Science.gov

Sample records for gas chromatographic separation

  1. Fast gas chromatographic separation of biodiesel.

    SciTech Connect

    Pauls, R. E.

    2011-05-01

    A high-speed gas chromatographic method has been developed to determine the FAME distribution of B100 biodiesel. The capillary column used in this work has dimensions of 20 m x 0.100 mm and is coated with a polyethylene glycol film. Analysis times are typically on the order of 4-5 min depending upon the composition of the B100. The application of this method to a variety of vegetable and animal derived B100 is demonstrated. Quantitative results obtained with this method were in close agreement with those obtained by a more conventional approach on a 100 m column. The method, coupled with solid-phase extraction, was also found suitable to determine the B100 content of biodiesel-diesel blends.

  2. Gas chromatographic separation of methoxylated polychlorinated biphenyl atropisomers

    PubMed Central

    Kania-Korwel, Izabela; Vyas, Sandhya M.; Song, Yang; Lehmler, Hans-Joachim

    2008-01-01

    Several polychlorinated biphenyls (PCBs) and their hydroxylated metabolites display axial chirality. Here we describe an enantioselective, gas chromatographic separation of methylated derivatives of hydroxylated (OH-)PCB atropisomers (MeO-PCB) using a chemically bonded β-cyclodextrin column (Chirasil-Dex). The atropisomers of several MeO-PCBs could be separated on this column with resolutions ranging from 0.42–0.87 under isothermal or temperature-programmed conditions. In addition, the enantiomeric fraction of OH-PCB 136 metabolites was determined in male and female rats treated with racemic PCB 136. The methylated derivatives of two OH-PCB 136 metabolites showed an enantiomeric enrichment in liver tissue, whereas PCB 136 itself was near racemic. PMID:18760792

  3. Gas chromatographic separation of hydrogen isotopes using metal hydrides

    SciTech Connect

    Aldridge, F.T.

    1984-05-09

    A study was made of the properties of metal hydrides which may be suitable for use in chromatographic separation of hydrogen isotopes. Sixty-five alloys were measured, with the best having a hydrogen-deuterium separation factor of 1.35 at 60/sup 0/C. Chromatographic columns using these alloys produced deuterium enrichments of up to 3.6 in a single pass, using natural abundance hydrogen as starting material. 25 references, 16 figures, 4 tables.

  4. A Microporous Metal-Organic Framework for Gas Chromatographic Separation of Alkanes

    SciTech Connect

    Chen, Banglin; Liang, Chengdu; Yang, Jun; Contreras, Damacio; Clancy, Yvette; Lobkovsky, Emil B.; Yaghi, Omar; Dai, Sheng

    2006-01-01

    A zinc-based metal-organic framework (MOF) can be transformed reversibly from an open (a) to a dense (b) configuration. The microporous solid is the first example of a MOF that is highly selective in the gas-chromatographic separation of alkanes.

  5. Chromatographic hydrogen isotope separation

    DOEpatents

    Aldridge, F.T.

    Intermetallic compounds with the CaCu/sub 5/ type of crystal structure, particularly LaNiCo/sub 4/ and CaNi/sub 5/, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation column. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale multi-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen cn produce large quantities of heavy water at an effective cost for use in heavy water reactors.

  6. Chromatographic hydrogen isotope separation

    DOEpatents

    Aldridge, Frederick T.

    1981-01-01

    Intermetallic compounds with the CaCu.sub.5 type of crystal structure, particularly LaNiCo.sub.4 and CaNi.sub.5, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation colum. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale mutli-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen can produce large quantities of heavy water at an effective cost for use in heavy water reactors.

  7. Microminiature gas chromatograph

    DOEpatents

    Yu, C.M.

    1996-12-10

    A microminiature gas chromatograph ({mu}GC) comprising a least one silicon wafer, a gas injector, a column, and a detector. The gas injector has a normally closed valve for introducing a mobile phase including a sample gas in a carrier gas. The valve is fully disposed in the silicon wafer(s). The column is a microcapillary in silicon crystal with a stationary phase and is mechanically connected to receive the mobile phase from the gas injector for the molecular separation of compounds in the sample gas. The detector is mechanically connected to the column for the analysis of the separated compounds of sample gas with electronic means, e.g., ion cell, field emitter and PIN diode. 7 figs.

  8. Microminiature gas chromatograph

    DOEpatents

    Yu, Conrad M.

    1996-01-01

    A microminiature gas chromatograph (.mu.GC) comprising a least one silicon wafer, a gas injector, a column, and a detector. The gas injector has a normally closed valve for introducing a mobile phase including a sample gas in a carrier gas. The valve is fully disposed in the silicon wafer(s). The column is a microcapillary in silicon crystal with a stationary phase and is mechanically connected to receive the mobile phase from the gas injector for the molecular separation of compounds in the sample gas. The detector is mechanically connected to the column for the analysis of the separated compounds of sample gas with electronic means, e.g., ion cell, field emitter and PIN diode.

  9. Inlet backflushing device for the improvement of comprehensive two dimensional gas chromatographic separations.

    PubMed

    Edwards, Matthew; Górecki, Tadeusz

    2015-07-10

    Comprehensive two-dimensional gas chromatography (GC×GC) is recognised as a powerful tool for the separation of complex mixtures of volatile and semi-volatile compounds. In the analysis of challenging samples containing highly concentrated, active analytes or those with complicated matrices, it is often the case that less than ideal chromatography is produced. GC×GC chromatograms of such samples typically contain broad, tailing analyte bands. This results in difficulties with quantitation and poor utilisation of the separation space. In this study we investigated the inlet and the modulator as the potential sources of these tailing bands. A simple inlet backflushing device was developed to isolate the inlet from the primary column after the injection, and a similar setup was used to isolate the modulator from the primary column. The device allowed us to divert carrier gas flow back through the inlet at a specified time after the injection, while allowing analytes to pass through the column for separation. Analytes retained within the inlet were prevented from entering the column, and were subsequently removed via the carrier gas split line. The study revealed that the inlet plays a significant role in the development of tailing chromatographic bands, while the modulator simply modulates the already elongated band. Inlet backflushing is a cheap, simple and effective tool that can be used to improve the chromatography of problematic GC×GC analyses of samples consisting of concentrated and active analytes, those derived from natural products and containing complicated matrices. PMID:26028511

  10. Graphitic carbon nitride as high-resolution stationary phase for gas chromatographic separations.

    PubMed

    Zheng, Yunzhong; Qi, Meiling; Fu, Ruonong

    2016-07-01

    This work presents the first example of utilization of graphitic carbon nitride (g-C3N4) as stationary phase for capillary gas chromatographic (GC) separations. The statically coated g-C3N4 column showed the column efficiencies of 3760 plates/m and weak polarity. Its resolving capability and retention behaviours were investigated by using the Grob test mixture, and mixtures of diverse types of analytes, and structural and positional isomers. The results showed superior separation performance of the g-C3N4 stationary phase for some critical analytes and preferential retention for aromatic analytes. Specifically, it exhibited high-resolution capability for aromatic and aliphatic isomers such as methylnaphthalenes and dimethylnaphthalenes, phenanthrene and anthracene and alkane isomers. In addition, g-C3N4 column showed excellent thermal stability up to 280°C and good repeatability with relative standard deviation (RSD) values less than 0.09% for intra-day, below 0.23% for inter-day and in the range of 1.9-8.4% for between-column, respectively. The advantageous separation performance shows the potential of g-C3N4 and related materials as stationary phase in GC and other separation technologies. PMID:27266332

  11. Evaluation of two commercial capillary columns for the enantioselective gas chromatographic separation of organophosphorus pesticides.

    PubMed

    Fidalgo-Used, Natalia; Blanco-González, Elisa; Sanz-Medel, Alfredo

    2006-12-15

    The separation of the enantiomers of 13 organophosphorus pesticides (OPPs) has been investigated by gas chromatography (GC) with flame ionisation detection (FID) using two different commercially available chiral columns, Chirasil-Val (l-valine-tert-butylamide) and CP-Chirasil-Dex CB (heptakis (2,3,6-tri-O-metil)-beta-cyclodextrin). Using the Chirasil-Val column no chiral resolution was obtained for the OPPs investigated under any tested experimental condition. The use of the CP-Chirasil-Dex CB stationary phase enabled good individual enantiomeric separation of two OPPs, ruelene and trichlorfon and partial separation of naled, chloretoxyphos, isophenphos and metamidophos. Also, the obtained chromatographic results showed that Chirasil-Dex could resolve enantiomers through the combination of different mechanism (e.g. formation of inclusion complexes and/or interactions outside the cyclodextrin cavity). Under optimised conditions, precision, linearity range and detection limits were evaluated for the enantiomers of ruelene and trichlorfon using CP-Chirasil-Dex CB column and electron capture detection (ECD). By using the GC-ECD method the enantiomers of these OPPs could be satisfactorily detected at very low concentration levels. The detection limits observed were 1.5ngmL(-1) and 11.5ngmL(-1) for the enantiomers of trichlorfon and ruelene, respectively. PMID:18970881

  12. Deconvolution of gas chromatographic data

    NASA Technical Reports Server (NTRS)

    Howard, S.; Rayborn, G. H.

    1980-01-01

    The use of deconvolution methods on gas chromatographic data to obtain an accurate determination of the relative amounts of each material present by mathematically separating the merged peaks is discussed. Data were obtained on a gas chromatograph with a flame ionization detector. Chromatograms of five xylenes with differing degrees of separation were generated by varying the column temperature at selected rates. The merged peaks were then successfully separated by deconvolution. The concept of function continuation in the frequency domain was introduced in striving to reach the theoretical limit of accuracy, but proved to be only partially successful.

  13. Protecting Gas Chromatographic Syringes

    NASA Astrophysics Data System (ADS)

    Ruekberg, Ben

    1995-12-01

    This article describes the construction of a device which protects gas chromatographic syringes. The device lessens the likelihood of syringes rolling off tables and breaking. If the syringe is dropped, the glass barrel is less apt to be struck and shattered.

  14. Calix[4]pyrroles: highly selective stationary phases for gas chromatographic separations.

    PubMed

    Fan, Jing; Wang, Zhenzhong; Li, Qian; Qi, Meiling; Shao, Shijun; Fu, Ruonong

    2014-10-01

    Calix[4]pyrroles offer a great potential as stationary phases for gas chromatography (GC) due to their unique structures and physicochemical properties. Herein we present the first report of using two calix[4]pyrroles, namely meso-tetra-cyclohexylcalix[4]pyrrole (THCP) and meso-octamethylcalix[4]pyrrole (OMCP). These stationary phases were statically coated onto capillary columns and investigated in terms of column efficiency, polarity, separation performance, thermal stability and repeatability. The columns achieved column efficiencies of 2200-3000plates/m and exhibited nonpolar nature with an average polarity of 67 for THCP and 64 for OMCP, respectively. THCP stationary phase shows high selectivity for analytes of different polarity and exhibits nice peak shapes, especially for aldehydes, alcohols and anilines that are prone to severe peak tailing in GC analysis. Interestingly, THCP stationary phase possesses superior resolving ability for aniline and benzenediol positional isomers while OMCP shows preferential selectivity for nonpolar analytes such as hexane isomers. Moreover, calix[4]pyrrole columns also have good thermal stability up to 260°C and repeatability with a relative standard deviation (RSD%) of less than 0.10% for run-to-run and less than 5.2% for column-to-column. This work demonstrates the unique separation performance of calix[4]pyrroles and their promising future as a new class of GC stationary phases. PMID:25173993

  15. Comprehensive two-dimensional gas chromatographic separations with a temperature programmed microfabricated thermal modulator.

    PubMed

    Collin, William R; Nuñovero, Nicolas; Paul, Dibyadeep; Kurabayashi, Katsuo; Zellers, Edward T

    2016-04-29

    Comprehensive two-dimensional gas chromatography (GC×GC) with a temperature-programmed microfabricated thermal modulator (μTM) is demonstrated. The 0.78 cm(2), 2-stage μTM chip with integrated heaters and a PDMS coated microchannel was placed in thermal contact with a solid-state thermoelectric cooler and mounted on top of a bench scale GC. It was fluidically coupled through heated interconnects to an upstream first-dimension ((1)D) PDMS-coated capillary column and a downstream uncoated capillary or second-dimension ((2)D) PEG-coated capillary. A mixture of n-alkanes C6-C10 was separated isothermally and the full-width-at-half-maximum (fwhm) values of the modulated peaks were assessed as a function of the computer-controlled minimum and maximum stage temperatures of μTM, Tmin and Tmax, respectively. With Tmin and Tmax fixed at -25 and 100°C, respectively, modulated peaks of C6 and C7 had fwhm values<53 ms while the modulated peaks of C10 had a fwhm value of 1.3s, due to inefficient re-mobilization. With Tmin and Tmax fixed at 0 and 210°C, respectively, the fwhm value for the modulated C10 peaks decreased to 67 ms, but C6 and C7 exhibited massive breakthrough. By programming Tmin from -25 to 0°C and Tmax from 100 to 220°C, the C6 and C7 peaks had fwhm values≤50 ms, and the fwhm for C10 peaks remained<95 ms. Using the latter conditions for the GC×GC separation of a sample of unleaded gasoline yielded resolution similar to that reported with a commercial thermal modulator. Replacing the PDMS phase in the μTM with a trigonal-tricationic room temperature ionic liquid eliminated the bleed observed with the PDMS, but also reduced the capacity for several test compounds. Regardless, the demonstrated capability to independently temperature program this low resource μTM enhances its versatility and its promise for use in bench-scale GC×GC systems. PMID:27036209

  16. A Small-Scale Low-Cost Gas Chromatograph

    ERIC Educational Resources Information Center

    Gros, Natasa; Vrtacnik, Margareta

    2005-01-01

    The design and application of a small-scale portable gas chromatograph for learning of the basic concepts of chromatography is described. The apparatus consists of two basic separable units, which includes a chromatographic unit and an electronic unit.

  17. A low-power pressure-and temperature-programmed separation system for a micro gas chromatograph.

    SciTech Connect

    Sacks, Richard D. (University of Michigan, Ann Arbor, MI); Robinson, Alex Lockwood (Advanced Sensor Technologies, Albuquerque, NM); Lambertus, Gordon R. (University of Michigan, Ann Arbor, MI); Potkay, Joseph A. (University of Michigan, Ann Arbor, MI); Wise, Kensall D. (University of Michigan, Ann Arbor, MI)

    2006-10-01

    This thesis presents the theory, design, fabrication and testing of the microvalves and columns necessary in a pressure- and temperature-programmed micro gas chromatograph ({micro}GC). Two microcolumn designs are investigated: a bonded Si-glass column having a rectangular cross section and a vapor-deposited silicon oxynitride (Sion) column having a roughly circular cross section. Both microcolumns contain integrated heaters and sensors for rapid, controlled heating. The 3.2 cm x 3.2 cm, 3 m-long silicon-glass column, coated with a non-polar polydimethylsiloxane (PDMS) stationary phase, separates 30 volatile organic compounds (VOCs) in less than 6 min. This is the most efficient micromachined column reported to date, producing greater than 4000 plates/m. The 2.7 mm x 1.4 mm Sion column eliminates the glass sealing plate and silicon substrate using deposited dielectrics and is the lowest power and fastest GC column reported to date; it requires only 11 mW to raise the column temperature by 100 C and has a response time of 11s and natural temperature ramp rate of 580 C/min. A 1 m-long PDMS-coated Sion microcolumn separates 10 VOCs in 52s. A system-based design approach was used for both columns.

  18. Microfabricated packed gas chromatographic column

    DOEpatents

    Kottenstette, Richard; Matzke, Carolyn M.; Frye-Mason, Gregory C.

    2003-12-16

    A new class of miniaturized gas chromatographic columns has been invented. These chromatographic columns are formed using conventional micromachining techniques, and allow packed columns having lengths on the order of a meter to be fabricated with a footprint on the order of a square centimeter.

  19. Microminiature gas chromatographic column

    NASA Technical Reports Server (NTRS)

    Donaldson, R. W., Jr.

    1972-01-01

    Techniques commonly used for fabrication of integrated circuits are utilized to produce long capillary tubes for microminiature chromatographs. Method involves bonding of flat silicon plate to top of spirally grooved silicon chip to close groove and form capillary column.

  20. EVALUATION OF PORTABLE GAS CHROMATOGRAPHS

    EPA Science Inventory

    Limits of detection, linearity of responses, and stability of response factors and retention times for five commercially-available portable gas chromatographs (PGC) were determined during laboratory evaluation. he PGCs were also operated at the French Limited Superfund site near ...

  1. Chromatographic separation of cholesterol in foods.

    PubMed

    Fenton, M

    1992-10-30

    Based on the current literature and on experience gained in the laboratory, a simplified procedure using direct saponification (0.4 M potassium hydroxide in ethanol and heating at 60 degrees C for 1 h) is the most appropriate method for the determination of total cholesterol in foods. Extraction of the unsaponifiable matter with hexane is efficient and no extra clean-up is required before quantification. An internal standard, 5 alpha-cholestane or epicoprostanol, should be added to the sample prior to saponification and, together with reference standards, carried through the entire procedure to ensure accurate results. A significant improvement in cholesterol methodology has been achieved by decreasing the sample size and performing all the sample preparation steps in a single tube. The method has the advantages of elimination of an initial solvent extraction for total lipids and errors resulting from multiple extractions, transfers, filtration and wash steps after saponification. The resulting hexane extract, which contains a variety of sterols and fat soluble vitamins, requires an efficient capillary column for complete resolution of cholesterol from the other compounds present. The development of fused-silica capillary columns using cross-linked and bonded liquid phases has provided high thermal stability, inertness and separation efficiency and, together with automated cold on-column gas chromatographic injection systems, has resulted in reproducible cholesterol determinations in either underivatized or derivatized form. If free cholesterol and its esters need to be determined separately, they are initially extracted with other lipids with chloroform-methanol followed by their separation by column or thin-layer chromatography and subsequently analysed by gas or liquid chromatography. Although capillary gas chromatography offers superior efficiency in separation, the inherent benefits of liquid chromatography makes it a potential alternative. Isotope dilution

  2. Hand-held multiple system gas chromatograph

    DOEpatents

    Yu, Conrad M.

    2001-01-01

    A multiple parallel hand-held gas chromatograph (GC) system which includes several independent GCs. Each independent GC has its own injector, separation column, detector and oven and the GCs are mounted in a light weight hand-held assembly. Each GC operates independently and simultaneously. Because of different coatings in different separation columns, different retention times for the same gas will be measured. Thus, for a GC system with multiple parallel GCs, the system can measure, in a short period, different retention times and provide a cross-reference in the determination of the measured gas and to become a two-dimensional system for direct field use.

  3. Dual liquid and gas chromatograph system

    DOEpatents

    Gay, Don D.

    1985-01-01

    A chromatographic system that utilizes one detection system for gas chromatographic and micro-liquid chromatographic determinations. The detection system is a direct-current, atmospheric-pressure, helium plasma emission spectrometer. The detector utilizes a non-transparent plasma source unit which contains the plasma region and two side-arms which receive effluents from the micro-liquid chromatograph and the gas chromatograph. The dual nature of this chromatographic system offers: (1) extreme flexibility in the samples to be examined; (2) extremely low sensitivity; (3) element selectivity; (4) long-term stability; (5) direct correlation of data from the liquid and gas samples; (6) simpler operation than with individual liquid and gas chromatographs, each with different detection systems; and (7) cheaper than a commercial liquid chromatograph and a gas chromatograph.

  4. Dual liquid and gas chromatograph system

    DOEpatents

    Gay, D.D.

    A chromatographic system is described that utilizes one detection system for gas chromatographic and micro-liquid chromatographic determinations. The detection system is a direct-current, atmospheric-pressure, helium plasma emission spectrometer. The detector utilizes a nontransparent plasma source unit which contains the plasma region and two side-arms which receive effluents from the micro-liquid chromatograph and the gas chromatograph. The dual nature of this chromatographic system offers: (1) extreme flexibility in the samples to be examined; (2) extreme low sensitivity; (3) element selectivity; (4) long-term stability; (5) direct correlation of data from the liquid and gas samples; (6) simpler operation than with individual liquid and gas chromatographs, each with different detection systems; and (7) cheaper than a commercial liquid chromatograph and a gas chromatograph.

  5. A gas chromatograph/mass spectrometry method for determining isotopic distributions in organic compounds used in the chemical approach to stable isotope separation

    SciTech Connect

    Martinez, A.M.; Spall, W.D.; Smith, B.F.

    1990-01-01

    A variety of gas chromatograph/mass spectrometry (GC/MS) methods have been developed to resolve benzene, benzophenone, anthracene, fluorenone, and their respective stable isotope analogs from other components by gas chromatography. The ratio of stable isotope-labeled material to natural isotopic abundance compounds is determined from the mass spectra averaged across the chromatographic peak. Both total ion and selective ion chromatographic approaches were used for relative data and comparison. 9 refs., 11 tabs.

  6. Gas chromatographic separation of nitrogen, oxygen, argon, and carbon monoxide using custom-made porous polymers from high purity divinylbenzene

    NASA Technical Reports Server (NTRS)

    Pollock, G. E.; Ohara, D.; Hollis, O. L.

    1984-01-01

    Existing porous polymers were surveyed for their ability to separate the subject gases. Certain products that showed more promise than others were synthesized and the existing synthetic procedures studied and modified to produce new polymers with enhanced ability to separate the subject gases. Evaluation of the porous polymers was carried out practically by gas chromatography at ambient temperature. The modified synthetic procedures were somewhat simpler than the originals. The new porous polymers made with high purity divinylbenzene enabled use of shorter columns to obtain the separations desired.

  7. Fabrication of zeolitic imidazolate framework-8-methacrylate monolith composite capillary columns for fast gas chromatographic separation of small molecules.

    PubMed

    Yusuf, Kareem; Badjah-Hadj-Ahmed, Ahmed Yacine; Aqel, Ahmad; ALOthman, Zeid Abdullah

    2015-08-01

    A composite zeolitic imidazolate framework-8 (ZIF-8) with a butyl methacrylate-co-ethylene dimethacrylate (BuMA-co-EDMA) monolithic capillary column (33.5cm long×250μm i.d.) was fabricated to enhance the separation efficiency of methacrylate monoliths toward small molecules using conventional low-pressure gas chromatography in comparison with a neat butyl methacrylate-co-ethylene dimethacrylate (BuMA-co-EDMA) monolithic capillary column (33.5cm long×250μm i.d.). The addition of 10mgmL(-1) ZIF-8 micro-particles increased the BET surface area of BuMA-co-EDMA by 3.4-fold. A fast separation of five linear alkanes in 36s with high resolution (Rs≥1.3) was performed using temperature program. Isothermal separation of the same sample also showed a high efficiency (3315platesm(-1) for octane) at 0.89min. Moreover, the column was able to separate skeletal isomers, such as iso-octane/octane and 2-methyl octane/nonane. In addition, an iso-butane/iso-butylene gas mixture was separated at ambient temperature. Comparison with an open tubular TR-5MS column (30m long×250μm i.d.) revealed the superiority of the composite column in separating the five-membered linear alkane mixture with 4-5 times increase in efficiency and a total separation time of 0.89min instead of 4.67min. A paint thinner sample was fully separated using the composite column in 2.43min with a good resolution (Rs≥0.89). The perfect combination between the polymeric monolith, with its high permeability, and ZIF-8, with its high surface area and flexible 0.34nm pore openings, led to the fast separation of small molecules with high efficiency and opened a new horizon in GC applications. PMID:26141277

  8. Gas chromatographic separation of stereoisomers of non-protein amino acids on modified γ-cyclodextrin stationary phase.

    PubMed

    Fox, Stefan; Strasdeit, Henry; Haasmann, Stephan; Brückner, Hans

    2015-09-11

    Stereoisomers (enantiomers and diastereoisomers) of synthetic, non-protein amino acids comprising α-, β-, and γ-amino acids, including α,α-dialkyl amino acids, were converted into the respective N-trifluoroacetyl-O-methyl esters and analyzed and resolved by gas chromatography (GC) on a commercial fused silica capillary column coated with the chiral stationary phase octakis(3-O-butyryl-2,6-di-O-pentyl)-γ-cyclodextrin. This column is marketed under the trade name Lipodex(®) E. Chromatograms, retention times, and a chart displaying the retention times of approximately 40 stereoisomers of amino acids are presented. With few exceptions, baseline or almost baseline resolution was achieved for enantiomers and diastereoisomers. The chromatographic method presented is considered to be highly suitable for the elucidation of the stereochemistry of non-protein amino acids, for example in natural products, and for evaluating the enantiopurity of genetically non-coded amino acids used for the synthesis and design of conformationally tailored peptides. The method is applicable to extraterrestrial materials or can be used in experimental work related to abiotic syntheses or enantioselective destruction and amplification of amino acids. PMID:26278360

  9. GAS CHROMATOGRAPHIC TECHNIQUES FOR THE MEASUREMENT OF ISOPRENE IN AIR

    EPA Science Inventory

    The chapter discusses gas chromatographic techniques for measuring isoprene in air. Such measurement basically consists of three parts: (1) collection of sufficient sample volume for representative and accurate quantitation, (2) separation (if necessary) of isoprene from interfer...

  10. Relationship between chromatographic resolution and amide structure of chiral 2-hydroxy acids as O-(-)-menthoxycarbonylated diastereomeric derivatives for enantiomeric separation on achiral gas chromatography.

    PubMed

    Cha, Eunju; Kim, Sohee; Lee, Kang Mi; Kim, Ho Jun; Kim, Ki Hun; Kwon, Oh-Seung; Park, Ki Duk; Lee, Jaeick

    2016-02-15

    The relationship between chromatographic resolution and amide structure of chiral 2-hydroxy acids as O-(-)-menthoxycarbonylated diastereomeric derivatives on achiral gas chromatography was investigated to elucidate the best diastereomeric conformation for enantiomeric separation of chiral 2-hydroxy acids. Thirteen chiral 2-hydroxy acids were converted into nine different diastereomeric O-(-)-menthoxycarbonylated amide derivatives using the primary, secondary and cyclic amines to achieve complete enantiomeric separation through an achiral column. Each enantiomeric pair of 2-hydroxy acids as O-(-)-menthoxycarbonylated tert-butylamide derivatives was resolved on both the DB-5 and DB-17 columns with resolution factors ranging from 1.7 to 4.8 and 1.7 to 3.4, respectively. The results revealed that the structure of the amide moiety is shown to significantly affect chromatographic resolution. In addition, O-(-)-menthoxycarbonylated tert-butylamide derivatives were shown to be the best diastereomeric conformations for enantiomeric separation of 2-hydroxy acids. When comparing with our previous O-trifluoroacetylated(-)-menthyl ester derivatization method, the present results suggested that size differences between groups attached to the chiral center and conformational rigidity can have stronger effects on resolution than the distance between chiral centers. The elution of R- and S-stereoisomers was affected by the class of amine; i.e., primary, secondary, or cyclic, regardless of the substituents on the amine group, the structure of the 2-hydroxy acid, and the polarity of the column. PMID:26800225

  11. Gas chromatographic separation of bile acid 3-glucosides and 3-glucuronides without prior deconjugation on a stainless-steel capillary column.

    PubMed

    Iida, T; Tazawa, S; Tamaru, T; Goto, J; Nambara, T

    1995-01-01

    A method for the gas chromatographic (GC) separation of the 3-glucoside and 3-glucuronide conjugates of bile acids without the necessity for a hydrolytic step is described. The bile acid glycosides were derivatized to their complete methyl ester trimethylsilyl (Me-TMS) or methyl ester dimethylethylsilyl (Me-DMES) ether derivatives, which in turn were chromatographed on an inert and thermostable stainless-steel capillary column, Ultra ALLOY-1 (HT), coated with a thin film (0.15 micron) of chemically bonded and cross-linked dimethylsiloxane. They exhibited a single peak of the theoretical shape without any accompanying peaks due to thermal decomposition, even at oven temperatures of 320-330 degrees C. Excellent GC separation of isomeric bile acid glycosides was achieved by the combined use of suitable derivatives and column. This method, which does not need the prior deconjugation of the glycosidic moiety, could be usefully applied to biosynthetic and metabolic studies of bile acids in biological materials. PMID:7881536

  12. Estimating optimal time for fast chromatographic separations.

    PubMed

    Welch, Christopher J; Regalado, Erik L

    2014-09-01

    The term t(min cc) provides a ready estimate of the shortest time that can be obtained by "column cutting" for baseline resolution of two components showing excess chromatographic resolution. While actual column cutting is impractical, the t(min cc) value is shown to be closely related to the minimum separation time obtainable by adjusting other parameters such as flow rate, mobile phase composition, and temperature, affording scientists interested in the development of fast chromatographic separations a convenient tool for estimating the minimum separation time that can be obtained by modifying a given method development screening result. Furthermore, the relationship between t(min cc) and the minimum separation time obtainable by adjusting other parameters is shown to be dependent on the speed of the screening method, with aggressive screening gradients affording t(min cc) estimates that match the actual minimum separation time, and "lazy" screening gradients affording t(min cc) values that overestimate minimum separation time. Consequently, the analysis of the relationship between t(min cc) and actual minimum separation time may be a useful tool for determining the "fitness" of method development screening methods. PMID:24995384

  13. Evaluation of portable gas chromatographs

    SciTech Connect

    Berkley, R.E.; Miller, M.; Chang, J.C.; Oliver, K.; Fortune, C.

    1993-01-01

    Limits of detection, linearity of responses, and stability of response factors and retention times for five commercially-available portable gas chromatographs (PGC) were determined during laboratory evaluation. The PGCs were also operated at the French Limited Superfund site near Houston, TX during startup of bioremediation. Concentrations of volatile organic compounds (VOC) at the site were slightly above ambient background levels. Concurrent collocated grab samples were collected periodically in canisters and analyzed by Method TO-14 using a mass-selective detector. Canister data were taken to indicate correct concentrations and were used to assess the accuracy of PGC data. Durability, reliability, and complexity of operation of PGCs were also evaluated. The principal goal of the study was to determine the best way to use each instrument as a monitor for airborne VOCs.

  14. High performance hand-held gas chromatograph

    SciTech Connect

    Yu, C.M.

    1998-04-28

    The Microtechnology Center of Lawrence Livermore National Laboratory has developed a high performance hand-held, real time detection gas chromatograph (HHGC) by Micro-Electro-Mechanical-System (MEMS) technology. The total weight of this hand-held gas chromatograph is about five lbs., with a physical size of 8{close_quotes} x 5{close_quotes} x 3{close_quotes} including carrier gas and battery. It consumes about 12 watts of electrical power with a response time on the order of one to two minutes. This HHGC has an average effective theoretical plate of about 40k. Presently, its sensitivity is limited by its thermal sensitive detector at PPM. Like a conventional G.C., this HHGC consists mainly of three major components: (1) the sample injector, (2) the column, and (3) the detector with related electronics. The present HHGC injector is a modified version of the conventional injector. Its separation column is fabricated completely on silicon wafers by means of MEMS technology. This separation column has a circular cross section with a diameter of 100 pm. The detector developed for this hand-held GC is a thermal conductivity detector fabricated on a silicon nitride window by MEMS technology. A normal Wheatstone bridge is used. The signal is fed into a PC and displayed through LabView software.

  15. Versatile gas/particle ion chromatograph.

    PubMed

    Ullah, S M Rahmat; Takeuchi, Masaki; Dasgupta, Purnendu K

    2006-02-01

    A new, compact gas/particle ion chromatograph has been developed for measuring ionic constituents in PM2.5 (particulate matter of aerodynamic diameter < or = 2.5 microm) and water-soluble ionogenic gases. The instrument has separate sampling channels for gases and particles. In one, a membrane denuder collects soluble gases for preconcentration and analysis. In the other, a cyclone removes larger particles, a membrane denuder removes soluble gases, and a continuously wetted hydrophilic filter collects particles. A single, multiport, syringe pump handles liquid transport, and one conductivity detector measures anions and ammonium for both channels. Electrodialytically generated gradient hydroxide eluent permits 20 min chromatographic runs. Gas/particle samples are each collected for 40 min, butthe sampling intervals are staggered by 20 min. Liquid samples from the gas denuder and particle collector are aspirated and preconcentrated on sequential cation and anion concentrators and transferred respectively to an ammonia transfer device and an anion separation column. The flow configuration results in an ammonium peak before anion peaks in the chromatogram. The system measures ammonia, organic acids (such as acetic, formic, and oxalic acids), HCl, HONO, SO2, HNO3, and the corresponding ions in the aerosol phase. Low ng/m3 to sub-ng/m3 limits of detection (LODs) are attained for most common gases and particulate constituents, the LODs for gaseous SO2 to NH3 range, for example, from sub parts per trillion by volume (sub-pptv) to approximately 5 pptv. PMID:16509343

  16. Determination of methyl mercury by aqueous phase Eehylation, followed by gas chromatographic separation with cold vapor atomic fluorescence detection

    USGS Publications Warehouse

    De Wild, John F.; Olsen, Mark L.; Olund, Shane D.

    2002-01-01

    A recent national sampling of streams in the United States revealed low methyl mercury concentrations in surface waters. The resulting median and mean concentrations, calculated from 104 samples, were 0.06 nanograms per liter (ng/L) and 0.15 ng/L, respectively. This level of methyl mercury in surface water in the United States has created a need for analytical techniques capable of detecting sub-nanogram per liter concentrations. In an attempt to create a U.S. Geological Survey approved method, the Wisconsin District Mercury Laboratory has adapted a distillation/ethylation/ gas-phase separation method with cold vapor atomic fluorescence spectroscopy detection for the determination of methyl mercury in filtered and unfiltered waters. This method is described in this report. Based on multiple analyses of surface water and ground-water samples, a method detection limit of 0.04 ng/L was established. Precision and accuracy were evaluated for the method using both spiked and unspiked ground-water and surface-water samples. The percent relative standard deviations ranged from 10.2 to 15.6 for all analyses at all concentrations. Average recoveries obtained for the spiked matrices ranged from 88.8 to 117 percent. The precision and accuracy ranges are within the acceptable method-performance limits. Considering the demonstrated detection limit, precision, and accuracy, the method is an effective means to quantify methyl mercury in waters at or below environmentally relevant concentrations

  17. Gas separating

    DOEpatents

    Gollan, Arye

    1988-01-01

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing.

  18. Gas separating

    DOEpatents

    Gollan, Arye Z.

    1990-12-25

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing.

  19. Chromatographic Separations of Enantiomers and Underivatized Oligosaccharides

    SciTech Connect

    Ying Liu

    2004-12-19

    My graduate research has focused on separation science and bioanalytical analysis, which emphasized in method development. It includes three major areas: enantiomeric separations using high performance liquid chromatography (HPLC), Super/subcritical fluid chromatography (SFC), and capillary electrophoresis (CE); drug-protein binding behavior studies using CE; and carbohydrate analysis using liquid chromatograph-electrospray ionization mass spectrometry (LC-ESI-MS). Enantiomeric separations continue to be extremely important in the pharmaceutical industry. An in-depth evaluation of the enantiomeric separation capabilities of macrocyclic glycopeptides CSPs with SFC mobile phases was investigated using a set of over 100 chiral compounds. It was found that the macrocyclic based CSPs were able to separate enantiomers of various compounds with different polarities and functionalities. Seventy percent of all separations were achieved in less than 4 min due to the high flow rate (4.0 ml/min) that can be used in SFC. Drug-protein binding is an important process in determining the activity and fate of a drug once it enters the body. Two drug/protein systems have been studied using frontal analysis CE method. More sensitive fluorescence detection was introduced in this assay, which overcame the problem of low sensitivity that is common when using UV detection for drug-protein studies. In addition, the first usage of an argon ion laser with 257 nm beam coupled with CCD camera as a frontal analysis detection method enabled the simultaneous observation of drug fluorescence as well as the protein fluorescence. LC-ESI-MS was used for the separation and characterization of underivatized oligosaccharide mixtures. With the limits of detection as low as 50 picograms, all individual components of oligosaccharide mixtures (up to 11 glucose-units long) were baseline resolved on a Cyclobond I 2000 column and detected using ESI-MS. This system is characterized by high chromatographic

  20. Gas chromatograph injection port protective device

    NASA Technical Reports Server (NTRS)

    Robertson, M. D.; Welz, E. A.

    1969-01-01

    To prevent samples containing foreign matter from poisoning the gas chromatographic columns, a pre-filter insertion is placed in the injection port. The packing becomes a variable reactant, for example, acids are removed by using an alkaline liquid.

  1. A Quantitative Gas Chromatographic Ethanol Determination.

    ERIC Educational Resources Information Center

    Leary, James J.

    1983-01-01

    Describes a gas chromatographic experiment for the quantitative determination of volume percent ethanol in water ethanol solutions. Background information, procedures, and typical results are included. Accuracy and precision of results are both on the order of two percent. (JN)

  2. Gas separating

    DOEpatents

    Gollan, A.Z.

    1990-12-25

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing. 3 figs.

  3. Gas separating

    DOEpatents

    Gollan, A.

    1988-03-29

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing. 3 figs.

  4. Gas chromatographic analysis of trace gas impurities in tungsten hexafluoride.

    PubMed

    Laurens, J B; de Coning, J P; Swinley, J M

    2001-03-01

    Highly reactive fluorinated gaseous matrices require special equipment and techniques for the gas chromatographic analysis of trace impurities in these gases. The impurities that were analysed at the low-microg/l levels included oxygen, nitrogen, carbon dioxide, carbon monoxide, sulfur hexafluoride and hydrogen. This paper describes the use of a system utilising backflush column switching to protect the columns and detectors in the analysis of trace gas impurities in tungsten hexafluoride. Two separate channels were used for the analysis of H2, O2, N2, CO, CO2 and SF6 impurities with pulsed discharge helium ionisation detection. PMID:11269587

  5. 40 CFR 1065.267 - Gas chromatograph.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 33 2011-07-01 2011-07-01 false Gas chromatograph. 1065.267 Section 1065.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon Measurements § 1065.267 Gas...

  6. 40 CFR 1065.267 - Gas chromatograph.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Gas chromatograph. 1065.267 Section 1065.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon Measurements § 1065.267 Gas...

  7. Portable gas chromatograph-mass spectrometer

    SciTech Connect

    Andresen, B.D.; Eckels, J.D.; Kimmins, J.F.; Myers, D.W.

    1994-12-31

    A gas chromatograph-mass spectrometer (GC-MS) for use as a field portable organic chemical analysis instrument. The GC-MS is designed to be contained in a standard size suitcase, weighs less than 70 pounds, and requires less than 600 watts of electrical power at peak power (all systems on). The GC-MS includes: a conduction heated, forced air cooled small bore capillary gas chromatograph, a small injector assembly, a self-contained ion/sorption pump vacuum system, a hydrogen supply, a dual computer system used to control the hardware and acquire spectrum data, and operational software used to control the pumping system and the gas chromatograph. This instrument incorporates a modified commercial quadrupole mass spectrometer to achieve the instrument sensitivity and mass resolution characteristic of laboratory bench top units.

  8. Portable gas chromatograph-mass spectrometer

    DOEpatents

    Andresen, Brian D.; Eckels, Joel D.; Kimmons, James F.; Myers, David W.

    1996-01-01

    A gas chromatograph-mass spectrometer (GC-MS) for use as a field portable organic chemical analysis instrument. The GC-MS is designed to be contained in a standard size suitcase, weighs less than 70 pounds, and requires less than 600 watts of electrical power at peak power (all systems on). The GC-MS includes: a conduction heated, forced air cooled small bore capillary gas chromatograph, a small injector assembly, a self-contained ion/sorption pump vacuum system, a hydrogen supply, a dual computer system used to control the hardware and acquire spectrum data, and operational software used to control the pumping system and the gas chromatograph. This instrument incorporates a modified commercial quadrupole mass spectrometer to achieve the instrument sensitivity and mass resolution characteristic of laboratory bench top units.

  9. Portable gas chromatograph-mass spectrometer

    DOEpatents

    Andresen, B.D.; Eckels, J.D.; Kimmons, J.F.; Myers, D.W.

    1996-06-11

    A gas chromatograph-mass spectrometer (GC-MS) is described for use as a field portable organic chemical analysis instrument. The GC-MS is designed to be contained in a standard size suitcase, weighs less than 70 pounds, and requires less than 600 watts of electrical power at peak power (all systems on). The GC-MS includes: a conduction heated, forced air cooled small bore capillary gas chromatograph, a small injector assembly, a self-contained ion/sorption pump vacuum system, a hydrogen supply, a dual computer system used to control the hardware and acquire spectrum data, and operational software used to control the pumping system and the gas chromatograph. This instrument incorporates a modified commercial quadrupole mass spectrometer to achieve the instrument sensitivity and mass resolution characteristic of laboratory bench top units. 4 figs.

  10. Gas-liquid chromatographic determination of morphine, heroin, and cocaine.

    PubMed

    Prager, M J; Harrington, S M; Governo, T F

    1979-03-01

    Morphine, heroin, and cocaine are quantitatively determined with the same gas-liquid chromatographic system. The compounds are separated on a 6 ft X 2 mm id glass column packed with a 1:1 mixture of 5% SE-30 on 80--100 mesh Chromosorb W and 3% OV-17 on 80--100 mesh Varaport 30. The column is temperature-programmed. Flame ionization detector responses are measured with a computer-based data system. Heroin and cocaine are chromatographed directly; morphine is derivatized first. The procedure was evaluated with previously analyzed commercial and forensic samples. Accuracy and precision were 5 and 3%, respectively. PMID:447602

  11. AUTOMATED MEASUREMENTS OF INFRARED SPECTRA OF CHROMATOGRAPHICALLY SEPARATED FRACTIONS

    EPA Science Inventory

    The rapid identification of trace organic pollutants in water presents one of the more severe problems for environmental analytical chemists today. Spectroscopic identifications of chromatographically separated fractions, preferably without trapping each sample, yields more certa...

  12. Gas chromatograph-mass spectrometer (GC/MS) system for quantitative analysis of reactive chemical compounds

    DOEpatents

    Grindstaff, Quirinus G.

    1992-01-01

    Described is a new gas chromatograph-mass spectrometer (GC/MS) system and method for quantitative analysis of reactive chemical compounds. All components of such a GC/MS system external to the oven of the gas chromatograph are programmably temperature controlled to operate at a volatilization temperature specific to the compound(s) sought to be separated and measured.

  13. A nonlinear model for gas chromatograph systems

    NASA Technical Reports Server (NTRS)

    Feinberg, M. P.

    1975-01-01

    Fundamental engineering design techniques and concepts were studied for the optimization of a gas chromatograph-mass spectrometer chemical analysis system suitable for use on an unmanned, Martian roving vehicle. Previously developed mathematical models of the gas chromatograph are found to be inadequate for predicting peak heights and spreading for some experimental conditions and chemical systems. A modification to the existing equilibrium adsorption model is required; the Langmuir isotherm replaces the linear isotherm. The numerical technique of Crank-Nicolson was studied for use with the linear isotherm to determine the utility of the method. Modifications are made to the method eliminate unnecessary calculations which result in an overall reduction of the computation time of about 42 percent. The Langmuir isotherm is considered which takes into account the composition-dependent effects on the thermodynamic parameter, mRo.

  14. Development of Gas Chromatographic Mass Spectrometry.

    PubMed

    Hites, Ronald A

    2016-07-19

    Gas chromatographic mass spectrometry is now widely used for the quantitation and identification of organic compounds in almost any imaginable sample. These applications include the measurement of chlorinated dioxins in soil samples, the identification of illicit drugs in human blood, and the quantitation of accelerants in arson investigations, to name just a few. How did GC/MS get so popular? It turns out that it required parallel developments in mass spectrometry, gas chromatography, and computing and that no one person "invented" the technique. This Perspective traces this history from the 1950s until today. PMID:27384908

  15. GAS CHROMATOGRAPH-BASED SYSTEM FOR MEASURING THE METHANE FRACTION OF DIESEL ENGINE HYDROCARBON EMISSIONS

    EPA Science Inventory

    An instrument has been developed (termed the 'methane analytical system') enabling diesel methane emissions to be quatified separately from total unburned hydrocarbon emissions. The instrument employed gas chromatographic principles whereby a molecular sieve column operating isot...

  16. Economic gas chromatograph system for subambient pressure gas sampling

    NASA Technical Reports Server (NTRS)

    Mitchell, S. M.

    1970-01-01

    Gas chromatograph sampling system consists of a manifold with a gas-sample valve, a minimum-volume pressure transducer with a portable monitor, a vacuum-source valve, and a sample inlet valve. Increased accuracy of analysis is obtained by better control of sample size.

  17. Chromatographic methods for the isolation, separation and characterisation of dissolved organic matter.

    PubMed

    Sandron, Sara; Rojas, Alfonso; Wilson, Richard; Davies, Noel W; Haddad, Paul R; Shellie, Robert A; Nesterenko, Pavel N; Kelleher, Brian P; Paull, Brett

    2015-09-01

    This review presents an overview of the separation techniques applied to the complex challenge of dissolved organic matter characterisation. The review discusses methods for isolation of dissolved organic matter from natural waters, and the range of separation techniques used to further fractionate this complex material. The review covers both liquid and gas chromatographic techniques, in their various modes, and electrophoretic based approaches. For each, the challenges that the separation and fractionation of such an immensely complex sample poses is critically reviewed. PMID:26290053

  18. Chromatographically separable rotamers of an unhindered amide

    PubMed Central

    Geffe, Mario; Andernach, Lars; Trapp, Oliver

    2014-01-01

    Summary Surprisingly stable formamide rotamers were encountered in the tetrahydroisoquinoline and morphinan series of alkaloids. We investigated the hindered rotation around the amide bond by dynamic high-performance liquid chromatography (DHPLC) and kinetic measurements of the interconversion of the rotamers which can readily be separated by HPLC as well as TLC. The experimental results of the different methods were compared to each other as well as to results obtained by DFT calculations. PMID:24778722

  19. Optimizing Chromatographic Separation: An Experiment Using an HPLC Simulator

    ERIC Educational Resources Information Center

    Shalliker, R. A.; Kayillo, S.; Dennis, G. R.

    2008-01-01

    Optimization of a chromatographic separation within the time constraints of a laboratory session is practically impossible. However, by employing a HPLC simulator, experiments can be designed that allow students to develop an appreciation of the complexities involved in optimization procedures. In the present exercise, a HPLC simulator from "JCE…

  20. Detection system for a gas chromatograph

    DOEpatents

    Hayes, John M.; Small, Gerald J.

    1984-01-01

    A method and apparatus are described for the quantitative analysis of vaporizable compounds, and in particular of polycyclic aromatic hydrocarbons which may be induced to fluoresce. The sample to be analyzed is injected into a gas chromatography column and is eluted through a narrow orifice into a vacuum chamber. The free expansion of the eluted sample into the vacuum chamber creates a supersonic molecular beam in which the sample molecules are cooled to the extent that the excited vibrational and rotational levels are substantially depopulated. The cooled molecules, when induced to fluoresce by laser excitation, give greatly simplified spectra suitable for analytical purposes. The laser induced fluorimetry provides great selectivity, and the gas chromatograph provides quantitative transfer of the sample to the molecular beam.

  1. High-separation efficiency micro-fabricated multi-capillary gas chromatographic columns for simulants of the nerve agents and blister agents

    PubMed Central

    2014-01-01

    To achieve both high speed and separation efficiency in the separation of a mixture of nerve and blister agent simulants, a high-aspect-ratio micro-fabricated multi-capillary column (MCC, a 50-cm-long, 450-μm-deep, and 60-μm-wide four-capillary column) was fabricated by the application of the microelectromechanical system (MEMS) techniques. Mixtures of chemical warfare agent (CWA) simulants - dimethyl methylphosphonate (DMMP), triethyl phosphate (TEP), and methyl salicylate - were used as samples. The fabricated MCC allowed for the separation of all the components of the gaseous mixture within 24 s, even when the difference in boiling point was 4°C, as in the case of TEP and methyl salicylate. Furthermore, interfering agents - dichloromethane, ethanol, and toluene - were also included in the subsequent gaseous mixture samples. The boiling point of these six components ranged from 78°C to 219°C. All six components were clearly separated within 70 s. This study is the first to report the clear separation of gas mixtures of components with close boiling points. The column efficiency was experimentally determined to be 12,810 plates/m. PMID:24899869

  2. High-separation efficiency micro-fabricated multi-capillary gas chromatographic columns for simulants of the nerve agents and blister agents

    NASA Astrophysics Data System (ADS)

    Li, Yi; Du, Xiaosong; Wang, Yang; Tai, Huiling; Qiu, Dong; Lin, Qinghao; Jiang, Yadong

    2014-05-01

    To achieve both high speed and separation efficiency in the separation of a mixture of nerve and blister agent simulants, a high-aspect-ratio micro-fabricated multi-capillary column (MCC, a 50-cm-long, 450-μm-deep, and 60-μm-wide four-capillary column) was fabricated by the application of the microelectromechanical system (MEMS) techniques. Mixtures of chemical warfare agent (CWA) simulants - dimethyl methylphosphonate (DMMP), triethyl phosphate (TEP), and methyl salicylate - were used as samples. The fabricated MCC allowed for the separation of all the components of the gaseous mixture within 24 s, even when the difference in boiling point was 4°C, as in the case of TEP and methyl salicylate. Furthermore, interfering agents - dichloromethane, ethanol, and toluene - were also included in the subsequent gaseous mixture samples. The boiling point of these six components ranged from 78°C to 219°C. All six components were clearly separated within 70 s. This study is the first to report the clear separation of gas mixtures of components with close boiling points. The column efficiency was experimentally determined to be 12,810 plates/m.

  3. FTIR gas chromatographic analysis of perfumes

    NASA Astrophysics Data System (ADS)

    Diederich, H.; Stout, Phillip J.; Hill, Stephen L.; Krishnan, K.

    1992-03-01

    Perfumes, natural or synthetic, are complex mixtures consisting of numerous components. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) techniques have been extensively utilized for the analysis of perfumes and essential oils. A limited number of perfume samples have also been analyzed by FT-IR gas chromatographic (GC-FTIR) techniques. Most of the latter studies have been performed using the conventional light pipe (LP) based GC-FTIR systems. In recent years, cold-trapping (in a matrix or neat) GC-FTIR systems have become available. The cold-trapping systems are capable of sub-nanogram sensitivities. In this paper, comparison data between the LP and the neat cold-trapping GC- FTIR systems is presented. The neat cold-trapping interface is known as Tracer. The results of GC-FTIR analysis of some commercial perfumes is also presented. For comparison of LP and Tracer GC-FTIR systems, a reference (synthetic) mixture containing 16 major and numerous minor constituents was used. The components of the mixture are the compounds commonly encountered in commercial perfumes. The GC-FTIR spectra of the reference mixture was obtained under identical chromatographic conditions from an LP and a Tracer system. A comparison of the two sets of data thus generated do indeed show the enhanced sensitivity level of the Tracer system. The comparison also shows that some of the major components detected by the Tracer system were absent from the LP data. Closer examination reveals that these compounds undergo thermal decomposition on contact with the hot gold surface that is part of the LP system. GC-FTIR data were obtained for three commercial perfume samples. The major components of these samples could easily be identified by spectra search against a digitized spectral library created using the Tracer data from the reference mixture.

  4. Gas Chromatographic Detectors for Exobiology Flight Experiments

    NASA Technical Reports Server (NTRS)

    Kojiro, Daniel R.; Humphry, Donald E.; Takeuchi, Nori; Chang, Sherwood (Technical Monitor)

    1997-01-01

    Exobiology flight experiments require highly sensitive instrumentation for in situ chemical analysis of the volatile chemical species that occur in the atmospheres and surfaces of various bodies within the solar system. The complex mixtures encountered place a heavy burden on the analytical instrumentation to detect and identify all species present. Future missions to Mars', comets, or planetary moons such as Europa, will perform experiments with complex analyses. In addition, instrumentation for such missions must perform under severely restricted conditions with limited resources. To meet these analytical requirements, improved methods and highly sensitive yet smaller instruments must continually be developed with increasingly greater capabilities. We describe here efforts to achieve this objective, for past and future missions, through the development of new or the improvement of existing sensitive, miniaturized gas chromatographic detectors.

  5. FIELD COMPARISON OF PORTABLE GAS CHROMATOGRAPHS WITH METHOD TO-14

    EPA Science Inventory

    A field-deployable prototype fast gas chromatograph (FGC) and two commercially-available portable gas chromatographs (PGC) were evaluated by measuring organic vapors in ambient air at a field monitoring site in metropolitan San Juan, Puerto Rico. he data were compared with simult...

  6. Gas-Chromatographic Determination Of Water In Freon PCA

    NASA Technical Reports Server (NTRS)

    Melton, Donald M.

    1994-01-01

    Gas-chromatographic apparatus measures small concentrations of water in specimens of Freon PCA. Testing by use of apparatus faster and provides greater protection against accidental contamination of specimens by water in testing environment. Automated for unattended operation. Also used to measure water contents of materials, other than Freon PCA. Innovation extended to development of purgeable sampling accessory for gas chromatographs.

  7. Rotating annular chromatograph for continuous metal separations and recovery

    SciTech Connect

    Begovich, J.M.; Sisson, W.G.

    1981-01-01

    Multicomponent liquid chromatographic separations have been achieved by using a slowly rotating annular bed of sorbent material. By continuously introducing the feed material to be separated at a stationary point at the top of the bed and eluent everywhere else around the annulus, elution chromatography occurs. The rotation of the sorbent bed causes the separated components to appear as helical bands, each of which has a characteristic, stationary exit point; hence, the separation process is truly continuous. The concept has been developed primarily on a 279-mm-diam by 0.6-m-long device with a 12.7-mm-wide annulus. The effect of annulus width and diameter has recently been studied using the same device with a 50.8-mm-wide annulus and another 0.6-m-long chromatograph with an 89-mm diameter and annulus widths of 6.4, 12.7, and 22.2 mm. These columns have been constructed of Plexiglas and typically operate at a gauge pressure of 175 kPa. To further study the effect of size and pressure, a new 445-mm-diam by 1-m-long column with a 31.8-mm-wide annulus has been fabricated. Its metal construction allows preparative-scale operation with a wide variety of liquids at pressures to 1.3 MPa. Three metal recovery systems have been explored: (1) separation of iron and aluminum in ammonium sulfate-sulfuric acid solutions; (2) separation of hafnium from zirconium in sulfuric acid solutions; and (3) the separation of copper, nickel, and cobalt in ammonium carbonate solutions. This last system simulates the leach liquor of the Caron process for recovering nickel and cobalt from laterite ores. It has been studied, using similar conditions, on each of the chromatographs, and the results demonstrate the effect of column dimensions on the quality and quantity of the separation. 8 figures, 1 table.

  8. Characterization of Gas Chromatographic Liquid Phases Using McReynolds Constants. An Experiment for Instrumental Analysis Laboratory.

    ERIC Educational Resources Information Center

    Erskine, Steven R.; And Others

    1986-01-01

    Describes a laboratory experiment that is designed to aid in the understanding of the fundamental process involved in gas chromatographic separations. Introduces the Kovats retention index system for use by chemistry students to establish criteria for the optimal selection of gas chromatographic stationary phases. (TW)

  9. Graphene-ZIF8 composite material as stationary phase for high-resolution gas chromatographic separations of aliphatic and aromatic isomers.

    PubMed

    Yang, Xiaohong; Li, Changxia; Qi, Meiling; Qu, Liangti

    2016-08-19

    This work presents the separation performance of graphene-ZIF8 (G-Z) composite material as stationary phase for capillary gas chromatography (GC). The G-Z stationary phase achieved high column efficiency of 5000 plates/m determined by n-dodecane (k=1.22) at 120°C and showed weakly polar nature. Importantly, it exhibited high selectivity and resolving capability for branched alkane isomers and aromatic positional isomers, showing clear advantages over the reported neat graphene and ZIF8. In addition, it attained high resolution for geometric cis-/trans-isomers. The G-Z column exhibited good column thermal stability up to 300°C and column repeatability with RSD values of retention times in the range of 0.01-0.19% for intra-day, 0.05-0.88% for inter-day and 0.66-5.6% for between-column, respectively, Moreover, the G-Z column was employed for the determination of minor impurity isomers in real reagent samples, which demonstrates its promising potential in GC applications. PMID:27423773

  10. On-line gas chromatographic analysis of airborne particles

    DOEpatents

    Hering, Susanne V.; Goldstein, Allen H.

    2012-01-03

    A method and apparatus for the in-situ, chemical analysis of an aerosol. The method may include the steps of: collecting an aerosol; thermally desorbing the aerosol into a carrier gas to provide desorbed aerosol material; transporting the desorbed aerosol material onto the head of a gas chromatography column; analyzing the aerosol material using a gas chromatograph, and quantizing the aerosol material as it evolves from the gas chromatography column. The apparatus includes a collection and thermal desorption cell, a gas chromatograph including a gas chromatography column, heated transport lines coupling the cell and the column; and a quantization detector for aerosol material evolving from the gas chromatography column.

  11. Simple gas chromatographic method for furfural analysis.

    PubMed

    Gaspar, Elvira M S M; Lopes, João F

    2009-04-01

    A new, simple, gas chromatographic method was developed for the direct analysis of 5-hydroxymethylfurfural (5-HMF), 2-furfural (2-F) and 5-methylfurfural (5-MF) in liquid and water soluble foods, using direct immersion SPME coupled to GC-FID and/or GC-TOF-MS. The fiber (DVB/CAR/PDMS) conditions were optimized: pH effect, temperature, adsorption and desorption times. The method is simple and accurate (RSD<8%), showed good recoveries (77-107%) and good limits of detection (GC-FID: 1.37 microgL(-1) for 2-F, 8.96 microgL(-1) for 5-MF, 6.52 microgL(-1) for 5-HMF; GC-TOF-MS: 0.3, 1.2 and 0.9 ngmL(-1) for 2-F, 5-MF and 5-HMF, respectively). It was applied to different commercial food matrices: honey, white, demerara, brown and yellow table sugars, and white and red balsamic vinegars. This one-step, sensitive and direct method for the analysis of furfurals will contribute to characterise and quantify their presence in the human diet. PMID:18976770

  12. Multi-objective optimization of chromatographic rare earth element separation.

    PubMed

    Knutson, Hans-Kristian; Holmqvist, Anders; Nilsson, Bernt

    2015-10-16

    The importance of rare earth elements in modern technological industry grows, and as a result the interest for developing separation processes increases. This work is a part of developing chromatography as a rare earth element processing method. Process optimization is an important step in process development, and there are several competing objectives that need to be considered in a chromatographic separation process. Most studies are limited to evaluating the two competing objectives productivity and yield, and studies of scenarios with tri-objective optimizations are scarce. Tri-objective optimizations are much needed when evaluating the chromatographic separation of rare earth elements due to the importance of product pool concentration along with productivity and yield as process objectives. In this work, a multi-objective optimization strategy considering productivity, yield and pool concentration is proposed. This was carried out in the frame of a model based optimization study on a batch chromatography separation of the rare earth elements samarium, europium and gadolinium. The findings from the multi-objective optimization were used to provide with a general strategy for achieving desirable operation points, resulting in a productivity ranging between 0.61 and 0.75 kgEu/mcolumn(3), h(-1) and a pool concentration between 0.52 and 0.79 kgEu/m(3), while maintaining a purity above 99% and never falling below an 80% yield for the main target component europium. PMID:26375205

  13. Ion chromatographic separation and quantitation of alkyl methylamines and ethylamines in atmospheric gas and particulate matter using preconcentration and suppressed conductivity detection.

    PubMed

    VandenBoer, T C; Markovic, M Z; Petroff, A; Czar, M F; Borduas, N; Murphy, J G

    2012-08-24

    Two methods based on ion chromatography (IC) were developed for the detection of methyl and ethyl alkyl amines (methylamine (MA), ethylamine (EA), dimethylamine (DMA), diethylamine (DEA), trimethylamine (TMA) and triethylamine (TEA)) and NH(3)/NH(4)(+) in online atmospheric gas-particle and size-resolved particulate samples. The two IC methods were developed to analyze samples collected with an ambient ion monitor (AIM), an online gas-particle collection system, or with a Micro Orifice Uniform Deposit Impactor (MOUDI) for size-resolved particle samples. These methods enable selective and (semi-) quantitative detection of alkyl amines at ambient atmospheric concentrations (pptv and pgm(-3)) in samples where significant interferences can be expected from Na(+) and NH(4)(+), for example marine and rural air masses. Sample pre-concentration using a trace cation column enabled instrumental detection limits on the order of pmol (sub-ng) levels per sample, an improvement of up to 10(2) over current IC methods. Separation was achieved using a methanesulfonic acid gradient elution on Dionex CS12A and CS17 columns. The relative standard deviations in retention times during 3 weeks continuous (hourly) sampling campaigns ranged from 0.1 to 0.5% and 0.2 to 5% for the CS12A and CS17 across a wide dynamic range of atmospheric concentrations. Resolution of inorganic and organic cations is limited to 25min for online samples. Mass-dependent coelution of NH(4)(+)/MA/EA occurred on the CS12A column and DEA/TMA coeluted on both columns. Calibrations of ammonium show a non-linear response across the entire calibration range while all other analytes exhibit high linearity (R(2)=0.984-0.999), except for EA and TEA on the CS12A (R(2)=0.960 and 0.941, respectively). Both methods have high analytical accuracy for the nitrogenous bases ranging from 9.5 to 20% for NH(3) and <5-15% for the amines. Hourly observations of amines at Egbert, ON in October 2010 showed gaseous DMA and TMA+DEA at 1

  14. Gas chromatographic characterization of vegetable oil deodorization distillate.

    PubMed

    Verleyen, T; Verhe, R; Garcia, L; Dewettinck, K; Huyghebaert, A; De Greyt, W

    2001-07-01

    Because of its complex nature, the analysis of deodorizer distillate is a challenging problem. Deodorizer distillate obtained from the deodorization process of vegetable oils consists of many components including free fatty acids, tocopherols, sterols, squalene and neutral oil. A gas chromatographic method for the analysis of deodorizer distillate without saponification of the sample is described. After a concise sample preparation including derivatization and silylation, distillate samples were injected on column at 60 degrees C followed by a gradual increase of the oven temperature towards 340 degrees C. The temperature profile of the oven was optimized in order to obtain a baseline separation of the different distillate components including free fatty acids, tocopherols, sterols, squalene and neutral oil. Good recoveries for delta-tocopherol, alpha-tocopherol, stigmasterol and cholesteryl palmitate of 97, 94.4, 95.6 and 92%, respectively were obtained. Repeatability of the described gas chromatographic method was evaluated by analyzing five replicates of a soybean distillate. Tocopherols and sterols had low relative standard deviations ranging between 1.67 and 2.25%. Squalene, mono- and diacylglycerides had higher relative standard deviations ranging between 3.33 and 4.12%. Several industrial deodorizer distillates obtained from chemical and physical refining of corn, canola, sunflower and soybean have been analyzed for their composition. PMID:11471811

  15. Gas Chromatographic Determination of Enrivonmentally Significant Pesticides.

    ERIC Educational Resources Information Center

    Rudzinski, Walter E.; Beu, Steve

    1982-01-01

    A chromatographic procedure for analyzing organophosphorus pesticides (such as PCB's, nitrosamines, and phthalate esters) in orange juice is described, including a summary of the method, instrumentation, methodology, results/discussion, and calculations. (JN)

  16. [Chromatographic separation of plasmid DNA by anion-exchange cryogel].

    PubMed

    Guo, Yantao; Shen, Shaochuan; Yun, Junxian; Yao, Kejian

    2012-08-01

    Plasmid DNA (pDNA) is used as an important vector for gene therapy, and its wide application is restricted by the purity and yield. To obtain high-purity pDNA, a chromatographic method based on anion-exchange supermacroporous cryogel was explored. The anion-exchange cryogel was prepared by grafting diethylaminoethyl-dextran to the epoxide groups of polyacrylamide-based matrix and pUC19 plasmid was used as a target to test the method. The plasmid was transferred into Escherichia coli DH5alpha, cultivated, harvested and lysed. The obtained culture was centrifuged and the supernatant was used as the plasmid feedstock, which was loaded into the anion-exchange cryogel bed for chromatographic separation. By optimizing the pH of running buffer and the elution conditions, high-purity pDNA was obtained by elution with 0.5 mol/L sodium chloride solution at pH 6.6. Compared to the traditional methods for purification of pDNA, animal source enzymes and toxic reagents were not involved in the present separation process, ensuring the safety of both the purification operations and the obtained pDNA. PMID:23185899

  17. Mathematical model for multicomponent separations on the continuous annular chromatograph

    SciTech Connect

    Bratzler, R.L.; Begovich, J.M.

    1980-12-01

    A model for multicomponent separations on ion exchange columns has been adapted for use in studying the performance of the continuous annular chromatograph. The model accurately predicts solute peak positions in the column effluent and qualitatively predicts trends in solute effluent resolution as a function of increasing bandwidth of the solute feed pulse. The major virtues of the model are its simplicity in terms of the calculations involved and the fact that it incorporates the nonlinear solute-resin binding isotherms common in many ion exchange separations. Because dispersion effects are not accounted for in the model, discrepancies exist between the shapes of the effluent peaks predicted by the model and those determined experimentally.

  18. Role of substituents in cyclodextrin derivatives for enantioselective gas chromatographic separation of chiral terpenoids in the essential oils of Mentha spicata.

    PubMed

    Pragadheesh, V S; Yadav, Anju; Chanotiya, Chandan Singh

    2015-10-01

    Enantioselective GC-FID and enantioselective GC-MS have been utilized under temperature gradient mode with differently substituted heptakis- and octakis-cyclodextrins to achieve the resolution of chiral terpenoids in the essential oil of indigenously grown cultivars of Mentha spicata. Modified cyclodextrins were derivatized in GC column for the separation of chiral terpenoids. A 2,3-diethyl-6-tert-butyldimethylsilyl-β-cyclodextrin doped into 14% cyanopropylphenyl/86%dimethylpolysiloxane (TBDE-β-CD) showed good enantioselectivity for all the studied chiral compounds excluding carvone. Carvone enantiomers were well resolved in 2,3-diacetoxy-6-tert-butyldimethylsilyl-β-cyclodextrin column (TBDA-β-CD) with enantioseparation (Es) of 1.006. A TBDE-β-CD provides maximum enantiomeric separation for β-pinene (Es 1.038), sabinene (Es 1.051), limonene (Es 1.045), isomenthone (Es 1.029) and α-terpineol (Es 1.014). Furthermore, enantiomer elution order reversal was observed for sabinene, menthone, terpinen-4-ol and menthol while changing from β- to γ-cyclodextrin phase. Carvone exhibits enantiomer elution order reversal by changing substituents i.e., methyl to acetyl at 2- & 3- position of the cyclodextrin derivative. Chiral constituents such as (+)-isomenthone, (-)-menthone, (1R,2S,5R)-(-)-menthol and (4S)-(+)-piperitone exist as a single enantiomer with >99% excess. Existence of (R)-(+)-limonene and (S)-(+)-carvone enantiomers has been proven first time in M. spicata essential oils and can be used as the marker for Indian origin. PMID:26310896

  19. Optimization of preparative chromatographic separation of multiple rare earth elements.

    PubMed

    Max-Hansen, Mark; Ojala, Frida; Kifle, Dejene; Borg, Niklas; Nilsson, Bernt

    2011-12-23

    This work presents a method to optimize multi-product chromatographic systems with multiple objective functions. The system studied is a neodymium, samarium, europium, gadolinium mixture separated in an ion exchange chromatography step. A homogeneous Langmuir Mobile Phase Modified model is calibrated to fit the experiments, and then used to perform the optimization task. For the optimization a multi-objective Differential Evolution algorithm was used, with weighting based on relative value of the components to find optimal operation points along the Pareto front. The objectives of the Pareto front are weighted productivity and weighted yield with purity as an equality constraint. A prioritizing scheme based on relative values is applied for determining the pooling order. A simple rule of thumb for pooling strategy selection is presented. The multi-objective optimization gives a Pareto front which shows the rule of thumb, as a gap in one of the objective functions. PMID:22079482

  20. Gas chromatograph-combustion system for 14C-accelerator mass spectrometry.

    PubMed

    McIntyre, Cameron P; Sylva, Sean P; Roberts, Mark L

    2009-08-01

    A gas chromatograph-combustion (GC-C) system is described for the introduction of samples as CO(2) gas into a (14)C accelerator mass spectrometry (AMS) system with a microwave-plasma gas ion source. Samples are injected into a gas chromatograph fitted with a megabore capillary column that uses H(2) as the carrier gas. The gas stream from the outlet of the column is mixed with O(2) and Ar gas and passed through a combustion furnace where the H(2) carrier gas and separated components are quantitatively oxidized to CO(2) and H(2)O. Water vapor is removed using a heated nafion dryer. The Ar carries the CO(2) to the ion source. The system is able to separate and oxidize up to 10 microg of compound and transfer the products from 7.6 mL/min of H(2) carrier gas into 0.2-1.0 mL/min of Ar carrier gas. Chromatographic performance and isotopic fidelity satisfy the requirements of the (14)C-AMS system for natural abundance measurements. The system is a significant technical advance for GC-AMS and may be capable of providing an increase in sensitivity for other analytical systems such as an isotope-ratio-monitoring GC/MS. PMID:19572555

  1. Gas chromatographic analysis of volatiles in fluid and gas inclusions.

    PubMed

    Andrawes, F; Holzer, G; Roedder, E; Gibson, E K; Oro, J

    1984-01-01

    Most geological samples and some synthetic materials contain fluid inclusions. These inclusions preserve for us tiny samples of the liquid and/or the gas phase that was present during formation, although in some cases they may have undergone significant changes from the original material. Studies of the current composition of the inclusions provide data on both the original composition and the change since trapping. These conclusions are seldom larger than 1 millimeter in diameter. The composition varies from a single major compound (e.g., water) in a single phase to a very complex mixture in one or more phases. The concentration of some of the compounds present may be at trace levels. We present here some analyses of inclusion on a variety of geological samples, including diamonds. We used a sample crusher and a gas chromatography-mass spectrometry (GC-MS) system to analyze for organic and inorganic volatiles present as major to trace constituents in inclusions. The crusher is a hardened stainless-steel piston cylinder apparatus with tungsten carbide crushing surfaces, and is operated in a pure helium atmosphere at a controlled temperature. Samples ranging from 1 mg to 1 g were crushed and the released volatiles were analyzed using multi-chromatographic columns and detectors, including the sensitive helium ionization detector. Identification of the GC peaks was carried out by GC-MS. This combination of procedures has been shown to provide geochemically useful information on the processes involved in the history of the samples analyzed. PMID:11541990

  2. Gas chromatographic analysis of volatiles in fluid and gas inclusions

    USGS Publications Warehouse

    Andrawes, F.; Holzer, G.; Roedder, E.; Gibson, E.K., Jr.; Oro, J.

    1984-01-01

    Most geological samples and some synthetic materials contain fluid inclusions. These inclusions preserve for us tiny samples of the liquid and/or the gas phase that was present during formation, although in some cases they may have undergone significant changes from the original material. Studies of the current composition of the inclusions provide data on both the original composition and the change since trapping. These inclusions are seldom larger than 1 millimeter in diameter. The composition varies from a single major compound (e.g., water) in a single phase to a very complex mixture in one or more phases. The concentration of some of the compounds present may be at trace levels. We present here some analyses of inclusions in a variety of geological samples, including diamonds. We used a sample crusher and a gas chromatography-mass spectrometry (GC-MS) system to analyze for organic and inorganic volatiles present as major to trace constituents in inclusions. The crusher is a hardened stainless-steel piston cylinder apparatus with tungsten carbide crusing surfaces, and is operated in a pure helium atmosphere at a controlled temperature. Samples ranging from 1 mg to 1 g were crushed and the released volatiles were analyzed using multi-chromatographic columns and detectors, including the sensitive helium ionization detector. Identification of the GC peaks was carried out by GC-MS. This combination of procedures has been shown to provide geochemically useful information on the process involved in the history of the samples analyzed. ?? 1984.

  3. Gas-separation process

    DOEpatents

    Toy, Lora G.; Pinnau, Ingo; Baker, Richard W.

    1994-01-01

    A process for separating condensable organic components from gas streams. The process makes use of a membrane made from a polymer material that is glassy and that has an unusually high free volume within the polymer material.

  4. GAS CHROMATOGRAPHIC MICROMETHOD FOR TRACE DETERMINATIONS OF PHENOLS

    EPA Science Inventory

    A gas chromatographic procedure is described for the analysis of a variety of substituted phenols from water samples. The method was designed for situations when the sample size is very limited (0.5 to 1.0 ml), such as in laboratory microcosm experiments on transport and fate of ...

  5. [A gas chromatographic method for determining acetaldehyde in cadaver blood].

    PubMed

    Savich, V I; Valladares, Kh A; Gusakov, Iu A; Skachko, Z M

    1990-01-01

    Gas-chromatographic method of acetaldehyde detection in blood of subjects who died of alcoholic intoxication is suggested. Method is simple, does not require additional expenses, can be readily used in medicolegal practice and in difficult cases it may help the expert to make an objective conclusion on the cause of death. PMID:2087747

  6. Gas chromatographic column for the Viking 1975 molecular analysis experiment

    NASA Technical Reports Server (NTRS)

    Novotny, M.; Hayes, J. M.; Bruner, F.; Simmonds, P. G.

    1975-01-01

    A gas chromatographic column has been developed for use in the remote analysis of the Martian surface. The column, which utilizes a liquid-modified organic adsorbent (Tenax) as the stationary phase, provides efficient transmission and resolution of nanogram quantities of organic materials in the presence of millionfold excesses of water and carbon dioxide.

  7. Hydrodynamic gas mixture separation

    SciTech Connect

    Stolyarov, A.A.

    1982-02-10

    The separation of gas mixtures is the basis of many chemical, petrochemical, and gas processes. Classical separation methods (absorption, adsorption, condensation, and freezing) require cumbersome and complex equipment. No adequate solution is provided by the cheapening and simplification of gas-processing apparatus and separation methods by hydration and diffusion. For example, an apparatus for extracting helium from natural gas by diffusion has a throughput of gas containing 0.45% helium of 117,000 m/sup 3//h and in the first stage has teflon membranes working at a pressure difference of 63.3x10/sup 5/ Pa of area 79,000 m/sup 2/, and the specific cost of the apparatus was 8500 dollars per m/sup 3//h of helium. Therefore, vigorous studies are being conducted on new ways of efficient separation of gas mixtures that are cheaper and simpler. Here we consider a novel method of physically essentially reversible separation of gas mixtures, which involves some features of single-phase supersonic flows.

  8. Gas separation membranes

    DOEpatents

    Schell, William J.

    1979-01-01

    A dry, fabric supported, polymeric gas separation membrane, such as cellulose acetate, is prepared by casting a solution of the polymer onto a shrinkable fabric preferably formed of synthetic polymers such as polyester or polyamide filaments before washing, stretching or calendering (so called griege goods). The supported membrane is then subjected to gelling, annealing, and drying by solvent exchange. During the processing steps, both the fabric support and the membrane shrink a preselected, controlled amount which prevents curling, wrinkling or cracking of the membrane in flat form or when spirally wound into a gas separation element.

  9. Mars Solar Balloon Landed Gas Chromatograph Mass Spectrometer

    NASA Technical Reports Server (NTRS)

    Mahaffy, P.; Harpold, D.; Niemann, H.; Atreya, S.; Gorevan, S.; Israel, G.; Bertaux, J. L.; Jones, J.; Owen, T.; Raulin, F.

    1999-01-01

    payload based Micromissions, it is essential to implement an even broader chemical analysis and to enable a significant extension of previous isotope measurements. Such a development would enhance the presently very active study of questions of atmospheric evolution and loss and past climatic conditions. The method selected to implement this program can be based on well-established mass spectrometry techniques. Sampled gas is chemically and physically processed to separate the gas mixture into components using gas chromatograph and related enrichment techniques. This allows trace species to be identified and reveals isotopic distributions in many cases with improved precision. Samples of interest, such as organic molecules, may lie deep below the highly oxidized surface layer and the suggested program includes enhanced sampling techniques to measure volatiles preserved in solid phase material deep below the surface as well as gas from the well mixed atmosphere.

  10. Gas-separation process

    DOEpatents

    Toy, L.G.; Pinnau, I.; Baker, R.W.

    1994-01-25

    A process is described for separating condensable organic components from gas streams. The process makes use of a membrane made from a polymer material that is glassy and that has an unusually high free volume within the polymer material. 6 figures.

  11. Polymide gas separation membranes

    DOEpatents

    Ding, Yong; Bikson, Benjamin; Nelson, Joyce Katz

    2004-09-14

    Soluble polyamic acid salt (PAAS) precursors comprised of tertiary and quaternary amines, ammonium cations, sulfonium cations, or phosphonium cations, are prepared and fabricated into membranes that are subsequently imidized and converted into rigid-rod polyimide articles, such as membranes with desirable gas separation properties. A method of enhancing solubility of PAAS polymers in alcohols is also disclosed.

  12. 21 CFR 862.2230 - Chromatographic separation material for clinical use.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... chromatographic separation material for clinical use is a device accessory (e.g., ion exchange absorbents, ion exchagne resins, and ion papers) intended for use in ion exchange chromatography, a procedure in which...

  13. 21 CFR 862.2230 - Chromatographic separation material for clinical use.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... chromatographic separation material for clinical use is a device accessory (e.g., ion exchange absorbents, ion exchagne resins, and ion papers) intended for use in ion exchange chromatography, a procedure in which...

  14. 21 CFR 862.2230 - Chromatographic separation material for clinical use.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... chromatographic separation material for clinical use is a device accessory (e.g., ion exchange absorbents, ion exchagne resins, and ion papers) intended for use in ion exchange chromatography, a procedure in which...

  15. 21 CFR 862.2230 - Chromatographic separation material for clinical use.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... chromatographic separation material for clinical use is a device accessory (e.g., ion exchange absorbents, ion exchagne resins, and ion papers) intended for use in ion exchange chromatography, a procedure in which...

  16. 21 CFR 862.2230 - Chromatographic separation material for clinical use.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... chromatographic separation material for clinical use is a device accessory (e.g., ion exchange absorbents, ion exchagne resins, and ion papers) intended for use in ion exchange chromatography, a procedure in which...

  17. Computerized gas chromatographic-mass spectrometric analysis of polycyclic aromatic hydrocarbons in environmental samples.

    PubMed

    Lao, R C; Thomas, R S; Monkman, J L

    1975-10-29

    Substantial progress has been made in the last few years in the development of a rapid method for determining polycyclic aromatic hydrocarbons (PAH) in environmental samples. The three-step method consists of (i) a preliminary separation of PAH by solvent and/or column chromatography, (ii) identification by a combination of gas chromatography with quadrupole mass spectrometry and computer, and (iii) measurement by computerized gas chromatography using internal standards. Samples of industrial effluents, coke oven emissions, coal tar and airborne particulates have been investigated. The efficiencies of different gas chromatographic columns were evaluated during these investigations. PMID:1184696

  18. The Gas Chromatograph Mass Spectrometer for the Huygens Probe

    NASA Astrophysics Data System (ADS)

    Niemann, H. B.; Atreya, S. K.; Bauer, S. J.; Biemann, K.; Block, B.; Carignan, G. R.; Donahue, T. M.; Frost, R. L.; Gautier, D.; Haberman, J. A.; Harpold, D.; Hunten, D. M.; Israel, G.; Lunine, J. I.; Mauersberger, K.; Owen, T. C.; Raulin, F.; Richards, J. E.; Way, S. H.

    2002-07-01

    The Gas Chromatograph Mass Spectrometer (GCMS) on the Huygens Probe will measure the chemical composition of Titan's atmosphere from 170 km altitude (˜1 hPa) to the surface (˜1500 hPa) and determine the isotope ratios of the major gaseous constituents. The GCMS will also analyze gas samples from the Aerosol Collector Pyrolyser (ACP) and may be able to investigate the composition (including isotope ratios) of several candidate surface materials. The GCMS is a quadrupole mass filter with a secondary electron multiplier detection system and a gas sampling system providing continuous direct atmospheric composition measurements and batch sampling through three gas chromatographic (GC) columns. The mass spectrometer employs five ion sources sequentially feeding the mass analyzer. Three ion sources serve as detectors for the GC columns and two are dedicated to direct atmosphere sampling and ACP gas sampling respectively. The instrument is also equipped with a chemical scrubber cell for noble gas analysis and a sample enrichment cell for selective measurement of high boiling point carbon containing constituents. The mass range is 2 to 141 Dalton and the nominal detection threshold is at a mixing ratio of 10- 8. The data rate available from the Probe system is 885 bit/s. The weight of the instrument is 17.3 kg and the energy required for warm up and 150 minutes of operation is 110 Watt-hours.

  19. The Gas Chromatograph Mass Spectrometer for the Huygens Probe

    NASA Astrophysics Data System (ADS)

    Niemann, H. B.; Atreya, S. K.; Bauer, S. J.; Biemann, K.; Block, B.; Carignan, G. R.; Donahue, T. M.; Frost, R. L.; Gautier, D.; Haberman, J. A.; Harpold, D.; Hunten, D. M.; Israel, G.; Lunine, J. I.; Mauersberger, K.; Owen, T. C.; Raulin, F.; Richards, J. E.; Way, S. H.

    2002-07-01

    The Gas Chromatograph Mass Spectrometer (GCMS) on the Huygens Probe will measure the chemical composition of Titan's atmosphere from 170 km altitude (~1 hPa) to the surface (~1500 hPa) and determine the isotope ratios of the major gaseous constituents. The GCMS will also analyze gas samples from the Aerosol Collector Pyrolyser (ACP) and may be able to investigate the composition (including isotope ratios) of several candidate surface materials. The GCMS is a quadrupole mass filter with a secondary electron multiplier detection system and a gas sampling system providing continuous direct atmospheric composition measurements and batch sampling through three gas chromatographic (GC) columns. The mass spectrometer employs five ion sources sequentially feeding the mass analyzer. Three ion sources serve as detectors for the GC columns and two are dedicated to direct atmosphere sampling and ACP gas sampling respectively. The instrument is also equipped with a chemical scrubber cell for noble gas analysis and a sample enrichment cell for selective measurement of high boiling point carbon containing constituents. The mass range is 2 to 141 Dalton and the nominal detection threshold is at a mixing ratio of 10- 8. The data rate available from the Probe system is 885 bit/s. The weight of the instrument is 17.3 kg and the energy required for warm up and 150 minutes of operation is 110 Watt-hours.

  20. Chromatographic separation and concentration of quercetin and (+)-catechin using mesoporous composites based on MCM-41

    NASA Astrophysics Data System (ADS)

    Karpov, S. I.; Belanova, N. A.; Korabel'nikova, E. O.; Nedosekina, I. V.; Roessner, F.; Selemenev, V. F.

    2015-05-01

    Data on chromatographic separation of quercetin and (+)-catechin-flavonoids with similar physicochemical (including sorption) properties—are presented. The highest efficiency of chromatographic process at high sorption capacity of the material with respect to quercetin and slightly lower capacity for (+)-catechin were observed when silylated composites of ordered MCM-41 type materials were used. The application of acetonitrile as a solvent increased the sorption capacity of the material and can be recommended for separation of related polyphenol substances and their determination using ordered MCM-41 modified with trimethylchlorosilane as a stationary phase in a chromatographic column.

  1. Liquid/Gas Vortex Separator

    NASA Technical Reports Server (NTRS)

    Morris, B. G.

    1986-01-01

    Liquid/gas separator vents gas from tank of liquid that contains gas randomly distributed in bubbles. Centrifugal force separates liquid and gas, forcing liquid out of vortex tube through venturi tube. Gas vented through exhaust port. When liquid detected in vent tube, exhaust port closed, and liquid/gas mixture in vent tube drawn back into tank through venturi.

  2. Gas chromatographic concepts for the analysis of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Valentin, J. R.; Cullers, D. K.; Hall, K. W.; Krekorian, R. L.; Phillips, J. B.

    1991-01-01

    Over the last few years, new gas chromatographic (GC) concepts were developed for use on board spacecraft or any other restricted environments for determining the chemical composition of the atmosphere and surface material of various planetary bodies. Future NASA Missions include an entry probe that will be sent to Titan and various spacecraft that will land on Mars. In order to be able to properly respond to the mission science requirements and physical restrictions imposed on the instruments by these missions, GC analytical techniques are being developed. Some of these techniques include hardware and mathematical techniques that will improve GC sensitivity and increase the sampling rate of a GC descending through a planetary atmosphere. The technique of Multiplex Gas Chromatography (MGC) is an example of a technique that was studied in a simulated Titan atmosphere. In such an environment, the atmospheric pressure at instrument deployment is estimated to be a few torr. Thus, at such pressures, the small amount of sample that is acquired might not be enough to satisfy the detection requirements of the gas chromatograph. In MGC, many samples are pseudo-randomly introduced to the chromatograph without regard to elution of preceding components. The resulting data is then reduced using mathematical techniques such as cross-correlation of Fourier Transforms. Advantages realized from this technique include: improvement in detection limits of several orders of magnitude and increase in the number of analyses that can be conducted in a given period of time. Results proving the application of MGC at very low pressures emulating the same atmospheric pressures that a Titan Probe will encounter when the instruments are deployed are presented. The sample used contained hydrocarbons that are expected to be found in Titan's atmosphere. In addition, a new selective modulator was developed to monitor water under Martian atmospheric conditions. Since this modulator is selective only

  3. Preliminary numerical analysis of improved gas chromatograph model

    NASA Technical Reports Server (NTRS)

    Woodrow, P. T.

    1973-01-01

    A mathematical model for the gas chromatograph was developed which incorporates the heretofore neglected transport mechanisms of intraparticle diffusion and rates of adsorption. Because a closed-form analytical solution to the model does not appear realizable, techniques for the numerical solution of the model equations are being investigated. Criteria were developed for using a finite terminal boundary condition in place of an infinite boundary condition used in analytical solution techniques. The class of weighted residual methods known as orthogonal collocation is presently being investigated and appears promising.

  4. Gas-chromatographic characterization of physicochemical properties of astatine compounds

    SciTech Connect

    Norseev, Yu.V.

    1995-07-01

    The organoastatine compounds obtained were identified by gas-liquid chromatography on a specially designed gas radiochromatograph with detection of eluted compounds both by their radioactivity and by thermal conductivity. Gas-liquid chromatography is the most efficient method for separation and identification of volatile organoastatine compounds.

  5. Gas separation membrane module assembly

    DOEpatents

    Wynn, Nicholas P; Fulton, Donald A.

    2009-03-31

    A gas-separation membrane module assembly and a gas-separation process using the assembly. The assembly includes a set of tubes, each containing gas-separation membranes, arranged within a housing. The housing contains a tube sheet that divides the space within the housing into two gas-tight spaces. A permeate collection system within the housing gathers permeate gas from the tubes for discharge from the housing.

  6. Improved Chromatographic Separation of Sitagliptin Phosphate and Metformin Hydrochloride.

    PubMed

    Hendy, Moataz S

    2015-12-01

    New UPLC method was developed for determination of sitagliptin and metformin using Symmetry C18 column (100 mm × 2.1 mm, 2.2 μm) and isocratic elution (methanol 20%), pH (3.5) as a mobile phase. The ultraviolet detector was operated at 220 nm and the column temperature was 50°C. Linearity parameters were acceptable over the concentration ranges of 2-12 μgml(-1) and 5-35 μgml(-1) for sitagliptin and metformin, respectively. The variables were premeditated to adjust the chromatographic conditions using design of experiment. The proposed method was proved to be accurate for the quality control of the mentioned drugs in their pharmaceutical dosage form. PMID:26759536

  7. Improved Chromatographic Separation of Sitagliptin Phosphate and Metformin Hydrochloride

    PubMed Central

    Hendy, Moataz S.

    2015-01-01

    New UPLC method was developed for determination of sitagliptin and metformin using Symmetry C18 column (100 mm × 2.1 mm, 2.2 μm) and isocratic elution (methanol 20%), pH (3.5) as a mobile phase. The ultraviolet detector was operated at 220 nm and the column temperature was 50°C. Linearity parameters were acceptable over the concentration ranges of 2-12 μgml-1 and 5-35 μgml-1 for sitagliptin and metformin, respectively. The variables were premeditated to adjust the chromatographic conditions using design of experiment. The proposed method was proved to be accurate for the quality control of the mentioned drugs in their pharmaceutical dosage form. PMID:26759536

  8. High-performance liquid-chromatographic separation of subcomponents of antimycin-A

    USGS Publications Warehouse

    Abidi, S.L.

    1988-01-01

    Using a reversed-phase high-performance liquid chromatographic (HPLC) technique, a mixture of antimycins A was separated into eight hitherto unreported subcomponents, Ala, Alb, A2a, A2b, A3a, A3b, A4a, and A4b. Although a base-line resolution of the known four major antimycins Al, A2, A3, and A4 was readily achieved with mobile phases containing acetate buffers, the separation of the new antibiotic subcomponents was highly sensitive to variation in mobile phase conditions. The type and composition of organic modifiers, the nature of buffer salts, and the concentration of added electrolytes had profound effects on capacity factors, separation factors, and peak resolution values. Of the numerous chromatographic systems examined, a mobile phase consisting of methanol-water (70:30) and 0.005 M tetrabutylammonium phosphate at pH 3.0 yielded the most satisfactory results for the separation of the subcomponents. Reversed-phase gradient HPLC separation of the dansylated or methylated antibiotic compounds produced superior chromatographic characteristics and the presence of added electrolytes was not a critical factor for achieving separation. Differences in the chromatographic outcome between homologous and structural isomers were interpretated based on a differential solvophobic interaction rationale. Preparative reversed-phase HPLC under optimal conditions enabled isolation of pure samples of the methylated antimycin subcomponents for use in structural studies.

  9. Optical chromatographic sample separation of hydrodynamically focused mixtures

    PubMed Central

    Terray, A.; Hebert, C. G.; Hart, S. J.

    2014-01-01

    Optical chromatography relies on the balance between the opposing optical and fluid drag forces acting on a particle. A typical configuration involves a loosely focused laser directly counter to the flow of particle-laden fluid passing through a microfluidic device. This equilibrium depends on the intrinsic properties of the particle, including size, shape, and refractive index. As such, uniquely fine separations are possible using this technique. Here, we demonstrate how matching the diameter of a microfluidic flow channel to that of the focusing laser in concert with a unique microfluidic platform can be used as a method to fractionate closely related particles in a mixed sample. This microfluidic network allows for a monodisperse sample of both polystyrene and poly(methyl methacrylate) spheres to be injected, hydrodynamically focused, and completely separated. To test the limit of separation, a mixed polystyrene sample containing two particles varying in diameter by less than 0.5 μm was run in the system. The analysis of the resulting separation sets the framework for continued work to perform ultra-fine separations. PMID:25553179

  10. A bubble-based microfluidic gas sensor for gas chromatographs.

    PubMed

    Bulbul, Ashrafuzzaman; Kim, Hanseup

    2015-01-01

    We report a new proof-of-concept bubble-based gas sensor for a gas chromatography system, which utilizes the unique relationship between the diameters of the produced bubbles with the gas types and mixture ratios as a sensing element. The bubble-based gas sensor consists of gas and liquid channels as well as a nozzle to produce gas bubbles through a micro-structure. It utilizes custom-developed software and an optical camera to statistically analyze the diameters of the produced bubbles in flow. The fabricated gas sensor showed that five types of gases (CO2, He, H2, N2, and CH4) produced (1) unique volumes of 0.44, 0.74, 1.03, 1.28, and 1.42 nL (0%, 68%, 134%, 191%, and 223% higher than that of CO2) and (2) characteristic linear expansion coefficients (slope) of 1.38, 2.93, 3.45, 5.06, and 5.44 nL/(kPa (μL s(-1))(-1)). The gas sensor also demonstrated that (3) different gas mixture ratios of CO2 : N2 (100 : 0, 80 : 20, 50 : 50, 20 : 80 and 0 : 100) generated characteristic bubble diameters of 48.95, 77.99, 71.00, 78.53 and 99.50 μm, resulting in a linear coefficient of 10.26 μm (μL s(-1))(-1). It (4) successfully identified an injection (0.01 μL) of pentane (C5) into a continuous carrier gas stream of helium (He) by monitoring bubble diameters and creating a chromatogram and demonstrated (5) the output stability within only 5.60% variation in 67 tests over a month. PMID:25350655

  11. Gas and liquid chromatographic analyses of nimodipine calcium antagonist in blood plasma and cerebrospinal fluid.

    PubMed

    Krol, G J; Noe, A J; Yeh, S C; Raemsch, K D

    1984-01-13

    Gas (GC) and liquid chromatographic (LC) assay procedures were developed for analysis of nimodipine (1,4-dihydropyridine calcium antagonist, BAY e 9736) in blood plasma at low nanogram concentration levels. To avoid decomposition during gas chromatography, nimodipine was oxidized to nimodipine pyridine (P) analogue before it was chromatographed on the OV-17 column and quantitated using an electron-capture detector. In contrast, the LC procedure involved chromatographic separation and quantitation of the underivatized nimodipine and of the endogenous P analogue using a 3-micron Spherisorb ODS column and UV detection. The same plasma extract and three alternative internal standards were used for both assays. Taking into consideration the fact that the GC assay result includes endogenous P analogue as well as nimodipine, good correlation between GC and LC assay data was obtained. Comparison of the results observed with the two procedures confirmed the accuracy of each procedure and provided an alternative when one of the assay results was subject to patient plasma constituent interference. The LC assay was also used for analysis of the demethylated metabolites of nimodipine. To detect sub-nanogram concentrations of nimodipine in cerebrospinal fluid a combined LC-GC procedure using an LC clean-up step and a GC quantitation step was also developed. The above GC and LC procedures were used to obtain preliminary pharmacokinetic data. PMID:6707134

  12. The gas chromatographic resolution of DL-isovaline

    NASA Technical Reports Server (NTRS)

    Flores, J. J.; Bonner, W. A.; Van Dort, M. A.

    1977-01-01

    Isovaline is of cosmological interest because it is one of the 12 non-protein amino acids which have been isolated from the Murchison meteorite, and unlike the other chiral amino acids in this meteorite, it has no alpha-hydrogen at its asymmetric center and hence cannot racemize by the customary alpha-hydrogen-dependent mechanisms which engender racemization in ordinary amino acids. Experiments were conducted in which a .01 M solution of N-TFA-DL-isovalyl-L-leucine isopropyl ester in nitromethane was injected into the capillary column of a gas chromatograph coupled to a digital electronic integrator-recorder. Efflux times and integrated peak area percents are shown next to each diastereometer peak.

  13. Prediction of gas chromatographic retention data for hydrocarbons from naphthas

    SciTech Connect

    Woloszyn, T.F.; Jurs, P.C. )

    1993-03-01

    Regression equations that model the gas chromatographic retention behavior of hydrocarbons found in complex petrochemical mixtures were developed for two different stationary phases, SE-30 and Carbowax 20M. The models had relative standard errors in the range 1--2%. This quantitative structure-retention relationship (QSRR) study focused on a relatively heterogeneous data set and resulted in the generation of several statistical models that related Kovats' retention index with descriptors that encode molecular structure. Also investigated was the addition of boiling point as a physicochemical descriptor. These models bore a significant improvement over the models containing only structural descriptors, with R values of 0.996. 27 refs., 4 figs., 8 tabs.

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

    NASA Technical Reports Server (NTRS)

    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

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

    PubMed

    Valentin, J R

    1989-03-01

    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

  16. Chromatographic purification and size separation of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Duesberg, G. S.; Muster, J.; Krstic, V.; Burghard, M.; Roth, S.

    1998-08-01

    The efficient purification of single-wall and multi-wall carbon nanotubes (NTs) by columnar size exclusion chromatography (SEC) is reported. In this process, carbon nanospheres (polyhedra), amorphous carbon and metal particles are removed from aqueous surfactant-stabilised dispersions of NT raw material. TEM and AFM investigations revealed that more than 40-50% of the purified material consists of individual tubes. In addition, length separation of the tubes is achieved.

  17. Chromatographic size separation of single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Duesberg, G. S.; Muster, J.; Krstic, V.; Burghard, M.; Roth, S.

    The efficient purification of single-wall carbon nanotubes (SWNTs) is reported. Carbon nanospheres, metal particles, and amorphous carbon could be successfully removed by size exclusion chromatography (SEC) applied to surfactant stabilised dispersions of SWNT raw material. In addition, length separation of the tubes was achieved. The SWNTs obtained can be adsorbed in high densities onto chemically modified substrates. As determined by AFM investigations, the purified material consists of about equal fractions of both individual SWNTS and ropes of SWNTs.

  18. Thin-Layer Chromatographic Separation of Phenols: An Undergraduate Laboratory Experiment.

    ERIC Educational Resources Information Center

    Kurth, Mark J.

    1986-01-01

    Background information, procedures used, and equipment needed are provided for an experiment in which a series of readily available, inexpensive, and relatively nontoxic phenols are separated using thin-layer chromatographic techniques. The experiment permits a discussion of how relative Rf values may be rationalized by considering a molecule's…

  19. A gas chromatographic air analyzer fabricated on a silicon wafer

    NASA Technical Reports Server (NTRS)

    Terry, S. C.; Jerman, J. H.; Angell, J. B.

    1979-01-01

    A miniature gas analysis system has been built based on the principles of gas chromatography (GC). The major components are fabricated in silicon using photolithography and chemical etching techniques, which allows size reductions of nearly three orders of magnitude compared to conventional laboratory instruments. The chromatography system consists of a sample injection valve and a 1.5-m-long separating capillary column, which are fabricated on a substrate silicon wafer. The output thermal conductivity detector is separately batch fabricated and integrably mounted on the substrate wafer. The theory of gas chromatography has been used to optimize the performance of the sensor so that separations of gaseous hydrocarbon mixtures are performed in less than 10 s. The system is expected to find application in the areas of portable ambient air quality monitors, implanted biological experiments, and planetary probes.

  20. Chemical characterization of Brickellia cavanillesii (Asteraceae) using gas chromatographic methods

    PubMed Central

    Eshiet, Etetor R; Zhu, Jinqiu; Anderson, Todd A; Smith, Ernest E

    2014-01-01

    A methanol extract of lyophilized Brickellia cavanillesii was quantitatively analyzed using gas chromatographic (GC) techniques. The chromatographic methods employed were (i) GC-flame ionization detector (GC-FID), (ii) GC-mass spectrometry (GC-MS), and (iii) purge and trap GC-MS (P&T GC-MS). Thirteen compounds were identified with a quality match of 90% and above using GC-MS. The compounds were (1) Cyclohexene, 6-ethenyl-6-methyl-1-(1-methylethyl)-3-(1-methylethylidene)-, (S)-; (2) Bicylo (2.2.1) heptan-2-one, 1, 7, 7-trimethyl-(1S, 4S)-; (3) Phenol, 2-methoxy-4-(1-propenyl)-; (4) Benzene, 1-(1, 5-dimethyl-4-hexenyl)-4-methyl-; (5) Naphthalene, 1, 2, 3, 5, 6, 8a-hexahydro4, 7-dimethyl-1-1-(1-methylethyl)-, (1S-cis)-; (6) Phenol, 2-methoxy-; (7) Benzaldehyde, 3-hydroxy-4-methoxy-; (8) 11, 13-Eicosadienoic acid, methyl ester; (9) 2-Furancarboxaldehyde, 5-methyl-; (10) Maltol; (11) Phenol; (12) Hydroquinone; (13) 1H-Indene, 1-ethylideneoctahydro-7a-methyl-, (1E, 3a.alpha, 7a.beta.). Other compounds (14) 3-methyl butanal; (15) (D)-Limonene; (16) 1-methyl-4-(1-methyl ethyl) benzene; (17) Butanoic acid methyl ester; (18) 2-methyl propanal; (19) 2-butanone; (20) 2-pentanone; and (21) 2-methyl butane were also identified when P&T GC-MS was performed. Of the 21 compounds identified, 12 were validated using chemical standards. The identified compounds were found to be terpenes, derivatives of terpenes, esters, ketones, aldehydes, and phenol-derived aromatic compounds; these are the primary constituents of the essential oils of many plants and flowers. PMID:24804069

  1. The Huygens Gas Chromatograph Mass Spectrometer Investigation Of Titan

    NASA Astrophysics Data System (ADS)

    Atreya, Sushil; Harpold, Dan; Owen, Tobias

    2015-04-01

    A decade ago, on 14 January 2005, the Huygens probe of the Cassini-Huygens mission descended through the smog filled atmosphere of Titan and landed on the surface, revealing for the first time the extraordinary nature of Saturn's largest moon. One of the six payload instruments, the gas chromatograph mass spectrometer (GCMS), was crucial for measuring the composition of the atmosphere and the surface of Titan [1,2]. Most of the GCMS findings were "firsts", including the first direct identification of molecular nitrogen as the bulk constituent of the atmosphere, first vertical profile of Titan's second most abundant volatile, methane, first determination of primordial and radiogenic argon, first quantification of a number of stable gas isotopes, and the first measurements of the make-up of Titan's surface. These data are key to understanding why Titan is so unique amongst planetary moons in possessing a massive atmosphere [3], how Titan maintains a cycle of methane complete with surface reservoirs, evaporation and condensation like the hydrological cycle on earth [3,4,5], and what is responsible for the photochemical smog on Titan that plays a central role in the very existence of an atmosphere on Titan [3]. This presentation will discuss the GCMS investigation and how it helped shape our current view of Titan. [website for downloading pdf's of relevant papers: www.umich.edu/~atreya] [1] Niemann, H. B. et al., The abundances of constituents of Titan's atmosphere from the GCMS instrument on the Huygens probe, Nature 438, 779-784, 2005. [2] Niemann, H. B. et al., The composition of Titan's lower atmosphere and simple surface volatiles as measured by the Cassini-Huygens probe gas chromatograph mass spectrometer experiment, J. Geophys. Res. (Planets) 115, 12006, 2010. [3] Atreya S. K., R. D. Lorenz and J. H. Waite, Volatile origin and cycles: Nitrogen and methane, in Titan from Cassini-Huygens, R. H. Brown, J. P. Lebreton and J. Waite, (eds.), Springer Dordrecht

  2. Ion chromatographic separation of inorganic ions using a combination of hydrophilic interaction chromatographic column and cation-exchange resin column.

    PubMed

    Arai, Kaori; Mori, Masanobu; Hironaga, Takahiro; Itabashi, Hideyuki; Tanaka, Kazuhiko

    2012-04-01

    A combination of hydrophilic interaction chromatographic (HILIC) column and a weakly acidic cation-exchange resin (WCX) column was used for simultaneous separation of inorganic anions and cations by ion chromatography (IC). Firstly, the capability of HILIC column for the separation of analyte ions was evaluated under acidic eluent conditions. The columns used were SeQuant ZIC-HILIC (ZIC-HILIC) with a sulfobetaine-zwitterion stationary phase (ZIC-HILIC) and Acclaim HILIC-10 with a diol stationary phase (HILIC-10). When using tartaric acid as the eluent, the HILIC columns indicated strong retentions for anions, based on ion-pair interaction. Especially, HILIC-10 could strongly retain anions compared with ZIC-HILIC. The selectivity for analyte anions of HILIC-10 with 5 mmol/L tartaric acid eluent was in the order of I(-) > NO3(-) > Br(-) > Cl(-) > H2PO4(-). However, since HILIC-10 could not separate analyte cations, a WCX column (TSKgel Super IC-A/C) was connected after the HILIC column in series. The combination column system of HILIC and WCX columns could successfully separate ten ions (Na+, NH4+, K+, Mg2+, Ca2+, H2PO4(-), Cl(-), Br(-), NO3(-) and I(-)) with elution of 4 mmol/L tartaric acid plus 8 mmol/L 18-crown-6. The relative standard deviations (RSDs) of analyte ions by the system were in the ranges of 0.02% - 0.05% in retention times and 0.18% - 5.3% in peak areas through three-time successive injections. The limits of detection at signal-to-noise ratio of 3 were 0.24 - 0.30 micromol/L for the cations and 0.31 - 1.2 micromol/L for the anions. This system was applied for the simultaneous determination of the cations and the anions in a vegetable juice sample with satisfactory results. PMID:22799200

  3. ToF-SIMS characterisation of diterpenoic acids after chromatographic separation

    NASA Astrophysics Data System (ADS)

    Oriňák, Andrej; Oriňáková, Renáta; Arlinghaus, Heinrich F.; Vering, Guido; Hellweg, Sebastian; Cechinel-Filho, Valdir

    2006-07-01

    Microcolumn liquid chromatography (μHPLC) coupled on-line with time of flight secondary ion mass spectrometry (ToF-SIMS) was applied for mixture of diterpenoic acids (abietic, gibberellic and kaurenoic) analysis. Chromatographic effluent, with analytes separated, was carried out directly onto different, ToF-SIMS compatible surface substrates, for further ToF-SIMS analysis. Silica gel Si 60, aluminium backplate modified Si 60, monolithic silica gel and Raman spectroscopy chromatographic thin layers were used as the deposition substrates in this experiment. By ToF-SIMS surface imaging the deposition trace picture has been obtained. Effluent deposition surface area was scanned for diterpenoic acid fragment mass values based on mass spectrometric library. Measured ToF-SIMS dataset of fragment abundance and intensities were used for preliminary fragmentation schemes construction. The lowest substrate background activity has been established for monolithic silica gel thin layer and aluminium backplate modified Si 60 thin layer. In the case of Raman spectroscopy pre-treated thin layer or conventional chromatographic thin layer Si 60, the both, high background signal intensity and impossibility to construct negative ions surface image, were observed. Diterpenoic acids studied serve the similar mass spectrum but ToF-SIMS coupled with liquid chromatographic separation brings new impact to the positive identification of analytes studied.

  4. Micro-miniature gas chromatograph column disposed in silicon wafers

    DOEpatents

    Yu, Conrad M.

    2000-01-01

    A micro-miniature gas chromatograph column is fabricated by forming matching halves of a circular cross-section spiral microcapillary in two silicon wafers and then bonding the two wafers together using visual or physical alignment methods. Heating wires are deposited on the outside surfaces of each wafer in a spiral or serpentine pattern large enough in area to cover the whole microcapillary area inside the joined wafers. The visual alignment method includes etching through an alignment window in one wafer and a precision-matching alignment target in the other wafer. The two wafers are then bonded together using the window and target. The physical alignment methods include etching through vertical alignment holes in both wafers and then using pins or posts through corresponding vertical alignment holes to force precision alignment during bonding. The pins or posts may be withdrawn after curing of the bond. Once the wafers are bonded together, a solid phase of very pure silicone is injected in a solution of very pure chloroform into one end of the microcapillary. The chloroform lowers the viscosity of the silicone enough that a high pressure hypodermic needle with a thumbscrew plunger can force the solution into the whole length of the spiral microcapillary. The chloroform is then evaporated out slowly to leave the silicone behind in a deposit.

  5. Recent Advances in Water Analysis with Gas Chromatograph Mass Spectrometers

    NASA Technical Reports Server (NTRS)

    MacAskill, John A.; Tsikata, Edem

    2014-01-01

    We report on progress made in developing a water sampling system for detection and analysis of volatile organic compounds in water with a gas chromatograph mass spectrometer (GCMS). Two approaches are described herein. The first approach uses a custom water pre-concentrator for performing trap and purge of VOCs from water. The second approach uses a custom micro-volume, split-splitless injector that is compatible with air and water. These water sampling systems will enable a single GC-based instrument to analyze air and water samples for VOC content. As reduced mass, volume, and power is crucial for long-duration, manned space-exploration, these water sampling systems will demonstrate the ability of a GCMS to monitor both air and water quality of the astronaut environment, thereby reducing the amount of required instrumentation for long duration habitation. Laboratory prototypes of these water sampling systems have been constructed and tested with a quadrupole ion trap mass spectrometer as well as a thermal conductivity detector. Presented herein are details of these water sampling system with preliminary test results.

  6. Chromatographic separation of germanium and arsenic for the production of high purity (77)As.

    PubMed

    Gott, Matthew D; DeGraffenreid, Anthony J; Feng, Yutian; Phipps, Michael D; Wycoff, Donald E; Embree, Mary F; Cutler, Cathy S; Ketring, Alan R; Jurisson, Silvia S

    2016-04-01

    A simple column chromatographic method was developed to isolate (77)As (94±6% (EtOH/HCl); 74±11 (MeOH)) from germanium for potential use in radioimmunotherapy. The separation of arsenic from germanium was based on their relative affinities for different chromatographic materials in aqueous and organic environments. Using an organic or mixed mobile phase, germanium was selectively retained on a silica gel column as germanate, while arsenic was eluted from the column as arsenate. Subsequently, enriched (76)Ge (98±2) was recovered for reuse by elution with aqueous solution (neutral to basic). Greater than 98% radiolabeling yield of a (77)As-trithiol was observed from methanol separated [(77)As]arsenate [17]. PMID:26947162

  7. Optimization of an improved single-column chromatographic process for the separation of enantiomers.

    PubMed

    Kazi, Monzure-Khoda; Medi, Bijan; Amanullah, Mohammad

    2012-03-30

    This work addresses optimization of an improved single-column chromatographic (ISCC) process for the separation of guaifenesin enantiomers. Conventional feed injection and fraction collection systems have been replaced with customized components facilitating simultaneous separation and online monitoring with the ultimate objective of application of an optimizing controller. Injection volume, cycle time, desorbent flow rate, feed concentration, and three cut intervals are considered as decision variables. A multi-objective optimization technique based on genetic algorithm (GA) is adopted to achieve maximum productivity and minimum desorbent requirement in the region constrained by product specifications and hardware limitations. The optimization results along with the contribution of decision variables are discussed using Pareto fronts that identify non-dominated solutions. Optimization results of a similar simulated moving bed process have also been included to facilitate comparison with a continuous chromatographic process. PMID:22364669

  8. Ion-exchange chromatographic separation of anions on hydrated bismuth oxide impregnated papers

    SciTech Connect

    Dabral, S.K.; Muktawat, K.P.S.; Rawat, J.P.

    1988-04-01

    A comparative study of the chromatographic behavior of anions, iodide, sulfide, phosphate, arsenate, arsenite, vanadate, chromate, dichromate, thiosulfate, thiocyanate, ferricyanide and ferrocyanide on papers impregnated with hydrated bismuth oxide and untreated Whatman no.1 paper has been made by employing identical aqueous, non-aqueous and mixed solvent system. Sharp and compact spots were obtained with impregnated papers whereas the opposite applied to plain papers. Various analytically important binary and ternary separations are reported.

  9. Programmed automation of modulator cold jet flow for comprehensive two-dimensional gas chromatographic analysis of vacuum gas oils.

    PubMed

    Rathbun, Wayne

    2007-01-01

    A method is described for automating the regulation of cold jet flow of a comprehensive two-dimensional gas chromatograph (GCxGC) configured with flame ionization detection. This new capability enables the routine automated separation, identification, and quantitation of hydrocarbon types in petroleum fractions extending into the vacuum gas oil (VGO) range (IBP-540 degrees C). Chromatographic data acquisition software is programmed to precisely change the rate of flow from the cold jet of a nitrogen cooled loop modulator of a GCxGC instrument during sample analysis. This provides for the proper modulation of sample compounds across a wider boiling range. The boiling point distribution of the GCxGC separation is shown to be consistent with high temperature simulated distillation results indicating recovery of higher boiling semi-volatile VGO sample components. GCxGC configured with time-of-flight mass spectrometry is used to determine the molecular identity of individual sample components and boundaries of different molecular types. PMID:18078570

  10. Absolutely Exponential Stability and Temperature Control for Gas Chromatograph System Under Dwell Time Switching Techniques.

    PubMed

    Sun, Xi-Ming; Wang, Xue-Fang; Tan, Ying; Wang, Xiao-Liang; Wang, Wei

    2016-06-01

    This paper provides a design strategy for temperature control of the gas chromatograph. Usually gas chromatograph is modeled by a simple first order system with a time-delay, and a proportion integration (PI) controller is widely used to regulate the output of the gas chromatograph to the desired temperature. As the characteristics of the gas chromatograph varies at the different temperature range, the single-model based PI controller cannot work well when output temperature varies from one range to another. Moreover, the presence of various disturbance will further deteriorate the performance. In order to improve the accuracy of the temperature control, multiple models are used at the different temperature ranges. With a PI controller designed for each model accordingly, a delay-dependent switching control scheme using the dwell time technique is proposed to ensure the absolute exponential stability of the closed loop. Experiment results demonstrate the effectiveness of the proposed switching technique. PMID:26316283

  11. Miniaturized gas chromatograph-Paul ion trap system: applications to environmental monitoring

    NASA Technical Reports Server (NTRS)

    Shortt, B. J.; Darrach, M. R.; Holland, Paul M.; Chutjian, A.

    2004-01-01

    A miniature gas chromatograph (GC) and miniature Paul ion trap (PT) mass spectrometer system has been developed for identifying and quantifying chemical species present in closed environments having a complex mixture of gases.

  12. Application of Sigmoidal Transformation Functions in Optimization of Micellar Liquid Chromatographic Separation of Six Quinolone Antibiotics.

    PubMed

    Hadjmohammadi, Mohammadreza; Salary, Mina

    2016-03-01

    A chemometrics approach has been used to optimize the separation of six quinolone compounds by micellar liquid chromatography (MLC). A Derringer's desirability function, a multicriteria decision-making (MCDM) method, was tested for evaluation of two different measures of chromatographic performance (resolution and analysis time). The effect of three experimental parameters on a chromatographic response function (CRF) expressed as a product of two sigmoidal desirability functions was investigated. The sigmoidal functions were used to transform the optimization criteria, resolution and analysis time into the desirability values. The factors studied were the concentration of sodium dodecyl sulfate, butanol content and pH of the mobile phase. The experiments were done according to the face-centered cube central composite design, and the calculated CRF values were fitted to a polynomial model to correlate the CRF values with the variables and their interactions. The developed regression model showed good descriptive and predictive ability (R(2) = 0.815, F = 6.919, SE = 0.038, [Formula: see text]) and used, by a grid search algorithm, to optimize the chromatographic conditions for the separation of the mixture. The efficiency of prediction of polynomial model was confirmed by performing the experiment under the optimal conditions. PMID:26590234

  13. Gas Separations using Ceramic Membranes

    SciTech Connect

    Paul KT Liu

    2005-01-13

    This project has been oriented toward the development of a commercially viable ceramic membrane for high temperature gas separations. A technically and commercially viable high temperature gas separation membrane and process has been developed under this project. The lab and field tests have demonstrated the operational stability, both performance and material, of the gas separation thin film, deposited upon the ceramic membrane developed. This performance reliability is built upon the ceramic membrane developed under this project as a substrate for elevated temperature operation. A comprehensive product development approach has been taken to produce an economically viable ceramic substrate, gas selective thin film and the module required to house the innovative membranes for the elevated temperature operation. Field tests have been performed to demonstrate the technical and commercial viability for (i) energy and water recovery from boiler flue gases, and (ii) hydrogen recovery from refinery waste streams using the membrane/module product developed under this project. Active commercializations effort teaming with key industrial OEMs and end users is currently underway for these applications. In addition, the gas separation membrane developed under this project has demonstrated its economical viability for the CO2 removal from subquality natural gas and landfill gas, although performance stability at the elevated temperature remains to be confirmed in the field.

  14. Sensitive gas chromatographic detection of acetaldehyde and acetone using a reduction gas detector

    NASA Technical Reports Server (NTRS)

    O'Hara, Dean; Singh, Hanwant B.

    1988-01-01

    The response of a newly available mercuric oxide Reduction Gas Detector (RGD-2) to subpicomole and larger quantities of acetaldehyde and acetone is tested. The RGD-2 is found to be capable of subpicomole detection for these carbonyls and is more sensitive than an FID (Flame Ionization Detector) by an order of magnitude. Operating parameters can be further optimized to make the RGD-2 some 20-40 times more sensitive than an FID. The detector is linear over a wide range and is easily adapted to a conventional gas chromatograph (GC). Such a GC-RGD-2 system should be suitable for atmospheric carbonyl measurements in clean as well as polluted environments.

  15. Extraction chromatographic separation of Am(III) and Eu(III) by TPEN-immobilized gel

    SciTech Connect

    Takeshita, K.; Ogata, T.; Oaki, H.; Inaba, Y.; Mori, A.; Yaita, T.; Koyama, S.I.

    2013-07-01

    A TPEN derivative with 4 vinyl groups, N,N,N',N' -tetrakis-(4-propenyloxy-2-pyridylmethyl)ethylenediamine (TPPEN) was synthesized for the separation of trivalent minor actinides (Am(III)) and lanthanides (Eu(III)). A co-polymer gel with TPPEN and N-isopropylacrylamide (NIPA) showed a high separation factor of Am(III) over Eu(III) (SF[Am/Eu]), which was evaluated to be 26 at pH=5. Thin film of NIPA-TPPEN gel (average thickness: 2-40 nm) was immobilized on the pore surface in porous silica particles (particle diameter : 50 μm, average pore diameter : 50 and 300 nm) and a chromatographic column (diameter: 6 mm, height: 11 mm) packed with the gel-coated particles was prepared. A small amount of weakly acidic solution (pH=4) containing Am(III) and Eu(III) was supplied in the column and the elution tests of Am(III) and Eu(III) were carried out. Eu(III) was recovered separately by a weakly acidic eluent (pH=4) at 313 K and Am(III) by a highly acidic eluent (pH=2) at 298 K. These results suggest that the contentious separation of minor actinides and lanthanides is attainable by a new extraction chromatographic process with two columns adjusted to 298 K and 313 K. (authors)

  16. Metal-organic frameworks for analytical chemistry: from sample collection to chromatographic separation.

    PubMed

    Gu, Zhi-Yuan; Yang, Cheng-Xiong; Chang, Na; Yan, Xiu-Ping

    2012-05-15

    In modern analytical chemistry researchers pursue novel materials to meet analytical challenges such as improvements in sensitivity, selectivity, and detection limit. Metal-organic frameworks (MOFs) are an emerging class of microporous materials, and their unusual properties such as high surface area, good thermal stability, uniform structured nanoscale cavities, and the availability of in-pore functionality and outer-surface modification are attractive for diverse analytical applications. This Account summarizes our research on the analytical applications of MOFs ranging from sampling to chromatographic separation. MOFs have been either directly used or engineered to meet the demands of various analytical applications. Bulk MOFs with microsized crystals are convenient sorbents for direct application to in-field sampling and solid-phase extraction. Quartz tubes packed with MOF-5 have shown excellent stability, adsorption efficiency, and reproducibility for in-field sampling and trapping of atmospheric formaldehyde. The 2D copper(II) isonicotinate packed microcolumn has demonstrated large enhancement factors and good shape- and size-selectivity when applied to on-line solid-phase extraction of polycyclic aromatic hydrocarbons in water samples. We have explored the molecular sieving effect of MOFs for the efficient enrichment of peptides with simultaneous exclusion of proteins from biological fluids. These results show promise for the future of MOFs in peptidomics research. Moreover, nanosized MOFs and engineered thin films of MOFs are promising materials as novel coatings for solid-phase microextraction. We have developed an in situ hydrothermal growth approach to fabricate thin films of MOF-199 on etched stainless steel wire for solid-phase microextraction of volatile benzene homologues with large enhancement factors and wide linearity. Their high thermal stability and easy-to-engineer nanocrystals make MOFs attractive as new stationary phases to fabricate MOF

  17. Gas separations using inorganic membranes

    SciTech Connect

    Egan, B.Z.; Singh, S.P.N.; Fain, D.E.; Roettger, G.E.; White, D.E.

    1992-04-01

    This report summarizes the results from a research and development program to develop, fabricate, and evaluate inorganic membranes for separating gases at high temperatures and pressures in hostile process environments encountered in fossil energy conversion processes such as coal gasification. The primary emphasis of the research was on the separation and recovery of hydrogen from synthesis gas. Major aspects of the program included assessment of the worldwide research and development activity related to gas separations using inorganic membranes, identification and selection of candidate membrane materials, fabrication and characterization of membranes using porous membrane technology developed at the Oak Ridge K-25 Site, and evaluation of the separations capability of the fabricated membranes in terms of permeabilities and fluxes of gases.

  18. Microfabricated silicon gas chromatographic micro-channels: fabrication and performance

    SciTech Connect

    Matzke, C.M.; Kottenstette, R.J.; Casalnuovo, S.A.; Frye-Mason, G.C.; Hudson, M.L.; Sasaki, D.Y.; Manginell, R.P.; Wong, C.C.

    1998-11-01

    Using both wet and plasma etching, we have fabricated micro-channels in silicon substrates suitable for use as gas chromatography (GC) columns. Micro-channel dimensions range from 10 to 80 {micro}m wide, 200 to 400 {micro}m deep, and 10 cm to 100 cm long. Micro-channels 100 cm long take up as little as 1 cm{sup 2} on the substrate when fabricated with a high aspect ratio silicon etch (HARSE) process. Channels are sealed by anodically bonding Pyrex lids to the Si substrates. We have studied micro-channel flow characteristics to establish model parameters for system optimization. We have also coated these micro-channels with stationary phases and demonstrated GC separations. We believe separation performance can be improved by increasing stationary phase coating uniformity through micro-channel surface treatment prior to stationary phase deposition. To this end, we have developed microfabrication techniques to etch through silicon wafers using the HARSE process. Etching completely through the Si substrate facilitates the treatment and characterization of the micro- channel sidewalls, which domminate the GC physico-chemical interaction. With this approach, we separately treat the Pyrex lid surfaces that form the top and bottom surfaces of the GC flow channel.

  19. Microfabricated silicon gas chromatographic microchannels: fabrication and performance

    NASA Astrophysics Data System (ADS)

    Matzke, Carolyn M.; Kottenstette, Richard J.; Casalnuovo, Stephen A.; Frye-Mason, Gregory C.; Hudson, Mary L.; Sasaki, Darryl Y.; Manginell, Ronald P.; Wong, C. Channy

    1998-08-01

    Using both wet and plasma etching, we have fabricated micro- channels in silicon substrates suitable for use as gas chromatography (GC) columns. Micro-channel dimensions range from 10 to 80 micrometer wide, 200 to 400 micrometer deep, and 10 cm to 100 cm long. Micro-channels 100 cm long take up as little as 1 cm2 on the substrate when fabricated with a high aspect ratio silicon etch (HARSE) process. Channels are sealed by anodically bonding Pyrex lids to the Si substrates. We have studied micro-channel flow characteristics to establish model parameters for system optimization. We have also coated these micro-channels with stationary phases and demonstrated GC separations. We believe separation performance can be improved by increasing stationary phase coating uniformity through micro-channel surface treatment prior to stationary phase deposition. To this end, we have developed microfabrication techniques to etch through silicon wafers using the HARSE process. Etching completely through the Si substrate facilitates the treatment and characterization of the micro-channel sidewalls, which dominate the GC physico- chemical interaction. With this approach, we separately treat the Pyrex lid surfaces that form the top and bottom surfaces of the GC flow channel.

  20. A trade off between separation, detection and sustainability in liquid chromatographic fingerprinting.

    PubMed

    Funari, Cristiano S; Carneiro, Renato L; Cavalheiro, Alberto J; Hilder, Emily F

    2014-08-01

    It is now recognized that analytical chemistry must also be a target for green principles, in particular chromatographic methods which typically use relatively large volumes of hazardous organic solvents. More generally, high performance liquid chromatography (HPLC) is employed routinely for quality control of complex mixtures in various industries. Acetonitrile and methanol are the most commonly used organic solvents in HPLC, but they generate an impact on the environment and can have a negative effect on the health of analysts. Ethanol offers an exciting alternative as a less toxic, biodegradable solvent for HPLC. In this work we demonstrate that replacement of acetonitrile with ethanol as the organic modifier for HPLC can be achieved without significantly compromising analytical performance. This general approach is demonstrated through the specific example analysis of a complex plant extract. A benchmark method employing acetonitrile for the analysis of Bidens pilosa extract was statistically optimized using the Green Chromatographic Fingerprinting Response (GCFR) which includes factors relating to separation performance and environmental parameters. Methods employing ethanol at 30 and 80°C were developed and compared with the reference method regarding their performance of separation (GCFR) as well as by a new metric, Comprehensive Metric to Compare Liquid Chromatography Methods (CM). The fingerprint with ethanol at 80°C was similar to or better than that with MeCN according to GCFR and CM. This demonstrates that temperature may be used to replace harmful solvents with greener ones in HPLC, including for solvents with significantly different physiochemical properties and without loss in separation performance. This work offers a general approach for the chromatographic analysis of complex samples without compromising green analytical chemistry principles. PMID:24952659

  1. LIQUID CHROMATOGRAPHIC SEPARATION OF THE ENANTIOMERS OF TRANS-CHLORDANE, CIS-CHLORDANE, HEPTACHLOR, HEPTACHLOR EPOXIDE AND ALPHA-HEXACHLOROCYCLOHEXANE WITH APPLICATION TO SMALL-SCALE PREPARATIVE SEPARATION

    EPA Science Inventory

    Analytical high-performance liquid chromatographic separations of the individual enantiomers of five polychlorinated compounds were obtained on polysaccharide stereoselective HPLC columns. The enantiomers of the pesticides trans-chlordane, cis-chlordane and heptachlor were separa...

  2. [Development of online conventional array-based two-dimensional liquid chromatographic system for proteins separation in human plasma].

    PubMed

    Huang, Zhi; Hong, Guangfeng; Gao, Mingxia; Zhang, Xiangmin

    2014-04-01

    Human plasma is one of the proteins-containing samples most difficult to characterize on account of the wide dynamic concentration range of its intact proteins. Herein, we developed a high-throughput conventional array-based two-dimensional liquid chromatographic system for proteins separation in human plasma in online mode. In the system, a conventional strong-anion exchange chromatographic column was used as the first separation dimension and eight parallel conventional reversed-phase liquid chromatographic columns were integrated as the second separation dimension. The fractions from the first dimension were sequentially transferred into the corresponding reversed-phase liquid chromatographic precolumns for retention and enrichment using a 10-port electrically actuated multi-position valve. The second dimensional solvent flow was directly and identically split into 8 channels. The fractions were concurrently back-flushed from the precolumns into the 8 conventional RP columns and were separated simultaneously. An 8-channel fraction collector was refitted to collect the reversed-phase liquid chromatographic fractions for further investigation. Bicinchoninic acid (BCA) dyein solution was conveniently used for high-abundance protein location. Two separation dimensions were relatively independent parts, as well as each channel of the second dimensional array separation. Therefore, the new system could improve the separation throughput and total peak capacity. The system was successfully applied for the separation of human plasma intact proteins. The results indicated the established system is an effective method for removing high abundance proteins in plasma and in-depth research in plasma proteomics. PMID:25069321

  3. Chromatographic separation of phenylpropanol enantiomers on a quinidine carbamate-type chiral stationary phase

    SciTech Connect

    Asnin, Leonid; Guiochon, Georges A

    2005-07-01

    The retention and the separation of the enantiomers of 1-phenylpropanol (1PP), 2-phenylpropanol (2PP), and 3-chloro-1-phenylpropanol (3CPP) on silica-bonded quinidine carbamate under normal phase HPLC conditions were investigated. A relatively high selectivity of the stationary phase for 3CPP and 1PP ({alpha} {approx} 1.07-1.09) was achieved with eluents containing ethyl acetate as the polar modifier. These mobile phases were examined in detail. Based on the set of chromatographic and thermodynamic data collected, conclusions regarding the mechanism of enantioselectivity and the structure of the selector chiral center are made.

  4. Clickable Periodic Mesoporous Organosilica Monolith for Highly Efficient Capillary Chromatographic Separation.

    PubMed

    Wu, Ci; Liang, Yu; Yang, Kaiguang; Min, Yi; Liang, Zhen; Zhang, Lihua; Zhang, Yukui

    2016-02-01

    A novel clickable periodic mesoporous organosilica monolith with the surface area up to 1707 m(2) g(-1) was in situ synthesized in the capillary by the one-step condensation of the organobridged-bonded alkoxysilane precursor bis(triethoxysilyl)ethylene. With Si-C bonds in the skeleton, the monolith possesses excellent chemical and mechanical stability. With vinyl groups highly loaded and homogeneously distributed throughout the structure, the monolith can be readily functionalized with functional groups by effective thiol-ene "click" chemistry reaction. Herein, with "click" modification of C18, the obtained monolith was successfully applied for capillary liquid chromatographic separation of small molecules and proteins. The column efficiency could reach 148,000 N/m, higher than most reported hybrid monoliths. Moreover, intact proteins could be separated well with good reproducibility, even after the monolithic column was exposed by basic mobile phase (pH 10.0) overnight, demonstrating the great promising of such monolith for capillary chromatographic separation. PMID:26751092

  5. High-resolution gas chromatographic profiles of volatile organic compounds produced by microorganisms at refrigerated temperatures.

    PubMed Central

    Lee, M L; Smith, D L; Freeman, L R

    1979-01-01

    Three different strains of bacteria isolated from spoiled, uncooked chicken were grown in pure culture on Trypticase soy agar supplemented with yeast extract. The volatile organic compounds produced by each culture were concentrated on a porous polymer precolumn and analyzed by high-resolution gas chromatographic mass spectrometry. Twenty different compounds were identified. Both qualitative and quantitative differences in the chromatographic profiles from each culture were found. PMID:104660

  6. Efficient method development strategy for challenging separation of pharmaceutical molecules using advanced chromatographic technologies.

    PubMed

    Xiao, Kang Ping; Xiong, Yuan; Liu, Fang Zhu; Rustum, Abu M

    2007-09-01

    In this paper, we describe a strategy that can be used to efficiently develop a high-performance liquid chromatography (HPLC) separation of challenging pharmaceutical molecules. This strategy involves use of advanced chromatographic technologies, such as a computer-assisted chromatographic method development tool (ChromSword) and an automated column switching system (LC Spiderling). This process significantly enhances the probability of achieving adequate separations and can be a large time saver for bench analytical scientists. In our study, the ChromSword was used for mobile phase screening and separation optimization, and the LC Spiderling was used to identify the most appropriate HPLC columns. For proof of concept, the analytes employed in this study are the structural epimers betamethylepoxide and alphamethylepoxide (also known as 16-beta methyl epoxide and 16-alpha methyl epoxide). Both of these compounds are used in the synthesis of various active pharmaceutical ingredients that are part of the steroid pharmaceutical products. While these molecules are relatively large in size and contain various polar functional groups and non-polar cyclic carbon chains, their structures differ only in the orientation of one methyl group. To our knowledge, there is no reported HPLC separation of these two molecules. A simple gradient method was quickly developed on a 5 cm YMC Hydrosphere C(18) column that separated betamethylepoxide and alphamethylepoxide in 10 min with a resolution factor of 3.0. This high resolution provided a true baseline separation even when the concentration ratio between these two epimers was 10,000:1. Although outside of the scope of this paper, stability-indicating assay and impurity profile methods for betamethylepoxide and for alphamethylepoxide have also been developed by our group based on a similar method development strategy. PMID:17628579

  7. Phosphazene membranes for gas separations

    DOEpatents

    Stewart, Frederick F.; Harrup, Mason K.; Orme, Christopher J.; Luther, Thomas A.

    2006-07-11

    A polyphosphazene having a glass transition temperature ("T.sub.g") of approximately -20.degree. C. or less. The polyphosphazene has at least one pendant group attached to a backbone of the polyphosphazene, wherein the pendant group has no halogen atoms. In addition, no aromatic groups are attached to an oxygen atom that is bound to a phosphorus atom of the backbone. The polyphosphazene may have a T.sub.g ranging from approximately -100.degree. C. to approximately -20.degree. C. The polyphosphazene may be selected from the group consisting of poly[bis-3-phenyl-1-propoxy)phosphazene], poly[bis-(2-phenyl-1-ethoxy)phosphazene], poly[bis-(dodecanoxypolyethoxy)-phosphazene], and poly[bis-(2-(2-(2-.omega.-undecylenyloxyethoxy)ethoxy)ethoxy)phosphazene]- . The polyphosphazene may be used in a separation membrane to selectively separate individual gases from a gas mixture, such as to separate polar gases from nonpolar gases in the gas mixture.

  8. Green Chromatographic Separation of Coumarin and Vanillins Using Subcritical Water as the Mobile Phase.

    PubMed

    Kayan, Berkant; Akay, Sema; Yang, Yu

    2016-08-01

    Pure water was used as the eluent for separation of coumarin, vanillin and ethyl vanillin at temperatures ranging from 100 to 200°C using a homemade subcritical water chromatography (SBWC) system. Chromatographic separations were performed on five commercial columns including XTerra MS C18, XBridge C18, Zorbax RRHD Eclipse Plus, Zorbax SB-Phenyl and Zorbax SB-C18 columns. The retention time of all three solutes decreased with increasing water temperature. The shortest retention time among all acceptable separations, less than 4 min, was achieved on the Zorbax SB-C18 column at 200°C. While separations on the XTerra MS C18 column resulted in fronting peaks and a degradation peak from ethyl vanillin on the Zorbax RRHD Eclipse Plus column was observed, all three other columns yielded reasonable separations under SBWC conditions. In addition to separation of the standard test mixture, separation of coumarin contained in a skincare cream sample was also carried out using SBWC. PMID:27060112

  9. Gas chromatograph-based system for measuring the methane fraction of diesel-engine hydrocarbon emissions

    SciTech Connect

    Hoffman, J.S.; Geyer, S.M.; Lestz, S.S.; Black, F.M.

    1987-03-01

    An instrument has been developed (termed the methane analytical system) enabling diesel methane emissions to be quatified separately from total unburned hydrocarbon emissions. The instrument employed gas-chromatographic principles whereby a molecular-sieve column operating isothermally separated methane from the nonmethane hydrocarbons. Direct on-line sampling occurred via constant-volume sample loops. The effluent was monitored with a flame ionization detector. The instrument was fully calibrated (i.e., extremely linear response over a large concentration range) for use with diesel engines as part of an on-going alternative-fuels research program. Methane emissions from a light-duty, multi-cylinder, indirect-injected diesel engine fumigated with natural gas were measured on-line using the methane analytical system. Methane emissions were found to range from as low as 250 ppm to a high of nearly 2%. The nonmethane hydrocarbon emissions were determined by subtracting the methane level from the total unburned hydrocarbon level. In the event that the federal engine certification procedures are changed to be based on nonmethane hydrocarbon emissions, a methane analytical system such as the one described here would have great utility.

  10. Extraction chromatographic separation of promethium from high active waste solutions of Purex origin

    SciTech Connect

    Ramanujam, A.; Achuthan, P.V.; Dhami, P.S.; Gopalakrishnan, V.; Kannan, R.; Mathur, J.N.

    1995-03-01

    An extraction chromatographic procedure for the separation of {sup 147}Pm from High Active Waste solutions of Purex process has been developed. Octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide(CMPO) and 2-ethylhexyl-2-ethylhexylphosphonic acid (KSM-17), both sorbed separately on an inert support(chromosorb-102) have been sequentially employed for this purpose. In the CMPO column, the rare earths and the trivalent actinides are sorbed together with uranium, plutonium and traces of few other fission products. The elution of this column with 0.04 M HNO{sub 3} gives an eluate containing trivalent actinides and lanthanides. This solution, after adjusting the pH to 2.0, is used as feed for the second extraction chromatographic column based on KSM-17. All the trivalent metal ions are sorbed on the column leaving the trace impurities in the effluent. Fractional elution of the metal ions from this column is carried out with nitric acid of varying concentrations. At 0.09 M HNO{sub 3}, the pure beta emitting fraction of {sup 147}Pm has been obtained. 16 refs., 3 figs., 2 tabs.

  11. Dried calcium alginate/magnetite spheres: a new support for chromatographic separations and enzyme immobilization

    SciTech Connect

    Burns, M.A.; Kvesitadze, G.I.; Graves, D.J.

    1985-02-01

    Dried spheres made from an alginate solution containing magnetite particles have excellent potential as a support for enzyme immobilization and chromatographic applications. The beads were found to be much stronger than gels such as polyacrylamide and dextran, indicating that high flow rates and pressures could be used in column separations. The support withstood not only temperatures of up to 120/sup 0/C, but also most pH values and common solvents. While some solutions, such as phosphate buffers, dissolved the spheres, stabilization with Tyzor TE eliminated this problem. The physical properties of the beads include a glasslike density of 2.2 g/mL, excellent sphericity, low porosity, and a narrow size distribution. The magnetite present in the support allows the beads to be used for magnetic separations such as high gradient magnetic filtration. Their high degree of microroughness provides a large exposed surface area for enzyme and ligand binding. Mixed Actinomyces fradiae proteases and Aspergillus niger ..cap alpha..-amylase, two enzymes representative of classes which attack large substrates, were immobilized on the bead's surface with high activity and stability. A cyanuric dye which can be used in chromatographic applications (Cibacron Blue F3GA) was also readily coupled to the surface of this support with good yield.

  12. Gas chromatographic determination of the interconversion energy barrier for dialkyl 2,3-pentadienedioate enantiomers.

    PubMed

    Mydlová, J; Krupcík, J; Májek, P; Skacáni, I; Jakubík, T; Sandra, P; Armstrong, D W

    2007-05-25

    The enantiomers of dialkyl 2,3-pentadienedioate undergo interconversion during gas chromatographic separation on chiral stationary phases. In this paper the on-column apparent interconversion kinetic and thermodynamic activation data were determined for dimethyl, diethyl, propylbutyl and dibutyl 2,3-pentadienedioate enantiomers by gas chromatographic separation of the racemic mixtures on a capillary column containing a polydimethylsiloxane stationary phase coupled to 2,3-di-O-methyl-6-O-tertbutyldimethylsilyl-beta-cyclodextrin. A deconvolution method was used to determine the individual enantiomer peak areas and retention times that are needed to calculate the interconversion rate constants and the energy barriers. The apparent rate constants and interconversion energy barriers decrease slightly with an increase in the alkyl chain length of the dialkyl 2,3-pentadienedioate esters. The optimum conformation of the dialkyl 2,3-pentadienedioate molecules, their separation selectivity factors and apparent interconversion enthalpy and entropy data changes with the alkyl chain length. The dependence of the apparent interconversion energy barrier (deltaG(app)(a-->b), deltaG(app)(b-->a)) on temperature was used to determine the apparent activation enthalpy (deltaH(app)(a-->b), deltaH(app)(b-->a)) and apparent entropy (deltaS(app)(a-->b), deltaS(app)(a-->b)) (where a denotes the first and b second eluted enantiomer). The comparison of the activation enthalpy and entropy (deltaS(app)(a-->b), deltaS(app)(a-->b)) indicated that the interconversion of dialkyl 2,3-pentadienedioate enantiomers on the HP-5+Chiraldex B-DM column series is an entropy driven process at 160 degrees C. Data obtained for dimethyl 2,3-pentadienedioate enantiomers on the HP-5+Chiraldex B-DM column series at 120 degrees C (deltaG(app)(a-->b) = 123.3 and deltaG(app)(b-->a) = 124.4 kJ mol(-1)) corresponds (at the 95% confidence interval) with the value of deltaG(#) = 128+/-1 kJ mol(-1) found at this

  13. Novel behavior of the chromatographic separation of linear and cyclic polymers.

    PubMed

    Montenegro-Burke, J Rafael; Bennett, Jackson M; McLean, John A; Hercules, David M

    2016-01-01

    In various polymerization processes, the formation of a wide variety of chains, not only in length but also in chemical composition, broadly complicates comprehensive polymer characterization. In this communication, we compare different stationary and mobile phases for the analysis of complex polymer mixtures via size-exclusion chromatography-mass spectrometry (SEC-MS). To the best of our knowledge, we report novel chromatographic effects for the separation of linear and cyclic oligomers for polyesters (PE) and polyurethanes (PUR). A complete separation for the different structures was achieved for both polymer types with a single-solvent system (acetonitrile, ACN) and without extensive optimization. Additionally, cyclic species were found to show an inverse elution profile compared to their linear counterparts, suggesting distinct physical properties between species. PMID:26637218

  14. In situ sol-gel preparation of porous alumina monoliths for chromatographic separations of adenosine phosphates.

    PubMed

    Zajickova, Zuzana; Rubi, Emir; Svec, Frantisek

    2011-06-01

    A method enabling the in situ preparation of porous alumina monoliths within 100 μm i.d. fused silica capillaries has been developed. These monoliths were prepared using the sol-gel process from a mixture consisting of an inorganic aluminum salt, a porogen, an epoxide, and a solvent. We investigated the effects of varying the preparation conditions on the physical characteristics of the monoliths with respect to their potential application in chromatographic separations. The best columns were obtained from a mixture of aluminum chloride hexahydrate, N,N-dimethylformamide, water, ethanol and propylene oxide. Adenosine phosphates were then separated in the optimized column with retention increasing according to number of phosphate functionalities. PMID:21497822

  15. Gas chromatographic techniques for the analysis of hydrocarbons in low-rank coal liquefaction products. Part II. Instrumental aspects

    SciTech Connect

    Raynie, D.E.; Farnum, S.A.; Potts, Y.R.

    1984-01-01

    Two long Continuous Processing Unit (CPU) runs were carried out to: (1) study the effect of two different start-up solvents on the composition of the recycle product; and (2) thoroughly characterize any change caused by the start-up solvent during the recycle process. Capillary gas chromatography has been chosen as the major analytical tool in these line-out studies of coal liquefaction products. Initial separations of distillate oils from CPU passes were carried out by the silical gel chromatographic method previously reported. The resulting hydrocarbon fractions were combined into four groups for gas chromatographic analysis. The four groups were chromatographed against the appropriate calibration mixture. Some components of the distillate oil were identified but not quantified due to insufficient amounts of some standards. Over 300 samples also necessitated the use of up to 30 components in a calibration standard. Resulting chromatograms showed near-ideal peak shapes. Peak areas were integrated, ratioed to the internal standard and compared to the appropriate calibration curve. Components were identified by comparing retention times and were confirmed by gas chromatography/mass spectroscopy. Parameters such as threshold, peak width, and baseline construction mode were adjusted for optimum sensitivity. For valid comparisons to be made conditions were carefully reproduced. Although chromatography is not often thought of as an exact science, chromatographic systems can be optimized for a given analytical situation. In this case, we have successfully used capillary gas chromatography for the automated identification and quantification of up to 30 species in a single coal liquefaction fraction. We have quantified 87 compounds in the distillate oil. This method may also serve as the basis for analysis of other complex samples.

  16. New Method for Evaluating Irreversible Adsorption and Stationary Phase Bleed in Gas Chromatographic Capillary Columns

    SciTech Connect

    Wright, Bob W.; Wright, Cherylyn W.

    2012-10-26

    A novel method for the evaluation of gas chromatographic (GC) column inertness has been developed using a tandem GC approach. Typically column inertness is measured by analyte peak shape evaluation. In general, silica, glass, and metal surfaces are chemically reactive and can cause analyte adsorption, which typically is observed as chromatographic peak tailing. Adsorption processes produce broad, short chromatographic peaks that confound peak area determinations because a significant portion can reside in the noise. In addition, chromatographic surfaces and stationary phases can irreversibly adsorb certain analytes without obvious degradation of peak shape. The inertness measurements described in this work specifically determine the degree of irreversible adsorption behavior of specific target compounds at levels ranging from approximately 50 picograms to 1 nanogram on selected gas chromatographic columns. Chromatographic columns with 5% phenylmethylsiloxane, polyethylene glycol (wax), trifluoropropylsiloxane, and 78% cyanopropylsiloxane stationary phases were evaluated with a variety of phosphorus- and sulfur- containing compounds selected as test compounds due to their ease of adsorption and importance in trace analytical detection. In addition, the method was shown effective for characterizing column bleed.

  17. Gas chromatographic column for the storage of sample profiles

    NASA Technical Reports Server (NTRS)

    Dimandja, J. M.; Valentin, J. R.; Phillips, J. B.

    1994-01-01

    The concept of a sample retention column that preserves the true time profile of an analyte of interest is studied. This storage system allows for the detection to be done at convenient times, as opposed to the nearly continuous monitoring that is required by other systems to preserve a sample time profile. The sample storage column is essentially a gas chromatography column, although its use is not the separation of sample components. The functions of the storage column are the selective isolation of the component of interest from the rest of the components present in the sample and the storage of this component as a function of time. Using octane as a test substance, the sample storage system was optimized with respect to such parameters as storage and readout temperature, flow rate through the storage column, column efficiency and storage time. A 3-h sample profile was collected and stored at 30 degrees C for 20 h. The profile was then retrieved, essentially intact, in 5 min at 130 degrees C.

  18. Minimizing thermal degradation in gas chromatographic quantitation of pentaerythritol tetranitrate.

    PubMed

    Lubrano, Adam L; Field, Christopher R; Newsome, G Asher; Rogers, Duane A; Giordano, Braden C; Johnson, Kevin J

    2015-05-15

    An analytical method for establishing calibration curves for the quantitation of pentaerythriol tetranitrate (PETN) from sorbent-filled thermal desorption tubes by gas chromatography with electron capture detection (TDS-GC-ECD) was developed. As PETN has been demonstrated to thermally degrade under typical GC instrument conditions, peaks corresponding to both PETN degradants and molecular PETN are observed. The retention time corresponding to intact PETN was verified by high-resolution mass spectrometry with a flowing atmospheric pressure afterglow (FAPA) ionization source, which enabled soft ionization of intact PETN eluting the GC and subsequent accurate-mass identification. The GC separation parameters were transferred to a conventional GC-ECD instrument where analytical method-induced PETN degradation was further characterized and minimized. A method calibration curve was established by direct liquid deposition of PETN standard solutions onto the glass frit at the head of sorbent-filled thermal desorption tubes. Two local, linear relationships between detector response and PETN concentration were observed, with a total dynamic range of 0.25-25ng. PMID:25841610

  19. Improving Hydrocarbon Separation In Gas Chromatography

    NASA Technical Reports Server (NTRS)

    Pollock, G. E.; Woeller, F.; Kojiro, D. R.

    1983-01-01

    Modified solica spheres enhance chromatographic separation. Commercially available silica spheres are modified by reacting them with molecules containing isocyante and isothiocyanate groups. Applications of surface derivatized spheres that result from reaction include analysis of samples prouced by atmospheric or soil probes.

  20. Liquid chromatographic method for determination of water in soils and the optimization of anion separations by capillary zone electrophoresis

    SciTech Connect

    Benz, N.

    1994-10-01

    A liquid chromatographic method for the determination of water in soil or clay samples is presented. In a separate study, the optimization of electrophoretic separation of alkylated phenolate ions was optimized by varying the pH and acetonitrile concentration of the buffer solutions.

  1. Development and evaluation of a gas chromatographic method for the determination of triazine herbicides in natural water samples

    USGS Publications Warehouse

    Steinheimer, T.R.; Brooks, M.G.

    1984-01-01

    A multi-residue method is described for the determination of triazine herbicides in natural water samples. The technique uses solvent extraction followed by gas chromatographic separation and detection employing nitrogen-selective devices. Seven compounds can be determined simultaneously at a nominal detection limit of 0.1 ??g/L in a 1-litre sample. Three different natural water samples were used for error analysis via evaluation of recovery efficiencies and estimation of overall method precision. As an alternative to liquid-liquid partition (solvent extraction) for removal of compounds of interest from water, solid-phase extraction (SPE) techniques employing chromatographic grade silicas with chemically modified surfaces have been examined. SPE is found to provide rapid and efficient concentration with quantitative recovery of some triazine herbicides from natural water samples. Concentration factors of 500 to 1000 times are obtained readily by the SPE technique.A multi-residue method is described for the determination of triazine herbicides in natural water samples. The technique uses solvent extraction followed by gas chromatographic separation and detection employing nitrogen-selective devices. Seven compounds can be determined simultaneously at a nominal detection limit of 0. 1 mu g/L in a 1-litre sample. As an alternative to liquid-liquid partition (solvent extraction) for removal of compounds of interest from water, solid-phase extraction (SPE) techniques employing chromatographic grade silicas with chemically modified surfaces have been examined. SPE is found to provide rapid and efficient concentration with quantitative recovery of some triazine herbicides from natural water samples. Concentration factors of 500 to 1000 times are obtained readily by the SPE technique.

  2. On-line gas chromatographic analysis of higher alcohol synthesis products from syngas.

    PubMed

    Andersson, Robert; Boutonnet, Magali; Järås, Sven

    2012-07-20

    An on-line gas chromatographic (GC) system has been developed for rapid and accurate product analysis in catalytic conversion of syngas (a mixture of H₂ and CO) to alcohols, so called "higher alcohol synthesis (HAS)". Conversion of syngas to higher alcohols is an interesting second step in the route of converting coal, natural gas and possibly biomass to liquid alcohol fuel and chemicals. The presented GC system and method are developed for analysis of the products formed from syngas using alkali promoted MoS₂ catalysts, however it is not limited to these types of catalysts. During higher alcohol synthesis not only the wanted short alcohols (∼C₂-C₅) are produced, but also a great number of other products in smaller or greater amounts, they are mainly short hydrocarbons (olefins, paraffins, branched, non-branched), aldehydes, esters and ketones as well as CO₂, H₂O. Trace amounts of sulfur-containing compounds can also be found in the product effluent when sulfur-containing catalysts are used and/or sulfur-containing syngas is feed. In the presented GC system, most of them can be separated and analyzed within 60 min without the use of cryogenic cooling. Previously, product analysis in "higher alcohol synthesis" has in most cases been carried out partly on-line and partly off-line, where the light gases (gases at room temp) are analyzed on-line and liquid products (liquid at room temp) are collected in a trap for later analysis off-line. This method suffers from many drawbacks compared to a complete on-line GC system. In this paper an on-line system using an Agilent 7890 gas chromatograph equipped with two flame ionization detectors (FID) and a thermal conductivity detector (TCD), together with an Agilent 6890 with sulfur chemiluminescence dual plasma detector (SCD) is presented. A two-dimensional GC system with Deans switch (heart-cut) and two capillary columns (HP-FFAP and HP-Al₂O₃) was used for analysis of the organic products on the FIDs. Light

  3. Thin-layer chromatographic (TLC) separations and bioassays of plant extracts to identify antimicrobial compounds.

    PubMed

    Kagan, Isabelle A; Flythe, Michael D

    2014-01-01

    A common screen for plant antimicrobial compounds consists of separating plant extracts by paper or thin-layer chromatography (PC or TLC), exposing the chromatograms to microbial suspensions (e.g. fungi or bacteria in broth or agar), allowing time for the microbes to grow in a humid environment, and visualizing zones with no microbial growth. The effectiveness of this screening method, known as bioautography, depends on both the quality of the chromatographic separation and the care taken with microbial culture conditions. This paper describes standard protocols for TLC and contact bioautography with a novel application to amino acid-fermenting bacteria. The extract is separated on flexible (aluminum-backed) silica TLC plates, and bands are visualized under ultraviolet (UV) light. Zones are cut out and incubated face down onto agar inoculated with the test microorganism. Inhibitory bands are visualized by staining the agar plates with tetrazolium red. The method is applied to the separation of red clover (Trifolium pratense cv. Kenland) phenolic compounds and their screening for activity against Clostridium sticklandii, a hyper ammonia-producing bacterium (HAB) that is native to the bovine rumen. The TLC methods apply to many types of plant extracts and other bacterial species (aerobic or anaerobic), as well as fungi, can be used as test organisms if culture conditions are modified to fit the growth requirements of the species. PMID:24747583

  4. Thin-layer Chromatographic (TLC) Separations and Bioassays of Plant Extracts to Identify Antimicrobial Compounds

    PubMed Central

    Kagan, Isabelle A.; Flythe, Michael D.

    2014-01-01

    A common screen for plant antimicrobial compounds consists of separating plant extracts by paper or thin-layer chromatography (PC or TLC), exposing the chromatograms to microbial suspensions (e.g. fungi or bacteria in broth or agar), allowing time for the microbes to grow in a humid environment, and visualizing zones with no microbial growth. The effectiveness of this screening method, known as bioautography, depends on both the quality of the chromatographic separation and the care taken with microbial culture conditions. This paper describes standard protocols for TLC and contact bioautography with a novel application to amino acid-fermenting bacteria. The extract is separated on flexible (aluminum-backed) silica TLC plates, and bands are visualized under ultraviolet (UV) light. Zones are cut out and incubated face down onto agar inoculated with the test microorganism. Inhibitory bands are visualized by staining the agar plates with tetrazolium red. The method is applied to the separation of red clover (Trifolium pratense cv. Kenland) phenolic compounds and their screening for activity against Clostridium sticklandii, a hyper ammonia-producing bacterium (HAB) that is native to the bovine rumen. The TLC methods apply to many types of plant extracts and other bacterial species (aerobic or anaerobic), as well as fungi, can be used as test organisms if culture conditions are modified to fit the growth requirements of the species. PMID:24747583

  5. Chromatographic cation exchange separation of decigram quantities of californium and other transplutonium elements

    SciTech Connect

    Benker, D.E.; Chattin, F.R.; Collins, E.D.; Knauer, J.B.; Orr, P.B.; Ross, R.G.; Wiggins, J.T.

    1981-01-01

    Decigram quantities of highly radioactive transplutonium elements are routinely partitioned at TRU by chromatographic elution from cation resin using AHIB eluents. Batch runs containing up to 200 mg of /sup 252/Cf can be made in about 5 h (2 h to load the feed and 3 h for the elution), with two high-pressure ion exchange columns, a small one for the initial loading of the feed and a large one for the elution. The separations achieved in the column are preserved by routing the column effluent through an alpha detector and using the response from the detector to select appropriate product fractions. The high-pressure ion exchange process has been reliable and relatively easy to operate; therefore it will continue to be used for partitioning transplutonium elements at TRU. 3 figures, 1 table.

  6. Gas Chromatograph Method Optimization Trade Study for RESOLVE: 20-meter Column v. 8-meter Column

    NASA Technical Reports Server (NTRS)

    Huz, Kateryna

    2014-01-01

    RESOLVE is the payload on a Class D mission, Resource Prospector, which will prospect for water and other volatile resources at a lunar pole. The RESOLVE payload's primary scientific purpose includes determining the presence of water on the moon in the lunar regolith. In order to detect the water, a gas chromatograph (GC) will be used in conjunction with a mass spectrometer (MS). The goal of the experiment was to compare two GC column lengths and recommend which would be best for RESOLVE's purposes. Throughout the experiment, an Inficon Fusion GC and an Inficon Micro GC 3000 were used. The Fusion had a 20m long column with 0.25mm internal diameter (Id). The Micro GC 3000 had an 8m long column with a 0.32mm Id. By varying the column temperature and column pressure while holding all other parameters constant, the ideal conditions for testing with each column length in their individual instrument configurations were determined. The criteria used for determining the optimal method parameters included (in no particular order) (1) quickest run time, (2) peak sharpness, and (3) peak separation. After testing numerous combinations of temperature and pressure, the parameters for each column length that resulted in the most optimal data given my three criteria were selected. The ideal temperature and pressure for the 20m column were 95 C and 50psig. At this temperature and pressure, the peaks were separated and the retention times were shorter compared to other combinations. The Inficon Micro GC 3000 operated better at lower temperature mainly due to the shorter 8m column. The optimal column temperature and pressure were 70 C and 30psig. The Inficon Micro GC 3000 8m column had worse separation than the Inficon Fusion 20m column, but was able to separate water within a shorter run time. Therefore, the most significant tradeoff between the two column lengths was peak separation of the sample versus run time. After performing several tests, it was concluded that better

  7. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT, EXPLOSIVES DETECTION TECHNOLOGY, SRI INSTRUMENTS, MODEL 8610C, GAS CHROMATOGRAPH/THERMIONIC IONIZATION DETECTION

    EPA Science Inventory

    The SRI Model 86 1 OC gas chromatograph (GC) is a transportable instrument that can provide on-site analysis of soils for explosives. Coupling this transportable gas chromatograph with a thermionic ionization detector (TID) allows for the determination of explosives in soil matri...

  8. Separative analyses of a chromatographic column packed with a core-shell adsorbent for lithium isotope separation

    SciTech Connect

    Sugiyama, T.; Sugura, K.; Enokida, Y.; Yamamoto, I.

    2015-03-15

    Lithium-6 is used as a blanket material for sufficient tritium production in DT fueled fusion reactors. A core-shell type adsorbent was proposed for lithium isotope separation by chromatography. The mass transfer model in a chromatographic column consisted of 4 steps, such as convection and dispersion in the column, transfer through liquid films, intra-particle diffusion and and adsorption or desorption at the local adsorption sites. A model was developed and concentration profiles and time variation in the column were numerically simulated. It became clear that core-shell type adsorbents with thin porous shell were saturated rapidly relatively to fully porous one and established a sharp edge of adsorption band. This is very important feature because lithium isotope separation requires long-distance development of adsorption band. The values of HETP (Height Equivalent of a Theoretical Plate) for core-shell adsorbent packed column were estimated by statistical moments of the step response curve. The value of HETP decreased with the thickness of the porous shell. A core-shell type adsorbent is, then, useful for lithium isotope separation. (authors)

  9. Evolutionary multi-objective optimization based comparison of multi-column chromatographic separation processes for a ternary separation.

    PubMed

    Heinonen, Jari; Kukkonen, Saku; Sainio, Tuomo

    2014-09-01

    Performance characteristics of two advanced multi-column chromatographic separation processes with discontinuous feed, Multi-Column Recycling Chromatogrphy (MCRC) and Japan Organo (JO), were investigated for a ternary separation using multi-objective optimization with an evolutionary algorithm. Conventional batch process was used as a reference. Fractionation of a concentrated acid hydrolysate of wood biomass into sulfuric acid, monosaccharide, and acetic acid fractions was used as a model system. Comparison of the separation processes was based on selected performance parameters in their optimized states. Flow rates and step durations were taken as decision variables whereas the column configuration and dimensions were fixed. The MCRC process was found to be considerably more efficient than the other processes with respect to eluent consumption. The batch process gave the highest productivity and the JO process the lowest. Both of the multi-column processes gave significantly higher monosaccharide yield than the batch process. When eluent consumption and monosaccharide yield are taken into account together with productivity, the MCRC process was found to be the most efficient in the studied case. PMID:25060000

  10. [Molecular topology study of gas chromatographic retention indices of alkane series].

    PubMed

    Nie, Changming; Dai, Yimin; Wen, Songnian; Li, Zhonghai

    2005-01-01

    The gas chromatographic retention indices can be used to qualify some organic compounds. A new topological index based on distance matrix and branch vertex of the atoms in a molecule is proposed by defining equilibrium electronegativity of atoms in the molecule and coloring atoms in the molecular graph with equilibrium electronegativity, which appears unique to the molecular structures and has excellent structural selectivity. The multivariate linear equations of gas chromatographic retention indices are as follows: I(Squalane) = 23.97842N1 - 3.86562N2 + 0.787379N3 + 42.33061, R = 0.9922, n = 70, S = 13.70405, F = 1396.601; I(SE-30) = 23.83937N1 - 3.5687N2 + 0.939876N3 + 22.11952, R = 0.9919, n = 37, S = 11.96088, F = 668.8781; where the N1, N2 and N3 are a group of topological indices; n, R, S and F are sample number, regression coefficient, residual standard deviation and F-statistic value, respectively. The calculated results by the formulae indicate that the average relative deviations between calculated values and experimental data of gas chromatographic retention indices of alkane series on both squalane (column temperature 50 degrees C) and SE-30 (column temperature 80 degrees C) were all 1.31% and the errors were within experimental deviations. The equations can express well the change rule of the relative gas chromatographic retention indices of alkane series. PMID:15881357

  11. ON-LINE MEASUREMENT OF THE INFRARED SPECTRA OF GAS CHROMATOGRAPHIC ELUENTS

    EPA Science Inventory

    Techniques for increasing the sensitivity of the interface between a gas chromatograph and a rapid-scanning Fourier transform infrared spectrometer (GC-IR) have been developed. A single-beam system, in which a triglycine sulfate (TGS) detector is used to measure the interferogram...

  12. NEAR-CONTINUOUS MEASUREMENT OF HYDROGEN SULFIDE AND CARBONYL SULFIDE BY AN AUTOMATIC GAS CHROMATOGRAPH

    EPA Science Inventory

    An automatic gas chromatograph with a flame photometric detector that samples and analyzes hydrogen sulfide and carbonyl sulfide at 30-s intervals is described. Temperature programming was used to elute trace amounts of carbon disulfide present in each injection from a Supelpak-S...

  13. AN EVALUATION OF THE HEWLETT-PACKARD 5993B GAS CHROMATOGRAPH-MASS SPECTROMETER

    EPA Science Inventory

    This report gives the results of an evaluation of a Hewlett-Packard Model 5993B computerized gas chromatograph/mass spectrometer. The evaluation was done according to the procedures found in EPA research report number EPA-600/4-80-025, 'Performance Tests for the Evaluation of Com...

  14. 40 CFR 1065.267 - Gas chromatograph with a flame ionization detector.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 34 2013-07-01 2013-07-01 false Gas chromatograph with a flame ionization detector. 1065.267 Section 1065.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon...

  15. 40 CFR 1065.267 - Gas chromatograph with a flame ionization detector.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 34 2012-07-01 2012-07-01 false Gas chromatograph with a flame ionization detector. 1065.267 Section 1065.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon...

  16. 40 CFR 1065.267 - Gas chromatograph with a flame ionization detector.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Gas chromatograph with a flame ionization detector. 1065.267 Section 1065.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon...

  17. 1993 FIELD STUDY/DEMONSTRATION OF AUTOMATED GAS CHROMATOGRAPH IN CONNECTICUT AND OTHER LABORATORIES

    EPA Science Inventory

    The objectives of this study were to install, test and demonstrate two automated gas chromatographic (GC) systems to state and regional EPA groups. he two GC systems required no liquid cryogen for operational purposes. he Dynatherm/Hewlett Packard GC system was designed for the m...

  18. Integrated vacuum absorption steam cycle gas separation

    SciTech Connect

    Chen, Shiaguo; Lu, Yonggi; Rostam-Abadi, Massoud

    2011-11-22

    Methods and systems for separating a targeted gas from a gas stream emitted from a power plant. The gas stream is brought into contact with an absorption solution to preferentially absorb the targeted gas to be separated from the gas stream so that an absorbed gas is present within the absorption solution. This provides a gas-rich solution, which is introduced into a stripper. Low pressure exhaust steam from a low pressure steam turbine of the power plant is injected into the stripper with the gas-rich solution. The absorbed gas from the gas-rich solution is stripped in the stripper using the injected low pressure steam to provide a gas stream containing the targeted gas. The stripper is at or near vacuum. Water vapor in a gas stream from the stripper is condensed in a condenser operating at a pressure lower than the stripper to concentrate the targeted gas. Condensed water is separated from the concentrated targeted gas.

  19. Simple gas chromatographic system for analysis of microbial respiratory gases

    NASA Technical Reports Server (NTRS)

    Carle, G. C.

    1972-01-01

    Dual column ambient temperature system, consisting of pair of capillary columns, microbead thermistor detector and micro gas-sampling valve, is used in remote life-detection equipment for space experiments. Performance outweighs advantage gained by utilizing single-column systems to reduce weight, conserve carrier gas and operate at lower power levels.

  20. Derivatization in gas chromatographic determination of phenol and aniline traces in aqueous media

    NASA Astrophysics Data System (ADS)

    Gruzdev, I. V.; Zenkevich, I. G.; Kondratenok, B. M.

    2015-06-01

    Substituted anilines and phenols are the most common hydrophilic organic environmental toxicants. The principles of gas chromatographic determination of trace amounts of these compounds in aqueous media at concentrations <=0.1 μg litre-1 based on synthesis of their derivatives (derivatization) directly in the aqueous phase are considered. Conversion of relatively hydrophilic analytes into more hydrophobic derivatives makes it possible to achieve such low detection limits and optimize the protocols of extractive preconcentration and selective chromatographic detection. Among the known reactions, this condition is best met by electrophilic halogenation of compounds at the aromatic moiety. The bibliography includes 177 references.

  1. Performance of the MOMA Gas Chromatograph-Mass Spectrometer onboard the 2018 ExoMars Mission

    NASA Astrophysics Data System (ADS)

    Buch, Arnaud; Pinnick, Veronica; Szopa, Cyril; Grand, Noël; Freissinet, Caroline; Danell, Ryan; van Ameron, Friso; Arevalo, Ricardo; Brinckerhoff, William; Raulin, François; Mahaffy, Paul; Goesmann, Fred

    2015-04-01

    The Mars Organic Molecule Analyzer (MOMA) is a dual ion source linear ion trap mass spectrometer that was designed for the 2018 joint ESA-Roscosmos mission to Mars. The main scientific aim of the mission is to search for signs of extant or extinct life in the near subsurface of Mars by acquir-ing samples from as deep as 2 m below the surface. MOMA will be a key analytical tool in providing chemical (molecular) information from the solid samples, with particular focus on the characterization of organic content. The MOMA instrument, itself, is a joint venture for NASA and ESA to develop a mass spectrometer capable of analyzing samples from pyrolysis gas chromatograph (GC) as well as ambient pressure laser desorption ionization (LDI). The combination of the two analytical techniques allows for the chemical characterization of a broad range of compounds, including volatile and non-volatile species. Generally, MOMA can provide in-formation on elemental and molecular makeup, po-larity, chirality and isotopic patterns of analyte spe-cies. Here we report on the current performance of the MOMA prototype instruments, specifically the demonstration of the gas chromatography-mass spec-trometry (GC-MS) mode of operation. Both instruments have been tested separately first and have been coupled in order to test the efficiency of the future MOMA GC-MS instrument. The main objective of the second step has been to test the quantitative response of both instruments while they are coupled and to characterize the combined instrument detection limit for several compounds. A final experiment has been done in order to test the feasibility of the separation and detection of a mixture contained in a soil sample introduced in the MOMA oven.

  2. Development of and fabrication of high resolution gas chromatographic capillary columns

    NASA Technical Reports Server (NTRS)

    Zlatkis, A.

    1982-01-01

    Gas chromatographic columns which are used in the trace gas analyzer (TGA) for the space shuttle are coated with a polyoxyethylene lauryl ether. This stationary phase is of medium polarity and has a temperature limit of 160 C. A polymer for this application which has an improved thermal stability is investigated. The use of fused silica capillary columns with specially bonded phases as well as an introduction system (on column) was also studied.

  3. Anisotropic membranes for gas separation

    DOEpatents

    Gollan, A.Z.

    1987-07-21

    A gas separation membrane has a dense separating layer about 10,000 Angstroms or less thick and a porous support layer 10 to 400 microns thick that is an integral unit with gradually and continuously decreasing pore size from the base of the support layer to the surface of the thin separating layer and is made from a casting solution comprising ethyl cellulose and ethyl cellulose-based blends, typically greater than 47.5 ethoxyl content ethyl cellulose blended with compatible second polymers, such as nitrocellulose. The polymer content of the casting solution is from about 10% to about 35% by weight of the total solution with up to about 50% of this polymer weight a compatible second polymer to the ethyl cellulose in a volatile solvent such as isopropanol, methylacetate, methanol, ethanol, and acetone. Typical nonsolvents for the casting solutions include water and formamide. The casting solution is cast in air from about zero to 10 seconds to allow the volatile solvent to evaporate and then quenched in a coagulation bath, typically water, at a temperature of 7--25 C and then air dried at ambient temperature, typically 10--30 C. 2 figs.

  4. Anisotropic membranes for gas separation

    DOEpatents

    Gollan, Arye Z.

    1987-01-01

    A gas separation membrane has a dense separating layer about 10,000 Angstroms or less thick and a porous support layer 10 to 400 microns thick that is an integral unit with gradually and continuously decreasing pore size from the base of the support layer to the surface of the thin separating layer and is made from a casting solution comprising ethyl cellulose and ethyl cellulose-based blends, typically greater than 47.5 ethoxyl content ethyl cellulose blended with compatible second polymers, such as nitrocellulose. The polymer content of the casting solution is from about 10% to about 35% by weight of the total solution with up to about 50% of this polymer weight a compatible second polymer to the ethyl cellulose in a volatile solvent such as isopropanol, methylacetate, methanol, ethanol, and acetone. Typical nonsolvents for the casting solutions include water and formamide. The casting solution is cast in air from about zero to 10 seconds to allow the volatile solvent to evaporate and then quenched in a coagulation bath, typically water, at a temperature of 7.degree.-25.degree. C. and then air dried at ambient temperature, typically 10.degree.-30.degree. C.

  5. A novel and effective chromatographic approach to the separation of isoflavone derivatives from Pueraria lobata.

    PubMed

    Fu, Jiang; Jing, Wenguang; Wang, Weihao; Chen, Sha; Zhang, Jun; Liu, An

    2015-01-01

    A novel and effective chromatographic approach to the separation and purification of isoflavone compounds from Pueraria lobata is described. The method is based on flash chromatography (FC), coupled to preparative high performance liquid chromatography (prep-HPLC) via a six-way valve. The FC step comprised tandem reversed phase columns, pre-packed with MCI gel (Mitsubishi Chemical Corp., Tokyo, Japan) and C18 (Fuji Silysia Chemical Ltd, Osaka, Japan) resin, respectively, and was designed to separate a crude Pueraria lobata extract into several preliminary fractions. Fractions containing the target compounds were then directly injected via the six-way valve into prep-HPLC columns, without further treatment, for final isolation and purification. Nine isoflavonoids were successfully isolated, three through an online mode and the other six through an offline mode. The purities of all compounds exceeded 95.0%, as determined by HPLC with an UV-vis photodiode array detector. The convenience, low solvent consumption, and time-saving advantages of this method offer an attractive and promising approach to the isolation of natural products. PMID:25751785

  6. Micro-machined planar field asymmetric ion mobility spectrometer as a gas chromatographic detector

    NASA Technical Reports Server (NTRS)

    Eiceman, G. A.; Nazarov, E. G.; Miller, R. A.; Krylov, E. V.; Zapata, A. M.

    2002-01-01

    A planar high field asymmetric waveform ion mobility spectrometer (PFAIMS) with a micro-machined drift tube was characterized as a detector for capillary gas chromatography. The performance of the PFAIMS was compared directly to that of a flame ionization detector (FID) for the separation of a ketone mixture from butanone to decanone. Effluent from the column was continuously sampled by the detector and mobility scans could be obtained throughout the chromatographic analysis providing chemical inforrmation in mobility scans orthogonal to retention time. Limits of detection were approximately I ng for measurement of positive ions and were comparable or slightly better than those for the FID. Direct comparison of calibration curves for the FAIMS and the FID was possible over four orders of magnitude with a semi-log plot. The concentration dependence of the PFAIMS mobility scans showed the dependence between ion intensity and ion clustering, evident in other mobility spectrometers and atmospheric pressure ionization technologies. Ions were identified using mass spectrometry as the protonated monomer and the proton bound dimer of the ketones. Residence time for column effluent in the PFAIMS was calculated as approximately 1 ms and a 36% increase in extra-column broadening versus the FID occurred with the PFAIMS.

  7. Headspace gas chromatographic determination of methylene chloride in decaffeinated tea and coffee, with electrolytic conductivity detection.

    PubMed

    Page, B D; Charbonneau, C F

    1984-01-01

    A headspace gas chromatographic procedure is described for the determination of methylene chloride (MC) in decaffeinated tea and coffee. The tea or coffee sample, with added methylene bromide (MB) internal standard, is equilibrated for 1.5 h at 100 degrees C in aqueous sodium sulfate before manual headspace sampling. MC and MB are separated on a Porasil A column at 160 degrees C and detected by using a Coulson electrolytic conductivity detector. For coffee and tea samples spiked at 1.3 ppm MC, as well as commercially decaffeinated teas and coffees containing up to 8 ppm MC, coefficients of variation were 10% or less. For decaffeinated teas, problems involving sample homogeneity and loss of MC before sealing the headspace vial had to be overcome. Similar problems with decaffeinated instant and ground coffees were minimal. The headspace procedure was superior to a previously reported distillation technique. MC was readily detected at 0.05 ppm. Fourteen decaffeinated teas and 15 decaffeinated coffees were analyzed; MC was detected at levels that ranged up to 15.9 and 4.0 ppm, respectively. PMID:6469909

  8. Passive gas separator and accumulator device

    DOEpatents

    Choe, H.; Fallas, T.T.

    1994-08-02

    A separation device employing a gas separation filter and swirler vanes for separating gas from a gas-liquid mixture is provided. The cylindrical filter utilizes the principle that surface tension in the pores of the filter prevents gas bubbles from passing through. As a result, the gas collects in the interior region of the filter and coalesces to form larger bubbles in the center of the device. The device is particularly suited for use in microgravity conditions since the swirlers induce a centrifugal force which causes liquid to move from the inner region of the filter, pass the pores, and flow through the outlet of the device while the entrained gas is trapped by the filter. The device includes a cylindrical gas storage screen which is enclosed by the cylindrical gas separation filter. The screen has pores that are larger than those of the filters. The screen prevents larger bubbles that have been formed from reaching and interfering with the pores of the gas separation filter. The device is initially filled with a gas other than that which is to be separated. This technique results in separation of the gas even before gas bubbles are present in the mixture. Initially filling the device with the dissimilar gas and preventing the gas from escaping before operation can be accomplished by sealing the dissimilar gas in the inner region of the separation device with a ruptured disc which can be ruptured when the device is activated for use. 3 figs.

  9. Indirect gas chromatographic measurement of water for process streams

    SciTech Connect

    Barbour, F.A.

    1993-05-01

    This project was conducted to develop a moisture measurement method for process gas streams of fossil fuels. Objective was to from pyrolysis to measure the molar concentration of water in a gas stream without flow measurements. The method developed has been incorporated into the hydrocarbon gas analysis method currently used at Western Research Institute. A literature search of types of direct measuring moisture sensors was conducted, and a list of sensors available is given; most of them could not survive in the environment of the process streams. Indirect methods of measuring water involve changing the water via reaction to a compound that can be more readily measured. These methods react water with various reagents to form hydrogen, acetylene, and acetone. The method chose for this study uses a calcium carbide reaction column to convert the water present in the gas stream to acetylene for analysis. Relative deviation for the daily determination of water varied from 0.5 to 3.4%. The method chosen was tested for linearity over a wide range of gas stream water content. Response over 2 to 15 mole % water appears to be linear with a correlation coefficient of 0.991.

  10. Development of gas chromatographic system for dissolved organic carbon analysis in seawater. Annual progress report

    SciTech Connect

    Chipman, D.W.; Takahashi, T.

    1992-12-01

    During the first six months of this two-year grant, we have completed the construction of the analytical portion of a prototype gas chromatograph-based system for the analysis of dissolved organic carbon in seawater. We also have begun testing the procedures to be used to cryogenically concentrate and transfer carbon dioxide from the oxidizing atmosphere of the high-temperature furnace into the reducing hydrogen carrier gas of the gas chromatograph. During the second half of the first year, we will construct the high-temperature catalytic oxidation furnace and test the entire system on laboratory-prepared aqueous solutions of various organic compounds. Also during this period, we will take part in an initial scoping study within the Cape Hatteras field area on board the R/V Gyre. This study will involve both the collection of samples of seawater for organic and inorganic carbon analysis and the measurement of surface-water pCO{sub 2}.

  11. Development of gas chromatographic system for dissolved organic carbon analysis in seawater

    SciTech Connect

    Chipman, D.W.; Takahashi, T.

    1992-12-01

    During the first six months of this two-year grant, we have completed the construction of the analytical portion of a prototype gas chromatograph-based system for the analysis of dissolved organic carbon in seawater. We also have begun testing the procedures to be used to cryogenically concentrate and transfer carbon dioxide from the oxidizing atmosphere of the high-temperature furnace into the reducing hydrogen carrier gas of the gas chromatograph. During the second half of the first year, we will construct the high-temperature catalytic oxidation furnace and test the entire system on laboratory-prepared aqueous solutions of various organic compounds. Also during this period, we will take part in an initial scoping study within the Cape Hatteras field area on board the R/V Gyre. This study will involve both the collection of samples of seawater for organic and inorganic carbon analysis and the measurement of surface-water pCO[sub 2].

  12. Chromatographic fractionation of fullerenes containing noble gas atoms

    NASA Astrophysics Data System (ADS)

    Saunders, M.; Khong, A.; Shimshi, R.; Jiménez-Vázquez, H. A.; Cross, R. J.

    1996-01-01

    Buckminsterfullerence containing krypton atoms inside the cage was partially separated from empty fullerene via column chromatography. The krypton content of portions of the peak emerging from the column was determined by the pyrolytic release of the krypton followed by mass spectrometry. It was found that material emerging more slowly is about 30% enriched over a faster fraction.

  13. Passive gas separator and accumulator device

    DOEpatents

    Choe, Hwang; Fallas, Thomas T.

    1994-01-01

    A separation device employing a gas separation filter and swirler vanes for separating gas from a gasliquid mixture is provided. The cylindrical filter utilizes the principle that surface tension in the pores of the filter prevents gas bubbles from passing through. As a result, the gas collects in the interior region of the filter and coalesces to form larger bubbles in the center of the device. The device is particularly suited for use in microgravity conditions since the swirlers induce a centrifugal force which causes liquid to move from the inner region of the filter, pass the pores, and flow through the outlet of the device while the entrained gas is trapped by the filter. The device includes a cylindrical gas storage screen which is enclosed by the cylindrical gas separation filter. The screen has pores that are larger than those of the filters. The screen prevents larger bubbles that have been formed from reaching and interfering with the pores of the gas separation filter. The device is initially filled with a gas other than that which is to be separated. This technique results in separation of the gas even before gas bubbles are present in the mixture. Initially filling the device with the dissimilar gas and preventing the gas from escaping before operation can be accomplished by sealing the dissimilar gas in the inner region of the separation device with a ruptured disc which can be ruptured when the device is activated for use.

  14. The Construction of a Simple Pyrolysis Gas Chromatograph.

    ERIC Educational Resources Information Center

    Hedrick, Jack L.

    1982-01-01

    Describes a simple and inexpensive pyrolysis gas chromatography (PGC) system constructed from items available in undergraduate institutions. The system is limited, accepting only liquid samples and pyrolyzing "on the fly" rather than statically and not allowing for reductive pyrolysis. Applications, experiments, and typical results are included.…

  15. Computer assisted optimization of liquid chromatographic separations of small molecules using mixed-mode stationary phases.

    PubMed

    Ordoñez, Edgar Y; Benito Quintana, José; Rodil, Rosario; Cela, Rafael

    2012-05-18

    Mixed-mode stationary phases are gaining adepts in liquid chromatography (LC) as more and more applications are published and new commercial columns appear in the market ought to their ability to retain and separate analytes with multiple functionalities. The increased number of adjustable variables gives these columns an enhanced value for the chromatographer, but, on the other hand, it complicates the process of developing satisfactory separations when complex samples must be analyzed. Thus, the availability of computer assisted methods development (CAMD) tools is highly desirable in this field. Therefore, the first specific tool for the CAMD of LC separations in mixed-mode columns is presented. The tool consists in two processes. The first one develops a retention model for peaks in a predefined experimental domain of pH and buffer concentration. In this domain, the retention as a function of the proportion of organic modifier is modeled using a two-stage re-calibration process departing from isocratic retention data and then, from gradient elutions. With this two-stage approach, reliability is gained. In the second process, the model is finally interpolated and used for the unattended optimization of the different possible elution modes available in these columns. This optimization process is driven by an evolutionary algorithm. The development and application of this new chemometrics tool is demonstrated by the optimization of a mixture of neutral and ionizable compounds. Hence, several different types of gradients were generated, showing a good agreement between simulated and experimental data, with retention time errors lower than 5% in most cases. On the other hand, classical CAMD tools, such as design of experiments, were unable to efficiently deal with mixed-mode optimizations, rendering errors above 30% for several compounds. PMID:22494641

  16. Ion Exchange and Thin Layer Chromatographic Separation and Identification of Amino Acids in a Mixture: An Experiment for General Chemistry and Biotechnology Laboratories

    ERIC Educational Resources Information Center

    Brunauer, Linda S.; Caslavka, Katelyn E.; Van Groningen, Karinne

    2014-01-01

    A multiday laboratory exercise is described that is suitable for first-year undergraduate chemistry, biochemistry, or biotechnology students. Students gain experience in performing chromatographic separations of biomolecules, in both a column and thin layer chromatography (TLC) format. Students chromatographically separate amino acids (AA) in an…

  17. Factorial-design optimization of gas chromatographic analysis of tetrabrominated to decabrominated diphenyl ethers. Application to domestic dust.

    PubMed

    Regueiro, Jorge; Llompart, Maria; Garcia-Jares, Carmen; Cela, Rafael

    2007-07-01

    Gas chromatographic analysis of polybrominated diphenyl ethers (PBDEs) has been evaluated in an attempt to achieve better control of the separation process, especially for highly substituted congeners. Use of a narrow-bore capillary column enabled adequate determination of tetra, penta, hexa, hepta, octa, nona and decaBDE congeners in only one chromatographic run while maintaining resolution power similar to that of conventional columns. A micro electron-capture detector (GC-microECD) was used. Chromatographic conditions were optimized by multifactorial experimental design, with the objective of obtaining not only high sensitivity but also good precision. In this way two different approaches to maximizing response and minimizing variability were tested, and are fully discussed. These optimum chromatographic conditions were then used to determine PBDEs extracted from domestic dust samples by microwave-assisted solvent extraction (MASE). Quantitative recovery (90-108%) was achieved for all the PBDEs and method precision (RSD < 13%) was satisfactory. Accuracy was tested by use of the standard reference material SRM 2585, and sub-ng g(-1) limits of detection were obtained for all compounds except BDE-209 (1.44 ng g(-1)). Finally, several samples of house dust were analysed by use of the proposed method and all the target PBDEs were detected in all the samples. BDE-209 was the predominant congener. Amounts varied from 58 to 1615 ng g(-1) and the average contribution to the total PBDE burden of 52%. The main congeners of the octaBDE mixture (BDE-183, BDE-197, BDE-207 and BDE-196) also made an important contribution (29%) to the total. These are the first data about the presence of these compounds in European house-dust samples. Finally, the sum of the main congeners in the pentaBDE commercial mixture (BDE-47, BDE-99, and BDE-100) contributed 14% to the total. Figure Polybrominated diphenyl ethers in House Dust. PMID:17541561

  18. An automated multidimensional preparative gas chromatographic system for isolation and enrichment of trace amounts of xenon from ambient air.

    PubMed

    Larson, Tuula; Östman, Conny; Colmsjö, Anders

    2011-04-01

    The monitoring of radioactive xenon isotopes is one of the principal methods for the detection of nuclear explosions in order to identify clandestine nuclear testing. In this work, a miniaturized, multiple-oven, six-column, preparative gas chromatograph was constructed in order to isolate trace quantities of radioactive xenon isotopes from ambient air, utilizing nitrogen as the carrier gas. The multidimensional chromatograph comprised preparative stainless steel columns packed with molecular sieves, activated carbon, and synthetic carbon adsorbents (e.g., Anasorb®-747 and Carbosphere®). A combination of purification techniques--ambient adsorption, thermal desorption, back-flushing, thermal focusing, and heart cutting--was selectively optimized to produce a well-defined xenon peak that facilitated reproducible heart cutting and accurate quantification. The chromatographic purification of a sample requires approximately 4 h and provides complete separation of xenon from potentially interfering components (such as water vapor, methane, carbon dioxide, and radon) with recovery and accuracy close to 100%. The preparative enrichment process isolates and concentrates a highly purified xenon gas fraction that is suitable for subsequent ultra-low-level γ-, ß/γ-spectroscopic or high-resolution mass spectrometric measurement (e.g., to monitor the gaseous fission products of nuclear explosions at remote locations). The Xenon Processing Unit is a free-standing, relatively lightweight, and transportable system that can be interfaced to a variety of sampling and detection systems. It has a relatively inexpensive, rugged, and compact modular (19-inch rack) design that provides easy access to all parts for maintenance and has a low power requirement. PMID:21347675

  19. Gas chromatographic determination of clopidol in chicken tissues.

    PubMed

    Ekström, L G; Kuivinen, J

    1984-01-01

    A method has been developed for the determination of clopidol residues in chicken tissues. After extraction and cleanup, clopidol is esterified in a 2-phase system to clopidol propionate, which is determined by gas chromatography. The 2-phase system includes, in addition to the clopidol dissolved in methanol, aqueous borax solution, hexane, propionic anhydride, and pyridine. Use of these reagents precludes the use of explosive or carcinogenic chemicals in the derivatization step, and the method is therefore suitable for routine laboratory analysis. Levels of 0.5 ppb clopidol in tissue can be determined. PMID:6501161

  20. Gas chromatographic determination of nitrogen oxide and dioxide using a photoionization detector

    SciTech Connect

    Bulycheva, Z.Yu.; Panina, L.I.; Rudenko, B.A.

    1995-01-01

    Recently, fundamentally new possibilities of detecting NO and NO{sub 2} have been connected with the use of a photoionization detector (PID), which is based on the ionization of analyzed components under vacuum UV radiation. The extensive experimental material on the employment of PID in the gas chromatographic analysis of different samples of organic and inorganic origin is given earlier. However there is no information about the practical use of PIDs for the analysis of NO and NO{sub 2}. The results obtained by using a PID for the gas-chromatographic analysis of a mixture of NO and NO{sub 2} are presented in this work. A specific Kuprumsorb sorbent based on a macroporous sulfonated cation-exchange resin in the Cu{sup 2+} form was used.

  1. Recirculating gas separator for electric submersible

    SciTech Connect

    Powers, M.L.

    1991-01-01

    This patent describes a gas separator apparatus for a submersible well pump. It comprises: a rotary gas separator means; and recirculating means for recirculating a portion of the liquid discharged from the discharge outlet back to the separating chamber so that a gas-to-liquid ratio in the separator means is substantially lower than a gas-to-liquid ratio of well fluid entering the well fluid inlet wherein the recirculating means. This patent also describes a method of pumping liquid from a well producing well fluids having a relatively high gas-to-liquid ratio. It comprises: centrifugally separating the well fluid into a liquid and a gas with a separator located downhole in the well; directing the separated liquid toward an inlet of a submersible well pump; recycling a portion of the separated liquid to the separator; and providing an effective gas-to-liquid ratio in the separator substantially lower than a gas-to-liquid ratio of the well fluid prior to separation.

  2. Inverse gas chromatography and other chromatographic techniques in the examination of engine oils.

    PubMed

    Fall, Jacek; Voelkel, Adam

    2002-09-01

    The emerging market of engine oils consists of a number of products from different viscosity and quality classes. Determination of the base oil used in manufacturing of the final product (engine oil) as well as estimation of mutual miscibility of oils and their solubility could be crucial problems. Inverse gas chromatography and other chromatographic techniques are presented as an interesting and fruitful extension of normalised standard analytical methods used in the oil industry. PMID:12385390

  3. Portable gas chromatograph mass spectrometer for on-site chemical analyses

    DOEpatents

    Haas, Jeffrey S.; Bushman, John F.; Howard, Douglas E.; Wong, James L.; Eckels, Joel D.

    2002-01-01

    A portable, lightweight (approximately 25 kg) gas chromatograph mass spectrometer, including the entire vacuum system, can perform qualitative and quantitative analyses of all sample types in the field. The GC/MS has a conveniently configured layout of components for ease of serviceability and maintenance. The GC/MS system can be transported under operating or near-operating conditions (i.e., under vacuum and at elevated temperature) to reduce the downtime before samples can be analyzed on-site.

  4. Gas chromatographic identification of Clostridium difficile and detection of cytotoxin from a modified selective medium.

    PubMed Central

    Levett, P N; Phillips, K D

    1985-01-01

    A modification of an existing selective medium for Clostridium difficile is described. Inclusion in the medium of DL nor-leucine and p-hydroxyphenylacetic acid enables identification of C difficile to be made directly from primary isolation plates by gas chromatographic detection of caproic acid and p-cresol. Plugs of agar withdrawn from the selective medium also allow the detection of cytotoxin production in vitro. PMID:3968212

  5. Mechanism and kinetics of protein transport in chromatographic media studied by confocal laser scanning microscopy. Part II. Impact on chromatographic separations.

    PubMed

    Hubbuch, Jürgen; Linden, Thomas; Knieps, Esther; Thömmes, Jörg; Kula, Maria-Regina

    2003-12-22

    The impact of different transport mechanism on chromatographic performance was studied by confocal laser scanning microscopy (CLSM) for solutions containing bovine serum albumin (BSA) and monoclonal IgG 2a under different solid- and fluid-phase conditions. During this investigation, a clear influence of the uptake mechanism on the affinity of the respective proteins for the different adsorbents and thus separation performance of the chromatographic process could be observed. For the system SP Sepharose Fast Flow at pH 4.5 pore diffusion could be ascribed to be the dominant transport mechanism for both proteins and the adsorption profiles resembled a pattern similar to that described by the 'shrinking core' model. Under these conditions a significantly higher affinity towards the adsorbent was found for BSA when compared to IgG 2a. With changing fluid- and solid-phase conditions, however, a change of the transport mode for IgG 2a could be detected. While the exact mechanism is still unresolved it could be concluded that both occurrence and magnitude of the now governing transport mechanism depended on protein properties and interaction with the adsorbent surface. For the system SP Sepharose XL at pH 5.0 both parameters leading to the change in IgG 2a uptake were combined resulting in a clear change of the system affinity towards the IgG 2a molecule, while BSA adsorption was restricted to the most outer shell of the sorbent. PMID:14735979

  6. Gas chromatographic determination of residual solvents in lubricating oils and waxes

    SciTech Connect

    De Andrade Bruening, I.M.R.

    1983-10-01

    A direct gas-liquid chromatographic analysis of residual solvents is described, using tert-butylbenzene as an internal standard. The lube oils and waxes were prevented from contaminating the chromatographic column by injecting the samples directly into a precolumn containing a silicone stationary phase. The samples of lube oils and waxes were injected directly into the chromatographic column containing another stationary phase, 1,2,3-tris(2-cyanoethoxy)propane. (The waxy samples were dissolved in a light neutral oil). With proper operating conditions, analysis time was 7 min. The procedure has been applied in the control of a lube oil dewaxing plant; the chromatographic column showed no sign of deterioration after 1 h when the precolumn was removed. Known amounts of toluene and methylethyl ketone were added to the solvent-free lubricating oils and wax, and these mixtures were analyzed to evaluate the accuracy of the procedure. Precision and accuracy of these data are comparable to those of methods previously described. 1 figure, 1 table.

  7. Gas chromatographic determination of triclopyr in fruits and vegetables.

    PubMed

    Ting, K C; Lee, C S

    1995-01-20

    This research was comprised of two parts: quantitative analyses, and confirmatory test. In the quantitative analyses, five classes of fruits and vegetables comprising 10 individual commodities were fortified with triclopyr herbicide at 0.4 and 0.8 ppm level. Triclopyr was extracted from the matrices and derivatized separately to 2-chloroethylene ester with 2-chloroethanol-BCl3 and methyl ester with diazomethane. The esters were then quantitated by GC-ECD and GC-NPD. The GC-ECD recoveries for 2-chloroethylene ester were 100.0% and 100.7% at 0.4 ppm and 0.8 ppm fortification levels, respectively, whereas methyl ester recovery was 103.9% at 0.4 ppm fortification level. Similarly, the GC-NPD recoveries for 2-chloroethylene ester were 99.0% and 97.9% at 0.4 ppm and 0.8 ppm fortification levels respectively, whereas methyl ester recovery was 102.0% at 0.4 ppm fortification level. In the confirmatory test, the 2-chloroethylene ester was introduced into a GC-ion trap. The EI mass spectrum was then interpreted based on the criteria of molecular ion, isotopes, base ion, characteristic ions and the nitrogen rule. Compared to existing methods, this method has reduced partition solvents to nearly one-tenth. In addition, this method proved to be simple, fast, safe and accurate. PMID:7881537

  8. Liquid/Gas Separator Handles Varying Loads

    NASA Technical Reports Server (NTRS)

    Mann, John

    1992-01-01

    Liquid/gas separator includes two independent motors, one for pumping mixture and other for drawing off extracted gas. Two materials moved at speeds best suited for them. Liquid expelled radially outward from separator rotor. Entrained gas released, flows axially through rotor, and leaves through fan at downstream end. Unit developed to separate air from urine in spacecraft wastewater-treatment system, also functions in normal gravity. Made largely of titanium to resist corrosion.

  9. Determination of calcium stearate in polyolefin samples by gas chromatographic technique after performing dispersive liquid-liquid microextraction.

    PubMed

    Ranji, Ali; Ghorbani Ravandi, Mahboobeh; Farajzadeh, Mir Ali

    2008-05-01

    In this study, a gas chromatographic method is presented for the determination of calcium stearate after its conversion to stearic acid in a polymeric matrix. A solution of hydrochloric acid in 2-propanol is used as an extracting solvent of calcium stearate and its converter to stearic acid. For stearic acid preconcentration before its injection to a separation system, a recently presented extraction method, dispersive liquid-liquid microextraction, using carbon tetrachloride as an extracting solvent is used. Finally, 1 microL of the organic phase collected at the bottom of a conical test tube after centrifuging is injected into a gas chromatograph (GC) for quantification. This method has a relatively broad linear dynamic range (50 - 2000 mg/L) with a limit of detection (LOD) of 15 mg/L for stearic acid in solution. The LOD of the proposed method in a polymeric sample using 10 mg of polymer is 60 ppm as calcium stearate. Some effective parameters, such as the time and temperature of heating, the concentration of hydrochloric acid and the volume of distilled water, were studied. PMID:18469468

  10. Comparison of gas chromatographic hyphenated techniques for mercury speciation analysis.

    PubMed

    Nevado, J J Berzas; Martín-Doimeadios, R C Rodríguez; Krupp, E M; Bernardo, F J Guzmán; Fariñas, N Rodríguez; Moreno, M Jiménez; Wallace, D; Ropero, M J Patiño

    2011-07-15

    In this study, we evaluate advantages and disadvantages of three hyphenated techniques for mercury speciation analysis in different sample matrices using gas chromatography (GC) with mass spectrometry (GC-MS), inductively coupled plasma mass spectrometry (GC-ICP-MS) and pyrolysis atomic fluorescence (GC-pyro-AFS) detection. Aqueous ethylation with NaBEt(4) was required in all cases. All systems were validated with respect to precision, with repeatability and reproducibility <5% RSD, confirmed by the Snedecor F-test. All methods proved to be robust according to a Plackett-Burnham design for 7 factors and 15 experiments, and calculations were carried out using the procedures described by Youden and Steiner. In order to evaluate accuracy, certified reference materials (DORM-2 and DOLT-3) were analyzed after closed-vessel microwave extraction with tetramethylammonium hydroxide (TMAH). No statistically significant differences were found to the certified values (p=0.05). The suitability for water samples analysis with different organic matter and chloride contents was evaluated by recovery experiments in synthetic spiked waters. Absolute detection and quantification limits were in the range of 2-6 pg for GC-pyro-AFS, 1-4 pg for GC-MS, with 0.05-0.21 pg for GC-ICP-MS showing the best limits of detection for the three systems employed. However, all systems are sufficiently sensitive for mercury speciation in environmental samples, with GC-MS and GC-ICP-MS offering isotope analysis capabilities for the use of species-specific isotope dilution analysis, and GC-pyro-AFS being the most cost effective alternative. PMID:21641604

  11. AUTOMATED CALIBRATION AND ANALYSIS OF VOCS WITH A CAPILLARY COLUMN GAS CHROMATOGRAPH EQUIPPED FOR REDUCED TEMPERATURE TRAPPING

    EPA Science Inventory

    Recently an automated system for monitoring volatile organics by reduced temperature (-150C) preconcentration and capillary column/gas chromatographic analysis has been assembled and evaluated. The automation has now been extended to include multipoint calibration using single st...

  12. Separation studies of As(III), Sb(III) and Bi(III) by reversed-phase paper chromatographic technique

    SciTech Connect

    Raman, B.; Shinde, V.M.

    1987-07-01

    Reversed-phase paper chromatographic separations of As(III), Sb(III) and Bi(III) have been carried out on Whatman No 1 filter paper impregnated with triphenylphosphine oxide as stationary phase and using organic complexing agents such as sodium acetate, sodium succinate and sodium malonate solutions as active mobile phases. Results for the separation of binary and ternary mixtures are reported and the method has been successfully applied to the separation and detection of these elements present in real samples and at ppm level concentration.

  13. Development of High Precision Metal Micro-Electro-Mechanical-Systems Column for Portable Surface Acoustic Wave Gas Chromatograph

    NASA Astrophysics Data System (ADS)

    Iwaya, Takamitsu; Akao, Shingo; Sakamoto, Toshihiro; Tsuji, Toshihiro; Nakaso, Noritaka; Yamanaka, Kazushi

    2012-07-01

    In the field of environmental measurement and security, a portable gas chromatograph (GC) is required for the on-site analysis of multiple hazardous gases. Although the gas separation column has been downsized using micro-electro-mechanical-systems (MEMS) technology, an MEMS column made of silicon and glass still does not have sufficient robustness and a sufficiently low fabrication cost for a portable GC. In this study, we fabricated a robust and inexpensive high-precision metal MEMS column by combining diffusion-bonded etched stainless-steel plates with alignment evaluation using acoustic microscopy. The separation performance was evaluated using a desktop GC with a flame ionization detector and we achieved the high separation performance comparable to the best silicon MEMS column fabricated using a dynamic coating method. As an application, we fabricated a palm-size surface acoustic wave (SAW) GC combining this column with a ball SAW sensor and succeeded in separating and detecting a mixture of volatile organic compounds.

  14. HPLC method development for the online-coupling of chromatographic Perilla frutescens extract separation with xanthine oxidase enzymatic assay.

    PubMed

    Kaufmann, Christine M; Grassmann, Johanna; Letzel, Thomas

    2016-05-30

    Enzyme-regulatory effects of compounds contained in complex mixtures can be unveiled by coupling a continuous-flow enzyme assay to a chromatographic separation. A temperature-elevated separation was developed and the performance was tested using Perilla frutescens plant extracts of various polarity (water, methanol, ethanol/water). Owning to the need of maintaining sufficient enzymatic activity, only low organic solvent concentrations can be added to the mobile phase. Hence, to broaden the spectrum of eluting compounds, two different organic solvents and various contents were tested. The chromatographic performance and elution was further improved by the application of a moderate temperature gradient to the column. By taking the effect of eluent composition as well as calculated logD values and molecular structure of known extract compounds into account, unknown features were tentatively assigned. The method used allowed the successful observation of an enzymatic inhibition caused by P. frutescens extract. PMID:26986639

  15. Passive gas separator and accumulator device

    SciTech Connect

    Choe, Hwang; Fallas, T.T.

    1993-11-29

    A separation device employing a gas separation filter and swirler vanes for separating gas from a gas-liquid mixture is provided. The cylindrical filter uses the principle that surface tension in the filter pores prevents gas bubbles from passing through; the gas collects in the interior of the filter to form larger bubbles in the center of the device. The device is suited for microgravity since the swirlers induce a centrifugal force which forces liquid from the inner region through the pores and the device outlet while the entrained gas is trapped by the filter. The device includes a cylindrical gas storage screen enclosed by the filter. The screen has pores larger than those of the filters. The screen prevents larger bubbles that have been formed from reaching and interfering with the pores of the filter. The device is initially filled with a gas other than that which is to be separated; this results in separation of the gas even before gas bubbles are present in the mixture. Initially filling the device with the dissimilar gas and preventing the gas from escaping before operation can be accomplished by sealing the dissimilar gas in the inner region with a ruptured disc which can be ruptured when the device is activated for use.

  16. Toward a microfabricated preconcentrator-focuser for a wearable micro-scale gas chromatograph.

    PubMed

    Bryant-Genevier, Jonathan; Zellers, Edward T

    2015-11-27

    This article describes work leading to a microfabricated preconcentrator-focuser (μPCF) designed for integration into a wearable microfabricated gas chromatograph (μGC) for monitoring workplace exposures to volatile organic compounds (VOCs) ranging in vapor pressure from ∼0.03 to 13kPa at concentrations near their respective Threshold Limit Values. Testing was performed on both single- and dual-cavity, etched-Si μPCF devices with Pyrex caps and integrated resistive heaters, packed with the graphitized carbons Carbopack X (C-X) and/or Carbopack B (C-B). Performance was assessed by measuring the 10% breakthrough volumes and injection bandwidths of a series of VOCs, individually and in mixtures, as a function of the VOC air concentrations, mixture complexity, sampling and desorption flow rates, adsorbent masses, temperature, and the injection split ratio. A dual-cavity device containing 1.4mg of C-X and 2.0mg of C-B was capable of selectively and quantitatively capturing a mixture of 14 VOCs at low-ppm concentrations in a few minutes from sample volumes sufficiently large to permit detection at relevant concentrations for workplace applications with the μGC detector that we ultimately plan to use. Thermal desorption at 225°C for 40s yielded ≥99% desorption of all analytes, and injected bandwidths as narrow as 0.6s facilitated efficient separation on a downstream 6-m GC column in <3min. A preconcentration factor of 620 was achieved for benzene from a sample of just 31mL. Increasing the mass of C-X to 2.3mg would be required for exhaustive capture of the more volatile target VOCs at high-ppm concentrations. PMID:26530144

  17. A Gas Chromatograph/Mass Spectrometer System for UltraLow-Emission Combustor Exhaust Studies

    NASA Technical Reports Server (NTRS)

    Brabbs, Theodore A.; Wey, Chowen Chou

    1996-01-01

    A gas chromatograph (GC)/mass spectrometer (MS) system that allows the speciation of unburnt hydrocarbons in the combustor exhaust has been developed at the NASA Lewis Research Center. Combustion gas samples are withdrawn through a water-cooled sampling probe which, when not in use, is protected from contamination by a high-pressure nitrogen purge. The sample line and its connecting lines, filters, and valves are all ultraclean and are heated to avoid condensation. The system has resolution to the parts-per-billion (ppb) level.

  18. A theoretical model for the separation of glucose and fructose mixtures by using a semicontinuous chromatographic refiner

    SciTech Connect

    Lee, Kwang Nam; Lee, Won Kook )

    1992-03-01

    The separation of a glucose and fructose mixture was experimentally performed by using a semicontinuous chromatographic refiner (SCCR) packed with Ca{sup 2+} ion in the form of DOWEX 50W 12X resin. The plug flow model with velocity-dependent mass transfer resistance was resistance was presented for calculating both products and on-concentrations in the SCCR unit, and the validity of the model was experimentally confirmed.

  19. Centrifuge for separating helium from natural gas

    SciTech Connect

    Theyse, F.H.; Kelling, F.E.T.

    1980-01-08

    Ultra Centrifuge Nederland N.V.'s improved centrifuge for separating helium from natural gas comprises a hollow cylindrical rotor, designated as a separating drum, within a stationary housing. Natural gas liquids that condense under pressure in the separating drum pass through openings in the drum into the space between the drum and housing. In this space, a series of openings, or throttling restrictors, allows the liquids to expand and return to gas. The gaseous component that does not liquefy in the drum remains separate for drawing off.

  20. Mars Atmospheric Capture and Gas Separation

    NASA Technical Reports Server (NTRS)

    Muscatello, Anthony; Santiago-Maldonado, Edgardo; Gibson, Tracy; Devor, Robert; Captain, James

    2011-01-01

    The Mars atmospheric capture and gas separation project is selecting, developing, and demonstrating techniques to capture and purify Martian atmospheric gases for their utilization for the production of hydrocarbons, oxygen, and water in ISRU systems. Trace gases will be required to be separated from Martian atmospheric gases to provide pure C02 to processing elements. In addition, other Martian gases, such as nitrogen and argon, occur in concentrations high enough to be useful as buffer gas and should be captured as welL To achieve these goals, highly efficient gas separation processes will be required. These gas separation techniques are also required across various areas within the ISRU project to support various consumable production processes. The development of innovative gas separation techniques will evaluate the current state-of-the-art for the gas separation required, with the objective to demonstrate and develop light-weight, low-power methods for gas separation. Gas separation requirements include, but are not limited to the selective separation of: (1) methane and water from un-reacted carbon oxides (C02- CO) and hydrogen typical of a Sabatier-type process, (2) carbon oxides and water from unreacted hydrogen from a Reverse Water-Gas Shift process, (3) carbon oxides from oxygen from a trash/waste processing reaction, and (4) helium from hydrogen or oxygen from a propellant scavenging process. Potential technologies for the separations include freezers, selective membranes, selective solvents, polymeric sorbents, zeolites, and new technologies. This paper and presentation will summarize the results of an extensive literature review and laboratory evaluations of candidate technologies for the capture and separation of C02 and other relevant gases.

  1. First Results From the Gas Chromatograph Mass Spectrometer (GCMS) Experiment on the Cassini-Huygens Probe

    NASA Technical Reports Server (NTRS)

    Niemann, Hasso B.; Demick, J.; Haberman, J.; Harpold, D.; Kasprzak, W.; Raaen, E.; Way, S.; Atreya, S.; Carignan, G.; Bauer, S.

    2005-01-01

    The Huygens Probe of the Cassini Huygens Mission entered the atmosphere of the moon Titan on January 14,2005. The GCMS was part of the instrument complement on the Probe to measure in situ the chemical composition of the atmosphere during the probe descent and to support the Aerosol Collector Pyrolyser (ACP) experiment by serving as detector for the pyrolization products. The GCMS employed a quadrupole mass filter with a secondary electron multiplier detection system and a gas sampling system providing continuous direct atmospheric composition measurements and batch sampling through three gas chromatographic (GC) columns. The mass spectrometer employed five electron impact ion sources with available electron energies of either 70 or 25 eV. Three ion sources served as detectors for the GC columns and two were dedicated to direct atmosphere sampling and ACP gas sampling, respectively. The GCMS gas inlet was heated to prevent condensation, and served to evaporate surface constituents after impact.

  2. Application of gas chromatographic method in simultaneous measurements of helium, argon and neon concentration in groundwaters

    NASA Astrophysics Data System (ADS)

    Najman, J.; Bielewski, J.; Sliwka, I.

    2012-04-01

    Helium concentration in groundwater is a fine indicator in water dating in a range from a hundred to tens of thousands of years. Gas chromatography (GC) measurements of helium can be used as an alternative to mass spectrometry (MS) determinations of 4He for groundwater dating [1]. Argon and neon concentrations mainly serve for determining the temperature of recharge and the air excess which is needed to correct measured values of helium concentration [2] . A chromatographic measurement system of helium, argon and neon concentration in groundwater is presented [3]. Water samples are taken from groundwater with a precise procedure without contamination with air in a special stainless steel vessels of volume equal to 2900 cm3. Helium is extracted from water samples using the head-space method. After enrichment by cryotrap method helium is analyzed in the gas chromatograph equipped with the thermal conductivity detector (TCD) with detection limit of about 2.8 ng He. The helium limit of detection of presented method is 1,2·10-8 cm3STP/gH2O [4]. We are currently working on adapting the method of cryogenic enrichment of helium concentration for simultaneous measurements of the concentration of helium, argon and neon using single sample of groundwater. Neon will be measured with the thermal conductivity detector and capillary column filled with molecular sieve 5A. Argon will be analyzed also with the thermal conductivity detector and packed column filled with molecular sieve 5A. This work was supported by grant No. N N525 3488 38 from the polish National Science Centre. [1] A. Zuber, W. Ciężkowski, K. Różański (red.), Tracer methods in hydrogeological studies - a methodological guide. Wroclaw University of Technology Publishing House, Wroclaw, 2007 (in polish). [2] P. Mochalski, Chromatographic method for the determination of Ar, Ne and N2 in water, Ph.D. thesis, Institute of Nuclear Physics Polish Academy of Sciences in Krakow, 2003 (in polish). [3] A. Żurek, P

  3. High performance liquid chromatographic separation of polycyclic aromatic hydrocarbons on microparticulate pyrrolidone and application to the analysis of shale oil

    SciTech Connect

    Mourey, T.H.; Siggia, S.; Uden, P.C.; Crowley, R.J.

    1980-05-01

    A chemically bonded pyrrolidone substrate is used for the high performance liquid chromatographic separation of polycyclic aromatic hydrocarbons. The cyclic amide phase interacts electronically with the polycyclic aromatic hydrocarbons in both the normal and reversed phase modes. Separation is effected according to the number of aromatic rings and the type of ring condensation. Information obtained is very different from that observed on hydrocarbon substrates, and thus these phases can be used in a complementary fashion to give a profile of polycyclic aromatics in shale oil samples. 7 figures, 1 table.

  4. Anomalous temperature dependence of gas chromatographic retention indices of polar compounds on non-polar stationary phases.

    PubMed

    Pavlovskii, Alexander A; Héberger, Károly; Zenkevich, Igor G

    2016-05-01

    Increasing the reliability of both GC and GC-MS identification requires appropriate interlaboratory reproducibility of gas chromatographic retention indices (I). Known temperature dependence, I(T), is the main source of non-reproducibility of these parameters. It can be approximated with a simple linear function I(T). However, since mid-1990s-beginning of 2000s some examples of anomalous temperature dependence, I(T), preferably for polar analytes on non-polar stationary phases were revealed independently by different authors. The effect implies the variations in the sign of the temperature coefficients β=dI/dT for selected compounds and, hence, the appearance of the I-extrema (usually, minima). The current work provides evidence that the character of the anomalous I(Т) dependences (ascending, descending, or with extrema) is strongly influenced by the amounts of analytes injected into the chromatographic column, but these anomalies appeared not to be connected directly with the mass overloading of separation systems. The physicochemical model is proposed to describe the observed anomalies of I(T) dependence. This model is based on three previously known principles of chromatography, namely: The superposition of these objectives allows understanding both the unusual temperature dependence of retention indices, and the influence of the amounts of polar analytes injected into GC column on the parameters of this dependence. PMID:27062719

  5. Balloonborne in situ gas chromatograph for measurements in the troposphere and stratosphere

    NASA Astrophysics Data System (ADS)

    Moore, F. L.; Elkins, J. W.; Ray, E. A.; Dutton, G. S.; Dunn, R. E.; Fahey, D. W.; McLaughlin, R. J.; Thompson, T. L.; Romashkin, P. A.; Hurst, D. F.; Wamsley, P. R.

    2003-03-01

    An in situ gas chromatograph (GC) instrument on a balloonborne package is described in detail and data from seven science deployments are presented. This instrument, the Lightweight Airborne Chromatograph Experiment (LACE), operates on the Observations of the Middle Stratosphere (OMS) in situ gondola and has taken data from the upper troposphere to near 32 km with a vertical resolution of better than 300 m. LACE chromatography has been developed to measure halon-1211, the chlorofluorocarbons (CFC-11, CFC-113, CFC-12), nitrous oxide (N2O), and sulfur hexafluoride (SF6) every 70 s and methyl chloroform (CH3CCl3), carbon tetrachloride (CCl4), hydrogen (H2), methane (CH4), and carbon monoxide (CO) every 140 s. In the introduction we present scientific motivation for choosing this suite of molecules and for the use of faster sample rates resulting in unprecedented vertical resolution from an in situ GC. Results from an intercomparison with the Airborne Chromatograph for Atmospheric Trace Species (ACATS-IV) instrument are shown to quantitatively connect this LACE data set to the complementary data set generated on board the NASA ER-2 aircraft.

  6. Miniature triaxial metastable ionization detector for gas chromatographic trace analysis of extraterrestrial volatiles

    NASA Technical Reports Server (NTRS)

    Woeller, F. H.; Kojiro, D. R.; Carle, G. C.

    1984-01-01

    The present investigation is concerned with a miniature metastable ionization detector featuring an unconventional electrode configuration, whose performance characteristics parallel those of traditional design. The ionization detector is to be incorporated in a flight gas chromatograph (GC) for use in the Space Shuttle. The design of the detector is discussed, taking into account studies which verified the sensitivity of the detector. The triaxial design of the detector is compared with a flat-plate style. The obtained results show that the principal goal of developing a miniature, highly sensitive ionization detector for flight applications was achieved. Improved fabrication techniques will utilize glass-to-metal seals and brazing procedures.

  7. Capillary gas chromatographic determination of dimethachlon residues in fresh tobacco leaves and cut-tobacco*

    PubMed Central

    Liu, Hong-cheng; Li, Qi-wan; Tang, Li-bin

    2007-01-01

    Simple procedures for extraction and chromatographic determination of dimethachlon residues in fresh tobacco leaves and cut-tobacco are described. The determination was carried out by capillary gas chromatography (GC) with electron capture detection (ECD) and confirmed by GC-MS. The mean recoveries and relative standard deviation (RSD) were 93.2%~112.9% and 3.5%~6.7%, respectively at levels ranging from 0.01 to 0.1 mg/kg. The limit of determination was 0.001 mg/kg. Tobacco samples in routine check were successfully analyzed using the proposed method. PMID:17444603

  8. Screening of ground water samples for volatile organic compounds using a portable gas chromatograph

    USGS Publications Warehouse

    Buchmiller, R.C.

    1989-01-01

    A portable gas chromatograph was used to screen 32 ground water samples for volatile organic compounds. Seven screened samples were positive; four of the seven samples had volatile organic substances identified by second-column confirmation. Four of the seven positive, screened samples also tested positive in laboratory analyses of duplicate samples. No volatile organic compounds were detected in laboratory analyses of samples that headspace screening indicated to be negative. Samples that contained volatile organic compounds, as identified by laboratory analysis, and that contained a volatile organic compound present in a standard of selected compounds were correctly identified by using the portable gas chromatography. Comparisons of screened-sample data with laboratory data indicate the ability to detect selected volatile organic compounds at concentrations of about 1 microgram per liter in the headspace of water samples by use of a portable gas chromatography. -Author

  9. Gas chromatographic organic acid profiling analysis of brandies and whiskeys for pattern recognition analysis.

    PubMed

    Park, Y J; Kim, K R; Kim, J H

    1999-06-01

    An efficient gas chromatographic profiling and pattern recognition method is described for brandy and whiskey samples according to their organic acid contents. It involves solid-phase extraction of organic acids using Chromosorb P with subsequent conversion to stable tert-butyldimethylsilyl derivatives for the direct analysis by capillary column gas chromatography and gas chromatography-mass spectrometry. A total of 12 organic acids were reproducibly identified in liquor samples (1 mL). When the GC profiles were simplified to their retention index spectra, characteristic patterns were obtained for each liquor sample as well as for each group average. Stepwise discriminant analysis provided star symbols characteristic for each liquor sample and group average. As expected, canonical discriminant analysis correctly classified 23 liquor samples studied into two groups of either brandy or whiskey. PMID:10794629

  10. Radioactive-gas separation technique

    NASA Technical Reports Server (NTRS)

    Haney, R.; King, K. J.; Nellis, D. O.; Nisson, R. S.; Robling, P.; Womack, W.

    1977-01-01

    Cryogenic technique recovers gases inexpensively. Method uses differences in vapor pressures, melting points, and boiling points of components in gaseous mixture. Series of temperature and pressure variations converts gases independently to solid and liquid states, thereby simplifying separation. Apparatus uses readily available cryogen and does not require expensive refrigeration equipment.

  11. Recent development in chromatographic techniques

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chromatographic techniques play a significant role in the determination of analytes in complex matrices, separating individual sample components prior to their detection. In the analysis of contaminants and chemical residues in foods, gas chromatography (GC) and liquid chromatography (LC) are two m...

  12. Method for improved gas-solids separation

    DOEpatents

    Kusik, Charles L.; He, Bo X.

    1990-01-01

    Methods are disclosed for the removal of particulate solids from a gas stream at high separation efficiency, including the removal of submicron size particles. The apparatus includes a cyclone separator type of device which contains an axially mounted perforated cylindrical hollow rotor. The rotor is rotated at high velocity in the same direction as the flow of an input particle-laden gas stream to thereby cause enhanced separation of particulate matter from the gas stream in the cylindrical annular space between the rotor and the sidewall of the cyclone vessel. Substantially particle-free gas passes through the perforated surface of the spinning rotor and into the hollow rotor, from when it is discharged out of the top of the apparatus. Separated particulates are removed from the bottom of the vessel.

  13. Method for improved gas-solids separation

    DOEpatents

    Kusik, C.L.; He, B.X.

    1990-11-13

    Methods are disclosed for the removal of particulate solids from a gas stream at high separation efficiency, including the removal of submicron size particles. The apparatus includes a cyclone separator type of device which contains an axially mounted perforated cylindrical hollow rotor. The rotor is rotated at high velocity in the same direction as the flow of an input particle-laden gas stream to thereby cause enhanced separation of particulate matter from the gas stream in the cylindrical annular space between the rotor and the sidewall of the cyclone vessel. Substantially particle-free gas passes through the perforated surface of the spinning rotor and into the hollow rotor, from where it is discharged out of the top of the apparatus. Separated particulates are removed from the bottom of the vessel. 4 figs.

  14. Simulation of Ultrasonic-driven Gas Separations

    SciTech Connect

    Rector, David R.; Greenwood, Margaret S.; Ahmed, Salahuddin; Doctor, Steven R.; Posakony, Gerald J.; Stenkamp, Victoria S.

    2007-06-01

    The separation of components in a gas mixture is important for a wide range of applications. One method for achieving this separation is by passing a traveling acoustic wave through the gas mixture, which creates a flux of the lighter components away from the transducer. A series of simulation were performed to assess the effectiveness of this method for separating a binary mixture of argon and helium using the lattice kinetics method. The energy transport equation was modified to account for adiabatic expansion and compression. The species transport equation was modified to include a barodiffusion term. Simulations were performed on two different scales; detailed acoustic wave simulations to determine the net component flux as a function of local concentration, pressure, etc., and device scale simulations to predict the gas composition as a function of time inside a gas separation cylinder. The method is first validated using data from literature and then applied to mixtures of argon and helium. Results are presented and discussed.

  15. Mesoporous Carbon Membranes for Selective Gas Separations

    SciTech Connect

    2009-04-01

    This factsheet describes a study whose focus is on translating a novel class of material developed at Oak Ridge National Laboratory—selfassembled mesoporous carbon—into robust, efficient membrane systems for selective industrial gas separations.

  16. Application of Gas Chromatographic analysis to RPC detectors in the ATLAS experiment at CERN-LHC

    NASA Astrophysics Data System (ADS)

    de Asmundis, R.

    2007-06-01

    Starting from 2007 a large number (1200) Resistive Plate Chambers (RPC) detectors will be used as muon trigger detectors in the ATLAS Experiment at CERN-LHC accelerator. RPC are gaseous detector in which the quality and the stability of the gas mixture as well as the design of the gas supplying system, play a fundamental role in their functioning. RPC are foreseen to work more than ten years in the high radiation environment of ATLAS and the gas mixture acts really as a "lifeguard" for the detectors. For this reason a great attention has been devoted to the gas studies in order to optimize RPC performance, robustness and reliability in a high radiation environment. In this paper we describe the work done to decide how to supply and control in an optimal way the gas to the detectors, in order to ensure their best performance for a long time. The activity, based on Gas Chromatographic (GC) analysis, has been carried on a sample of final RPC working in radiation conditions much more intense than those foreseen for the ATLAS experiment. This has been possible using a high Gamma ray radiation facility available at CERN (GIF). The gas has been supplied using a system similar but at a reduced scale with respect to the final one and including: a recirculation circuit, a humidification module and a three stages purification subsystem.

  17. A gas chromatographic instrument for measurement of hydrogen cyanide in the lower atmosphere

    NASA Astrophysics Data System (ADS)

    Ambrose, J. L.; Zhou, Y.; Haase, K.; Mayne, H. R.; Talbot, R.; Sive, B. C.

    2012-06-01

    A gas-chromatographic (GC) instrument was developed for measuring hydrogen cyanide (HCN) in the lower atmosphere. The main features of the instrument are (1) a cryogen-free cooler for sample dehumidification and enrichment, (2) a porous polymer PLOT column for analyte separation, (3) a flame thermionic detector (FTD) for sensitive and selective detection, and (4) a dynamic dilution system for calibration. We deployed the instrument for a ∼4 month period from January-June, 2010 at the AIRMAP atmospheric monitoring station Thompson Farm 2 (THF2) in rural Durham, NH. A subset of measurements made during 3-31 March is presented here with a detailed description of the instrument features and performance characteristics. The temporal resolution of the measurements was ~20 min, with a 75 s sample capture time. The 1σ measurement precision was <10% and the instrument response linearity was excellent on a calibration scale of 0.10-0.75 ppbv (±5%). The estimated method detection limit (MDL) and accuracy were 0.021 ppbv and 15%, respectively. From 3-31 March 2010, ambient HCN mixing ratios ranged from 0.15-1.0 ppbv (±15%), with a mean value of 0.36 ± 0.16 ppbv (1σ). The approximate mean background HCN mixing ratio of 0.20 ± 0.04 ppbv appeared to agree well with tropospheric column measurements reported previously. The GC-FTD HCN measurements were strongly correlated with acetonitrile (CH3CN) measured concurrently with a proton transfer-reaction mass spectrometer (PTR-MS), as anticipated given our understanding that the nitriles share a common primary biomass burning source to the global atmosphere. The nitriles were overall only weakly correlated with carbon monoxide (CO), which is reasonable considering the greater diversity of sources for CO. However, strong correlations with CO were observed on several nights under stable atmospheric conditions and suggest regional combustion-based sources for the nitriles. These results demonstrate that the GC-FTD instrument is

  18. Gas chromatograph analysis on closed air and nitrogen oxide storage atmospheres of recalcitrant seeds of Quercus Alba

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Storage of recalcitrant seeds remains an unsolved problem. This study investigated the quantitative gas analysis of nitrous oxide (N2O) and air atmospheres on the recalcitrant seeds of Quercus alba by using gas chromatograph. Ten seeds were placed in each sealed atmospheric system of air and 98/2% N...

  19. Simultaneous gas-chromatographic determination of four toxic gases generally present in combustion atmospheres. Final report

    SciTech Connect

    Endecott, B.R.; Sanders, D.C.; Chaturvedi, A.K.

    1994-09-01

    Measurement of combustion gases produced by burning aircraft cabin materials poses a continuing limitation for smoke toxicity research. Since toxic effects of gases depend on both their concentrations and duration of exposures, frequent atmosphere sampling is necessary to define the concentration-time curve. A gas chromatographic method was developed for the simultaneous analyses of carbon monoxide (CO), hydrogen sulfide (H2S), sulfur dioxide (SO2), and hydrogen cyanide (HCN). The method utilized an MTI M200 dual-column gas chromatograph (GC) equipped with 4-m molecular sieve-5A and 8-m PoraPlot-U capillary columns and two low-volume, high-sensitivity thermal conductivity detectors. Detectability (ppm)/retention times (seconds) for the gases were: CO (100/28); H2S (50/26); SO2 (125/76); HCN (60/108). The method was effective for determining these gases in mixtures and in the combustion atmospheres generated by burning wool (CO, HCN, and H2S) and modacrylic (CO and HCN) fabrics. Common atmospheric gaseous or combustion products (oxygen, carbon dioxide, nitrogen, water vapor, and other volatiles) did not interfere with the analyses. However, filtration of the combustion atmospheres was necessary to prevent restriction of the GC sampling inlet by smoke particulates. The speed, sensitivity, and selectivity of this method make it suitable for smoke toxicity research and for evaluating performance of passenger protective breathing equipment.

  20. Headspace gas chromatographic method for determination of methyl bromide in food ingredients

    SciTech Connect

    DeVries, J.W.; Broge, J.M.; Schroeder, J.P.; Bowers, R.H.; Larson, P.A.; Burns, N.M.

    1985-11-01

    A headspace gas chromatographic (GC) method, which can be automated, has been developed for determination of methyl bromide. This method has been applied to wheat, flour, cocoa, and peanuts. Samples to be analyzed are placed in headspace sample vials, water is added, and the vials are sealed with Teflon-lined septa. After an appropriate equilibration time at 32 degrees C, the samples are analyzed within 10 h. A sample of the headspace is withdrawn and analyzed on a gas chromatograph equipped with an electron capture detector (ECD). Methyl bromide levels were quantitated by comparison of peak area with a standard. The standard was generated by adding a known amount of methyl bromide to a portion of the matrix being analyzed and which was known to be methyl bromide free. The detection limit of the method was 0.4 ppb. The coefficient of variation (CV) was 6.5% for wheat, 8.3% for flour, 3.3% for cocoa, and 11.6% for peanuts.

  1. Toward a Micro Gas Chromatograph/Mass Spectrometer (GC/MS) System

    NASA Astrophysics Data System (ADS)

    Wiberg, D. V.; Eyre, F. B.; Orient, O.; Chutjian, A.; Garkarian, V.

    2001-01-01

    Miniature mass filters (e.g., quadrupoles, ion traps) have been the subject of several miniaturization efforts. A project is currently in progress at JPL to develop a miniaturized Gas Chromatograph/Mass Spectrometer (GC/MS) system, incorporating and/or developing miniature system components including turbomolecular pumps, scroll type roughing pump, quadrupole mass filter, gas chromatograph, precision power supply and other electronic components. The preponderance of the system elements will be fabricated using microelectromechanical systems (MEMS) techniques. The quadrupole mass filter will be fabricated using an X-ray lithography technique producing high precision, 5x5 arrays of quadrupoles with pole lengths of about 3 mm and a total volume of 27 cubic mm. The miniature scroll pump will also be fabricated using X-ray lithography producing arrays of scroll stages about 3 mm in diameter. The target detection range for the mass spectrometer is 1 to 300 atomic mass units (AMU) with are solution of 0.5 AMU. This resolution will allow isotopic characterization for geochronology, atmospheric studies and other science efforts dependant on the understanding of isotope ratios of chemical species. This paper will discuss the design approach, the current state-of-the art regarding the system components and the progress toward development of key elements. The full system is anticipated to be small enough in mass, volume and power consumption to allow in situ chemical analysis on highly miniaturized science craft for geochronology, atmospheric characterization and detection of life experiments applicable to outer planet roadmap missions.

  2. Fast low-pressure microwave assisted extraction and gas chromatographic determination of polychlorinated biphenyls in soil samples.

    PubMed

    Bruzzoniti, M C; Maina, R; Tumiatti, V; Sarzanini, C; Rivoira, L; De Carlo, R M

    2012-11-23

    A new technology equipment for low-pressure microwave assisted extraction (usually employed for organic chemistry reactions), recently launched in the market, is used for the first time in environmental analysis for the extraction of commercial technical Aroclor mixtures from soil. Certified reference materials of Aroclor 1260, Aroclor 1254 and Aroclor 1242 in transformer oils were used to contaminate the soil samples and to optimize the extraction method as well as the subsequent gas chromatographic electron capture detection (GC-ECD) analytical method. The study was performed optimizing the extraction, the purification and the gas chromatographic separation conditions to enhance the resolution of difficult pairs of congeners (C28/31 and C141/179). After optimization, the recovery yields were included within the range 79-84%. The detection limits, evaluated for two different commercial polychlorinated biphenyl (PCB) mixtures (Aroclor 1260 and Aroclor 1242) were 0.056 ± 0.001 mg/kg and 0.290 ± 0.006 mg/kg, respectively. The method, validated with certified soil samples, was used to analyze a soil sample after an event of failure of a pole-mounted transformer which caused the dumping of PCB contaminated oil in soil. Moreover, the method provides simple sample handling, fast extraction with reduced amount of sample and solvents than usually required, and simple purification step involving the use of solvent (cyclohexane) volumes as low as 5 mL. Reliability and reproducibility of extraction conditions are ensured by direct and continuous monitoring of temperature and pressure conditions. PMID:23084486

  3. Gas chromatographic determination of polysaccharide gums in foods after hydrolysis and derivatization.

    PubMed

    Lawrence, J F; Iyengar, J R

    1985-12-20

    A gas chromatographic method was evaluated for the determination of food grade gums in dairy products, salad dressings and meat sauces. The gums studied were tragacanth, karaya, ghatti, carob, guar, arabic and xanthan gum. The extraction method included removal of fat followed by starch degradation then precipitation of protein. The isolated gums were hydrolysed with trifluoroacetic acid and the resulting neutral monosaccharides converted to their aldonitrile acetate derivatives for determination by gas chromatography. Recoveries from thirteen different commodities averaged 85%. However, the recovery of guar gum from ice cream and cold pack cheese was 42 and 50%, respectively. In a comparison of enzyme hydrolysis and iodine complexation for the removal of starch the former was simpler and provided cleaner extracts than the iodine treatment. Both gave similar results. PMID:4093481

  4. Comparison of a gas chromatographic and colorimetric method for the determination of plasma paracetamol.

    PubMed

    Chambers, R E; Jones, K

    1976-07-01

    Plasma paracetamol levels have generally been determined either by gas chromatography (Stewart and Willis, 1975), which relies on complex equipment, or by spectrophotometry (Knepil, 1974), which can be time-consuming. The introduction by Glynn and Kendal (1975) of a simple colorimetric method based on the reaction of paracetamol with nitrous acid to give 2-nitro-4-acetamidophenol appears to have overcome these disadvantages, thereby providing a suitable procedure for the rapid measurement of plasma paracetamol in cases of overdose. The method was reported to be specific for paracetamol, no interference being caused either by the sulphate and glucuronide conjugates of paracetamol or by a large number of other commonly found drugs. This communication presents the results of a study in which plasma paracetamol levels determined by the colorimetric method were compared with those determined by an established gas chromatographic technique. PMID:952476

  5. Detection system for a gas chromatograph. [. cap alpha. -methylnaphthalene,. beta. -methylnapthalene

    DOEpatents

    Hayes, J.M.; Small, G.J.

    1982-04-26

    A method and apparatus are described for the quantitative analysis of vaporizable compounds, and in particular of polycyclic aromatic hydrocarbons which may be induced to fluoresce. The sample to be analyzed is injected into a gas chromatography column and is eluted through a narrow orifice into a vacuum chamber. The free expansion of the eluted sample into the vacuum chamber creates a supersonic molecular beam in which the sample molecules are cooled to the extent that the excited vibrational and rotational levels are substantially depopulated. The cooled molecules, when induced to fluoresce by laser excitation, give greatly simplified spectra suitable for analytical purposes. The laser induced fluorimetry provides great selectivity, and the gas chromatograph provides quantitative transfer of the sample to the molecular beam. 3 figures, 2 tables.

  6. Gas chromatographic determination of sulfuric acid and application to urinary sulfate.

    PubMed

    Masuoka, N; Ubuka, T; Kinuta, M; Yoshida, S; Taguchi, T

    1988-10-01

    A new gas chromatographic method for the determination of sulfate was developed. In this method, sulfate was quantitatively converted to a volatile derivative, dimethyl sulfate, by a two-step procedure. First, sulfate was converted to silver sulfate by reaction with silver oxide, and then to dimethyl sulfate by reaction with methyl iodide. The derivative was analyzed by gas chromatography. Methyl methanesulfonate was used as an internal standard. The method was applied to the determination of total urinary sulfate. Phosphate and chloride ions, which interfered with the present method, were eliminated with the use of basic magnesium carbonate and an excess of silver oxide, respectively. Recovery was over 96% when 5 to 40 mumol/ml of sulfate was added to human urine samples. PMID:3223336

  7. Isotope Separation in Concurrent Gas Centrifuges

    NASA Astrophysics Data System (ADS)

    Bogovalov, S. V.; Borman, V. D.

    An analytical equation defining separative power of an optimized concurrent gas centrifuge is obtained for an arbitrary binary mixture of isotopes. In the case of the uranium isotopes the equation gives δU= 12.7(V/700 m/s)2(300 K/T)L, kg SWU/yr, where L and V are the length and linear velocity of the rotor of the gas centrifuge, T is the temperature. This formula well agrees with an empirical separative power of counter current gas centrifuges.

  8. Comparison of different statistical approaches to evaluate the orthogonality of chromatographic separations: application to reverse phase systems.

    PubMed

    Al Bakain, Ramia; Rivals, Isabelle; Sassiat, Patrick; Thiébaut, Didier; Hennion, Marie-Claire; Euvrard, Guillaume; Vial, Jérôme

    2011-05-20

    Selectivity of phase system is of primary concern when designing a bidimensional chromatographic system and looking for the highest degree of orthogonality between the two separations. Several statistical or geometrical criteria can potentially be used to measure the degree of orthogonality. A comparison of eight candidate criteria has been carried out in this study. Analysis of variance (ANOVA) was used to evaluate the relevance of each criterion and its ability to reveal the significance of the influence of factors like pH, stationary phase, and organic modifier. Experimentally, a set of 32 chromatographic systems was evaluated by the same generic gradient with 63 probe solutes, likely to be present in biological and/or environmental samples and covering a wide range of physico-chemical properties: acidic, basic and neutral compounds with different pKa, molecular mass and hydrophobicity (logP). Each chromatographic system was defined by the nature of the stationary phase (8 different silica or grafting chemistries), the pH of the aqueous fraction of the mobile phase (2.5 or 7.0) and the nature of the organic modifier (acetonitrile or methanol). The orthogonality of the 496 couples of chromatographic systems was evaluated and ranked using the eight different approaches: the three correlation coefficients (Pearson, Spearman and Kendall), two geometric criteria characterizing the coverage of the 2D separation space, Slonecker's information similarity and two chi-square statistics of independence between normalized retention times. In fact, there were only seven distinct criteria, since we established the analytical equivalence between the rankings with the likelihood ratio statistics and Slonecker's information similarity. Kendall's correlation coefficient appeared to be the best measure of orthogonality since, according to ANOVA, it exhibited the highest sensitivity to all experimental factors. The chi-square measures, and hence Slonecker's information similarity

  9. New chromatographic materials for the separation and concentration of uranium from environmental matrices

    SciTech Connect

    Horwitz, E.P.; Dietz, M.L.; Chiarizia, R.; Diamond, H.

    1991-01-01

    Extraction chromatography, in which an inert support is impregnated with an extractant solution to form a chromatographic resin, combines the specificity of extraction with the ease of operation of an ion exchange column, thereby overcoming the principal drawbacks of the two methods when used alone. Previous work in this laboratory on the design of selective extractants for use in nuclear fuel reprocessing and in nuclear waste treatment has led to the development of several new phosphorus-based neutral organic extractants. In this report, we examine the use of two of these materials as stationary phases in extraction chromatography for the isolation of uranium from environmental samples. 2 refs., 2 figs., 1 tab.

  10. Comparison of nano and conventional liquid chromatographic methods for the separation of (+)-catechin-ethyl-malvidin-3-glucoside diastereoisomers.

    PubMed

    Kučera, Lukáš; Fanali, Salvatore; Aturki, Zeineb; Pospíšil, Tomáš; Bednář, Petr

    2016-01-01

    Nano-liquid chromatography and conventional HPLC were used for the separation of diastereomers of (+)-catechin-ethyl-malvidin-3-glucoside. Those bridged anthocyanin dyes were obtained by reaction of (+)-catechin with malvidin-3-glucoside in the presence of acetaldehyde. Both diastereomers were isolated with semipreparative chromatography and their structures were confirmed by nuclear magnetic resonance and mass spectrometry. In-laboratory prepared capillary columns packed with fully porous particles Chromosphere C18, dp=3μm, core-shell particles Kinetex C18, dp=2.6μm (100μm i.d.) and monolithic column Chromolith CapRod (100μm i.d.) were used for the separation of (+)-catechin, malvidin-3-glucoside and both diastereomers. Chromosphere C18 stationary phase provided the best chromatographic performance. Mobile phase containing water:acetonitrile (80:20) acidified with trifluoroacetic acid (0.1%, v/v/v) was used in an isocratic elution mode with a flow rate of 360nLmin(-1). Separation of studied compounds was achieved in less than 7min under optimized conditions. The nano-liquid chromatographic method and a conventional HPLC one using the same fully porous particles (Chromosphere C18, 3μm, 100mm×4.6mm) were compared providing higher separation efficiency with the first analytical method and similar selectivity. A better peak symmetry and higher resolution of the studied diastereomers was achieved by conventional chromatography. Nevertheless, nano-liquid chromatography appeared to be useful for the separation of complex anthocyanin dyes and can be utilized for their analysis in plant and food micro-samples. The developed method was used for analysis of red wine grape pomace. PMID:26433264