylpyrazines. Comparisons of alkylpyrazine-concentrations suggested that water as extraction solvent was superior to dichloromethane. The distribution patterns of alkylpyrazines in different roasted coffees were quite similar. The most abundant alkylpyrazine in each coffee sample was 2-methylpyrazine, followed by 2,6-dimethylpyrazine, 2,5-dimethylpyrazine, 2-ethylpyrazine, 2-ethyl-6-methylpyrazine, 2-ethyl-5-methylpyrazine, and 2,3,5-trimethylpyrazine, respectively. Among the alkylpyrazines tested, 2,3-dimethylpyrazine, 2-ethyl-3-methylpyrazine, 2-ethyl-3,6-dimethylpyrazine, and 2-ethyl-3,5-dimethylpyrazine revealed the lowest concentrations in roasted coffee. By the use of isotope dilution analysis, the total concentrations of alkylpyrazines in commercially available ground coffee ranged between 82.1 and 211.6 mg/kg, respectively. Decaffeinated coffee samples were found to contain lower amounts of alkylpyrazines than regular coffee samples by a factor of 0.3-0.7, which might be a result of the decaffeination procedure.

Possibilities of gas-phase radio-chromatography application to permanent-gas analysis

International Nuclear Information System (INIS)

Dupuis, M.C.; Charrier, G.; Alba, C.; Massimino, D.

1970-01-01

The gas-phase radio-chromatography technique has been applied to the rapid analysis of permanent gases (H 2 , O 2 , N 2 , A, Kr, Xe, CO, CH 4 ) labelled with radioactive indicators ( 3 H, 37 A, 85 Kr, 133 Xe). After calibration, the components of such a mixture can be identified and their concentrations measured in less than two hours, using a sample volume of from 0.1 to 10 cm 3 . The minimum detectable activity is of the order of 10 -4 μC for each radioactive isotope. The measurements are reproducible to about 2 to 3 per cent. This work has been mainly concerned with the influence of parameters affecting the response of the radioactivity detector (ionization chamber or gas flow proportional counter). The method has very numerous applications both theoretically, for the study of chromatographic phenomena under ideal conditions (infinitesimal concentrations made possible by the use of radioactive tracers), and practically, for rapid and accurate radiochemical analysis of radioactive gas mixtures. (authors) [fr

Simultaneous analysis of (13)C-glutathione as its dimeric form GSSG and its precursor [1-(13)C]glycine using liquid chromatography/isotope ratio mass spectrometry

NARCIS (Netherlands)

Schierbeek, Henk; Rook, Denise; te Braake, Frans W. J.; Dorst, Kristien Y.; Voortman, Gardi; Godin, Jean-Philippe; Fay, Laurent-Bernard; van Goudoever, Johannes B.

2009-01-01

Determination of glutathione kinetics using stable isotopes requires accurate measurement of the tracers and tracees. Previously, the precursor and synthesized product were measured with two separate techniques, liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) and gas

Studies on the separation of hydrogen isotopes and spin isomers by gas chromatography

International Nuclear Information System (INIS)

Pushpa, K.K.; Annaji Rao, K.

2000-08-01

Separation and analysis of mixture of hydrogen isotopes has gained considerable importance because of various applications needing different isotopes in lasers, nuclear reactions and tracer or labelled compounds. In the literature gas chromatographic methods are reported using columns packed with partly dehydrated or thoroughly dehydrated alumina/molecular sieve stationary phase at 77 deg K with helium, neon and even hydrogen or deuterium as carrier gas. In the present study an attempt is made to compare the chromatographic behaviour of these two stationary phases using virgin and Fe doped form in partly dehydrated and thoroughly dehydrated state, using helium, neon, hydrogen and deuterium as carrier gas. The results of this study show that helium or neon carrier gas behave similarly broad peaks with some tailing. Sharp symmetric peaks are obtained with hydrogen or deuterium carrier gas. This is attributed to large hold up capacity for H 2 or D 2 at 77 deg K in these materials as compared to helium or neon. Spin isomers of H 2 or D 2 are separated on Fe free stationary phases, though ortho H 2 and HD are not resolved. Using a combination of Fe doped short column and plain alumina column, both maintained in dehydrated form, the effect of Fe doping on thermal equilibrium of ortho/para forms at 77 deg K is clearly demonstrated. (author)

Magnesium isotope fractionation in cation-exchange chromatography

International Nuclear Information System (INIS)

Oi, T.; Yanase, S.; Kakihana, H.

1987-01-01

Band displacement chromatography of magnesium has been carried out successfully for the purpose of magnesium isotope separation by using a strongly acidic cation-exchange resin and the strontium ion as the replacement ion. A small but definite accumulation of the heavier isotopes ( 25 Mg, 26 Mg) has been observed at the front parts of the magnesium chromatograms. The heavier isotopes have been fractionated preferentially into the solution phase. The single-stage separation factors have been calculated for the 25 Mg/ 24 Mg and 26 Mg/ 24 isotopic pairs at 25 0 C. The reduced partition function ratios of magnesium species involved in the present study have been estimated

Determination of radiochemical purity using gas chromatography

International Nuclear Information System (INIS)

1975-01-01

The concepts of chromatography, gas chromatography, activity, radiochemical impurity are defined; the procedure of the application of gas chromatography for detecting radiochemical purity of substances is standardized. (E.F.)

Single-step transesterification with simultaneous concentration and stable isotope analysis of fatty acid methyl esters by gas chromatography-combustion-isotope ratio mass spectrometry.

Science.gov (United States)

Panetta, Robert J; Jahren, A Hope

2011-05-30

Gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) is increasingly applied to food and metabolic studies for stable isotope analysis (δ(13) C), with the quantification of analyte concentration often obtained via a second alternative method. We describe a rapid direct transesterification of triacylglycerides (TAGs) for fatty acid methyl ester (FAME) analysis by GC-C-IRMS demonstrating robust simultaneous quantification of amount of analyte (mean r(2) =0.99, accuracy ±2% for 37 FAMEs) and δ(13) C (±0.13‰) in a single analytical run. The maximum FAME yield and optimal δ(13) C values are obtained by derivatizing with 10% (v/v) acetyl chloride in methanol for 1 h, while lower levels of acetyl chloride and shorter reaction times skewed the δ(13) C values by as much as 0.80‰. A Bland-Altman evaluation of the GC-C-IRMS measurements resulted in excellent agreement for pure oils (±0.08‰) and oils extracted from French fries (±0.49‰), demonstrating reliable simultaneous quantification of FAME concentration and δ(13) C values. Thus, we conclude that for studies requiring both the quantification of analyte and δ(13) C data, such as authentication or metabolic flux studies, GC-C-IRMS can be used as the sole analytical method. Copyright © 2011 John Wiley & Sons, Ltd.

Gas chromatography in space

Science.gov (United States)

Akapo, S. O.; Dimandja, J. M.; Kojiro, D. R.; Valentin, J. R.; Carle, G. C.

1999-01-01

Gas chromatography has proven to be a very useful analytical technique for in situ analysis of extraterrestrial environments as demonstrated by its successful operation on spacecraft missions to Mars and Venus. The technique is also one of the six scientific instruments aboard the Huygens probe to explore Titan's atmosphere and surface. A review of gas chromatography in previous space missions and some recent developments in the current environment of fiscal constraints and payload size limitations are presented.

LabData database sub-systems for post-processing and quality control of stable isotope and gas chromatography measurements

Science.gov (United States)

Suckow, A. O.

2013-12-01

Measurements need post-processing to obtain results that are comparable between laboratories. Raw data may need to be corrected for blank, memory, drift (change of reference values with time), linearity (dependence of reference on signal height) and normalized to international reference materials. Post-processing parameters need to be stored for traceability of results. State of the art stable isotope correction schemes are available based on MS Excel (Geldern and Barth, 2012; Gröning, 2011) or MS Access (Coplen, 1998). These are specialized to stable isotope measurements only, often only to the post-processing of a special run. Embedding of algorithms into a multipurpose database system was missing. This is necessary to combine results of different tracers (3H, 3He, 2H, 18O, CFCs, SF6...) or geochronological tools (Sediment dating e.g. with 210Pb, 137Cs), to relate to attribute data (submitter, batch, project, geographical origin, depth in core, well information etc.) and for further interpretation tools (e.g. lumped parameter modelling). Database sub-systems to the LabData laboratory management system (Suckow and Dumke, 2001) are presented for stable isotopes and for gas chromatographic CFC and SF6 measurements. The sub-system for stable isotopes allows the following post-processing: 1. automated import from measurement software (Isodat, Picarro, LGR), 2. correction for sample-to sample memory, linearity, drift, and renormalization of the raw data. The sub-system for gas chromatography covers: 1. storage of all raw data 2. storage of peak integration parameters 3. correction for blank, efficiency and linearity The user interface allows interactive and graphical control of the post-processing and all corrections by export to and plot in MS Excel and is a valuable tool for quality control. The sub-databases are integrated into LabData, a multi-user client server architecture using MS SQL server as back-end and an MS Access front-end and installed in four

Calcium isotope fractionation in ion-exchange chromatography

International Nuclear Information System (INIS)

Russell, W.A.; Papanastassiou, D.A.

1978-01-01

Significant fractionation of the isotopes of calcium has been observed during elution through short ion-exchange columns packed with Dowex 50W-X8 resin. A double isotopic tracer was used to provide correction for instrumental fractionation effects. The absolute 40 Ca/ 44 Ca ratio is determined by this method to 0.05% and provides a measure of the fractionation of all Ca isotopes. It is found that the lighter isotopes are preferentially retained by the resin, with variations in 40 Ca/ 44 Ca between the first and last fractions of up to 1.1%. An estimate of the separation factor between batch solute and resin gives epsilon = 2.1 x 10 -4 . Details of the chemical or physical mechanisms causing isotope fractionation of Li, Na, Ca, and other elements during ion-exchange chromatography are not yet clear

Boron isotope fractionation in column chromatography with glucamine type fibers

International Nuclear Information System (INIS)

Sonoda, Akinari; Makita, Yoji; Hirotsu, Takahiro

2008-01-01

Glucamine type polymers have specific affinity toward boric acid and borate ion. Among them, Chelest Fiber GRY-L showed larger fractionation for boron isotopes than other polymers in our previous study. For this study, we used Chelest Fibers with different fiber lengths (1.0 mm, 0.5 mm, and 0.3 mm) as column packing materials to perform chromatographic separation of boron isotopes. The shorter fiber has larger packing density when packed into the column using a dry method. The 0.3-mm-long fiber has a larger backpressure than fibers of other lengths. Boron adsorption capacities were measured using the breakthrough operation. At this time, the 0.5-mm-long fiber showed the highest capacity. When we measured the isotope ratio profile for fibers of different length using column chromatography, 0.5-mm-long fibers displayed the highest boron isotope fractionation. The 0.5-mm-long fiber is promising as a packing material of column chromatography for boron isotope separation. We also changed operation methods. The lower eluent concentration and the slower flow rate are suitable for boron isotope separation. (author)

Novel Apparatus for the Real-Time Quantification of Dissolved Gas Concentrations and Isotope Ratios

Science.gov (United States)

Gupta, M.; Leen, J.; Baer, D. S.; Owano, T. G.; Liem, J.

2013-12-01

Measurements of dissolved gases and their isotopic composition are critical in studying a variety of phenomena, including underwater greenhouse gas generation, air-surface exchange, and pollution migration. These studies typically involve obtaining water samples from streams, lakes, or ocean water and transporting them to a laboratory, where they are degased. The gases obtained are then generally measured using gas chromatography and isotope ratio mass spectrometry for concentrations and isotope ratios, respectively. This conventional, off-line methodology is time consuming, significantly limits the number of the samples that can be measured and thus severely inhibits detailed spatial and temporal mapping of gas concentrations and isotope ratios. In this work, we describe the development of a new membrane-based degassing device that interfaces directly to Los Gatos Research (cavity enhanced laser absorption or Off-Axis ICOS) gas analyzers (cavity enhanced laser absorption or Off-Axis ICOS analyzers) to create an autonomous system that can continuously and quickly measure concentrations and isotope ratios of dissolved gases in real time in the field. By accurately controlling the water flow rate through the membrane degasser, gas pressure on the outside of the membrane, and water pressure on the inside of the membrane, the system is able to generate precise and highly reproducible results. Moreover, by accurately measuring the gas flow rates in and out of the degasser, the gas-phase concentrations (ppm) could be converted into dissolved gas concentrations (nM). We will present detailed laboratory test data that quantifies the linearity, precision, and dynamic range of the system for the concentrations and isotope ratios of dissolved methane, carbon dioxide, and nitrous oxide. By interfacing the degassing device to a novel cavity-enhanced spectrometer (developed by LGR), preliminary data will also be presented for dissolved volatile organics (VOC) and other

Development of a new method for hydrogen isotope analysis of trace hydrocarbons in natural gas samples

Directory of Open Access Journals (Sweden)

Xibin Wang

2016-12-01

Full Text Available A new method had been developed for the analysis of hydrogen isotopic composition of trace hydrocarbons in natural gas samples by using solid phase microextraction (SPME combined with gas chromatography-isotope ratio mass spectrometry (GC/IRMS. In this study, the SPME technique had been initially introduced to achieve the enrichment of trace content of hydrocarbons with low abundance and coupled to GC/IRMS for hydrogen isotopic analysis. The main parameters, including the equilibration time, extraction temperature, and the fiber type, were systematically optimized. The results not only demonstrated that high extraction yield was true but also shows that the hydrogen isotopic fractionation was not observed during the extraction process, when the SPME device fitted with polydimethylsiloxane/divinylbenzene/carbon molecular sieve (PDMS/DVB/CAR fiber. The applications of SPME-GC/IRMS method were evaluated by using natural gas samples collected from different sedimentary basins; the standard deviation (SD was better than 4‰ for reproducible measurements; and also, the hydrogen isotope values from C1 to C9 can be obtained with satisfying repeatability. The SPME-GC/IRMS method fitted with PDMS/DVB/CAR fiber is well suited for the preconcentration of trace hydrocarbons, and provides a reliable hydrogen isotopic analysis for trace hydrocarbons in natural gas samples.

Trends in the analysis of natural gas by capillary gas chromatography

NARCIS (Netherlands)

Cramers, C.A.M.G.; Rossum, van G.J.

1986-01-01

The importance of correct determination of physical and chemical properties of natural gas is evident. The calculation of calorific value or hydrocarbon dew point requires detailed analysis as can be provided by gas chromatography. Analysis by gas chromatography is a necessary complement to direct

Gas chromatography at the Tritium Laboratory Karlsruhe

International Nuclear Information System (INIS)

Laesser, R.; Gruenhagen, S.

2003-08-01

Among the analytical techniques (mass spectrometry, laser Raman spectroscopy, gas chromatography, use of ionisation chambers) employed at the Tritium Laboratory Karlsruhe (TLK), gas chromatography plays a prominent role. The main reasons for that are the simplicity of the gas chromatographic separation process, the small space required for the equipment, the low investment costs in comparison to other methods, the robustness of the equipment, the simple and straightforward analysis and the fact that all gas species of interest (with the exception of water) can easily be detected by gas chromatographic means. The conventional gas chromatographs GC1 and GC2 used in the Tritium Measurement Techniques (TMT) System of the TLK and the gas chromatograph GC3 of the experiment CAPER are presented in detail, by discussing their flow diagrams, their major components, the chromatograms measured by means of various detectors, shortcomings and possible improvements. One of the main disadvantages of the conventional gas chromatography is the long retention times required for the analysis of hydrogen gas mixtures. To overcome this disadvantage, micro gas chromatography for hydrogen analysis was developed. Reduction of the retention times by one order of magnitude was achieved. (orig.)

Comparison of liquid chromatography-isotope ratio mass spectrometry (LC/IRMS) and gas chromatography-combustion-isotope ratio mass spectrometry (GC/C/IRMS) for the determination of collagen amino acid δ13C values for palaeodietary and palaeoecological reconstruction.

Science.gov (United States)

Dunn, Philip J H; Honch, Noah V; Evershed, Richard P

2011-10-30

Results are presented of a comparison of the amino acid (AA) δ(13)C values obtained by gas chromatography-combustion-isotope ratio mass spectrometry (GC/C/IRMS) and liquid chromatography-isotope ratio mass spectrometry (LC/IRMS). Although the primary focus was the compound-specific stable carbon isotope analysis of bone collagen AAs, because of its growing application for palaeodietary and palaeoecological reconstruction, the results are relevant to any field where AA δ(13)C values are required. We compare LC/IRMS with the most up-to-date GC/C/IRMS method using N-acetyl methyl ester (NACME) AA derivatives. This comparison involves the analysis of standard AAs and hydrolysates of archaeological human bone collagen, which have been previously investigated as N-trifluoroacetyl isopropyl esters (TFA/IP). It was observed that, although GC/C/IRMS analyses required less sample, LC/IRMS permitted the analysis of a wider range of AAs, particularly those not amenable to GC analysis (e.g. arginine). Accordingly, reconstructed bulk δ(13)C values based on LC/IRMS-derived δ(13)C values were closer to the EA/IRMS-derived δ(13)C values than those based on GC/C/IRMS values. The analytical errors for LC/IRMS AA δ(13)C values were lower than GC/C/IRMS determinations. Inconsistencies in the δ(13)C values of the TFA/IP derivatives compared with the NACME- and LC/IRMS-derived δ(13)C values suggest inherent problems with the use of TFA/IP derivatives, resulting from: (i) inefficient sample combustion, and/or (ii) differences in the intra-molecular distribution of δ(13)C values between AAs, which are manifested by incomplete combustion. Close similarities between the NACME AA δ(13)C values and the LC/IRMS-derived δ(13)C values suggest that the TFA/IP derivatives should be abandoned for the natural abundance determinations of AA δ(13)C values. Copyright © 2011 John Wiley & Sons, Ltd.

Carbon isotopic analysis of atmospheric methane by isotope-ratio-monitoring gas chromatography-mass spectrometry

Science.gov (United States)

Merritt, Dawn A.; Hayes, J. M.; Des Marais, David J.

1995-01-01

Less than 15 min are required for the determination of delta C(sub PDB)-13 with a precision of 0.2 ppt(1 sigma, single measurement) in 5-mL samples of air containing CH4 at natural levels (1.7 ppm). An analytical system including a sample-introduction unit incorporating a preparative gas chromatograph (GC) column for separation of CH4 from N2, O2, and Ar is described. The 15-min procedure includes time for operation of that system, high-resolution chromatographic separation of the CH4, on-line combustion and purification of the products, and isotopic calibration. Analyses of standards demonstrate that systematic errors are absent and that there is no dependence of observed values of delta on sample size. For samples containing 100 ppm or more CH4, preconcentration is not required and the analysis time is less than 5 min. The system utilizes a commercially available, high-sensitivity isotope-ratio mass spectrometer. For optimal conditions of smaple handling and combustion, performance of the system is within a factor of 2 of the shot-noise limit. The potential exists therefore for analysis of samples as small as 15 pmol CH4 with a standard deviation of less than 1 ppt.

Analysis of pollutants in air and water using gas chromatography and headspace gas chromatography

Energy Technology Data Exchange (ETDEWEB)

Stenner, H.

1980-01-01

The combination 'personal sampling' with headspace gas chromatography to determine traces of formaldehyde, phenol and benzene in air is investigated in this work, with the aim of developing maximum workplace concentration values (MWL values). Further possible applications of gas chromatography in trace analysis in the environmentally protected area. The analysis of chromium in waste waters (Cr III as acetyl acetonate complex) is investigated as further possible application, whereby optimum conditions are obtained. A modified flame ionization detector was used to increase the detection sensitivity.

Gas chromatography/ion trap mass spectrometry applied for the analysis of triazine herbicides in environmental waters by an isotope dilution technique

International Nuclear Information System (INIS)

Cai Zongwei; Wang Dongli; Ma, W.T.

2004-01-01

A gas chromatography/ion trap mass spectrometry method was developed for the analysis of simazine, atrazine, cyanazine, as well as the degradation products of atrazine, such as deethylatrazine and deisopropylatrazine in environmental water samples. Isotope dilution technique was applied for the quantitative analysis of atrazine in water at low ng/l levels. One liter of water sample spiked with stable isotope internal standard atrazine-d 5 was extracted with a C 18 solid-phase extraction cartridge. The analysis was performed on an ion trap mass spectrometer operated in MS/MS method. The extraction recoveries were in the range of 83-94% for the triazine herbicides in water at the concentrations of 24, 200, and 1000 ng/l, while poor recoveries were obtained for the degradation products of atrazine. The relative standard deviation (R.S.D.) were within the range of 3.2-16.1%. The detection limits of the method were between 0.75 and 12 ng/l when 1 l of water was analyzed. The method was successfully applied to analyze environmental water samples collected from a reservoir and a river in Hong Kong for atrazine detected at concentrations between 3.4 and 26 ng/l

An improved reference measurement procedure for triglycerides and total glycerides in human serum by isotope dilution gas chromatography-mass spectrometry.

Science.gov (United States)

Chen, Yizhao; Liu, Qinde; Yong, Sharon; Teo, Hui Ling; Lee, Tong Kooi

2014-01-20

Triglycerides are widely tested in clinical laboratories using enzymatic methods for lipid profiling. As enzymatic methods can be affected by interferences from biological samples, this together with the non-specific nature of triglycerides measurement makes it necessary to verify the accuracy of the test results with a reference measurement procedure. Several such measurement procedures had been published. These procedures generally involved lengthy and laborious sample preparation steps. In this paper, an improved reference measurement procedure for triglycerides and total glycerides was reported which simplifies the sample preparation steps and greatly shortens the time taken. The procedure was based on isotope dilution gas chromatography-mass spectrometry (IDGC-MS)with tripalmitin as the calibration standard. Serum samples were first spiked with isotope-labeled tripalmitin. For the measurement of triglycerides, the serum samples were subjected to lipid extraction followed by separation of triglycerides from diglycerides and monoglycerides. Triglycerides were then hydrolyzed to glycerol, derivatized and injected into the GC–MS for quantification. For the measurement of total glycerides, the serum samples were hydrolyzed directly and derivatized before injection into the GC-MS for quantification. All measurement results showed good precision with CV triglycerides and total glycerides were well within the certified ranges of the CRM, with deviation triglycerides and total glycerides.

Comparative determination of phenytoin by spectrophotometry, gas chromatography, liquid chromatography, enzyme immunoassay, and radioimmunoassay

International Nuclear Information System (INIS)

Castro, A.; Ibanez, J.; DiCesare, J.L.; Adams, R.F.; Malkus, H.

1978-01-01

Sera from patients being treated with phenytoin were analyzed for the drug by spectrophotometry, gas chromatography, radioimmunoasay, enzyme immunoassay, and liquid chromatography. The assay values obtained were intercompared statistically. Enzyme immunoassay and liquid chromatography appear to be attractive alternatives to the more traditional methods of spectrophotometry and gas chromatography. Our radioimmunoassay data correlated poorly with results by the four other methods

Application of gas chromatography-mass spectrometry/combustion/isotope ratio mass spectrometry (GC-MS/C/IRMS) to detect the abuse of 17β-estradiol in cattle.

Science.gov (United States)

Janssens, Geert; Mangelinckx, Sven; Courtheyn, Dirk; Prévost, Stéphanie; De Poorter, Geert; De Kimpe, Norbert; Le Bizec, Bruno

2013-07-31

Although the ability to differentiate between endogenous steroids and synthetic homologues on the basis of their (13)C/(12)C isotopic ratio has been known for over a decade, this technique has been scarcely implemented for food safety purposes. In this study, a method was developed using gas chromatography-mass spectrometry/combustion/isotope ratio mass spectrometry (GC-MS/C/IRMS) to demonstrate the abuse of 17β-estradiol in cattle, by comparison of the (13)C/(12)C ratios of the main metabolite 17α-estradiol and an endogenous reference compound (ERC), 5-androstene-3β,17α-diol, in bovine urine. The intermediate precisions were determined as 0.46 and 0.26‰ for 5-androstene-3β,17α-diol and 17α-estradiol, respectively. This is, to the authors' knowledge, the first reported use of GC-MS/C/IRMS for the analysis of steroid compounds for food safety issues.

XII All-Russian conference on gas chromatography. Program. Summary of reports

International Nuclear Information System (INIS)

2002-01-01

Program and summary of reports of the XII All-Russian conference on gas chromatography are performed. The conference took place in Samara, 10-14 June, 2002. Reports on physicochemical regularities of gas chromatography, application of chromatographic methods in atomic energetics are included in the program of the conference. Part of the reports are deleted to the analytical application of the gas chromatography. Adsorbents for the gas chromatography, complex methods, mathematic methods in chromatography, ecological aspects of the gas chromatography [ru

Ionic liquid stationary phases for gas chromatography.

Science.gov (United States)

Poole, Colin F; Poole, Salwa K

2011-04-01

This article provides a summary of the development of ionic liquids as stationary phases for gas chromatography beginning with early work on packed columns that established details of the retention mechanism and established working methods to characterize selectivity differences compared with molecular stationary phases through the modern development of multi-centered cation and cross-linked ionic liquids for high-temperature applications in capillary gas chromatography. Since there are many reviews on ionic liquids dealing with all aspects of their chemical and physical properties, the emphasis in this article is placed on the role of gas chromatography played in the design of ionic liquids of low melting point, high thermal stability, high viscosity, and variable selectivity for separations. Ionic liquids provide unprecedented opportunities for extending the selectivity range and temperature-operating range of columns for gas chromatography, an area of separation science that has otherwise been almost stagnant for over a decade. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stable carbon and hydrogen isotope analysis of methyl tert-butyl ether and tert-amyl methyl ether by purge and trap-gas chromatography-isotope ratio mass spectrometry: method evaluation and application.

Science.gov (United States)

Kujawinski, Dorothea M; Stephan, Manuel; Jochmann, Maik A; Krajenke, Karen; Haas, Joe; Schmidt, Torsten C

2010-01-01

In order to monitor the behaviour of contaminants in the aqueous environment effective enrichment techniques often have to be employed due to their low concentrations. In this work a robust and sensitive purge and trap-gas chromatography-isotope ratio mass spectrometry method for carbon and hydrogen isotope analysis of fuel oxygenates in water is presented. The method evaluation included the determination of method detection limits, accuracy and reproducibility of deltaD and delta(13)C values. Lowest concentrations at which reliable delta(13)C values could be determined were 5 microg L(-1) and 28 microg L(-1) for TAME and MTBE, respectively. Stable deltaD values for MTBE and TAME could be achieved for concentrations as low as 25 and 50 microg L(-1). Good long-term reproducibility of delta(13)C and deltaD values was obtained for all target compounds. But deltaD values varying more than 5 per thousand were observed using different thermal conversion tubes. Thus, a correction of deltaD values in the analysis of groundwater samples was necessary to guarantee comparability of the results. The applicability of this method was shown by the analysis of groundwater samples from a gasoline contaminated site. By two dimensional isotope analysis two locations within this site were identified at which anaerobic and aerobic degradation of methyl tert-butyl ether occurred.

Performance and optimization of a combustion interface for isotope ratio monitoring gas chromatography/mass spectrometry

Science.gov (United States)

Merritt, D. A.; Freeman, K. H.; Ricci, M. P.; Studley, S. A.; Hayes, J. M.

1995-01-01

Conditions and systems for on-line combustion of effluents from capillary gas chromatographic columns and for removal of water vapor from product streams were tested. Organic carbon in gas chromatographic peaks 15 s wide and containing up to 30 nanomoles of carbon was quantitatively converted to CO2 by tubular combustion reactors, 200 x 0.5 mm, packed with CuO or NiO. No auxiliary source of O2 was required because oxygen was supplied by metal oxides. Spontaneous degradation of CuO limited the life of CuO reactors at T > 850 degrees C. Since NiO does not spontaneously degrade, its use might be favored, but Ni-bound carbon phases form and lead to inaccurate isotopic results at T Water must be removed from the gas stream transmitted to the mass spectrometer or else protonation of CO2 will lead to inaccuracy in isotopic analyses. Although thresholds for this effect vary between mass spectrometers, differential permeation of H2O through Nafion tubing was effective in both cases tested, but the required length of the Nafion membrane was 4 times greater for the more sensitive mass spectrometer.

The influence of different referencing methods on the accuracy of δ(13) C value measurement of ethanol fuel by gas chromatography/combustion/isotope ratio mass spectrometry.

Science.gov (United States)

Neves, Laura A; Rodrigues, Janaína M; Daroda, Romeu J; Silva, Paulo R M; Ferreira, Alexandre A; Aranda, Donato A G; Eberlin, Marcos N; Fasciotti, Maíra

2015-11-15

Brazil is the largest producer of sugar cane bioethanol in the world. Isotope ratio mass spectrometry (IRMS) is the technique of choice to certify the origin/raw materials for ethanol production, but the lack of certified reference materials (CRMs) for accurate measurements of δ(13) C values traceable to Vienna Pee Dee Belemnite (VPDB), the international zero point for (13) C/(12) C measurements, certified and compatible with gas chromatography (GC)/IRMS instruments may compromise the accuracy of δ(13) C determinations. We evaluated the influence of methods for the calibration and normalization of raw δ(13) C values of ethanol samples. Samples were analyzed by GC/C/IRMS using two different GC columns. Different substances were used as isotopic standards for the working gas calibration. The δ(13) C values obtained with the three methods of normalization were statistically compared with those obtained with elemental analyzer (EA)/IRMS, since the δ(13) C results obtained using EA are traceable to VPDB via the NBS 22 reference material. It was observed that both the isotopic reference material for CO2 calibration and the GC column have a major effect on the δ(13) C measurements, leading to a bias of almost 2-3 ‰ in the δ(13) C values. All three methods of normalization were equivalent in performance, enabling an improvement in the GC/C/IRMS accuracy, compared with the EA/IRMS reference values for the samples. All the methods of CO2 calibration, chromatography and normalization presented in this work demonstrated several sources of traceability and accuracy loss for the determination of δ(13) C values in ethanol fuel samples by GC/C/IRMS. This work has also shown the importance of using proper CRMs traceable to VPBD that should be compatible and certified using GC/C/IRMS, ideally in a wide range of δ(13) C values. This is important not only for bioethanol fuel samples, but also for many analytes commonly analyzed by IRMS. Copyright © 2015 John Wiley & Sons

Applications of the gas chromatography in the nuclear science and technology; Aplicaciones de la cromatografia de gases a la ciencia y tecnologia nuclear

Energy Technology Data Exchange (ETDEWEB)

Gasco Sanchez, L

1972-07-01

This paper is a review on the applications of the gas chromatography in the nuclear science and technology published up to December 1971. Its contents has been classified under the following heads; I) Radiogaschromatography, II) Isotope separation, III) Preparation of labelled molecules, IV) Nuclear fuel cycle, V) Nuclear reactor technology, VI) Irradiation chemistry, VIl) Separation of me tal compounds in gas phase, VIII) Applications of the gas chromatography carried out at the Junta de Energia Nuclear, Spain. Arapter VIII only includes the investigations carried out from January 1969 to December 1971. Previous investigations in this field has been published elsewhere. (Author)

Inter-laboratory comparison of elemental analysis and gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS). Part I: delta13C measurements of selected compounds for the development of an isotopic Grob-test.

Science.gov (United States)

Serra, F; Janeiro, A; Calderone, G; Rojas, J M Moreno; Rhodes, C; Gonthier, L A; Martin, F; Lees, M; Mosandl, A; Sewenig, S; Hener, U; Henriques, B; Ramalho, L; Reniero, F; Teixeira, A J; Guillou, C

2007-03-01

This study was directed towards investigating suitable compounds to be used as stable isotope reference materials for gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS) calibration. Several compounds were selected from those used in the 'Grob-test' mixture. Oxygen- and nitrogen-containing substances were added to these compounds to allow the mixture to be used as a possible multi-isotopic calibration tool for 2H/1H, 13C/12C, 15N/14N and 18O/16O ratio determinations. In this paper we present the results of delta13C measurements performed by the consortium of the five laboratories taking part in this inter-calibration exercise. All the compounds were individually assessed for homogeneity, short-term stability and long-term stability by means of EA-IRMS, as required by the bureau communitaire de reference (BCR) Guide for Production of Certified Reference Materials. The results were compared then with the GC-C-IRMS measurements using both polar and non-polar columns, and the final mixture of selected compounds underwent a further certification exercise assessing limits of accuracy and reproducibility under specified GC-C-IRMS conditions. Copyright 2007 John Wiley & Sons, Ltd.

Collaborative trial validation study of two methods, one based on high performance liquid chromatography-tandem mass spectrometry and on gas chromatography-mass spectrometry for the determination of acrylamide in bakery and potato products.

Science.gov (United States)

Wenzl, Thomas; Karasek, Lubomir; Rosen, Johan; Hellenaes, Karl-Erik; Crews, Colin; Castle, Laurence; Anklam, Elke

2006-11-03

A European inter-laboratory study was conducted to validate two analytical procedures for the determination of acrylamide in bakery ware (crispbreads, biscuits) and potato products (chips), within a concentration range from about 20 microg/kg to about 9000 microgg/kg. The methods are based on gas chromatography-mass spectrometry (GC-MS) of the derivatised analyte and on high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) of native acrylamide. Isotope dilution with isotopically labelled acrylamide was an integral part of both methods. The study was evaluated according to internationally accepted guidelines. The performance of the HPLC-MS/MS method was found to be superior to that of the GC-MS method and to be fit-for-the-purpose.

Mixed-mode chromatography/isotope ratio mass spectrometry.

Science.gov (United States)

McCullagh, James S O

2010-03-15

Liquid chromatography coupled to molecular mass spectrometry (LC/MS) has been a standard technique since the early 1970s but liquid chromatography coupled to high-precision isotope ratio mass spectrometry (LC/IRMS) has only been available commercially since 2004. This development has, for the first time, enabled natural abundance and low enrichment delta(13)C measurements to be applied to individual analytes in aqueous mixtures creating new opportunities for IRMS applications, particularly for the isotopic study of biological molecules. A growing number of applications have been published in a range of areas including amino acid metabolism, carbohydrates studies, quantification of cellular and plasma metabolites, dietary tracer and nucleic acid studies. There is strong potential to extend these to new compounds and complex matrices but several challenges face the development of LC/IRMS methods. To achieve accurate isotopic measurements, HPLC separations must provide baseline-resolution between analyte peaks; however, the design of current liquid interfaces places severe restrictions on compatible flow rates and in particular mobile phase compositions. These create a significant challenge on which reports associated with LC/IRMS have not previously focused. Accordingly, this paper will address aspects of chromatography in the context of LC/IRMS, in particular focusing on mixed-mode separations and their benefits in light of these restrictions. It aims to provide an overview of mixed-mode stationary phases and of ways to improve high aqueous separations through manipulation of parameters such as column length, temperature and mobile phase pH. The results of several practical experiments are given using proteogenic amino acids and nucleosides both of which are of noted importance in the LC/IRMS literature. This communication aims to demonstrate that mixed-mode stationary phases provide a flexible approach given the constraints of LC/IRMS interface design and acts as a

Stable isotopes and biomarkers in microbial ecology

NARCIS (Netherlands)

Boschker, H.T.S.; Middelburg, J.J.

2002-01-01

The use of biomarkers in combination with stable isotope analysis is a new approach in microbial ecology and a number of papers on a variety of subjects have appeared. We will first discuss the techniques for analysing stable isotopes in biomarkers, primarily gas chromatography-combustion-isotope

Normalization of natural gas composition data measured by gas chromatography

International Nuclear Information System (INIS)

Milton, Martin J T; Harris, Peter M; Brown, Andrew S; Cowper, Chris J

2009-01-01

The composition of natural gas determined by gas chromatography is routinely used as the basis for calculating physico-chemical properties of the gas. Since the data measured by gas chromatography have particular statistical properties, the methods used to determine the composition can make use of a priori assumptions about the statistical model for the data. We discuss a generalized approach to determining the composition, and show that there are particular statistical models for the data for which the generalized approach reduces to the widely used method of post-normalization. We also show that the post-normalization approach provides reasonable estimates of the composition for cases where it cannot be shown to arise rigorously from the statistical structure of the data

Online Stable Isotope Analysis of Dissolved Organic Carbon Size Classes Using Size Exclusion Chromatography Coupled to an Isotope Ratio Mass Spectrometer

Digital Repository Service at National Institute of Oceanography (India)

Malik, A.; Scheibe, A.; LokaBharathi, P.A.; Gleixner, G.

size classes by coupling high-performance liquid chromatography (HPLC) - size exclusion chromatography (SEC) to online isotope ratio mass spectrometry (IRMS). This represents a significant methodological contribution to DOC research. The interface...

Recent applications of gas chromatography with high-resolution mass spectrometry.

Science.gov (United States)

Špánik, Ivan; Machyňáková, Andrea

2018-01-01

Gas chromatography coupled to high-resolution mass spectrometry is a powerful analytical method that combines excellent separation power of gas chromatography with improved identification based on an accurate mass measurement. These features designate gas chromatography with high-resolution mass spectrometry as the first choice for identification and structure elucidation of unknown volatile and semi-volatile organic compounds. Gas chromatography with high-resolution mass spectrometry quantitative analyses was previously focused on the determination of dioxins and related compounds using magnetic sector type analyzers, a standing requirement of many international standards. The introduction of a quadrupole high-resolution time-of-flight mass analyzer broadened interest in this method and novel applications were developed, especially for multi-target screening purposes. This review is focused on the development and the most interesting applications of gas chromatography coupled to high-resolution mass spectrometry towards analysis of environmental matrices, biological fluids, and food safety since 2010. The main attention is paid to various approaches and applications of gas chromatography coupled to high-resolution mass spectrometry for non-target screening to identify contaminants and to characterize the chemical composition of environmental, food, and biological samples. The most interesting quantitative applications, where a significant contribution of gas chromatography with high-resolution mass spectrometry over the currently used methods is expected, will be discussed as well. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Isotope dilution analysis for urinary fentanyl and its main metabolite, norfentanyl, in patients by isotopic fractionation using capillary gas chromatography

Energy Technology Data Exchange (ETDEWEB)

Sera, Shoji; Goromaru, Tsuyoshi [Fukuyama Univ., Hiroshima (Japan). Faculty of Pharmacy and Pharmaceutical Sciences; Sameshima, Teruko; Kawasaki, Koichi; Oda, Toshiyuki

1998-07-01

Isotope dilution analysis was applied to determine urinary excretion of fentanyl (FT) and its main metabolite, norfentanyl (Nor-FT), by isotopic fractionation using a capillary gas chromatograph equipped with a surface ionization detector (SID). Urinary FT was determined quantitatively in the range of 0.4-40 ng/ml using deuterium labeled FT (FT-{sup 2}H{sub 19}), as an internal standard. We also performed isotope dilution analysis of Nor-FT in urine. N-Alkylation was necessary to sensitively detect Nor-FT with SID. Methyl derivative was selected from 3 kinds of N-alkyl derivatives to increase sensitivity and peak resolution, and to prevent interference with urinary compound. Nor-FT concentration was quantitatively determined in the range of 10-400 ng/ml using deuterium labeled Nor-FT (Nor-FT-{sup 2}H{sub 10}). No endogenous compounds or concomitant drugs interfered with the detection of FT and Nor-FT in the urine of patients. The present method will be useful for pharmacokinetic studies and the evaluation of drug interactions in FT metabolism. (author)

Isotope dilution analysis for urinary fentanyl and its main metabolite, norfentanyl, in patients by isotopic fractionation using capillary gas chromatography

International Nuclear Information System (INIS)

Sera, Shoji; Goromaru, Tsuyoshi; Sameshima, Teruko; Kawasaki, Koichi; Oda, Toshiyuki

1998-01-01

Isotope dilution analysis was applied to determine urinary excretion of fentanyl (FT) and its main metabolite, norfentanyl (Nor-FT), by isotopic fractionation using a capillary gas chromatograph equipped with a surface ionization detector (SID). Urinary FT was determined quantitatively in the range of 0.4-40 ng/ml using deuterium labeled FT (FT- 2 H 19 ), as an internal standard. We also performed isotope dilution analysis of Nor-FT in urine. N-Alkylation was necessary to sensitively detect Nor-FT with SID. Methyl derivative was selected from 3 kinds of N-alkyl derivatives to increase sensitivity and peak resolution, and to prevent interference with urinary compound. Nor-FT concentration was quantitatively determined in the range of 10-400 ng/ml using deuterium labeled Nor-FT (Nor-FT- 2 H 10 ). No endogenous compounds or concomitant drugs interfered with the detection of FT and Nor-FT in the urine of patients. The present method will be useful for pharmacokinetic studies and the evaluation of drug interactions in FT metabolism. (author)

Comparison of ultra high performance supercritical fluid chromatography, ultra high performance liquid chromatography, and gas chromatography for the separation of synthetic cathinones.

Science.gov (United States)

Carnes, Stephanie; O'Brien, Stacey; Szewczak, Angelica; Tremeau-Cayel, Lauriane; Rowe, Walter F; McCord, Bruce; Lurie, Ira S

2017-09-01

A comparison of ultra high performance supercritical fluid chromatography, ultra high performance liquid chromatography, and gas chromatography for the separation of synthetic cathinones has been conducted. Nine different mixtures of bath salts were analyzed in this study. The three different chromatographic techniques were examined using a general set of controlled synthetic cathinones as well as a variety of other synthetic cathinones that exist as positional isomers. Overall 35 different synthetic cathinones were analyzed. A variety of column types and chromatographic modes were examined for developing each separation. For the ultra high performance supercritical fluid chromatography separations, analyses were performed using a series of Torus and Trefoil columns with either ammonium formate or ammonium hydroxide as additives, and methanol, ethanol or isopropanol organic solvents as modifiers. Ultra high performance liquid chromatographic separations were performed in both reversed phase and hydrophilic interaction chromatographic modes using SPP C18 and SPP HILIC columns. Gas chromatography separations were performed using an Elite-5MS capillary column. The orthogonality of ultra high performance supercritical fluid chromatography, ultra high performance liquid chromatography, and gas chromatography was examined using principal component analysis. For the best overall separation of synthetic cathinones, the use of ultra high performance supercritical fluid chromatography in combination with gas chromatography is recommended. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gas Chromatography-Mass Spectroscopic (GC-MS) Analysis of n ...

African Journals Online (AJOL)

tuber-regium (synonym Pleurotus tuber regium) using gas chromatography-mass spectroscopic (GC-. MS) techniques. Methods: The n-hexane extract of the sclerotia ... Soxhlet extraction and analysed using gas chromatography-mass spectroscopic (MS) techniques. ..... Phytochemical composition of Pleurotus tuber regium.

Gas chromatography: mass selective detector

International Nuclear Information System (INIS)

Lapinskas, R.

1988-01-01

The mechanism of mass spectrometry technique directed for detecting molecular structures is described, with some considerations about its operational features. This mass spectrometer is used as a gas chromatography detector. (author)

Simultaneous analysis of polychlorinated biphenyls and polychlorinated naphthalenes by isotope dilution comprehensive two-dimensional gas chromatography high-resolution time-of-flight mass spectrometry

International Nuclear Information System (INIS)

Xia, Dan; Gao, Lirong; Zheng, Minghui; Wang, Shasha; Liu, Guorui

2016-01-01

Polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs) are listed as persistent organic pollutants (POPs) under the Stockholm Convention. Because they have similar physical and chemical properties, they are coeluted and are usually analyzed separately by different gas chromatography high-resolution mass spectrometry (GC-HRMS) methods. In this study, a novel method was developed for simultaneous analysis of six indicator PCBs, 12 dioxin-like PCBs, and 16 PCNs using isotope dilution comprehensive two-dimensional gas chromatography with high-resolution time-of-flight mass spectrometry (GC × GC-HRTOF-MS). The method parameters, including the type of GC column, oven temperature program, and modulation period, were systematically optimized. Complete separation of all target analytes and the matrix was achieved with a DB-XLB column in the first dimension and a BPX-70 column in the second dimension. The isotope dilution method was used for quantification of the PCBs and PCNs by GC × GC-HRTOF-MS. The method showed good linearity from 5 to 500 pg μL"−"1 for all the target compounds. The instrumental limit of detection ranged from 0.03 to 0.3 pg μL"−"1 for the 18 PCB congeners and from 0.09 to 0.6 pg μL"−"1 for the 16 PCN congeners. Repeatability for triplicate injections was always lower than 20%. The method was successfully applied to the determination of 18 PCBs present at 0.9–2054 pg g"−"1 and 16 PCNs present at 0.2–15.7 pg g"−"1 in three species of fish. The GC × GC-HRTOF-MS results agreed with those obtained by GC-HRMS. The GC × GC-HRTOF-MS method proved to be a sensitive and accurate technique for simultaneous analysis of the selected PCBs and PCNs. With the excellent chromatographic separation offered by GC × GC and accurate mass measurements offered by HRTOF-MS, this method allowed identification of non-target contaminants in the fish samples, including organochlorine pesticides and polycyclic aromatic

Simultaneous analysis of polychlorinated biphenyls and polychlorinated naphthalenes by isotope dilution comprehensive two-dimensional gas chromatography high-resolution time-of-flight mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Xia, Dan [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); University of Chinese Academy of Sciences, Beijing 100085 (China); Gao, Lirong, E-mail: gaolr@rcees.ac.cn [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Zheng, Minghui; Wang, Shasha; Liu, Guorui [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China)

2016-09-21

Polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs) are listed as persistent organic pollutants (POPs) under the Stockholm Convention. Because they have similar physical and chemical properties, they are coeluted and are usually analyzed separately by different gas chromatography high-resolution mass spectrometry (GC-HRMS) methods. In this study, a novel method was developed for simultaneous analysis of six indicator PCBs, 12 dioxin-like PCBs, and 16 PCNs using isotope dilution comprehensive two-dimensional gas chromatography with high-resolution time-of-flight mass spectrometry (GC × GC-HRTOF-MS). The method parameters, including the type of GC column, oven temperature program, and modulation period, were systematically optimized. Complete separation of all target analytes and the matrix was achieved with a DB-XLB column in the first dimension and a BPX-70 column in the second dimension. The isotope dilution method was used for quantification of the PCBs and PCNs by GC × GC-HRTOF-MS. The method showed good linearity from 5 to 500 pg μL{sup −1} for all the target compounds. The instrumental limit of detection ranged from 0.03 to 0.3 pg μL{sup −1} for the 18 PCB congeners and from 0.09 to 0.6 pg μL{sup −1} for the 16 PCN congeners. Repeatability for triplicate injections was always lower than 20%. The method was successfully applied to the determination of 18 PCBs present at 0.9–2054 pg g{sup −1} and 16 PCNs present at 0.2–15.7 pg g{sup −1} in three species of fish. The GC × GC-HRTOF-MS results agreed with those obtained by GC-HRMS. The GC × GC-HRTOF-MS method proved to be a sensitive and accurate technique for simultaneous analysis of the selected PCBs and PCNs. With the excellent chromatographic separation offered by GC × GC and accurate mass measurements offered by HRTOF-MS, this method allowed identification of non-target contaminants in the fish samples, including organochlorine pesticides and

Gas chromatography

International Nuclear Information System (INIS)

Cram, S.P.; Risby, T.H.; Field, L.R.; Yu, W.L.

1980-01-01

In addition to the published literature for the years 1978 - 79, this review of developments in the field of gas chromatography includes earlier articles of particular significance appearing in foreign journals and the patent literature which was not available at the time of the previous review. The articles cited were selected as presenting the most fundamental developments in theory, methodology, and instrumentation. Some applications are cited if they reflect an advance in the state-of-the-art or have particular relevance to new developments. 1149 references are cited

21 CFR 862.2250 - Gas liquid chromatography system for clinical use.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Gas liquid chromatography system for clinical use... Instruments § 862.2250 Gas liquid chromatography system for clinical use. (a) Identification. A gas liquid chromatography system for clinical use is a device intended to separate one or more drugs or compounds from a...

Advances in Methane Isotope Measurements via Direct Absorption Spectroscopy with Applications to Oil and Gas Source Characterization

Science.gov (United States)

Yacovitch, T. I.; Herndon, S. C.; Roscioli, J. R.; Petron, G.; Shorter, J. H.; Jervis, D.; McManus, J. B.; Nelson, D. D.; Zahniser, M. S.; Kolb, C. E., Jr.

2015-12-01

Instrumental developments in the measurement of multiple isotopes of methane (12CH4, 13CH4 and 12CH3D) are presented. A first generation 8-micron instrument quantifies 12CH4 and 13CH4 at a 1-second rate via tunable infrared direct absorption spectroscopy (TILDAS). A second generation instrument uses two 3-micron intraband cascade lasers in an Aerodyne dual laser chassis for simultaneous measurement of 12CH4, 13CH4 and 12CH3D. Sensitivity and noise performance improvements are examined. The isotopic signature of methane provides valuable information for emission source identification of this greenhouse gas. A first generation spectrometer has been deployed in the field on a mobile laboratory along with a sophisticated 4-tank calibration system. Calibrations are done on an agressive schedule, allowing for the correction of measured isotope ratios to an absolute isotope scale. Distinct isotopic signatures are found for a number of emission sources in the Denver-Julesburg Basin: oil and gas gathering stations, compressor stations and processing plants; a municipal landfill, and dairy/cattle operations. The isotopic signatures are compared with measured ethane/methane ratios. These direct absorption measurements have larger uncertainties than samples measured via gas chromatography-mass spectrometry, but have several advantages over canister sampling methods: individual sources of short duration are easier to isolate; calibrated isotope ratio results are available immediately; replicate measurements on a single source are easily performed; and the number of sources sampled is not limited by canister availability and processing time.

Measurement of the 13C/12C ratio of soil-plant individual sugars by gas chromatography/combustion/isotope-ratio mass spectrometry of silylated derivatives.

Science.gov (United States)

Derrien, Delphine; Balesdent, Jérôme; Marol, Christine; Santaella, Catherine

2003-01-01

Carbohydrate is an important pool in the terrestrial carbon cycle. The potential offered by natural and artificial 13C-labelling techniques should therefore be applied to the investigation of the dynamics of individual sugars in soils. For this reason, we evaluated the method of 13C sugar analysis by gas chromatography/combustion/isotope-ratio mass spectrometry (GC/C/IRMS) after hydrolysis and direct trimethylsilylation. Trimethylsilylation involved the addition of several carbon atoms per sugar. These atoms have to be taken into account in the estimation of the carbon isotope ratio. The analysis of standard and natural pentoses and hexoses of known 13C enrichments revealed that the number of analysed added carbon atoms was less than expected from stoichiometry. This was attributed to incomplete derivatization and/or incomplete oxidation of methylsilyl carbon before IRMS. Using a calibration of the number of analysed added carbon atoms, the isotope excess of enriched samples could be determined with a relative error close to 5%. Concerning the determination of natural abundances by GC/C/IRMS, we could measure the delta 13C of standard C3- and C4-derived sugars with an accuracy of +/-1.5 per thousand using the previous calibration. We were able to apply this technique to plant-soil systems labelled by pulse-chase of 13CO2, revealing the nature and dynamics of sugars in the plant rhizosphere. Copyright 2003 John Wiley & Sons, Ltd.

Isotope separations using chromatographic methods

International Nuclear Information System (INIS)

Leseticky, L.

1985-01-01

A survey is given of chromatographic separations of compounds only differing in isotope composition. Isotope effects on physical properties which allow chromatographic separation (vapour tension, adsorption heat, partition coefficient) are very small, with the exception of the simplest molecules. Therefore, separation factors only assume the value of several per cent. From this ensues the necessity of using columns which are specially and very carefully prepared and have a separation efficiency of the order of 10 4 theoretical plates. Briefly discussed is liquid chromatography on ion exchangers which with a varied degree of success was used for separating simple inorganic compounds or ions. Ion exchange chromatography of amino acids labelled with tritium, and chromatography of tritium labelled steroids also provided only a certain degree of separation. A detailed analysis is presented of gas chromatography separation of various deuterium and tritium labelled low-molecular compounds, to which a number of studies has been devoted in the literature. Very promising is the method of complexation gas chromatography based on the reversible formation of a complex of the ligand (the compound being separated) and the compound of the (transition) metal as the steady-state phase. (author)

Frontal and band displacement chromatography of the hydrogen isotopes on palladium; Chromatographies frontale et de deplacement de bande des isotopes de l'hydrogene sur palladium

Energy Technology Data Exchange (ETDEWEB)

Botter, F; Menes, J; Tistchenko, S; Dirian, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

As a result of hydrogen isotope separations which we have carried out on supports containing palladium, we believe that we can now make a double contribution, theoretical and experimental, to the work which has already been published in this field. From the fundamental point of view we have developed and studied the validity of a simple model, in our particular case of a separation coefficient {alpha} which is very different to unity. This model, which is of a counter-current isotopic exchange, neglects the longitudinal diffusion in the gas phase and the lateral diffusion in the adsorbed phase and only takes into account the surface resistance to exchange between the phases. It is therefore possible to estimate the efficiency of a chromatography column in terms of the height equivalent of a theoretical plate (HETP). The slight differences observed between the actual chromatograms and the simple model justify both the research undertaken into a more complex model taking into account the diffusion, and the adoption of a simple model for comparing the efficiency of several columns. We describe also a new and simple graphical method for deducing the number of theoretical plates of a column in chromatograms of the frontal and band displacement types. Experimentally we give in particular the criteria for the validity of the model used, the law as a function of the {sup {alpha}}H{sub 2}-HD temperature, the study of the HETP as a function of the various parameters on several palladium containing supports, and the possibilities of an application to preparative chromatography. (authors) [French] Grace aux separations des isotopes de l'hydrogene que nous avons realisees sur masses palladiees, nous pensons apporter aux etudes precedemment publiees dans ce domaine, une double contribution, theorique et experimentale. Du point de vue fondamental, on a developpe et etudie la validite d'un modele simple, dans notre cas particulier d'un coefficient de separation {alpha} tres

Gas chromatography/isotope ratio mass spectrometry: analysis of methanol, ethanol and acetic acid by direct injection of aqueous alcoholic and acetic acid samples.

Science.gov (United States)

Ai, Guomin; Sun, Tong; Dong, Xiuzhu

2014-08-15

Methanol, ethanol, and acetic acid are not easily extracted from aqueous samples and are susceptible to isotope fractionation in gas chromatography/isotope ratio mass spectrometry (GC/IRMS) analysis. Developing a direct dilution GC/IRMS method for aqueous samples, by adjusting the sample concentrations in common solvents to be similar to each other and using a fixed GC split ratio, is very convenient and important because any linearity effects caused by amount-dependent isotope fractionation can be avoided. The suitability of acetonitrile and acetone solvents for the GC/IRMS analysis of pure methanol, ethanol and acetic acid, and commercial liquor and vinegar samples was evaluated using n-hexane and water as control solvents. All the solvents including water were separated from the analyte on a HP-INNOWAX column and were diverted away from the combustion interface. The influence of liquor matrix on the ethanol GC/IRMS analyses was evaluated by adding pure ethanol to liquor samples. Acetonitrile and acetone gave similar δ(13) C values for pure ethanol and pure acetic acid to those obtained in water and n-hexane, and also gave similar δ(13) C values of ethanol in liquor and acetic acid in white vinegar to that obtained in water. For methanol analysis, acetonitrile and refined acetone gave similar δ(13) C values to that obtained in water, but n-hexane was not a suitable solvent. In addition, isotopic fractionation caused by solvent and solute interactions was observed. We recommend using acetonitrile for the GC/IRMS analysis of aqueous alcoholic samples, and acetone for the analysis of aqueous acetic acid samples. This direct dilution method can provide high accurate and precise GC/IRMS analysis of the relative changes in δ(13) C values of methanol, ethanol, and acetic acid. Copyright © 2014 John Wiley & Sons, Ltd.

A versatile method for simultaneous stable carbon isotope analysis of DNA and RNA nucleotides by liquid chromatography/isotope ratio mass spectrometry

NARCIS (Netherlands)

Moerdijk-Poortvliet, T.C.W.; Brasser, J.; de Ruiter, G.; Houtekamer, M.; Bolhuis, H.; Stal, L.J.; Boschker, H.T.S.

2014-01-01

RATIONALELiquid chromatography/isotope ratio mass spectrometry (LC/IRMS) is currently the most accurate and precise technique for the measurement of compound-specific stable carbon isotope ratios (C-13/C-12) in biological metabolites, at their natural abundance. However, until now this technique

On the interference of Kr during carbon isotope analysis of methane using continuous-flow combustion–isotope ratio mass spectrometry

NARCIS (Netherlands)

Schmitt, J.; Seth, B.; Bock, M; van der Veen, C.; Möller, L.; Sapart, C.J.; Prokopiou, M.; Sowers, T.; Röckmann, T.; Fischer, H

2013-01-01

Stable carbon isotope analysis of methane ( 13C of CH4) on atmospheric samples is one key method to constrain the current and past atmospheric CH4 budget. A frequently applied measurement technique is gas chromatography (GC) isotope ratio mass spectrometry (IRMS) coupled to a

Suitability of selected free-gas and dissolved-gas sampling containers for carbon isotopic analysis.

Science.gov (United States)

Eby, P; Gibson, J J; Yi, Y

2015-07-15

Storage trials were conducted for 2 to 3 months using a hydrocarbon and carbon dioxide gas mixture with known carbon isotopic composition to simulate typical hold times for gas samples prior to isotopic analysis. A range of containers (both pierced and unpierced) was periodically sampled to test for δ(13)C isotopic fractionation. Seventeen containers were tested for free-gas storage (20°C, 1 atm pressure) and 7 containers were tested for dissolved-gas storage, the latter prepared by bubbling free gas through tap water until saturated (20°C, 1 atm) and then preserved to avoid biological activity by acidifying to pH 2 with phosphoric acid and stored in the dark at 5°C. Samples were extracted using valves or by piercing septa, and then introduced into an isotope ratio mass spectrometer for compound-specific δ(13)C measurements. For free gas, stainless steel canisters and crimp-top glass serum bottles with butyl septa were most effective at preventing isotopic fractionation (pierced and unpierced), whereas silicone and PTFE-butyl septa allowed significant isotopic fractionation. FlexFoil and Tedlar bags were found to be effective only for storage of up to 1 month. For dissolved gas, crimp-top glass serum bottles with butyl septa were again effective, whereas silicone and PTFE-butyl were not. FlexFoil bags were reliable for up to 2 months. Our results suggest a range of preferred containers as well as several that did not perform very well for isotopic analysis. Overall, the results help establish better QA/QC procedures to avoid isotopic fractionation when storing environmental gas samples. Recommended containers for air transportation include steel canisters and glass serum bottles with butyl septa (pierced and unpierced). Copyright © 2015 John Wiley & Sons, Ltd.

ISOFORMAL: isotopic tracing of formaldehyde sources in housing. Intermediary report

International Nuclear Information System (INIS)

2011-01-01

The authors report an investigation which comprised a sampling and a chemical and isotopic analysis of emissions from the main indoor formaldehyde pollution sources in order to create a exhaustive database. Emissions which are characteristic of motorcar traffic, are also sampled in order to asses their possible contribution in the housing air. This step will be used to develop emission simulations of formaldehyde sources in a laboratory-house in order to validate the isotopic approach as tracing tool for sources of this compound. The report describes the carbon and hydrogen steady isotopes. It presents the sampling procedure, reports the determination of formaldehyde concentrations by high performance liquid chromatography with UV detectors, the use of gas source mass spectrometry, and the analytic development of the isotopic analysis of formaldehyde by gas chromatography combustion isotope ratio mass spectrometry. Outdoor and indoor pollution sources are discussed

Multi-column chromatography and the use of isotopes in the study of steroid metabolism

International Nuclear Information System (INIS)

Sayegh, J.F.; Vestergaard, P.

1978-01-01

Multi-column liquid chromatography is demonstrated to be a technique well suited for isotope experiments involving administration of labelled cortisol. It has potential for secretion rate determinations, for dynamic studies of cortisol metabolism and for work with stable isotopes. (author)

Detection of Synthetic Testosterone Use by Novel Comprehensive Two-Dimensional Gas Chromatography Combustion Isotope Ratio Mass Spectrometry (GC×GCC-IRMS)

Science.gov (United States)

Tobias, Herbert J.; Zhang, Ying; Auchus, Richard J.; Brenna, J. Thomas

2011-01-01

We report the first demonstration of Comprehensive Two-dimensional Gas Chromatography Combustion Isotope Ratio Mass Spectrometry (GC×GCC-IRMS) for the analysis of urinary steroids to detect illicit synthetic testosterone use, of interest in sport doping. GC coupled to IRMS (GCC-IRMS) is currently used to measure the carbon isotope ratios (CIR, δ13C) of urinary steroids in anti-doping efforts; however, extensive cleanup of urine extracts is required prior to analysis to enable baseline separation of target steroids. With its greater separation capabilities, GC×GC has the potential to reduce sample preparation requirements and enable CIR analysis of minimally processed urine extracts. Challenges addressed include on-line reactors with minimized dimensions to retain narrow peaks shapes, baseline separation of peaks in some cases, and reconstruction of isotopic information from sliced steroid chromatographic peaks. Difficulties remaining include long-term robustness of on-line reactors and urine matrix effects that preclude baseline separation and isotopic analysis of low concentration and trace components. In this work, steroids were extracted, acetylated, and analyzed using a refined, home-built GC×GCC-IRMS system. 11-hydroxy-androsterone (11OHA) and 11-ketoetiocolanolone (11KE) were chosen as endogenous reference compounds (ERC) because of their satisfactory signal intensity, and their CIR was compared to target compounds (TC) androsterone (A) and etiocholanolone (E). Separately, a GC×GC-qMS system was used to measure testosterone (T)/EpiT concentration ratios. Urinary extracts of urine pooled from professional athletes, and urine from one individual that received testosterone gel (T-gel) and one individual that received testosterone injections (T-shot) were analyzed. The average precisions of δ13C and Δδ13C measurements were SD(δ13C) approximately ± 1‰ (n=11). The T-shot sample resulted in a positive for T use with a T/EpiT ratio of > 9 and CIR

Use of micro gas chromatography in the fuel cycle of fusion reactors

International Nuclear Information System (INIS)

Laesser, R.; Gruenhagen, S.; Kawamura, Y.

2003-01-01

Various analytical techniques exist to determine the compositions of gases handled in the fuel cycle of future fusion machines. Gas chromatography was found to be the most appropriate method. The main disadvantages of conventional gas chromatography were the long retention times for the heavy hydrogen species of >30 min. Recent progress in the development of micro-gas chromatography has reduced these retention times to ∼3 min. The usefulness of micro-gas chromatography for the analysis of hydrogen and impurity gas mixtures in the fuel cycle of future fusion machines is presented and the advantages and drawbacks are discussed

Data acquisition and quantitative analysis of stable hydrogen isotope in liquid and gas in the liquid phase catalytic exchange process

International Nuclear Information System (INIS)

Choi, H. J.; Lee, H. S.; Kim, K. R.; Cheong, H. S.; Ahn, D. H.; Lee, S. H.; Paek, S. W.; Kang, H. S.; Kim, J. G.

2001-01-01

A pilot plant for the Liquid Phase Catalytic Exchange process was built and has been operating to test the hydrophobic catalyst developed to remove the tritium generated at the CANDU nuclear power plants. The methods of quantitative analysis of hydrogen stable isotope were compared. Infrared spectroscopy was used for the liquid samples, and gas chromatography with hydrogen carrier gas showed the best result for gas samples. Also, a data acquisition system was developed to record the operation parameters. This record was very useful to investigate the causes of the system trip

Optimization of an online heart-cutting multidimensional gas chromatography clean-up step for isotopic ratio mass spectrometry and simultaneous quadrupole mass spectrometry measurements of endogenous anabolic steroid in urine.

Science.gov (United States)

Casilli, Alessandro; Piper, Thomas; de Oliveira, Fábio Azamor; Padilha, Monica Costa; Pereira, Henrique Marcelo; Thevis, Mario; de Aquino Neto, Francisco Radler

2016-11-01

Measuring carbon isotope ratios (CIRs) of urinary analytes represents a cornerstone of doping control analysis and has been particularly optimized for the detection of the misuse of endogenous steroids. Isotope ratio mass spectrometry (IRMS) of appropriate quality, however, necessitates adequate purities of the investigated steroids, which requires extensive pre-analytical sample clean-up steps due to both the natural presence of the target analytes and the high complexity of the matrix. In order to accelerate the sample preparation and increase the automation of the process, the use of multidimensional gas chromatography (MDGC) prior to IRMS experiments, was investigated. A well-established instrumental configuration based on two independent GC ovens and one heart-cutting device was optimized. The first dimension (1D) separation was obtained by a non-polar column which assured high efficiency and good loading capacity, while the second dimension (2D), based on a mid-polar stationary phase, provided good selectivity. A flame ionization detector monitored the 1D, and the 2D was simultaneously recorded by isotope ratio and quadrupole mass spectrometry. The assembled MDGC set-up was applied for measuring testosterone, 5α- and 5β-androstanediol, androsterone, and etiocholanolone as target compounds and pregnanediol as endogenous reference compound. The urine sample were pretreated by conventional sample preparation steps comprising solid-phase extraction, hydrolysis, and liquid-liquid extraction. The extract obtained was acetylated and different aliquots were injected into the MDGC system. Two high performance liquid chromatography steps, conventionally adopted prior to CIR measurements, were replaced by the MDGC approach. The obtained values were consistent with the conventional ones. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Multiplex gas chromatography

Science.gov (United States)

Valentin, Jose R.

1990-01-01

The principles of the multiplex gas chromatography (GC) technique, which is a possible candidate for chemical analysis of planetary atmospheres, are discussed. Particular attention is given to the chemical modulators developed by present investigators for multiplex GC, namely, the thermal-desorption, thermal-decomposition, and catalytic modulators, as well as to mechanical modulators. The basic technique of multiplex GC using chemical modulators and a mechanical modulator is demonstrated. It is shown that, with the chemical modulators, only one gas stream consisting of the carrier in combination with the components is being analyzed, resulting in a simplified instrument that requires relatively few consumables. The mechanical modulator demonstrated a direct application of multiplex GC for the analysis of gases in atmosphere of Titan at very low pressures.

Stable Chlorine Isotopes and Elemental Chlorine by Thermal Ionization Mass Spectrometry and Ion Chromatography; Martian Meteorites, Carbonaceous Chondrites and Standard Rocks

Science.gov (United States)

Nakamura, N.; Nyquist, L. E.; Reese, Y.; Shih, C.-Y.; Fujitani, T.; Okano, O.

2011-01-01

Recently significantly large mass fractionation of stable chlorine isotopes has been reported for terrestrial and lunar samples [1,2]. In addition, in view of possible early solar system processes [3] and also potential perchlorate-related fluid/microbial activities on the Martian surface [4,5], a large chlorine isotopic fractionation might be expected for some types of planetary materials. Due to analytical difficulties of isotopic and elemental analyses, however, current chlorine analyses for planetary materials are controversial among different laboratories, particularly between IRMS (gas source mass spectrometry) and TIMS (Thermal Ionization Mass Spectrometry) groups [i.e. 1,6,7] for isotopic analyses, as well as between those doing pyrohydrolysis and other groups [i.e. 6,8]. Additional careful investigations of Cl isotope and elemental abundances are required to confirm real chlorine isotope and elemental variations for planetary materials. We have developed a TIMS technique combined with HF-leaching/ion chromatography at NASA JSC that is applicable to analysis of small amounts of meteoritic and planetary materials. We present here results for several standard rocks and meteorites, including Martian meteorites.

Simultaneous Detection of Androgen and Estrogen Abuse in Breeding Animals by Gas Chromatography-Mass Spectrometry/Combustion/Isotope Ratio Mass Spectrometry (GC-MS/C/IRMS) Evaluated against Alternative Methods.

Science.gov (United States)

Janssens, Geert; Mangelinckx, Sven; Courtheyn, Dirk; De Kimpe, Norbert; Matthijs, Bert; Le Bizec, Bruno

2015-09-02

The administration of synthetic homologues of naturally occurring steroids can be demonstrated by measuring (13)C/(12)C isotopic ratios of their urinary metabolites. Gas chromatography-mass spectrometry/combustion/isotope ratio mass spectrometry (GC-MS/C/IRMS) was used in this study to appraise in a global approach isotopic deviations of two 17β-testosterone metabolites (17α-testosterone and etiocholanolone) and one 17β-estradiol metabolite (17α-estradiol) together with those of 5-androstene-3β,17α-diol as endogenous reference compound (ERC). Intermediate precisions of 0.35‰, 1.05‰, 0.35‰, and 0.21‰, respectively, were observed (n = 8). To assess the performance of the analytical method, a bull and a heifer were treated with 17β-testosterone propionate and 17β-estradiol-3-benzoate. The sensitivity of the method permitted the demonstration of 17β-estradiol treatment up to 24 days. For 17β-testosterone treatment, the detection windows were 3 days and 24 days for the bull and the heifer, respectively. The capability of GC-MS/C/IRMS to demonstrate natural steroid abuse for urinary steroids was eventually compared to those of mass spectrometry (LC-MS/MS) when measuring intact steroid esters in blood and hair.

Characteristics of stable carbon isotopic composition of shale gas

Directory of Open Access Journals (Sweden)

Zhenya Qu

2016-04-01

Full Text Available A type Ⅱ kerogen with low thermal maturity was adopted to perform hydrocarbon generation pyrolysis experiments in a vacuum (Micro-Scale Sealed Vessel system at the heating rates of 2 °C/h and 20 °C/h. The stable carbon isotopic compositions of gas hydrocarbons were measured to investigate their evolving characteristics and the possible reasons for isotope reversal. The δ13C values of methane became more negative with the increasing pyrolysis temperatures until it reached the lightest point, after which they became more positive. Meanwhile, the δ13C values of ethane and propane showed a positive trend with elevating pyrolysis temperatures. The carbon isotopic compositions of shale gasses were mainly determined by the type of parent organic matter, thermal evolutionary extent, and gas migration in shale systems. Our experiments and study proved that the isotope reversal shouldn't occur in a pure thermogenic gas reservoir, it must be involved with some other geochemical process/es; although mechanisms responsible for the reversal are still vague. Carbon isotopic composition of the Fayetteville and Barnett shale gas demonstrated that the isotope reversal was likely involved with water–gas reaction and Fischer-Tropsch synthesis during its generation.

Stable isotope ratiometer-multiple ion detector (SIRMID) unit for quantitative and qualitative stable isotope studies by gas chromatography-mass spectrometry

International Nuclear Information System (INIS)

Klein, P.D.; Haumann, J.R.; Hachey, D.L.

1975-01-01

A stable isotope ratiometer-multiple ion detector (SIRMID) unit which can drive existing gas chromatograph-quadrupole or magnetic sector mass spectrometers to monitor up to six ions in turn is described. Each of the three pairs of ions can be selected for quantitation; thus three different or successive components can be analyzed in a single GC run. A background subtraction option permits the ion intensity in the absence of sample to be subtracted automatically during sample measurement. Displays of accumulated counts and isotope ratio are updated twice per second during the measurement and can be printed out at its conclusion. All six ions can be monitored in the analog mode by parallel outputs to a multipen recorder. Experience gained in the construction of this prototype indicates that SIRMID units could be commercially available for $10K, or about 1 / 3 rd to 1 / 6 th of the cost of even an inexpensive computer system. (U.S.)

Quantification of fentanyl in serum by isotope dilution analysis using capillary gas chromatography

Energy Technology Data Exchange (ETDEWEB)

Sera, Shoji; Goromaru, Tsuyoshi [Fukuyama Univ., Hiroshima (Japan); Sameshima, Teruko; Kawasaki, Koichi; Oda, Toshiyuki

1998-06-01

The quantitative determination of fentanyl (FT) in serum was examined by isotope dilution analysis using a capillary gas chromatograph equipped with a surface ionization detector. The separation of FT and its deuterated analogue, FT-{sup 2}H{sub 19}, was achieved within 15 min a column temperature of 260degC by using a 25 m column. Measurement of the samples prepared by the addition of a known amount of FT in the range of 0.2 to 40 ng/ml with 20 ng/ml of FT-{sup 2}H{sub 19} to human control serum allowed observation of a linear relationship between the peak area ratio and the added amount ratio. The correlation coefficient obtained by regression analysis was 0.999. The advantage of the present isotope dilution method was demonstrated by comparison with other FT analogues which substituted a propionyl group with an acetyl group or a phenethyl group with a benzyl group as the internal standard. The present method was used to determine the serum level of FT in surgical patients after i.v. administration. No endogenous compounds and concomitant drugs interfered with the detection of FT or FT-{sup 2}H{sub 19}. This method was considered to be useful for the pharmacokinetic study of FT in patients. (author)

Quantification of fentanyl in serum by isotope dilution analysis using capillary gas chromatography

International Nuclear Information System (INIS)

Sera, Shoji; Goromaru, Tsuyoshi; Sameshima, Teruko; Kawasaki, Koichi; Oda, Toshiyuki

1998-01-01

The quantitative determination of fentanyl (FT) in serum was examined by isotope dilution analysis using a capillary gas chromatograph equipped with a surface ionization detector. The separation of FT and its deuterated analogue, FT- 2 H 19 , was achieved within 15 min a column temperature of 260degC by using a 25 m column. Measurement of the samples prepared by the addition of a known amount of FT in the range of 0.2 to 40 ng/ml with 20 ng/ml of FT- 2 H 19 to human control serum allowed observation of a linear relationship between the peak area ratio and the added amount ratio. The correlation coefficient obtained by regression analysis was 0.999. The advantage of the present isotope dilution method was demonstrated by comparison with other FT analogues which substituted a propionyl group with an acetyl group or a phenethyl group with a benzyl group as the internal standard. The present method was used to determine the serum level of FT in surgical patients after i.v. administration. No endogenous compounds and concomitant drugs interfered with the detection of FT or FT- 2 H 19 . This method was considered to be useful for the pharmacokinetic study of FT in patients. (author)

Early stages in the history of gas chromatography.

Science.gov (United States)

Kolomnikov, Ivan G; Efremov, Alexander M; Tikhomirova, Tatyana I; Sorokina, Nadezhda M; Zolotov, Yury A

2018-02-16

The creation of gas chromatography is traditionally associated with the names of Nobel Prize winner Archer Martin and his colleagues Richard Synge and Anthony James. However, sometimes references to their predecessors can be found. An investigation conducted by the authors of this article not only confirmed the reliability of these references; but in fact led to the conclusion that by 1952, which is commonly believed to be the year when gas chromatography was born, many research papers had already been devoted to this method, mainly, in its gas-solid version. These papers are considered in this article. Copyright © 2018. Published by Elsevier B.V.

Characterisation of uremic "Middle molecular"fractions by gas chromatography mass spectrometry, isotachophoresis, and liquid chromatography

NARCIS (Netherlands)

Schoots, A.C.; Mikkers, F.E.P.; Claessens, H.A.; Smet, de R.; Landschoot, van N.; Ringoir, S.M.G.

1982-01-01

Uremic ultrafiltrates (and normal serum, for comparison) were fractionated by means of gel filtration. The collected fractions were further investigated by combined analytical techniques: "high- performance" liquid chromatography, gas chromatography, mass spectrometry, and isotachophoresis.

Calcium isotope fractionation in liquid chromatography with benzo-18-crown-6 resin in aqueous hydrobromic acid medium

International Nuclear Information System (INIS)

Sato, Takuya; Oi, Takao

2015-01-01

Liquid chromatography operated in a breakthrough mode was employed to study calcium isotope fractionation in the aqueous hydrobromic acid medium. Highly porous silica beads, the inner pores of which were embedded with a benzo-18-crown-6 ether resin, were used as column packing material. Enrichment of heavier isotopes of calcium was observed in the frontal part of respective calcium chromatograms. The values of the isotope fractionation coefficient were on the order of 10 -3 . The observed isotope fractionation coefficient was dependent on the concentration of hydrobromic acid in the calcium feed solution; a higher HBr concentration resulted in a smaller fractionation coefficient value. The present calcium isotope effects were most probably mass-dependent, indicating that they mostly came from isotope effects based on molecular vibration. Molecular orbital calculations supported the present experimental results in a qualitative fashion. Chromatography operated in aqueous HBr media is a better system of Ca isotope separation than that operated in aqueous HCl media. (author)

Flow Rates in Liquid Chromatography, Gas Chromatography and Supercritical Fluid Chromatography: A Tool for Optimization

Directory of Open Access Journals (Sweden)

Joris Meurs

2016-08-01

Full Text Available This paper aimed to develop a standalone application for optimizing flow rates in liquid chromatography (LC, gas chromatography (GC and supercritical fluid chromatography (SFC. To do so, Van Deemter’s equation, Knox’ equation and Golay’s equation were implemented in a MATLAB script and subsequently a graphical user interface (GUI was created. The application will show the optimal flow rate or linear velocity and the corresponding plate height for the set input parameters. Furthermore, a plot will be shown in which the plate height is plotted against the linear flow velocity. Hence, this application will give optimized flow rates for any set conditions with minimal effort.

ANALYSIS AND IDENTIFICATION SPIKING CHEMICAL COMPOUNDS RELATED TO CHEMICAL WEAPON CONVENTION IN UNKNOWN WATER SAMPLES USING GAS CHROMATOGRAPHY AND GAS CHROMATOGRAPHY ELECTRON IONIZATION MASS SPECTROMETRY

Directory of Open Access Journals (Sweden)

Harry Budiman

2010-06-01

Full Text Available The identification and analysis of chemical warfare agents and their degradation products is one of important component for the implementation of the convention. Nowadays, the analytical method for determination chemical warfare agent and their degradation products has been developing and improving. In order to get the sufficient analytical data as recommended by OPCW especially in Proficiency Testing, the spiking chemical compounds related to Chemical Weapon Convention in unknown water sample were determined using two different techniques such as gas chromatography and gas chromatography electron-impact ionization mass spectrometry. Neutral organic extraction, pH 11 organic extraction, cation exchanged-methylation, triethylamine/methanol-silylation were performed to extract the chemical warfare agents from the sample, before analyzing with gas chromatography. The identification of chemical warfare agents was carried out by comparing the mass spectrum of chemicals with mass spectrum reference from the OPCW Central Analytical Database (OCAD library while the retention indices calculation obtained from gas chromatography analysis was used to get the confirmation and supported data of  the chemical warfare agents. Diisopropyl methylphosphonate, 2,2-diphenyl-2-hydroacetic acid and 3-quinuclidinol were found in unknown water sample. Those chemicals were classified in schedule 2 as precursor or reactant of chemical weapons compound in schedule list of Chemical Weapon Convention.   Keywords: gas chromatography, mass spectrometry, retention indices, OCAD library, chemical warfare agents

Frontal and band displacement chromatography of the hydrogen isotopes on palladium; Chromatographies frontale et de deplacement de bande des isotopes de l'hydrogene sur palladium

Energy Technology Data Exchange (ETDEWEB)

Botter, F.; Menes, J.; Tistchenko, S.; Dirian, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

As a result of hydrogen isotope separations which we have carried out on supports containing palladium, we believe that we can now make a double contribution, theoretical and experimental, to the work which has already been published in this field. From the fundamental point of view we have developed and studied the validity of a simple model, in our particular case of a separation coefficient {alpha} which is very different to unity. This model, which is of a counter-current isotopic exchange, neglects the longitudinal diffusion in the gas phase and the lateral diffusion in the adsorbed phase and only takes into account the surface resistance to exchange between the phases. It is therefore possible to estimate the efficiency of a chromatography column in terms of the height equivalent of a theoretical plate (HETP). The slight differences observed between the actual chromatograms and the simple model justify both the research undertaken into a more complex model taking into account the diffusion, and the adoption of a simple model for comparing the efficiency of several columns. We describe also a new and simple graphical method for deducing the number of theoretical plates of a column in chromatograms of the frontal and band displacement types. Experimentally we give in particular the criteria for the validity of the model used, the law as a function of the {sup {alpha}}H{sub 2}-HD temperature, the study of the HETP as a function of the various parameters on several palladium containing supports, and the possibilities of an application to preparative chromatography. (authors) [French] Grace aux separations des isotopes de l'hydrogene que nous avons realisees sur masses palladiees, nous pensons apporter aux etudes precedemment publiees dans ce domaine, une double contribution, theorique et experimentale. Du point de vue fondamental, on a developpe et etudie la validite d'un modele simple, dans notre cas particulier d'un coefficient de separation

Simplified simulation of multicomponent isotope separation by gas centrifuge

International Nuclear Information System (INIS)

Guo Zhixiong; Ying Chuntong

1995-01-01

The expressions of diffusion equation for multicomponent isotope separation by gas centrifuge are derived by utilizing the simplified diffusion transport vector. A method of radial averaging which was restricted to a binary mixture is extended to multicomponent isotope mixtures by using an iterative scheme. A numerical analysis of tetradic UF 6 or SF 6 gas isotope separation by centrifuge is discussed when a special model of velocity distribution is given. The dependence of mutual separation factor for the components on their molecular weights' difference is obtained. Some aspects of the given model of gas fluid are also discussed

Study of radiolysis products of natural organic materials by means of gas chromatography

International Nuclear Information System (INIS)

Pogocki, D.

1994-01-01

Analytical methods based on gas chromatography for identification determination of products arising during food irradiation have been presented. Behind the classics version of the methods one has shown also combined methods being the on-line connection of gas chromatography with mass spectroscopy as well as gas chromatography with liquid chromatography and mass spectroscopy. The applicability as well as weakness and advantages of each version have been discussed on the context of food irradiation. 11 refs, 7 figs

A novel methylation derivatization method for δ(18)O analysis of individual carbohydrates by gas chromatography/pyrolysis-isotope ratio mass spectrometry.

Science.gov (United States)

Lehmann, Marco M; Fischer, Maria; Blees, Jan; Zech, Michael; Siegwolf, Rolf T W; Saurer, Matthias

2016-01-15

The oxygen isotope ratio (δ(18)O) of carbohydrates derived from animals, plants, sediments, and soils provides important information about biochemical and physiological processes, past environmental conditions, and geographical origins, which are otherwise not available. Nowadays, δ(18)O analyses are often performed on carbohydrate bulk material, while compound-specific δ(18)O analyses remain challenging and methods for a wide range of individual carbohydrates are rare. To improve the δ(18)O analysis of individual carbohydrates by gas chromatography/pyrolysis-isotope ratio mass spectrometry (GC/Pyr-IRMS) we developed a new methylation derivatization method. Carbohydrates were fully methylated within 24 h in an easy-to-handle one-pot reaction in acetonitrile, using silver oxide as proton acceptor, methyl iodide as methyl group carrier, and dimethyl sulfide as catalyst. The precision of the method ranged between 0.12 and 1.09‰ for the δ(18)O values of various individual carbohydrates of different classes (mono-, di-, and trisaccharides, alditols), with an accuracy of a similar order of magnitude, despite high variation in peak areas. Based on the δ(18)O values of the main isomers, important monosaccharides such as glucose and fructose could also be precisely analyzed for the first time. We tested the method on standard mixtures, honey samples, and leaf carbohydrates extracted from Pinus sylvestris, showing that the method is also applicable to different carbohydrate mixtures. The new methylation method shows unrivalled accuracy and precision for δ(18)O analysis of various individual carbohydrates; it is fast and easy-to-handle, and may therefore find wide-spread application. Copyright © 2015 John Wiley & Sons, Ltd.

Device to remove hydrogen isotopes from a gas phase

International Nuclear Information System (INIS)

Morlock, G.; Wiesemes, J.; Bachner, D.

1977-01-01

The device described here guarantees the selective removal of hydrogen isotopes from gas phases in order to prevent the occurence of explosive H 2 gas mixtures, or to separate off radioactive tritium in nuclear plants from the gas phase. It consists of a closed container whose walls are selectively penetrable by hydrogen isotopes. It is simultaneously filled compactly and presssure-resistant with a metal bulk (e.g. powder, sponges or the like of titanium or other hydrogen isotope binding metal). Walling and bulk are maintained at suitable working temperatures by means of a system according to the Peltier effect. The whole thing is safeguarded by protective walling. (RB) [de

Gas phase adsorption technology for nitrogen isotope separation and its feasibility for highly enriched nitrogen gas production

International Nuclear Information System (INIS)

Inoue, Masaki; Asaga, Takeo

2000-04-01

Highly enriched nitrogen-15 gas is favorable to reduce radioactive carbon-14 production in reactor. The cost of highly enriched nitrogen-15 gas in mass production is one of the most important subject in nitride fuel option in 'Feasibility Study for FBR and Related Fuel Cycle'. In this work gas phase adsorption technology was verified to be applicable for nitrogen isotope separation and feasible to produce highly enriched nitrogen-15 gas in commercial. Nitrogen isotopes were separated while ammonia gas flows through sodium-A type zeolite column using pressure swing adsorption process. The isotopic ratio of eight samples were measured by high resolution mass spectrometry and Fourier transform microwave spectroscopy. Gas phase adsorption technology was verified to be applicable for nitrogen isotope separation, since the isotopic ratio of nitrogen-15 and nitrogen-14 in samples were more than six times as high as in natural. The cost of highly enriched nitrogen-15 gas in mass production were estimated by the factor method. It revealed that highly enriched nitrogen-15 gas could be supplied in a few hundred yen per gram in mass production. (author)

Separation of uranium isotopes by gas centrifugation

International Nuclear Information System (INIS)

Jordan, I.

1980-05-01

The uranium isotope enrichment is studied by means of the countercurrent gas centrifuge driven by thermal convection. A description is given of (a) the transfer and purification of the uranium hexafluoride used as process gas in the present investigation; (b) the countercurrent centrifuge ZG3; (c) the system designed for the introduction and extraction of the process gas from the centrifuge; (d) the measurement of the process gas flow rate through the centrifuge; (e) the determination of the uranium isotopic abundance by mass spectrometry; (f) the operation and mechanical behavior of the centrifuge and (g) the isotope separation experiments, performed, respectively, at total reflux and with production of enriched material. The results from the separation experiments at total reflux are discussed in terms of the enrichment factor variation with the magnitude and flow profile of the countercurrent given by the temperature difference between the rotor covers. As far as the separation experiments with production are concerned, the discussion of their results is presented through the variation of the enrichment factor as a function of the flow rate, the observed asymmetry of the process and the calculated separative power of the centrifuge. (Author) [pt

Evaluation technology for burnup and generated amount of plutonium by measurement of Xenon isotopic ratio in dissolver off-gas at reprocessing facility (Joint research)

International Nuclear Information System (INIS)

Okano, Masanori; Kuno, Takehiko; Shirouzu, Hidetomo; Yamada, Keiji; Sakai, Toshio; Takahashi, Ichiro; Charlton, William S.; Wells, Cyndi A.; Hemberger, Philip H.

2006-12-01

The amount of Pu in the spent fuel was evaluated from Xe isotopic ratio in off-gas in reprocessing facility, is related to burnup. Six batches of dissolver off-gas (DOG) at spent fuel dissolution process were sampled from the main stack in Tokai Reprocessing Plant (TRP) during BWR fuel (approx. 30GWD/MTU) reprocessing campaign. Xenon isotopic ratio was determined with Gas Chromatography/Mass Spectrometry. Burnup and generated amount of Pu were evaluated with Noble Gas Environmental Monitoring Application code (NOVA), developed by Los Alamos National Laboratory. Inferred burnup evaluated by Xe isotopic measurements and NOVA were in good agreement with those of the declared burnup in the range from -3.8% to 7.1%. Also, the inferred amount of Pu in spent fuel was in good agreed with those of the declared amount of Pu calculated by ORIGEN code in the range from -0.9% to 4.7%. The evaluation technique is applicable for both burnup credit to achieve efficient criticality safety control and a new measurement method for safeguards inspection. (author)

Gas Chromatography-Mass Spectrometric Analysis and Insecticidal ...

African Journals Online (AJOL)

HP

Original Research Article. Gas Chromatography-Mass Spectrometric Analysis and ... into a natural fumigant/insecticide for the control of stored product insects. Keywords: Mallotus ..... stability as well as reduce cost. ACKNOWLEDGEMENT.

Environmental application of elemental speciation analysis based on liquid or gas chromatography hyphenated to inductively coupled plasma mass spectrometry-A review

International Nuclear Information System (INIS)

Popp, Maximilian; Hann, Stephan; Koellensperger, Gunda

2010-01-01

In recent years the number of environmental applications of elemental speciation analysis using inductively coupled plasma mass spectrometry (ICP-MS) as detector has increased significantly. The analytical characteristics, such as extremely low detection limits (LOD) for almost all elements, the wide linear range, the possibility for multi-elemental analysis and the possibility to apply isotope dilution mass spectrometry (IDMS) make ICP-MS an attractive tool for elemental speciation analysis. Two methodological approaches, i.e. the combination of ICP-MS with high performance liquid chromatography (HPLC) and gas chromatography (GC), dominate the field. Besides the investigation of metals and metalloids and their species (e.g. Sn, Hg, As), representing 'classic' elements in environmental science, more recently other elements (e.g. P, S, Br, I) amenable to ICP-MS determination were addressed. In addition, the introduction of isotope dilution analysis and the development of isotopically labeled species-specific standards have contributed to the success of ICP-MS in the field. The aim of this review is to summarize these developments and to highlight recent trends in the environmental application of ICP-MS coupled to GC and HPLC.

Statistical model for classifying the feeding systems of Iberian pigs through Gas Chromatography (GC-FID and Isotope Ratio Mass Spectrometry (GC-C-IRMS

Directory of Open Access Journals (Sweden)

García-Casco, J. M.

2013-04-01

Full Text Available In the present work we have analyzed a total of 734 subcutaneous fat samples from Iberian pigs with different feeding systems for fattening (“Bellota”, “Recebo”, “Campo” and “Cebo” over three consecutive years, 2009-2011. Lipids were extracted from the subcutaneous fat on the rump, and after esterification, they were analyzed by Gas Chromatography (GC-FID and Gas Chromatography- Combustion-Isotope Ratio Mass Spectrometry (GC-C-IRMS. Mean fatty acids and isotope ratios show that there are differences according to the year and feeding systems, two factors that should be taken into account when classifying the animals. The application of different prediction models based on Discriminant analysis has allowed us to establish a method for the classification of animals according to the feeding system type, with a correct percentage of 85% using three or four classification categories (Bellota, Recebo, Campo and/or Cebo and 91% using only two categories, Cebo and Bellota. This model could provide the basis for appropriate classification of Iberian pigs according to their feeding regime.En el presente trabajo se han analizado un total de 734 muestras de tejido subcutáneo de cerdos ibéricos con distintos tipos de alimentación de engorde (Bellota, Recebo, Cebo y Campo a lo largo de tres años consecutivos, 2009-2011. Se han extraído los lípidos de la grasa subcutánea de rabadilla, y después de su esterificación, se han analizado por Cromatografía de gases (GC-FID y por Espectrometría de masas de relaciones isotópicas (GC-C-IRMS. Las medias de los ácidos grasos y de las relaciones isotópicas muestran que existen diferencias según el año y tipo de alimentación, factores que deberían tenerse en cuenta a la hora de clasificar los animales. La aplicación de distintos modelos de predicción basados en análisis discriminante permite establecer un método para la clasificación de los animales según el tipo de alimentación, con

Method and apparatus for isotope separation from a gas stream

International Nuclear Information System (INIS)

Szoke, A.

1978-01-01

A method and apparatus are described for isotope separation and in particular for separating the desired isotope from the gas in which it is contained by irradiating it with a laser. The laser selectively provides kinetic energy to the isotope through inelastic events, monomolecular or bimolecular, in order to cause it to segregate within or fly out of the gas stream in which it is contained

Impact of comprehensive two-dimensional gas chromatography with mass spectrometry on food analysis.

Science.gov (United States)

Tranchida, Peter Q; Purcaro, Giorgia; Maimone, Mariarosa; Mondello, Luigi

2016-01-01

Comprehensive two-dimensional gas chromatography with mass spectrometry has been on the separation-science scene for about 15 years. This three-dimensional method has made a great positive impact on various fields of research, and among these that related to food analysis is certainly at the forefront. The present critical review is based on the use of comprehensive two-dimensional gas chromatography with mass spectrometry in the untargeted (general qualitative profiling and fingerprinting) and targeted analysis of food volatiles; attention is focused not only on its potential in such applications, but also on how recent advances in comprehensive two-dimensional gas chromatography with mass spectrometry will potentially be important for food analysis. Additionally, emphasis is devoted to the many instances in which straightforward gas chromatography with mass spectrometry is a sufficiently-powerful analytical tool. Finally, possible future scenarios in the comprehensive two-dimensional gas chromatography with mass spectrometry food analysis field are discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gas Chromatography-Mass Spectrometric Analysis of Nematicidal ...

African Journals Online (AJOL)

Gas Chromatography-Mass Spectrometric Analysis of Nematicidal Essential Oil of Valeriana ... Tropical Journal of Pharmaceutical Research ... have a potential to be developed to natural nematicides for the control of cereal cyst nematodes.

Gas Chromatography-Mass Spectrometric Analysis and Insecticidal ...

African Journals Online (AJOL)

Tropical Journal of Pharmaceutical Research ... apelta aerial parts was analyzed by gas chromatography/mass spectrometric (GC/MS) to determine its composition. ... into a natural fumigant/insecticide for the control of stored product insects.

Hydrogen isotope exchange in a metal hydride tube

Energy Technology Data Exchange (ETDEWEB)

Robinson, David B. [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

2014-09-01

This report describes a model of the displacement of one hydrogen isotope within a metal hydride tube by a different isotope in the gas phase that is blown through the tube. The model incorporates only the most basic parameters to make a clear connection to the theory of open-tube gas chromatography, and to provide a simple description of how the behavior of the system scales with controllable parameters such as gas velocity and tube radius. A single tube can be seen as a building block for more complex architectures that provide higher molar flow rates or other advanced design goals.

Isotopic mass-dependence of noble gas diffusion coefficients inwater

Energy Technology Data Exchange (ETDEWEB)

Bourg, I.C.; Sposito, G.

2007-06-25

Noble gas isotopes are used extensively as tracers inhydrologic and paleoclimatic studies. These applications requireknowledge of the isotopic mass (m) dependence of noble gas diffusioncoefficients in water (D), which has not been measured but is estimatedusing experimental D-values for the major isotopes along with an untestedrelationship from kinetic theory, D prop m-0.5. We applied moleculardynamics methods to determine the mass dependence of D for four noblegases at 298 K, finding that D prop m-beta with beta<0.2, whichrefutes the kinetic theory model underlying all currentapplications.

Identification of Cyclopentenyl Fatty Acids by Gas Liquid Chromatography and Mass Spectrometry

DEFF Research Database (Denmark)

Shukla, V. K. S.; Abdel-Moety, E. M.; Larsen, Elfinn

1979-01-01

The straight chain fatty acids and the cyclopentenyl fatty acids present in the lipids of Hydnocarpus wightiana seeds were separated as their pyrrolidides by means of gas chromatography. A gas chromatography-mass spectrometry system confirmed the complete separation and permitted the identification...

Quantitative analysis of deuterium by gas chromatography

International Nuclear Information System (INIS)

Isomura, Shohei; Kaetsu, Hayato

1981-01-01

An analytical method for the determination of deuterium concentration in water and hydrogen gas by gas chromatography is described. HD and D 2 in a hydrogen gas sample were separated from H 2 by a column packed with Molecular Sieve 13X, using extra pure hydrogen gas as carrier. A thermal conductivity detector was used. Concentrations of deuterium were determined by comparison with standard samples. The error inherent to the present method was less a 1% on the basis of the calibration curves obtained with the standard samples. The average time required for the analysis was about 3 minutes. (author)

Determination of fission gas yields from isotope ratios

DEFF Research Database (Denmark)

Mogensen, Mogens Bjerg

1983-01-01

This paper describes a method of calculating the actual fission yield of Kr and Xe in nuclear fuel including the effect of neutron capture reactions and decay. The bases for this calculation are the cumulative yields (ref. 1) of Kr and Xe isotopes (or pairs of isotopes) which are unaffected...... by neutron capture reactions, and measured Kr and Xe isotope ratios. Also the burnup contribution from the different fissile heavy isotopes must be known in order to get accurate fission gas yields....

[Uncertainty evaluation of the determination of toxic equivalent quantity of polychlorinated dibenzo-p-dioxins and dibenzofurans in soil by isotope dilution high resolution gas chromatography and high resolution mass spectrometry].

Science.gov (United States)

Du, Bing; Liu Aimin; Huang, Yeru

2014-09-01

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in soil samples were analyzed by isotope dilution method with high resolution gas chromatography and high resolution mass spectrometry (ID-HRGC/HRMS), and the toxic equivalent quantity (TEQ) were calculated. The impacts of major source of measurement uncertainty are discussed, and the combined relative standard uncertainties were calculated for each 2, 3, 7, 8 substituted con- gener. Furthermore, the concentration, combined uncertainty and expanded uncertainty for TEQ of PCDD/Fs in a soil sample in I-TEF, WHO-1998-TEF and WHO-2005-TEF schemes are provided as an example. I-TEF, WHO-1998-TEF and WHO-2005-TEF are the evaluation schemes of toxic equivalent factor (TEF), and are all currently used to describe 2,3,7,8 sub- stituted relative potencies.

Application of gas chromatography to analysis of spirit-based alcoholic beverages.

Science.gov (United States)

Wiśniewska, Paulina; Śliwińska, Magdalena; Dymerski, Tomasz; Wardencki, Waldemar; Namieśnik, Jacek

2015-01-01

Spirit-based beverages are alcoholic drinks; their production processes are dependent on the type and origin of raw materials. The composition of this complex matrix is difficult to analyze, and scientists commonly choose gas chromatography techniques for this reason. With a wide selection of extraction methods and detectors it is possible to provide qualitative and quantitative analysis for many chemical compounds with various functional groups. This article describes different types of gas chromatography techniques and their most commonly used associated extraction techniques (e.g., LLE, SPME, SPE, SFE, and SBME) and detectors (MS, TOFMS, FID, ECD, NPD, AED, O or EPD). Additionally, brief characteristics of internationally popular spirit-based beverages and application of gas chromatography to the analysis of selected alcoholic drinks are presented.

Comparative study of radio gas-chromatography and gas chromatography - mass spectrometry coupling in the identification of metabolites of estrogens and progesterone

International Nuclear Information System (INIS)

Adessi, G.; Nhuan, T.Q.; Jayle, M.F.

1978-01-01

Radio-gas chromatography (RGC) and gas chromatography-mass spectrometry (GC-MS) were used to identify estrogen and progesterone metabolites. The RGC enables the identification of metabolites of labelled precursors ( 3 H)-estradiol-17β and ( 14 C)-progesterone were used as precursors. The GC-MS analytical technique with mass fragmentography, offers the interest of using unlabelled precursors at physiological levels. The identification of metabolites was based on obtaining the mass spectrum or the compiled fragmentogram on the basis of the most characteristic fragment ions. More over, several metabolites can be quantified on the same fragmentogram. Results on the metabolism of estradiol-17β and progesterone by the hepatic tissue of guinea pigs are given. (Auth.)

Simultaneous analysis of urinary phthalate metabolites of residents in Korea using isotope dilution gas chromatography-mass spectrometry.

Science.gov (United States)

Kim, Miok; Song, Na Rae; Choi, Jong-Ho; Lee, Jeongae; Pyo, Heesoo

2014-02-01

Phthalates are used in industry products, household items, and medical tools as plasticizers. Human exposure to phthalates has raised concern about its toxicity. In the present study, optimization was conducted for the simultaneous analysis of eight kinds of phthalate metabolites using gas chromatography-mass spectrometry (GC-MS): MEP, MiBP, MnBP, MBzP, MiNP, MEHP, MEOHP, and MEHHP. In order to minimize the matrix effect and to do quantitative analysis, isotope dilution and LLE-GC-MS methods were performed. Urine samples were enzymatically hydrolyzed, extracted with a mixture of n-hexane and ethyl ether (8:2; v:v), and subsequently derivatized with trimethylsilylation. All eight kinds of analytes showed clear resolution and high reproducibility in GC-MS results. The method detection limit ranged from 0.05 ng/mL to 0.2 ng/mL. Calibration curves were found to be linear from 0.2 to 100 ng/mL with -(2)>0.992. The relative standard deviation of the intraday precision using water and urine ranged from 2.1% to 16.3%. The analysis was performed with urine samples that were collected from adults residing in the Republic of Korea. The analyzed concentration results were compared according to gender and region. As a result, DEHP metabolites showed the highest detected concentration (75.92 μg/g creatinine, 100%), and MiNP, a metabolite of DiNP, showed the lowest detected concentration (0.42 μg/g creatinine, 22.5%). On average, female urine (200.76 μg/g creatinine) had a higher detected concentration of ∑8 phthalate metabolites than male urine. Samples from rural regions (211.96 μg/g creatinine) had higher levels than samples from urban regions. © 2013.

Microbial metabolomics with gas chromatography/mass spectrometry

NARCIS (Netherlands)

Koek, M.M.; Muilwijk, B.; Werf, M.J. van der; Hankemeier, T.

2006-01-01

An analytical method was set up suitable for the analysis of microbial metabolomes, consisting of an oximation and silylation derivatization reaction and subsequent analysis by gas chromatography coupled to mass spectrometry. Microbial matrixes contain many compounds that potentially interfere with

Isotopic enrichment of 15N by ionic exchange chromatography

International Nuclear Information System (INIS)

Trivelin, P.C.O.

1979-01-01

The present paper presents some studies on production of 15 N-enriched ammonium sulphate with 5% atoms by ionic exchange chromatography method. Two systems are described of columns of resin, where experiments were conducted by eluition of NH 4 + bands with sodium hydroxide solution. Analyses were made of the cost of production of 15 N-enriched ammonium sulphate 5% atoms and, based on the experiments developed, a cost was obtained which was compatible with the international price of the product. The isotopic analyses of nitrogen were made by mass spectrometry. (Author) [pt

Separation of boron isotopes by ion exchange chromatography: studies with Duolite-162, a type-II resin

International Nuclear Information System (INIS)

Sharma, B.K.; Subramanian, R.; Balasubramanian, R.; Mathur, P.K.

1994-01-01

The selection of resin plays an important role in the process of separation of boron isotopes by ion exchange chromatography. The determination of (i) ion exchange capacity of Duolite-162 resin for hydroxyl - chloride exchange, (ii) hydroxyl - borate exchange, (iii) isotopic exchange separation factor by batch method and (iv) effect of concentration of boric acid on isotopic exchange separation factor to test the suitability of the above resin for this process are discussed in this report. (author)

Fast temperature programming in gas chromatography using resistive heating

NARCIS (Netherlands)

Dallüge, J.; Ou-Aissa, R.; Vreuls, J.J.; Brinkman, U.A.T.; Veraart, J.R.

1999-01-01

The features of a resistive-heated capillary column for fast temperature-programmed gas chromatography (GC) have been evaluated. Experiments were carried out using a commercial available EZ Flash GC, an assembly which can be used to upgrade existing gas chromatographs. The capillary column is placed

Quantification of 13 priority polycyclic aromatic hydrocarbons in human urine by headspace solid-phase microextraction gas chromatography-isotope dilution mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Campo, Laura [Department of Occupational and Environmental Health, University of Milan and Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Milan (Italy)], E-mail: laura.campo@unimi.it; Mercadante, Rosa; Rossella, Federica; Fustinoni, Silvia [Department of Occupational and Environmental Health, University of Milan and Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Milan (Italy)

2009-01-12

Polycyclic aromatic hydrocarbons (PAHs) are common environmental pollutants in both living and working environments. The aim of this study was the development of a headspace solid-phase microextraction gas chromatography-isotope dilution mass spectrometry (HS-SPME/GC-IDMS) method for the simultaneous quantification of 13 PAHs in urine samples. Different parameters affecting PAHs extraction by HS-SPME were considered and optimized: type/thickness of fiber coatings, extraction temperature/time, desorption temperature/time, ionic strength and sample agitation. The stability of spiked PAHs solutions and of real urine samples stored up to 90 days in containers of different materials was evaluated. In the optimized method, analytes were absorbed for 60 min at 80 deg. C in the sample headspace with a 100 {mu}m polydimethylsiloxane fiber. The method is very specific, with linear range from the limit of quantification to 8.67 x 10{sup 3} ng L{sup -1}, a within-run precision of <20% and a between-run precision of <20% for 2-, 3- and 4-ring compounds and of <30% for 5-ring compounds, trueness within 20% of the spiked concentration, and limit of quantification in the 2.28-2.28 x 10{sup 1} ng L{sup -1} range. An application of the proposed method using 15 urine samples from subjects exposed to PAHs at different environmental levels is shown.

High-precision measurement of phenylalanine δ15N values for environmental samples: a new approach coupling high-pressure liquid chromatography purification and elemental analyzer isotope ratio mass spectrometry.

Science.gov (United States)

Broek, Taylor A B; Walker, Brett D; Andreasen, Dyke H; McCarthy, Matthew D

2013-11-15

Compound-specific isotope analysis of individual amino acids (CSI-AA) is a powerful new tool for tracing nitrogen (N) source and transformation in biogeochemical cycles. Specifically, the δ(15)N value of phenylalanine (δ(15)N(Phe)) represents an increasingly used proxy for source δ(15)N signatures, with particular promise for paleoceanographic applications. However, current derivatization/gas chromatography methods require expensive and relatively uncommon instrumentation, and have relatively low precision, making many potential applications impractical. A new offline approach has been developed for high-precision δ(15)N measurements of amino acids (δ(15)N(AA)), optimized for δ(15)N(Phe) values. Amino acids (AAs) are first purified via high-pressure liquid chromatography (HPLC), using a mixed-phase column and automated fraction collection. The δ(15)N values are determined via offline elemental analyzer-isotope ratio mass spectrometry (EA-IRMS). The combined HPLC/EA-IRMS method separated most protein AAs with sufficient resolution to obtain accurate δ(15)N values, despite significant intra-peak isotopic fractionation. For δ(15)N(Phe) values, the precision was ±0.16‰ for standards, 4× better than gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS; ±0.64‰). We also compared a δ(15)N(Phe) paleo-record from a deep-sea bamboo coral from Monterey Bay, CA, USA, using our method versus GC/C/IRMS. The two methods produced equivalent δ(15)N(Phe) values within error; however, the δ(15)N(Phe) values from HPLC/EA-IRMS had approximately twice the precision of GC/C/IRMS (average stdev of 0.27‰ ± 0.14‰ vs 0.60‰ ± 0.20‰, respectively). These results demonstrate that offline HPLC represents a viable alternative to traditional GC/C/IMRS for δ(15)N(AA) measurement. HPLC/EA-IRMS is more precise and widely available, and therefore useful in applications requiring increased precision for data interpretation (e.g. δ(15)N paleoproxies

DIRECT-DEPOSITION INFRARED SPECTROMETRY WITH GAS AND SUPERCRITICAL FLUID CHROMATOGRAPHY

Science.gov (United States)

A direct-deposition Fourier transform infrared (FT-IR) system has been evaluated for applicability to gas chromatography (GC) and supercritical fluid chromatography (SFC) of environmental analytes. A 100-um i.d. fused-silica transfer line was used for GC, and a 50-um transfer lin...

Radiogas chromatography mass spectrometry in the selected ion monitoring mode

International Nuclear Information System (INIS)

Doerfler, D.L.; Rosenblum, E.R.; Malloy, J.M.; Naworal, J.D.; McManus, I.R.; Campbell, I.M.

1980-01-01

The value of selected ion monitoring in analyzing biological radio isotope incorporation experiments by radiogas chromatography mass spectrometry is illustrated with reference to the biosynthesis of the mycotoxin mycophenolic acid in Penicillium brevicompactum and the mode of action of the anticholesterolemic drug 20,25-diazacholesterol. Both examples used 1-[ 14 C]acetate precursors. It is shown that the increased sensitivity and specificity of the selected ion monitoring mode detector permits straightforward detection and identification of the relatively small cellular pools associated with metabolic intermediates. The computer program RADSIM is described. Problems that still exist in using radiogas gas chromatography mass spectrometry technology to analyse isotope incorporation experiments are discussed. (author)

Multiple-isotope separation in gas centrifuge

International Nuclear Information System (INIS)

Wood, Houston G.; Mason, T.C.; Soubbaramayer

1996-01-01

In previous works, the Onsager's pancake equation was used to provide solution to the internal counter-current flow field, which is necessary to calculate solutions to the isotope transport equation. The diffusion coefficient was assumed to be constant which is a good approximation for gases with large molecular weights, and small differences in the molecular weights of the various isotopes. A new optimization strategy was presented for determining the operating parameters of a gas centrifuge to be used for multiple-component isotope separation. Scoop drag, linear wall temperature gradient, the feed rate ant the cut have been chosen as operating parameters for the optimization. The investigation was restricted to a single centrifuge, and the problem of cascading for multiple-isotope separation was not addressed. The model describing the flow and separation phenomena in centrifuge includes a set of equations describing the fluid dynamics of the counter-current flow and the diffusion equations written for each isotope of the mixture. In this paper, an optimization algorithm is described and applied to an example for the re enrichment of spent reactor uranium

Method to make accurate concentration and isotopic measurements for small gas samples

Science.gov (United States)

Palmer, M. R.; Wahl, E.; Cunningham, K. L.

2013-12-01

Carbon isotopic ratio measurements of CO2 and CH4 provide valuable insight into carbon cycle processes. However, many of these studies, like soil gas, soil flux, and water head space experiments, provide very small gas sample volumes, too small for direct measurement by current constant-flow Cavity Ring-Down (CRDS) isotopic analyzers. Previously, we addressed this issue by developing a sample introduction module which enabled the isotopic ratio measurement of 40ml samples or smaller. However, the system, called the Small Sample Isotope Module (SSIM), does dilute the sample during the delivery with inert carrier gas which causes a ~5% reduction in concentration. The isotopic ratio measurements are not affected by this small dilution, but researchers are naturally interested accurate concentration measurements. We present the accuracy and precision of a new method of using this delivery module which we call 'double injection.' Two portions of the 40ml of the sample (20ml each) are introduced to the analyzer, the first injection of which flushes out the diluting gas and the second injection is measured. The accuracy of this new method is demonstrated by comparing the concentration and isotopic ratio measurements for a gas sampled directly and that same gas measured through the SSIM. The data show that the CO2 concentration measurements were the same within instrument precision. The isotopic ratio precision (1σ) of repeated measurements was 0.16 permil for CO2 and 1.15 permil for CH4 at ambient concentrations. This new method provides a significant enhancement in the information provided by small samples.

Isotope-dilution gas chromatography-mass spectrometry method for the analysis of hydroxyurea.

Science.gov (United States)

Garg, Uttam; Scott, David; Frazee, Clint; Kearns, Gregory; Neville, Kathleen

2015-06-01

Hydroxyurea is used in the treatment of various malignancies and sickle cell disease. There are limited studies on the pharmacokinetics of hydroxyurea, particularly in pediatric patients. An accurate, precise, and sensitive method is needed to support such studies and to monitor therapeutic adherence. We describe a novel gas chromatography-mass spectrometry (GC-MS) method for the determination of hydroxyurea concentration in plasma using stable labeled hydroxyurea C N2 as an internal standard. The method involved an organic extraction followed by the preparation of trimethylsilyl (TMS) derivatives of hydroxyurea for GC-MS selected ion-monitoring analysis. The following mass-to-charge (m/z) ratio ions for silated hydroxyurea and hydroxyurea C N2 were monitored: hydroxyurea-quantitative ion 277, qualifier ions 292 and 249; hydroxyurea C N2-quantitative ion 280, qualifier ion 295. This method was evaluated for reportable range, accuracy, within-run and between-run imprecisions, and limits of quantification. The reportable range for the method was 0.1-100 mcg/mL. All results were accurate within an allowable error of 15%. Within-run and between-run imprecisions were hydroxyurea described here is accurate, sensitive, precise, and robust. Its characteristics make the method suitable for supporting pharmacokinetic studies and/or clinical therapeutic monitoring.

Isotope applications in the environmental field

International Nuclear Information System (INIS)

DeWitt, R.

1978-01-01

Established uses of enriched isotopes in the environmental field were surveyed to determine future trends in isotope needs. Based on established isotope uses, on the projected increase in the pollution problem, and on the apparent social and economic pressure for pollution abatement, a significant demand for enriched isotopes appears to be developing for the assessment and control of air, water, and soil pollutants. Isotopic techniques will be used in combination with conventional methods of detection and measurement, such as gas chromatography, x-ray fluorescence, and atomic absorption. Recent advances in economical isotope separation methods, instrumentation, and methodology promise to place isotopic technology within the reach of most research and industrial institutions. Increased application of isotope techniques appears most likely to occur in areas where data are needed to characterize the movement, behavior, and fate of pollutants in the environment

Contribution to high-temperature chromatography and high-temperature-gas-chromatography-mass spectrometry of lipids

International Nuclear Information System (INIS)

Aichholz, R.

1998-04-01

This thesis describes the use of high temperature gas chromatography for the investigation of unusual triacylglycerols, cyanolipids and bees waxes. The used glass capillary columns were pretreated and coated with tailor made synthesized high temperature stable polysiloxane phases. The selective separation properties of the individual columns were tested with a synthetic lipid mixture. Suitable derivatization procedures for the gaschromatographic analyses of neutral lipids, containing multiple bonds as well as hydroxy-, epoxy-, and carboxyl groups, were developed and optimized. Therefore conjugated olefinic-, conjugated olefinic-acetylenic-, hydroxy-, epoxy-, and conjugated olefinic keto triacylglycerols in miscellaneous plant seed oils as well as hydroxy monoesters, diesters and hydroxy diesters in bees waxes could be analysed directly with high temperature gas chromatography for the first time. In order to elucidate the structures of separated lipid compounds, high temperature gas chromatography was coupled to mass spectrometry and tandem mass spectrometry, respectively. Comparable analytical systems are hitherto not commercial available. Therefore instrumental prerequisites for a comprehensive and detailed analysis of seed oils and bees waxes were established. In GC/MS commonly two ionization methods are used, electron impact ionization and chemical ionization. For the analysis of lipids the first is of limited use only. Due to intensive fragmentation only weak molecular ions are observed. In contrast, the chemical ionization yields in better results. Dominant quasi molecular ions enable an unambiguous determination of the molecular weight. Moreover, characteristic fragment ions provide important indications of certain structural features of the examined compounds. Nevertheless, in some cases the chromatographic resolution was insufficient in order to separate all compounds present in natural lipid mixtures. Owing to the selected detection with mass spectrometry

Chemical stability of levoglucosan: An isotopic perspective

Science.gov (United States)

Sang, X. F.; Gensch, I.; Kammer, B.; Khan, A.; Kleist, E.; Laumer, W.; Schlag, P.; Schmitt, S. H.; Wildt, J.; Zhao, R.; Mungall, E. L.; Abbatt, J. P. D.; Kiendler-Scharr, A.

2016-05-01

The chemical stability of levoglucosan was studied by exploring its isotopic fractionation during the oxidation by hydroxyl radicals. Aqueous solutions as well as mixed (NH4)2SO4-levoglucosan particles were exposed to OH. In both cases, samples experiencing different extents of processing were isotopically analyzed by Thermal Desorption-Gas Chromatography-Isotope Ratio Mass Spectrometry (TD-GC-IRMS). From the dependence of levoglucosan δ13C and concentration on the reaction extent, the kinetic isotope effect (KIE) of the OH oxidation reactions was determined to be 1.00187±0.00027 and 1.00229±0.00018, respectively. Both show good agreement within the uncertainty range. For the heterogeneous oxidation of particulate levoglucosan by gas-phase OH, a reaction rate constant of (2.67±0.03)·10-12 cm3 molecule-1S-1 was derived. The laboratory kinetic data, together with isotopic source and ambient observations, give information on the extent of aerosol chemical processing in the atmosphere.

Gas chromatography of β-diketonates

International Nuclear Information System (INIS)

Burgett, C.A.

1976-01-01

The history of separation of metal complexes by gas chromatography is reviewed. The greatest success has been achieved with metal halides or metal β-diketonates, particularly with chelates of the small elements, Be and Al, and the extremely inert chromium diketonates. Many problems still remain concerning the development of suitable chromatographic techniques for many chelates; however, the technique of synergic solvent extraction, mixed-ligand complex chromatography, the synthesis of new heteroatomic ligands, and the advent of new liquid phases are discussed as means to increase the number of unique techniques for separation and analysis of metals. Methods are suggested and references are cited for chromatographic analysis of elements in the following groups: alkali metals, alkaline earths, Group IIIA, IVB, VB, VIB, VIIB, VIII, IB, and IIB. Special attention is given to separation of the volatile complexes of Sc, Y, the lanthanides, the actinides, and Pb. 156 references

Boron isotope separation by ion exchange chromatography using weakly basic anion exchange resin

International Nuclear Information System (INIS)

Sakuma, Yoichi; Aida, Masao; Okamoto, Makoto; Kakihana, Hidetake

1980-01-01

Isotopic plateau displacement chromatography, a useful method for isotope separation is presented. The boric acid band formed in a column of weakly basic anion exchange resin Diaion WA21 can be eluted with pure water. In order to obtain good accumulation of the isotope effect, a series of experiments with different migration length were carried out. The boron-10 enriched part of the boric acid absorbed band was always preceded by the isotopic plateau part, in which the atomic fraction of boron-10 was maintained at its original value. The atomic fraction of boron-10 at the end of the chromatogram increased with migration length, and in the case of 256-m migration, boron-10 was enriched from its original atomic fraction of 19.84 to 91.00%, the separation factor S being constant irrespective of migration length: S = 1.0100 +- 0.0005. (author)

Gas Chromatography-Mass Spectrometric Analysis of Nematicidal ...

African Journals Online (AJOL)

Purpose: To investigate the chemical composition and nematicidal activity of the essential oil of. Valeriana amurensis ... Methods: The essential oil of V. amurensis roots was obtained by hydrodistillation and analyzed by gas chromatography (GC) ..... Aβ1-40 and Caspase-3 in Alzheimer's disease model rat's brain. J Chin ...

Gas Chromatography Mass Spectrometry of Quassia undulata Seed ...

African Journals Online (AJOL)

Prof. Ogunji

The use of gas chromatography mass spectrometry (GC MS) as a sensitive and specific technique ... cold flow properties and stability of the fuel to oxidation, peroxidation and polymerization .... determinants of both the physical and chemical ...

Online gas chromatography combustion/pyrolysis-isotope ratio mass spectrometry (HRGC-C/P-IRMS) of (+/-)-Dihydroactinidiolide from tea ( Camellia sinensis ) and rooibos tea ( Aspalathus linearis ).

Science.gov (United States)

del Mar Caja, María; Preston, Christina; Menzel, Michael; Kempf, Michael; Schreier, Peter

2009-07-08

Online capillary gas chromatography-isotope ratio mass spectrometry in both the combustion and the pyrolysis modes (HRGC-C/P-IRMS) was employed to perform authentication studies of the flavoring agent (+/-)-dihydroactinidiolide. Thus, the delta(13)C(V-PDB) and delta(2)H(V-SMOW) values of synthetic (ex synthetic beta-ionone and natural beta-carotene) as well as enzymatically (ex synthetic and natural beta-carotene) produced references were studied in comparison with those of the natural substance isolated from black (n = 17) and green teas (n = 6) ( Camellia sinensis ) as well as Rooibos tea ( Aspalathus linearis ) (n = 7). The isotope values determined for both the synthetic and enzymatically produced samples of (+/-)-dihydroactinidiolide reflected the influence of the origin of their educts. Hence, in cases when synthetic educts were used, the delta(13)C(V-PDB) and delta(2)H(V-SMOW) values ranged from -27.0 to -28.4 per thousand and from -28 to -169 per thousand, respectively, whereas the use of natural educts led to ranges from -30.3 to -31.6 per thousand and from -154 to -228 per thousand, respectively. As to the tea samples, delta(13)C(V-PDB) and delta(2)H(V-SMOW) values ranging from -29.0 to -34.1 per thousand and from -153 to -274 per thousand, respectively, were recorded for (+/-)-dihydroactinidiolide from black and green teas, whereas that from Rooibos tea showed (2)H/(1)H ratios ranging from -189 to -210 per thousand as well as slightly enriched values in the (13)C/(12)C ratios ranging from -24.4 to -27.1 per thousand.

Characterization of the fermentation process by gas chromatography Lasiodiplodia theobromae and gas chromatography coupled with mass spectrometry

International Nuclear Information System (INIS)

Castillo Portela, Grolamys; Eng Sanchez, Felipe; Nogueiras Lima, Clara

2014-01-01

Lasiodiplodia theobromae is a fungus, which has been reported by some authors as a high yield producer of the phytohormone jasmonic acid (JA). An indigenous strain of this fungus has been used for producing a fermentation broth with a high JA concentration by the Cuban Research Institute for Sugar Cane Derivatives (ICIDCA), registered as BIOJAS. The broth has been applied to some agricultural crops and demonstrated its economic feasibility as plant growth regulator and biological control of various phytopathogenic microorganisms and pests. Both fermentation broth and biomass from this fungus contain some other metabolites having bioactive properties, for instance, fatty acids. This paper shows the composition and quantification of fatty acids in the biomass using Gas Chromatography (GC) and the identification of substances profile in fermentation broth by Gas Chromatography coupled to Mass Spectrometry (GC-MS). The most fatty acids in the biomass are palmitic, stearic, oleic, linoleic and linolenic acids, being oleic acid the major component. On the other hand, 2,32 % of fatty acid esters; 2,47 % of alkenes; 14,40 % of alcohols; 30,15 % of aldehydes and 21,73 % of paraffins were detected in the composition of fermentation broth

Hyphenated techniques in multidimensional gas chromatography for analysis of wine aroma and related odorants

OpenAIRE

Chin, Sung Tong

2017-01-01

The advent of analytical multidimensional gas chromatography (MDGC) techniques, with recent development in comprehensive two-dimensional gas chromatography (GC×GC) as well as microfluidic technology in conventional heart-cut MDGC, has achieved excellent separation efficiency for advanced characterization of complex volatile and semi-volatile samples, which is unlikely to be accomplished by single dimensional chromatography. This dissertation work has highlighted the potential opportunities fo...

Gas-chromatographic separation of hydrogen isotopes mixtures on capillary molecular sieve 5 A column at 173 K

International Nuclear Information System (INIS)

Bidica, N.; Preda, A.; Stanciu, V.

2002-01-01

Analysis of a gas mixture of hydrogen species, is not too easy because the differences in their physical-chemical properties are very small; the most different are their masses, and consequently most common analytical method appear to be the mass-spectrometry. However, the impossibility to distinguish between two ions (atomic or molecular) with the same mass renders this method as unapplicable. Another problem is the decay of tritium with production of 3 He. These disadvantages of mass-spectrometry have made that other analytical methods, like gas chromatography, to be considered and developed. Thus, there are many papers about various chromatographic columns especially prepared for hydrogen species separation but the preparation and treatment of these columns are very difficult to reproduce. Besides these, there are two other main disadvantages: column operating temperature is very low and long retention times for hydrogen species (more than half an hour) are required. However, the gas-chromatography method still remains an appropriate one. The method described in this paper was based on using a capillary molecular sieve 5A column which has been operated for this kind of separation. The retention times were relatively short, about 8-9 minutes. The carrier gas was Ne and the detector - TCD. In the paper chromatograms for various carrier flow rates and various hydrogen isotope mixtures are presented. The results demonstrated a quite good efficiency for H 2 , HD, D 2 and a not very good one for orthoH 2 -paraH 2 . (authors)

Quantification of 2-acetyl-1-pyrroline in rice by stable isotope dilution assay through headspace solid-phase microextraction coupled to gas chromatography-tandem mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Maraval, Isabelle [UMR Qualisud, CIRAD, 73 Rue J. F. Breton, 34398 Montpellier Cedex 5 (France); UMR Qualisud, Universite Montpellier 2, place E. Bataillon, 34095 Montpellier Cedex 5 (France); Sen, Kemal [Department of Food Engineering, Faculty of Agriculture, University of Cukurova, 01330 Adana (Turkey); Agrebi, Abdelhamid; Menut, Chantal; Morere, Alain [UMR 5247, Institut des Biomolecules Max Mousseron (IBMM), CNRS, Universites Montpellier 2 et 1, Ecole Nationale Superieure de Chimie de Montpellier, 8 Rue de l' Ecole Normale, 34296 Montpellier Cedex 5 (France); Boulanger, Renaud [UMR Qualisud, CIRAD, 73 Rue J. F. Breton, 34398 Montpellier Cedex 5 (France); Gay, Frederic [CIRAD, DORAS Centre, Research and Development Building, Kasetsart University, Bangkok 10900 (Thailand); Mestres, Christian [UMR Qualisud, CIRAD, 73 Rue J. F. Breton, 34398 Montpellier Cedex 5 (France); Gunata, Ziya, E-mail: zgunata@univ-montp2.fr [UMR Qualisud, Universite Montpellier 2, place E. Bataillon, 34095 Montpellier Cedex 5 (France)

2010-08-24

A new and convenient synthesis of 2-acetyl-1-pyrroline (2AP), a potent flavor compound in rice, and its ring-deuterated analog, 2-acetyl-1-d{sub 2}-pyrroline (2AP-d{sub 2}), was reported. A stable isotope dilution assay (SIDA), involving headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-positive chemical ionization-ion trap-tandem mass spectrometry (GC-PCI-IT-MS-MS), was developed for 2AP quantification. A divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber was used for HS-SPME procedure and parameters affecting analytes recovery, such as extraction time and temperature, pH and salt, were studied. The repeatability of the method (n = 10) expressed as relative standard deviation (RSD) was 11.6%. A good linearity was observed from 5.9 to 779 ng of 2AP (r{sup 2} = 0.9989). Limits of detection (LOD) and quantification (LOQ) for 2AP were 0.1 and 0.4 ng g{sup -1} of rice, respectively. The recovery of spiked 2AP from rice matrix was almost complete. The developed method was applied to the quantification of 2AP in aerial parts and grains of scented and non-scented rice cultivars.

Measuring gluconeogenesis using a low dose of 2H2O: advantage of isotope fractionation during gas chromatography.

Science.gov (United States)

Katanik, Jill; McCabe, Brendan J; Brunengraber, Daniel Z; Chandramouli, Visvanathan; Nishiyama, Fumie J; Anderson, Vernon E; Previs, Stephen F

2003-05-01

The contribution of gluconeogenesis to glucose production can be measured by enriching body water with (2)H(2)O to approximately 0.5% (2)H and determining the ratio of (2)H that is bound to carbon-5 vs. carbon-2 of blood glucose. This labeling ratio can be measured using gas chromatography-mass spectrometry after the corresponding glucose carbons are converted to formaldehyde and then to hexamethylenetetramine (HMT). We present a technique for integrating ion chromatograms that allows one to use only 0.05% (2)H in body water (i.e., 10 times less than the current dose). This technique takes advantage of the difference in gas chromatographic retention times of naturally labeled HMT and [(2)H]HMT. We discuss the advantage(s) of using a low dose of (2)H(2)O to quantify the contribution of gluconeogenesis.

Characterization of the designer drug deschloroketamine (2-methylamino-2-phenylcyclohexanone) by gas chromatography/mass spectrometry, liquid chromatography/high-resolution mass spectrometry, multistage mass spectrometry, and nuclear magnetic resonance.

Science.gov (United States)

Frison, Giampietro; Zamengo, Luca; Zancanaro, Flavio; Tisato, Francesco; Traldi, Pietro

2016-01-15

Clinical and forensic toxicology laboratories are challenged every day by the analytical aspects of the new psychoactive substances phenomenon. In this study we describe the analytical characterization of a new ketamine derivative, deschloroketamine (2-methylamino-2-phenylcyclohexanone), contained in seized powders. The analytical techniques employed include gas chromatography/mass spectrometry (GC/MS), liquid chromatography/electrospray ionization coupled with Orbitrap high-resolution/MS (LC/ESI-HRMS), multistage MS (ESI-MS(n)), and NMR. The LC/ESI-HRMS analyses consisted of accurate mass measurements of MH(+) ions in full-scan mode; comparison of experimental and calculated MH(+) isotopic patterns; and examination of the isotopic fine structure (IFS) of the M + 1, M + 2, M + 3 isotopic peaks relative to the monoisotopic M + 0 peak. The collision-induced product ions of the MH(+) ions were studied by both HRMS and MS(n). (1)H and (13)C NMR measurements were carried out to confirm the chemical structure of the analyte. The EI mass spectra obtained by GC/MS analysis showed the presence of molecular ions at m/z 203, and main fragment ions at m/z 175, 174, 160, 147, 146, and 132. The application of LC/ESI-HRMS allowed us to obtain: the accurate mass of deschloroketamine MH(+) ions with a mass accuracy of 1.47 ppm; fully superimposable experimental and calculated MH(+) isotopic patterns, with a relative isotopic abundance value of 3.69 %; and the IFS of the M + 1, M + 2, M + 3 isotopic peaks completely in accordance with theoretical values. Examination of the product ions of MH(+), as well as the study of both (1)H and (13)C NMR spectra, enabled the full characterization of the molecular structure of deschloroketamine. The combination of the employed analytical techniques allowed the characterization of the seized psychoactive substance, in spite of the lack of a reference standard. Deschloroketamine is a ketamine analogue considered to be

Biomarkers, carbon isotopic composition and source rock potentials of Awgu coals, middle Benue trough, Nigeria

Science.gov (United States)

Adedosu, Taofik A.; Sonibare, Oluwadayo O.; Tuo, Jincai; Ekundayo, Olusegun

2012-05-01

Coal and carbonaceous shale samples were collected from two boreholes (BH 94 and BH 120) in Awgu formation of Middle Benue Trough, Nigeria. Source rock potentials of the samples were studied using biomarkers and carbon isotopic composition. Biomarkers in the aliphatic fractions in the samples were studied using Gas Chromatography-Mass Spectrometry (GC-MS). The Carbon isotope analysis of individual n-alkanes in the aliphatic fraction was performed using Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometer (GC-IRMS). The abundance of hopanes, homohopanes (C31-C35), and C29 steranes in the samples indicate terrestrial plant, phytoplankton and cyanobacteria contributions to the organic matter that formed the coal. High (Pr/Ph) ratio (3.04-11.07) and isotopic distribution of individual alkanes showed that the samples consisted of mixed terrestrial/marine organic matter deposited under oxic condition in lacustrine-fluvial/deltaic depositional environment. The maturity parameters derived from biomarker distributions showed that the samples are in the main phase of oil window.

ICP-MS as the method of the determination of gallium, indium and thallium isotope ratios in the studies of isotope effects in the chromatography systems

International Nuclear Information System (INIS)

Herdzik, I.

2006-01-01

The procedure of the determination of gallium, indium and thallium isotope ratios and its application to the studies of the isotope effects in chromatography systems by the ICP-MS method (inductively coupled plasma-mass spectrometry) are presented. It was shown that it is possible to determine the isotope ratios of gallium ( 69/71 Ga), indium ( 113/115 In) and thallium ( 203/205 Tl) with the relative standard deviation 0.03-0.07%. Such precision appeared to be sufficient to calculate the unit separation factors in the column chromatographic processes. (author) [pl

Gas chromatography mass spectrometry : key technology in metabolomics

NARCIS (Netherlands)

Koek, Maud Marijtje

2009-01-01

Metabolomics involves the unbiased quantitative and qualitative analysis of the complete set of metabolites present in cells, body fluids and tissues. Gas chromatography coupled to mass spectrometry (GC-MS) is very suitable for metabolomics analysis, as it combines high separation power with

Extending the molecular application range of gas chromatography

NARCIS (Netherlands)

Kaal, E.; Janssen, H.-G.

2008-01-01

Gas chromatography is an important analytical technique for qualitative and quantitative analysis in a wide range of application areas. It is fast, provides a high peak capacity, is sensitive and allows combination with a wide range of selective detection methods including mass spectrometry.

Fractionation of oxygen and hydrogen isotopes at the hydrate gas forming in the sea sediments

International Nuclear Information System (INIS)

Pashkina, V.I.; Esikov, A.D.

1990-01-01

The paper gives data on isotope composition of interstitial and near-bottom waters sampled in a region of gas-hydrate formation in the Sea of Okhotsk. The studies show that heavy isotopes of oxygen and hydrogen is used in gas-hydrate formation, with the result that isotope composition of its constitution water constitutes δ 18 O=+1.99per mille, δD=+23per mille relatively to SMOW. Formation of autogenic carbonates leads to isotope exchange with interstitial water wich, in turn, changes its primary isotope composition in the direction of increasing of O-18 content. The near-bottom waters are isotope-light relatively to the SMOW standard and to the mean isotope composition of interstitial water in the studied region of gas-hydrate spreading. (orig.) [de

The use of the isotopic composition of individual compounds for correlating spilled oils and refined products in the environment with suspected sources

International Nuclear Information System (INIS)

Philp, R.P.; Allen, J.; Kuder, T.

2002-01-01

Gas chromatography (GC) and gas chromatography/mass spectrometry (CGMS) are two methods generally used to correlate crude oils and refined products found in the environment with their suspected pollution sources. In certain cases, this can be done with bulk carbon isotope compositions, but with crude condensates, or refined products, the lack of biomarkers prohibits the successful use for making unique correlations. Such products can be correlated using an alternative method which makes use of combined gas chromatography-isotope ratio and mass spectrometry (GCIRMS). This method makes it possible to determine the carbon and hydrogen isotopic composition of individual compounds in crude oil, thus producing isotopic fingerprints that could be used in correlation studies. The feasibility of using of GCIRMS to correlate various spilled products in different environments was the main focus of this study. The authors are not proposing that this method will replace GC or GCMS, but are suggesting that it is a powerful tool that could be used in conjunction with the early methods. Carbon and hydrogen isotopic fractionation has been reported for light components such as benzene and toluene. Higher carbon numbered compounds do not seem to undergo major carbon isotopic fractionation as a result of weathering. Hydrogen variations are currently undergoing investigation for compounds with a carbon number greater than C10. Also, isotopic fractionation for refined products has the potential to attenuate naturally. 33 refs., 6 figs

Plasma wave detection in laser spectroscopy and gas chromatography

International Nuclear Information System (INIS)

Franzke, J.; Irmer, A. von; Veza, D.; Niemax, K.

1995-01-01

Frequency changes of plasma oscillations in low-pressure discharges are used for sensitive detection of atomic or molecular trace gases. Analyte selectivity can be either obtained by resonant laser excitation or by gas chromatography

Inductively coupled plasma-mass spectrometry for elemental analysis and isotope ratio determinations in individual organic compounds separated by gas chromatography

International Nuclear Information System (INIS)

Chong, N.S.; Houk, R.S.

1987-01-01

A gas chromatograph (GC) with a packed column was interfaced to an inductively coupled plasma-mass spectrometer (ICP-MS) to yield atomic mass spectra from volatile organic compounds. Atomization of injected compounds was nearly complete and independent of molecular structure, so that elemental ratios could be determined. Detection limits were in the range 0.001 to 400 ng s -1 , depending on the ionization energy of the element and its abundance in the background spectrum. The relative standard deviation of measured isotope ratios varied from 0.4% for Br (i.e., a ratio close to unity) to 18% for N (a very large ratio). Thus, GC-ICP-MS provides elemental and isotope ratio information that is complementary to the molecular information derived from GC-MS with conventional ionization methods

MEMS-Based Micro Gas Chromatography: Design, Fabrication and Characterization

OpenAIRE

Zareian-Jahromi, Mohammad Amin

2009-01-01

This work is focused on the design, fabrication and characterization of high performance MEMS-based micro gas chromatography columns having wide range of applications in the pharmaceutical industry, environmental monitoring, petroleum distillation, clinical chemistry, and food processing. The first part of this work describes different approaches to achieve high-performance microfabricated silicon-glass separation columns for micro gas chromatographic (µGC) systems. The capillary width effec...

On the noble gas isotopic fractionation in naturally occurring gases

International Nuclear Information System (INIS)

Marty, B.

1984-01-01

The isotopic composition of neon in the mantle is an important geochemical constraint on the formation of the earth and subsequent degassing. Some deviation of neon isotopic composition in natural gas and rock samples from the atmospheric value which can not be accounted for by the known nuclear process has been reported, and Nagao et al. interpreted the deviation as the result of mass fractionation in natural gas in Japan. The possible cause of such fractionation was investigated. Gaseous diffusion, such as (a) free-molecule diffusion, (b) mutual diffusion and (c) thermal diffusion, is able to cause isotopic fractionation. After the detailed consideration on these three diffusion processes, conclusion that free-molecule diffusion occurs only in very particular condition, and it is questionable that thermal diffusion occurs in nature, were obtained. (b) which means the interaction of two or more gases, is supposed to occur in nature, and is able to confirm experimentally. In mutual diffusion only, gas transfer is concerned, but other form of fractionation should not be neglected. In solid diffusion, gas is trapped by fine grained sedimentary rocks, and may be fractionated by adsorption and communication to exterior through minute channels. Underground water also works as noble gas reservoir. For example, when gas stream is in contact with water, continuous exchange is possible to take place at the interface of gas and liquid, which contributes to the fractionation. (Ishimitsu, A.)

Experimental study of xenon isotopes production by gas centrifuge

International Nuclear Information System (INIS)

Zhou Mingsheng; Liang Xiongwen; Zhang Yonggang; Dong Jinping

2006-01-01

The gas centrifuge technology is studied for the separation of Xe isotopes. The nature Xe is chosen as processing gas. A four-state cascade is designed to separate 124 Xe to a concentration of being greater than 65% in three separation runs. 124 Xe can be enriched to a concentration 99% in more separation runs using a cascade of more gas centrifuges. (authors)

Assessment of methods for analyzing gaseous mixtures of hydrogen isotopes and helium

International Nuclear Information System (INIS)

Attalla, A.; Bishop, C.T.; Bohl, D.R.; Buxton, T.L.; Sprague, R.E.; Warner, D.K.

1976-01-01

Mass spectrographic methods have served well in the past to analyze gaseous mixtures of the hydrogen isotopes. Alternate methods of analyses are reviewed which offer wider ranges and variety of isotopic determinations. This report describes possible improvements of the mass spectrographic determinations, gas chromatography, anti-Stokes Raman spectroscopy, microwave-induced optical emission spectroscopy, and methods of measuring tritium using radiation detection devices. Precision, accuracy, limitations, and costs are included for some of the methods mentioned. Costs range from $70,000 for the anti-Stokes Raman spectroscopy equipment, which can determine hydrogen isotopes but not helium, to less than $10,000 for the gas chromatographic equipment, which can determine hydrogen isotopes and helium with precision and accuracy comparable to those of the mass spectrometer

Gas chromatography in blood carbon monoxide monitoring

Energy Technology Data Exchange (ETDEWEB)

Drasche, H.; Funk, L.; Herbolsheimer, R.

1975-05-01

A description of a gas chromatography method for monitoring blood carboxyhaemoglobin (HbCO) levels in a very small quantity (100 mcl) of capillary blood: reagents and apparatus, procedures, calculation of results. To calculate HbCO content, an aliquot portion of water-diluted blood is saturated with CO; this saturation obviates the need to determine the haemoglobin or iron blood levels.

Simultaneous Assay of Isotopic Enrichment and Concentration of Guanidinoacetate and Creatine by Gas Chromatography-Mass Spectrometry

Science.gov (United States)

Kasumov, Takhar; Gruca, Lourdes L.; Dasarathy, Srinivasan; Kalhan, Satish C.

2012-01-01

A gas chromatographic-mass spectrometric (GC-MS) method for the simultaneous measurement of isotopic enrichment and concentration of guanidinoacetic acid and creatine in plasma sample for kinetic studies is reported. The method, based on preparation of the bis(trifluoromethyl)-pyrimidine methyl ester derivatives of guanidinoacetic acid and creatine, is robust and sensitive. The lowest measurable m1 and m3 enrichment for guanidinoacetic acid and creatine, respectively, was 0.3%. The calibration curves for measurements of concentration were linear over a range of 0.5-250 μM guanidinoacetic acid and 2-500 μM for creatine. The method was reliable for inter-assay and intra-assay precision, accuracy and linearity. The technique was applied in a healthy adult to determine in vivo fractional synthesis rate of creatine using primed- constant rate infusion of [1-13C]glycine. It was found that isotopic enrichment of guanidinoacetic acid reached plateau by 30 min of infusion of [1-13C]glycine, indicating either a small pool size or a rapid turnover rate or both, of guanidinoacetic acid. In contrast, tracer appearance in creatin 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 rate of synthesis of creatine in-vivo in human and animal studies. PMID:19646413

Investigation of mercury-containing proteins by enriched stable isotopic tracer and size-exclusion chromatography hyphenated to inductively coupled plasma-isotope dilution mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Shi Junwen [Laboratory for Bio-Environmental Health Sciences of Nanoscale Materials and Key Laboratory of Nuclear Analytical Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)]|[Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Feng Weiyue [Laboratory for Bio-Environmental Health Sciences of Nanoscale Materials and Key Laboratory of Nuclear Analytical Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)]. E-mail: fengwy@mail.ihep.ac.cn; Wang Meng [Laboratory for Bio-Environmental Health Sciences of Nanoscale Materials and Key Laboratory of Nuclear Analytical Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)]|[Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Zhang Fang [Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Li Bai [Laboratory for Bio-Environmental Health Sciences of Nanoscale Materials and Key Laboratory of Nuclear Analytical Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Wang Bing; Zhu Motao [Laboratory for Bio-Environmental Health Sciences of Nanoscale Materials and Key Laboratory of Nuclear Analytical Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)]|[Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Chai Zhifang [Laboratory for Bio-Environmental Health Sciences of Nanoscale Materials and Key Laboratory of Nuclear Analytical Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)]|[Institute of Nuclear Technology, Shenzhen University, Shenzhen 518060 (China)]|[Institute of Nanochemistry and Nanosafety, Shanghai University, Shanghai (China)

2007-01-30

In order to investigate trace mercury-containing proteins in maternal rat and their offspring, a method of enriched stable isotopic tracer ({sup 196}Hg and {sup 198}Hg) combined with size-exclusion chromatography (SEC) coupled to inductively coupled plasma-isotope dilution mass spectrometry (ICP-IDMS) was developed. Prior to the analysis, {sup 196}Hg- and {sup 198}Hg-enriched methylmercury was administrated to the pregnant rats. Then the mercury-containing proteins in serum and brain cytosol of the dam and pup rats were separated by size-exclusion columns and the mercury was detected by ICP-MS. The ICP-MS spectrogram of the tracing samples showed significantly elevated {sup 196}Hg and {sup 198}Hg isotopic signals compared with the natural ones, indicating that the detection sensitivity could be increased by the tracer method. The contents of mercury in chromatographic fractions of the dam and pup rat brain cytosol were quantitatively estimated by post-column reverse ID-ICP-MS. The quantitative speciation differences of mercury in brain cytosol between the dam and pup rats were observed, indicating that such studies could be useful for toxicological estimation. Additionally, the isotopic ratio measurement of {sup 198}Hg/{sup 202}Hg in the tracing samples could be used to identify the artifact mercury species caused in the analytical procedure. The study demonstrates that the tracer method combined with high-performance liquid chromatography (HPLC)-ICP-IDMS could provide reliably qualitative and quantitative information on mercury-containing proteins in organisms.

Investigation of mercury-containing proteins by enriched stable isotopic tracer and size-exclusion chromatography hyphenated to inductively coupled plasma-isotope dilution mass spectrometry

International Nuclear Information System (INIS)

Shi Junwen; Feng Weiyue; Wang Meng; Zhang Fang; Li Bai; Wang Bing; Zhu Motao; Chai Zhifang

2007-01-01

In order to investigate trace mercury-containing proteins in maternal rat and their offspring, a method of enriched stable isotopic tracer ( 196 Hg and 198 Hg) combined with size-exclusion chromatography (SEC) coupled to inductively coupled plasma-isotope dilution mass spectrometry (ICP-IDMS) was developed. Prior to the analysis, 196 Hg- and 198 Hg-enriched methylmercury was administrated to the pregnant rats. Then the mercury-containing proteins in serum and brain cytosol of the dam and pup rats were separated by size-exclusion columns and the mercury was detected by ICP-MS. The ICP-MS spectrogram of the tracing samples showed significantly elevated 196 Hg and 198 Hg isotopic signals compared with the natural ones, indicating that the detection sensitivity could be increased by the tracer method. The contents of mercury in chromatographic fractions of the dam and pup rat brain cytosol were quantitatively estimated by post-column reverse ID-ICP-MS. The quantitative speciation differences of mercury in brain cytosol between the dam and pup rats were observed, indicating that such studies could be useful for toxicological estimation. Additionally, the isotopic ratio measurement of 198 Hg/ 202 Hg in the tracing samples could be used to identify the artifact mercury species caused in the analytical procedure. The study demonstrates that the tracer method combined with high-performance liquid chromatography (HPLC)-ICP-IDMS could provide reliably qualitative and quantitative information on mercury-containing proteins in organisms

Gas chromatography-mass spectrometry with supersonic molecular beams.

Science.gov (United States)

Amirav, Aviv; Gordin, Alexander; Poliak, Marina; Fialkov, Alexander B

2008-02-01

Gas chromatography-mass spectrometry (GC-MS) with supersonic molecular beams (SMBs) (also named Supersonic GC-MS) is based on GC and MS interface with SMBs and on the electron ionization (EI) of vibrationally cold analytes in the SMBs (cold EI) in a fly-through ion source. This ion source is inherently inert and further characterized by fast response and vacuum background filtration capability. The same ion source offers three modes of ionization including cold EI, classical EI and cluster chemical ionization (CI). Cold EI, as a main mode, provides enhanced molecular ions combined with an effective library sample identification, which is supplemented and complemented by a powerful isotope abundance analysis method and software. The range of low-volatility and thermally labile compounds amenable for analysis is significantly increased owing to the use of the contact-free, fly-through ion source and the ability to lower sample elution temperatures through the use of high column carrier gas flow rates. Effective, fast GC-MS is enabled particularly owing to the possible use of high column flow rates and improved system selectivity in view of the enhancement of the molecular ion. This fast GC-MS with SMB can be further improved via the added selectivity of MS-MS, which by itself benefits from the enhancement of the molecular ion, the most suitable parent ion for MS-MS. Supersonic GC-MS is characterized by low limits of detection (LOD), and its sensitivity is superior to that of standard GC-MS, particularly for samples that are hard for analysis. The GC separation of the Supersonic GC-MS can be improved with pulsed flow modulation (PFM) GC x GC-MS. Electron ionization LC-MS with SMB can also be combined with the Supersonic GC-MS, with fast and easy switching between these two modes of operation. (c) 2008 John Wiley & Sons, Ltd.

Reconsideration of methane isotope signature as a criterion for the genesis of natural gas: influence of migration on isotopic signatures

International Nuclear Information System (INIS)

Pernaton, E.; Prinzhofer, A.; Schneider, F.

1996-01-01

Experiments were performed in the purpose of studying the isotopic consequences of the diffusional transport of hydrocarbon gases through sediment rocks. Linked to a numerical model, these gas diffusion experiments through as shale porous plug allowed us to correlate porosity and diffusivity of the migration medium. Significant isotopic fractionations (carbon and hydrogen) of methane, and ethane at a lesser degree were observed. This is in contradiction with the actual dogma of isotope geochemistry of natural gases which claims that no fractionation occurs during gas migration. The genetic characterization of natural gases by using the isotopic signature of methane appears as an ambiguous method. (author)

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

International Nuclear Information System (INIS)

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

Phytochemical Profile of Erythrina variegata by Using High-Performance Liquid Chromatography and Gas Chromatography-Mass Spectroscopy Analyses

OpenAIRE

Suriyavathana Muthukrishnan; Subha Palanisamy; Senthilkumar Subramanian; Sumathi Selvaraj; Kavitha Rani Mari; Ramalingam Kuppulingam

2016-01-01

Natural products derived from plant sources have been utilized to treat patients with numerous diseases. The phytochemical constituents present in ethanolic leaf extract of Erythrina variegata (ELEV) were identified by using high-performance liquid chromatography (HPLC) and gas chromatography-mass spectroscopy (GC-MS) analyses. Shade dried leaves were powdered and extracted with ethanol for analyses through HPLC to identify selected flavonoids and through GC-MS to identify other molecules. Th...

Gas chromatography x gas chromatography-time-of-flight mass spectrometry analysis and antibacterial activity of essential oil from Amomum xanthophlebium

International Nuclear Information System (INIS)

Masila, A.; Aminah, I.; Yaakob, W.A.; Nazlina, I.

2011-01-01

Essential oils of fresh leaves, stem, rhizomes and whole aromatic plants of Amomum xanthophlebium (Zingiberaceae) were obtained by hydro distillation. Percentage yields of the leaf, stem and whole plant oils were 0.0032, 0.0074 and 0.0021 % whereas the rhizome oil obtained was very little. Chemical components of each oil and their percentages were determined by Gas Chromatography x Gas Chromatography-Time-of-Flight Mass Spectrometry (GCxGC-TOFMS). Analysis of A. xanthophlebium oils showed that they were dominated by terpenes. Main components in the leaves were allo-aromadendrene (3.41 %), (±)-globulol (2.58 %) and rosifoliol (2.55 %); stem, α-terpineol (4.25 %), rosifoliol (2.41 %) and bingpian (2.27 %); rhizomes, viridiflorol (5.72 %), (±)-globulol (5.23 %) and α-cadinol (4.81 %); whole plants, eucalyptol (4.11 %), l-α-terpineol (2.88 %) and rosifoliol (2.82 %). The stem oil of A. xanthophlebium showed antibacterial activity against Gram-negative Escherichia coli and Gram-positive methicillin-resistant Staphylococcus aureus (MRSA) at the minimum inhibitory concentration of 80 mg/ ml. (author)

Gas Chromatography-Mass Spectroscopic (GC-MS) Analysis of n ...

African Journals Online (AJOL)

1Department of Pharmacognosy and Phytotherapy, 2Department of Pharmaceutics and Pharmaceutical Technology, University of Port Harcourt, Nigeria ... tuber-regium (synonym Pleurotus tuber regium) using gas chromatography-mass spectroscopic (GC- ... Department of Plant Science and Biotechnology,. University of ...

Characteristics of isotope-selective chemical reactor with gas-separating device

International Nuclear Information System (INIS)

Gorshunov, N.M.; Kalitin, S.A.; Laguntsov, N.I.; Neshchimenko, Yu.P.; Sulaberidze, G.A.

1988-01-01

A study was made on characteristics of separating stage, composed of isotope-selective chemical (or photochemical) reactor and membrane separating cascade (MSC), designated for separation of isotope-enriched products from lean reagents. MSC represents the counterflow cascade for separation of two-component mixtures. Calculations show that for the process of carton isotope separation the electric power expences for MSC operation are equal to 20 kWxh/g of CO 2 final product at 13 C isotope content in it equal to 75%. Application of the membrane gas-separating cascade at rather small electric power expenses enables to perform cascading of isotope separation in the course of nonequilibrium chemical reactions

INS gas-filled recoil isotope separator

International Nuclear Information System (INIS)

Miyatake, M.; Nomura, T.; Kawakami, H.

1986-09-01

The characteristics and performance of a small sized gas-filled recoil isotope separator recently made at INS are described. The total efficiency and the ΔBρ/Bρ values have been measured using low velocity 16 O, 40 Ar and 68 As ions and found to be 10 and 5 %, respectively. The Z-dependence of the mean charge is discussed. (author)

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

Science.gov (United States)

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)

Odorant Screening and Quantitation of Thiols in Carmenere Red Wine by Gas Chromatography-Olfactometry and Stable Isotope Dilution Assays.

Science.gov (United States)

Pavez, Carolina; Agosin, Eduardo; Steinhaus, Martin

2016-05-04

The sensory impact of thiols in Vitis vinifera 'Carmenere' red wines was evaluated. For this purpose, aroma extract dilution analysis was applied to the thiols isolated from a Carmenere red wine by affinity chromatography with a mercurated agarose gel. Results revealed the presence of four odorants, identified as 2-furanylmethanethiol, 3-sulfanylhexyl acetate, 3-sulfanyl-1-hexanol, and 2-methyl-3-sulfanyl-1-butanol, with the latter being described here for the first time in Carmenere red wines. Quantitation of the four thiols in the Carmenere wine screened by aroma extract dilution analysis and in three additional Carmenere wines by stable isotope dilution assays resulted in concentrations above the respective orthonasal odor detection threshold values. Triangle tests applied to wine model solutions with and without the addition of the four thiols showed significant differences, thus suggesting that the compounds do have the potential to influence the overall aroma of red wine.

Quantification of four major metabolites of embryotoxic N-methyl- and N-ethyl-2-pyrrolidone in human urine by cooled-injection gas chromatography and isotope dilution mass spectrometry.

Science.gov (United States)

Schindler, Birgit K; Koslitz, Stephan; Meier, Swetlana; Belov, Vladimir N; Koch, Holger M; Weiss, Tobias; Brüning, Thomas; Käfferlein, Heiko U

2012-04-17

N-Methyl- and N-ethyl-2-pyrollidone (NMP and NEP) are frequently used industrial solvents and were shown to be embryotoxic in animal experiments. We developed a sensitive, specific, and robust analytical method based on cooled-injection (CIS) gas chromatography and isotope dilution mass spectrometry to analyze 5-hydroxy-N-ethyl-2-pyrrolidone (5-HNEP) and 2-hydroxy-N-ethylsuccinimide (2-HESI), two newly identified presumed metabolites of NEP, and their corresponding methyl counterparts (5-HNMP, 2-HMSI) in human urine. The urine was spiked with deuterium-labeled analogues of these metabolites. The analytes were separated from urinary matrix by solid-phase extraction and silylated prior to quantification. Validation of this method was carried out by using both, spiked pooled urine samples and urine samples from 56 individuals of the general population with no known occupational exposure to NMP and NEP. Interday and intraday imprecision was better than 8% for all metabolites, while the limits of detection were between 5 and 20 μg/L depending on the analyte. The high sensitivity of the method enables us to quantify NMP and NEP metabolites at current environmental exposures by human biomonitoring.

Determination of vitamins D2 and D3 in selected food matrices by online high-performance liquid chromatography-gas chromatography-mass spectrometry (HPLC-GC-MS).

Science.gov (United States)

Nestola, Marco; Thellmann, Andrea

2015-01-01

An online normal-phase liquid chromatography-gas chromatography-mass spectrometry (HPLC-GC-MS) method was developed for the determination of vitamins D2 and D3 in selected food matrices. Transfer of the sample from HPLC to GC was realized by large volume on-column injection; detection was performed with a time-of-flight mass spectrometer (TOF-MS). Typical GC problems in the determination of vitamin D such as sample degradation or sensitivity issues, previously reported in the literature, were not observed. Determination of total vitamin D content was done by quantitation of its pyro isomer based on an isotopically labelled internal standard (ISTD). Extracted ion traces of analyte and ISTD showed cross-contribution, but non-linearity of the calibration curve was not determined inside the chosen calibration range by selection of appropriate quantifier ions. Absolute limits of detection (LOD) and quantitation (LOQ) for vitamins D2 and D3 were calculated as approximately 50 and 150 pg, respectively. Repeatability with internal standard correction was below 2 %. Good agreement between quantitative results of an established high-performance liquid chromatography with UV detection (HPLC-UV) method and HPLC-GC-MS was found. Sterol-enriched margarine was subjected to HPLC-GC-MS and HPLC-MS/MS for comparison, because HPLC-UV showed strong matrix interferences. HPLC-GC-MS produced comparable results with less manual sample cleanup. In summary, online hyphenation of HPLC and GC allowed a minimization in manual sample preparation with an increase of sample throughput.

Development of a thermal desorption modulator for gas chromatography

NARCIS (Netherlands)

Geus, H.J.; Boer, de J.; Brinkman, U.A.Th.

1997-01-01

The separation space in gas chromatography can be enhanced dramatically by the comprehensive coupling of two independent separation dimensions. An interface between the two columns must accumulate analytes eluting from the first dimension, focus them and at the appropriate moment transfer them to

Gas-phase chemistry of Mo, Ru, W, and Os metal carbonyl complexes

International Nuclear Information System (INIS)

Wang, Y.; Qin, Z.; Fan, F.L.

2014-01-01

Metal carbonyl complexes were used for studying the gas-phase chemical behavior of Mo, Ru, W and Os isotopes with an on-line low temperature isothermal gas chromatography apparatus. Short-lived Mo and Ru isotopes were produced by a 252 Cf spontaneous fission source. Short-lived nuclides of W and Os were produced using the heavy ion reactions 19 F + 159 Tb and 165 Ho, respectively. Short-lived products were thermalized in a recoil chamber filled with a gas mixture of helium and carbon monoxide. The carbonyls formed were then transported through capillaries to an isothermal chromatography column for study of the adsorption behavior as a function of temperature. On-line isothermal chromatography (IC) experiments on Teflon (PTFE) and quartz surfaces showed that short-lived isotopes of the listed elements can form carbonyl complexes which are very volatile and interact most likely in physical sorption processes. Deduced adsorption enthalpies of Mo and Ru carbonyls were -38 ± 2 kJ/mol and -36 ± 2 kJ/mol, respectively. These values are in good agreement with literature data, partly obtained with different chromatographic techniques. A validation of the applied Monte Carlo model to deduce adsorption enthalpies with Mo isotopes of different half-lives proved the validity of the underlying adsorption model. The investigations using a gas-jet system coupled to a heavy ion accelerator without any preseparator clearly showed the limitations of the approach. The He and CO gas mixture, which was directly added into the chamber, will result in decomposition of CO gas and produce some aerosol particles. After the experiment of 173 W and 179 Os in the heavy ion experiments, the Teflon column was covered by a yellowish deposit; the adsorption enthalpy of W and Os carbonyls could therefore not be properly deduced using Monte Carlo simulations. (orig.)

Doping control analysis of anabolic steroids in equine urine by gas chromatography-tandem mass spectrometry.

Science.gov (United States)

Wong, April S Y; Leung, Gary N W; Leung, David K K; Wan, Terence S M

2017-09-01

Anabolic steroids are banned substances in equine sports. Gas chromatography-mass spectrometry (GC-MS) has been the traditional technique for doping control analysis of anabolic steroids in biological samples. Although liquid chromatography-mass spectrometry (LC/MS) has become an important technique in doping control, the detection of saturated hydroxysteroids by LC-MS remains a problem due to their low ionization efficiency under electrospray. The recent development in fast-scanning gas-chromatography-triple-quadrupole mass spectrometry (GC-MS/MS) has provided a better alternative with a significant reduction in chemical noise by means of selective reaction monitoring. Herein, we present a sensitive and selective method for the screening of over 50 anabolic steroids in equine urine using gas chromatography-tandem mass spectrometry (GC-MS/MS). Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Utilization of stable isotopes for characterizing an underground gas generator

International Nuclear Information System (INIS)

Pirard, J.P.; Antenucci, D.; Renard, X.; Letolle, R.

1994-01-01

The principles of isotopic exchange and isotope ratio result interpretation are first reviewed; then, in the framework of an underground coal gasification project in Belgium, experiments and modelling of the underground gas generator have been carried out: isotopic abundances of carbon, hydrogen and oxygen have been measured in the gasifying agent (O 2 , H 2 O) and in the effluent (CO 2 , CO, H 2 , H 2 O, CH 4 , O 2 , heavy oils and various organic and mineral substances). Gasification kinetics and temperatures have been evaluated and isotope application to thermometry is discussed. 1 fig., 9 refs

Gas-centrifuge unit and centrifugal process for isotope separation

International Nuclear Information System (INIS)

Stark, T.M.

1979-01-01

An invention involving a process and apparatus for isotope-separation applications such as uranium-isotope enrichment is disclosed which employs cascades of gas centrifuges. A preferred apparatus relates to an isotope-enrichment unit which includes a first group of cascades of gas centrifuges and an auxiliary cascade. Each cascade has an input, a light-fraction output, and a heavy-fraction output for separating a gaseous-mixture feed including a compound of a light nuclear isotope and a compound of a heavy nuclear isotope into light and heavy fractions respectively enriched and depleted in the light isotope. The cascades of the first group have at least one enriching stage and at least one stripping stage. The unit further includes means for introducing a gaseous-mixture feedstock into each input of the first group of cascades, means for withdrawing at least a portion of a product fraction from the light-fraction outputs of the first group of cascades, and means for withdrawing at least a portion of a waste fraction from the heavy-fraction outputs of the first group of cascades. The isotope-enrichment unit also includes a means for conveying a gaseous-mixture from a light-fraction output of a first cascade included in the first group to the input of the auxiliary cascade so that at least a portion of a light gaseous-mixture fraction produced by the first group of cascades is further separated into a light and a heavy fraction by the auxiliary cascade. At least a portion of a product fraction is withdrawn from the light fraction output of the auxiliary cascade. If the light-fraction output of the first cascade and the heavy-fraction output of the auxiliary cascade are reciprocal outputs, the concentraton of the light isotope in the heavy fraction produced by the auxiliary cascade essentially equals the concentration of the light isotope in the gaseous-mixture feedstock

Pyrolysis-gas chromatography-isotope ratio mass spectrometry for monitoring natural additives in polylactic acid active food packages.

Science.gov (United States)

Llana-Ruíz-Cabello, M; Pichardo, S; Jiménez-Morillo, N T; González-Vila, F J; Guillamón, E; Bermúdez, J M; Aucejo, S; Camean, A M; González-Pérez, J A

2017-11-24

Compound-specific isotope analysis (CSIA) usually requires preparative steps (pretreatments, extraction, derivatization) to get amenable chromatographic analytes from bulk geological, biological or synthetic materials. Analytical pyrolysis (Py-GC/MS) can help to overcome such sample manipulation. This communication describe the results obtained by hyphenating analytical pyrolysis (Py-GC) with carbon isotope-ratio mass spectrometry (IRMS) for the analysis of a polylactic acid (PLA) a based bio-plastic extruded with variable quantities of a natural plant extract or oregano essential oil. The chemical structural information of pyrolysates was first determined by conventional analytical pyrolysis and the measure of δ 13 C in specific compounds was done by coupling a pyrolysis unit to a gas chromatograph connected to a continuous flow IRMS unit (Py-GC-C-IRMS). Using this Py-CSIA device it was possible to trace natural additives with depleted δ 13 C values produced by C3 photosystem vegetation (cymene: -26.7‰±2.52; terpinene: -27.1‰±0.13 and carvacrol: -27.5‰±1.80 from oregano and two unknown structures: -23.3‰±3.32 and -24.4‰±1.70 and butyl valerate: -24.1‰±3.55 from Allium spp.), within the naturally isotopically enriched bio-plastic backbone derived from corn (C4 vegetation) starch (cyclopentanones: -14.2‰±2.11; lactide enantiomers: -9.2‰±1.56 and larger polymeric units: -17.2‰±1.71). This is the first application of Py-CSIA to characterize a bio-plastic and is shown as a promising tool to study such materials, providing not only a fingerprinting, but also valuable information about the origin of the materials, allowing the traceability of additives and minimizing sample preparation. Copyright © 2017 Elsevier B.V. All rights reserved.

Quantification of plasma myo-inositol using gas chromatography-mass spectrometry.

Science.gov (United States)

Guo, Jin; Shi, Yingfei; Xu, Chengbao; Zhong, Rugang; Zhang, Feng; Zhang, Ting; Niu, Bo; Wang, Jianhua

2016-09-01

Myo-inositol (MI) deficiency is associated with an increased risk for neural tube defects (NTDs), mental disorders and metabolic diseases. We developed a gas chromatography-mass spectrometry (GC-MS) method to detect MI in human plasma, which was accurate, relatively efficient and convenient for clinical application. An external standard method was used for determination of plasma MI. Samples were analyzed by GC-MS after derivatization. The stable-isotope labeled internal standard approach was used to validate the method's accuracy. Alpha fetal protein (AFP) was detected by chemiluminescence immunoassay. The method was validated by determining the linearity, sensitivity and recovery rate. There was a good agreement between the internal standard approach and the present method. The NTD-affected pregnancies showed lower plasma MI (P=0.024) and higher AFP levels (P=0.001) than control. Maternal MI level showed a better discrimination in spina bifida subgroup, while AFP level showed a better discrimination in anencephaly subgroup after stratification analysis. We developed a sensitive and reliable method for the detection of clinical plasma MI, which might be a marker for NTDs screening, and established fundamental knowledge for clinical diagnosis and prevention for the diseases related to disturbed MI metabolism. Copyright © 2016 Elsevier B.V. All rights reserved.

Identification of volatiles from pineapple (Ananas comosus L.) pulp by comprehensive two-dimensional gas chromatography and gas chromatography/mass spectrometry.

Science.gov (United States)

Pedroso, Marcio P; Ferreira, Ernesto C; Hantao, Leandro W; Bogusz, Stanislau; Augusto, Fabio

2011-07-01

Combining qualitative data from the chromatographic structure of 2-D gas chromatography with flame ionization detection (GC×GC-FID) and that from gas chromatography-mass spectrometry (GC/MS) should result in a more accurate assignment of the peak identities than the simple analysis by GC/MS, where coelution of analytes is unavoidable in highly complex samples (rendering spectra unsuitable for qualitative purposes) or for compounds in very low concentrations. Using data from GC×GC-FID combined with GC/MS can reveal coelutions that were not detected by mass spectra deconvolution software. In addition, some compounds can be identified according to the structure of the GC×GC-FID chromatogram. In this article, the volatile fractions of fresh and dehydrated pineapple pulp were evaluated. The extraction of the volatiles was performed by dynamic headspace extraction coupled to solid-phase microextraction (DHS-SPME), a technique appropriate for slurries or solid matrices. Extracted analytes were then analyzed by GC×GC-FID and GC/MS. The results obtained using both techniques were combined to improve compound identifications. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chromatographic measurement of hydrogen isotopic and permanent gas impurities in tritium

International Nuclear Information System (INIS)

Warner, D.K.; Kinard, C.; Bohl, D.C.

1976-01-01

This paper describes a gas chromatograph that was designed for dedicated analysis of hydrogen isotopic and permanent gas impurities in tritium and tritium-deuterium mixtures. The instrument that was developed substantially improved the accuracy and precision of hydrogen isotopic analysis in the 20 ppM to one mole percent range as compared with other analytical methods. Several unique design features of the instrument were required due to the radiation and isotopic exchange properties of the tritium in the samples; descriptions of these features are presented along with details of the complete chromatographic system. The experimental procedures used to calibrate the detector and statistically evaluate its performance are given, and the sources of analytical error are cited. The limitations of the present system are also discussed

Application of Pyrolysis - Gas Chromatography/Mass Spectrometry in Failure Analysis in the Automotive Industry

OpenAIRE

Kusch, Peter (Dr.)

2015-01-01

This book chapter describes application examples of gas chromatography/mass spectrometry and pyrolysis – gas chromatography/mass spectrometry in failure analysis for the identification of chemical materials like mineral oils and nitrile rubber gaskets. Furthermore, failure cases demanding identification of polymers/copolymers in fouling on the compressor wall of a car air conditioner and identification of fouling on the surface of a bearing race from the automotive industry are demonstr...

Gas composition and isotopic geochemistry of cuttings, core, and gas hydrate from the JAPEX/JNOC/GSC Mallik 2L-38 gas hydrate research well

Science.gov (United States)

Lorenson, T.D.

1999-01-01

Molecular and isotopic composition of gases from the JAPEX/JNOC/GSC Mallik 2L-38 gas hydrate research well demonstrate that the in situ gases can be divided into three zones composed of mixtures of microbial and thermogenic gases. Sediments penetrated by the well are thermally immature; thus the sediments are probably not a source of thermogenic gas. Thermogenic gas likely migrated from depths below 5000 m. Higher concentrations of gas within and beneath the gas hydrate zone suggest that gas hydrate is a partial barrier to gas migration. Gas hydrate accumulations occur wholly within zone 3, below the base of permafrost. The gas in gas hydrate resembles, in part, the thermogenic gas in surrounding sediments and gas desorbed from lignite. Gas hydrate composition implies that the primary gas hydrate form is Structure I. However, Structure II stabilizing gases are more concentrated and isotopically partitioned in gas hydrate relative to the sediment hosting the gas hydrate, implying that Structure II gas hydrate may be present in small quantities.

Tritium removal by hydrogen isotopic exchange between hydrogen gas and water on hydrophobic catalyst

International Nuclear Information System (INIS)

Morishita, T.; Isomura, S.; Izawa, H.; Nakane, R.

1980-01-01

Many kinds of the hydrophobic catalysts for hydrogen isotopic exchange between hydrogen gas and water have been prepared. The carriers are the hydrophobic organic materials such as polytetrafluoroethylene(PTFE), monofluorocarbon-PTFE mixture(PTFE-FC), and styrene-divinylbenzene copolymer(SDB). 0.1 to 2 wt % Pt is deposited on the carriers. The Pt/SDB catalyst has much higher activity than the Pt/PTFE catalyst and the Pt/PTFE-FC catalyst shows the intermediate value of catalytic activity. The observation of electron microscope shows that the degrees of dispersion of Pt particles on the hydrophobic carriers result in the difference of catalytic activities. A gas-liquid separated type column containing ten stages is constructed. Each stage is composed of both the hydrophobic catalyst bed for the hydrogen gas/water vapor isotopic exchange and the packed column type bed for the water vapor/liquid water isotopic exchange. In the column hydrogen gas and water flow countercurrently and hydrogen isotopes are separated

GasBench/isotope ratio mass spectrometry: a carbon isotope approach to detect exogenous CO(2) in sparkling drinks.

Science.gov (United States)

Cabañero, Ana I; San-Hipólito, Tamar; Rupérez, Mercedes

2007-01-01

A new procedure for the determination of carbon dioxide (CO(2)) (13)C/(12)C isotope ratios, using direct injection into a GasBench/isotope ratio mass spectrometry (GasBench/IRMS) system, has been developed to improve isotopic methods devoted to the study of the authenticity of sparkling drinks. Thirty-nine commercial sparkling drink samples from various origins were analyzed. Values of delta(13)C(cava) ranged from -20.30 per thousand to -23.63 per thousand, when C3 sugar addition was performed for a second alcoholic fermentation. Values of delta(13)C(water) ranged from -5.59 per thousand to -6.87 per thousand in the case of naturally carbonated water or water fortified with gas from the spring, and delta(13)C(water) ranged from -29.36 per thousand to -42.09 per thousand when industrial CO(2) was added. It has been demonstrated that the addition of C4 sugar to semi-sparkling wine (aguja) and industrial CO(2) addition to sparkling wine (cava) or water can be detected. The new procedure has advantages over existing methods in terms of analysis time and sample treatment. In addition, it is the first isotopic method developed that allows (13)C/(12)C determination directly from a liquid sample without previous CO(2) extraction. No significant isotopic fractionation was observed nor any influence by secondary compounds present in the liquid phase. Copyright (c) 2007 John Wiley & Sons, Ltd.

Recent advances in liquid and gas chromatography methodology for extending coverage of the metabolome.

Science.gov (United States)

Haggarty, Jennifer; Burgess, Karl Ev

2017-02-01

The metabolome is the complete complement of metabolites (small organic biomolecules). In order to comprehensively understand the effect of stimuli on a biological system, it is important to detect as many of the metabolites within that system as possible. This review briefly describes some new advances in liquid and gas chromatography to improve coverage of the metabolome, including the serial combination of two columns in tandem, column switching and different variations of two-dimensional chromatography. Supercritical fluid chromatography could provide complimentary data to liquid and gas chromatography. Although there have been many recent advancements in the field of metabolomics, it is evident that a combination, rather than a single method, is required to approach full coverage of the metabolome. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Recent progress of chiral stationary phases for separation of enantiomers in gas chromatography.

Science.gov (United States)

Xie, Sheng-Ming; Yuan, Li-Ming

2017-01-01

Chromatography techniques based on chiral stationary phases are widely used for the separation of enantiomers. In particular, gas chromatography has developed rapidly in recent years due to its merits such as fast analysis speed, lower consumption of stationary phases and analytes, higher column efficiency, making it a better choice for chiral separation in diverse industries. This article summarizes recent progress of novel chiral stationary phases based on cyclofructan derivatives and chiral porous materials including chiral metal-organic frameworks, chiral porous organic frameworks, chiral inorganic mesoporous materials, and chiral porous organic cages in gas chromatography, covering original research papers published since 2010. The chiral recognition properties and mechanisms of separation toward enantiomers are also introduced. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gas chromatography-mass spectrometry and high-performance liquid chromatographic analyses of thermal degradation products of common plastics

NARCIS (Netherlands)

Pacakova, V.; Leclercq, P.A.

1991-01-01

The thermo-oxidation of five commonly used materials, namely low-density polyethylene, retarded polyethylene, paper with a polyethylene foil, a milk package and filled polypropylene, was studied. Capillary gas chromatography and gas chromatography-mass spectrometry were used to analyze the volatile

Mathematical Modeling of Nonstationary Separation Processes in Gas Centrifuge Cascade for Separation of Multicomponent Isotope Mixtures

Directory of Open Access Journals (Sweden)

Orlov Alexey

2016-01-01

Full Text Available This article presents results of development of the mathematical model of nonstationary separation processes occurring in gas centrifuge cascades for separation of multicomponent isotope mixtures. This model was used for the calculation parameters of gas centrifuge cascade for separation of germanium isotopes. Comparison of obtained values with results of other authors revealed that developed mathematical model is adequate to describe nonstationary separation processes in gas centrifuge cascades for separation of multicomponent isotope mixtures.

Hydrogen sulfide measurement by headspace-gas chromatography-mass spectrometry (HS-GC-MS): application to gaseous samples and gas dissolved in muscle.

Science.gov (United States)

Varlet, Vincent; Giuliani, Nicole; Palmiere, Cristian; Maujean, Géraldine; Augsburger, Marc

2015-01-01

The aim of our study was to present a new headspace-gas chromatography-mass spectrometry (HS-GC-MS) method applicable to the routine determination of hydrogen sulfide (H(2)S) concentrations in biological and gaseous samples. The primary analytical drawback of the GC/MS methods for H(2)S measurement discussed in the literature was the absence of a specific H(2)S internal standard required to perform quantification. Although a deuterated hydrogen sulfide (D(2)S) standard is currently available, this standard is not often used because this standard is expensive and is only available in the gas phase. As an alternative approach, D(2)S can be generated in situ by reacting deuterated chloride with sodium sulfide; however, this technique can lead to low recovery yield and potential isotopic fractionation. Therefore, N(2)O was chosen for use as an internal standard. This method allows precise measurements of H(2)S concentrations in biological and gaseous samples. Therefore, a full validation using accuracy profile based on the β-expectation tolerance interval is presented. Finally, this method was applied to quantify H(2)S in an actual case of H(2)S fatal intoxication. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The Use of Gas Chromatography for Biogas Analysis

Science.gov (United States)

Andersen, Amanda; Seeley, John; Aurandt, Jennifer

2010-04-01

Energy from natural gas accounts for 24 percent of energy consumed in the US. Natural gas is a robust form of energy which is rich in methane content and is low in impurities. This quality suggests that it is a very clean and safe gas; it can be used in providing heat, a source for cooking, and in powering vehicles. The downside is that it is a non-renewable resource. On the contrary, methane rich gas that is produced by the breakdown of organic material in an anaerobic environment, called biogas, is a renewable energy source. This research focuses on the gas analysis portion of the creation of the anaerobic digestion and verification laboratory where content and forensic analysis of biogas is performed. Gas Chromatography is implemented as the optimal analytical tool for quantifying the components of the biogas including methane, carbon dioxide, hydrogen sulfide and siloxanes. In addition, the problems associated with the undesirable components are discussed. Anaerobic digestion of primary sludge has consistently produced about 55 percent methane; future goals of this research include studying different substrates to increase the methane yield and decrease levels of impurities in the gas.

Gas chromatography-mass spectrometry and high-performance liquid chromatographic analyses of thermal degradation products of common plastics

OpenAIRE

Pacakova, V.; Leclercq, P.A.

1991-01-01

The thermo-oxidation of five commonly used materials, namely low-density polyethylene, retarded polyethylene, paper with a polyethylene foil, a milk package and filled polypropylene, was studied. Capillary gas chromatography and gas chromatography-mass spectrometry were used to analyze the volatile degradation products, while high-performance liquid chromatography was employed to measure polycyclic aromatic hydrocarbons. The results are discussed from the point of view of toxicity of the prod...

Fatty Acid and Carbon Isotopic Evidence for type I Methanotrophs in Microbial Mats from a Shallow Marine Gas Seep, Coal Oil Point, CA.

Science.gov (United States)

Ding, H.; Valentine, D.

2005-12-01

To study the microbial community in a Southern California seep field, sediment and bacterial mat samples were collected from natural gas-bearing and gas-free surfaces at two distinct seeps in the Coal Oil Point seep field, offshore Santa Barbara. Fatty acids in these samples were extracted, analyzed and identified. Using gas chromatography (GC), more than 30 different fatty acids were separated. Generally, fatty acid concentrations in natural gas-bearing samples were about 5-fold higher compared to gas-free samples. Using gas chromatography mass sepctrometry (GC-MS), all separated fatty acids were identified in each sample. The major constituents included saturated 14:0, 16:0, 18:0, branched i-15, a-15 and unsaturated 16:1 and 18:1 series fatty acids. GC-IRMS (isotope ratio mass spectrometry) analysis provided the 13C of all major fatty acids and some 16:1 series fatty acids were found to be more depleted than -40% in samples associated with gas seepage. After treatment with dimethyl disufide (DMDS), the 16:1 series fatty acids were resolved into five distinct components, including common composition 16:1(7), bacterial specific i-16:1(7) and typical biomarkers of type I methnotrophs 16:1(8), 16(6) and 16:1(5), suggesting an important role for methnotrophs in seep sediments and microbial mats. These results provide evidence for the activity of type I methanotrophic bacteria in microbial mats and surficial sediments at the Coal Oil Point seep field, and have implications for methane cycling in this and other seep

A double isotope dilution method for assaying of polycyclic aromatic hydrocarbons in cigarette smoke condensate

International Nuclear Information System (INIS)

Bechtold, W.E.; Chen, B.T.

1988-01-01

This report describes a double isotope dilution method for analysis of the polycyclic aromatic hydrocarbons (PAH) phenanthrene, fluor-anthene, pyrene, and benzo[a]pyrene in cigarette smoke particulates. The first isotope dilution used deuterated analogues of the first three PAH as internal standards. The second isotope dilution, for benzo[a]pyrene, used the tritiated analogue as an internal standard. The PAH were isolated from extracts of cigarette smoke particulates using a two-step procedure based on selective extraction from aqueous dimethyl sulfoxide (DMSO) followed by chromatography on silica gel extraction columns. After isolation, aliquots of the samples were analyzed for phenanthrene, pyrene, and fluoranthene by gas chromatography with mass spectrometric detection (GC/MS). Separate aliquots of the samples were analyzed for benzo[a]pyrene by high pressure liquid chromatography with fluorescence detection followed by liquid scintillation spectrometry. PAH levels from cigarette smoke condensates collected from different exposure modes were compared; no exposure-related differences were found. (author)

Automatic isotope gas analysis of tritium labelled organic materials Pt. 1

International Nuclear Information System (INIS)

Gacs, I.; Mlinko, S.

1978-01-01

A new automatic procedure developed to convert tritium in HTO hydrogen for subsequent on-line gas counting is described. The water containing tritium is introduced into a column prepared from molecular sieve-5A and heated to 550 deg C. The tritium is transferred by isotopic exchange into hydrogen flowing through the column. The radioactive gas is led into an internal detector for radioactivity measurement. The procedure is free of memory effects, provides quantitative recovery with analytical reproducibility better than 0.5% rel. at a preset number of counts. The experimental and analytical results indicate that isotopic exchange between HTO and hydrogen over a column prepared from alumina or molecular sieve-5A can be successfully applied for the quantitative transfer of tritium from HTO into hydrogen for on-line gas countinq. This provides an analytical procedure for the automatic determination of tritium in water with an analytical reproducibility better than 0.5% rel. The exchange process will also be suitable for rapid tritium transfer from water formed during the decomposition of tritium-labelled organic compounds or biological materials. The application of the procedure in automatic isotope gas analysis of organic materials labelled with tritium will be described in subsequent papers (Parts II and III). (T.G.)

Carbon Isotopic Ratios of Amino Acids in Stardust-Returned Samples

Science.gov (United States)

Elsila, Jamie E.; Glavin, Daniel P.; Dworkin, Jason P.

2009-01-01

NASA's Stardust spacecraft returned to Earth samples from comet 81P/Wild 2 in January 2006. Preliminary examinations revealed the presence of a suite of organic compounds including several amines and amino acids, but the origin of these compounds could not be identified. Here. we present the carbon isotopic ratios of glycine and E-aminocaproic acid (EACH), the two most abundant amino acids observed, in Stardust-returned foil samples measured by gas chromatography-combustion-isotope ratio crass spectrometry coupled with quadrupole mass spectrometry (GC-QMS/IRMS).

Determination of the trace TBP in industrial feed liquid by gas chromatography

International Nuclear Information System (INIS)

Gao Yuehua; Jiang Junqing; Mu Ling; Yang Songtao

2012-01-01

The determination of the trace TBP in kerosene of the industrial feed liquid by gas chromatography is studied in the paper. It first takes the purification treatment for the kerosene containing trace TBP. The plutonium is removed by 0.2 mol/L ferrous sulfamate-1 mol/L nitric acid using the back-extraction. The uranium and the nitric acid in the organic phase are removed by the deionized water. The impurity which affect the measurement of the TBP and is harmful to the gas chromatograph are eliminated. Then the content of the TBP of the organic phase can be determined by gas chromatography. Results show that the measuring range of the content of the TBP is 0.02% ∼ 2%. The precision of the method is better than 5% and the recovery is between 95%∼106%. (authors)

On-line gas chromatography combustion/pyrolysis isotope ratio mass spectrometry (HRGC-C/P-IRMS) of pineapple (Ananas comosus L. Merr.) volatiles.

Science.gov (United States)

Preston, Christina; Richling, Elke; Elss, Sandra; Appel, Markus; Heckel, Frank; Hartlieb, Ariane; Schreier, Peter

2003-12-31

By use of extracts prepared by liquid-liquid separation of the volatiles from self-prepared juices of pineapple fruits (Ananas comosus) (n = 14) as well as commercial pineapple recovery aromas/water phases (n = 3), on-line capillary gas chromatography-isotope ratio mass spectrometry was employed in the combustion (C) and the pyrolysis (P) modes (HRGC-C/P-IRMS) to determine the delta(13)C(VPDB) and delta(2)H(VSMOW) values of selected pineapple flavor constituents. In addition to methyl 2-methylbutanoate 1, ethyl 2-methylbutanoate 2, methyl hexanoate 3, ethyl hexanoate 4, and 2,5-dimethyl-4-methoxy-3[2H]-furanone 5, each originating from the fruit, the delta(13)C(VPDB) and delta(2)H(VSMOW) data of commercial synthetic 1-5 and "natural" (biotechnologically derived) 1-4 were determined. With delta(13)C(VPDB) data of pineapple volatiles 1-4 varying from -12.8 to -24.4 per thousand, the range expected for CAM metabolism was observed. Compound 5 showed higher depletion from -20.9 to -28.6 per thousand. A similar situation was given for the delta(2)H(VSMOW) values of 3-5 from pineapple ranging from -118 to -191 per thousand, whereas 1 and 2 showed higher depleted values from -184 to -263 per thousand. In nearly all cases, analytical differentiation of 1-5 from pineapple and natural as well as synthetic origin was possible. In general, natural and synthetic 1-5 exhibited delta(13)C(VPDB) data ranging from -11.8 to -32.2 per thousand and -22.7 to -35.9 per thousand, respectively. Their delta(2)H(VSMOW) data were in the range from -242 to -323 per thousand and -49 to -163 per thousand, respectively.

Simultaneous detection of xenon and krypton in equine plasma by gas chromatography-tandem mass spectrometry for doping control.

Science.gov (United States)

Kwok, Wai Him; Choi, Timmy L S; So, Pui-Kin; Yao, Zhong-Ping; Wan, Terence S M

2017-02-01

Xenon can activate the hypoxia-inducible factors (HIFs). As such, it has been allegedly used in human sports for increasing erythropoiesis. Krypton, another noble gas with reported narcosis effect, can also be expected to be a potential and less expensive erythropoiesis stimulating agent. This has raised concern about the misuse of noble gases as doping agents in equine sports. The aim of the present study is to establish a method for the simultaneous detection of xenon and krypton in equine plasma for the purpose of doping control. Xenon- or krypton-fortified equine plasma samples were prepared according to reported protocols. The target noble gases were simultaneously detected by gas chromatography-triple quadrupole mass spectrometry using headspace injection. Three xenon isotopes at m/z 129, 131, and 132, and four krypton isotopes at m/z 82, 83, 84, and 86 were targeted in selected reaction monitoring mode (with the precursor ions and product ions at identical mass settings), allowing unambiguous identification of the target analytes. Limits of detection for xenon and krypton were about 19 pmol/mL and 98 pmol/mL, respectively. Precision for both analytes was less than 15%. The method has good specificity as background analyte signals were not observed in negative equine plasma samples (n = 73). Loss of analytes under different storage temperatures has also been evaluated. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Using GC-combustion isotope ratio mass spectrometry for confirming steroid administration from urinary metabolites in humans and animals

International Nuclear Information System (INIS)

Phillips, A.; Churchman, D.; Davis, S.

2000-01-01

Gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) was used to study the incorporation of exogenous testosterone enanthate into excreted urinary 5α- and 5β-androstane-3α, 17β-diols

Online stable carbon isotope ratio measurement in formic acid, acetic acid, methanol and ethanol in water by high performance liquid chromatography-isotope ratio mass spectrometry

International Nuclear Information System (INIS)

Tagami, Keiko; Uchida, Shigeo

2008-01-01

A suitable analysis condition was determined for high performance liquid chromatography-isotope ratio mass spectrometry (HPLC-IRMS) while making sequential measurements of stable carbon isotope ratios of δ 13 C in formic acid, acetic acid, methanol and ethanol dissolved in water. For this online column separation method, organic reagents are not applicable due to carbon contamination; thus, water and KH 2 PO 4 at low concentrations were tested as mobile phase in combination with a HyPURITY AQUASTAR TM column. Formic acid, acetic acid, methanol and ethanol were separated when 2 mM KH 2 PO 4 aqueous solution was used. Under the determined analysis condition for HPLC-IRMS, carbon concentrations could be measured quantitatively as well as carbon isotope ratio when carbon concentration was higher than 0.4 mM L for each chemical

Development of conjugate methods with gas chromatography for inorganic compounds analysis

International Nuclear Information System (INIS)

Baccan, N.

1975-01-01

The application of gas chromatography combined with mass spectrometry or with nuclear methods for the analysis of inorganic compounds is studied. The advantages of the use of a gas chromatograph coupled with a quadrupole mass spectrometer or with a high resolution radiation detector, are discussed. We also studied the formation and solvent extraction of metal chelates; an aliquot of the organic phase was directly injected into the gas chromatograph and the eluted compounds were detected by mass spectrometry or, when radioactive, by nuclear methods. (author)

[Compound preservative and cyclamat determinated by gas chromatography].

Science.gov (United States)

Xin, Ruozhu; Ding, Mei; Zheng, Xianguang; Li, Yajuan

2008-07-01

To establish a gas chromatography method for synchronous determination of six preservatives and cyclamat in cake and pastry. The pre-treatment of complicated compound was finished by dialysis cleaning technology. The interference of the complicated foundation body in the cake and pastry was removed by the best dialysis condition: 2 g/L NaOH of dialysis fluid was dialyzed at the temperature of 25 degrees C for 24h, and the six preservatives and cyclamat (sorbic acid, benzoic acid, dehydroacetic acid, ethylparabenum, propylparabenum, butylparabenun and sodium cyclamate) were synchronously seperated by 60-80 mesh Chromosorb WAW DMCS glass packing column of intercoated 5% DEGS + 1% H3 PO4. The seven components in the sample had a good lining relation at the concentration 100 -5000 mg/L when the external standard method was used, and their correlation coefficients were 0.9993-0.9998, and their average recovery rates were 87.5%-101.9%, and their relative standard deviations were 0.64%-3.3%, and detection limits were 1.1-8.8 mg/L. This method could be used to quickly analyse the compound preservatives of the large batch cake and pastry through the common gas chromatography and packed column and this method was simple, accurate and quick.

Tunable secondary dimension selectivity in comprehensive two-dimensional gas chromatography

NARCIS (Netherlands)

Mommers, J.; Pluimakers, G.; Knooren, J.; Dutriez, T.; van der Wal, S.

2013-01-01

In this paper two tunable two-dimensional gas chromatography setups are compared and described in which the secondary dimension consists of two different capillary columns coupled in series. In the first setup the selectivity of the second dimension can be tuned by adjusting the effective column

Isotope separation

International Nuclear Information System (INIS)

Bartlett, R.J.; Morrey, J.R.

1978-01-01

A method and apparatus is described for separating gas molecules containing one isotope of an element from gas molecules containing other isotopes of the same element in which all of the molecules of the gas are at the same electronic state in their ground state. Gas molecules in a gas stream containing one of the isotopes are selectively excited to a different electronic state while leaving the other gas molecules in their original ground state. Gas molecules containing one of the isotopes are then deflected from the other gas molecules in the stream and thus physically separated

Isotope ratio monitoring LC/MS (IRM-LC/MS): new applications

International Nuclear Information System (INIS)

Juchelka, D; Hilkert, A.; Krummen, M.

2005-01-01

With the introduction of compound specific isotope analysis by isotope ratio monitoring GC/ MS (IRM-GC/MS) the immediate demand for similar applications using HPLC was created. Many compounds of biological, medical, pharmaceutical and environmental interest are not volatile or too polar. Consequently, they cannot be directly analyzed by gas chromatography. In IRM-GC/MS the carrier is helium, which does not interfere with the essential combust ion step prior to isotope ratio mass spectrometry (IRMS). In opposite the LC mobile phase has inhibited a similar direct conversion up to now. All earlier IRM-LC/MS approaches were based on the removal of the liquid phase prior to combustion risking fractionation of the isotope ratios of the eluted compounds. To avoid such restrictions we developed a new continuous flow concept for the coupling of an HPLC system to the isotope ratio MS for 13 C/ 12C isotope ratio analysis. In the Finnigan LC IsoLink, the liquid phase is not removed from the sample prior to oxidation. The sample is oxidized still in the mobile phase followed by on-line separation of the CO 2 from the liquid phase and transfer into the isotope ratio MS. Therefore, this strategy is based on water and inorganic buffers as mobile phase. The new approach opens up a whole new world in the application of gas isotope ratio mass spectrometry. The 13 C/ 12 C ratio s of organic acids, amino acids, carbohydrates and nucleotides can now be measured. These components typically within a complex matrix are separated by liquid chromatography followed by on-line determination of the isotope ratios. The draw backs of using derivatization and off-line preparation procedures can now be over come. This new technique allow s studying biochemical cycles, running tracer experiments and determining the origin of components. Applications from different scientific areas such as biogeochemistry, molecular biology, and pharmacy as well as authenticity control o f foods will be presented

Method for determination of stable carbon isotope ratio of methylnitrophenols in atmospheric particulate matter

Directory of Open Access Journals (Sweden)

S. Moukhtar

2011-11-01

Full Text Available A technique for the measurement of the stable isotope ratio of methylnitrophenols in atmospheric particulate matter is presented. Atmospheric samples from rural and suburban areas were collected for evaluation of the procedure. Particulate matter was collected on quartz fibre filters using dichotomous high volume air samplers. Methylnitrophenols were extracted from the filters using acetonitrile. The sample was then purified using a combination of high-performance liquid chromatography and solid phase extraction. The final solution was then divided into two aliquots. To one aliquot, a derivatising agent, Bis(trimethylsilyltrifluoroacetamide, was added for Gas Chromatography-Mass Spectrometry analysis. The second half of the sample was stored in a refrigerator. For samples with concentrations exceeding 1 ng μl⁻¹, the second half of the sample was used for measurement of stable carbon isotope ratios by Gas Chromatography-Isotope Ratio Mass Spectrometry.

The procedure described in this paper provides a method for the analysis of methylnitrophenols in atmospheric particulate matter at concentrations as low as 0.3 pg m⁻³ and for stable isotope ratios with an accuracy of better than ±0.5‰ for concentrations exceeding 100 pg m⁻³.

In all atmospheric particulate matter samples analysed, 2-methyl-4-nitrophenol was found to be the most abundant methylnitrophenol, with concentrations ranging from the low pg m⁻³ range in rural areas to more than 200 pg m⁻³ in some samples from a suburban location.

Mathematical modeling of filling of gas centrifuge cascade for nickel isotope separation by various feed flow rate

Science.gov (United States)

Ushakov, Anton; Orlov, Alexey; Sovach, Victor P.

2018-03-01

This article presents the results of research filling of gas centrifuge cascade for separation of the multicomponent isotope mixture with process gas by various feed flow rate. It has been used mathematical model of the nonstationary hydraulic and separation processes occurring in the gas centrifuge cascade. The research object is definition of the regularity transient of nickel isotopes into cascade during filling of the cascade. It is shown that isotope concentrations into cascade stages after its filling depend on variable parameters and are not equal to its concentration on initial isotope mixture (or feed flow of cascade). This assumption is used earlier any researchers for modeling such nonstationary process as set of steady-state concentration of isotopes into cascade. Article shows physical laws of isotope distribution into cascade stage after its filling. It's shown that varying each parameters of cascade (feed flow rate, feed stage number or cascade stage number) it is possible to change isotope concentration on output cascade flows (light or heavy fraction) for reduction of duration of further process to set of steady-state concentration of isotopes into cascade.

Comparison of aroma volatiles in commercial Merlot and Cabernet Sauvignon wines using gas chromatography-olfactometry and gas chromatography-mass spectrometry.

Science.gov (United States)

Gürbüz, Ozan; Rouseff, June M; Rouseff, Russell L

2006-05-31

Seventy-four aroma active compounds were observed in Merlot and Cabernet Sauvignon wines produced in California and Australia. Volatiles were sampled using solid phase microextraction and analyzed using time-intensity gas chromatography-olfactometry and gas chromatography-mass spectrometry (GC-MS). The most intense odorants were 3-methyl-1-butanol, 3-hydroxy-2-butanone, octanal, ethyl hexanoate, ethyl 2-methylbutanoate, beta-damascenone, 2-methoxyphenol, 4-ethenyl-2-methoxy-phenol, ethyl 3-methylbutanoate, acetic acid, and 2-phenylethanol. Aroma compounds were classified according to their aroma descriptor similarity and summed into nine distinct categories consisting of fruity, sulfury, caramel/cooked, spicy/peppery, floral, earthy, pungent/chemical, woody, and green/vegetative/fatty. Both Merlot and Cabernet Sauvignon wines were characterized by high fruity, caramel, green, and earthy aroma totals. Although there were distinct quantitative differences between Merlot and Cabernet wines, the relative aroma category profiles of the four wines were similar. Of the 66 volatiles identified by GC-MS, 28 were esters and 19 were minor alcohols. Between 81 and 88% of the total MS total ion chromatogram peak areas from each wine type were produced from only eight compounds: ethanol, ethyl octanoate, ethyl decanoate, ethyl acetate, 3-methyl-1-butanol, ethyl hexanoate, diethyl succinate, and 2-phenylethanol. Merlot wines from both Australia and California contained 4-5 times more ethyl octanoate than Cabernet Sauvignon wines from the same sources.

Novel method for measurement of glutathione kinetics in neonates using liquid chromatography coupled to isotope ratio mass spectrometry

NARCIS (Netherlands)

Schierbeek, Henk; te Braake, Frans; Godin, Jean-Philippe; Fay, Laurent-Bernard; van Goudoever, Johannes B.

2007-01-01

A novel analytical method using liquid chromatography coupled to isotope ratio mass spectrometry (LC/IRMS) was developed for measuring the fractional synthesis rate (FSR) of glutathione (GSH) in neonates after infusion of [1-(13)C]-glycine as a tracer. After transformation of GSH into GSSG, its

Comprehensive two-dimensional gas chromatography applied to illicit drug analysis.

Science.gov (United States)

Mitrevski, Blagoj; Wynne, Paul; Marriott, Philip J

2011-11-01

Multidimensional gas chromatography (MDGC), and especially its latest incarnation--comprehensive two-dimensional gas chromatography (GC × GC)--have proved advantageous over and above classic one-dimensional gas chromatography (1D GC) in many areas of analysis by offering improved peak capacity, often enhanced sensitivity and, especially in the case of GC × GC, the unique feature of 'structured' chromatograms. This article reviews recent advances in MDGC and GC × GC in drug analysis with special focus on ecstasy, heroin and cocaine profiling. Although 1D GC is still the method of choice for drug profiling in most laboratories because of its simplicity and instrument availability, GC × GC is a tempting proposition for this purpose because of its ability to generate a higher net information content. Effluent refocusing due to the modulation (compression) process, combined with the separation on two 'orthogonal' columns, results in more components being well resolved and therefore being analytically and statistically useful to the profile. The spread of the components in the two-dimensional plots is strongly dependent on the extent of retention 'orthogonality' (i.e. the extent to which the two phases possess different or independent retention mechanisms towards sample constituents) between the two columns. The benefits of 'information-driven' drug profiling, where more points of reference are usually required for sample differentiation, are discussed. In addition, several limitations in application of MDGC in drug profiling, including data acquisition rate, column temperature limit, column phase orthogonality and chiral separation, are considered and discussed. Although the review focuses on the articles published in the last decade, a brief chronological preview of the profiling methods used throughout the last three decades is given.

Separation of krypton from dissolver off-gas of a reprocessing plant using preparative gas chromatography

International Nuclear Information System (INIS)

Matoni, M.

1984-02-01

Kr-85 can be separated from the pre-purified purge air in the final processing step of the purification phase for dissolver off-gases of a reprocessing plant with the aid of preparative gas chromatography. Activated carbon adsorbers in combination with helium as carrier gas permits maximum gas mixture through-flow. A separation temperature of 30 0 C is considered optimal. An adsorbent volume of 40 dm 3 is necessary for processing the residual gas flow of 2.5 Nm 3 /h; the adsorbent is divided between 2 columns linked in series each of which are 2 m long with an internal diameter of 100 mm. The helium flow required is five times greater than the off-gas flow. The degree of purity for krypton is greater than 90% for a decontamination factor of greater than 1000. (orig./HP) [de

Determination of urea kinetics by isotope dilution with [C-13]urea and gas chromatography isotope ratio mass spectrometry (GC-IRMS) analysis

NARCIS (Netherlands)

Kloppenburg, Wybe; Wolthers, BG; Stellaard, F; Elzinga, H; Tepper, T; deJong, PE; Huisman, RM

1. Stable urea isotopes can be used to study urea kinetics in humans, The use of stable urea isotopes far studying urea kinetic parameters in humans on a large scale is hampered by the high costs of the labelled material, We devised a urea dilution for measurement of the distribution volume,

Demonstration of conjugated dopamine in monkey CSF by gas chromatography-mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Elchisak, M A; Powers, K H; Ebert, M H

1982-09-01

A method for measuring unconjugated and conjugated dopamine in body tissues and fluids is described. Conjugated dopamine was hydrolyzed in acid to unconjugated dopamine, separated from the sample matrix by alumina chromatography, and assayed by gas chromatography-mass spectrometry. Conjugated dopamine was detected in greater concentrations than unconjugated dopamine in CSF taken from lateral ventricle or thecal sac of the Rhesus monkey. Haloperidol administration did not increase the levels of conjugated dopamine in lumbar CSF.

Data on acetic acid–methanol–methyl acetate–water mixture analysised by dual packed column Gas Chromatography

Directory of Open Access Journals (Sweden)

Mallaiah Mekala

2018-06-01

Full Text Available The composition of multicomponent determination by colorimetric titration is difficult. This complexity is easily overcome by using Gas Chromatography technique instead of wet method for multi-component mixture analysis. In Gas Chromatography, first the standard chart is prepared by using the known amount sample concentration as the reference. Once calibration chart is prepared the unknown sample concentration easily measured by using the standard chart. In the present study a standard calibration chart developed for the four component system of acetic acid–methanol–methyl acetate–water. The samples were taken at various concentrations of all components and different chromatograms obtained under various concentrations respectively. The method of optimization was first carried out to get the sharp peaks of individual components and binary pairs also. By using those conditions, the multi components concentrations were estimated. From the present results, the area under gas chromatogram is linearly varying with mole% of the components compared to mass%. Keywords: Gas Chromatography, Esterification, Calibration, Retention time, Optimization

[Analysis of hydrogen isotopes by gas chromatography using a MnCl2 coated γ-Al2O3 capillary packed column].

Science.gov (United States)

Chen, Ping; Fu, Xiaolong; Hu, Peng; Xiao, Chengjian; Ren, Xingbi; Xia, Xiulong; Wang, Heyi

2017-07-08

The conventional packed column gas chromatographic analysis of hydrogen isotopes has low column efficiency, broad peak and long retention time. In this work, a γ -Al 2 O 3 with MnCl 2 coated capillary packed column was tested at cryogenic temperature. The systematic column efficiency analysis and the hydrogen isotopes analytical technique research had been carried out. The results showed that, the γ -Al 2 O 3 with MnCl 2 coating could greatly improve the surface degree of order, pore structure and adsorption properties. Also the o -H 2 peak and p -H 2 peak were eluted in a single area. The γ -Al 2 O 3 with MnCl 2 coating was packed into a 0.53 mm inner diameter and 1.0 m long fused silica capillary column. It had a good linear relationship used this column with thermal conductivity detector (TCD) to detect the volume concentrations of hydrogen isotopes from 1 to 10 mL/L, and the relative error was less than 5% for low concentration sample testing. For H 2 , HD and D 2 , the retention times can be shortened to 39, 46 and 60 s, respectively. The limits of detection were reduced to 0.046, 0.067 and 0.072 mL/L, respectively. Compared with conventional packed column, capillary packed column had sharper peak form, higher separation degree of adjacent components, shorter retention time and lower detection limits. The above results indicate that the capillary packed column with TCD detector can be used for fast detection of low concentration of hydrogen isotopes and their online analysis.

Mathematical Modeling of Nonstationary Separation Processes in Gas Centrifuge Cascade for Separation of Multicomponent Isotope Mixtures

OpenAIRE

Orlov Alexey; Ushakov Anton; Sovach Victor

2016-01-01

This article presents results of development of the mathematical model of nonstationary separation processes occurring in gas centrifuge cascades for separation of multicomponent isotope mixtures. This model was used for the calculation parameters of gas centrifuge cascade for separation of germanium isotopes. Comparison of obtained values with results of other authors revealed that developed mathematical model is adequate to describe nonstationary separation processes in gas centrifuge casca...

Nicotine, acetanilide and urea multi-level2H-,13C- and15N-abundance reference materials for continuous-flow isotope ratio mass spectrometry

Science.gov (United States)

Schimmelmann, A.; Albertino, A.; Sauer, P.E.; Qi, H.; Molinie, R.; Mesnard, F.

2009-01-01

Accurate determinations of stable isotope ratios require a calibration using at least two reference materials with different isotopic compositions to anchor the isotopic scale and compensate for differences in machine slope. Ideally, the S values of these reference materials should bracket the isotopic range of samples with unknown S values. While the practice of analyzing two isotopically distinct reference materials is common for water (VSMOW-SLAP) and carbonates (NBS 19 and L-SVEC), the lack of widely available organic reference materials with distinct isotopic composition has hindered the practice when analyzing organic materials by elemental analysis/isotope ratio mass spectrometry (EA-IRMS). At present only L-glutamic acids USGS40 and USGS41 satisfy these requirements for ??13C and ??13N, with the limitation that L-glutamic acid is not suitable for analysis by gas chromatography (GC). We describe the development and quality testing of (i) four nicotine laboratory reference materials for on-line (i.e. continuous flow) hydrogen reductive gas chromatography-isotope ratio mass-spectrometry (GC-IRMS), (ii) five nicotines for oxidative C, N gas chromatography-combustion-isotope ratio mass-spectrometry (GC-C-IRMS, or GC-IRMS), and (iii) also three acetanilide and three urea reference materials for on-line oxidative EA-IRMS for C and N. Isotopic off-line calibration against international stable isotope measurement standards at Indiana University adhered to the 'principle of identical treatment'. The new reference materials cover the following isotopic ranges: ??2Hnicotine -162 to -45%o, ??13Cnicotine -30.05 to +7.72%, ?? 15Nnicotine -6.03 to +33.62%; ??15N acetanilide +1-18 to +40.57%; ??13Curea -34.13 to +11.71%, ??15Nurea +0.26 to +40.61% (recommended ?? values refer to calibration with NBS 19, L-SVEC, IAEA-N-1, and IAEA-N-2). Nicotines fill a gap as the first organic nitrogen stable isotope reference materials for GC-IRMS that are available with different ??13N

Geochemical and strontium isotope characterization of produced waters from Marcellus Shale natural gas extraction.

Science.gov (United States)

Chapman, Elizabeth C; Capo, Rosemary C; Stewart, Brian W; Kirby, Carl S; Hammack, Richard W; Schroeder, Karl T; Edenborn, Harry M

2012-03-20

Extraction of natural gas by hydraulic fracturing of the Middle Devonian Marcellus Shale, a major gas-bearing unit in the Appalachian Basin, results in significant quantities of produced water containing high total dissolved solids (TDS). We carried out a strontium (Sr) isotope investigation to determine the utility of Sr isotopes in identifying and quantifying the interaction of Marcellus Formation produced waters with other waters in the Appalachian Basin in the event of an accidental release, and to provide information about the source of the dissolved solids. Strontium isotopic ratios of Marcellus produced waters collected over a geographic range of ~375 km from southwestern to northeastern Pennsylvania define a relatively narrow set of values (ε(Sr)(SW) = +13.8 to +41.6, where ε(Sr) (SW) is the deviation of the (87)Sr/(86)Sr ratio from that of seawater in parts per 10(4)); this isotopic range falls above that of Middle Devonian seawater, and is distinct from most western Pennsylvania acid mine drainage and Upper Devonian Venango Group oil and gas brines. The uniformity of the isotope ratios suggests a basin-wide source of dissolved solids with a component that is more radiogenic than seawater. Mixing models indicate that Sr isotope ratios can be used to sensitively differentiate between Marcellus Formation produced water and other potential sources of TDS into ground or surface waters.

Determination of 4-Chloroindole-3-Acetic Acid Methyl Ester in Lathyrus Vicia and Pisum by Gas Chromatography - Mass Spectrometry

DEFF Research Database (Denmark)

Engvild, Kjeld Christensen; Egsgaard, Helge; Larsen, Elfinn

1980-01-01

4-Chloroindole-3-acetic acid methyl ester was identified unequivocally in Lathyrus latifolius L., Vicia faba L. and Pisum sativum L. by thin layer chromatography, gas chromatography and mass spectrometry. The gas chromatographic system was able to separate underivatized chloroindole-3-acetic acid...... methyl ester isomers. The quantitative determination of 4-chloroindole-3-acetic acid methyl ester in immature seeds of these three species was performed by gas chromatography – mass spectrometry using deuterium labelled 4-chloro-indole-3-acetic acid methyl ester as an internal standard. P. sativum...

Molecular analysis of sulphur-rich brown coals by flash pyrolysis-gas chromatography-mass spectrometry: The type III-S kerogen

NARCIS (Netherlands)

Sinninghe Damsté, J.S.; Las Heras, F.X.C. de; Leeuw, J.W. de

1992-01-01

The molecular composition of five brown coals from three different basins (Maestrazgo, Mequinenza and Rubielos) in Spain was investigated by flash pyrolysis-gas chromatography and flash pyrolysis-gas chromatography-mass spectrometry. In these techniques, the macromolecular material is thermally

Utilization of stable isotopes for characterizing an underground gas generator; Utilisation des isotopes stables pour caracteriser un gazogene souterrain

Energy Technology Data Exchange (ETDEWEB)

Pirard, J P; Antenucci, D; Renard, X [Liege Univ. (Belgium); Letolle, R [Paris-6 Univ., 75 (France)

1994-12-31

The principles of isotopic exchange and isotope ratio result interpretation are first reviewed; then, in the framework of an underground coal gasification project in Belgium, experiments and modelling of the underground gas generator have been carried out: isotopic abundances of carbon, hydrogen and oxygen have been measured in the gasifying agent (O{sub 2}, H{sub 2}O) and in the effluent (CO{sub 2}, CO, H{sub 2}, H{sub 2}O, CH{sub 4}, O{sub 2}, heavy oils and various organic and mineral substances). Gasification kinetics and temperatures have been evaluated and isotope application to thermometry is discussed. 1 fig., 9 refs.

Oxygen isotope exchange between refractory inclusion in allende and solar nebula Gas

Science.gov (United States)

Yurimoto; Ito; Nagasawa

1998-12-04

A calcium-aluminum-rich inclusion (CAI) from the Allende meteorite was analyzed and found to contain melilite crystals with extreme oxygen-isotope compositions ( approximately 5 percent oxygen-16 enrichment relative to terrestrial oxygen-16). Some of the melilite is also anomalously enriched in oxygen-16 compared with oxygen isotopes measured in other CAIs. The oxygen isotopic variation measured among the minerals (melilite, spinel, and fassaite) indicates that crystallization of the CAI started from oxygen-16-rich materials that were probably liquid droplets in the solar nebula, and oxygen isotope exchange with the surrounding oxygen-16-poor nebular gas progressed through the crystallization of the CAI. Additional oxygen isotope exchange also occurred during subsequent reheating events in the solar nebula.

On the enrichment of low-abundant isotopes of light chemical elements by gas centrifuges

International Nuclear Information System (INIS)

Borisevich, V.D.; Morozov, O.E.; Zaozerskiy, Yu.P.; Shmelev, G.M.; Shipilov, Yu.D.

2000-01-01

A brief review of the main areas for the application of the isotopes 15 N and 13 C is made. Separation of the nitrogen isotopes in a single gas centrifuge in the form of pure nitrogen, ammonia, and trifluoride of nitrogen as well as the carbon isotopes in the form of carbon dioxide has been studied by means of numerical simulation. The parameters of the centrifugal machine investigated were close to the parameters of the Iguassu machine. The dependence of the efficiency criterion versus the basic parameters of the separation process has been explored in the computational experiments. Comparisons of the calculated results with the experimental data have shown good agreement. The results obtained have demonstrated the possibility of using gas centrifuge technology to enrich successfully the low-abundant isotopes of light chemical elements

Gas Chromatography/mass Spectrometry Analysis of Exhaled Leukotrienes in Asthmatic Patients

Czech Academy of Sciences Publication Activity Database

Čáp, P.; Chládek, J.; Pehal, F.; Malý, Marek; Petrů, V.; Barnes, P.J.; Montuschi, P.

2004-01-01

Roč. 59, č. 6 (2004), s. 465-470 ISSN 0040-6376 Source of funding: V - iné verejné zdroje Keywords : asthma * breath condensate * gas chromatography/mass spectrometry * leukotrienes Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 5.040, year: 2004

Mathematical model of nonstationary hydraulic processes in gas centrifuge cascade for separation of multicomponent isotope mixtures

OpenAIRE

Orlov, Aleksey Alekseevich; Ushakov, Anton; Sovach, Victor

2017-01-01

The article presents results of development of a mathematical model of nonstationary hydraulic processes in gas centrifuge cascade for separation of multicomponent isotope mixtures. This model was used for the calculation parameters of gas centrifuge cascade for separation of silicon isotopes. Comparison of obtained values with results of other authors revealed that developed mathematical model is adequate to describe nonstationary hydraulic processes in gas centrifuge cascades for separation...

Determination of vaporization enthalpies of polychlorinated biphenyls by correlation gas chromatography.

Science.gov (United States)

Puri, S; Chickos, J S; Welsh, W J

2001-04-01

The vaporization enthalpies of 16 polychlorinated biphenyls have been determined by correlation gas chromatography. This study was prompted by the realization that the vaporization enthalpy of the standard compounds used in previous studies, octadecane and eicosane, were values measured at 340 and 362 K, respectively, rather than at 298 K. Adjustment to 298 K amounts to a 7-8 kJ/mol increment in the values. With the inclusion of this adjustment, vaporization enthalpies evaluated by correlation gas chromatography are in good agreement with the values determined previously in the literature. The present results are based on the vaporization enthalpies of several standards whose values are well established in the literature. The standards include a variety of n-alkanes and various chlorinated hydrocarbons. The vaporization enthalpies of PCBs increased with the number of chlorine atoms and were found to be larger for meta- and para-substituted polychlorinated biphenyls.

Evaluation of three gas chromatography and two direct mass spectrometry techniques for aroma analysis of dried red bell peppers

NARCIS (Netherlands)

Ruth, van S.M.; Boscaini, E.; Mayr, D.; Pugh, J.; Posthumus, M.A.

2003-01-01

Three gas chromatography methods and two direct mass spectrometry techniques were compared for the analysis of the aroma of rehydrated diced red bell peppers. Gas chromatography methods included systems with olfactometry detection (GC-O), flame ionisation detection (GC-FID) and mass spectrometry

Determination of basic azaarenes and polynuclear aromatic hydrocarbons in airborne particulate matter by gas chromatography

DEFF Research Database (Denmark)

Nielsen, Torben; Clausen, Peraxel; Jensen, Finn Palmgren

1986-01-01

phase (adjusted to pH 14 with potassium hydroxide) with dichloromethane, and determined by capillary gas chromatography (g.c.) with a nitrogen-sensitive detector. The PAH in the toluene phase are isolated by means of semipreparative high-performance liquid chromatography and liquid-liquid extraction...

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

Science.gov (United States)

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.

Characterization of Volatile Compounds from Ethnic Agave Alcoholic Beverages by Gas Chromatography-Mass Spectrometry

Directory of Open Access Journals (Sweden)

Pilar Escalante-Minakata

2008-01-01

Full Text Available Ethnic Agave alcoholic beverages such as raicilla, sisal, tequila, mezcal, bacanora, sotol and pulque have been analyzed by gas chromatography and headspace solid-phase microextraction- gas chromatography-mass spectrometry (HS-SPME-GC-MS. There were 105 compounds identified, eleven were classified as major compounds and the others were classified as minor compounds. Seventeen minor compounds could be used as authenticity markers since they were beverage specific. Cluster analysis (CA showed that Agave alcoholic beverages could be distinguished by multivariate analysis of major compounds; however, the analysis of minor compounds provided a better fingerprinting.

Rapid and Precise Measurement of Serum Branched-Chain and Aromatic Amino Acids by Isotope Dilution Liquid Chromatography Tandem Mass Spectrometry

OpenAIRE

Yang, Ruiyue; Dong, Jun; Guo, Hanbang; Li, Hongxia; Wang, Shu; Zhao, Haijian; Zhou, Weiyan; Yu, Songlin; Wang, Mo; Chen, Wenxiang

2013-01-01

BACKGROUND: Serum branched-chain and aromatic amino acids (BCAAs and AAAs) have emerged as predictors for the future development of diabetes and may aid in diabetes risk assessment. However, the current methods for the analysis of such amino acids in biological samples are time consuming. METHODS: An isotope dilution liquid chromatography tandem mass spectrometry (ID-LC/MS/MS) method for serum BCAAs and AAAs was developed. The serum was mixed with isotope-labeled BCAA and AAA internal standar...

Enthalpy of Vaporization by Gas Chromatography: A Physical Chemistry Experiment

Science.gov (United States)

Ellison, Herbert R.

2005-01-01

An experiment is conducted to measure the enthalpy of vaporization of volatile compounds like methylene chloride, carbon tetrachloride, and others by using gas chromatography. This physical property was measured using a very tiny quantity of sample revealing that it is possible to measure the enthalpies of two or more compounds at the same time.

Carbon (14C,13C) and hydrogen (D) isotope measurements on atmospheric methane and its sources (sinks)

International Nuclear Information System (INIS)

Levin, I.; Doerr, H.

1991-07-01

Concentrations and isotope ratios ( 13 C/ 12 C and D/H) of atmospheric methane and methane from other sources were determined by gas chromatography and mass spectroscopy in specially prepared samples. The results were used for assessing the atmospheric methane inventory. (BBR) [de

Separation of polybrominated diphenyl ethers in fish for compound-specific stable carbon isotope analysis

Energy Technology Data Exchange (ETDEWEB)

Zeng, Yan-Hong [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Graduate University of Chinese Academy of Sciences, Beijing, 100049 (China); Luo, Xiao-Jun, E-mail: luoxiaoj@gig.ac.cn [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Chen, Hua-Shan; Wu, Jiang-Ping; Chen, She-Jun; Mai, Bi-Xian [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China)

2012-05-15

A separation and isotopic analysis method was developed to accurately measure the stable carbon isotope ratios of polybrominated diphenyl ethers (PBDEs) with three to six substituted bromine atoms in fish samples. Sample extracts were treated with concentrated sulfuric acid to remove lipids, purified using complex silica gel column chromatography, and finally processed using alumina/silica (Al/Si) gel column chromatography. The purities of extracts were verified by gas chromatography and mass spectrometry (GC-MS) in the full-scan mode. The average recoveries of all compounds across the purification method were between 60% and 110%, with the exception of BDE-154. The stable carbon isotopic compositions of PBDEs can be measured with a standard deviation of less than 0.5 Per-Mille-Sign . No significant isotopic fraction was found during the purification of the main PBDE congeners. A significant change in the stable carbon isotope ratio of BDE-47 was observed in fish carcasses compared to the original isotopic signatures, implying that PBDE stable carbon isotopic compositions can be used to trace the biotransformation of PBDEs in biota. - Highlights: Black-Right-Pointing-Pointer A method for the purification of PBDEs for CSIA was developed. Black-Right-Pointing-Pointer The {delta}{sup 13}C of PBDE congeners can be measured with a standard deviation of less than 0.5 Per-Mille-Sign . Black-Right-Pointing-Pointer Common carp were exposed to a PBDE mixture to investigate debromination. Black-Right-Pointing-Pointer Ratios of the {delta}{sup 13}C values can be used to trace the debromination of PBDE in fish.

Pilot study on feasibility of application of gas chromatography for the assessment of acrylamide concentration in sewage sludge.

Science.gov (United States)

Włodarczyk, Elżbieta; Próba, Marta; Wolny, Lidia; Wojtal, Łukasz

2014-01-01

The aim of this study was to determine the possibility of using gas chromatography to measurement of the acrylamide concentration in sewage sludge. Acrylamide, as a toxic substance, is not indifferent to human health, but it is used in the production of plastics, dyes, adhesives, cosmetics, mortar, as well as a coagulant for water treatment, wastewater or sewage sludge conditioning. Determination of acrylamide by gas chromatography was based on standard: EPA Method 8032A "Acrylamid by gas chromatography." It consists of a bromination reaction of the compound in the presence of dibromopropendial derivative, a triple extraction with the ethyl acetate, a concentration of the eluate sample up to the 1 ml volume, and an analysis by the gas chromatography using an electron capture detector (ECD). The acrylamide concentration of was calculated according to the formula presented in the mentioned standard. All samples were performed twice (the difference between the results was not greater than 10%), and the average value of the four samples was 17.64 µg/L(-1). The presence of acrylamide in sewage sludge has been confirmed.

Identification of bound alcohols in soil humic acids by gas chromatography-mass spectrometry

OpenAIRE

Berthier , Gersende; Dou , Sen; Peakman , Torren; Lichtfouse , Eric

2000-01-01

International audience; Humic acids are complex, partly macromolecular, yellow-brownish substances occurring in soils, waters and sediments. In order to shed some light on their molecular structure, crop humic acids were cleaved by alkaline hydrolysis (KOH). The products were fractionated by thin layer chromatography to give mono-alcohols which were analysed as acetate derivatives by gas chromatography coupled to mass spectrometry. Linear alcohols, sterols, stanols and plant-derived triterpen...

Silica, alumina and aluminosilicates as solid stationary phases in gas chromatography

Directory of Open Access Journals (Sweden)

S. Faramawy

2016-09-01

Full Text Available Silica, alumina and Aluminosilicates of different Si/Al ratios were prepared by conventional precipitation or co-precipitation methods and then subjected to thermal treatment at 800 °C. The parent and thermally treated materials were characterized by means of FTIR, SEM and thermal analysis (DTA and TGA in order to elucidate the main structural properties. Surface textural characteristics were investigated by means of nitrogen adsorption–desorption isotherms at −196 °C. Pore size distribution curves indicated the presence of mesopores (10–150 Å exhibiting maxima at 35 Å. The maxima were shifted toward higher values by increasing the alumina content. Thermodynamic parameters, ΔH, ΔG and ΔS, were determined by means of inverse gas chromatography using n-hexane as a probe. The untreated and thermally treated materials were tested as solid stationary phases in gas chromatography. The separation efficiency of various non polar and polar compounds was explained in terms of surface texture and thermodynamic parameters.

Gas chromatography-vacuum ultraviolet spectroscopy for analysis of fatty acid methyl esters.

Science.gov (United States)

Fan, Hui; Smuts, Jonathan; Bai, Ling; Walsh, Phillip; Armstrong, Daniel W; Schug, Kevin A

2016-03-01

A new vacuum ultraviolet (VUV) detector for gas chromatography was recently developed and applied to fatty acid methyl ester (FAME) analysis. VUV detection features full spectral acquisition in a wavelength range of 115-240nm, where virtually all chemical species absorb. VUV absorption spectra of 37 FAMEs, including saturated, monounsaturated, and polyunsaturated types were recorded. Unsaturated FAMEs show significantly different gas phase absorption profiles than saturated ones, and these classes can be easily distinguished with the VUV detector. Another advantage includes differentiating cis/trans-isomeric FAMEs (e.g. oleic acid methyl ester and linoleic acid methyl ester isomers) and the ability to use VUV data analysis software for deconvolution of co-eluting signals. As a universal detector, VUV also provides high specificity, sensitivity, and a fast data acquisition rate, making it a powerful tool for fatty acid screening when combined with gas chromatography. The fatty acid profile of several food oil samples (olive, canola, vegetable, corn, sunflower and peanut oils) were analyzed in this study to demonstrate applicability to real world samples. Copyright © 2015 Elsevier Ltd. All rights reserved.

Cromatografia unificada Unified chromatography

Directory of Open Access Journals (Sweden)

Carin von Mühlen

2004-10-01

Full Text Available The scope of this study encompasses an overview of the principles of unified chromatography as well as the principles of chromatographic techniques as applied to unified systems, which include gas chromatography, liquid chromatography, supercritical fluid chromatography, high temperature and high pressure liquid chromatography, micro-liquid chromatography, enhanced fluidity chromatography, and solvating gas chromatography. Theoretical considerations and individual instrumental parameters such as mobile phase, sample introduction system, columns, and detection system are also discussed. Future applications of this separation approach are discussed.

Establishment of analysis method for methane detection by gas chromatography

Science.gov (United States)

Liu, Xinyuan; Yang, Jie; Ye, Tianyi; Han, Zeyu

2018-02-01

The study focused on the establishment of analysis method for methane determination by gas chromatography. Methane was detected by hydrogen flame ionization detector, and the quantitative relationship was determined by working curve of y=2041.2x+2187 with correlation coefficient of 0.9979. The relative standard deviation of 2.60-6.33% and the recovery rate of 96.36%∼105.89% were obtained during the parallel determination of standard gas. This method was not quite suitable for biogas content analysis because methane content in biogas would be over the measurement range in this method.

Quantitative analysis of target components by comprehensive two-dimensional gas chromatography

NARCIS (Netherlands)

Mispelaar, V.G. van; Tas, A.C.; Smilde, A.K.; Schoenmakers, P.J.; Asten, A.C. van

2003-01-01

Quantitative analysis using comprehensive two-dimensional (2D) gas chromatography (GC) is still rarely reported. This is largely due to a lack of suitable software. The objective of the present study is to generate quantitative results from a large GC x GC data set, consisting of 32 chromatograms.

Protein Stable Isotope Fingerprinting (P-SIF): Multidimensional Protein Chromatography Coupled to Stable Isotope-Ratio Mass Spectrometry

Science.gov (United States)

Pearson, A.; Bovee, R. J.; Mohr, W.; Tang, T.

2012-12-01

As metagenomics increases our insight into microbial community diversity and metabolic potential, new approaches are required to determine the biogeochemical expression of this potential within ecosystems. Because stable isotopic analysis of the major bioactive elements (C, N) has been used historically to map flows of substrates and energy among macroscopic food webs, similar principles may apply to microbes. To address this challenge, we have developed a new analytical approach called Protein Stable Isotope Fingerprinting (P-SIF). P-SIF generates natural stable isotopic fingerprints of microbial individual or community proteomes. The main advantage of P-SIF is the potential to bridge the gap between diversity and function, thereby providing a window into the "black box" of environmental microbiology and helping to decipher the roles of uncultivated species. Our method implements a three-way, orthogonal scheme to separate mixtures of whole proteins into subfractions dominated by single or closely-related proteins. Protein extracts first are isoelectrically focused in a gel-free technique that yields 12 fractions separated over a gradient of pH 3-10. Each fraction then is separated by size-exclusion chromatography into 20 pools, ranging from >100kD to ~10kD. Finally, each of these pools is subjected to HPLC and collected in 40 time-slices based on protein hydrophobicity. Theoretical calculation reveals that the true chromatographic resolution of the total scheme is 5000, somewhat less than the 9600 resulting fractions. High-yielding fractions are subjected to δ13C analysis by spooling-wire microcombustion irMS (SWiM-irMS) optimized for samples containing 1-5 nmol carbon. Here we will present the method, results for a variety of pure cultures, and preliminary data for a sample of mixed environmental proteins. The data show the promise of this method for unraveling the metabolic complexity hidden within microbial communities.

Quality control of residual solvents in [18F]FDG preparations by gas chromatography

International Nuclear Information System (INIS)

Lee, Hak Jeong; Jeong, Jae Min; Lee, Yun Sang; Kim, Hyung Woo; Chang, Young Soo; Lee, Dong Soo; Chung, June Key; Lee, Myung Chul

2007-01-01

Analysis of volatile organic solvents in 2-deoxy-2[ 18 F] fluoro-D-glucose ([ 18 F]FDG) preparations was performed by gas chromatography (GC), in accordance with USP. Analyses were carried out on a Hewlett-Packard 6890 gas chromatography equipped with an FID. We determined the amounts of ethanol and acetonitrile on every batch of our routine [ 18 F]FDG preparations, ranging between 5000 ppm and 100 ppm. In our routine preparation of [ 18 F]FDG, the amount of acetonitrile and ethanol in the final product were well below the maximum allowable limit described in the USP. Our [ 18 F]FDG preparations were in accordance with the suggested USP maximum allowable levels of the quality control analysis of volatile organic compounds

Metal-Organic Framework Thin Films as Stationary Phases in Microfabricated Gas-Chromatography Columns.

Energy Technology Data Exchange (ETDEWEB)

Read, Douglas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sillerud, Colin Halliday [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2016-01-01

The overarching goal of this project is to integrate Sandia's microfabricated gas-chromatography ( GC) columns with a stationary phase material that is capable of retaining high-volatility chemicals and permanent gases. The successful integration of such a material with GCs would dramatically expand the repertoire of detectable compounds for Sandia's various microanalysis systems. One such promising class of candidate materials is metal-organic frameworks (MOFs). In this report we detail our methods for controlled deposition of HKUST-1 MOF stationary phases within GC columns. We demonstrate: the chromatographic separation of natural gas; a method for determining MOF film thickness from chromatography alone; and the first-reported GC x GC separation of natural gas -- in general -- let alone for two disparate MOF stationary phases. In addition we determine the fundamental thermodynamic constant for mass sorption, the partition coefficient, for HKUST-1 and several light hydrocarbons and select toxic industrial chemicals.

Gas chromatography of alkylphosphonic and dialkylphosphinic acids

International Nuclear Information System (INIS)

Gasco, L.; Barrera, R.; Ramirez, A.; Martin Munoz, N.

1978-01-01

After carrying out an optimization study on the separation conditions for the TMS-derivatives, of the hexyl-, cyclohexyl-, heptyl-, and octyl-phosphonic acids; dihexyl-, dicyclohexyl-, heptyl-, and octyl-phosphinic acids, and dioctylphosphine oxide, their retention indices (I) at two temperatures and on the 0V-1 and 0V-17 stationary phase were determined. Correlations between I and molecular structure were established. Calibration factors of these compounds in the flame ionization detector were studied, and the results analized taking into account the variables afecting the quantitative results. These results were unbiased but they had a lower precission than usually achieveble in gas chromatography. (author)

Occurrence and origin of methane in groundwater in Alberta (Canada): Gas geochemical and isotopic approaches

International Nuclear Information System (INIS)

Humez, P.; Mayer, B.; Ing, J.; Nightingale, M.; Becker, V.; Kingston, A.; Akbilgic, O.; Taylor, S.

2016-01-01

To assess potential future impacts on shallow aquifers by leakage of natural gas from unconventional energy resource development it is essential to establish a reliable baseline. Occurrence of methane in shallow groundwater in Alberta between 2006 and 2014 was assessed and was ubiquitous in 186 sampled monitoring wells. Free and dissolved gas sampling and measurement approaches yielded comparable results with low methane concentrations in shallow groundwater, but in 28 samples from 21 wells methane exceeded 10 mg/L in dissolved gas and 300,000 ppmv in free gas. Methane concentrations in free and dissolved gas samples were found to increase with well depth and were especially elevated in groundwater obtained from aquifers containing coal seams and shale units. Carbon isotope ratios of methane averaged − 69.7 ± 11.1‰ (n = 63) in free gas and − 65.6 ± 8.9‰ (n = 26) in dissolved gas. δ"1"3C values were not found to vary with well depth or lithology indicating that methane in Alberta groundwater was derived from a similar source. The low δ"1"3C values in concert with average δ"2H_C_H_4 values of − 289 ± 44‰ (n = 45) suggest that most methane was of biogenic origin predominantly generated via CO_2 reduction. This interpretation is confirmed by dryness parameters typically > 500 due to only small amounts of ethane and a lack of propane in most samples. Comparison with mud gas profile carbon isotope data revealed that methane in the investigated shallow groundwater in Alberta is isotopically similar to hydrocarbon gases found in 100–250 meter depths in the WCSB and is currently not sourced from thermogenic hydrocarbon occurrences in deeper portions of the basin. The chemical and isotopic data for methane gas samples obtained from Alberta groundwater provide an excellent baseline against which potential future impact of deeper stray gases on shallow aquifers can be assessed. - Highlights: • Analysis of gas geochemical data from 186 monitoring wells in

Occurrence and origin of methane in groundwater in Alberta (Canada): Gas geochemical and isotopic approaches

Energy Technology Data Exchange (ETDEWEB)

Humez, P., E-mail: phumez@ucalgary.ca [Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4 (Canada); Mayer, B.; Ing, J.; Nightingale, M.; Becker, V.; Kingston, A. [Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4 (Canada); Akbilgic, O. [Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4 (Canada); UTHSC-ORNL Center for Biomedical Informatics, 910 Madison Avenue, Memphis, TN, 38104 (United States); Taylor, S. [Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4 (Canada)

2016-01-15

To assess potential future impacts on shallow aquifers by leakage of natural gas from unconventional energy resource development it is essential to establish a reliable baseline. Occurrence of methane in shallow groundwater in Alberta between 2006 and 2014 was assessed and was ubiquitous in 186 sampled monitoring wells. Free and dissolved gas sampling and measurement approaches yielded comparable results with low methane concentrations in shallow groundwater, but in 28 samples from 21 wells methane exceeded 10 mg/L in dissolved gas and 300,000 ppmv in free gas. Methane concentrations in free and dissolved gas samples were found to increase with well depth and were especially elevated in groundwater obtained from aquifers containing coal seams and shale units. Carbon isotope ratios of methane averaged − 69.7 ± 11.1‰ (n = 63) in free gas and − 65.6 ± 8.9‰ (n = 26) in dissolved gas. δ{sup 13}C values were not found to vary with well depth or lithology indicating that methane in Alberta groundwater was derived from a similar source. The low δ{sup 13}C values in concert with average δ{sup 2}H{sub CH4} values of − 289 ± 44‰ (n = 45) suggest that most methane was of biogenic origin predominantly generated via CO{sub 2} reduction. This interpretation is confirmed by dryness parameters typically > 500 due to only small amounts of ethane and a lack of propane in most samples. Comparison with mud gas profile carbon isotope data revealed that methane in the investigated shallow groundwater in Alberta is isotopically similar to hydrocarbon gases found in 100–250 meter depths in the WCSB and is currently not sourced from thermogenic hydrocarbon occurrences in deeper portions of the basin. The chemical and isotopic data for methane gas samples obtained from Alberta groundwater provide an excellent baseline against which potential future impact of deeper stray gases on shallow aquifers can be assessed. - Highlights: • Analysis of gas geochemical data from 186

Differentiation of wood-derived vanillin from synthetic vanillin in distillates using gas chromatography/combustion/isotope ratio mass spectrometry for δ13 C analysis.

Science.gov (United States)

van Leeuwen, Katryna A; Prenzler, Paul D; Ryan, Danielle; Paolini, Mauro; Camin, Federica

2018-02-28

Typical storage in oak barrels releases in distillates different degradation products such as vanillin, which play an important role in flavour and aroma. The addition of vanillin, as well as other aroma compounds, of different origin is prohibited by European laws. As vanillin samples from different sources have different δ 13 C values, the δ 13 C value could be used to determine whether the vanillin is authentic (lignin-derived), or if it has been added from another source (e.g. synthetic). The δ 13 C values for vanillin derived from different sources, including natural, synthetic and tannins, were measured by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS), after diethyl ether addition and/or ethanol dilution. A method for analysing vanillin in distillates after dichloromethane extraction was developed. Tests were undertaken to prove the reliability, reproducibility and accuracy of the method with standards and samples. Distillate samples were run to measure the δ 13 C values of vanillin and to compare them with values for other sources of vanillin. δ 13 C values were determined for: natural vanillin extracts (-21.0 to -19.3‰, 16 samples); vanillin ex-lignin (-28.2‰, 1 sample); and synthetic vanillin (-32.6 to -29.3‰, 7 samples). Seventeen tannin samples were found to have δ 13 C values of -29.5 to -26.7‰, which were significantly different (p distillates (-28.9 to -25.7‰) were mainly in the tannin range, although one spirit (-32.5‰) was found to contain synthetic vanillin. The results show that synthetic vanillin added to a distillate could be differentiated from vanillin derived from oak barrels by their respective δ 13 C values. The GC/C/IRMS method could be a useful tool in the determination of adulteration of distillates. Copyright © 2017 John Wiley & Sons, Ltd.

Process for hydrogen isotope exchange and concentration between liquid water and hydrogen gas and catalyst assembly therefor

International Nuclear Information System (INIS)

Stevens, W.H.

1975-01-01

A bithermal, catalytic, hydrogen isotope exchange process between liquid water and hydrogen gas to effect concentration of the deuterium isotope of hydrogen is described. Liquid water and hydrogen gas are contacted with one another and with at least one catalytically active metal selected from Group VIII of the Periodic Table; the catalyst body has a water repellent, gas and water vapor permeable, organic polymer or resin coating, preferably a fluorinated olefin polymer or silicone resin coating, so that the isotope exchange takes place by two simultaneously occurring, and closely coupled in space, steps and concentration is effected by operating two interconnected sections containing catalyst at different temperatures. (U.S.)

Reversed-phase liquid chromatography coupled on-line with capillary gas chromatography use of an anion-exchange membrane to remove an ion-pair reagent from the eluent.

NARCIS (Netherlands)

Brinkman, U.A.T.; Goosens, E.C.; de Jong, D.; de Jong, G.J.; Beerthuizen, I.M.

1995-01-01

In order to enable the coupling of reversed-phase liquid chromatography (RPLC) with capillary gas chromatography (GC), the performance of an anion-exchange micromembrane device has been studied to remove the ion-pair reagent methanesulphonic acid from an acetonitrile/water LC eluent. The regenerant

Chemical characterization and stable carbon isotopic composition of particulate Polycyclic Aromatic Hydrocarbons issued from combustion of 10 Mediterranean woods

Directory of Open Access Journals (Sweden)

A. Guillon

2013-03-01

Full Text Available The objectives of this study were to characterize polycyclic aromatic hydrocarbons from particulate matter emitted during wood combustion and to determine, for the first time, the isotopic signature of PAHs from nine wood species and Moroccan coal from the Mediterranean Basin. In order to differentiate sources of particulate-PAHs, molecular and isotopic measurements of PAHs were performed on the set of wood samples for a large panel of compounds. Molecular profiles and diagnostic ratios were measured by gas chromatography/mass spectrometry (GC/MS and molecular isotopic compositions (δ13C of particulate-PAHs were determined by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS. Wood species present similar molecular profiles with benz(aanthracene and chrysene as dominant PAHs, whereas levels of concentrations range from 1.8 to 11.4 mg g−1 OC (sum of PAHs. Diagnostic ratios are consistent with reference ratios from literature but are not sufficient to differentiate the species of woods. Concerning isotopic methodology, PAH molecular isotopic compositions are specific for each species and contrary to molecular fingerprints, significant variations of δ13C are observed for the panel of PAHs. This work allows differentiating wood combustion (with δ13CPAH = −28.7 to −26.6‰ from others origins of particulate matter (like vehicular exhaust using isotopic measurements but also confirms the necessity to investigate source characterisation at the emission in order to help and complete source assessment models. These first results on woodburnings will be useful for the isotopic approach to source tracking.

Nicotine, acetanilide and urea multi-level 2H-, 13C- and 15N-abundance reference materials for continuous-flow isotope ratio mass spectrometry.

Science.gov (United States)

Schimmelmann, Arndt; Albertino, Andrea; Sauer, Peter E; Qi, Haiping; Molinie, Roland; Mesnard, François

2009-11-01

Accurate determinations of stable isotope ratios require a calibration using at least two reference materials with different isotopic compositions to anchor the isotopic scale and compensate for differences in machine slope. Ideally, the delta values of these reference materials should bracket the isotopic range of samples with unknown delta values. While the practice of analyzing two isotopically distinct reference materials is common for water (VSMOW-SLAP) and carbonates (NBS 19 and L-SVEC), the lack of widely available organic reference materials with distinct isotopic composition has hindered the practice when analyzing organic materials by elemental analysis/isotope ratio mass spectrometry (EA-IRMS). At present only L-glutamic acids USGS40 and USGS41 satisfy these requirements for delta13C and delta15N, with the limitation that L-glutamic acid is not suitable for analysis by gas chromatography (GC). We describe the development and quality testing of (i) four nicotine laboratory reference materials for on-line (i.e. continuous flow) hydrogen reductive gas chromatography-isotope ratio mass-spectrometry (GC-IRMS), (ii) five nicotines for oxidative C, N gas chromatography-combustion-isotope ratio mass-spectrometry (GC-C-IRMS, or GC-IRMS), and (iii) also three acetanilide and three urea reference materials for on-line oxidative EA-IRMS for C and N. Isotopic off-line calibration against international stable isotope measurement standards at Indiana University adhered to the 'principle of identical treatment'. The new reference materials cover the following isotopic ranges: delta2H(nicotine) -162 to -45 per thousand, delta13C(nicotine) -30.05 to +7.72 per thousand, delta15N(nicotine) -6.03 to +33.62 per thousand; delta15N(acetanilide) +1.18 to +40.57 per thousand; delta13C(urea) -34.13 to +11.71 per thousand, delta15N(urea) +0.26 to +40.61 per thousand (recommended delta values refer to calibration with NBS 19, L-SVEC, IAEA-N-1, and IAEA-N-2). Nicotines fill a gap as

Lithium isotope effects in cation exchange chromatography of lithium lactate in water-dimethyl sulfoxide and water-acetone mixed solvent media

International Nuclear Information System (INIS)

Oi, Takao; Kondoh, Akiko; Ohno, Etsuko; Hosoe, Morikazu

1993-01-01

Lithium isotope separation by ion exchange displacement chromatography of lithium lactate in water-dimethyl sulfoxide (DMSO) and water-acetone mixed solvent media at 25 C was explored. In both the water-DMSO and water-acetone system, the single stage isotope separation factor (S) was a convex function of the mixing ratio of the solvents in the external solution phase; S had its maximum value of 1.00254 at water: DMSO=25:75 v/v and 1.00182 at water: acetone=75:25 v/v. Strong correlations of S with solvent partitions between the solution and the exchanger phases were found in both systems, which was qualitatively explainable by considering the lithium isotope distributions between the two phases based on the fundamental lithium isotope effects and the relative affinities of water, DMSO and acetone towards the lithium ion. (orig.)

Stable isotope measurements of atmospheric CO2

International Nuclear Information System (INIS)

White, J.W.C.; Ferretti, D.F.; Vaughn, B.H.; Francey, R.J.; Allison, C.E.

2002-01-01

The measurement of stable carbon isotope ratios of atmospheric carbon dioxide, δ 13 CO 2 are useful for partitioning surface-atmospheric fluxes into terrestrial and oceanic components. δC 18 OO also has potential for segregating photosynthetic and respiratory fluxes in terrestrial ecosystems. Here we describe in detail the techniques for making these measurements. The primary challenge for all of the techniques used to measure isotopes of atmospheric CO 2 is to achieve acceptable accuracy and precision and to maintain them over the decades needed to observe carbon cycle variability. The keys to success such an approach are diligent intercalibrations of laboratories from around the world, as well as the use of multiple techniques such as dual inlet and GC-IRMS and the intercomparison of such measurements. We focus here on two laboratories, the Stable Isotope Lab at the Institute for Arctic and Alpine Research (INSTAAR) at the University of Colorado is described and the Commonwealth Scientific and Industrial Research Organisation - Atmospheric Research (CSIRO). Different approaches exist at other laboratories (e.g. programs operated by Scripps Institution of Oceanography (SIO) and The Center for Atmospheric and Oceanic Studies, Toboku University (TU)) however these are not discussed here. Finally, we also discuss the recently developed Gas Chromatography - Isotope Ratio Mass Spectrometry (GC-IRMS) technique which holds significant promise for measuring ultra-small samples of gas with good precision. (author)

Principles and applications of a research-oriented gas chromatography-mass spectrometry data system

International Nuclear Information System (INIS)

Campana, J.E.; Risby, T.H.; Jurs, P.C.

1979-01-01

A research-oriented gas chromatography-mass spectrometry data system for a quadrupole mass spectrometer has been developed based on a centrally located departmental computer facility. An overview of the hardware and software system is presented, emphasizing the important aspects of on-line computer data acquisition and control and the design philosophy used in the development of the system. The application of the system is demonstrated by the g.c.-m.s. analysis of a mixture of four transition metal β-diketonates (Al, Cr, Rh, and Ru tris-1,1,1-trifluoro-pentane-2,4-dionate). This anaysis involved vacuum gas chromatography with a support-coated open tubular column and detection of the eluent by chemical ionization mass spectrometry. The results demonstrate the data system capabilities and indicate the utility of the combined methodologies. (Auth.)

Modeling of filling gas centrifuge cascade for nickel isotope separation by feed flow input to different stages

Directory of Open Access Journals (Sweden)

Orlov Alexey A.

2017-01-01

Full Text Available The article presents results of research filling gas centrifuge cascade by process gas fed into different stages. The modeling of filling cascade was done for nickel isotope separation. Analysis of the research results shows that nickel isotope concentrations of light and heavy fraction flows after filling cascade depend on feed stage number.

Comparison of an Electronic Nose Based on Ultrafast Gas Chromatography, Comprehensive Two-Dimensional Gas Chromatography, and Sensory Evaluation for an Analysis of Type of Whisky

Directory of Open Access Journals (Sweden)

Paulina Wiśniewska

2017-01-01

Full Text Available Whisky is one of the most popular alcoholic beverages. There are many types of whisky, for example, Scotch, Irish, and American whisky (called bourbon. The whisky market is highly diversified, and, because of this, it is important to have a method which would enable rapid quality evaluation and authentication of the type of whisky. The aim of this work was to compare 3 methods: an electronic nose based on the technology of ultrafast gas chromatography (Fast-GC, comprehensive two-dimensional gas chromatography (GC × GC, and sensory evaluation. The selected whisky brands included 6 blended whiskies from Scotland, 4 blended whiskies from Ireland, and 4 bourbons produced in the USA. For data analysis, peak heights of chromatograms were used. The panelists who took part in sensory evaluations included 4 women and 4 men. The obtained data were analyzed by 2 chemometric methods: partial least squares discriminant analysis (PLS-DA and discrimination function analysis (DFA. E-nose and GC × GC allowed for differentiation between whiskies by type. Sensory analysis did not allow for differentiation between whiskies by type, but it allowed giving consumer preferences.

Sm isotope composition and Sm/Eu ratio determination in an irradiated 153Eu sample by ion exchange chromatography-quadrupole inductively coupled plasma mass spectrometry combined with double spike isotope dilution technique

International Nuclear Information System (INIS)

Bourgeois, M.; Isnard, H.; Gourgiotis, A.; Stadelmann, G.; Gautier, C.; Mialle, S.; Nonell, A.; Chartier, F.

2011-01-01

Within the framework of the research undertaken by the French Atomic Energy Commission on transmutation of long-lived radionuclides, targets of highly enriched actinides and fission products were irradiated in the fast neutron reactor Phenix. Precise and accurate measurements of the isotopic and elemental composition of the enriched elements are therefore required. In order to obtain the uncertainties of several per mil and to reduce handling time and exposure to analyst on radioactive material, the on-line coupling of ion exchange chromatography with quadrupole inductively coupled plasma mass spectrometry has been associated with the technique of the double spike isotope dilution. We present in this paper the results obtained on an irradiated sample of Europium oxide powder (enriched at 99.13% in 153 Eu). After irradiation of around 5 mg of Eu 2 O 3 powder the theoretical calculations predict the formation of several micrograms of gadolinium and samarium isotopes. In relation to the very high activity of the sample after irradiation and the very low quantity of Sm formed, the on-line ion exchange chromatography separation of Gd, Sm and Eu before Sm isotope ratio measurements has been developed for the quantification of the 152 Sm/ 153 Eu ratio. These on-line measurements were associated with the double spike isotope dilution technique after calibration of a 147 Sm/ 151 Eu spike solution. The external reproducibility of Sm isotopic ratios was determined to be around 0.5% (2 σ) resulting in a final uncertainty on the 152 Sm/ 153 Eu ratio of around 1% (2 σ). These on-line measurements present therefore a robust and high-throughput alternative to the thermal-ionisation mass spectrometry technique used so far in combination with off-line chromatographic separation, particularly in nuclear applications where characterisation of high activity sample solutions is required. (authors)

Detection of radiation-induced hydrocarbons in Camembert irradiated before and after the maturing process-comparison of florisil column chromatography and on-line coupled liquid chromatography-gas chromatography

International Nuclear Information System (INIS)

Schulzki, G.; Spiegelberg, A.; Bögl, K.W.; Schreiber, G.A.

1995-01-01

The influence of the maturing process on the detection of radiation-induced volatile hydrocarbons in the fat of Camembert has been investigated. Two analytical methods for separation of the hydrocarbon fraction from the lipid were applied: Florisil column chromatography with subsequent gas chromatographic-mass spectrometric (GC-MS) determination as well as on-line coupled liquid chromatography-GC-MS. The maturing process had no influence on the detection of radiation-induced volatiles. Comparable results were achieved with both analytical methods. However, preference is given to the more effective on-line coupled LC-GC method

Galatic and solar cosmic ray - produced rare gas isotopes in lunar fines

International Nuclear Information System (INIS)

Bhushan, B.N.; Rao, M.N.; Venkatesan, T.R.

1979-01-01

Lunar fines 10084, 14163 and 14148 from Apollo 11 and 14 missions as well as 24087 from Soviet Luna 24 mission have been studied for elemental and isotopic composition of He, Ne, Ar, Kr and Xe using milligram amounts by step-wise heating techniques. From these studies, the isotopic composition of solar wind has been determined and it is found to be in good agreement with the results reported by other workers. The experimental procedure adopted for studying these samples is described in brief. The use of a gas glass spectrometer for detecting the subtle galatic and solar cosmic ray xenon is explained. Data on the concentration and isotopic composition of selected isotopes of Xe and Ne in lunar fines is presented. (K.B.)

Gas chromatography/sniffing port analysis of aroma compounds released under mouth conditions

NARCIS (Netherlands)

Ruth, van S.M.; Roozen, J.P.

2000-01-01

The release of aroma compounds from rehydrated French beans in an artificial mouth system and in the mouths of 12 assessors was studied by gas chromatography combined with flame ionisation detection and sniffing port detection. In an artificial mouth system, volatile compounds were isolated under

Comprehensive two-dimensional gas chromatography for the analysis of organohalogenated micro-contaminants

NARCIS (Netherlands)

Korytar, P.; Haglund, P.; Boer, de J.; Brinkman, U.A.Th.

2006-01-01

We explain the principles of comprehensive two-dimensional gas chromatography (GC × GC), and discuss key instrumental aspects - with emphasis on column combinations and mass spectrometric detection. As the main item of interest, we review the potential of GC × GC for the analysis of

Determination of petroleum fractions as contaminants in the waters by gas chromatography

International Nuclear Information System (INIS)

Kubinec, R.; Mracnova, R.; Kuran, P.; Ostrovsky, I.; Sojak, L.

1995-01-01

The method of micro-extraction of petroleum fractions from water and analysis using gas chromatography was developed. This method can be used for the analysis of gaseous oil and mineral oil in the water wit the detection limit 12 ppb and 18 ppb, respectively

Modelling non-steady-state isotope enrichment of leaf water in a gas-exchange cuvette environment.

Science.gov (United States)

Song, Xin; Simonin, Kevin A; Loucos, Karen E; Barbour, Margaret M

2015-12-01

The combined use of a gas-exchange system and laser-based isotope measurement is a tool of growing interest in plant ecophysiological studies, owing to its relevance for assessing isotopic variability in leaf water and/or transpiration under non-steady-state (NSS) conditions. However, the current Farquhar & Cernusak (F&C) NSS leaf water model, originally developed for open-field scenarios, is unsuited for use in a gas-exchange cuvette environment where isotope composition of water vapour (δv ) is intrinsically linked to that of transpiration (δE ). Here, we modified the F&C model to make it directly compatible with the δv -δE dynamic characteristic of a typical cuvette setting. The resultant new model suggests a role of 'net-flux' (rather than 'gross-flux' as suggested by the original F&C model)-based leaf water turnover rate in controlling the time constant (τ) for the approach to steady sate. The validity of the new model was subsequently confirmed in a cuvette experiment involving cotton leaves, for which we demonstrated close agreement between τ values predicted from the model and those measured from NSS variations in isotope enrichment of transpiration. Hence, we recommend that our new model be incorporated into future isotope studies involving a cuvette condition where the transpiration flux directly influences δv . There is an increasing popularity among plant ecophysiologists to use a gas-exchange system coupled to laser-based isotope measurement for investigating non-steady state (NSS) isotopic variability in leaf water (and/or transpiration); however, the current Farquhar & Cernusak (F&C) NSS leaf water model is unsuited for use in a gas-exchange cuvette environment due to its implicit assumption of isotope composition of water vapor (δv ) being constant and independent of that of transpiration (δE ). In the present study, we modified the F&C model to make it compatible with the dynamic relationship between δv and δE as is typically associated

Developments towards in-gas-jet laser spectroscopy studies of actinium isotopes at LISOL

International Nuclear Information System (INIS)

Raeder, S.; Bastin, B.; Block, M.; Creemers, P.; Delahaye, P.; Ferrer, R.; Fléchard, X.; Franchoo, S.; Ghys, L.; Gaffney, L.P.; Granados, C.; Heinke, R.; Hijazi, L.

2016-01-01

To study exotic nuclides at the borders of stability with laser ionization and spectroscopy techniques, highest efficiencies in combination with a high spectral resolution are required. These usually opposing requirements are reconciled by applying the in-gas-laser ionization and spectroscopy (IGLIS) technique in the supersonic gas jet produced by a de Laval nozzle installed at the exit of the stopping gas cell. Carrying out laser ionization in the low-temperature and low density supersonic gas jet eliminates pressure broadening, which will significantly improve the spectral resolution. This article presents the required modifications at the Leuven Isotope Separator On-Line (LISOL) facility that are needed for the first on-line studies of in-gas-jet laser spectroscopy. Different geometries for the gas outlet and extraction ion guides have been tested for their performance regarding the acceptance of laser ionized species as well as for their differential pumping capacities. The specifications and performance of the temporarily installed high repetition rate laser system, including a narrow bandwidth injection-locked Ti:sapphire laser, are discussed and first preliminary results on neutron-deficient actinium isotopes are presented indicating the high capability of this novel technique.

Developments towards in-gas-jet laser spectroscopy studies of actinium isotopes at LISOL

Energy Technology Data Exchange (ETDEWEB)

Raeder, S., E-mail: s.raeder@gsi.de [KU Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Helmholtz-Institut Mainz, 55128 Mainz (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany); Bastin, B. [GANIL, CEA/DSM-CNRS/IN2P3, B.P. 55027, 14076 Caen (France); Block, M. [Helmholtz-Institut Mainz, 55128 Mainz (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany); Institut für Kernchemie, Johannes Gutenberg Universität, 55128 Mainz (Germany); Creemers, P. [KU Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Delahaye, P. [GANIL, CEA/DSM-CNRS/IN2P3, B.P. 55027, 14076 Caen (France); Ferrer, R. [KU Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Fléchard, X. [LPC Caen, ENSICAEN, Université de Caen, CNRS/IN2P3, Caen (France); Franchoo, S. [Institute de Physique Nucléaire (IPN) d’Orsay, 91406 Orsay, Cedex (France); Ghys, L. [KU Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200D, B-3001 Leuven (Belgium); SCK-CEN, Belgian Nuclear Research Center, Boeretang 200, 2400 Mol (Belgium); Gaffney, L.P.; Granados, C. [KU Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Heinke, R. [Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz (Germany); Hijazi, L. [GANIL, CEA/DSM-CNRS/IN2P3, B.P. 55027, 14076 Caen (France); and others

2016-06-01

To study exotic nuclides at the borders of stability with laser ionization and spectroscopy techniques, highest efficiencies in combination with a high spectral resolution are required. These usually opposing requirements are reconciled by applying the in-gas-laser ionization and spectroscopy (IGLIS) technique in the supersonic gas jet produced by a de Laval nozzle installed at the exit of the stopping gas cell. Carrying out laser ionization in the low-temperature and low density supersonic gas jet eliminates pressure broadening, which will significantly improve the spectral resolution. This article presents the required modifications at the Leuven Isotope Separator On-Line (LISOL) facility that are needed for the first on-line studies of in-gas-jet laser spectroscopy. Different geometries for the gas outlet and extraction ion guides have been tested for their performance regarding the acceptance of laser ionized species as well as for their differential pumping capacities. The specifications and performance of the temporarily installed high repetition rate laser system, including a narrow bandwidth injection-locked Ti:sapphire laser, are discussed and first preliminary results on neutron-deficient actinium isotopes are presented indicating the high capability of this novel technique.

Isotope-dilution gas chromatography-mass spectrometry coupled with injection-port butylation for the determination of 4-t-octylphenol, 4-nonylphenols and bisphenol A in human urine.

Science.gov (United States)

Chung, Shuang-Hung; Ding, Wang-Hsien

2018-02-05

An analytical method that utilizes isotope-dilution gas chromatography-mass spectrometry (ID-GC-MS) coupled with injection-port butylation was developed. The method was validated, and confirmed to be able to determine the presence of three commonly detected endocrine-disrupting chemicals (EDCs: 4-tert-octylphenol (4-t-OP), 4-nonylphenols (4-NPs) and bisphenol A (BPA)) in human urine with high precision and accuracy. After sample preparation by solid-phase extraction, the extract was introduced into GC-MS via injection-port butylation. The butylated target analytes were identified and quantified by using ion-trap mass spectrometry operating in the selected-ion-storage mode, and employing the measurement of peak area ratios of the butylated target analytes and labeled-analogues in the samples and calibration standards. The labeled-analogues were also used to correct the variations associated with the analysis and matrix effect. The limits of quantitation (LOQs) ranged from 0.1 to 0.3ng/mL. High precisions for both intra- and inter-day analysis ranged from 1 to 6%, and excellent accuracy (mean recovery) ranged from 92 to 105% on two concentration levels. In human urine, the total concentrations of three selected EDCs varied from 1.28 to 7.14ng/mL. 4-NPs were detected within all collected samples. The developed method allows accurate analysis of trace-level of EDCs in urine, and these target EDCs could act as useful biomarkers to assess exposure in biomonitoring studies and programs. Copyright © 2017 Elsevier B.V. All rights reserved.

Learning from soil gas change and isotopic signatures during 2012 Emilia seismic sequence.

Science.gov (United States)

Sciarra, Alessandra; Cantucci, Barbara; Coltorti, Massimo

2017-10-27

Soil surveys were performed in Medolla (Italy), a peculiar area characterized by spotty high soil temperature, gas vent, and lack of vegetation, to determine the migration mechanisms and spatial behavior of gas species. Hereby we present soil gas measurements and their isotopic ratios measured between 2008 and 2015, including the 2012 Emilia-Romagna seismic sequence. We found that soil gas concentrations markedly changed during the main shocks of May 20 and 29, 2012 (Mw 6.1 and 6.0, respectively), highlighting the presence of a buried fault intersecting the gas vents. We suggest that crustal dilation associated with seismic activity favored the uprising of geogas towards the surface. Changes in the isotopic signature highlight the contribution of two distinct sources, one deeper, thermogenic and another superficial related to organic-rich layer, whose relative contribution varied before, during and after the earthquake. We suppose an increase of microbial component likely due to the ground shaking of shallower layers linked to seismic sequence, which masks the thermogenic contribution. Although the changes we detect are specific for an alluvial plain, we deduce that analogous processes may be active elsewhere, and that soil gas geochemistry represents an useful tool to discriminate the gas migration related to seismic activity.

Online Simultaneous Hydrogen/Deuterium Exchange of Multitarget Gas-Phase Molecules by Electrospray Ionization Mass Spectrometry Coupled with Gas Chromatography.

Science.gov (United States)

Jeong, Eun Sook; Cha, Eunju; Cha, Sangwon; Kim, Sunghwan; Oh, Han Bin; Kwon, Oh-Seung; Lee, Jaeick

2017-11-21

In this study, a hydrogen/deuterium (H/D) exchange method using gas chromatography-electrospray ionization/mass spectrometry (GC-ESI/MS) was first investigated as a novel tool for online H/D exchange of multitarget analytes. The GC and ESI source were combined with a homemade heated column transfer line. GC-ESI/MS-based H/D exchange occurs in an atmospheric pressure ion source as a result of reacting the gas-phase analyte eluted from GC with charged droplets of deuterium oxide infused as the ESI spray solvent. The consumption of the deuterated solvent at a flow rate of 2 μL min -1 was more economical than that in online H/D exchange methods reported to date. In-ESI-source H/D exchange by GC-ESI/MS was applied to 11 stimulants with secondary amino or hydroxyl groups. After H/D exchange, the spectra of the stimulants showed unexchanged, partially exchanged, and fully exchanged ions showing various degrees of exchange. The relative abundances corrected for naturally occurring isotopes of the fully exchanged ions of stimulants, except for etamivan, were in the range 24.3-85.5%. Methylephedrine and cyclazodone showed low H/D exchange efficiency under acidic, neutral, and basic spray solvent conditions and nonexchange for etamivan with an acidic phenolic OH group. The in-ESI-source H/D exchange efficiency by GC-ESI/MS was sufficient to determine the number of hydrogen by elucidation of fragmentation from the spectrum. Therefore, this online H/D exchange technique using GC-ESI/MS has potential as an alternative method for simultaneous H/D exchange of multitarget analytes.

The Origin of Noble Gas Isotopic Heterogeneity in Icelandic Basalts

Science.gov (United States)

Dixon, E. T.; Honda, M.; McDougall, I.

2001-01-01

Two models for generation of heterogeneous He, Ne and Ar isotopic ratios in Icelandic basalts are evaluated using a mixing model and the observed noble gas elemental ratios in Icelandic basalts,Ocean island Basalt (OIBs) and Mid-Ocean Ridge Basalt (MORBs). Additional information is contained in the original extended abstract.

Odour-active compounds of Citrus deliciosa Tenore var. Caí essential oils detected by gas chromatography-mass spectrometry and gas chromatography-olfactometry

Directory of Open Access Journals (Sweden)

Manuel A. Minteguiaga

2017-11-01

Full Text Available Context: Mandarins are a complex taxonomic group including different species, cultivars and hybrids growing around the world being fruits greatly appreciated by the consumers. Citrus deliciosa Tenore var. Caí originates from Rio Grande do Sul State (Brazil and the fruit is characterised by its pleasant properties, especially its aroma. Aims: To evaluate the C. deliciosa cold-pressed essential oils, classified as “green”, “yellow” and “red” according to fruit maturity, and the one produced by distillation by gas chromatography-mass spectrometry (GC-MS and gas chromatography-olfactometry (GC-O. Methods: The essential oils aromatic quality was evaluated by GC-O through a panel of trained judges. The identification of the volatile compounds was performed by GC-MS and their quantification by GC-FID. Results: The chemical composition of the three types of cold-pressed essential oils was very similar. However, the distilled oil presented a higher concentration of oxygenated monoterpenes (mainly α-terpineol, 4-terpineol and sabinene hydrates. Herbaceous and floral aromatic notes were able to describe the “green” oil, while for the distilled oil wood and unpleasant notes were perceived. Conclusions: The cold-pressed oils did not show nor chemical, or aromatic differences, by the fruit maturity. The distilled oil was characterized by aromatic nuances making the oil less appreciated (inferior quality than the cold-pressed oil. Probably as consequence of artifacts formation during the distillation process.

Application of gas chromatography to the investigations on polypropylene radiolysis

International Nuclear Information System (INIS)

Zagorski, Z.P.; Gluszewski, W.

2006-01-01

Refinement of the gas chromatography (GC) instrumental approach permitted not only improvement of investigation in basic research, but also development of a new kind of polypropylene blends, more suitable for the production of medical devices and radiation sterilization. It has been shown, that using the GC method not only methane and carbon dioxide can be measured, but also the consumption of oxygen which reacts with free radicals on the polypropylene chain

Sample collection and preparation of biofluids and extracts for gas chromatography-mass spectrometry.

Science.gov (United States)

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

2015-01-01

To maximize the utility of gas chromatography-mass spectrometry (GC-MS) in metabonomics research, all stages of the experimental design should be standardized, including sample collection, storage, preparation, and sample separation. Moreover, the prerequisite for any GC-MS analysis is that a compound must be volatile and thermally stable if it is to be analyzed using this technique. Since many metabolites are nonvolatile and polar in nature, they are not readily amenable to analysis by GC-MS and require initial chemical derivatization of the polar functional groups in order to reduce the polarity and to increase the thermal stability and volatility of the analytes. In this chapter, an overview is presented of the optimum approach to sample collection, storage, and preparation for gas chromatography-mass spectrometry-based metabonomics with particular focus on urine samples as example of biofluids.

Fuel spill identification by gas chromatography -- genetic algorithms/pattern recognition techniques

International Nuclear Information System (INIS)

Lavine, B.K.; Moores, A.J.; Faruque, A.

1998-01-01

Gas chromatography and pattern recognition methods were used to develop a potential method for typing jet fuels so a spill sample in the environment can be traced to its source. The test data consisted of 256 gas chromatograms of neat jet fuels. 31 fuels that have undergone weathering in a subsurface environment were correctly identified by type using discriminants developed from the gas chromatograms of the neat jet fuels. Coalescing poorly resolved peaks, which occurred during preprocessing, diminished the resolution and hence information content of the GC profiles. Nevertheless a genetic algorithm was able to extract enough information from these profiles to correctly classify the chromatograms of weathered fuels. This suggests that cheaper and simpler GC instruments ca be used to type jet fuels

Quantitative Analysis of Bioactive Compounds from Aromatic Plants by Means of Dynamic Headspace Extraction and Multiple Headspace Extraction-Gas Chromatography-Mass Spectrometry

NARCIS (Netherlands)

Omar, Jone; Olivares, Maitane; Alonso, Ibone; Vallejo, Asier; Aizpurua-Olaizola, Oier; Etxebarria, Nestor

2016-01-01

Seven monoterpenes in 4 aromatic plants (sage, cardamom, lavender, and rosemary) were quantified in liquid extracts and directly in solid samples by means of dynamic headspace-gas chromatography-mass spectrometry (DHS-GC-MS) and multiple headspace extraction-gas chromatography-mass spectrometry

Analysis of carbon stable isotope to determine the origin and migration of gaseous hydrocarbon in the Brazilian sedimentary basins

International Nuclear Information System (INIS)

Takaki, T.; Rodrigues, R.

1986-01-01

The carbon isotopic composition of natural gases to determine the origin and gaseous hydrocarbon migration of Brazilian sedimentar basins is analysed. The carbon isotopic ratio of methane from natural gases depends on the process of gas formation and stage of organic matter maturation. In the geochemical surface exploration the biogenic gases are differentiated from thermogenic gases, because the last one is isotopically heavier. As the isotopic composition of methane has not changed during migration, the migrated gases from deeper and more mature source rocks are identified by its relative 13 C enrichment. The methane was separated from chromatography and and the isotopic analysis was done with mass spectrometer. (M.C.K.) [pt

Studying Intermolecular Forces with a Dual Gas Chromatography and Boiling Point Investigation

Science.gov (United States)

Cunningham, William Patrick; Xia, Ian; Wickline, Kaitlyn; Huitron, Eric Ivan Garcia; Heo, Jun

2018-01-01

A procedure for the study of structural differences and intermolecular attraction between ethanol and 1-butanol based in laboratory work is described. This study provides comparisons of data retrieved from both a determination of boiling point and gas chromatography traces for the mixture. The methodology reported here should provide instructors…

Pseudo-absolute quantitative analysis using gas chromatography – Vacuum ultraviolet spectroscopy – A tutorial

Energy Technology Data Exchange (ETDEWEB)

Bai, Ling [Department of Chemistry & Biochemistry, The University of Texas at Arlington, Arlington, TX (United States); Smuts, Jonathan; Walsh, Phillip [VUV Analytics, Inc., Cedar Park, TX (United States); Qiu, Changling [Department of Chemistry & Biochemistry, The University of Texas at Arlington, Arlington, TX (United States); McNair, Harold M. [Department of Chemistry, Virginia Tech, Blacksburg, VA (United States); Schug, Kevin A., E-mail: kschug@uta.edu [Department of Chemistry & Biochemistry, The University of Texas at Arlington, Arlington, TX (United States)

2017-02-08

The vacuum ultraviolet detector (VUV) is a new non-destructive mass sensitive detector for gas chromatography that continuously and rapidly collects full wavelength range absorption between 120 and 240 nm. In addition to conventional methods of quantification (internal and external standard), gas chromatography - vacuum ultraviolet spectroscopy has the potential for pseudo-absolute quantification of analytes based on pre-recorded cross sections (well-defined absorptivity across the 120–240 nm wavelength range recorded by the detector) without the need for traditional calibration. The pseudo-absolute method was used in this research to experimentally evaluate the sources of sample loss and gain associated with sample introduction into a typical gas chromatograph. Standard samples of benzene and natural gas were used to assess precision and accuracy for the analysis of liquid and gaseous samples, respectively, based on the amount of analyte loaded on-column. Results indicate that injection volume, split ratio, and sampling times for splitless analysis can all contribute to inaccurate, yet precise sample introduction. For instance, an autosampler can very reproducibly inject a designated volume, but there are significant systematic errors (here, a consistently larger volume than that designated) in the actual volume introduced. The pseudo-absolute quantification capability of the vacuum ultraviolet detector provides a new means for carrying out system performance checks and potentially for solving challenging quantitative analytical problems. For practical purposes, an internal standardized approach to normalize systematic errors can be used to perform quantitative analysis with the pseudo-absolute method. - Highlights: • Gas chromatography diagnostics and quantification using VUV detector. • Absorption cross-sections for molecules enable pseudo-absolute quantitation. • Injection diagnostics reveal systematic errors in hardware settings. • Internal

Pseudo-absolute quantitative analysis using gas chromatography – Vacuum ultraviolet spectroscopy – A tutorial

International Nuclear Information System (INIS)

Bai, Ling; Smuts, Jonathan; Walsh, Phillip; Qiu, Changling; McNair, Harold M.; Schug, Kevin A.

2017-01-01

The vacuum ultraviolet detector (VUV) is a new non-destructive mass sensitive detector for gas chromatography that continuously and rapidly collects full wavelength range absorption between 120 and 240 nm. In addition to conventional methods of quantification (internal and external standard), gas chromatography - vacuum ultraviolet spectroscopy has the potential for pseudo-absolute quantification of analytes based on pre-recorded cross sections (well-defined absorptivity across the 120–240 nm wavelength range recorded by the detector) without the need for traditional calibration. The pseudo-absolute method was used in this research to experimentally evaluate the sources of sample loss and gain associated with sample introduction into a typical gas chromatograph. Standard samples of benzene and natural gas were used to assess precision and accuracy for the analysis of liquid and gaseous samples, respectively, based on the amount of analyte loaded on-column. Results indicate that injection volume, split ratio, and sampling times for splitless analysis can all contribute to inaccurate, yet precise sample introduction. For instance, an autosampler can very reproducibly inject a designated volume, but there are significant systematic errors (here, a consistently larger volume than that designated) in the actual volume introduced. The pseudo-absolute quantification capability of the vacuum ultraviolet detector provides a new means for carrying out system performance checks and potentially for solving challenging quantitative analytical problems. For practical purposes, an internal standardized approach to normalize systematic errors can be used to perform quantitative analysis with the pseudo-absolute method. - Highlights: • Gas chromatography diagnostics and quantification using VUV detector. • Absorption cross-sections for molecules enable pseudo-absolute quantitation. • Injection diagnostics reveal systematic errors in hardware settings. • Internal

Comprehensive two-dimensional gas chromatography for biogas and biomethane analysis.

Science.gov (United States)

Hilaire, F; Basset, E; Bayard, R; Gallardo, M; Thiebaut, D; Vial, J

2017-11-17

The gas industry is going to be revolutionized by being able to generate bioenergy from biomass. The production of biomethane - a green substitute of natural gas - is growing in Europe and the United-States of America. Biomethane can be injected into the gas grid or used as fuel for vehicles after compression. Due to various biomass inputs (e.g. agricultural wastes, sludges from sewage treatment plants, etc.), production processes (e.g. anaerobic digestion, municipal solid waste (MSW) landfills), seasonal effects and purification processes (e.g. gas scrubbers, pressure swing adsorption, membranes for biogas upgrading), the composition and quality of biogas and biomethane produced is difficult to assess. All previous publications dealing with biogas analysis reported that hundreds of chemicals from ten chemical families do exist in trace amounts in biogas. However, to the best of our knowledge, no study reported a detailed analysis or the implementation of comprehensive two-dimensional gas chromatography (GC×GC) for biogas matrices. This is the reason why the benefit of implementing two-dimensional gas chromatography for the characterization of biogas and biomethane samples was evaluated. In a first step, a standard mixture of 89 compounds belonging to 10 chemical families, representative of those likely to be found, was used to optimize the analytical method. A set consisting of a non-polar and a polar columns, respectively in the first and the second dimension, was used with a modulation period of six seconds. Applied to ten samples of raw biogas, treated biogas and biomethane collected on 4 industrial sites (two MSW landfills, one anaerobic digester on a wastewater treatment plant and one agricultural biogas plant), this analytical method provided a "fingerprint" of the gases composition at the molecular level in all biogas and biomethane samples. Estimated limits of detection (far below the μgNm -3 ) coupled with the resolution of GC×GC allowed the comparison

Investigation of Pinus mugo essential oil oxygenated fraction by combined use of gas chromatography and dry column chromatography.

Science.gov (United States)

A, M B; Coran, S A; Giannellini, V; Vincieri, F F; Moneti, G

1981-09-01

The oxygenated compounds of Pinus mugo Turra essential oil were investigated by a combination of GC and dry column chromatography (DCC) coordinated by GC data processing. The collected data resulted in a bar graph ("normalized" gas chromatogram) giving the RRT's and relative amounts of 68 components; 38 of them were identified by MS and IR. The described procedure may be used for essential oil analysis in general.

Rate of Isotope Exchange Reaction Between Tritiated Water in a Gas Phase and Water on the Surface of Piping Materials

International Nuclear Information System (INIS)

Nakashio, Nobuyuki; Yamaguchi, Junya; Kobayashi, Ryusuke; Nishikawa, Masabumi

2001-01-01

The system effect of tritium arises from the interaction of tritium in the gas phase with water on the surface of piping materials. It has been reported that the system effect can be quantified by applying the serial reactor model to the piping system and that adsorption and isotope exchange reactions play the main roles in the trapping of tritium. The isotope exchange reaction that occurs when the chemical form of tritium in the gas phase is in the molecular form, i.e., HT or T 2 , has been named isotope exchange reaction 1, and that which occurs when tritium in the gas phase is in water form, i.e., HTO or T 2 O, has been named isotope exchange reaction 2.The rate of isotope exchange reaction 2 is experimentally quantified, and the rate is observed to be about one-third of the rate of adsorption. The trapping and release behavior of tritium from the piping surface due to isotope exchange reaction 2 is also discussed. It is certified that swamping of water vapor to process gas is effective to release tritium from the surface contaminated with tritium

Quantitative measurement of carbon isotopic composition in CO2 gas reservoir by Micro-Laser Raman spectroscopy

Science.gov (United States)

Li, Jiajia; Li, Rongxi; Zhao, Bangsheng; Guo, Hui; Zhang, Shuan; Cheng, Jinghua; Wu, Xiaoli

2018-04-01

The use of Micro-Laser Raman spectroscopy technology for quantitatively determining gas carbon isotope composition is presented. In this study, 12CO2 and 13CO2 were mixed with N2 at various molar fraction ratios to obtain Raman quantification factors (F12CO2 and F13CO2), which provide a theoretical basis for calculating the δ13C value. And the corresponding values were 0.523 (0 Laser Raman analysis were carried out on natural CO2 gas from Shengli Oil-field at room temperature under different pressures. The δ13C values obtained by Micro-Laser Raman spectroscopy technology and Isotope Ratio Mass Spectrometry (IRMS) technology are in good agreement with each other, and the relative errors range of δ13C values is 1.232%-6.964%. This research provides a fundamental analysis tool for determining gas carbon isotope composition (δ13C values) quantitatively by using Micro-Laser Raman spectroscopy. Experiment of results demonstrates that this method has the potential for obtaining δ13C values in natural CO2 gas reservoirs.

Identification and measurement of chlorinated organic pesticides in water by electron-capture gas chromatography

Science.gov (United States)

Lamar, William L.; Goerlitz, Donald F.; Law, LeRoy M.

1965-01-01

Pesticides, in minute quantities, may affect the regimen of streams, and because they may concentrate in sediments, aquatic organisms, and edible aquatic foods, their detection and their measurement in the parts-per-trillion range are considered essential. In 1964 the U.S. Geological Survey at Menlo Park, Calif., began research on methods for monitoring pesticides in water. Two systems were selected--electron-capture gas chromatography and microcoulometric-titration gas chromatography. Studies on these systems are now in progress. This report provides current information on the development and application of an electron-capture gas chromatographic procedure. This method is a convenient and extremely sensitive procedure for the detection and measurement of organic pesticides having high electron affinities, notably the chlorinated organic pesticides. The electron-affinity detector is extremely sensitive to these substances but it is not as sensitive to many other compounds. By this method, the chlorinated organic pesticide may be determined on a sample of convenient size in concentrations as low as the parts-per-trillion range. To insure greater accuracy in the identifications, the pesticides reported were separated and identified by their retention times on two different types of gas chromatographic columns.

Quantitative Analysis of Ingenol in Euphorbia species via Validated Isotope Dilution Ultra-high Performance Liquid Chromatography Tandem Mass Spectrometry

Czech Academy of Sciences Publication Activity Database

Béres, T.; Dragull, K.; Pospíšil, Jiří; Tarkowská, Danuše; Dančák, M.; Bíba, Ondřej; Tarkowski, P.; Doležal, K.; Strnad, Miroslav

2018-01-01

Roč. 29, č. 1 (2018), s. 23-29 ISSN 0958-0344 R&D Projects: GA ČR GA17-14007S; GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : Euphorbia genus * ingenol * isotope-dilution method * mass spectrometry * ultra-high performance liquid chromatography Subject RIV: FD - Oncology ; Hematology OBOR OECD: Analytical chemistry Impact factor: 2.292, year: 2016

Determination of daminozide residues in apples using gas chromatography with nitrogen-phosphorus detection

NARCIS (Netherlands)

Brinkman, J.H.W.; Dijk, A.G. van; Wagenaar, R.; Quirijns, J.K.

1996-01-01

A method was developed for the determination of daminozide in apples using gas chromatography (GC) with nitrogen-phosphorus detection (NPD). Daminozide is hydrolysed to 1,1-dimethylhydrazine (UDMH) by alkaline digestion. The UDMH generated is distilled from the apple matrix, derivatized with

Determining the Levels of Volatile Organic Pollutants in Urban Air Using a Gas Chromatography-Mass Spectrometry Method

Science.gov (United States)

Nicoara, Simona; Tonidandel, Loris; Traldi, Pietro; Watson, Jonathan; Morgan, Geraint; Popa, Ovidiu

2009-01-01

The paper presents the application of a method based on coupled gas chromatography-mass spectrometry, using an isotopically labelled internal standard for the quantitative analysis of benzene (B), toluene (T), ethyl benzene (E), and o-, m-, p-xylenes (X). Their atmospheric concentrations were determined based on short-term sampling, in different sites of Cluj-Napoca, a highly populated urban centre in N-W Romania, with numerous and diversified road vehicles with internal combustion engines. The method is relatively inexpensive and simple and shows good precision and linearity in the ranges of 7–60 μg/m3 (B), 13–90 μg/m3 (T), 7–50 μg/m3 (E), 10–70 μg/m3 (X-m,p), and 20–130 μg/m3 (X-o). The limits of quantitation/detection of the method LOQ/LOD are of 10/5 μg/m3 (Xo), 5/3 μg/m3 (B, E, X-m,p), and of 3/1 μg/m3 (T), respectively. PMID:20168976

Determining the Levels of Volatile Organic Pollutants in Urban Air Using a Gas Chromatography-Mass Spectrometry Method

Directory of Open Access Journals (Sweden)

Simona Nicoara

2009-01-01

Full Text Available The paper presents the application of a method based on coupled gas chromatography-mass spectrometry, using an isotopically labelled internal standard for the quantitative analysis of benzene (B, toluene (T, ethyl benzene (E, and o-, m-, p-xylenes (X. Their atmospheric concentrations were determined based on short-term sampling, in different sites of Cluj-Napoca, a highly populated urban centre in N-W Romania, with numerous and diversified road vehicles with internal combustion engines. The method is relatively inexpensive and simple and shows good precision and linearity in the ranges of 7–60 μg/m3 (B, 13–90 μg/m3 (T, 7–50 μg/m3 (E, 10–70 μg/m3 (X-m,p, and 20–130 μg/m3 (X-o. The limits of quantitation/detection of the method LOQ/LOD are of 10/5 μg/m3 (Xo, 5/3 μg/m3 (B, E, X-m,p, and of 3/1 μg/m3 (T, respectively.

The effect of a micro bubble dispersed gas phase on hydrogen isotope transport in liquid metals under nuclear irradiation

Energy Technology Data Exchange (ETDEWEB)

Fradera, J., E-mail: jfradera@ubu.es; Cuesta-López, S., E-mail: scuesta@ubu.es

2013-12-15

The present work intend to be a first step towards the understanding and quantification of the hydrogen isotope complex phenomena in liquid metals for nuclear technology. Liquid metals under nuclear irradiation in, e.g., breeding blankets of a nuclear fusion reactor would generate tritium which is to be extracted and recirculated as fuel. At the same time that tritium is bred, helium is also generated and may precipitate in the form of nano bubbles. Other liquid metal systems of a nuclear reactor involve hydrogen isotope absorption processes, e.g., tritium extraction system. Hence, hydrogen isotope absorption into gas bubbles modelling and control may have a capital importance regarding design, operation and safety. Here general models for hydrogen isotopes transport in liquid metal and absorption into gas phase, that do not depend on the mass transfer limiting regime, are exposed and implemented in OpenFOAM® CFD tool for 0D–3D simulations. Results for a 0D case show the impact of a He dispersed phase of nano bubbles on hydrogen isotopes inventory at different temperatures as well as the inventory evolution during a He nucleation event. In addition, 1D and 2D axisymmetric cases are exposed showing the effect of a He dispersed gas phase on hydrogen isotope permeation through a lithium lead eutectic alloy and the effect of vortical structures on hydrogen isotope transport at a backward facing step. Exposed results give a valuable insight on current nuclear technology regarding the importance of controlling hydrogen isotope transport and its interactions with nucleation event through gas absorption processes.

Numerical simulation of bellows effect on flow and separation of uranium isotopes in a supercritical gas centrifuge

International Nuclear Information System (INIS)

Borisevich, V.D.; Morozov, O.E.; Godisov, O.N.

2000-01-01

Numerical solving of the Navier-Stokes and convection-diffusion equations by the finite difference technique has been applied to study the influence of bellows on the flow and separation of uranium isotopes in a single supercritical gas centrifuge. Dependence of the separative power of a gas centrifuge on geometric parameters and position of a bellows on a rotor wall as well as the effect of scoop drag and feed flow on isotope separation in a gas centrifuge with a bellows have been obtained in computing experiments. It was demonstrated that increase of the separative power with increase of the gas centrifuge length is less considerable than predicted by the Dirac's law

[Determination of acetochlor and oxyfluorfen by capillary gas chromatography].

Science.gov (United States)

Xiang, Wen-Sheng; Wang, Xiang-Jing; Wang, Jing; Wang, Qing

2002-09-01

A method is described for the determination of acetochlor and oxyfluorfen by capillary gas chromatography with FID and an SE-30 capillary column (60 m x 0.53 mm i. d., 1.5 microm), using dibutyl phthalate as the internal standard. The standard deviations for acetochlor and oxyfluorfen concentration(mass fraction) were 0.44% and 0.47% respectively. The relative standard deviations for acetochlor and oxyfluorfen were 0.79% and 0.88% and the average recoveries for acetochlor and oxyfluorfen were 99.3% and 101.1% respectively. The method is simple, rapid and accurate.

Gas chromatography of alkylphosphonic and dialkyl phosphinic acids

International Nuclear Information System (INIS)

Gasco Sanchez, L.; Barrera Pinero, R.; Ramirez Caceres, A.; Martin Munoz, M.

1978-01-01

After carrying out an optimization study on the separation conditions for the TMSr- derivatives, of the hexyl-, cyclohexyl-, heptyl-, and octyl-phosphonic acids; dihexyl dicyclohexyl-, heptyl-, and octyl-phosphinic acids, and dioctyl phosphine oxide, their retention indices (I) at two temperatures and on the OV-1 and OV-17 stationary phase were determined. Correlations between I and molecular structure were established. Calibration factors of these compounds in the flame ionization detector were studied, and the results analyzed taking into account the variables affecting the quantitative results, These results were unbiased but they had a lower precision than that usually achievable in gas chromatography. (Author) 24 refs

State-of-the art of selective detection and identification of I-, Br-, Cl-, and F-containing compounds in gas chromatography and liquid chromatography.

Science.gov (United States)

Brede, Cato; Pedersen-Bjergaard, Stig

2004-09-24

This review article presents an overview of halogen-specific detection in gas chromatography (GC) and liquid chromatography (LC). Attention is primarily focused on the use of plasma emission spectroscopy and plasma mass spectrometry as detectors, but other halogen-selective detection principles are also mentioned. Different instrumental configurations are discussed both with respect to technical set-up and performance, the principal reasons for halogen-selective detection are highlighted, and recent applications are reviewed from areas such as environmental chemistry, petroleum characterization, and drug analysis.

Direct solid-phase microextraction combined with gas and liquid chromatography for the determination of lidocaine in human urine

NARCIS (Netherlands)

Koster, E.H M; Hofman, N.S K; de Jong, G.J.

Solid-phase microextraction (SPME) has been combined with gas chromatography (GC) and liquid chromatography (LC) for the determination of lidocaine in human urine. A polydimethylsiloxane (PDMS) coated fibre was directly immersed into buffered urine. Extraction conditions such as time, pH, ionic

Intercomparison of the measurements of oxalic acid in aerosols by gas chromatography and ion chromatography

Science.gov (United States)

Kawamura, Kimitaka; Barrie, Leonard A.; Toom-Sauntry, Desiree

2010-12-01

Oxalate, the anion of oxalic acid, is one of the most abundant measurable organic species in atmospheric aerosols. Traditionally, this bifunctional species has been measured by gas chromatography (GC) after derivatization to butyl ester and by ion chromatography (IC) without derivatization. However, there are few published comparisons of the two techniques. Here, we report the results of an intercomparison study for the measurement of oxalic acid in Arctic aerosols (oxalic acid by GC ranged from 6.5-59.1 ng m -3 (av. 26.0 ng m -3, median 26.2 ng m -3) whereas those by IC ranged from 6.6-52.1 ng m -3 (av. 26.6 ng m -3, median 25.4 ng m -3). They showed a good correlation ( r = 0.84) with a slope of 0.96. Thus, observations of oxalate obtained by GC employing dibutyl esters are almost equal to those by IC. Because the accuracy of oxalic acid by GC method largely depends on the method used, it is important to strictly examine the recovery in each study.

A fast, comprehensive screening method for doping agents in urine by gas chromatography-triple quadrupole mass spectrometry.

Science.gov (United States)

Van Eenoo, Peter; Van Gansbeke, Wim; De Brabanter, Nik; Deventer, Koen; Delbeke, Frans T

2011-05-27

The use of performance enhancing drugs in sports is prohibited. For the detection of misuse of such substances gas chromatography or liquid chromatography coupled to mass spectrometry are the most frequently used detection techniques. In this work the development and validation of a fast gas chromatography tandem mass spectrometric method for the detection of a wide range of doping agents is described. The method can determine 13 endogenous steroids (the steroid profile), 19-norandrosterone, salbutamol and 11-nor-Δ9-tetrahydrocannabinol.9carboxylic acid in the applicable ranges and to detect qualitatively over 140 substances in accordance with the minimum required performance levels of the World Anti-Doping Agency in 1ml of urine. The classes of substances included in the method are anabolic steroids, β2-agonists, stimulants, narcotics, hormone antagonists and modulators and beta-blockers. Moreover, using a short capillary column and hydrogen as a carrier gas the run time of the method is less than 8min. Copyright © 2010 Elsevier B.V. All rights reserved.

The properties of the wood-polystyrene interphase determined by inverse gas chromatography

Science.gov (United States)

John Simonsen; Zhenqiu Hong; Timothy G. Rials

1997-01-01

The properties of the interphase in wood-polymer composites are important determinants of the properties of the final composite. This study used inverse gas chromatography (IGC) to measure interphasal properties of composites of polystyrene and two types of wood fiber fillers and an inoranic substrate (CW) with varying amounts of surface coverage of polystyrene. Glass...

Determination of binding-dioxygen in dioxygen complexes by headspace gas chromatography.

Science.gov (United States)

Wang, Wei; Feng, Shun; Li, Ya-ni; Wu, Meiying; Wang, Jide

2008-06-06

Dioxygen complexes play important roles in organisms' bodies, so the determination of binding-dioxygen has practical significance. A simple and robust method based on headspace gas chromatography was proposed to determine the binding-dioxygen in dioxygen complexes. By measuring the content change of nitrogen gas in a vial, the amount of oxygen released from dixoygen complexes can be determined. The method was validated using potassium chlorate as model sample, and the results exhibited good recoveries (90-99%) with the relative standard deviation less than 8%. It was also used to analyze dioxygen complex of cobalt bis(salicylaldehyde) ethylenediimine and polyamine cobalt complexes prepared by solid-phase reaction.

Possibilities of gas-phase radio-chromatography application to permanent-gas analysis; Possibilites de la radiochromatographie en phase gazeuse applications a l'analyse des gaz permanents

Energy Technology Data Exchange (ETDEWEB)

Dupuis, M C; Charrier, G; Alba, C; Massimino, D [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes

1970-07-01

The gas-phase radio-chromatography technique has been applied to the rapid analysis of permanent gases (H{sub 2}, O{sub 2}, N{sub 2}, A, Kr, Xe, CO, CH{sub 4}) labelled with radioactive indicators ({sup 3}H, {sup 37}A, {sup 85}Kr, {sup 133}Xe). After calibration, the components of such a mixture can be identified and their concentrations measured in less than two hours, using a sample volume of from 0.1 to 10 cm{sup 3}. The minimum detectable activity is of the order of 10{sup -4} {mu}C for each radioactive isotope. The measurements are reproducible to about 2 to 3 per cent. This work has been mainly concerned with the influence of parameters affecting the response of the radioactivity detector (ionization chamber or gas flow proportional counter). The method has very numerous applications both theoretically, for the study of chromatographic phenomena under ideal conditions (infinitesimal concentrations made possible by the use of radioactive tracers), and practically, for rapid and accurate radiochemical analysis of radioactive gas mixtures. (authors) [French] La technique de radiochromatographie en phase gazeuse est appliquee a l'analyse rapide de gaz permanents (H{sub 2}, O{sub 2}, N{sub 2}, A, Kr, Xe, CO, CH{sub 4}) marques par des indicateurs radioactifs ({sup 3}H, {sup 37}A, {sup 85}Kr, {sup 133}Xe). Apres etalonnage, l'identification et la mesure des concentrations des constituants d'un tel melange requierent moins de deux heures, sur un volume d'echantillon de 0.1 a 10 cm{sup 3}. L'activite minimum detectable est de l'ordre de 10{sup -4} {mu}C pour chaque isotope radioactif. La reproductibilite des mesures est de l'ordre de 2 a 3 pour cent. L'etude porte principalement sur l'influence des parametres affectant la reponse du detecteur de radioactivite (chambre d'ionisation, ou compteur proportionnel a circulation). La methode est extremement fertile en applications tant sur le plan theorique pour l'etude du phenomene chromatographique dans les conditions

Rapid and sensitive determination of deuterium concentration by gas chromatography

International Nuclear Information System (INIS)

Takahashi, Tomiki; Ohokoshi, Sumio; Shinriki, Nariko; Sato, Toshio

1984-01-01

Gas chromatographic determination of hydrogen isotopes D 2 and HD has hitherto been carried out with a molecular sieve column kept at -195 0 C under the H 2 carrier gas. However, the amount of D 2 in hydrogen gas containing low HD concentration of less than 5 % can be practically neglected judging from the equilibrium constant of H 2 -D 2 exchange reaction. Therefore, there is no need to separate HD from D 2 . As an improvement, in this paper, the gas chromatographic determination of HD in low concentration ( 2 as a carrier gas enabled us to enhance the cell current of TCD drastically, hence gave rise to high sensitivity of HD detection. The limit of determination of the concentration of HD was 0.01%. In the case of the higher concentration (>5%) of HD in hydrogen gas, D 2 and HD have been separated and determined by the method described above, but this method takes more than ten minutes. Therefore, we designed a new gas chromatographic analysis of the HD-D 2 mixture with an activated alumina column at -195 0 C under the H 2 carrier gas (330 ml/min). The advantages of this method are in (1) rapid analysis (in 1 min), (2) no need of the rigid activation temperature ((110--250) 0 C), (3) no change of the relative molar sensitivity of HD to D 2 at the various flow rates of H 2 carrier gas ((100--300)ml/min). (author)

Genuineness assessment of mandarin essential oils employing gas chromatography-combustion-isotope ratio MS (GC-C-IRMS).

Science.gov (United States)

Schipilliti, Luisa; Tranchida, Peter Quinto; Sciarrone, Danilo; Russo, Marina; Dugo, Paola; Dugo, Giovanni; Mondello, Luigi

2010-03-01

Cold-pressed mandarin essential oils are products of great economic importance in many parts of the world and are used in perfumery, as well as in food products. Reconstituted mandarin oils are easy to find on the market; useful information on essential oil authenticity, quality, extraction technique, geographic origin and biogenesis can be attained through high-resolution GC of the volatile fraction, or enantioselective GC, using different chiral stationary phases. Stable isotope ratio analysis has gained considerable interest for the unveiling of citrus oil adulteration, detecting small differences in the isotopic carbon composition and providing plenty of information concerning the discrimination among products of different geographical origin and the adulteration of natural essential oils with synthetic or natural compounds. In the present research, the authenticity of several mandarin essential oils was assessed through the employment of GC hyphenated to isotope ratio MS, conventional GC flame ionization detector, enantioselective GC and HPLC. Commercial mandarin oils and industrial natural (declared as such) mandarin essential oils, characterized by different harvest periods and geographic origins, were subjected to analysis. The results attained were compared with those of genuine cold-pressed Italian mandarin oils, obtained during the 2008-2009 harvest season.

On-line monitoring of benzene air concentrations while driving in traffic by means of isotopic dilution gas chromatography/mass spectrometry.

Science.gov (United States)

Davoli, E; Cappellini, L; Moggi, M; Ferrari, S; Fanelli, R

1996-01-01

There is no shortage of information about the average benzene concentrations in urban air, but there is very little about microenvironmental exposure, such as in-vehicle concentrations while driving in various traffic conditions, while refuelling, or while in a parking garage. The main reason for this lack of data is that no analytical instrumentation has been available to measure on-line trace amounts of benzene in such situations. We have recently proposed a highly accurate, high-speed cryofocusing gas chromatography/mass spectrometry (GC/MS) system for monitoring benzene concentrations in air. Accuracy of the analytical data is achieved by enrichment of the air sample before trapping, with a stable isotope permeation tube system. The same principles have been applied to a new instrument, specifically designed for operation on an electric vehicle (Ducato Elettra, Fiat). The zero emission vehicle and the fully transportable, battery-operated GC/MS system provide a unique possibility of monitoring benzene exposure in real everyday situations such as while driving, refuelling, or repairing a car. All power consumptions have been reduced so as to achieve a battery-operated GC/MS system. Liquid nitrogen cryofocusing has been replaced by a packed, inductively heated, graphitized charcoal microtrap. The instrument has been mounted on shock absorbers and installed in the van. The whole system has been tested in both fixed and mobile conditions. The maximum monitoring period without external power supply is 6 h. The full analytical cycle is 4 min, allowing close to real-time monitoring, and the minimum detectable level is 1 microgram/m3 for benzene. In-vehicle monitoring showed that, when recirculation was off and ventilation on, i.e., air from outside the vehicle was blown inside, concentrations varied widely in different driving conditions: moving from a parking lot into normal traffic on an urban traffic condition roadway yielded an increase in benzene concentration

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

Science.gov (United States)

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…

Analysis of the chemical composition of the essential oils extracted from Lippia lacunosa Mart. and Schauer and Lippia rotundifolia Cham. (Verbenaceae) by gas chromatography and gas chromatography-mass spectrometry

International Nuclear Information System (INIS)

Leitao, Suzana G.; Barbosa, Ymira Galico; Viccini, Lyderson F.; Salimena, Fatima R.G.; Peixoto, Paulo H.P.

2008-01-01

Lippia lacunosa and L. rotundifolia (Verbenaceae) are two Brazilian species of complex taxonomic delimitation. The composition of the essential oils from leaves and flowers of these plants was investigated by gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC-MS) analysis. The major components of the essential oils of flowers and leaves of L. lacunosa were: myrcene (14.7% and 11.9%), myrcenone (45.2% and 64.2%), Z-ocimenone (5.7% and 5.2%), and E-ocimenone (14.7% and 4.1%), respectively; whereas in L. rotundifolia (flowers and leaves) were ..-pinene (8.7% and 1.8%), myrcene (5.1% and 3.6%), limonene (26.0% and 7.9 %), cis-pinocamphone (4.5% and 3.1%) and myrtenal (22.3% and 16.7%), respectively. The essential oils from L. lacunosa exhibited a strong and pleasant mango aroma, which was related to the presence of myrcene and myrcenone. The marked differences in the chemical composition of their essential oils may represent a powerful tool for the botanical classification. (author)

Analysis of the chemical composition of the essential oils extracted from Lippia lacunosa Mart. and Schauer and Lippia rotundifolia Cham. (Verbenaceae) by gas chromatography and gas chromatography-mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Leitao, Suzana G.; Barbosa, Ymira Galico [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Fac. de Farmacia; Oliveira, Danilo R. de; Leitao, Gilda G. [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Nucleo de Pesquisas de Produtos Naturais]. E-mail: sgleitao@pharma.ufrj.br; Suelsen, Valeria; Martino, Virginia [Universidad de Buenos Aires (Argentina). Facultad de Farmacia y Bioquimica; Bizzo, Humberto R.; Lopes, Daise [EMBRAPA Agroindustria de Alimentos, Rio de Janeiro, RJ (Brazil); Viccini, Lyderson F.; Salimena, Fatima R.G.; Peixoto, Paulo H.P. [Universidade Federal de Juiz de Fora (UFJF), Juiz de Fora, MG (Brazil). Inst. de Ciencias Biolgicas

2008-07-01

Lippia lacunosa and L. rotundifolia (Verbenaceae) are two Brazilian species of complex taxonomic delimitation. The composition of the essential oils from leaves and flowers of these plants was investigated by gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC-MS) analysis. The major components of the essential oils of flowers and leaves of L. lacunosa were: myrcene (14.7% and 11.9%), myrcenone (45.2% and 64.2%), Z-ocimenone (5.7% and 5.2%), and E-ocimenone (14.7% and 4.1%), respectively; whereas in L. rotundifolia (flowers and leaves) were ..-pinene (8.7% and 1.8%), myrcene (5.1% and 3.6%), limonene (26.0% and 7.9 %), cis-pinocamphone (4.5% and 3.1%) and myrtenal (22.3% and 16.7%), respectively. The essential oils from L. lacunosa exhibited a strong and pleasant mango aroma, which was related to the presence of myrcene and myrcenone. The marked differences in the chemical composition of their essential oils may represent a powerful tool for the botanical classification. (author)

Multiplex gas chromatography: an alternative concept for gas chromatographic analysis of planetary atmospheres

Science.gov (United States)

Valentin, J. R.

1989-01-01

Gas chromatography (GC) is a powerful technique for analyzing gaseous mixtures. Applied to the earth's atmosphere, GC can be used to determine the permanent gases--such as carbon dioxide, nitrogen, and oxygen--and to analyze organic pollutants in air. The U.S. National Aeronautics and Space Administration (NASA) has used GC in spacecraft missions to Mars (the Viking Biology Gas Exchange Experiment [GEX] and the Viking Gas Chromatograph-Mass Spectrometer [GC-MS]) and to Venus (the Pioneer Venus Gas Chromatograph [PVGC] on board the Pioneer Venus sounder probe) for determining the atmospheric constituents of these two planets. Even though conventional GC was very useful in the Viking and Pioneer missions, spacecraft constraints and limitations intrinsic to the technique prevented the collection of more samples. With the Venus probe, for instance, each measurement took a relatively long time to complete (10 min), and successive samples could not be introduced until the previous samples had left the column. Therefore, while the probe descended through the Venusian atmosphere, only three samples were acquired at widely separated altitudes. With the Viking mission, the sampling rate was not a serious problem because samples were acquired over a period of one year. However, the detection limit was a major disadvantage. The GC-MS could not detect simple hydrocarbons and simple alcohols below 0.1 ppm, and the GEX could not detect them below 1 ppm. For more complex molecules, the detection limits were at the parts-per-billion level for both instruments. Finally, in both the Viking and Pioneer missions, the relatively slow rate of data acquisition limited the number of analyses, and consequently, the amount of information returned. Similar constraints are expected in future NASA missions. For instance, gas chromatographic instrumentation is being developed to collect and analyze organic gases and aerosols in the atmosphere of Titan (one of Saturn's satellites). The Titan

Ion counting method and it's operational characteristics in gas chromatography-mass spectrometry

International Nuclear Information System (INIS)

Fujii, Toshihiro

1976-01-01

Ion counting method with continuous channel electron multiplier which affords the direct detection of very small ion currents and it's operational characteristics were studied in gas chromatography-mass spectrometry. Then this method was applied to the single ion detection technique of GC-MS. A detection limit was measured, using various standard samples of low level concentration. (auth.)

[Recent advances in analysis of petroleum geological samples by comprehensive two-dimensional gas chromatography].

Science.gov (United States)

Gao, Xuanbo; Chang, Zhenyang; Dai, Wei; Tong, Ting; Zhang, Wanfeng; He, Sheng; Zhu, Shukui

2014-10-01

Abundant geochemical information can be acquired by analyzing the chemical compositions of petroleum geological samples. The information obtained from the analysis provides scientifical evidences for petroleum exploration. However, these samples are complicated and can be easily influenced by physical (e. g. evaporation, emulsification, natural dispersion, dissolution and sorption), chemical (photodegradation) and biological (mainly microbial degradation) weathering processes. Therefore, it is very difficult to analyze the petroleum geological samples and they cannot be effectively separated by traditional gas chromatography/mass spectrometry. A newly developed separation technique, comprehensive two-dimensional gas chromatography (GC x GC), has unique advantages in complex sample analysis, and recently it has been applied to petroleum geological samples. This article mainly reviews the research progres- ses in the last five years, the main problems and the future research about GC x GC applied in the area of petroleum geology.

Evaluation of the plasma hydrogen isotope content by residual gas analysis at JET and AUG

Science.gov (United States)

Drenik, A.; Alegre, D.; Brezinsek, S.; De Castro, A.; Kruezi, U.; Oberkofler, M.; Panjan, M.; Primc, G.; Reichbauer, T.; Resnik, M.; Rohde, V.; Seibt, M.; Schneider, P. A.; Wauters, T.; Zaplotnik, R.; ASDEX-Upgrade, the; EUROfusion MST1 Teams; contributors, JET

2017-12-01

The isotope content of the plasma reflects on the dynamics of isotope changeover experiments, efficiency of wall conditioning and the performance of a fusion device in the active phase of operation. The assessment of the isotope ratio of hydrogen and methane molecules is used as a novel method of assessing the plasma isotope ratios at JET and ASDEX-Upgrade (AUG). The isotope ratios of both molecules in general shows similar trends as the isotope ratio detected by other diagnostics. At JET, the absolute values of RGA signals are in relatively good agreement with each other and with spectroscopy data, while at AUG the deviation from neutral particle analyser data are larger, and the results show a consistent spatial distribution of the isotope ratio. It is further shown that the isotope ratio of the hydrogen molecule can be used to study the degree of dissociation of the injected gas during changeover experiments.

Simultaneous determination of wine sugars, glycerol and organic acids 13C/12C isotopic ratio by ion chromatography-co-IRMS

Directory of Open Access Journals (Sweden)

Guyon Francois

2014-01-01

Full Text Available Ion chromatography (IC isotope ratio mass spectrometry (IRMS coupling is possible using a liquid interface allowing chemical oxidation (co of organic compounds. Synthetic solutions containing a mixture of glycerol, sugars (sucrose, glucose and fructose and organic acids (gluconic, lactic, malic, tartaric, oxalic, fumaric, citric and isocitric were elaborated to estimate analytical applications of two different IC systems. It appears that the use of carbonated solution in the eluting phase is a perturbation for 13C isotope measurements as it creates a δ13C deviation from the expected values. A sample of authentic sweet wine was analyzed by IC-co-IRMS using KOH gradient. Ratios of isotopic, ratios of organic acids and glycerol was found to be, in average, equal 1.01 ± 0.04 that is in accordance with our previous results.

Investigation of surface properties of physico-chemically modified natural fibres using inverse gas chromatography

CSIR Research Space (South Africa)

Cordeiro, N

2011-01-01

Full Text Available Inverse gas chromatography (IGC) is a suitable method to determine surface energy of natural fibres when compared to wetting techniques. In the present study, the surface properties of raw and modified lignocellulosic fibres have been investigated...

Characterization of some Jordanian oil shales by pyrolysis gas chromatography

International Nuclear Information System (INIS)

Jaradat, Q. M.

1995-01-01

Gas chromatography with flame ionization detector (GC-FID) was used to study pyrolysis of some Jordanian oil shale samples. Three sampls of different altitudes from El-Lajjun were studied. Pyrograms of solid sampls were studied at different temperature profiles. Solid-liquid extraction with water, methanol, or hexane allowed extraction of organics of different polarity. Hexane showed the highest extraction efficiency. Reproducibility of the pyrograms of the solid sample was evalualted. Relative standard deviation was 7.56%. (author). 7 refs., 8 figs

Identification of key aromatic compounds in Congou black tea by PLSR with variable importance of projection scores and gas chromatography-mass spectrometry/gas chromatography-olfactometry.

Science.gov (United States)

Mao, Shihong; Lu, Changqi; Li, Meifeng; Ye, Yulong; Wei, Xu; Tong, Huarong

2018-04-13

Gas chromatography-olfactometry (GC-O) is the most frequently used method to estimate the sensory contribution of single odorant, but disregards the interactions between volatiles. In order to select the key volatiles responsible for the aroma attributes of Congou black tea (Camellia sinensis), instrumental, sensory and multivariate statistical approaches were applied. By sensory analysis, nine panelists developed 8 descriptors, namely, floral, sweet, fruity, green, roasted, oil, spicy, and off-odor. Linalool, (E)-furan linalool oxide, (Z)-pyran linalool oxide, methyl salicylate, β-myrcene, phenylethyl alcohol which identified from the most representative samples by GC-O procedure, were the essential aroma-active compounds in the formation of basic Congou black tea aroma. In addition, 136 volatiles were identified by gas chromatography-mass spectrometry (GC-MS), among which 55 compounds were determined as the key factors for the six sensory attributes by partial least-square regression (PLSR) with variable importance of projection (VIP) scores. Our results demonstrated that HS-SPME/GC-MS/GC-O was a fast approach for isolation and quantification aroma-active compounds. PLSR method was also considered to be a useful tool in selecting important variables for sensory attributes. These two strategies allowed us to comprehensively evaluate the sensorial contribution of single volatile from different perspectives, can be applied to related products for comprehensive quality control. This article is protected by copyright. All rights reserved.

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

Science.gov (United States)

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…

Extraction chromatography of fission products

International Nuclear Information System (INIS)

Bonnevie-Svendsen, M.; Goon, K.

1978-01-01

Various cases of using extraction chromatography during analysis of fission products are reviewed. The use of the extraction chromatography method is considered while analysing reprocessed products of nuclear fuel for quantitative radiochemical analysis and control of fission product and actinoide separation during extraction and their chemical state in production solutions. The method is used to obtain pure fractions of typical burnup monitors (neodymium, molybdenum, cerium, cesium, europium, lanthanides) during determination of nuclear fuel burnup degree. While studying the nature of nuclear reactions the method is used to separate quickly short-life isotopes, to purify β-radiator fractions before measuring their half-life periods, to enrich isotopes forming with low output during fission. Examples of using extraction chromatography are given to separate long half-life or stable fission products from spent solutions, to control environment object contamination

Gas chromatography vs. quantum cascade laser-based N2O flux measurements using a novel chamber design

DEFF Research Database (Denmark)

Bruemmer, Christian; Lyshede, Bjarne; Lempio, Dirk

2017-01-01

automated chamber system against a conventional gas chromatography (GC) approach using the same chambers plus an automated gas sampling unit with septum capped vials and subsequent laboratory GC analysis. Through its high precision and time resolution, data of the QCL system were used for quantifying...

A simple method for the measurement of radioactivity of samples separated by gas chromatography

International Nuclear Information System (INIS)

Farkas, T.

1981-01-01

Gas chromatographs with flame ionization detector can be used to determine the radioactivity ( 14 C) of separated peaks. After a suitable change in the detector output the combustion product 14 CO 2 can be trapped by hyamine hydroxyde and measured by liquid scintigraphy. 90% of peak activity can be collected and measured, thus the method can be applied to determine the distribution and specific radioactivity of the components separated by gas chromatography. (author)

Stable isotopes

International Nuclear Information System (INIS)

Brazier, J.L.; Guinamant, J.L.

1995-01-01

According to the progress which has been realised in the technology of separating and measuring isotopes, the stable isotopes are used as preferable 'labelling elements' for big number of applications. The isotopic composition of natural products shows significant variations as a result of different reasons like the climate, the seasons, or their geographic origins. So, it was proved that the same product has a different isotopic composition of alimentary and agriculture products. It is also important in detecting the pharmacological and medical chemicals. This review article deals with the technology, like chromatography and spectrophotometry, adapted to this aim, and some important applications. 17 refs. 6 figs

Formic acid hydrolysis/liquid chromatography isotope dilution mass spectrometry: An accurate method for large DNA quantification.

Science.gov (United States)

Shibayama, Sachie; Fujii, Shin-Ichiro; Inagaki, Kazumi; Yamazaki, Taichi; Takatsu, Akiko

2016-10-14

Liquid chromatography-isotope dilution mass spectrometry (LC-IDMS) with formic acid hydrolysis was established for the accurate quantification of λDNA. The over-decomposition of nucleobases in formic acid hydrolysis was restricted by optimizing the reaction temperature and the reaction time, and accurately corrected by using deoxynucleotides (dNMPs) and isotope-labeled dNMPs as the calibrator and the internal standard, respectively. The present method could quantify λDNA with an expanded uncertainty of 4.6% using 10fmol of λDNA. The analytical results obtained with the present method were validated by comparing with the results of phosphate-base quantification by inductively coupled plasma-mass spectrometry (ICP-MS). The results showed good agreement with each other. We conclude that the formic acid hydrolysis/LC-IDMS method can quantify λDNA accurately and is promising as the primary method for the certification of DNA as reference material. Copyright © 2016 Elsevier B.V. All rights reserved.

Possibilities of gas-phase radio-chromatography application to permanent-gas analysis; Possibilites de la radiochromatographie en phase gazeuse applications a l'analyse des gaz permanents

Energy Technology Data Exchange (ETDEWEB)

Dupuis, M.C.; Charrier, G.; Alba, C.; Massimino, D. [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes

1970-07-01

The gas-phase radio-chromatography technique has been applied to the rapid analysis of permanent gases (H{sub 2}, O{sub 2}, N{sub 2}, A, Kr, Xe, CO, CH{sub 4}) labelled with radioactive indicators ({sup 3}H, {sup 37}A, {sup 85}Kr, {sup 133}Xe). After calibration, the components of such a mixture can be identified and their concentrations measured in less than two hours, using a sample volume of from 0.1 to 10 cm{sup 3}. The minimum detectable activity is of the order of 10{sup -4} {mu}C for each radioactive isotope. The measurements are reproducible to about 2 to 3 per cent. This work has been mainly concerned with the influence of parameters affecting the response of the radioactivity detector (ionization chamber or gas flow proportional counter). The method has very numerous applications both theoretically, for the study of chromatographic phenomena under ideal conditions (infinitesimal concentrations made possible by the use of radioactive tracers), and practically, for rapid and accurate radiochemical analysis of radioactive gas mixtures. (authors) [French] La technique de radiochromatographie en phase gazeuse est appliquee a l'analyse rapide de gaz permanents (H{sub 2}, O{sub 2}, N{sub 2}, A, Kr, Xe, CO, CH{sub 4}) marques par des indicateurs radioactifs ({sup 3}H, {sup 37}A, {sup 85}Kr, {sup 133}Xe). Apres etalonnage, l'identification et la mesure des concentrations des constituants d'un tel melange requierent moins de deux heures, sur un volume d'echantillon de 0.1 a 10 cm{sup 3}. L'activite minimum detectable est de l'ordre de 10{sup -4} {mu}C pour chaque isotope radioactif. La reproductibilite des mesures est de l'ordre de 2 a 3 pour cent. L'etude porte principalement sur l'influence des parametres affectant la reponse du detecteur de radioactivite (chambre d'ionisation, ou compteur proportionnel a circulation). La methode est extremement fertile en applications tant sur le plan theorique pour l

On the interference of Kr during carbon isotope analysis of methane using continuous-flow combustion–isotope ratio mass spectrometry

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J. Schmitt

2013-05-01

Full Text Available Stable carbon isotope analysis of methane (δ13C of CH4 on atmospheric samples is one key method to constrain the current and past atmospheric CH4 budget. A frequently applied measurement technique is gas chromatography (GC isotope ratio mass spectrometry (IRMS coupled to a combustion-preconcentration unit. This report shows that the atmospheric trace gas krypton (Kr can severely interfere during the mass spectrometric measurement, leading to significant biases in δ13C of CH4, if krypton is not sufficiently separated during the analysis. According to our experiments, the krypton interference is likely composed of two individual effects, with the lateral tailing of the doubly charged 86Kr peak affecting the neighbouring m/z 44 and partially the m/z 45 Faraday cups. Additionally, a broad signal affecting m/z 45 and especially m/z 46 is assumed to result from scattered ions of singly charged krypton. The introduced bias in the measured isotope ratios is dependent on the chromatographic separation, the krypton-to-CH4 mixing ratio in the sample, the focusing of the mass spectrometer as well as the detector configuration and can amount to up to several per mil in δ13C. Apart from technical solutions to avoid this interference, we present correction routines to a posteriori remove the bias.

Continuous-flow isotope ratio mass spectrometry method for carbon and hydrogen isotope measurements on atmospheric methane

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M. Brass

2010-12-01

Full Text Available We describe a continuous-flow isotope ratio mass spectrometry (CF-IRMS technique for high-precision δD and δ¹³C measurements of atmospheric methane on 40 mL air samples. CH₄ is separated from other air components by utilizing purely physical processes based on temperature, time and mechanical valve switching. Chemical agents are avoided. Trace amounts of interfering compounds can be separated by gas chromatography after pre-concentration of the CH₄ sample. The purified sample is then either combusted to CO₂ or pyrolyzed to H₂ for stable isotope measurement. Apart from connecting samples and refilling liquid nitrogen as coolant the system is fully automated and allows an unobserved, continuous analysis of samples. The analytical system has been used for analysis of air samples with CH₄ mixing ratios between ~100 and ~10 000 ppb, for higher mixing ratios samples usually have to be diluted.

Zinc isotope separation in acetone by displacement chromatography using benzo-15-crown-5 resin

International Nuclear Information System (INIS)

Ding Xingcheng; Tatsuya Suzuki; Masao Nomura; Yashuhiko Fujii

2005-01-01

Zinc is considered as a useful material for cooling water treatment in light water plants. Injection of 64 Zn depleted Zinc is expected to further reduce the radiation in the reactor water system. For such a purpose of Zinc isotope separation, chemical exchange method has been studied. Breakthrough methods of chromatography experiments were performed. 0.5 mol/dm 3 ZnCl 2 dissolved in acetone solution was fed to glass columns packed with benzo-15-crown-5 resin at 35 degree C. The effluent was collected in fractions of which zinc concentration was determined by atomic adsorption spectrometer and isotope ratio was measured by ICP-MS. Observed enrichment ratios defined as, ( i Zn/ 64 Zn) sample / ( i Zn/ 64 Zn) original , where i=66,68, are plotted in Figure. From the results of experiment, it was confirmed that heavier zinc is preferentially enriched in the eluted samples of front band regions. The separation coefficient (ε) for 66 Zn/ 64 Zn and 68 Zn/ 64 Zn of five meters migration was obtained as 5.2 x 10 -4 and 8.1 x 10 -4 , respectively. The error is estimated to be 20% of the values.

Research on the separation properties of empty-column gas chromatography (EC-GC) and conditions for simulated distillation (SIMDIS).

Science.gov (United States)

Boczkaj, Grzegorz; Kamiński, Marian

2013-10-01

Previous studies have revealed it is possible to separate a high-boiling mixture by gas chromatography in empty fused-silica capillary tubing rather than in columns coated with stationary phase. Chromatographic separation occurs solely on the basis of the different boiling points of the substances separated. The high similarity of such separations to those in classic distillation seems advantageous when gas chromatography is used for simulated distillation. This paper presents results from further research on the separation properties of empty fused silica tubing. The efficiency of this chromatographic system has been examined. The usefulness of such conditions has been studied for simulated distillation, i.e. to determine the boiling-point distribution of complex mixtures, mainly petroleum fractions and products, on the basis of their retention relative to reference substances. The results obtained by use of empty-column gas chromatography (EC-GC) and by use of classical simulated distillation columns have been compared for solutes of different polarity. Studies revealed boiling points determined by EC-GC were more accurate than those obtained by the standard method of simulated distillation.

Changes in the basic experimental parameters of capillary gas chromatography in the 20th century.

Science.gov (United States)

Berezkin, V G; Viktorova, E N

2003-01-24

Studies of qualitative changes in capillary gas chromatography are of significant practical and scientific interest. This paper analyzes the evolution of the most important experimental chromatographic parameters over the last three decades and is based on the use of a new approach to scientometrical research that is referred to as applied scientometry. One essential feature of this approach is that it looks at the entire contents of each paper rather than only taking account its title, abstract. and references (as is typical for conventional scientometry). In this paper, we monitor how the most important chromatographic parameters, such as column length and diameter, layer thickness, stationary liquid phases, separation temperature mode. etc., have been evolving over the period 1970-2000. We used data from the following journals: Chromatographia, Journal of Chromatography, and Journal of High Resolution Chromatography and Chromatography Communications.

Comparison of the quantification of caffeine in human plasma by gas chromatography and ELISA

Directory of Open Access Journals (Sweden)

A.B. Carregaro

2001-06-01

Full Text Available In the present study we evaluated the precision of the ELISA method to quantify caffeine in human plasma and compared the results with those obtained by gas chromatography. A total of 58 samples were analyzed by gas chromatography using a nitrogen-phosphorus detector and routine techniques. For the ELISA test, the samples were diluted to obtain a concentration corresponding to 50% of the absorbance of the standard curve. To determine whether the proximity between the I50 of the standard curve and that of the sample would bring about a more precise result, the samples were divided into three blocks according to the criterion of difference, in modulus, of the I50 of the standard curve and of the I50 of the sample. The samples were classified into three groups. The first was composed of 20 samples with I50 up to 1.5 ng/ml, the second consisted of 21 samples with I50 ranging from 1.51 to 3 ng/ml, and the third of 17 samples with I50 ranging from 3.01 to 13 ng/ml. The determination coefficient (R² = 0.999 showed that the data obtained by gas chromatography represented a reliable basis. The results obtained by ELISA were also reliable, with an estimated Pearson correlation coefficient of 0.82 between the two methods. This coefficient for the different groups (0.88, 0.79 and 0.49 for groups 1, 2 and 3, respectively showed greater reliability for the test with dilutions closer to I50.

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

Science.gov (United States)

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...

Fractionation of mercury stable isotopes during coal combustion and seawater flue gas desulfurization

International Nuclear Information System (INIS)

Huang, Shuyuan; Yuan, Dongxing; Lin, Haiying; Sun, Lumin; Lin, Shanshan

2017-01-01

In the current study, fractionation of mercury isotopes during coal combustion and seawater flue gas desulfurization (SFGD) in a coal-fired power plant using a SFGD system was investigated. Fourteen samples were collected from the power plant. The samples were pretreated with a combustion-trapping method and were analyzed with a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS). Compared with the raw coal, the bottom ash was enriched with lighter mercury isotopes with δ 202 Hg values ranging from −0.45 to −0.03‰. The fly ash was enriched with lighter mercury isotopes with δ 202 Hg values ranging from −1.49 to −0.73‰ for Chinese coal and from −1.47 to −0.62‰ for Indonesian coal. The δ 202 Hg of fresh seawater and desulfurized seawater was found to be −1.32 and −0.32‰ respectively. These δ 202 Hg values indicated that the desulfurized seawater was enriched with heavier mercury isotopes. Based upon the calculated results obtained from the mass balance equation, it was suggested that the stack emissions were enriched with lighter mercury isotopes. Mass independent fractionation was observed in most of the samples with a Δ 199 Hg/Δ 201 Hg ratio of approximately 0.96. The results help in improving the understanding of mercury isotope fractionation during coal combustion and SFGD, and are also useful in tracing the mercury emissions from coal fired power plants. - Highlights: • Spread of 1.5‰ was observed in δ 202 Hg values of raw coals and coal related samples. • The δ 202 Hg values were more negative in fly ash than those in the raw coal. • The flue gas had a significant Hg fractionation after desulfurization. • The stack emissions were enriched with lighter isotopes compared with the raw coal.

ENVIRONMENTAL ANALYSIS BY AB INITIO QUANTUM MECHANICAL COMPUTATION AND GAS CHROMATOGRAPHY/FOURIER TRANSFORM INFRARED SPECTROMETRY.

Science.gov (United States)

Computational chemistry, in conjunction with gas chromatography/mass spectrometry/Fourier transform infrared spectrometry (GC/MS/FT-IR), was used to tentatively identify seven tetrachlorobutadiene (TCBD) isomers detected in an environmental sample. Computation of the TCBD infrare...

Fast methods for screening of trichothecenes in fungal cultures using gas chromatography-tandem mass spectrometry

DEFF Research Database (Denmark)

Nielsen, Kristian Fog; Thrane, Ulf

2001-01-01

The paper presents a fast method for trichothecene profiling and chemotaxonomic studies in species of Fusarium, Stachybotrys, Trichoderma and Memnoniella. Micro scale extracted crude Fusarium extracts were derivatised using pentafluoropropionic anhydride and analysed by gas chromatography...

[Determination of residual solvents in 7-amino-3-chloro cephalosporanic acid by gas chromatography].

Science.gov (United States)

Ma, Li; Yao, Tong-wei

2011-01-01

To develop a gas chromatography method for determination of residual solvents in 7-amino-3-chloro cephalosporanic acid (7-ACCA). The residual levels of acetone, methanol, dichloromethane, ethyl acetate, isobutanol, pyridine and toluene in 7-ACCA were measured by gas chromatography using Agilent INNOWAX capillary column (30 m × 0.32 mm,0.5 μm). The initial column temperature was 70° maintained for 6 min and then raised (10°C/min) to 160°C for 1 min. Nitrogen gas was used as carrier and FID as detector. The flow of carrier was 1.0 ml/min, the temperature of injection port and detector was 200°C and 250°C, respectively. The limits of detection for acetone, methanol, dichloromethane, ethyl acetate, isobutanol, pyridine, toluene in 7-ACCA were 2.5 μg/ml, 1.5 μg/ml, 15 μg/ml, 2.5 μg/ml, 2.5 μg/ml, 2.5 μg/ml and 11 μg/ml, respectively. Only acetone was detected in the sample, and was less than the limits of Ch.P. The method can effectively detect the residual solvents in 7-ACCA.

Detection of radiation-induced hydrocarbons in irradiated fish and prawns by means of on-line coupled liquid chromatography-gas chromatography

International Nuclear Information System (INIS)

Schulzki, G.; Spiegelberg, A.; Bogl, K.W.; Schreiberg, G.A.

1997-01-01

Radiation-induced hydrocarbons were analyzed in a fatty (halibut) and a lean fish (cod) as well as in a prawn species by on-line coupled liquid chromatography (LC) -gas chromatography (GC) combined with mass spectrometry. In irradiated halibut which is known to contain mainly saturated and monounsaturated fatty acids, all expected radiolytic alkanes, alkenes, and alkadienes could be detected. The yields of the C(n-1) and C(n-2:1) hydrocarbons were comparable to those found in irradiated lipids of terrestrial animals and plants. However, in cod and prawns which contain high levels of polyunsaturated fatty acids (PUFA), the C(n-1) hydrocarbons were found in concentrations which were up to 10 times higher whereas the C(n-2:1) products were again comparable to those of terrestrial animals and plants. The identification of radiation-induced hydrocarbons in fish lipids was achieved by transfer of the hydrocarbons from the LC column to the gas chromatographic column in fractions differing in their degree of unsaturation. For the first time, radiation-induced hydrocarbons with more than four double bonds generated from polyunsaturated fatty acids (20:4 omega 6 and 20:5 omega 3) could be identified

Selective detection of carbon-13, nitrogen-15, and deuterium labeled metabolites by capillary gas chromatography-chemical reaction interface/mass spectrometry

International Nuclear Information System (INIS)

Chace, D.H.; Abramson, F.P.

1989-01-01

We have applied a new chemical reaction interface/mass spectrometer technique (CRIMS) to the selective detection of 13C-, 15N-, and 2H-labeled phenytoin and its metabolites in urine following separation by capillary gas chromatography. The microwave-powered chemical reaction interface converts materials from their original forms into small molecules whose mass spectra serve to identify and quantify the nuclides that make up each analyte. The presence of each element is followed by monitoring the isotopic variants of CO2, NO, or H2 that are produced by the chemical reaction interface. Chromatograms showing only enriched 13C and 15N were produced by subtracting the abundance of naturally occurring isotopes from the observed M + 1 signal. A selective chromatogram of 2H (D) was obtained by measuring HD at m/z 3.0219 with a resolution of 2000. Metabolites representing less than 1.5% of the total labeled compounds could be identified in the chromatogram. Detection limits from urine of 380 pg/mL of a 15N-labeled metabolite, 7 ng/mL of a 13C-labeled metabolite, and 16 ng/mL of a deuterium labeled metabolite were determined at a signal to noise ratio of 2. Depending on the isotope examined, a linear dynamic range of 250-1000 was observed using CRIMS. To identify many of these labeled peaks (metabolites), the chromatographic analysis was repeated with the chemical reaction interface turned off and mass spectra obtained at the retention times found in the CRIMS experiment. CRIMS is a new analytical method that appears to be particularly useful for metabolism studies

Determination of cholesterol and four phytosterols in foods without derivatization by gas chromatography-tandem mass spectrometry

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Yan-Zong Chen

2015-12-01

Full Text Available In this study, a method for determination of cholesterol and four phytosterols by gas chromatography coupled with electron impact ionization mode–tandem mass spectrometry without derivatization in general food was developed. The sample was saponified with 7.5% KOH in methanol. After heating on hot plate and reflux for 60 minutes, the saponified portion was extracted with n-hexane/petroleum ether (50:50, v/v. The extracts were evaporated with rotary evaporator and then redissolved with tetrahydrofuran. The tetrahydrofuran layer was transferred into an injection vial and analyzed by gas chromatography on a 30 m VF-5 column. Limit of quantification was 2 mg/kg. Recoveries of cholesterol and four phytosterols from general food were between 91% and 100%.

The gas-liquid chromatography of carboxylic acid esters of the urinary 11-deoxy-17-oxo steroids. Determination as n-butyrates.

Science.gov (United States)

Sadler, P A; Kellie, A E

1967-06-01

1. The gas-liquid-chromatographic separations of the acetate, propionate, n-butyrate, isobutyrate and n-valerate esters of androsterone, aetiocholanolone and dehydroepiandrosterone were studied on a 1% neopentyl glycol sebacate column. The n-butyrate, isobutyrate and n-valerate esters were well resolved. 2. The three steroids derived from hydrolysed urinary 17-oxo steroid conjugate extracts were analysed by gas-liquid chromatography after conversion into their n-butyrate esters. The results were compared with independent determinations involving chromatography on alumina.

Selective data reduction in gas chromatography/infrared spectrometry

International Nuclear Information System (INIS)

Pyo, Dong Jin; Shin, Hyun Du

2001-01-01

As gas chromatography/infrared spectrometry (GC/IR) becomes routinely available, methods must be developed to deal with the large amount of data produced. We demonstrate computer methods that quickly search through a large data file, locating those spectra that display a spectral feature of interest. Based on a modified library search routine, these selective data reduction methods retrieve all or nearly all of the compounds of interest, while rejection the vast majority of unrelated compounds. To overcome the shifting problem of IR spectra, a search method of moving the average pattern was designed. In this moving pattern search, the average pattern of a particular functional group was not held stationary, but was allowed to be moved a little bit right and left

Analysis of small carbohydrates in several bioactive botanicals by gas chromatography with mass spectrometry and liquid chromatography with tandem mass spectrometry.

Science.gov (United States)

Moldoveanu, Serban; Scott, Wayne; Zhu, Jeff

2015-11-01

Bioactive botanicals contain natural compounds with specific biological activity, such as antibacterial, antioxidant, immune stimulating, and taste improving. A full characterization of the chemical composition of these botanicals is frequently necessary. A study of small carbohydrates from the plant materials of 18 bioactive botanicals is further described. The study presents the identification of the carbohydrate using a gas chromatographic-mass spectrometric analysis that allows detection of molecules as large as maltotetraose, after changing them into trimethylsilyl derivatives. A number of carbohydrates in the plant (fructose, glucose, mannose, sucrose, maltose, xylose, sorbitol, and myo-, chiro-, and scyllo-inositols) were quantitated using a novel liquid chromatography with tandem mass spectrometric technique. Both techniques involved new method developments. The gas chromatography with mass spectrometric analysis involved derivatization and separation on a Rxi(®)-5Sil MS column with H2 as a carrier gas. The liquid chromatographic separation was obtained using a hydrophilic interaction type column, YMC-PAC Polyamine II. The tandem mass spectrometer used an electrospray ionization source in multiple reaction monitoring positive ion mode with the detection of the adducts of the carbohydrates with Cs(+) ions. The validated quantitative procedure showed excellent precision and accuracy allowing the analysis in a wide range of concentrations of the analytes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Separation of cis- and trans-Asarone from Acorus tatarinowii by Preparative Gas Chromatography

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H. L. Zuo

2012-01-01

Full Text Available A preparative gas chromatography (pGC method was developed for the separation of isomers (cis- and trans-asarone from essential oil of Acorus tatarinowii. The oil was primarily fractionated by silica gel chromatography using different ratios of petroleum ether and ethyl acetate as gradient elution solvents. And then the fraction that contains mixture of the isomers was further separated by pGC. The compounds were separated on a stainless steel column packed with 10% OV-101 (3 m × 6 mm, i.d., and then the effluent was split into two gas flows. One percent of the effluent passed to the flame ionization detector (FID for detection and the remaining 99% was directed to the fraction collector. Two isomers were collected after 90 single injections (5 uL with the yield of 178 mg and 82 mg, respectively. Furthermore, the structures of the obtained compounds were identified as cis- and trans-asarone by 1H- and 13C-NMR spectra, respectively.

Determination of gamma-aminobutyric acid in food matrices by isotope dilution hydrophilic interaction chromatography coupled to mass spectrometry.

Science.gov (United States)

Zazzeroni, Raniero; Homan, Andrew; Thain, Emma

2009-08-01

The estimation of the dietary intake of gamma-aminobutyric acid (GABA) is dependent upon the knowledge of its concentration values in food matrices. To this end, an isotope dilution liquid chromatography-mass spectrometry method has been developed employing the hydrophilic interaction chromatography technique for analyte separation. This approach enabled accurate quantification of GABA in apple, potato, soybeans, and orange juice without the need of a pre- or post-column derivatization reaction. A selective and precise analytical measurement has been obtained with a triple quadrupole mass spectrometer operating in multiple reaction monitoring using the method of standard additions and GABA-d(6) as an internal standard. The concentrations of GABA found in the matrices tested are 7 microg/g of apple, 342 microg/g of potatoes, 211 microg/g of soybeans, and 344 microg/mL of orange juice.

Separation of boron isotopes by ion exchange chromatography: studies on regeneration of strong base anion exchange resins

International Nuclear Information System (INIS)

Sharma, B.K.; Subramanian, R.; Mathur, P.K.

1994-01-01

The optimum conditions for the regeneration of strong base anion exchange resins of type-I and type-II were determined for cost-effective separation of isotopes of boron by ion exchange chromatography where the hydroxyl form of an anion exchange resin is equilibrated with boric acid solution containing mannitol as a complexing reagent. The possibility of using unspent alkali content of the effluent was also exploited. Removal of carbonate impurity from Rayon grade caustic lye (used as regenerant after dilution) and recycling of Ba(OH) 2 was studied to avoid waste disposal problems. (author)

Measurement of rimantadine in plasma by capillary gas chromatography/mass spectrometry with a deuterium-labeled internal standard

International Nuclear Information System (INIS)

Herold, D.A.; Anonick, P.K.; Kinter, M.; Hayden, F.G.

1988-01-01

Rimantadine is a synthetic antiviral agent used in prophylaxis and in treating the early stages of uncomplicated influenza A illness. We describe a stable isotope-dilution assay involving capillary gas chromatography/mass spectrometry. We used 200 ng of d3-rimantadine, added to 1 mL of plasma, as the internal standard. The rimantadine was extracted from the plasma with a Bond-Elut CN column, the column was washed with water, and the rimantadine was eluted with methanol, dried, and treated to form the t-butyldimethylsilyl derivative. The mass spectrometer was operated in the selected ion monitoring mode. Ions at m/z 236 and m/z 239 were monitored, corresponding to the loss of C4H9 from the rimantadine derivative and d3-rimantadine, respectively. Within-run precision (CVs) ranged from 8.9% at 29 micrograms/L to 3.2% at 1666 micrograms/L. Corresponding data for between-run precision were 5.4% and 1.7%. Treated volunteers (n = 86) provided plasma samples with a concentration range of 153 to 1127 micrograms/L. This simplified method allows rapid, precise assay of rimantadine in plasma

Diesel characterization by high-resolution mass spectrometry - gas chromatography

International Nuclear Information System (INIS)

Baldrich, C.A

1998-01-01

High-resolution mass spectrometry-gas chromatography is combined with the HC22 method in order to obtain detailed information about the chemical composition of diesel and the distribution of different compound types in terms of its final boiling temperature from a single analysis. The total time elapsed from sample injection and signal processing to obtain final results is 90 minutes. This fact makes this methodology a new and very important tool for the decision making process concerning the most suitable final boiling temperature and the type of treatment of the product in order to obtain diesel that fulfills the international standards. The consistency and repeatability of the experimental results are demonstrated

Determination of acrylamide in Chinese traditional carbohydrate-rich foods using gas chromatography with micro-electron capture detector and isotope dilution liquid chromatography combined with electrospray ionization tandem mass spectrometry

International Nuclear Information System (INIS)

Zhang Yu; Ren Yiping; Zhao Hangmei; Zhang Ying

2007-01-01

The present study developed two analytical methods for quantification of acrylamide in complex food matrixes, such as Chinese traditional carbohydrate-rich foods. One is based on derivatization with potassium bromate and potassium bromide without clean-up prior to gas chromatography with micro-electron capture detector (GC-MECD). Alternatively, the underivatized acrylamide was detected by high-performance liquid chromatography coupled to quadrupole tandem mass spectrometry (HPLC-MS/MS) in the positive electrospray ionization mode. For both methods, the Chinese carbohydrate-rich samples were homogenized, defatted with petroleum ether and extracted with aqueous solution of sodium chloride. Recovery rates for acrylamide from spiked Chinese style foods with the spiking level of 50, 500 and 1000 μg kg -1 were in the range of 79-93% for the GC-MECD including derivatization and 84-97% for the HPLC-MS/MS method. Typical quantification limits of the HPLC-MSMS method were 4 μg kg -1 for acrylamide. The GC-MECD method achieved quantification limits of 10 μg kg -1 in Chinese style foods. Thirty-eight Chinese traditional foods purchased from different manufacturers were analyzed and compared with four Western style foods. Acrylamide contaminant was found in all of samples at the concentration up to 771.1 and 734.5 μg kg -1 detected by the GC and HPLC method, respectively. The concentrations determined with the two different quantitative methods corresponded well with each other. A convenient and fast pretreatment procedure will be optimized in order to satisfy further investigation of hundreds of samples

Hydrocarbon degassing of the earth and origin of oil-gas fields (isotope-geochemical and geodynamic aspects)

Science.gov (United States)

Valyaev, Boris; Dremin, Ivan

2016-04-01

More than half a century ago, Academician PN Kropotkin substantiated the relationship of the formation and distribution of oil and gas fields with the processes of emanation hydrocarbon degassing of the Earth. Over the years, the concept of PN Kropotkin received further development and recognition of studies based on new factual material. Of particular importance are the following factors: a) the results of studies on global and regional uneven processes of traditional oil and gas and the role of deep faults in controlling the spread of oil and gas fields; b) the results of the research on gigantic volumes and localization of the discharges of hydrocarbon fluids (mud volcanoes, seeps) on land and into the atmosphere and through the bottom of the World ocean; c) the results of the studies on grand volumes of the spread of unconventional hydrocarbon resources in their non-traditional fields, especially on near-surface interval of unconventional oil and gas accumulation with gas hydrates, heavy oil and bitumen, as well as extraordinary resources of oil and gas in the shale and tight rocks. Deep mantle-crust nature of oil and gas in traditional and nontraditional deposits thus received further substantiation of geological and geophysical data and research results. However, isotopic and geochemical data are still interpreted in favor of the concept of the genesis of oil and gas in the processes of thermal catalytic conversion of organic matter of sedimentary rocks, at temperatures up to 200°C. In this report an alternative interpretation of the isotope carbon-hydrogen system (δ13C-δD) for gas and of oil deposits, isotope carbon system for methane and carbon dioxide (δ13C1-δ13C0) will be presented. An alternative interpretation will also be presented for the data on carbon-helium isotope geochemical system for oil and gas fields, volcanoes and mud volcanoes. These constructions agree with the geological data on the nature of deep hydrocarbon fluids involved in the

Ion Mobility Mass Spectrometry Direct Isotope Abundance Analysis

International Nuclear Information System (INIS)

Manard, Manuel J.; Weeks, Stephan; Kyle, Kevin

2010-01-01

The nuclear forensics community is currently engaged in the analysis of illicit nuclear or radioactive material for the purposes of non-proliferations and attribution. One technique commonly employed for gathering nuclear forensics information is isotope analysis. At present, the state-of-the-art methodology for obtaining isotopic distributions is thermal ionization mass spectrometry (TIMS). Although TIMS is highly accurate at determining isotope distributions, the technique requires an elementally pure sample to perform the measurement. The required radiochemical separations give rise to sample preparation times that can be in excess of one to two weeks. Clearly, the nuclear forensics community is in need of instrumentation and methods that can expedite their decision making process in the event of a radiological release or nuclear detonation. Accordingly, we are developing instrumentation that couples a high resolution IM drift cell to the front end of a MS. The IM cell provides a means of separating ions based upon their collision cross-section and mass-to-charge ratio (m/z). Two analytes with the same m/z, but with different collision cross-sections (shapes) would exit the cell at different times, essentially enabling the cell to function in a similar manner to a gas chromatography (GC) column. Thus, molecular and atomic isobaric interferences can be effectively removed from the ion beam. The mobility selected chemical species could then be introduced to a MS for high-resolution mass analysis to generate isotopic distributions of the target analytes. The outcome would be an IM/MS system capable of accurately measuring isotopic distributions while concurrently eliminating isobaric interferences and laboratory radiochemical sample preparation. The overall objective of this project is developing instrumentation and methods to produce near real-time isotope distributions with a modular mass spectrometric system that performs the required gas-phase chemistry and

Isotope separation process

International Nuclear Information System (INIS)

Wexler, Sol; Young, C.E.

1976-01-01

Description is given of method for separating a specific isotope from a mixture of isotopes of an actinide element present as MF 6 , wherein M is the actinide element. It comprises: preparing a feed gas mixture of MF 6 in a propellant gas; passing the feed gas mixture under pressure through an expansion nozzle while heating the mixture to about 600 0 C; releasing the heated gas mixture from the nozzle into an exhaust chamber having a reduced pressure, whereby a gas jet of MF 6 molecules, MF 6 molecular clusters and propellant gas molecules is formed, the MF 6 molecules having a translational energy of about 3 eV; converting the MF 6 molecules to MF 6 ions by passing the jet through a cross jet of electron donor atoms so that an electron transfer takes place between the MF 6 - molecules and the electron donor atoms whereby the jet is now quasi-neutral, containing negative MF 6 - ions and positive donor ions; passing the quasi-neutral jet through a radiofrequency mass filter tuned to separate the MF 6 ions containing the specific isotope from the MF 6 - ions of the other isotopes and neutralizing and collecting the MF 6 molecules of the specific isotope [fr

Production yields of noble-gas isotopes from ISOLDE UC$_{x}$/graphite targets

CERN Document Server

Bergmann, U C; Catherall, R; Cederkäll, J; Diget, C A; Fraile-Prieto, L M; Franchoo, S; Fynbo, H O U; Gausemel, H; Georg, U; Giles, T; Hagebø, E; Jeppesen, H B; Jonsson, O C; Köster, U; Lettry, Jacques; Nilsson, T; Peräjärvi, K; Ravn, H L; Riisager, K; Weissman, L; Äystö, J

2003-01-01

Yields of He, Ne, Ar, Kr and Xe isotopic chains were measured from UC$_{x}$/graphite and ThC$_{x}$/graphite targets at the PSB-ISOLDE facility at CERN using isobaric selectivity achieved by the combination of a plasma-discharge ion source with a water-cooled transfer line. %The measured half-lives allowed %to calculate the decay losses of neutron-rich isotopes in the %target and ion-source system, and thus to obtain information on the in-target %productions from the measured yields. The delay times measured for a UC$_x$/graphite target allow for an extrapolation to the expected yields of very neutron-rich noble gas isotopes, in particular for the ``NuPECC reference elements'' Ar and Kr, at the next-generation radioactive ion-beam facility EURISOL. \\end{abstract} \\begin{keyword} % keywords here, in the form: keyword \\sep keyword radioactive ion beams \\sep release \\sep ion yields \\sep ISOL (Isotope Separation On-Line) \\sep uranium and thorium carbide targets. % PACS codes here, in the form: \\PACS code \\sep code...

Chiral gas chromatography for the determination of 1,2-O-isopropylidene-sn-glycerol stereoisomers

NARCIS (Netherlands)

Dröge, M.J; Bos, R.; Woerdenbag, H.J.; Quax, Wim; Droge, MJ

2003-01-01

A stereospecific gas chromatography (GC) method using a (6-O-tButyldimethylsilyl-2,3-di-O-methyl)-beta-cyclodextrin as the chiral stationary phase has been developed and validated for the determination of the enantiomers of 1,2-O-isopropylidene-sn-glycerol (IPG), an important chiral synthon, in

Quantification of residual solvents in antibody drug conjugates using gas chromatography

Energy Technology Data Exchange (ETDEWEB)

Medley, Colin D., E-mail: medley.colin@gene.com [Genentech Inc., Small Molecule Pharmaceutical Sciences, 1 DNA Way, South San Francisco, CA 94080 (United States); Kay, Jacob [Research Pharmaceutical Services, 520 Virginia Dr. Fort, Washington, PA (United States); Li, Yi; Gruenhagen, Jason; Yehl, Peter; Chetwyn, Nik P. [Genentech Inc., Small Molecule Pharmaceutical Sciences, 1 DNA Way, South San Francisco, CA 94080 (United States)

2014-11-19

Highlights: • Sensitive residual solvents detection in ADCs. • 125 ppm QL for common conjugation solvents. • Generic and validatable method. - Abstract: The detection and quantification of residual solvents present in clinical and commercial pharmaceutical products is necessary from both patient safety and regulatory perspectives. Head-space gas chromatography is routinely used for quantitation of residual solvents for small molecule APIs produced through synthetic processes; however residual solvent analysis is generally not needed for protein based pharmaceuticals produced through cultured cell lines where solvents are not introduced. In contrast, antibody drug conjugates and other protein conjugates where a drug or other molecule is covalently bound to a protein typically use solvents such as N,N-dimethylacetamide (DMA), N,N‑dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or propylene glycol (PG) to dissolve the hydrophobic small molecule drug for conjugation to the protein. The levels of the solvent remaining following the conjugation step are therefore important to patient safety as these parental drug products are introduced directly into the patients bloodstream. We have developed a rapid sample preparation followed by a gas chromatography separation for the detection and quantification of several solvents typically used in these conjugation reactions. This generic method has been validated and can be easily implemented for use in quality control testing for clinical or commercial bioconjugated products.

Basic methods of isotope analysis

International Nuclear Information System (INIS)

Ochkin, A.V.; Rozenkevich, M.B.

2000-01-01

The bases of the most applied methods of the isotope analysis are briefly presented. The possibilities and analytical characteristics of the mass-spectrometric, spectral, radiochemical and special methods of the isotope analysis, including application of the magnetic resonance, chromatography and refractometry, are considered [ru

Identification of chemical components in Baidianling Capsule based on gas chromatography-mass spectrometry and high-performance liquid chromatography combined with Fourier transform ion cyclotron resonance mass spectrometry.

Science.gov (United States)

Wu, Wenying; Chen, Yu; Wang, Binjie; Sun, Xiaoyang; Guo, Ping; Chen, Xiaohui

2017-08-01

Baidianling Capsule, which is made from 16 Chinese herbs, has been widely used for treating vitiligo clinically. In this study, the sensitive and rapid method has been developed for the analysis of chemical components in Baidianling Capsule by gas chromatography-mass spectrometry in combination with retention indices and high-performance liquid chromatography combined with Fourier transform ion cyclotron resonance mass spectrometry. Firstly, a total of 110 potential volatile compounds obtained from different extraction procedures including alkanes, alkenes, alkynes, ketones, ethers, aldehydes, alcohols, phenols, organic acids, esters, furans, pyrrole, acid amides, heterocycles, and oxides were detected from Baidianling Capsule by gas chromatography-mass spectrometry, of which 75 were identified by mass spectrometry in combination with the retention index. Then, a total of 124 components were tentatively identified by high-performance liquid chromatography combined with Fourier transform ion cyclotron resonance mass spectrometry. Fifteen constituents from Baidianling Capsule were accurately identified by comparing the retention times with those of reference compounds, others were identified by comparing the retention times and mass spectrometry data, as well as retrieving the reference literature. This study provides a practical strategy for rapidly screening and identifying the multiple constituents of a complex traditional Chinese medicine. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pots and lipids: molecular and isotope evidence of the food processing at Maharski prekop

Directory of Open Access Journals (Sweden)

Nives Ogrinc

2012-12-01

Full Text Available The pottery assemblage from the Maharski prekop site was analysed to obtain insights into vessel use and husbandry practices. Total lipid extracts of pottery samples were subjected to gas chromatography (GC, gas chromatography–mass spectrometry (GC–MS, gas chromatography–combustion–isotope ratio mass spectrometry (GC–C–IRMS and soft ionisation electrospray mass spectrometric techniques ESI Q–TOF MS and ESI Q–TOF MS/MS. The charred organic deposits on vessels were AMS 14C dated. The results show that some vessels were used for cooking ruminant meat, while in other traces of mixed non–ruminant and ruminant meat or plants and animal meat cooking were identified. Some vessels were used for milk processing.

Use of stable isotopes to monitor the natural attenuation of dicyclopentadiene

International Nuclear Information System (INIS)

Stehemier, L.G.; Cooke, L.; Hornett, R.; Aravena, R.

2002-01-01

Stable isotope fractionation is a method used to prove that residual hydrocarbons from an oil spill are being naturally attenuated in soil and groundwater. Hydrogen isotopes and carbon isotopes are the two isotopes that have been used to provide this evidence. Evaporation, adsorption and biodegradation are among the processes that can cause fractionation of isotopes. However, the largest fractionations take place during biodegradation because of the unidirectional characteristics of metabolism and the thermodynamic selectivity of enzymatic processes in biological systems. This paper presents the results of a monitored natural attenuation program for hydrocarbons in soil and groundwater at a chemical plant in Alberta where dicyclopentadiene (DCPD) was biodegraded. DCPD is a co-product from the cracking of ethane to ethylene. Piezometers were used to monitor the stable isotope fractionation of DCPD over a three year period. Evidence that DCPD was biodegrading was the fact that the change in carbon 13 was enriched 4.1 per cent in one study area during the monitoring period. The results are among the first definitive proof that DCPD biodegrades in the field. Analysis by gas chromatography-carbon-isotope ratio mass spectrometry is an essential technique for monitoring recalcitrant, low water-soluble hydrocarbons. 16 refs., 4 tabs., 3 figs

Complementary stable carbon isotope ratio and amount of substance measurements in sports anti-doping.

Science.gov (United States)

Cawley, Adam T; George, Adrian V

2012-12-01

The detection of steroids originating from synthetic precursors against a background of their chemically identical natural analogues has proven to be a significant challenge for doping control laboratories accredited by the World Anti-Doping Agency (WADA). The complementary application of gas chromatography-mass spectrometry (GC-MS) and gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) has been demonstrated to provide specific detection of endogenous steroid misuse for improved anti-doping analysis. Markers of synthetically derived steroids are reviewed on the basis of abnormal urinary excretions and low (13)C content. A combinatorial approach is presented for the interpretation of GC-MS and GC-C-IRMS data in the anti-doping context. This methodology can allow all relevant information concerning an individual's metabolism to be assessed in order to make an informed decision with respect to a doping violation. Copyright © 2012 John Wiley & Sons, Ltd.

Application of Stable Isotope-Assisted Metabolomics for Cell Metabolism Studies

Science.gov (United States)

You, Le; Zhang, Baichen; Tang, Yinjie J.

2014-01-01

The applications of stable isotopes in metabolomics have facilitated the study of cell metabolisms. Stable isotope-assisted metabolomics requires: (1) properly designed tracer experiments; (2) stringent sampling and quenching protocols to minimize isotopic alternations; (3) efficient metabolite separations; (4) high resolution mass spectrometry to resolve overlapping peaks and background noises; and (5) data analysis methods and databases to decipher isotopic clusters over a broad m/z range (mass-to-charge ratio). This paper overviews mass spectrometry based techniques for precise determination of metabolites and their isotopologues. It also discusses applications of isotopic approaches to track substrate utilization, identify unknown metabolites and their chemical formulas, measure metabolite concentrations, determine putative metabolic pathways, and investigate microbial community populations and their carbon assimilation patterns. In addition, 13C-metabolite fingerprinting and metabolic models can be integrated to quantify carbon fluxes (enzyme reaction rates). The fluxome, in combination with other “omics” analyses, may give systems-level insights into regulatory mechanisms underlying gene functions. More importantly, 13C-tracer experiments significantly improve the potential of low-resolution gas chromatography-mass spectrometry (GC-MS) for broad-scope metabolism studies. We foresee the isotope-assisted metabolomics to be an indispensable tool in industrial biotechnology, environmental microbiology, and medical research. PMID:24957020

Screening for estrogen residues in calf urine: Comparison of a validated yeast estrogen bioassay and gas chromatography-tandem mass spectrometry

NARCIS (Netherlands)

Nielen, M.W.F.; Bovee, T.F.H.; Heskamp, H.H.; Lasaroms, J.J.P.; Sanders, M.B.; Rhijn, van J.A.; Groot, M.J.; Hoogenboom, L.A.P.

2006-01-01

Within the European Union, the control for residues of illegal hormones in food-producing animals is based on urine analysis for a few target analytes using gas chromatography/mass spectrometry and/or liquid chromatography¿tandem mass spectrometry. Recently, we developed a robust yeast bioassay

Gas phase chromatography of halides of elements 104 and 105

International Nuclear Information System (INIS)

Tuerler, A.; Gregorich, K.E.; Czerwinski, K.R.; Hannink, N.J.; Henderson, R.A.; Hoffman, D.C.; Kacher, C.D.; Kadkhodayan, B.; Kreek, S.A.; Lee, D.M.; Leyba, J.D.; Nurmia, M.J.; Gaeggeler, H.W.; Jost, D.T.; Kovacs, J.; Scherer, U.W.; Vermeulen, D.; Weber, A.; Barth, H.; Gober, M.K.; Kratz, J.V.; Bruechle, W.; Schaedel, M.; Schimpf, E.; Gober, M.K.; Kratz, J.V.; Zimmermann, H.P.

1991-04-01

On-line isothermal gas phase chromatography was used to study halides of 261 104 (T 1/2 = 65 s) and 262,263 105 (T 1/2 = 34 s and 27 s) produced an atom-at-a time via the reactions 248 Cm( 18 O, 5n) and 249 Bk( 18 O, 5n, 4n), respectively. Using HBr and HCl gas as halogenating agents, we were able to produce volatile bromides and chlorides of the above mentioned elements and study their behavior compared to their lighter homologs in Groups 4 or 5 of the periodic table. Element 104 formed more volatile bromides than its homolog Hf. In contrast, element 105 bromides were found to be less volatile than the bromides of the group 5 elements Nb and Ta. Both 104 and Hf chlorides were observed to be more volatile than their respective bromides. 31 refs., 8 figs

Profiling of volatile organic compounds produced by clinical Aspergillus isolates using gas chromatography-mass spectrometry

NARCIS (Netherlands)

Gerritsen, M G; Brinkman, P; Escobar Salazar, Natalia; Bos, L D; de Heer, K; Meijer, M; Janssen, H-G; de Cock, H; Wösten, H A B; Visser, C.E.; van Oers, M H J; Sterk, P J

Volatile organic compounds (VOCs) in exhaled breath may identify the presence of invasive pulmonary aspergillosis. We aimed to detect VOC profiles emitted by in vitro cultured, clinical Aspergillus isolates using gas chromatography-mass spectrometry (GC-MS). Three clinical Aspergillus isolates and a

Monitoring the behaviour of 4-ketocyclophosphamide versus cyclophosphamide during capillary gas chromatography by mass spectrometry

NARCIS (Netherlands)

Bruijn, de E.A.; Oosterom, van A.T.; Leclercq, P.A.; Haan, de J.W.; Ven, van de L.J.M.; Tjaden, U.R.

1987-01-01

Capillary Gas Chromatography (CGC) is capable of determining underivatized cyclophosphamide (CPA) using SCOT OV 275 columns. Then CPA is subjected to in situ degradation resulting in formation of a cyclization product which can be determined selectively in biological fluids. In routine bioanalysis

Profiling of volatile organic compounds produced by clinical Aspergillus isolates using gas chromatography-mass spectrometry

NARCIS (Netherlands)

Gerritsen, M. G.; Brinkman, P.; Escobar, N.; Bos, L. D.; de Heer, K.; Meijer, M.; Janssen, H.-G.; de Cock, H.; Wösten, H. A. B.; Visser, C. E.; van Oers, M. H. J.; Sterk, P. J.

2018-01-01

Volatile organic compounds (VOCs) in exhaled breath may identify the presence of invasive pulmonary aspergillosis. We aimed to detect VOC profiles emitted by in vitro cultured, clinical Aspergillus isolates using gas chromatography-mass spectrometry (GC-MS). Three clinical Aspergillus isolates and a

Investigation of parameters affecting the online combination of supercritical fluid extraction with capillary gas chromatography

NARCIS (Netherlands)

Lou, X.W.; Janssen, J.G.M.; Cramers, C.A.M.G.

1996-01-01

Two different injectors, a split/splitless injector and a programmed temperature vaporizer (PTV) injector were investigated as the interface in on-line supercritical fluid extraction (SFE)-capillary gas chromatography (cGC). The parameters affecting the chromatographic peak shapes as well as the

Gas chromatography-mass spectrometry and high-performance liquid chromatography-diode array detection for dating of paper ink.

Science.gov (United States)

Díaz-Santana, Oscar; Vega-Moreno, Daura; Conde-Hardisson, Francisco

2017-09-15

An extraction and determination method is shown for the analysis of dyes and solvents present in two types of ballpoint pen inks that are deposited onto paper. Ink extracts are analysed using a combination of gas chromatography with mass spectrometry (GC-MS), and high-pressure liquid chromatography with photodiode array detection (HPLC-DAD), within a single sample extraction procedure. Seventeen solvents and thirteen dyes contained in two Montblanc ® inks (black and blue) were monitored for 45 months at monthly intervals, in order to determine variations in the concentrations of the compounds over time. We also studied the relative variations between different compounds and the generation of degradation products such as phenol. The concentration data obtained from these compounds during their exposure have been analysed and a multiple regression model is developed for each ink type that allows an estimate of the exposure time of the ink on paper with a maximum error of between 4 and 7 months. Copyright © 2017 Elsevier B.V. All rights reserved.

The distribution of helium isotopes of natural gas and tectonic environment

International Nuclear Information System (INIS)

Sun Mingliang; Tao Mingxin

1993-01-01

Based on the 3 He/ 4 He data of the main oil-gas bearing basins in continental China, a systematic study has been made for the first time on the relations between the space distribution of the helium isotopes of natural gas and the tectonic environment. The average value R-bar of 3 He/ 4 He in eastern China bordering on the Pacific Ocean is 2.08 x 10 -6 >Ra, and that is dualistic mixed helium containing mantle source helium. The R-bar of central and western China is 4.96 x 10 -8 , and that is mainly crust source radioactive helium. The R-bar of Huabei and Zhongyuan oil-gas fields is 8.00 x 10 -7 , and that is a kind of transitional helium intercepted between the eastern region and the central western region of China. On the whole, the 3 He/ 4 He values decrease gradually with the distance from the subduction zone of the Western Pacific Ocean. The results show that the space distributions of the helium isotopes is controlled by the tectonic environment, that is the environment of tensile rift, especially in the neighborhood of deep megafractures advantageous to the rise of mantle source helium, so then and there the 3 He/ 4 He value is the highest; In the most stable craton basins, the value is the lowest and the helium is a typical crust source radioactive one. Between the active area (rift) and stable area, there is the transitional helium and its value is 10 -7 , as is the case in Huabei-Zhongyuan oil-gas field

The influence of carrier gas flow rate in inverse gas chromatography on the estimation of water vapor adsorption on Nylon-6 micro fiber

OpenAIRE

丸井, 正樹; 山本, 直子; 牛腸, ヒロミ; マルイ, マサキ; ヤマモト, ナオコ; ゴチョウ, ヒロミ; MASAKI, MARUI; NAOKO, YAMAMOTO; HIROMI, GOCHO

2002-01-01

The adsorption behaviors of water vapor on Nylon-6 micro fiber are measured at 90℃ with inverse gas chromatography, of which the carrier gas flow rates are 10～40ml/min. The values of retention volume decrease when the peak area is on the increase. lt indicates that Nylon-6 micro fiber has strong adsorption of water vapor at low vapor pressure. The adsorption isotherm as a whole is found to be of BET II type with certain number of adsorption sites. The gas flow rate has no effect on the estima...

Authenticity assessment of gamma- and delta-decalactone from prunus fruits by gas chromatography combustion/pyrolysis isotope ratio mass spectrometry (GC-C/P-IRMS).

Science.gov (United States)

Tamura, Hirotoshi; Appel, Markus; Richling, Elke; Schreier, Peter

2005-06-29

Authenticity assessment of gamma-decalactone (1) and delta-decalactone (2) from peach (Prunus persica var. persica), apricot (Prunus armeniaca), and nectarine (Prunus persica var. nectarina) was performed using gas chromatography-isotope ratio mass spectrometry (GC-IRMS) in the combustion (C) and pyrolysis (P) mode. In addition, commercially available synthetic (nature-identical) 1 and 2 as well as biotechnologically produced samples (declared to be "natural") were characterized by their delta(2)H(V)(-)(SMOW) and delta(13)C(V)(-)(PDB) values. For the Prunus fruits under study, rather narrow ranges of delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW) data of 1, varying from - 34.6 per thousand to - 38.4 per thousand and -160 per thousand to -206 per thousand, respectively, were obtained. Synthetic references of 1 showed delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW) data ranging from -27.4 per thousand to -28.3 per thousand and -151 per thousand to -184 per thousand, respectively. Samples of 1 declared to be "natural" exhibited ranges from -28.1 per thousand to -29.2 per thousand and -192 per thousand to -286 per thousand for delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW), respectively. For 2 from peach, apricot, and nectarine, delta(13)C(V)(-)(PDB) values ranging from -34.0 per thousand to -37.9 per thousand were determined; the delta(2)H(V)(-)(SMOW) values ranged from -171 per thousand to -228 per thousand. The delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW) data for synthetic 2 were -28.2 per thousand and -171 per thousand, respectively, that is, similar to those of 2 from "natural" origin, ranging from -27.7 per thousand to -30.1 per thousand and -185 per thousand to -230 per thousand for delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW), respectively. GC-C/P-IRMS allowed clear-cut analytical differentiation of the synthetic and "ex-plant" origin of 1 and 2, whereas narrow ranges of delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW) data were found for samples of

Hyphenated and comprehensive liquid chromatography × gas chromatography-mass spectrometry for the identification of Mycobacterium tuberculosis.

Science.gov (United States)

Mourão, Marta P B; Denekamp, Ilse; Kuijper, Sjoukje; Kolk, Arend H J; Janssen, Hans-Gerd

2016-03-25

Tuberculosis is one of the world's most emerging public health problems, particularly in developing countries. Chromatography based methods have been used to tackle this epidemic by focusing on biomarker detection. Unfortunately, interferences from lipids in the sputum matrix, particularly cholesterol, adversely affect the identification and detection of the marker compounds. The present contribution describes the serial combination of normal phase liquid chromatography (NPLC) with thermally assisted hydrolysis and methylation followed by gas chromatography-mass spectrometry (THM-GC-MS) to overcome the difficulties of biomarker evaluation. The in-series combination consists of an LC analysis where fractions are collected and then transferred to the THM-GC-MS system. This was either done with comprehensive coupling, transferring all the fractions, or with hyphenated interfacing, i.e. off-line multi heart-cutting, transferring only selected fractions. Owing to the high sensitivity and selectivity of LC as a sample pre-treatment method, and to the high specificity of the MS as a detector, this analytical approach, NPLC × THM-GC-MS, is extremely sensitive. The results obtained indicate that this analytical set-up is able to detect down to 1 × 10(3) mycobacteria/mL of Mycobacterium tuberculosis strain 124, spiked in blank sputum samples. It is a powerful analytical tool and also has great potential for full automation. If further studies demonstrate its usefulness when applied blind in real sputum specimens, this technique could compete with the current smear microscopy in the early diagnosis of tuberculosis. Copyright © 2015 Elsevier B.V. All rights reserved.

Continuous determination of volatile products in anaerobic fermenters by on-line capillary gas chromatography

International Nuclear Information System (INIS)

Diamantis, V.; Melidis, P.; Aivasidis, A.

2006-01-01

Bio-ethanol and biogas produced during the anaerobic conversion of organic compounds has been a subject of great interest since the oil crisis of the 1970s. In ethanol fermentation and anaerobic treatment of wastewaters, end-product (ethanol) and intermediate-products (short-chain fatty acids, SCFA) cause inhibition that results in reduced process efficiency. Control of these constituents is of utmost importance for bioreactor optimization and process stability. Ethanol and SCFA can be detected with precision by capillary gas chromatography usually conducted in off-line measurements. In this work, an on-line monitoring and controlling system was developed and connected to the fermenter via an auto-sampling equipment, which could perform the feeding, filtration and dilution of the sample and final injection into the gas chromatograph through an automation-based programmed procedure. The sample was continuously pumped from the recycle stream of the bioreactor and treated using a microfiltration unit. The concentrate was returned to the reactor while the permeate was quantitatively mixed with an internal standard solution. The system comprised of a gas chromatograph with the flow cell and one-shot sampler and a PC with the appropriate software. The on-line measurement of ethanol and SCFA, directly from the liquid phase of an ethanol fermenter and a high-rate continuous mode anaerobic digester, was accomplished by gas chromatography. Also, this monitoring and controlling system was proved to be effective in the continuous fermentation of alcohol-free beer

Dosage direct des alcools dans les carburols par chromatographie en phase gazeuse Direct Gas Chromatographie Determination of Alcohols in Gasolines Blended by Oxygenated Compounds

Directory of Open Access Journals (Sweden)

Petroff N.

2006-11-01

Full Text Available Dans cette étude, on décrit une méthode de chromatographie en phase gazeuse utilisant une colonne remplie ; elle permet de doser, sans préfractionnement, les alcools jusqu'aux butanols dans les carburols (carburants additionnés de composés oxygénés. La phase stationnaire sélectionnée est le glycérol. This report describes a gas chromatographie method using a packed column. It allows the direct determination of alcohols up to butanols in gasolines blended with oxygenated compounds without prefractionation. Glycerol has been selected as stationary phase.

Analysis of artificial fireplace logs by high temperature gas chromatography.

Science.gov (United States)

Kuk, Raymond J

2002-11-01

High temperature gas chromatography is used to analyze the wax of artificial fireplace logs (firelogs). Firelogs from several different manufacturers are studied and compared. This study shows that the wax within a single firelog is homogeneous and that the wax is also uniform throughout a multi-firelog package. Different brands are shown to have different wax compositions. Firelogs of the same brand, but purchased in different locations, also have different wax compositions. With this information it may be possible to associate an unknown firelog sample to a known sample, but a definitive statement of the origin cannot be made.

Abundances of light isotopes in galactic cosmic rays and the interstellar gas density

International Nuclear Information System (INIS)

Westergaard, N.J.

1979-01-01

The fluxes of the light isotopes in the galactic cosmic rays are calculated in the energy range from 10 MeV to 5 GeV. The mean amount of matter traversed is taken to increase with decreasing energy, and various forms of the source spectrum are assumed. It is shown that it is possible to reconcile all observed abundance ratios including the low 10 Be abundance found by Garcia-Munoz et al. with an interstellar gas density of 1 atom cm -1 . However, a low value for the adiabatic deceleration in the solor cavity must be assumed. Comparing isotopes of the light elements does not give a unique solution for the deceleration, and it seems to be more profitable to use the isotopes of H and He for this purpose

pH-dependent equilibrium isotope fractionation associated with the compound specific nitrogen and carbon isotope analysis of substituted anilines by SPME-GC/IRMS.

Science.gov (United States)

Skarpeli-Liati, Marita; Turgeon, Aurora; Garr, Ashley N; Arnold, William A; Cramer, Christopher J; Hofstetter, Thomas B

2011-03-01

Solid-phase microextraction (SPME) coupled to gas chromatography/isotope ratio mass spectrometry (GC/IRMS) was used to elucidate the effects of N-atom protonation on the analysis of N and C isotope signatures of selected aromatic amines. Precise and accurate isotope ratios were measured using polydimethylsiloxane/divinylbenzene (PDMS/DVB) as the SPME fiber material at solution pH-values that exceeded the pK(a) of the substituted aniline's conjugate acid by two pH-units. Deviations of δ(15)N and δ(13)C-values from reference measurements by elemental analyzer IRMS were small (IRMS. Under these conditions, the detection limits for accurate isotope ratio measurements were between 0.64 and 2.1 mg L(-1) for δ(15)N and between 0.13 and 0.54 mg L(-1) for δ(13)C, respectively. Substantial inverse N isotope fractionation was observed by SPME-GC/IRMS as the fraction of protonated species increased with decreasing pH leading to deviations of -20‰ while the corresponding δ(13)C-values were largely invariant. From isotope ratio analysis at different solution pHs and theoretical calculations by density functional theory, we derived equilibrium isotope effects, EIEs, pertinent to aromatic amine protonation of 0.980 and 1.001 for N and C, respectively, which were very similar for all compounds investigated. Our work shows that N-atom protonation can compromise accurate compound-specific N isotope analysis of aromatic amines.

Estimation of brassylic acid by gas chromatography-mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

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.

Assessment of diffusive isotopic fractionation in polar firn, and application to ice core trace gas records

DEFF Research Database (Denmark)

Buizert, C.; Sowers, T.; Blunier, T.

2013-01-01

During rapid variations of the atmospheric mixing ratio of a trace gas, diffusive transport in the porous firn layer atop ice sheets and glaciers alters the isotopic composition of that gas relative to the overlying atmosphere. Records of past atmospheric trace gas isotopic composition from ice...... cores and firn need to be corrected for this diffusive fractionation artifact. We present a novel, semi-empirical method to accurately estimate the magnitude of the diffusive fractionation in the ice core record. Our method (1) consists of a relatively simple analytical calculation; (2) requires only...... commonly available ice core data; (3) is not subject to the uncertainties inherent to estimating the accumulation rate, temperature, close-off depth and depth-diffusivity relationship back in time; (4) does not require knowledge of the true atmospheric variations, but uses the smoothed records obtained...

Method development and validation for the determination of pesticides in green coffee by gas chromatography

International Nuclear Information System (INIS)

Dallos Corredor, David; Guerrero Dallos, Jairo Arturo

2005-01-01

This study describes the implementation and validation of a multiresidue methodology for the determination of organochlorine, organophosphorus and pyrethroids pesticides in green coffee. Pesticides residues were extracted from green samples with an acetone-water (2:1) mixture followed by ethyl acetate cyclohexane (1:1) partitioning. The clean up steps include gel permeation chromatography and mini column chromatography using silica gel. Final determination was carried out by high-resolution gas chromatography with a pulsed split less injection mode and simultaneous detection by μ-ECD and NPD coupled in parallel. The methodology is specific, selective precise and accurate. Recoveries of majority of pesticides from spiked samples range from 70 to 110% at fortification levels of 0.038 mg/kg-1.536 mg/kg with limit of quantitation between 0.011 mg/kg and 0.100 mg/kg

Determination of ketone bodies in blood by headspace gas chromatography-mass spectrometry

DEFF Research Database (Denmark)

Holm, Karen Marie Dollerup; Linnet, Kristian; Rasmussen, Brian Schou

2010-01-01

A gas chromatography-mass spectrometry (GC-MS) method for determination of ketone bodies (ß-hydroxybutyrate, acetone, and acetoacetate) in blood is presented. The method is based on enzymatic oxidation of D-ß-hydroxybutyrate to acetoacetate, followed by decarboxylation to acetone, which...... was quantified by the use of headspace GC-MS using acetone-(13)C(3) as an internal standard. The developed method was found to have intra- and total interday relative standard deviations

Cortisol production rates measured by liquid chromatography/mass spectrometry

International Nuclear Information System (INIS)

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

1990-01-01

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

A protocol for pressurized liquid extraction and processing methods to isolate modern and ancient bone cholesterol for compound-specific stable isotope analysis.

Science.gov (United States)

Laffey, Ann O; Krigbaum, John; Zimmerman, Andrew R

2017-02-15

Bone lipid compound-specific isotope analysis (CSIA) and bone collagen and apatite stable isotope ratio analysis are important sources of ecological and paleodietary information. Pressurized liquid extraction (PLE) is quicker and utilizes less solvent than traditional methods of lipid extraction such as soxhlet and ultrasonication. This study facilitates dietary analysis by optimizing and testing a standardized methodology for PLE of bone cholesterol. Modern and archaeological bones were extracted by PLE using varied temperatures, solvent solutions, and sample weights. The efficiency of PLE was assessed via quantification of cholesterol yields. Stable isotopic ratio integrity was evaluated by comparing isotopic signatures (δ 13 C and δ 18 O values) of cholesterol derived from whole bone, bone collagen and bone apatite. Gas chromatography/mass spectrometry (GC/MS) and gas chromatography isotope ratio mass spectrometry (GC/IRMS) were conducted on purified collagen and lipid extracts to assess isotopic responses to PLE. Lipid yield was optimized at two PLE extraction cycles of 75 °C using dichloromethane/methanol (2:1 v/v) as a solvent with 0.25-0.75 g bone sample. Following lipid extraction, saponification combined with the derivatization of the neutral fraction using trimethylsilylation yielded nearly twice the cholesterol of non-saponified or non-derivatized samples. It was also found that lipids extracted from purified bone collagen and apatite could be used for cholesterol CSIA. There was no difference in the bulk δ 13 C values of collagen extracted from bone with or without lipid. However, there was a significant depletion in 18 O of bone apatite due to lipid presence or processing. These results should assist sample selection and provide an effective, alternative extraction method for bone cholesterol that may be used for isotopic and paleodietary analysis. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

气相色谱氩、氪、氙、氡分离度初步研究%Resolutions on Mixture of Argon, Krypton, Xenon and Radon by Gas Chromatography

Institute of Scientific and Technical Information of China (English)

刘蜀疆; 陈占营; 常印忠; 王世联; 李奇; 石建芳; 樊元庆; 赵允刚

2012-01-01

核爆炸产生多种稀有气体核素,这些核素可作为核泄露监测对象.气相色谱是组分分离的重要手段,在核爆炸监测取样中有重要应用.本文以5A分子筛作为固定相,高纯氮作为流动相,测量了氩、氪、氙、氡在气相色谱中的分离效果.结果表明,在相同色谱条件下,氩、氪分离度小于氪、氙分离度；在柱流量35.6 mL/min、柱温353 K条件下,气相色谱氩、氪,氪、氙,氙、氡分离度均大于2.25.%Radio-isotopes of noble gas, which are produced during nuclear explosion, can escape into atmosphere easily. These isotopes can be measured as good indicators for nuclear explosion. Noble gas monitoring, including sampling, measurement and analysis, became more and more essential. Gas chromatography is an important technology on noble gas separation during gas sampling. In this paper, while 5A molecular sieve was utilized as column stationary state and high-purity nitrogen as column fluid state, resolutions of argon, krypton, xenon and radon were widely investigated under different chromatograph conditions. As a result, the resolution of krypton and argon is less than the resolution of xenon and krypton; when column flow rate is 35. 6 mL/min and oven temperature is 353 K, all of the resolutions of radon and xenon, xenon and krypton, krypton and argon are more than 2. 25.

A gas extraction system for the measurement of carbon dioxide and carbon isotopes in polar ice cores

International Nuclear Information System (INIS)

Steig, E.

1992-06-01

Knowledge of the distribution of Carbon 13 in the glacial ocean, atmosphere, and biosphere is important to understanding the causes of glacial/interglacial changes in atmospheric CO 2 levels. Although deep-ocean Carbon 13 values are well-constrained by ocean sediment studies, model-based estimates of changes in the carbon budget for the biosphere and atmosphere vary considerably. Measurement of atmospheric Carbon 13 in CO 2 in ice cores will provide additional constraints on this budget and will also improve estimates of changes in the ocean surface layer Carbon 13. Direct measurement of ancient atmospheric Carbon 13 can be accomplished through polar ice core studies. A gas-extraction line for ice cores has been designed and constructed with particular attention to the specific difficulties of measuring Carbon 13 in CO 2 . The ice is shaved, rather than crushed, to minimize fractionation effects resulting from gas travel through long air-paths in the ice. To minimize the risk of isotopic contamination and fractionation within the vacuum line, CO 2 is separated immediately from the air; the CO 2 concentration is then measured by a simple pressure/volume comparison rather than by gas chromatography or spectroscopy. Measurements from Greenland ice core samples give an average value of 280±2 ppM CO 2 for preindustrial samples, demonstrating that the extraction system gives accurate, precise determinations Of CO 2 concentrations. Measurement of δ 13 C from polar ice samples has not been achieved at this time. However, results on standard air samples demonstrate a precision for δ 13 C of less than 0.2 per-thousand at the 95% confidence level

Isotope effect and isotope separation. A chemist's view

International Nuclear Information System (INIS)

Ishida, Takanobu

2002-01-01

What causes the isotope effects (IE)? This presentation will be centered around the equilibrium isotope effects due to the differences in the nuclear masses. The occurrence of the equilibrium constant, K, of isotope exchange reactions which differ from the values predicted by the classical theory of statistical mechanics, K cl , is explored. The non-classical K corresponds to the unit-stage separation factor, α, that is different from unity and forms a basis of an isotope separation process involving the chemical exchange reaction. Here, the word 'chemical exchange' includes not only the isotope exchange chemical reactions between two or more chemical species but also the isotope exchanges involving the equilibria between liquid and vapor phases and liquid-gas, liquid solution-gas, liquid-liquid, and solid-liquid phases. In Section I, origins of the isotope effect phenomena will be explored and, in the process, various quantities used in discussions of isotope effect that have often caused confusions will be unambiguously defined. This Section will also correlate equilibrium constant with separation factor. In Section II, various forms of temperature-dependence of IE and separation factor will be discussed. (author)

Gas chromatography/sniffing port analysis evaluated for aroma release from rehydrated French beans (Phaseolus vulgaris).

NARCIS (Netherlands)

Ruth, van S.M.; Roozen, J.P.; Cozijnsen, J.L.

1996-01-01

The technique of gas chromatography/sniffing port analysis was evaluated for studying the release of aroma compounds from rehydrated diced French beans. The aroma compounds 2-—methylbutanal and hexanal were released at a constant rate over time. An identical selection of odour active compounds was

The gas phase oxide and oxyhydroxide chemistry of trace amounts of rhenium

International Nuclear Information System (INIS)

Eichler, R.; Eichler, B.; Jost, D.T.; Dressler, R.; Tuerler, A.; Gaeggeler, H.W.

1999-01-01

In preparation of experiments to investigate the chemical properties of bohrium (Bh, element 107) the behaviour of Re, its lighter homologue in group 7, was studied in different oxidizing chemical systems. The adsorption data of Re oxide and oxyhydroxide compounds on quartz surfaces were evaluated from results of thermochromatography experiments and confirmed in isothermal gas chromatography experiments applying 1 cm as standard state for the simple gas adsorption process: X(g) ↔ X(ads) (X = ReO 3 , HReO 4 ) ΔH ads (ReO 3 ) = -190 ± 10 kJ/mol; ΔS ads (ReO 3 ) = -179±30 J/mol K; ΔH ads (HReO 4 ) = -77 ± 5 kJ/mol; ΔS ads (HReO 4 ) = -187±50 J/mol K. An on-line separation method for oxides and oxyhydroxides of short lived Re isotopes using isothermal high temperature gas-solid adsorption chromatography was developed. Separation yields and times of group 7 elements from lanthanides (model for actinides), polonium and bismuth were determined using the model isotopes 169,170,174,176 Re, 152-155 Er, 151-154 Ho, 218 Po, and 214 Bi. An updated correlation function between the microscopic adsorption enthalpy and the macroscopic sublimation enthalpy was calculated from the experimental adsorption data of this work and literature data. (orig.)

Identification and deconvolution of carbohydrates with gas chromatography-vacuum ultraviolet spectroscopy.

Science.gov (United States)

Schenk, Jamie; Nagy, Gabe; Pohl, Nicola L B; Leghissa, Allegra; Smuts, Jonathan; Schug, Kevin A

2017-09-01

Methodology for qualitative and quantitative determination of carbohydrates with gas chromatography coupled to vacuum ultraviolet detection (GC-VUV) is presented. Saccharides have been intently studied and are commonly analyzed by gas chromatography-mass spectrometry (GC-MS), but not always effectively. This can be attributed to their high degree of structural complexity: α/β anomers from their axial/equatorial hydroxyl group positioning at the C1-OH and flexible ring structures that lead to the open chain, five-membered ring furanose, and six-membered ring pyranose configurations. This complexity can result in convoluted chromatograms, ambiguous fragmentation patterns and, ultimately, analyte misidentification. In this study, mono-, di, and tri-saccharides were derivatized by two different methods-permethylation and oximation/pertrimethylsilylation-and analyzed by GC-VUV. These two derivatization methods were then compared for their efficiency, ease of use, and robustness. Permethylation proved to be a useful technique for the analysis of ketopentoses and pharmaceuticals soluble in dimethyl sulfoxide (DMSO), while the oximation/pertrimethylsilylation method prevailed as the more promising, overall, derivatization method. VUV spectra have been shown to be distinct and allow for efficient differentiation of isomeric species such as ketopentoses and reducing versus non-reducing sugars. In addition to identification, pharmaceutical samples containing several compounds were derivatized and analyzed for their sugar content with the GC-VUV technique to provide data for qualitative analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

Cross validation of gas chromatography-flame photometric detection and gas chromatography-mass spectrometry methods for measuring dialkylphosphate metabolites of organophosphate pesticides in human urine.

Science.gov (United States)

Prapamontol, Tippawan; Sutan, Kunrunya; Laoyang, Sompong; Hongsibsong, Surat; Lee, Grace; Yano, Yukiko; Hunter, Ronald Elton; Ryan, P Barry; Barr, Dana Boyd; Panuwet, Parinya

2014-01-01

We report two analytical methods for the measurement of dialkylphosphate (DAP) metabolites of organophosphate pesticides in human urine. These methods were independently developed/modified and implemented in two separate laboratories and cross validated. The aim was to develop simple, cost effective, and reliable methods that could use available resources and sample matrices in Thailand and the United States. While several methods already exist, we found that direct application of these methods required modification of sample preparation and chromatographic conditions to render accurate, reliable data. The problems encountered with existing methods were attributable to urinary matrix interferences, and differences in the pH of urine samples and reagents used during the extraction and derivatization processes. Thus, we provide information on key parameters that require attention during method modification and execution that affect the ruggedness of the methods. The methods presented here employ gas chromatography (GC) coupled with either flame photometric detection (FPD) or electron impact ionization-mass spectrometry (EI-MS) with isotopic dilution quantification. The limits of detection were reported from 0.10ng/mL urine to 2.5ng/mL urine (for GC-FPD), while the limits of quantification were reported from 0.25ng/mL urine to 2.5ng/mL urine (for GC-MS), for all six common DAP metabolites (i.e., dimethylphosphate, dimethylthiophosphate, dimethyldithiophosphate, diethylphosphate, diethylthiophosphate, and diethyldithiophosphate). Each method showed a relative recovery range of 94-119% (for GC-FPD) and 92-103% (for GC-MS), and relative standard deviations (RSD) of less than 20%. Cross-validation was performed on the same set of urine samples (n=46) collected from pregnant women residing in the agricultural areas of northern Thailand. The results from split sample analysis from both laboratories agreed well for each metabolite, suggesting that each method can produce

Measurement of natural carbon isotopic composition of acetone in human urine.

Science.gov (United States)

Yamada, Keita; Ohishi, Kazuki; Gilbert, Alexis; Akasaka, Mai; Yoshida, Naohiro; Yoshimura, Ryoko

2016-02-01

The natural carbon isotopic composition of acetone in urine was measured in healthy subjects using gas chromatography-combustion-isotope ratio mass spectrometry combined with headspace solid-phase microextraction (HS-SPME-GC-C-IRMS). Before applying the technique to a urine sample, we optimized the measurement conditions of HS-SPME-GC-C-IRMS using aqueous solutions of commercial acetone reagents. The optimization enabled us to determine the carbon isotopic compositions within ±0.2 ‰ of precision and ±0.3‰ of error using 0.05 or 0.2 mL of aqueous solutions with acetone concentrations of 0.3-121 mg/L. For several days, we monitored the carbon isotopic compositions and concentrations of acetone in urine from three subjects who lived a daily life with no restrictions. We also monitored one subject for 3 days including a fasting period of 24 h. These results suggest that changes in the availability of glucose in the liver are reflected in changes in the carbon isotopic compositions of urine acetone. Results demonstrate that carbon isotopic measurement of metabolites in human biological samples at natural abundance levels has great potential as a tool for detecting metabolic changes caused by changes in physiological states and disease.

Automatic isotope gas analysis of tritium labelled organic materials Pt. 3

International Nuclear Information System (INIS)

Gacs, I.; Mlinko, S.; Payer, K.; Otvos, L.; Banfi, D.; Palagyi, T.

1978-01-01

An isotope analytical procedure and an automatic instrument developed for the determination of tritium in organic compounds and biological materials by internal gas counting are described. The sample is burnt in a stream of oxygen and the combustion products including water vapour carrying the tritium are led onto a column of molecular sieve-5A heated to 550 deg C. Tritium is retained temporarily on the column, then transferred into a stream of hydrogen by isotope exchange. After addition of butane, the tritiated hydrogen is led into an internal detector and enclosed there for radioactivity measurement. The procedure, providing quantitative recovery, is completed in five minutes. It is free of memory effect and suitable for the determination of tritium in a wide range of organic compounds and samples of biological origin. (author)

37Cl/35Cl isotope ratio analysis in perchlorate by ion chromatography/multi collector -ICPMS: Analytical performance and implication for biodegradation studies.

Science.gov (United States)

Zakon, Yevgeni; Ronen, Zeev; Halicz, Ludwik; Gelman, Faina

2017-10-01

In the present study we propose a new analytical method for 37 Cl/ 35 Cl analysis in perchlorate by Ion Chromatography(IC) coupled to Multicollector Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS). The accuracy of the analytical method was validated by analysis of international perchlorate standard materials USGS-37 and USGS -38; analytical precision better than ±0.4‰ was achieved. 37 Cl/ 35 Cl isotope ratio analysis in perchlorate during laboratory biodegradation experiment with microbial cultures enriched from the contaminated soil in Israel resulted in isotope enrichment factor ε 37 Cl = -13.3 ± 1‰, which falls in the range reported previously for perchlorate biodegradation by pure microbial cultures. The proposed analytical method may significantly simplify the procedure for isotope analysis of perchlorate which is currently applied in environmental studies. Copyright © 2017. Published by Elsevier Ltd.

Carbon monoxide measurement by gas chromatography; Mesure du monoxyde de carbone par chromatographie en phase gazeuse

Energy Technology Data Exchange (ETDEWEB)

Gros, V.; Sarda-Esteve, R.; Bonsang, B.; Ramonet, M.

1998-09-01

Although carbon monoxide (CO) is present in trace quantities in the atmosphere (0.1 ppm -or parts per million in volume- on average), the study of this gas is important. Indeed, its impact on human can be dangerous at high level of concentration on the hand and it constitutes one of the main precursor of ozone in presence of concentration on the one hand and it constitutes one of the main precursor of ozone in presence of other pollutants on the other hand. Finally, CO affects the levels of several important greenhouse gases, through its reaction with hydroxyl radicals (OH). CO is measured in the atmosphere since the mid 60's by various methods. Among them, gas chromatography has the advantage to combine a low detection limit with a high precision. This report details the improvements made on the measurement analyser which allowed to perform automatic CO measurements in remote areas with low mixing ratios of carbon monoxide. This report describes some quality tests and the results of various applications. (authors)

Gas chromatography analysisof organic compounds labelled with 14C and T

International Nuclear Information System (INIS)