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1

Gas-liquid chromatography in lunar organic analysis.  

NASA Technical Reports Server (NTRS)

Gas-liquid chromatography (GLC) is a powerful and sensitive method for the separation and detection of organic compounds at nanogram levels. The primary requirement for successful analyses is that the compounds of interest must be volatile under the chromatographic conditions employed. Nonvolatile organic compounds must be converted to volatile derivatives prior to analysis. The derivatives of choice must be both amenable to chromatographic separation and be relatively stable. The condition of volatility necessitates the development of efficient derivatization reactions for important groups of compounds as amino acids, carbohydrates, nucleosides, etc. Trimethylsilylation and trifluoroacetylation represent specific areas of recent prominence. Some relevant practical aspects of GLC are discussed.

Gehrke, C. W.

1972-01-01

2

Quantitative Fatty Acid Analysis of Milk Fat by Gas-Liquid Chromatography  

Microsoft Academic Search

A procedure was developed for quantitative analysis of the fatty acids of milk fat. Methyl esters of the acids were prepared by methanolysis, extracted with ethyl chloride, and separated by gas-liquid chromatography (GLC), with diethylene glycol succinate as liquid phase. Known mixtures of methyl esters were used in determining factors for correction of peak areas for losses from evaporation of

L. M. Smith

1961-01-01

3

Analysis of polychlorinated biphenyls by high-performance liquid chromatography and capillary gas-liquid chromatography.  

PubMed

Seventy fractions were obtained by vacuum distillation of a PCB mixture containing 42% of chlorine. Four of these fractions were chosen, the composition of which covered the whole of the observed region, and analysed by means of high-performance liquid chromatography (HPLC) on silica gel using n-pentane as the mobile phase and capillary gas-liquid chromatography (GLC) using OV-101 and Carbowax 20M as stationary phases at 200 degrees C. The chosen distillation fractions were further prepared by HPLC, each yielding 10-14 samples. Individual PCB standards and all samples were analysed by HPLC and capillary GLC. These procedures permitted the identification of those compounds which are eluted simultaneously under the conditions used in either HPLC or capillary GLC alone. PMID:410818

Krupcík, J; Kríz, J; Pr?sová, D; Suchánek, P; Cervenka, Z

1977-11-11

4

Quantitative fatty acid analysis of vegetable oils by gas-liquid chromatography  

Microsoft Academic Search

Summary  The fatty acid composition of a number of vegetable oils and of two synthetic mixtures of methyl esters are compared by gas-liquid\\u000a chromatography and by standard methods. The calculated iodine values from G.L.P.C. results are in good agreement with measured\\u000a iodine values and are indicative of the reliability of the G.L.P.C. values. Standard methods gave lower values for linoleic\\u000a acid

B. M. Craig; N. L. Murty

1959-01-01

5

Mixed Stationary Liquid Phases for Gas-Liquid Chromatography.  

ERIC Educational Resources Information Center

Describes a laboratory technique for use in an undergraduate instrumental analysis course that, using the interpretation of window diagrams, prepares a mixed liquid phase column for gas-liquid chromatography. A detailed procedure is provided. (BT)

Koury, Albert M.; Parcher, Jon F.

1979-01-01

6

The identification and quantitative analysis of abscisic acid in plant extracts by gas-liquid chromatography  

Microsoft Academic Search

New techniques are described which permit the quantitative analysis of microgram quantities of abscisic acid in plant extracts by gas chromatography. Presumptive methyl abscisate peaks on gas chromatograms are positively identified by photosensitised isomerisation to methyl 2-trans-abscisate. Losses of abscisic acid during pre-purification are corrected by using 2-trans-abscisic acid as an internal standard.

J. R. Lenton; V. M. Perry; P. F. Saunders

1971-01-01

7

Polycyclic aromatic hydrocarbons of coal fly ash: Analysis by gas?liquid chromatography using nematic liquid crystals  

Microsoft Academic Search

The seasonal variations over a period of 12 m in the amounts of polycyclic aromatic hydrocarbons (PAH) in fly?ash samples collected from the electrostatic precipitator of a thermal power plant have been studied. PAH generally did not show much seasonal variation. The gas?liquid chromatographic (GLC) analysis of benezene extract of fly ash showed the presence of 28 polyaromatic hydrocarbons, of

V. K. Srivastava; P. K. Srivastava; U. K. Misra

1985-01-01

8

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

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Gas liquid chromatography system for clinical use. ...§ 862.2250 Gas liquid chromatography system for clinical use. ...Identification. A gas liquid chromatography system for clinical...

2010-04-01

9

Quantification of milk fat in chocolate fats by triacylglycerol analysis using gas-liquid chromatography.  

PubMed

The development and in-house testing of a method for the quantification of milk fat in chocolate fats is described. A database consisting of the triacylglycerol profiles of 310 genuine milk fat samples from 21 European countries and 947 mixtures thereof with chocolate fats was created under a strict quality control scheme using 26 triacylglycerol reference standards for calibration purposes. Out of the individual triacylglycerol fractions obtained, 1-palmitoyl-2-stearoyl-3-butyroyl-glycerol (PSB) was selected as suitable marker compound for the determination of the proportion of milk fat in chocolate fats. By using PSB values from the standardized database, a calibration function using simple linear regression analysis was calculated to be used for future estimations of the milk fat content. A comparison with the widely used butyric acid method, which is currently used to determine the milk fat content in nonmilk fat mixtures, showed that both methods were equivalent in terms of accuracy. The advantage of the presented approach is that for further applications, i.e., determination of foreign fats in chocolate fats, just a single analysis is necessary, whereas for the same purpose, the C4 method requires two different analytical methods. PMID:17394333

Buchgraber, Manuela; Androni, Simona; Anklam, Elke

2007-05-01

10

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

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Gas liquid chromatography system... MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES...Instruments § 862.2250 Gas liquid chromatography system... (a) Identification. A gas liquid...

2011-04-01

11

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

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Gas liquid chromatography system... MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES...Instruments § 862.2250 Gas liquid chromatography system... (a) Identification. A gas liquid...

2013-04-01

12

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

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Gas liquid chromatography system... MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES...Instruments § 862.2250 Gas liquid chromatography system... (a) Identification. A gas liquid...

2014-04-01

13

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

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Gas liquid chromatography system... MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES...Instruments § 862.2250 Gas liquid chromatography system... (a) Identification. A gas liquid...

2012-04-01

14

Identification of peaks in gas-liquid chromatography  

Microsoft Academic Search

Some of the known principles of gas-liquid chromatography are reviewed. Application of the equivalent chain length (ECL) method\\u000a to identification of complex molecules, and to prediction of structures of unknowns, is described in detail.

T. K. Miwa

1963-01-01

15

Gas-liquid chromatography for fenvalerate residue analysis: in vivo alterations in the acetylcholinesterase activity and acetylcholine in different tissues of the fish, Labeo rohita (Hamilton).  

PubMed

The disruption of acetylcholinesterase activity (AChE) in the freshwater fish, Labeo rohita is demonstrated in the present study using acetylthiocholine iodide as substrate. L. rohita on exposure to lethal (6 microg/L) and sub-lethal (0.75 microg/L) concentrations of fenvalerate showed time- and dose-dependent inhibition in the activity of AChE, suggesting a decrease in the cholinergic transmission and consequent accumulation of acetylcholine (ACh) in the tissues (brain, gill, liver, and muscle) leading to continuous nerve impulses, causing prolonged muscle contraction which, as a consequence, causes paralysis and results in death. These also have lead to behavioral changes and create widespread disturbance in the normal neural physiology of the fish. Residue analysis using a gas-liquid chromatography technique (GLC) revealed that highest quantity of fenvalerate accumulated in gill followed by liver and muscle under lethal concentrations, whereas in sub-lethal concentrations muscle accumulated the highest concentration followed by gill and liver. The results suggest that in a biomonitoring program AChE activity can be a good diagnostic tool for assessing fenvalerate toxicity. The lipophilic nature of fenvalerate is of concern, since L. rohita is an important staple fish species, which may lead to the phenomenon of biomagnification. PMID:19778241

David, Muniswamy; Patil, Vineetkumar K; Chebbi, Sameer G; Marigoudar, Shambangouda R; Chittaragi, Jagadeesh B; Halappa, Ramesh

2009-09-01

16

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

USGS Publications Warehouse

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

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

1977-01-01

17

Gas-liquid chromatography with a volatile "stationary" liquid phase.  

PubMed

A unique type of gas-liquid chromatography is described in which both mobile and "stationary" phases are composed of synthetic mixtures of helium and carbon dioxide. At temperatures below the critical point of the binary mixture and pressures above the vapor pressure of pure liquid carbon dioxide, helium and carbon dioxide can form two immiscible phases over extended composition ranges. A binary vapor phase enriched in helium can act as the mobile phase for chromatographic separations, whereas a CO2-rich liquid in equilibrium with the vapor phase, but condensed on the column wall, can act as a pseudostationary phase. Several examples of chromatographic separations obtained in "empty" capillary columns with no ordinary stationary liquid phase illustrate the range of conditions that produce such separations. In addition, several experiments are reported that confirm the proposed two-phase hypothesis. The possible consequences of the observed chromatographic phenomenon in the field of supercritical fluid chromatography with helium headspace carbon dioxide are discussed. PMID:12033313

Wells, P S; Zhou, S; Parcher, J F

2002-05-01

18

Preparation of pure microbiological samples for pyrolysis gas-liquid chromatography studies  

NASA Technical Reports Server (NTRS)

Bacterial samples were prepared for pyrolysis gas-liquid chromatography using cells grown on membrane filters. Pyrochromatograms were reproducible when cells harvested from the filters were pyrolyzed without being washed.

Oxborrow, G. S.; Fields, N. D.; Puleo, J. R.

1976-01-01

19

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

PubMed

Unknown compounds detected in Ardea herodias tissues are identified by gas-liquid chromatography-mass spectrometry as residues of octachlorostyrene. Heptachlorostyrene and hexachlorostyrene were tentatively identified. PMID:833106

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

1977-01-01

20

Characterization of Bacillus subtilis, Bacillus pumilus, Bacillus licheniformis, and Bacillus amyloliquefaciens by Pyrolysis Gas-Liquid Chromatography, Deoxyribonucleic Acid-Deoxyribonucleic Acid Hybridization, Biochemical Tests, and API Systems  

Microsoft Academic Search

Eight strains each of Bacillus subtilis, Bacillus pumilus, Bacillus lichenifor- mis, and Bacillus amyloliquefaciens were analyzed by using pyrolysis gas-liquid chromatography. Statistical analysis with canonical variates gave four well-sep- arated groups, which represented the four species. Further analysis of the same strains by deoxyribonucleic acid-deoxyribonucleic acid hybridization and API identification systems confirmed the discrimination obtained with pyrolysis gas- liquid chromatography.

A. G. O'DONNELL; J. R. NORRIS; R. C. W. BERKELEY; D. CLAUS; T. KANEK; N. A. LOGAN

21

Quantitative Estimation of Peak Areas in Gas-Liquid Chromatography  

Microsoft Academic Search

QUANTITATIVE estimation of peak areas on gas-liquid chromatograms has been carried out by a variety of methods, which include triangulation, cutting out the peak areas and weighing the cut paper, planimeter tracing and use of an integrator built into the recorder. A new method recently proposed by Bartlet and Smith1 is based on evidence that the peaks obtained with a

K. K. Carroll

1961-01-01

22

The differentiation and assay of vitamins D2 and D3 by gas–liquid chromatography  

PubMed Central

1. A method is described for the differentiation and determination of as little as 0·2?g. of vitamins D2 and D3 by gas–liquid chromatography. 2. The vitamins are converted by treatment with antimony trichloride into isovitamins D2 and D3, which show single, separate peaks on gas–liquid chromatography, unlike the unmodified vitamins, which give twin peaks due to the formation of pyro and isopyro derivatives. 3. Since isovitamins D2 and D3 remain together in all steps of the procedure except during gas–liquid chromatography, one may be used as an internal standard for the other. 4. The use of an internal standard reduces the importance of loss during sample preparation and increases precision. 5. The application of the method to biological materials is demonstrated. PMID:4287184

Murray, T. K.; Day, K. C.; Kodicek, E.

1966-01-01

23

Fatty acids of cows' milk. A. Techniques employed in supplementing gas-liquid chromatography for identification of fatty acids  

Microsoft Academic Search

Milk fat methyl esters were subjected to distillation and silicic acid column chromatography to provide fractions of less\\u000a complexity for gas-liquid chromatographic analysis. It was still necessary however to employ supplemental techniques for identification.\\u000a Chromatograms were obtained with polyester columns of different polarity on all the fractions and necessary reference samples.\\u000a While many of the components were identified in the

Paul Magidman; S. F. Herb; R. A. Barford; R. W. Riemenschneider

1962-01-01

24

The Separation and Identification of Straight Chain Hydrocarbons: An Experiment Using Gas-Liquid Chromatography.  

ERIC Educational Resources Information Center

An experiment using gas-liquid chromatography is discussed, introducing the student to concept of dead volume and its measurement, idea and use of an internal reference compound, and to linear relationship existing between measurements of a separation on two different stationary phases. (Author/SK)

Benson, G. A.

1982-01-01

25

Optimal data processing procedure for automatic bacterial identification by gas-liquid chromatography of cellular fatty acids.  

PubMed Central

Gas-liquid chromatography of cellular fatty acids was used in automatic identification of clinical bacterial isolates. The intraspecies variation in the occurrence of fatty acids and the variation in the relative gas-liquid chromatography peak areas of different fatty acids were evaluated and compared with the relative peak areas of these acids. A new chromatogram comparison method involving the use of an exponential function was developed to adjust to data variation optimally. This method was compared with several previously published methods of correlation analysis with data from representative clinical bacteriological isolates. The efficacies of the methods in separating different bacterial species into distinct clusters were compared. The new exponential function method was superior to the others both in its ability to separate species into different clusters and in giving a greater degree of identity to strains within a proper cluster. The results indicate that the gas-liquid chromatography of bacterial cellular fatty acids can be used effectively in the identification of clinically isolated bacteria. However, the usefulness of the analysis depends on the comparison method used and on its ability to cope with data variations. PMID:3183021

Eerola, E; Lehtonen, O P

1988-01-01

26

Gas-liquid chromatography-mass spectrometry of hydroxylated octadecanols derived from hydroxylated stearic acids  

Microsoft Academic Search

A gas-liquid chromatographic-mass spectro- metric method of determining the position of oxygen atoms on polyfunctional fatty acids has been explored. The method con- sists of reduction of keto, hydroperoxy, epoxy, and carboxylic acid groups with LiAIH4 to the corresponding alcohols; tri- methylsilylation with bis(trimethylsily1) acetamide; and analysis by means of the combined gas-liquid chromatograph-mass spectrometer.

WALTER J. ESSELMAN

27

DETERMINATION OF PENTACHLOROPHENOL IN MARINE BIOTA AND SEA WATER BY GAS-LIQUID CHROMATOGRAPHY AND HIGH-PRESSURE LIQUID CHROMATOGRAPHY  

EPA Science Inventory

A method is described for measuring pentachlorophenol (PCP) in samples from the estuarine environment. Gas-liquid chromatography (GLC) is used to determine PCP residues in tissues as low as 0.01 ppm by formation of the ethyl diazohydrocarbon derivative, followed by Florisil clean...

28

Characterization of unsaturated fatty acids by gas-liquid chromatography  

Microsoft Academic Search

The equivalent chain length (ECL) has been determined on 79 methyl esters of unsaturated fatty acids and on 7 ethyl esters\\u000a by gas chromatography. Ethylene glycol succinate (EGS), diethylene glycol succinate, ?-cyclodextrin acetate and Apiezon L\\u000a were chosen as the liquid phases to be used. For methyl esters of mono- and polyenoic acids, the differences between ECL on\\u000a EGS and

H. H. Hofstetter; N. Sen; R. T. Holman

1965-01-01

29

Determination of methenamine in biological samples by gas-liquid chromatography.  

PubMed

Methenamine (hexamethylenetetramine), a urinary disinfectant, was determined in human plasma and urine by gas-liquid chromatography with a short (10 m) open-bore glass capillary column (split ratio 1:20) and nitrogen-selective detector. An almost quantitative recovery (92.1%) was achieved by simple dilution of water-containing samples (0.5 ml) with acetone (4.5 ml). After centrifugation an aliquot (2 microliter) of the supernatant was injected into the gas chromatograph. Selectivity and sensitivity of the nitrogen detector allowed the quantitation of unchanged methenamine in plasma and urine up to 24 h after a single therapeutic dose of 1 g. Reproducibility of the method was 7.6 and 2.1% (C.V.) in serum and urine, respectively. The time required for the analysis of one sample was approx. 2 min. Due to the simple extraction and short analysis time it was possible to analyze the samples concurrently with sample taking. Absorption of standard tablets and an enterosoluble preparation of methenamine hippurate was compared. PMID:7364903

Nieminen, A L; Kangas, L; Anttila, M; Hautoniemi, L

1980-01-11

30

Gas-liquid chromatography of triglycerides from erucic acid oils and fish oils.  

PubMed

By critically selecting optimum operating conditions, quantitative gas-liquid chromatography of triglycerides has been extended to molecules containing substantial amounts of C(20), C(22), and C(24) fatty acids. The triglycerides of four erucic acid oils (water cress, rapessed, nasturtium, andLunaria annua) and two fully hydrogenated fish oils (menhaden and tuna) have been quantitatively analyzed by this technique. The average fatty acid chain length calculated from the triglyceride composition of each oil agreed closely with that determined by GLC of its respective methyl esters. Several conclusions about the triglyceride composition of the fats analyzed are discussed. PMID:17805614

Harlow, R D; Litchfield, C; Reiser, R

1966-05-01

31

Using reverse gas-liquid chromatography to determine the thermodynamic functions of sorption in a system of constant volume  

NASA Astrophysics Data System (ADS)

A static "ideal gas phase-nonvolatile liquid" system of constant volume in which the volatile component (sorbate) is redistributed is compared to a chromatographic system under conditions corresponding to equilibrium gas-liquid chromatography. The basis for calculating the thermodynamic characteristics of sorption using chromatographic data is described. The standard conditions and way of expressing the constant of interphase sorbate distribution are specified.

Onuchak, L. A.; Kudryashov, S. Yu.

2014-10-01

32

Determination of fatty acid composition and total trans fatty acids of Turkish biscuits by capillary gas-liquid chromatography  

Microsoft Academic Search

In this research, fatty acid composition and total trans fatty acid contents of six types of biscuit produced by four different Turkish companies were determined by capillary gas-liquid\\u000a chromatography. Total fat contents of the biscuit samples ranged between 8.5% and 26.0%. The highest fat content was determined\\u000a in sesame biscuits (average 24.4%) and the lowest in petit beurre biscuits (average

Orhan Daglioglu; Murat Tasan; Baris Tuncel

2000-01-01

33

Scaling analysis of gas-liquid two-phase flow pattern in microgravity  

NASA Technical Reports Server (NTRS)

A scaling analysis of gas-liquid two-phase flow pattern in microgravity, based on the dominant physical mechanism, was carried out with the goal of predicting the gas-liquid two-phase flow regime in a pipe under conditions of microgravity. The results demonstrated the effect of inlet geometry on the flow regime transition. A comparison of the predictions with existing experimental data showed good agreement.

Lee, Jinho

1993-01-01

34

Determination of topanol antioxidants in methacrylates using capillary gas-liquid chromatography.  

PubMed

This paper presents a method to identify and determine topanol A and topanol O antioxidants in methylmethacrylate and 11-bromoundecylmethacrylate. The method is both simple and rapid. Analysis is performed on a 10 m x 0.53 mm I.D. HP-1 capillary gas chromatography column with a temperature gradient and a high carrier gas flow-rate (16.5 ml/min). Quantitation is by internal standardisation. Validation of the method is described for both topanols at concentrations of approximately 50 ppm in methylmethacrylate and 250 ppm in 11-bromoundecylmethacrylate. PMID:1400842

Smith, I D; Waters, D G

1992-04-10

35

Analysis of video images used to study gas-liquid transfer  

E-print Network

Analysis of video images used to study gas-liquid transfer S.P.Gurden1, E.M.Lage2, C.G.de Faria1, I using a standard color video camera. Prior to analysis using models such as PCA and PARAFAC-mail: spgurden@iqm.unicamp.br Introduction Video images and multivariate models are used here to provide

Ferreira, Márcia M. C.

36

Chromatographic studies on fatty acid dinners: Gas-liquid chromatography, high performance liquid chromatography and thin-layer chromatography  

Microsoft Academic Search

Methods for separation of various structural entities of dimers from heated fats and oils are not yet available. A series\\u000a of dimers, representative of these, which may be formed in thermal oxidative reactions of fats and oils have recently been\\u000a made available. In this study, the results of the analysis of a mixture of standard synthetic dimers, differing in polarity

C. N. Chrlslopoulouo; E. G. Perklnsb

1989-01-01

37

Statistical analysis of parameter prediction of various military fuel samples utilizing their gas liquid chromatograms. Interim technical report  

SciTech Connect

There is a research effort that envisions having a vehicle mounted petroleum analysis system that could travel close to the frontlines and would provide rapid test results. This system would quicken results feedback time and increase the scope of analyses by using new technologies that could predict several fuel properties and parameters. One approach under consideration for use in this system is Gas Liquid-Phase Chromatography (GLC). Previous results using GLC data from an oven profile that resulted in a sixty-minute analysis time resulted in a 100% correct classification as to fuel type and predictions of the 10%, 50%, and 90%, and final boiling point distillation temperatures; and the densities of the samples with relatively low errors of prediction. To reduce the analysis test time, oven profiles were developed to give a twelve-minute GLC analysis time and the statistical analysis of the two oven profiles were compared to determine if the shorter test time would yield comparable results.

Minus, D.D.

1996-02-01

38

Direct estimation of carbaryl by gas liquid chromatography with nitrogen phosphorus detection.  

PubMed

A simple and efficient analytical method was standardized for the estimation of residues of carbaryl in various substrates comprising grape berries, kinnow pulps, kinnow rind and soil. The samples were refluxed using mixture of methanol: 0.5 N HCl (1:1 v/v); diluted with brine solution, partitioned into chloroform and dried over anhydrous sodium sulfate. Further the samples were treated with anhydrous magnesium sulfate and primary secondary amine. Final clear extracts were concentrated under vacuum and reconstituted the volume into acetone. The residues were estimated directly on gas liquid chromatograph equipped with nitrogen phosphorus detection system equipped with a capillary column packed with 5 % diphenyl 95 % dimethyl polysiloxane non-polar phase. A consistent recovery from 82 % to 97 % for carbaryl was observed when samples were spiked at levels ranging from 0.05 to 1.00 mg kg(-1). The limit of quantification of the method was worked out to be 0.05 mg kg(-1) for grape berries, kinnow pulp, kinnow rind and soil. PMID:22487961

Battu, Raminderjit Singh; Mandal, Kousik; Urvashi; Pandher, Suneet; Takkar, Reenu; Singh, Balwinder

2012-07-01

39

Quantitation of 1,4-Benzoxazin-3-ones in Maize by Gas-Liquid Chromatography 1  

PubMed Central

A gas-liquid chromatographic (GLC) procedure is reported for the quantitation of the trimethylsilyl (TMS) derivatives of substituted 2-hydroxy-2H-1,4-benzoxazin-3(4H)-ones (2-hydroxy-2H-1,4-benzoxazin-3(4H)-one[HBOA]; 2-hydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one[HMBOA];2,4- dihydroxy-2H-1,4-benzoxazin-3(4H)-one[DIBOA]; 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one[DIMBOA]; and 2,4-dihydroxy-7,8-dimethoxy-2H-1,4-benzoxazin-3(4H)-one[DIM 2BOA]) found in maize (Zea mays L.) extracts. Derivatized samples were chromatographed on columns with liquid phases of 2% DC-11 and 3% OV-17 and detected by flame ionization. Internal standards were methyl palmitate and methyl stearate on DC-11 and methyl behenate on OV-17. Detector response was linear to at least 5 nanomoles for TMS2-HBOA and TMS2-DIBOA and to 19 nanomoles for TMS2-DIMBOA. Standard errors of 2% or less were obtained when four replicate samples were analyzed. For each of the 15 maize lines examined, the amount of DIMBOA determined by GLC was directly proportional to the amount of ferric chloride-reactive material determined colorimetrically. PMID:16660666

Woodward, Michael D.; Corcuera, Luis J.; Helgeson, John P.; Kelman, Arthur; Upper, Christen D.

1979-01-01

40

Simulating Retention in Gas-Liquid Chromatography: Benzene, Toluene, and Xylene Solutes  

SciTech Connect

Accurate predictions of retention times, retention indices, and partition constants are a long sought-after goal for theoretical studies in chromatography. Although advances in computational chemistry have improved the understanding of molecular interactions, little attention has been focused on chromatography, let alone calculations of retention properties. Configurational-bias Monte Carlo simulations in the isobaric-isothermal Gibbs ensemble were used to investigate the partitioning of benzene, toluene, and the three xylene isomers between a squalane liquid phase and a helium vapor phase. The united-atom representation of the TraPPE (Transferable Potentials for Phase Equilibria) force field was used for all solutes and squalane. The Gibbs free energies of transfer and Kovats retention indices of the solutes were calculated directly from the partition constants (which were averaged over several independent simulations). While the calculated Kovats indices of benzene and toluene at T = 403 K are significantly higher than their experimental counterparts, much better agreement is found for the xylene isomers at T = 365 K.

WICK,COLLIN D.; MARTIN,MARCUS G.; SIEPMANN, J. ILJA; SCHURE,MARK R.

2000-07-12

41

Possible use of frequency-pulse-modulated electron capture gas-liquid chromatography to identify septic and aseptic causes of pleural effusions.  

PubMed Central

Frequency-pulse-modulated electron capture gas-liquid chromatography was used in conjunction with appropriate derivatization procedures to obtain chromatograms from extracts of pleural effusions. These chromatograms were used to rapidly classify the various types of pleural effusions. With this method we have been able to distinguish among a limited number of effusions caused by congestive heart failure, Mycobacterium tuberculosis, and some other types of bacterial empyemas and pleural effusions. PMID:701463

Brooks, J B; Craven, R B; Schlossberg, D; Alley, C C; Pitts, F M

1978-01-01

42

Evaluation and Quantitation of Intact Wax Esters of Human Meibum by Gas-Liquid Chromatography-Ion Trap Mass Spectrometry  

PubMed Central

Purpose. Wax esters (WE) of human meibum are one of the largest group of meibomian lipids. Their complete characterization on the level of individual intact lipid species has not been completed yet. We obtained detailed structural information on previously uncharacterized meibomian WE. Methods. Intact WE were separated and analyzed by means of high-temperature capillary gas-liquid chromatography (GLC) in combination with low voltage (30 eV) electron ionization ion trap mass spectrometry (ITMS). 3D (mass-to-charge ratio [m/z] versus lipid sample weight versus signal intensity) calibration plots were used for quantitation of WE. Results. We demonstrated that GLC-ITMS was suitable for analyzing unpooled/underivatized WE collected from 14 individual donors. More than 100 of saturated and unsaturated WE (SWE and UWE, respectively) were detected. On average, UWE represented about 82% of the total WE pool. About 90% of UWE were based on oleic acid, while less than 10% were based on palmitoleic acid. The amounts of poly-UWE were <3% of their mono-UWA counterparts. SWE were based primarily on C16–C18 fatty acids (FA) in overall molar ratios of 22:65:13. A pool of C16:0-FA was comprised of a 20:80 (mol/mol) mixture of straight chain and iso-branched isomers, while the corresponding ratio for C18:0-FA was 43:57. Interestingly, C17:0-FA was almost exclusively branched, with anteiso- and iso-isomers found in a ratio of 93:7. Conclusions. GLC-ITMS can be used successfully to analyze more than 100 individual species of meibomian WE, which were shown to comprise 41 ± 8% (wt/wt) of meibum, which made them the largest group of lipids in meibum. PMID:22531701

Butovich, Igor A.; Arciniega, Juan C.; Lu, Hua; Molai, Mike

2012-01-01

43

Determination of brominated vegetable oils in soft drinks by gas liquid chromatography  

Microsoft Academic Search

A method is described for the qualitative and quantitative determination of brominated vegetable oils in soft drinks. The\\u000a procedure involves treatment of the brominated oils with sodium methoxide followed by GLC analysis of the resulting methyl\\u000a esters using methyl pentadecanoate as internal standard. Recoveries on known amounts of these oils ranged between 93.7% and\\u000a 102.4%. The technique, applied to several

H. B. S. Conacher; R. K. Chadha; M. R. Sahasrabudhe

1969-01-01

44

Retention in gas-liquid chromatography with a polyethylene oxide stationary phase: molecular simulation and experiment.  

PubMed

Configurational-bias Monte Carlo simulations in the isobaric-isothermal Gibbs ensemble were carried out to investigate the partitioning of normal alkanes, primary and secondary alcohols, symmetric alkyl ethers and arenes between a helium vapor phase and a polyethylene oxide stationary phase (M(W)=382 g mol(-1)). The united-atom version of the transferable potentials for phase equilibria force field was used to model all solutes, polyethylene oxide and helium. The Gibbs free energies of transfer and Kovats retention indices of the solutes were calculated directly from the partition constants at two different temperatures, 353 and 393 K. Chromatographic experiments on a Carbowax 20M retentive phase were performed for the same set of solutes and temperatures ranging from 333 to 413 K. The predicted retention indices for alcohols, ethers and arenes are overestimated by about 120, 70 and 20 retention index units, respectively, pointing to an overestimation of the first-order electrostatic interactions in the model system. Molecular-level analysis shows that hydrogen-bonding and dipole-dipole interactions lead to orientational ordering for the alcohol and ether analytes, whereas the weaker dipole-quadrupole interactions for the arene solutes are not sufficient to induce orientational ordering. The retention indices of alcohols and ethers decrease with increasing temperature because of the large entropic cost of hydrogen-bonding and orientational ordering. In contrast, the retention indices for arenes increase with increasing temperature because the entropic cost of cavity formation is smaller for arenes than for comparable alkanes. PMID:16814798

Sun, Li; Siepmann, J Ilja; Klotz, Wendy L; Schure, Mark R

2006-09-01

45

Analysis of spatial and temporal spectra of liquid film surface in annular gas-liquid flow  

NASA Astrophysics Data System (ADS)

Wavy structure of liquid film in annular gas-liquid flow without liquid entrainment consists of fast long-living primary waves and slow short-living secondary waves. In present paper, results of spectral analysis of this wavy structure are presented. Application of high-speed LIF technique allowed us to perform such analysis in both spatial and temporal domains. Power spectra in both domains are characterized by one-humped shape with long exponential tail. Influence of gas velocity, liquid Reynolds number, liquid viscosity and pipe diameter on frequency of the waves is investigated. When gravity effect is much lesser than the shear stress, similarity of power spectra at different gas velocities is observed. Using combination of spectral analysis and identification of characteristic lines of primary waves, frequency of generation of secondary waves by primary waves is measured.

Alekseenko, Sergey; Cherdantsev, Andrey; Heinz, Oksana; Kharlamov, Sergey; Markovich, Dmitriy

2013-09-01

46

Characterization of Mycobacterium paratuberculosis by gas-liquid and thin-layer chromatography and rapid demonstration of mycobactin dependence using radiometric methods.  

PubMed Central

Thirty-six Mycobacterium paratuberculosis isolates of bovine, caprine, and ovine origins were evaluated by using gas-liquid chromatography (GLC), thin-layer chromatography (TLC), and BACTEC 7H12 Middlebrook TB medium (12A; Johnston Laboratories, Inc., Towson, Md.) in an effort to more rapidly differentiate this group of organisms from other mycobacteria. Bacterial suspensions (0.1 ml) were inoculated by syringe into 7H12 broth containing 2 micrograms of mycobactin P per ml and control broth without mycobactin P. Cultures were incubated at 37 degrees C and read daily with a BACTEC Model 301 (Johnston Laboratories). After 8 days of incubation, the growth index readings for the test broths containing mycobactin P were twice those of the control broths without mycobactin P. Sixty-five isolates of mycobacteria other than M. paratuberculosis were also examined. No difference was noted between the growth index readings of control and mycobactin-containing broths. Except for Mycobacterium avium-Mycobacterium intracellulare, TLC studies differentiated M. paratuberculosis from the other mycobacterial species tested. The GLC data reveal that all M. paratuberculosis isolates had a distinctive peak (14A) which was not found among M. avium-M. intracellulare complex organisms. These data indicate that 7H12 radiometric broth was able to rapidly demonstrate the mycobactin dependence of M. paratuberculosis and GLC and TLC procedures were capable of rapidly differentiating this organism from the other mycobacteria studied. Images PMID:3429629

Damato, J J; Knisley, C; Collins, M T

1987-01-01

47

Numerical analysis of gas-liquid mixed transport process in a multiphase rotodynamic pump  

NASA Astrophysics Data System (ADS)

One of the main challenges in developing multiphase rotodynamic pump is how to avoid gas-liquid separation in high IGVF (inlet gas volume fraction) condition. In this study, the two-fluid model was used to analyse the unsteady gas-liquid two-phase transport process with three-dimensional structure mesh. The turbulence was modelled by SST model and the drag force and added mass force were accounted for in the interfacial momentum transfer terms. The simulation was carried out in five working conditions with different flow rate but same IGVF. The results show that the region of impeller inlet can active the formation of air mass due to the abrupt change of flow passage and the rotation effect of the impeller; in the transport process, the field of gas volume fraction will fluctuate and lead to the fluctuation of the pressure field and the pump head. Also, by comparing the head performance with the experiment, the reliability of the current numerical model and methods in most working conditions is validated.

Yu, Z. Y.; Zhang, Q. Z.; Huang, R.; Cao, S. L.

2012-11-01

48

Effect of cavitation on the properties of coal-tar pitch as studied by gas-liquid chromatography  

SciTech Connect

The applicability of the cavitation-wave effect to coal-tar pitch processing is considered. The results of the GLC analysis of the test material before and after rotor-pulsation cavitation treatment are given. The organic matter of coal-tar pitch was found to degrade upon cavitation; as a result of this, the yields of light and medium fractions considerably increased. 5 refs., 2 figs., 4 tabs.

M.I. Baikenov; T.B. Omarbekov; S.K. Amerkhanova (and others) [Buketov State University, Karaganda (Kazakhstan)

2008-02-15

49

Natural-gas liquids  

Microsoft Academic Search

Casinghead gasoline or natural gasoline, now more suitably known as natural-gas liquids (NGL), was a nuisance when first found, but was developed into a major and profitable commodity. This part of the petroleum industry began at about the turn of the century, and more than 60 yr later the petroleum industry recovers approx. one million bbl of natural-gas liquids a

W. B. Blackstock; G. W. McCullough; R. C. McCutchan

1968-01-01

50

Quantitative isolation and gas-liquid chromatographic analysis of total fecal bile acids  

Microsoft Academic Search

SUMMARY A method for isolation and quantification of fecal bile acids is described which allows sterol balance studies to be made in man or in small laboratory animals without re- quiring the use of radioisotopes in vivo. Bile acids are purified by column and thin-layer chromatography, converted to the trimethylsilyl ethers of their methyl esters, and quantified by GLC with

SCOTT M. GRUNDY; E. H. AHRENS; TATU A. MIETTINEN

51

ANALYSIS OF INTERFACIAL AND MASS TRANSFER EFFECTS ON FORCED CONVECTION IN GAS-LIQUID ANNULAR TWO PHASE FLOW  

Microsoft Academic Search

In a gas-liquid annular two-phase flow one of the main factors influencing the determination of heat transfer rates is the average thickness of the liquid film. A model to accurately represent the heat transfer in such situations has to be able of determining the average liquid film thickness to within a reasonable accuracy. A typical physical aspect in gas-liquid annular

E. Nogueira; B. D. Dantas; R. M. Cotta

2004-01-01

52

Quantitative Analysis of Urine Vapor and Breath by Gas-Liquid Partition Chromatography  

Microsoft Academic Search

When a human being is placed for several days on a completely defined diet, consisting almost entirely of small molecules that are absorbed from the stomach into the blood, intestinal flora disappear because of lack of nutrition. By this technique, the composition of body fluids can be made constant (standard deviation about 10%) after a few days, permitting significant quantitative

Linus Pauling; Arthur B. Robinson; Roy Teranishi; Paul Cary

1971-01-01

53

Gas-liquid chromatographic and gas-liquid-mass spectometric determination of fenvalerate and permethrin residues in grasshoppers and duck tissue samples  

USGS Publications Warehouse

A procedure is described for determining fenvalerate and permethrin residues in grasshoppers and duck tissues. Samples are Soxhlet-extracted with hexane and cleaned up by gel permeation chromatography with an in-line alumina column. Samples are analyzed by gas-liquid chromatography with electron capture detection, and confirmed by gas-liquid chromatography-mass spectrometry. The average recovery from fortified tissues was 97%.

Reichel, W.L.; Kolbe, E.J.; Stafford, C.J.

1981-01-01

54

Plant analysis 2008--planar chromatography.  

PubMed

For 70 years, planar chromatography has been closely connected with the analysis of plants. Also today in its most advanced form "high performance thin-layer chromatography" (HPTLC), the technique plays an important role in identification of medicinal plants and dietary supplements. Detection of adulteration and quantitative determination of marker substances are other widely used applications. The advancement of instrumentation and methodological concepts has created a basis for reliable qualitative and quantitative results in HPTLC. Remarkable progress has been made in the manageability of the entire planar chromatographic process, particularly in the control of chromatogram development and the utilization of images to obtain and compare information about separated samples. Integration of biological detection systems as well as hyphenation to mass spectrometry has widened the applicability of planar chromatography as an analytical technique that is both orthogonal and complementary to HPLC. PMID:19101887

Reich, Eike; Widmer, Valeria

2009-06-01

55

Determination of structure and composition of suberin from the roots of carrot, parsnip, rutabaga, turnip, red beet, and sweet potato by combined gas-liquid chromatography and mass spectrometry.  

PubMed

Suberin from the roots of carrots (Daucus carota), parsnip (Pastinaca sativa), rutabaga (Brassica napobrassica), turnip (Brassica rapa), red beet (Beta vulgaris), and sweet potato (Ipomoea batatas) was isolated by a combination of chemical and enzymatic techniques. Finely powdered suberin was depolymerized with 14% BF(3) in methanol, and soluble monomers (20-50% of suberin) were fractionated into phenolic (<10%) and aliphatic (13-35%) fractions. The aliphatic fractions consisted mainly of omega-hydroxyacids (29-43%), dicarboxylic acids (16-27%), fatty acids (4-18%), and fatty alcohols (3-6%). Each fraction was subjected to combined gas-liquid chromatography and mass spectrometry. Among the fatty acids very long chain acids (>C(20)) were the dominant components in all six plants. In the alcohol fraction C(18), C(20), C(22), and C(24) saturated primary alcohols were the major components. C(16) and C(18) dicarboxylic acids were the major dicarboxylic acids of the suberin of all six plants and in all cases octadec-9-ene-1, 18-dioic acid was the major component except in rutabaga where hexadecane-1, 16-dioic acid was the major dicarboxylic acid. The composition of the omega-hydroxyacid fraction was quite similar to that of the dicarboxylic acids; 18-hydroxy-octadec-9-enoic acid was the major component in all plants except rutabaga, where equal quantities of 16-hydroxyhexadecanoic acid and 18-hydroxyoctadec-9-enoic acid (42% each) were found. Compounds which would be derived from 18-hydroxyoctadec-9-enoic acid and octadec-9-ene-1, 18-dioic acid by epoxidation, and epoxidation followed by hydration of the epoxide, were also detected in most of the suberin samples. The monomer composition of the six plants showed general similarities but quite clear taxonomic differences. PMID:16659124

Kolattukudy, P E; Kronman, K; Poulose, A J

1975-03-01

56

Determination of Structure and Composition of Suberin from the Roots of Carrot, Parsnip, Rutabaga, Turnip, Red Beet, and Sweet Potato by Combined Gas-Liquid Chromatography and Mass Spectrometry 1  

PubMed Central

Suberin from the roots of carrots (Daucus carota), parsnip (Pastinaca sativa), rutabaga (Brassica napobrassica), turnip (Brassica rapa), red beet (Beta vulgaris), and sweet potato (Ipomoea batatas) was isolated by a combination of chemical and enzymatic techniques. Finely powdered suberin was depolymerized with 14% BF3 in methanol, and soluble monomers (20-50% of suberin) were fractionated into phenolic (<10%) and aliphatic (13-35%) fractions. The aliphatic fractions consisted mainly of ?-hydroxyacids (29-43%), dicarboxylic acids (16-27%), fatty acids (4-18%), and fatty alcohols (3-6%). Each fraction was subjected to combined gas-liquid chromatography and mass spectrometry. Among the fatty acids very long chain acids (>C20) were the dominant components in all six plants. In the alcohol fraction C18, C20, C22, and C24 saturated primary alcohols were the major components. C16 and C18 dicarboxylic acids were the major dicarboxylic acids of the suberin of all six plants and in all cases octadec-9-ene-1, 18-dioic acid was the major component except in rutabaga where hexadecane-1, 16-dioic acid was the major dicarboxylic acid. The composition of the ?-hydroxyacid fraction was quite similar to that of the dicarboxylic acids; 18-hydroxy-octadec-9-enoic acid was the major component in all plants except rutabaga, where equal quantities of 16-hydroxyhexadecanoic acid and 18-hydroxyoctadec-9-enoic acid (42% each) were found. Compounds which would be derived from 18-hydroxyoctadec-9-enoic acid and octadec-9-ene-1, 18-dioic acid by epoxidation, and epoxidation followed by hydration of the epoxide, were also detected in most of the suberin samples. The monomer composition of the six plants showed general similarities but quite clear taxonomic differences. PMID:16659124

Kolattukudy, P. E.; Kronman, Karen; Poulose, A. J.

1975-01-01

57

Solid-phase microextraction with capillary gas-liquid chromatography and nitrogen-phosphorus selective detection for the assay of antidepressant drugs in human plasma.  

PubMed

Solid-phase microextraction (SPME) was tested as a sample preparation for the simultaneous assay of ten antidepressant drugs and metabolites (TADs) in human plasma. Aqueous NaOH (0.5 ml, 1 M) and chloramitriptyline (50 microliters, 40 micrograms/ml) as internal standard (I.S.) were added to a 2-ml plasma sample. This mixture was extracted with a 100-micron polydimethylsiloxane SPME fiber (Supelco) for 10 min. After washing in water and methanol (50%) and subsequent drying at room temperature, desorption of the fiber was performed in the injection port of a gas chromatograph at 260 degrees C for 1 min (HP 5890, DB-17 30 m x 0.25 mm I.D., 0.25 micron capillary; 0.7 ml/min nitrogen; nitrogen-phosphorus selective detection). The recovery was found to be very low from plasma (0.3% to 0.8%) but considerably higher from water (about 15%). Therefore, the high protein binding of antidepressants appears to be the main limiting mechanism for a better extraction. However, the analytes were well separated and the calibrations were linear between 125 ng/ml and 2000 ng/ml. The limits of quantification were about 90 ng/ml for imipramine and desipramine, 125 ng/ml for amitriptyline, trimipramine, doxepine, nortriptyline and mianserine and about 200 ng/ml for maprotiline, clomipramine and desmethylclomipramine. The recovery was improved by increasing the extraction time. The influence of the concentrations of the sum of proteins and of alpha-acid glycoprotein on the peak-area ratios ATAD/A I.S. and on absolute peak areas was studied. Peak-area ratios increased with decreasing protein concentration but were found to be independent on alpha-acid glycoprotein. A simple model for the explanation of the effect is presented. Measures for the improvement of sensitivity are discussed. As presented in this paper, which first describes SPME for the analysis of drugs in plasma, SPME with a short extraction time can be of only very limited value for therapeutic drug monitoring. Lower concentrations than the limit of quantification are usually found at therapeutic doses. The method can be useful for toxicological analysis after the accidental or suicidal intake of higher doses. However, an about 10-fold improvement of the sensitivity of the method seems to be possible. PMID:9323542

Ulrich, S; Martens, J

1997-08-29

58

Quantitative gas-liquid chromatography of triglycerides  

Microsoft Academic Search

To determine optimum operating conditions, an extensive study was made of the variables affecting quantitative recovery and\\u000a resolution of model triglyceride mixtures. Parameters investigated included: flash heater temperature, carrier gas flow rate,\\u000a type of carrier gas, column length, glass and metal columns, temperature program rate, linearity of detector response, physical\\u000a design of gas chromatograph, and molecular species of triglyceride.\\u000a \\u000a Results

Carter Litchfield; R. D. Harlow; Raymond Reiser

1965-01-01

59

Analysis of energetic materials by ion chromatography  

Microsoft Academic Search

Ion chromatography is a rapid, sensitive, and selective method for ion analysis in a variety of matrices. Ion chromatography was used to determine levels on chloride and chlorate in potassium perchlorate. Comparisons were made with the specific ion electrons method presently being used for these analyses. Also to be discussed are ion chromatographic methods for determining ammonium in boron potassium

Hershey

1985-01-01

60

STUDIES ON THE IDENTIFICATION OF HARMFUL RADIOLYTIC PRODUCTS OF 30% TBP-N-DODECANE-HNO3 BY GAS-LIQUID CHROMATOGRAPHY. II. FORMATION AND CHARACTERIZATION OF HIGH MOLECULAR WEIGHT ORGANOPHOSPHATES  

Microsoft Academic Search

Gamma radiolysis of Purex solvent, 30% tri-n-butylphosphate-n-dodecane-HNO3 is observed to yield many undesirable metal complexing species. A method for identifying the gas-liquid chromatographic (GLC) signatures of high molecular weight organophosphates (HMPs) through a nitrogen- and phosphorous-selective detector is described. Fractionation of the radiolyzed solvent by vacuum distillation resulted in the enrichment of HMP species in the high boiling, viscous residue

S. C. Tripathi; A. Ramanujam; K. K. Gupta; P. Bindu

2001-01-01

61

Analysis of energetic materials by ion chromatography  

SciTech Connect

Ion chromatography is a rapid, sensitive, and selective method for ion analysis in a variety of matrices. Ion chromatography was used to determine levels on chloride and chlorate in potassium perchlorate. Comparisons were made with the specific ion electrons method presently being used for these analyses. Also to be discussed are ion chromatographic methods for determining ammonium in boron potassium nitrate, and chloride and ammonium in CP.

Hershey, M.K.

1985-01-01

62

Supersonic Gas-Liquid Cleaning System  

NASA Technical Reports Server (NTRS)

The Supersonic Gas-Liquid Cleaning System Research Project consisted mainly of a feasibility study, including theoretical and engineering analysis, of a proof-of-concept prototype of this particular cleaning system developed by NASA-KSC. The cleaning system utilizes gas-liquid supersonic nozzles to generate high impingement velocities at the surface of the device to be cleaned. The cleaning fluid being accelerated to these high velocities may consist of any solvent or liquid, including water. Compressed air or any inert gas is used to provide the conveying medium for the liquid, as well as substantially reduce the total amount of liquid needed to perform adequate surface cleaning and cleanliness verification. This type of aqueous cleaning system is considered to be an excellent way of conducting cleaning and cleanliness verification operations as replacements for the use of CFC 113 which must be discontinued by 1995. To utilize this particular cleaning system in various cleaning applications for both the Space Program and the commercial market, it is essential that the cleaning system, especially the supersonic nozzle, be characterized for such applications. This characterization consisted of performing theoretical and engineering analysis, identifying desirable modifications/extensions to the basic concept, evaluating effects of variations in operating parameters, and optimizing hardware design for specific applications.

Kinney, Frank

1996-01-01

63

Validation of a chromatography data analysis software  

Microsoft Academic Search

The performance of chromatography data analysis software packages is of cardinal importance when the precision and the accuracy of a chromatographic system are evaluated. Users cannot rely on a procedure generating chromatographic data of known accuracy. Holistic approaches cannot always be entirely trusted. We propose a new method consisting in validating a data analysis package against computer generated chromatograms of

Attila Felinger; Georges Guiochon

2001-01-01

64

APPLICATION OF GAS CHROMATOGRAPHY IN FOOD ANALYSIS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Gas chromatography (GC) is used widely in applications involving food analysis. Typical applications pertain to the quantitative and/or qualitative analysis of food composition, natural products, food additives, flavor and aroma components, a variety of transformation products, and contaminants suc...

65

Microfluidic study of fast gas-liquid reactions.  

PubMed

We present a new concept for studies of the kinetics of fast gas-liquid reactions. The strategy relies on the microfluidic generation of highly monodisperse gas bubbles in the liquid reaction medium and subsequent analysis of time-dependent changes in bubble dimensions. Using reactions of CO(2) with secondary amines as an exemplary system, we demonstrate that the method enables rapid determination of reaction rate constant and conversion, and comparison of various binding agents. The proposed approach addresses two challenges in studies of gas-liquid reactions: a mass-transfer limitation and a poorly defined gas-liquid interface. The proposed strategy offers new possibilities in studies of the fundamental aspects of rapid multiphase reactions, and can be combined with throughput optimization of reaction conditions. PMID:22176612

Li, Wei; Liu, Kun; Simms, Ryan; Greener, Jesse; Jagadeesan, Dinesh; Pinto, Sascha; Günther, Axel; Kumacheva, Eugenia

2012-02-15

66

Christhin: Quantitative Analysis of Thin Layer Chromatography  

E-print Network

Manual for Christhin 0.1.36 Christhin (Chromatography Riser Thin) is software developed for the quantitative analysis of data obtained from thin-layer chromatographic techniques (TLC). Once installed on your computer, the program is very easy to use, and provides data quickly and accurately. This manual describes the program, and reading should be enough to use it properly.

Barchiesi, Maximiliano; Renaudo, Carlos; Rossi, Pablo; Pramparo, María de Carmen; Nepote, Valeria; Grosso, Nelson Ruben; Gayol, María Fernanda

2012-01-01

67

Analysis of complex lipid mixtures by thin-layer chromatography and complementary methods  

Microsoft Academic Search

Conclusion  Further work has been done on the application of thin-layer adsorption chromatography to the fractionation of complex lipid\\u000a mixtures into classes.\\u000a \\u000a New methods, the use of siliconized silicic acid plates and the application of thin-layer adsorption chromatography combined\\u000a with the complementary techniques of gas-liquid chromatography and paper chromatography, are presented for the resolution\\u000a of classes of lipids into their constituents.

Donald C. Malins; Helmut K. Mangold

1960-01-01

68

Chromatography.  

ERIC Educational Resources Information Center

This booklet presents some activities on chromatography. Directions for preparing leaf pigment extracts using alcohol are given, and paper chromatography and thin-layer chromatography are described as modifications of the basic principles of chromatography. (KHR)

Brantley, L. Reed, Sr.; Demanche, Edna L.; Klemm, E. Barbara; Kyselka, Will; Phillips, Edwin A.; Pottenger, Francis M.; Yamamoto, Karen N.; Young, Donald B.

69

Advances in gas-liquid flows 1990  

Microsoft Academic Search

Gas-liquid two-phase flows commonly occur in nature and industrial applications. Rain, clouds, geysers, and waterfalls are examples of natural gas-liquid flow phenomena, whereas industrial applications can be found in nuclear reactors, steam generators, boilers, condensers, evaporators, fuel atomization, heat pipes, electronic equipment cooling, petroleum engineering, chemical process engineering, and many others. The household-variety phenomena such as garden sprinklers, shower, whirlpool

J. M. Kim; A. Hashemi

1990-01-01

70

AN ANALYSIS OF FRONT TRACKING FOR CHROMATOGRAPHY BURTON WENDROFF \\Lambda  

E-print Network

AN ANALYSIS OF FRONT TRACKING FOR CHROMATOGRAPHY BURTON WENDROFF \\Lambda Abstract. We prove that front tracking has a convergent subsequence for the equations of chromatography for initial data. An example of a computation with the latter is presented. Key Words. Chromatography, hyperbolic, front

71

Ion Chromatography Analysis of Dibutyl Phosphoric Acid  

SciTech Connect

Analysis of dibutyl phosphate (DBP), a degradation product of tributyl phosphate (TBP), has long been a problem analysis by Ion Chromatography at the Savannah River Site. Due to the presence of UO{sub 2}{sup +2} and high NO{sub 3}{sup {minus}1} concentrations, inadequate recovery and separation of DBP on the chromatographic column had rendered the analysis undependable and very inconsistent, thus causing high uncertainties in the data. The method presented here by the Savannah River Technology Center (SRTC)/Analytical Development Section (ADS) addresses the sample preparation problems encountered when analyzing for DBP in the presence of uranium and nitrate. The data presented reflects the improvements made to decrease data uncertainty and increase data accuracy and precision.

Ray, R.J.

1998-12-04

72

Unification of stagewise control of production of vitamin C using highly efficient liquid chromatography  

Microsoft Academic Search

The previously developed methods for the analysis of certain intermediate products in the synthesis of ascorbic acid (AA) using gas-liquid chromatography (GLC) and thin-layer chromatography (TLC) have substantial drawbacks. Several analytical procedures using TLC [2~ 11-13] involve considerable difficulties with respect to quantitative evaluation of the chromatograms. Analysis by the GLC method requires preliminary isolation of the products from the

Yu. A. Lelikov; G. G. Vasiyarov; E. M. Syanava; V. M. Svetlaeva; M. Ts. Yanotovskii

1988-01-01

73

T-junction separation modelling in gas–liquid two-phase flow  

Microsoft Academic Search

The principle of dynamic separation with T-junction having a horizontal run and a vertical branch is presented. The analysis of gas–liquid flow systems involving T-junctions is very important for applications to phase separation in gas–liquid transport pipelines, but the complexity of the multi dimensional phenomenon of dividing two-phase flow in T-junction needs special modelling. Based on the fundamental mass, momentum

Dionissios P. Margaris

2007-01-01

74

Human Plasma Proteome Analysis by Multidimensional Chromatography Prefractionation and Linear Ion Trap Mass  

E-print Network

Human Plasma Proteome Analysis by Multidimensional Chromatography Prefractionation and Linear Ion chromatography has attracted extensive attention, but most published works have focused on the fractionation strong cation exchange chromatography and reversed-phase chromatography. The resulting 30 samples were

Tian, Weidong

75

Chromatography  

NSDL National Science Digital Library

This site provides fundamental background information about chromatography, including plate theory, rate theory, the mechanisms of separations, and qualitative and quantitative aspects of chromatography. The format is a series of PowerPoint-like presentations available in PDF format.

Hardy, James K.

76

Chromatography  

MedlinePLUS

... high pressure liquid, or ion exchange chromatography. In general, chromatography takes advantage of the differences in the chemicals you want to separate, such as their size, electric charge, or ability to stick to (bind) to ...

77

High Performance Gas-Liquid Reaction Technology  

Microsoft Academic Search

High performance of reactors is often related to high throughput or high product quality. Scale- up ability, flexibility in operating parameters, product equivalence and new reactor concepts are other factors to be considered. Mass transfer in loop reactors is discussed and compared with other gas\\/liquid contacting systems. Guidelines for reactor selection are given. In the chemical and food industry the

Rene F. Duveen

78

Method for recovery of natural gas liquids  

Microsoft Academic Search

This patent describes a method for recovering natural gas liquids from a fuel gas stream with high hydrogen and carbon dioxide content comprising the steps of: dehydrating the fuel gas stream; compressing the fuel gas stream to a pressure of generally 300 psi; chilling the fuel gas stream in an inlet gas cooler to generally - 45°F; separating the chilled,

G. J. IV Montgomery; H. K. Aghili

1987-01-01

79

Chromatography  

NSDL National Science Digital Library

This lab activity from the Biotechnology Alliance for Suncoast Biology Educators covers background information on the basic types of chromatography and has the student separate pigments extracted from pens and plant leaves using paper chromatography. The lesson includes the materials needed and the demonstration procedures.

Keirle, Matt

80

Minimizing liquid contaminants in natural gas liquids  

SciTech Connect

In processing natural gas liquids, significant contamination occurs with liquid dispersions and emulsions. Natural gas liquids (NGL) and liquid petroleum gas (LPG) streams are treated with caustic to remove residual organic sulfur compounds such as mercaptans and with amines to remove hydrogen sulfide. In both cases a liquid/liquid contactor is used. Significant amounts of the caustic or amine can be carried over into the product stream in process units that are running at rates above design capacity, are treating high sulfur feed stocks, or have other operational problems. The carried over liquid results in off-spec products, excessive loses of caustic or amine, and can cause operating problems in downstream processes. In addition, water is a significant contaminant which can cause LPG and natural gasoline to be off-specification. This paper discusses a new technique for separating very stable liquid dispersions of caustic, amine, or water from natural gas liquids using liquid/liquid cartridge coalescers constructed with specially formulated polymer and fluoropolymer medium with enhanced surface properties. In addition, factors influencing the coalescer mechanism will be discussed including interfacial tension, concentration of surface active compounds, steric repulsion, and electrostatic charge affects. Results from field tests, operating data from commercial installations, and economic benefits will also be presented.

Brown, R.L. [Pall Industrial Process Filtration, East Hills, NY (United States); Wines, T.H. [Pall Scientific and Laboratory Services, Port Washington, NY (United States); Williamson, K.M. [Pall Process Equipment Development, Cortland, NY (United States)

1996-12-31

81

ANALYSIS OF TECHNICAL CHLORDANE BY GAS CHROMATOGRAPHY MASS SPECTROMETRY  

EPA Science Inventory

The composition of technical chlordane has been investigated by combined gas chromatography/mass spectrometry, employing a column commonly used for pesticide residue analysis. Partial or complete structure identification have been assigned to some 45 individual constituents. Many...

82

Chromatography  

NSDL National Science Digital Library

In this activity, explore chromatography and the various colors that make up the ink in markers. Use this activity to investigate cohesion and adhesion. The online version of this activity is set up so that learners solve a mystery.

2014-04-25

83

Chromatography  

NSDL National Science Digital Library

The North Carolina Community College System BioNetwork's interactive eLearning tools (IETs) are reusable chunks of training that can be deployed in a variety of courses or training programs. IETs are designed to enhance, not replace hands-on training. Learners are able to enter a hands-on lab experience better prepared and more confident. This particular IET delves into chromatography including the basics, the three types (affinity, ion exchange, size exclusion), and the parts and functions associated with chromatography.

84

Chromatography  

NSDL National Science Digital Library

In this activity, by the Concord Consortium's Molecular Literacy project, students "learn about the phases of molecular separation, and then experiment with paper and ion chromatography." The activity itself is a java-based interactive resource built upon the free, open source Molecular Workbench software. In addition, visitors will find an overview of the activity, assessments, and concepts and their correlation to AAAS and NSES standards.

85

Chromatography  

NSDL National Science Digital Library

In this chemistry activity, learners will separate a mixture of FD&C dyes (colors certified and allowed by the US for the Food, Pharmaceutical, Cosmetics & Personal Care industry) to practice chromatography, a separation technique for mixtures. Learners will record their observations on a data table and note trends. This resource includes questions for learners and instructions for preparing the colors from M&Ms, Orange Kool-Aid, and food coloring.

The Science House

2014-01-28

86

Determination of Drop Sizes in Annular Gas\\/Liquid Flows in Vertical and Horizontal Pipes  

Microsoft Academic Search

Measurement of drop sizes play vital role in applications dealing with gas\\/liquid flow mixtures. In the present work, drop sizes in vertical and horizontal pipe flows were determined using Malvern 2600HSD system that applies laser diffraction method. From the analysis of the experimental data obtained at two different pipe orientations, two separate expressions were developed to determine Sauter mean diameter,

A. Sarimeseli

2009-01-01

87

Separation and IR Analysis of a Mixture of Organic Compounds.  

ERIC Educational Resources Information Center

Presents an experiment which includes fractional distillation with gas-liquid chromatography (GLC) and infrared analysis. Objectives are to introduce students to fractional distillation and analysis of each fraction by GLC, to induce them to decide if each fraction is sufficient for infrared analysis, and to identify unknowns. (Author/JN)

Thompson, Evan M.; Almy, John

1982-01-01

88

Analysis of protein composition using multidimensional chromatography and mass spectrometry.  

PubMed

Multidimensional liquid chromatography of peptides produced by protease digestion of complex protein mixtures followed by tandem mass spectrometry can be coupled with automated database searching to identify large numbers of proteins in complex samples. These methods avoid the limitations of gel electrophoresis and in-gel digestions by directly identifying protein mixtures in solution. One method used extensively is named Multidimensional Protein Identification Technology (MudPIT), where reversed-phase chromatography and strong cation-exchange chromatography are coupled directly in a microcapillary column. This column is then placed in line between an HPLC and a mass spectrometer for complex mixture analysis. MudPIT remains a powerful approach for analyzing complex mixtures like whole proteomes and protein complexes. MudPIT is used for quantitative proteomic analysis of complex mixtures to generate novel biological insights. © 2014 by John Wiley & Sons, Inc. PMID:25367006

Link, Andrew J; Washburn, Michael P

2014-01-01

89

Automation of pesticide residue analysis  

Microsoft Academic Search

The routine analysis of pesticide residue levels in biological tissue by gas-liquid chromatography is greatly facilitated by the use of computers to reduce computation time. Modern systems can be readily adapted to small computers. The nature of gas chromatographic signals permits the insertion of digitizers between the gas chromatograph and the computer. The resulting system permits completely automatic retrieval of

R. W. Jennings; D. L. Jue; J. E. Suggs

1970-01-01

90

Thin-layer chromatography analysis of fructooligosaccharides in biological samples  

Microsoft Academic Search

This study presents the application of a rapid, simple and inexpensive thin-layer chromatography (TLC) for the analysis of fructooligosaccharides (FOSs) as feed additives (prebiotics) in complicated biological samples with minimal pre-treatment. Prebiotics have been monitored in different parts of the intestinal tract (jejunum, ileum and colon) of monogastric animals to which commercially available dietetic products containing fructooligosaccharides Raftifeed IPX, Raftilose

Katarína Reiffová; Radomíra Nemcová

2006-01-01

91

CHEMICAL ANALYSIS OF WET SCRUBBERS UTILIZING ION CHROMATOGRAPHY  

EPA Science Inventory

The report describes the key elements required to develop a sampling and analysis program for a wet scrubber using ion chromatography as the main analytical technique. The first part of the report describes a sampling program for two different types of wet scrubbers: the venturi/...

92

Using Single Drop Microextraction for Headspace Analysis with Gas Chromatography  

ERIC Educational Resources Information Center

Headspace (HS) gas chromatography (GC) is commonly used to analyze samples that contain non-volatiles. In 1996, a new sampling technique called single drop microextraction, SDME, was introduced, and in 2001 it was applied to HS analysis. It is a simple technique that uses equipment normally found in the undergraduate laboratory, making it ideal…

Riccio, Daniel; Wood, Derrick C.; Miller, James M.

2008-01-01

93

EXPERTIMENT 10 GAS CHROMATOGRAPHY QUANTITATIVE ANALYSIS USING CAPILLARY  

E-print Network

EXPERTIMENT 10 GAS CHROMATOGRAPHY QUANTITATIVE ANALYSIS USING CAPILLARY COLUMNS The purpose gas chromatograph using capillary column and splitting injection mode. See also the HP 5890 gas A mixture of hydrocarbons (xylenes) will be provided to run on the gas chromatograph so that the retention

Nazarenko, Alexander

94

EXPERIMENT 9 GAS CHROMATOGRAPHY QUALITATIVE ANALYSIS USING PACKED  

E-print Network

EXPERIMENT 9 GAS CHROMATOGRAPHY QUALITATIVE ANALYSIS USING PACKED COLUMN The purpose become familiar with the use of a temperature programmable gas chromatograph. See also the gas on the gas chromatograph so that the tr values may be obtained. Instrument Start Up. Turn on the gas

Nazarenko, Alexander

95

Fast gas chromatography for pesticide residues analysis  

Microsoft Academic Search

The importance of method development in the area of pesticide residues analysis is apparent from legislative requirements continuously decreasing the maximum acceptable concentration levels in food and water. This covers also contribution in the science in the field of ultra-trace analysis of organic pollutants in complex mixtures. Analysis time is one of the most important aspects that should be considered

Milena Dömötörová; Eva Matisová

2008-01-01

96

Gas-liquid separator and method of operation  

DOEpatents

A system for gas-liquid separation in electrolysis processes is provided. The system includes a first compartment having a liquid carrier including a first gas therein and a second compartment having the liquid carrier including a second gas therein. The system also includes a gas-liquid separator fluidically coupled to the first and second compartments for separating the liquid carrier from the first and second gases.

Soloveichik, Grigorii Lev (Latham, NY); Whitt, David Brandon (Albany, NY)

2009-07-14

97

Lipid analysis by quantitative thin-layer chromatography  

Microsoft Academic Search

Techniques for the quantitative analysis of lipids using thin-layer chromatography (TLC) are reviewed. The general procedures\\u000a are divided into two groups on the basis of whether or not the methods involve the recovery of substances from chromatoplates.\\u000a \\u000a Recovery methods are elaborated under detection of spots, recovery of substances and quantification. Methods are described\\u000a for the recovery of labile compounds from

O. S. Privett; M. L. Blank; D. W. Codding; E. C. Nickell

1965-01-01

98

Quantitative analysis of lipids by thin-layer chromatography  

Microsoft Academic Search

A procedure is described for the quantitative analysis of neutral and phospholipids by thinlayer chromatography (TLC) employing\\u000a densitometry. The chromatophates are prepared with the usual solvent systems. The spots are charred under standard conditions\\u000a and analyzed with a Photovolt Corp. densitometer equipped with a special stage designed for holding 20×20 cm chromatoplates.\\u000a Each spot on the chromatoplate gives a peak

M. L. Blank; J. A. Schmit; O. S. Privett

1964-01-01

99

Isotope-ratio-monitoring gas chromatography methods for high-precision isotopic analysis of nanomole  

E-print Network

Isotope-ratio-monitoring gas chromatography methods for high-precision isotopic analysis and a commercially available continuous-flow, gas chromatography interface (the Finnigan Gas Bench II). This work

Bebout, Gray E.

100

Rising and descending bubble size distributions in gas–liquid and gas–liquid–solid slurry bubble column reactor  

Microsoft Academic Search

Dual-tip conductivity probe is used to determine distributions of rising and descending bubble size in gas–liquid and gas–liquid–solid bubble column. The column is 100mm in internal diameter and 1500mm in height. The solid particles used are glass beads with average diameter of 17.82?m representing typical particle size for catalytic slurry reactors. Bubbles are categorized to two size classes, small bubbles

Li-juan Zhang; Tao Li; Wei-yong Ying; Ding-ye Fang

2008-01-01

101

Principles of Micellar Electrokinetic Capillary Chromatography Applied in Pharmaceutical Analysis  

PubMed Central

Since its introduction capillary electrophoresis has shown great potential in areas where electrophoretic techniques have rarely been used before, including here the analysis of pharmaceutical substances. The large majority of pharmaceutical substances are neutral from electrophoretic point of view, consequently separations by the classic capillary zone electrophoresis; where separation is based on the differences between the own electrophoretic mobilities of the analytes; are hard to achieve. Micellar electrokinetic capillary chromatography, a hybrid method that combines chromatographic and electrophoretic separation principles, extends the applicability of capillary electrophoretic methods to neutral analytes. In micellar electrokinetic capillary chromatography, surfactants are added to the buffer solution in concentration above their critical micellar concentrations, consequently micelles are formed; micelles that undergo electrophoretic migration like any other charged particle. The separation is based on the differential partitioning of an analyte between the two-phase system: the mobile aqueous phase and micellar pseudostationary phase. The present paper aims to summarize the basic aspects regarding separation principles and practical applications of micellar electrokinetic capillary chromatography, with particular attention to those relevant in pharmaceutical analysis. PMID:24312804

Hancu, Gabriel; Simon, Brigitta; Rusu, Aura; Mircia, Eleonora; Gyéresi, Árpád

2013-01-01

102

Size-exclusion chromatography system for macromolecular interaction analysis  

DOEpatents

A low pressure, microcomputer controlled system employing high performance liquid chromatography (HPLC) allows for precise analysis of the interaction of two reversibly associating macromolecules such as proteins. Since a macromolecular complex migrates faster than its components during size-exclusion chromatography, the difference between the elution profile of a mixture of two macromolecules and the summation of the elution profiles of the two components provides a quantifiable indication of the degree of molecular interaction. This delta profile is used to qualitatively reveal the presence or absence of significant interaction or to rank the relative degree of interaction in comparing samples and, in combination with a computer simulation, is further used to quantify the magnitude of the interaction in an arrangement wherein a microcomputer is coupled to analytical instrumentation in a novel manner.

Stevens, Fred J. (Downers Grove, IL)

1988-01-01

103

Simultaneous analysis for water- and fat-soluble vitamins by a novel single chromatography technique unifying supercritical fluid chromatography and liquid chromatography.  

PubMed

Chromatography techniques usually use a single state in the mobile phase, such as liquid, gas, or supercritical fluid. Chromatographers manage one of these techniques for their purpose but are sometimes required to use multiple methods, or even worse, multiple techniques when the target compounds have a wide range of chemical properties. To overcome this challenge, we developed a single method covering a diverse compound range by means of a "unified" chromatography which completely bridges supercritical fluid chromatography and liquid chromatography. In our method, the phase state was continuously changed in the following order; supercritical, subcritical and liquid. Moreover, the gradient of the mobile phase starting at almost 100% CO2 was replaced with 100% methanol at the end completely. As a result, this approach achieved further extension of the polarity range of the mobile phase in a single run, and successfully enabled the simultaneous analysis of fat- and water-soluble vitamins with a wide logP range of -2.11 to 10.12. Furthermore, the 17 vitamins were exceptionally separated in 4min. Our results indicated that the use of dense CO2 and the replacement of CO2 by methanol are practical approaches in unified chromatography covering diverse compounds. Additionally, this is a first report to apply the novel approach to unified chromatography, and can open another door for diverse compound analysis in a single chromatographic technique with single injection, single column and single system. PMID:25200530

Taguchi, Kaori; Fukusaki, Eiichiro; Bamba, Takeshi

2014-10-01

104

Acoustic probe for solid-gas-liquid suspensions. 1998 annual progress report  

SciTech Connect

'The proposed research will develop an acoustic probe for monitoring particle size and volume fraction in slurries in the absence and presence of gas. The goals are to commission and verify the probe components and system operation, develop theory for the forward and inverse problems for acoustic wave propagation through a three phase medium, and experimentally verify the theoretical analysis. The acoustic probe will permit measurement of solid content in gas-liquid-solid waste slurries in tanks across the DOE complex.'

Tavlarides, L.L.; Sangani, A.S. [Syracuse Univ., NY (US); Greenwood, M.S. [Pacific Northwest National Lab., Richland, WA (US)

1998-06-01

105

Differential Protein Expression Analysis via Liquid-Chromatography/Mass-Spectrometry Data Visualization  

E-print Network

Differential Protein Expression Analysis via Liquid-Chromatography/Mass-Spectrometry Data, Germany (a) (b) Figure 1: Interactive visualization of liquid-chromatography/mass-spectrometry data: (a of liquid-chromatography/mass-spectrometry data in a 3D space, which allows for the understanding

Linsen, Lars

106

Targeted analysis of glycomics liquid chromatography/mass spectrometry data.  

PubMed

Hydrophilic interaction chromatography (HILIC) liquid chromatography/mass spectrometry (LC/MS) is appropriate for all native and reductively aminated glycan classes. HILIC carries the advantage that retention times vary predictably according to oligosaccharide composition. Chromatographic conditions are compatible with sensitive and reproducible glycomics analysis of large numbers of samples. The data are extremely useful for quantitative profiling of glycans expressed in biological tissues. With these analytical developments, the rate-limiting factor for widespread use of HILIC LC/MS in glycomics is the analysis of the data. In order to eliminate this problem, a Java-based open source software tool, Manatee, was developed for targeted analysis of HILIC LC/MS glycan datasets. This tool uses user-defined lists of compositions that specify the glycan chemical space in a given biological context. The program accepts high-resolution LC/MS data using the public mzXML format and is capable of processing a large data file in a few minutes on a standard desktop computer. The program allows mining of HILIC LC/MS data with an output compatible with multivariate statistical analysis. It is envisaged that the Manatee tool will complement more computationally intensive LC/MS processing tools based on deconvolution and deisotoping of LC/MS data. The capabilities of the tool were demonstrated using a set of HILIC LC/MS data on organ-specific heparan sulfates. PMID:20953780

Dreyfuss, Jonathan M; Jacobs, Christopher; Gindin, Yevgeniy; Benson, Gary; Staples, Gregory O; Zaia, Joseph

2011-01-01

107

DEVELOPMENT AND VALIDATION OF A MULTIFIELD MODEL OF CHURN-TURBULENT GAS/LIQUID FLOWS  

SciTech Connect

The accuracy of numerical predictions for gas/liquid two-phase flows using Computational Multiphase Fluid Dynamics (CMFD) methods strongly depends on the formulation of models governing the interaction between the continuous liquid field and bubbles of different sizes. The purpose of this paper is to develop, test and validate a multifield model of adiabatic gas/liquid flows at intermediate gas concentrations (e.g., churn-turbulent flow regime), in which multiple-size bubbles are divided into a specified number of groups, each representing a prescribed range of sizes. The proposed modeling concept uses transport equations for the continuous liquid field and for each bubble field. The overall model has been implemented in the NPHASE-CMFD computer code. The results of NPHASE-CMFD simulations have been validated against the experimental data from the TOPFLOW test facility. Also, a parametric analysis on the effect of various modeling assumptions has been performed.

Elena A. Tselishcheva; Steven P. Antal; Michael Z. Podowski; Donna Post Guillen

2009-07-01

108

Analysis of olive and hazelnut oil mixtures by high-performance liquid chromatography–atmospheric pressure chemical ionisation mass spectrometry of triacylglycerols and gas–liquid chromatography of non-saponifiable compounds (tocopherols and sterols)  

Microsoft Academic Search

We analysed the triacylglycerol, tocopherol and sterol composition of hazelnut oil, olive oil and their mixtures (90% olive oil with 10% hazelnut oil, 70% olive with 30% hazelnut oil and 50% olive oil with 50% hazelnut oil). The main triacylglycerols were 1,2,3-trioleylglycerol, 2,3-dioleyl-1-palmitoylglycerol, 2,3-dioleyl-1-linoleylglycerol and 2,3-dioleyl-1-stearoylglycerol. Non-saponfiable compounds (tocopherols and sterols) were derivatised as O-trimethylsilyl ethers. ?-Tocopherol was the main

Javier Parcerisa; Isidre Casals; J. Boatella; R. Codony; M. Rafecas

2000-01-01

109

Injector design guidelines for gas/liquid propellant systems  

NASA Technical Reports Server (NTRS)

Injector design guidelines are provided for gas/liquid propellant systems. Information was obtained from a 30-month applied research program encompassing an analytical, design, and experimental effort to relate injector design parameters to simultaneous attainment of high performance and component (injector/thrust chamber) compatibility for gas/liquid space storable propellants. The gas/liquid propellant combination studied was FLOX (82.6% F2)/ ambient temperature gaseous methane. Design criteria that provide for simultaneous attainment of high performance and chamber compatibility are presented for both injector types. Parametric data are presented that are applicable for the design of circular coaxial and like-doublet injectors that operate with design parameters similar to those employed. However, caution should be exercised when applying these data to propellant combinations whose elements operate in ranges considerably different from those employed in this study.

Falk, A. Y.; Burick, R. J.

1973-01-01

110

Investigation on a gas-liquid ejector using three-dimensional CFD model  

NASA Astrophysics Data System (ADS)

This paper is focusing on the numeral study of a gas-liquid ejector used for ballast water treatment. The gasliquid ejector is investigated through steady three-dimensional multiphase CFD analysis with commercial software ANSYS-CFX 13.0. Water as the primary fluid is driven through the driving nozzle and air is ejected into as the second gas instead of the ozone in real application. Several turbulence models such as Standard k-? model, RNG k-? model, SST model and k-? model, and different mesh size and compared extensively with the experimental results to eliminate the influence of the auxiliary system, turbulence models and mesh generation. The appropriate numerical model in terms of the best combination of turbulence model and mesh size are used in the subsequent research the study the influence of the operating condition such as the driving pressure/velocity and the back pressure of the ejector on its performance. The results provide deep insight on the influence of various factors on the performance of gas-liquid ejector. And the proposed numerical model will be very helpful in the further design optimization of the gas-liquid ejectors.

Kang, S. H.; Song, X. G.; Park, Y. C.

2012-11-01

111

Stereospecific analysis of fish oil triacyl- sn -glycerols  

Microsoft Academic Search

Stereospecific analysis of fish oil triacyl-sn-glycerols was carried out by novel high-performance liquid chromatography on a chiral stationary phase. The positional distributions\\u000a of fatty acids were determined without accumulation of errors in a particular position and preferential hydrolysis for a particular\\u000a fatty acid. High-resolution gas-liquid chromatography on an open tubular column detailed the distribution of unsaturated fatty\\u000a acid isomers having

Yasuhiro Ando; Kazuhiko Nishimura; Naoki Aoyanagi; Toru Takagi

1992-01-01

112

Modified electrokinetic sample injection method in chromatography and electrophoresis analysis  

DOEpatents

A sample injection method for horizontal configured multiple chromatography or electrophoresis units, each containing a number of separation/analysis channels, that enables efficient introduction of analyte samples. This method for loading when taken in conjunction with horizontal microchannels allows much reduced sample volumes and a means of sample stacking to greatly reduce the concentration of the sample. This reduction in the amount of sample can lead to great cost savings in sample preparation, particularly in massively parallel applications such as DNA sequencing. The essence of this method is in preparation of the input of the separation channel, the physical sample introduction, and subsequent removal of excess material. By this method, sample volumes of 100 nanoliter to 2 microliters have been used successfully, compared to the typical 5 microliters of sample required by the prior separation/analysis method.

Davidson, J. Courtney (Livermore, CA); Balch, Joseph W. (Livermore, CA)

2001-01-01

113

Prediction of gas-liquid two-phase flow regime in microgravity  

NASA Technical Reports Server (NTRS)

An attempt is made to predict gas-liquid two-phase flow regime in a pipe in a microgravity environment through scaling analysis based on dominant physical mechanisms. Simple inlet geometry is adopted in the analysis to see the effect of inlet configuration on flow regime transitions. Comparison of the prediction with the existing experimental data shows good agreement, though more work is required to better define some physical parameters. The analysis clarifies much of the physics involved in this problem and can be applied to other configurations.

Lee, Jinho; Platt, Jonathan A.

1993-01-01

114

Permanent gas analysis using gas chromatography with vacuum ultraviolet detection.  

PubMed

The analysis of complex mixtures of permanent gases consisting of low molecular weight hydrocarbons, inert gases, and toxic species plays an increasingly important role in today's economy. A new gas chromatography detector based on vacuum ultraviolet (VUV) spectroscopy (GC-VUV), which simultaneously collects full scan (115-240nm) VUV and UV absorption of eluting analytes, was applied to analyze mixtures of permanent gases. Sample mixtures ranged from off-gassing of decomposing Li-ion and Li-metal batteries to natural gas samples and water samples taken from private wells in close proximity to unconventional natural gas extraction. Gas chromatography separations were performed with a porous layer open tubular column. Components such as C1-C5 linear and branched hydrocarbons, water, oxygen, and nitrogen were separated and detected in natural gas and the headspace of natural gas-contaminated water samples. Of interest for the transport of lithium batteries were the detection of flammable and toxic gases, such as methane, ethylene, chloromethane, dimethyl ether, 1,3-butadiene, CS2, and methylproprionate, among others. Featured is the capability for deconvolution of co-eluting signals from different analytes. PMID:25724098

Bai, Ling; Smuts, Jonathan; Walsh, Phillip; Fan, Hui; Hildenbrand, Zacariah; Wong, Derek; Wetz, David; Schug, Kevin A

2015-04-01

115

Simulation of gas-liquid flow in slug catchers  

SciTech Connect

For the optimization of existing slug catchers of the multiple-pipe type and the development of novel configurations small-scale model tests are used employing a two-liquid system with a density ratio representative of that of the gas/liquid phases in practice. The technique has been validated by field tests with an existing slug catcher.

Bos, A.; du Chatinier, J.G.

1985-03-01

116

Simulation of gas/liquid flow in slug catchers  

SciTech Connect

For the optimization of existing multiple-pipe-type slug catchers and the development of novel configurations, small-scale model tests are used that use a two-liquid system with a density ratio representative of that of the gas/liquid phases in practice. The technique has been validated by field tests with an existing slug catcher.

Bos, A.; Du Chatinier, J.G.

1987-08-01

117

Simulation of gas-liquid flow in slug catchers  

Microsoft Academic Search

For the optimization of existing slug catchers of the multiple-pipe type and the development of novel configurations small-scale model tests are used employing a two-liquid system with a density ratio representative of that of the gas\\/liquid phases in practice. The technique has been validated by field tests with an existing slug catcher.

A. Bos; J. G. du Chatinier

1985-01-01

118

Simulation of gas\\/liquid flow in slug catchers  

Microsoft Academic Search

For the optimization of existing multiple-pipe-type slug catchers and the development of novel configurations, small-scale model tests are used that use a two-liquid system with a density ratio representative of that of the gas\\/liquid phases in practice. The technique has been validated by field tests with an existing slug catcher.

A. Bos; J. G. Du Chatinier

1987-01-01

119

GAS–LIQUID REACTION KINETICS: A REVIEW OF DETERMINATION METHODS  

Microsoft Academic Search

The aim of this article is to provide comprehensive insight into the determination and interpretation of reaction kinetics of two-phase (gas–liquid) systems. Various aspects of the methodologies used for the measurements of kinetic parameters (such as equipment design, corresponding theoretical background, main steps, advantages, and limitations) are discussed in detail. In addition, an illustrating example is provided based on an

Prakash D. Vaidya; Eugeny Y. Kenig

2007-01-01

120

A Lab Experiment to Introduce Gas/Liquid Solubility  

ERIC Educational Resources Information Center

A simplified version of a volumetric apparatus for gas/liquid solubility measurements is proposed. The procedure familiarizes undergraduate students with the experimental study of the solubility of a gas in a liquid and contributes to the understanding of this important phase equilibrium concept. The experimental results report the determination…

Fonsecaa, I. M. A.; Almeida, J. P. B.; Fachada, H. C.

2008-01-01

121

Aerospace gas\\/liquid separator for terrestrial applications  

Microsoft Academic Search

The space gas\\/liquid separator, a key component in the heat transport subsystem of a space reactor power system, was developed to remove helium gas from liquid lithium in zero gravity. This paper describes terrestrial applications which are a direct result of a new technology that was developed for a space power system. One application is removing air from cola syrup

Jack F. Mondt

1996-01-01

122

Gas-liquid chromatographic determination of kepone in field-collected avian tissues and eggs.  

PubMed

A procedure is described for determining Kepone (decachlorooctahydro-1,3,4-metheno-2H-cyclobuta [cd] pentalene-2-one) residues in avian egg, liver, and tissue. Samples were extracted with benzene-isopropanol, and the extract was cleaned up with fuming H2SO4-concentrated H2SO4. Kepone was separated from organochlorine pesticides and polychlorinated biphenyls on a Florisil column and analyzed by electron capture gas-liquid chromatography (GLC). The average recovery from spiked tissues was 86%. The analyses performed on 14 bald eagle carcasses and livers, 3 bald eagle eggs, and 14 osprey eggs show measurable levels which indicate that Kepone accumulates in the tissues of fish-eating birds. Residues were confirmed by GLC-mass spectrometry. PMID:74377

Stafford, C J; Reichel, W L; Swineford, D M; Prouty, R M; Gay, M L

1978-01-01

123

Gas-liquid chromatographic determination of kepone in field-collected avian tissues and eggs  

USGS Publications Warehouse

A procedure is described for determining Kepone (decachlorooctahydro-1,3,4-metheno-2H-cyclobuta [cd] pentalene-2-one) residues in avian egg, liver, and tissue. Samples were extracted with benzene-isopropanol, and the extract was cleaned up with fuming H2SO4-concentrated H2SO4. Kepone was separated from organochlorine pesticides and polychlorinated biphenyls on a Florisil column and analyzed by electron capture gas-liquid chromatography (GLC). The average recovery from spiked tissues was 86%. The analyses performed on 14 bald eagle carcasses and livers, 3 bald eagle eggs, and 14 osprey eggs show measurable levels which indicate that Kepone accumulates in the tissues of fish-eating birds. Residues were confirmed by GLC-mass spectrometry.

Stafford, C.J.; Reichel, W.L.; Swineford, D.M.; Prouty, R.M.; Gay, M.L.

1978-01-01

124

Performance improvement of Gas-Liquid Cylindrical Cyclone separator using different design for tangential inlet  

E-print Network

to the center of the cyclone and is taken out from the top. I i J Fig. 1. 1 ? Large Gas-Liquid Cylindrical Cyclone Separator; Minas Field, Indonesia (Courtesy Chevron). Applications of gas-liquid cylindrical cyclone can be in a metering loop configuration... Cyclone Separator; Minas Field, Indonesia. . . . . . . . . . 2 2. 1 Gas-Liquid Cylindrical Cyclone Application for Tluee-Phase Metering System. . . 9 2. 2 Gas-Liquid Cylindrical Cyclone Application for Multiphase Metering System- Eugene Island. . . 11...

Barbuceanu, Nicolae

2001-01-01

125

Differential scanning calorimetric analysis of edible oils: Comparison of thermal properties and chemical composition  

Microsoft Academic Search

The thermal profiles of 17 edible oil samples from different plant origins were examined by differential scanning calorimetry\\u000a (DSC). Two other confirmatory analytical techniques, namely gas-liquid chromatography (GLC) and high-performance liquid chromatography\\u000a (HPLC), were used to determine fatty acid (FA) and triacylglycerol (TAG) compositions. The FA and TAG compositions were used\\u000a to complement the DSC data. Iodine value (IV) analysis

C. P. Tan; Y. B. Che Man

2000-01-01

126

Gas-liquid critical point in ionic fluids  

E-print Network

Based on the method of collective variables we develop the statistical field theory for the study of a simple charge-asymmetric $1:z$ primitive model (SPM). It is shown that the well-known approximations for the free energy, in particular DHLL and ORPA, can be obtained within the framework of this theory. In order to study the gas-liquid critical point of SPM we propose the method for the calculation of chemical potential conjugate to the total number density which allows us to take into account the higher order fluctuation effects. As a result, the gas-liquid phase diagrams are calculated for $z=2-4$. The results demonstrate the qualitative agreement with MC simulation data: critical temperature decreases when $z$ increases and critical density increases rapidly with $z$.

O. Patsahan; I. Mryglod; T. Patsahan

2006-06-27

127

US crude oil, natural gas, and natural gas liquids reserves  

SciTech Connect

This report presents estimates of proved reserves of crude oil, natural gas, and natural gas liquids as of December 31, 1989, and production volumes for the year 1989 for the total United States and for selected states and state sub-divisions. Estimates are presented for the following four categories of natural gas: total gas (wet after lease separation), its two major components (nonassociated and associated-dissolved gas), and total dry gas (wet gas adjusted for the removal of liquids at natural gas processing plants). In addition, two components of natural gas liquids, lease condensate and natural gas plant liquids, have their reserves and production reported separately. Also included is information on indicated additional crude oil reserves and crude oil, natural gas, and lease condensate reserves in nonproducing reservoirs. 28 refs., 9 figs., 15 tabs.

Not Available

1990-10-05

128

Hydrocarbon Gas Liquids (HGL): Recent Market Trends and Issues  

EIA Publications

Over the past five years, rapid growth in U.S. onshore natural gas and oil production has led to increased volumes of natural gas plant liquids (NGPL) and liquefied refinery gases (LRG). The increasing economic importance of these volumes, as a result of their significant growth in production, has revealed the need for better data accuracy and transparency to improve the quality of historical data and projections for supply, demand, and prices of these liquids, co-products, and competing products. To reduce confusion in terminology and improve its presentation of data, EIA has worked with industry and federal and state governments to clarify gas liquid terminology and has developed the term Hydrocarbon Gas Liquids, or HGL.

2014-01-01

129

Analysis of aminophospholipid molecular species by high performance liquid chromatography  

Microsoft Academic Search

A new method is described for the separation of in- dividual molecular species of the aminophospholipids, phos- phatidylethanolamine and phosphatidylserine. Trinitrobenzene- sulfonic acid was used to derivatize both aminophospholipids and the derivatives were purified by thin-layer chromatography. A reversed-phase high performance liquid chromatography technique was developed to separate and quantify individual molecular species based upon ultraviolet detection of the at-

Francoise Hullin; Hee-Yong Kim; Norman Salem

130

Affinity membrane chromatography for the analysis and purification of proteins  

Microsoft Academic Search

Affinity chromatography is unique among separation methods as it is the only technique that permits the purification of proteins based on biological functions rather than individual physical or chemical properties. The high specificity of affinity chromatography is due to the strong interaction between the ligand and the proteins of interest. Membrane separation allows the processing of a large amount of

Hanfa Zou; Quanzhou Luo; Dongmei Zhou

2001-01-01

131

Two-phase flow characteristics in gas–liquid microreactors  

Microsoft Academic Search

Multiphase chemical microreactors require a detailed knowledge of the flow conditions inside the reaction system. This paper reports flow visualization measurements of the two-phase gas–liquid flow pattern and the liquid velocity distribution inside liquid plugs of an intermittent flow. Rectangular cross-section silicon microchannels with hydraulic diameters between 187.5 and 218?m are fabricated. Laser Induced Fluorescence (LIF) is used to determine

Severin Waelchli; Philipp Rudolf von Rohr

2006-01-01

132

CFD simulation of gas–liquid contacting in tubular reactors  

Microsoft Academic Search

Gas–liquid contacting in tubular reactors was simulated using an Eulerian–Eulerian CFD approach in which accurate interphase momentum closure relations are incorporated, bubble-induced turbulence is accounted for, and population balance equations are used to describe bubble breakage and coalescence. The ability of two breakup kernels (Luo, H., Svendsen, H.F., 1996. Theoretical model for drop and bubble breakup in turbulent dispersions. A.I.Ch.E.

K. Podila; A. M. Al Taweel; M. Koksal; A. Troshko; Y. P. Gupta

2007-01-01

133

GAS/LIQUID MEMBRANES FOR NATURAL GAS UPGRADING  

SciTech Connect

A new project was initiated this quarter to develop gas/liquid membranes for natural gas upgrading. Efforts have concentrated on legal agreements, including alternative field sites. Gas Technology Institute (GTI) is conducting this research program whose objective is to develop gas/liquid membranes for natural gas upgrading to assist DOE in achieving their goal of developing novel methods of upgrading low quality natural gas to meet pipeline specifications. Kvaerner Process Systems (KPS) and W. L. Gore & Associates (GORE) gas/liquid membrane contactors are based on expanded polytetrafluoroethylene (ePTFE) membranes acting as the contacting barrier between the contaminated gas stream and the absorbing liquid. These resilient membranes provide much greater surface area for transfer than other tower internals, with packing densities five to ten times greater, resulting in equipment 50-70% smaller and lower weight for the same treating service. The scope of the research program is to (1) build and install a laboratory- and a field-scale gas/liquid membrane absorber; (2) operate the units with a low quality natural gas feed stream for sufficient time to verify the simulation model of the contactors and to project membrane life in this severe service; and (3) conducted an economic evaluation, based on the data, to quantify the impact of the technology. Chevron, one of the major producers of natural gas, has offered to host the test at a gas treating plant. KPS will use their position as a recognized leader in the construction of commercial amine plants for building the unit along with GORE providing the membranes. GTI will provide operator and data collection support during lab- and field-testing to assure proper analytical procedures are used. Kvaerner and GTI will perform the final economic evaluation. GTI will provide project management and be responsible for reporting and interactions with DOE on this project.

Howard S. Meyer

2002-06-01

134

Thin-layer chromatography-densitometry and liquid chromatography analysis of alkaloids in leaves of Papaver somniferum under stress conditions.  

PubMed

The effect of stress conditions on the concentrations of secondary metabolites were examined during various developmental stages of Papaver somniferum plants. P. somniferum plants were grown in laboratory conditions (Budakalász). The experiment consisted of 22 treatments. Significantly different alkaloid contents can be observed under different stress conditions. In general, the alkaloid contents of plants are very low; therefore, a highly sensitive and reliable method has to be developed for analysis. The amount of alkaloids was measured by 2 separation and detection techniques. Accuracy of the thin-layer chromatography method for quantitative analysis is limited. Without purification of samples the background is too noisy. Column liquid chromatography is a sensitive and relatively inexpensive method that allows precise quantitative determination of the alkaloid content. PMID:16386012

Szabó, Beata; Lakatos, Agnes; Kõszegi, Tamás; Kátay, György; Botz, L

2005-01-01

135

Gas-Liquid Coexistence in the Primitive Model for Water  

E-print Network

We evaluate the location of the gas-liquid coexistence line and of the associated critical point for the primitive model for water (PMW), introduced by Kolafa and Nezbeda [J. Kolafa and I. Nezbeda, Mol. Phys. 61, 161 (1987)]. Besides being a simple model for a molecular network forming liquid, the PMW is representative of patchy proteins and novel colloidal particles interacting with localized directional short-range attractions. We show that the gas-liquid phase separation is metastable, i.e. it takes place in the region of the phase diagram where the crystal phase is thermodynamically favored, as in the case of articles interacting via short-range attractive spherical potentials. Differently from spherical potentials, we do not observe crystallization close to the critical point. The region of gas-liquid instability of this patchy model is significantly reduced as compared to equivalent models of spherically interacting particles, confirming the possibility of observing kinetic arrest in an homogeneous sample driven by bonding as opposed to packing.

F. Romano; P. Tartaglia; F. Sciortino

2007-05-08

136

Stability analysis of switching hyperbolic systems: the example of SMB chromatography  

E-print Network

Stability analysis of switching hyperbolic systems: the example of SMB chromatography Georges Abstract-- This paper addresses the issue of the exponential stability of hybrid hyperbolic systems chromatography, how exponential stability (in L2-norm) can be established when the switching mechanism

Bastin, Georges

137

Recycling Size Exclusion Chromatography for the Analysis and Separation of Nanocrystalline Gold  

E-print Network

Recycling Size Exclusion Chromatography for the Analysis and Separation of Nanocrystalline Gold Ali University, MS-60 6100 Main Street, Houston, Texas 77025 Recycling size exclusion chromatography (RSEC here the application of this method to gold nanocrystals stabilized by thiols. Alternate recycling

Richards-Kortum, Rebecca

138

Chromatography Theory  

NSDL National Science Digital Library

James Hardy has produced a number of presentation-style lecture modules for analytical chemistry. This is a very good module that covers the introductory theory of chromatography. The material includes information on chromatography along with plate and kinetic theories. It is a colorful and well planned presentation of the introduction to chromatography that could be used as the basis for lectures on chromatography at the introductory analytical chemistry or instrumental analysis level.

139

Acoustic probe for solid-gas-liquid suspensions. 1997 annual progress report  

SciTech Connect

'Acoustic probes have shown promise to be quite effective in determining the solid content in solid-liquid suspensions. However, the presence of small amounts of gas in the waste slurries stored in tanks across the DOE complex prevents straightforward application for characterization of these slurries. The proposed research will develop an acoustic probe for monitoring particle size and volume fraction in slurries in the absence and the presence of gas bubbles. Theoretical Analysis Accomplished: Attenuation of sound waves depends on the size distribution of the solids and the volume fraction of solids. These can in principle be calculated from attenuation measured over a range of frequencies. However, small amounts of bubbles distort the measured attenuation. A typical result from theoretical analysis for the attenuation of solid- gas-liquid systems is given in Figure 1. The total attenuation of a sound wave v(o) equals the sum of contributions by a large number of ''bins'' of particle sizes. This notion yields the following equation for the (hitherto) unknown number density of solid particles as a function of particle radius N(a): j k(o,a)N(a)da = v(o), where the kernel k(o,a) is obtained from analysis. If N(a) is given, the above equation is used to calculate the attenuation v(o). This is referred to as solving the ''forward problem''. Solving for N(a) with v(o) given is the ''inverse problem''. A complication that one faces when trying to solve the inverse problem is that the stated problem is mathematically ill-posed, i.e., small fluctuations in v(o) cause large fluctuations in the result for the number density. Therefore the problem needs to be ''regularized'', i.e., the stated problem needs to be changed slightly such as to make it well-posed. This has been done by others for gas-liquid systems in the past. This approach is currently being applied in the present project to solid-liquid systems. As is shown in Figure 2, it successfully recovers the number density that has been used in the forward problem to generate attenuation data. Having this solution technique giving reliable results for the inverse problems of both gas-liquid and solid-liquid systems, the authors shall apply this method in the near future to solid-gas-liquid systems.'

Tavlarides, L.L.; Sangani, A.S.

1997-01-01

140

Analysis of anions in beer using ion chromatography  

PubMed Central

The majority of anions found in beer are a consequence of impurities derived from the water used during the brewing process. The process of beer manufacture consists of malting, brewing and fermentation followed by maturation before filtration and finally storage. Strict quality control is required because the presence of certain anions outside strictly defined tolerance limits can affect the flavour characteristics of the finished product. The anions present were quantified using the technique of ion chromatography with the Metrohm modular system following sample preparation. The analysis produced a result of the order 200 mg l-1 for chloride, phosphate and sulphate and around 20 mg l-1 for nitrate. If the chloride level exceeds 250 mg l-1, then the sweetness of the beer is enhanced, but yeast flocculation can be hindered. An excess of sulphate can give a sharp, dry edge to hopped beers and excessive amounts of nitrate have been found to harm the yeast metabolism after conversion to the nitrite form. As water is a primary ingredient within beer, its quality and type is a fundamental factor in establishing many of the distinctive regional beers that can be found in the United Kingdom and is thus monitored carefully. PMID:18924733

Bruce, Jonathan

2002-01-01

141

Global weak solutions for a compressible gas-liquid model with well-formation interaction  

NASA Astrophysics Data System (ADS)

The objective of this work is to explore a compressible gas-liquid model designed for modeling of well flow processes. We build into the model well-reservoir interaction by allowing flow of gas between well and formation (surrounding reservoir). Inflow of gas and subsequent expansion of gas as it ascends towards the top of the well (a so-called gas kick) represents a major concern for various well operations in the context of petroleum engineering. We obtain a global existence result under suitable assumptions on the regularity of initial data and the rate function that controls the flow of gas between well and formation. Uniqueness is also obtained by imposing more regularity on the initial data. The key estimates are to obtain appropriate lower and upper bounds on the gas and liquid masses. For that purpose we introduce a transformed version of the original model that is highly convenient for analysis of the original model. In particular, in the analysis of the transformed model additional terms, representing well-formation interaction, can be treated by natural extensions of arguments that previously have been employed for the single-phase Navier-Stokes model. The analysis ensures that transition to single-phase regions do not appear when the initial state is a true gas-liquid mixture.

Evje, Steinar

142

DYNAMIC MODELING STRATEGY FOR FLOW REGIME TRANSITION IN GAS-LIQUID TWO-PHASE FLOWS  

SciTech Connect

In modeling gas-liquid two-phase flows, the concept of flow regime has been used to characterize the global interfacial structure of the flows. Nearly all constitutive relations that provide closures to the interfacial transfers in two-phase flow models, such as the two-fluid model, are often flow regime dependent. Currently, the determination of the flow regimes is primarily based on flow regime maps or transition criteria, which are developed for steady-state, fully-developed flows and widely applied in nuclear reactor system safety analysis codes, such as RELAP5. As two-phase flows are observed to be dynamic in nature (fully-developed two-phase flows generally do not exist in real applications), it is of importance to model the flow regime transition dynamically for more accurate predictions of two-phase flows. The present work aims to develop a dynamic modeling strategy for determining flow regimes in gas-liquid two-phase flows through the introduction of interfacial area transport equations (IATEs) within the framework of a two-fluid model. The IATE is a transport equation that models the interfacial area concentration by considering the creation and destruction of the interfacial area, such as the fluid particle (bubble or liquid droplet) disintegration, boiling and evaporation; and fluid particle coalescence and condensation, respectively. For the flow regimes beyond bubbly flows, a two-group IATE has been proposed, in which bubbles are divided into two groups based on their size and shape (which are correlated), namely small bubbles and large bubbles. A preliminary approach to dynamically identifying the flow regimes is provided, in which discriminators are based on the predicted information, such as the void fraction and interfacial area concentration of small bubble and large bubble groups. This method is expected to be applied to computer codes to improve their predictive capabilities of gas-liquid two-phase flows, in particular for the applications in which flow regime transition occurs.

X. Wang; X. Sun; H. Zhao

2011-09-01

143

Chiral analysis by online coupling of reversed-phase liquid chromatography to gas chromatography and mass spectrometry.  

PubMed

Enantiomeric composition of selected chiral compounds present in complex mixtures is determined by using the online coupling of reversed-phase liquid chromatography (LC) to gas chromatography (GC) and mass spectrometry. Integration of sample preparation into GC analysis, in a completely automated way, is achieved by means of the effective clean-up resulting from both the LC fractionation step and the eluent elimination provided by the through oven transfer adsorption desorption system used for LC-GC interfacing. The possibilities of the technique are illustrated through some examples concerning the stereodifferentiation in essential oils of major and minor chiral compounds via LC-GC transfer of different volume fractions, ranging from 0.5 to 1.9 ml, which show the significance of the window size for the determination of enantiomeric profiles. PMID:22517436

Barba, Carmen; Martínez, Rosa M; Calvo, Marta M; Santa-María, Guillermo; Herraiz, Marta

2012-05-01

144

Group separation and gas chromatography--mass spectrometry of conjugated steroids in plasma.  

PubMed

A method is described for analysis of metabolic profiles of conjugated steroids in plasma. Steroids are extracted by Amberlite XAD-2 or Sep-Pak C18 cartridges at 60 64 C in the presence of triethylamine sulphate and separated into unconjugated neutral and phenolic compounds, glucuronide, monosulphate and disulphate conjugate groups by chromatography on the lipophilic strong anion exchanger triethylaminohydroxypropyl Sephadex LH-20 (TEAP-LH-20). The conjugate moiety is hydrolyzed by brief enzymatic or solvolytic procedures and released steroids are separated into a neutral and a phenolic fraction on TEAP-LH-20. The O-methyloxime and trimethylsilyl ether derivatives of the steroids are analyzed by glass capillary column gas liquid chromatography and gas chromatography mass spectrometry. Examples of the application of the method to analysis of conjugated steroids in plasma from pregnant women are given. PMID:6827836

Axelson, M; Sahlberg, B L

1983-03-01

145

Industrial application of green chromatography - II. Separation and analysis of preservatives in skincare products using subcritical water chromatography.  

PubMed

Several high-temperature liquid chromatography (HTLC) and subcritical water chromatography (SBWC) methods have been successfully developed in this study for separation and analysis of preservatives contained in Olay skincare creams. Efficient separation and quantitative analysis of preservatives have been achieved on four commercially available ZirChrom and Waters XBridge columns at temperatures ranging from 100 to 200°C. The quantification results obtained by both HTLC and SBWC methods developed for preservatives analysis are accurate and reproducible. A large number of replicate HTLC and SBWC runs also indicate no significant system building-up or interference for skincare cream analysis. Compared with traditional HPLC separation carried out at ambient temperature, the HTLC methods can save up to 90% methanol required in the HPLC mobile phase. However, the SBWC methods developed in this project completely eliminated the use of toxic organic solvents required in the HPLC mobile phase, thus saving a significant amount of money and making the environment greener. Although both homemade and commercial systems can accomplish SBWC separations, the SBWC methods using the commercial system for preservative analysis are recommended for industrial applications because they can be directly applied in industrial plant settings. PMID:22762371

Yang, Y; Kapalavavi, B; Gujjar, L; Hadrous, S; Marple, R; Gamsky, C

2012-10-01

146

AN EPA MANUAL FOR ORGANICS ANALYSIS USING GAS CHROMATOGRAPHY-MASS SPECTROMETRY  

EPA Science Inventory

This procedural manual defines the areas of applicability of gas chromatography-mass spectrometry in environmental analysis. The manual includes sample preparation methods specifically adapted to this measurement technique, data processing and interpretation methods, quality cont...

147

Analysis of chemical signals in red fire ants by gas chromatography and pattern recognition techniques  

Technology Transfer Automated Retrieval System (TEKTRAN)

The combination of gas chromatography and pattern recognition (GC/PR) analysis is a powerful tool for investigating complicated biological problems. Clustering, mapping, discriminant development, etc. are necessary to analyze realistically large chromatographic data sets and to seek meaningful relat...

148

APPLICATION OF CAPILLARY SUPERCRITICAL FLUID CHROMATOGRAPHY TO THE ANALYSIS OF A MIDDLE DISTILLATE FUEL  

EPA Science Inventory

The paper describes the application of capillary supercritical fluid chromatography (SFC) to the analysis of a middle distillate fuel. Small diameter (50 micrometer i.d.) fused silica capillary columns coated with crosslinked 50% phenyl polymethylsiloxane provided high separation...

149

GAS/LIQUID MEMBRANES FOR NATURAL GAS UPGRADING  

SciTech Connect

Efforts this quarter have concentrated on legal agreements, including alternative field sites. Preliminary design of the bench-scale equipment has been initiated. Gas Technology Institute (GTI) is conducting this research program whose objective is to develop gas/liquid membranes for natural gas upgrading to assist DOE in achieving their goal of developing novel methods of upgrading low quality natural gas to meet pipeline specifications. Kvaerner Process Systems (KPS) and W. L. Gore & Associates (GORE) gas/liquid membrane contactors are based on expanded polytetrafluoroethylene (ePTFE) membranes acting as the contacting barrier between the contaminated gas stream and the absorbing liquid. These resilient membranes provide much greater surface area for transfer than other tower internals, with packing densities five to ten times greater, resulting in equipment 50--70% smaller and lower weight for the same treating service. The scope of the research program is to (1) build and install a laboratory- and a field-scale gas/liquid membrane absorber; (2) operate the units with a low quality natural gas feed stream for sufficient time to verify the simulation model of the contactors and to project membrane life in this severe service; and (3) conducted an economic evaluation, based on the data, to quantify the impact of the technology. Chevron, one of the major producers of natural gas, has offered to host the test at a gas treating plant. KPS will use their position as a recognized leader in the construction of commercial amine plants for building the unit along with GORE providing the membranes. GTI will provide operator and data collection support during lab- and field-testing to assure proper analytical procedures are used. Kvaerner and GTI will perform the final economic evaluation. GTI will provide project management and be responsible for reporting and interactions with DOE on this project.

Howard S. Meyer

2002-06-01

150

GAS/LIQUID MEMBRANES FOR NATURAL GAS UPGRADING  

SciTech Connect

Gas Technology Institute (GTI) is conducting this research program whose objective is to develop gas/liquid membranes for natural gas upgrading to assist DOE in achieving their goal of developing novel methods of upgrading low quality natural gas to meet pipeline specifications. Kvaerner Process Systems (KPS) and W. L. Gore & Associates (GORE) gas/liquid membrane contactors are based on expanded polytetrafluoroethylene (ePTFE) membranes acting as the contacting barrier between the contaminated gas stream and the absorbing liquid. These resilient membranes provide much greater surface area for transfer than other tower internals, with packing densities five to ten times greater, resulting in equipment 50-70% smaller and lower weight for the same treating service. The scope of the research program is to (1) build and install a laboratory- and a field-scale gas/liquid membrane absorber; (2) operate the units with a low quality natural gas feed stream for sufficient time to verify the simulation model of the contactors and to project membrane life in this severe service; and (3) conducted an economic evaluation, based on the data, to quantify the impact of the technology. Chevron, one of the major producers of natural gas, has offered to host the test at a gas treating plant. KPS will use their position as a recognized leader in the construction of commercial amine plants for building the unit along with GORE providing the membranes. GTI will provide operator and data collection support during lab- and field-testing to assure proper analytical procedures are used. KPS and GTI will perform the final economic evaluation. GTI will provide project management and be responsible for reporting and interactions with DOE on this project. Efforts this quarter have concentrated on legal agreements, including alternative field sites. Preliminary design of the bench-scale equipment continues.

Howard S. Meyer

2002-10-01

151

GAS/LIQUID MEMBRANES FOR NATURAL GAS UPGRADING  

SciTech Connect

Gas Technology Institute (GTI) is conducting this research program whose objective is to develop gas/liquid membranes for natural gas upgrading to assist DOE in achieving their goal of developing novel methods of upgrading low quality natural gas to meet pipeline specifications. Kvaerner Process Systems (KPS) and W. L. Gore & Associates (GORE) gas/liquid membrane contactors are based on expanded polytetrafluoroethylene (ePTFE) membranes acting as the contacting barrier between the contaminated gas stream and the absorbing liquid. These resilient membranes provide much greater surface area for transfer than other tower internals, with packing densities five to ten times greater, resulting in equipment 50-70% smaller and lower weight for the same treating service. The scope of the research program is to (1) build and install a laboratory- and a field-scale gas/liquid membrane absorber; (2) operate the units with a low quality natural gas feed stream for sufficient time to verify the simulation model of the contactors and to project membrane life in this severe service; and (3) conducted an economic evaluation, based on the data, to quantify the impact of the technology. Chevron, one of the major producers of natural gas, has offered to host the test at a gas treating plant. KPS will use their position as a recognized leader in the construction of commercial amine plants for building the unit along with GORE providing the membranes. GTI will provide operator and data collection support during lab- and field-testing to assure proper analytical procedures are used. KPS and GTI will perform the final economic evaluation. GTI will provide project management and be responsible for reporting and interactions with DOE on this project. Efforts this quarter have concentrated on field site selection. ChevronTexaco has nominated their Headlee Gas Plant in Odessa, TX for a commercial-scale dehydration test. Potting and module materials testing were initiated. Preliminary design of the bench-scale equipment continues.

Howard S. Meyer

2003-04-01

152

GAS/LIQUID MEMBRANES FOR NATURAL GAS UPGRADING  

SciTech Connect

Efforts this quarter have concentrated on legal agreements, including alternative field sites. Preliminary design of the bench-scale equipment continues. Gas Technology Institute (GTI) is conducting this research program whose objective is to develop gas/liquid membranes for natural gas upgrading to assist DOE in achieving their goal of developing novel methods of upgrading low quality natural gas to meet pipeline specifications. Kvaerner Process Systems (KPS) and W. L. Gore & Associates (GORE) gas/liquid membrane contactors are based on expanded polytetrafluoroethylene (ePTFE) membranes acting as the contacting barrier between the contaminated gas stream and the absorbing liquid. These resilient membranes provide much greater surface area for transfer than other tower internals, with packing densities five to ten times greater, resulting in equipment 50--70% smaller and lower weight for the same treating service. The scope of the research program is to (1) build and install a laboratory- and a field-scale gas/liquid membrane absorber; (2) operate the units with a low quality natural gas feed stream for sufficient time to verify the simulation model of the contactors and to project membrane life in this severe service; and (3) conducted an economic evaluation, based on the data, to quantify the impact of the technology. Chevron, one of the major producers of natural gas, has offered to host the test at a gas treating plant. KPS will use their position as a recognized leader in the construction of commercial amine plants for building the unit along with GORE providing the membranes. GTI will provide operator and data collection support during lab- and field-testing to assure proper analytical procedures are used. Kvaerner and GTI will perform the final economic evaluation. GTI will provide project management and be responsible for reporting and interactions with DOE on this project.

Howard S. Meyer

2002-06-30

153

GAS/LIQUID MEMBRANES FOR NATURAL GAS UPGRADING  

SciTech Connect

Gas Technology Institute (GTI) is conducting this research program whose objective is to develop gas/liquid membranes for natural gas upgrading to assist DOE in achieving their goal of developing novel methods of upgrading low quality natural gas to meet pipeline specifications. Kvaerner Process Systems (KPS) and W. L. Gore & Associates (GORE) gas/liquid membrane contactors are based on expanded polytetrafluoroethylene (ePTFE) membranes acting as the contacting barrier between the contaminated gas stream and the absorbing liquid. These resilient membranes provide much greater surface area for transfer than other tower internals, with packing densities five to ten times greater, resulting in equipment 50-70% smaller and lower weight for the same treating service. The scope of the research program is to (1) build and install a laboratory- and a field-scale gas/liquid membrane absorber; (2) operate the units with a low quality natural gas feed stream for sufficient time to verify the simulation model of the contactors and to project membrane life in this severe service; and (3) conducted an economic evaluation, based on the data, to quantify the impact of the technology. Chevron, one of the major producers of natural gas, has offered to host the test at a gas treating plant. KPS will use their position as a recognized leader in the construction of commercial amine plants for building the unit along with GORE providing the membranes. GTI will provide operator and data collection support during lab- and field-testing to assure proper analytical procedures are used. Kvaerner and GTI will perform the final economic evaluation. GTI will provide project management and be responsible for reporting and interactions with DOE on this project. Efforts this quarter have concentrated on legal agreements, including alternative field sites. Preliminary design of the bench-scale equipment continues.

Howard S. Meyer

2003-01-01

154

Degradation of gas-liquid gliding arc discharge on Acid Orange II.  

PubMed

The effects of pH value, initial concentration of dye solution and temperature on the degradation efficiency of Acid Orange II (AO7) using gas-liquid gliding arc discharge were investigated. The influences of pH value and temperature on degradation efficiency were not apparent. Increasing initial solution concentration caused the decrease of degradation rate and the increase of absolute degradation quantity. Considering energy efficiency and absolute degradation quantity, the gas-liquid gliding arc discharge is fit for treating high concentration organic wastewater. A possible mineralization pathway was proposed through the analysis of intermediate products detected by gas chromatograph coupled with mass spectrophotometer (GC-MS) and ion chromatograph (IC). Hydroxyl radicals reacted with the azo linkage-bearing carbon of a hydroxy-substituted ring, leading to the cleavage of -C-N- and degradation of AO7. The solution biodegradability was significantly improved (BOD(5)/COD from 0.02 to 0.43). The toxicity of intermediate products was lower than that of the initial Acid Orange II. PMID:18321644

Yan, J H; Liu, Y N; Bo, Zh; Li, X D; Cen, K F

2008-09-15

155

Advances in understanding and modeling the gas–liquid mass transfer in shake flasks  

Microsoft Academic Search

The gas–liquid mass transfer in 250ml shake flasks has previously been sucessfully modelled on basis of Higbie’s penetration theory. The current contribution presents advances in understanding and modelling the gas–liquid mass transfer in shake flasks at waterlike liquid viscosity in flask sizes between 50 and 1000ml. An experimental investigation of the maximum gas–liquid mass transfer capacity OTRmax using the sodium

Ulrike Maier; Mario Losen; Jochen Büchs

2004-01-01

156

ORGANIC WATER POLLUTANT ANALYSIS BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY  

EPA Science Inventory

Gas chromatography-mass spectrometry is a widely used technique for the identification of organic chemicals in water. This paper describes the gas chromatograph-mass spectrometer system, the preparation and separation of samples, the selection of ionizing processes, the integrati...

157

ANALYSIS OF ELECTROLESS NICKEL SOLUTIONS BY ANION CHROMATOGRAPHY  

EPA Science Inventory

The principal appeal of ion chromatography (IC) as analytical technique lies in the ability to rapidly analyze a mixture of ions of widely varying concentrations and properties in a single elution. It is therefore not surprising that IC has been hampered by the similar ion exchan...

158

HD gas analysis with Gas Chromatography and Quadrupole Mass Spectrometer  

E-print Network

A gas analyzer system has been developed to analyze Hydrogen-Deuteride (HD) gas for producing frozen-spin polarized HD targets, which are used for hadron photoproduction experiments at SPring-8. Small amounts of ortho-H$_{2}$ and para-D$_{2}$ gas mixtures ($\\sim$0.01%) in the purified HD gas are a key to realize a frozen-spin polarized target. In order to obtain reliable concentrations of these gas mixtures in the HD gas, we produced a new gas analyzer system combining two independent measurements with the gas chromatography and the QMS. The para-H$_{2}$, ortho-H$_{2}$, HD, and D$_{2}$ are separated using the retention time of the gas chromatography and the mass/charge. It is found that the new gas analyzer system can measure small concentrations of $\\sim$0.01% for the otho-H$_2$ and D$_2$ with good S/N ratios.

Ohta, T; Didelez, J -P; Fujiwara, M; Fukuda, K; Kohri, H; Kunimatsu, T; Morisaki, C; Ono, S; Rouille, G; Tanaka, M; Ueda, K; Uraki, M; Utsuro, M; Wang, S Y; Yosoi, M

2011-01-01

159

HD gas analysis with Gas Chromatography and Quadrupole Mass Spectrometer  

E-print Network

A gas analyzer system has been developed to analyze Hydrogen-Deuteride (HD) gas for producing frozen-spin polarized HD targets, which are used for hadron photoproduction experiments at SPring-8. Small amounts of ortho-H$_{2}$ and para-D$_{2}$ gas mixtures ($\\sim$0.01%) in the purified HD gas are a key to realize a frozen-spin polarized target. In order to obtain reliable concentrations of these gas mixtures in the HD gas, we produced a new gas analyzer system combining two independent measurements with the gas chromatography and the QMS. The para-H$_{2}$, ortho-H$_{2}$, HD, and D$_{2}$ are separated using the retention time of the gas chromatography and the mass/charge. It is found that the new gas analyzer system can measure small concentrations of $\\sim$0.01% for the otho-H$_2$ and D$_2$ with good S/N ratios.

T. Ohta; S. Bouchigny; J. -P. Didelez; M. Fujiwara; K. Fukuda; H. Kohri; T. Kunimatsu; C. Morisaki; S. Ono; G. Rouille; M. Tanaka; K. Ueda; M. Uraki; M. Utsuro; S. Y. Wang; M. Yosoi

2011-01-28

160

Analysis of long chain sultones by thin layer chromatography  

Microsoft Academic Search

and Summary  The separation and semiquantitative estimation of nine C14 sultones by thin layer chromatography (TLC) on silica gel is reported. Vapor phase charring gives detection limits of several\\u000a ppm in olefin sulfonate, ethoxylated alcohol sulfates, and formulated products. Isopropyl ether is the solvent of choice,\\u000a and two-dimensional TLC with this and a chlorinated solvent mixture gives an exclusive sultone area,

T. Wolf; B. P. McPherson

1977-01-01

161

Analysis of polychlorinated biphenyls (PCB) by glass capillary gas chromatography  

Microsoft Academic Search

Die Zusammensetzung sieben technischer Gemische polychlorierter Biphenyle (PCB) mit unterschiedlichem Chlorierungsgrad (Aroclor- [Monsanto, USA] und Clophen A- [Bayer, Bundesrepublik Deutschland]-Typen) wurde mit hochauflösender Gas-Chromatographie mit Elektroneneinfang-Detektion in Dünnfilm-Glascapillaren mit Methylpolysiloxan (SE 30) und gereinigtem Apiezon L als flüssiger Phase untersucht. Die Identifizierung der Einzelkomponenten erfolgte durch chromatographischen Vergleich mit definierten Referenzsubstanzen oder Vergleich der aus Inkrementen berechneten Retentionsindices. Für die

K. Ballschmiter; M. Zell

1980-01-01

162

GAS/LIQUID MEMBRANES FOR NATURAL GAS UPGRADING  

SciTech Connect

Gas Technology Institute (GTI) is conducting this research program whose objective is to develop gas/liquid membranes for natural gas upgrading to assist DOE in achieving their goal of developing novel methods of upgrading low quality natural gas to meet pipeline specifications. Kvaerner Process Systems (KPS) and W. L. Gore & Associates (GORE) gas/liquid membrane contactors are based on expanded polytetrafluoroethylene (ePTFE) membranes acting as the contacting barrier between the contaminated gas stream and the absorbing liquid. These resilient membranes provide much greater surface area for transfer than other tower internals, with packing densities five to ten times greater, resulting in equipment 50-70% smaller and lower weight for the same treating service. The scope of the research program is to (1) build and install a laboratory- and a field-scale gas/liquid membrane absorber; (2) operate the units with a low quality natural gas feed stream for sufficient time to verify the simulation model of the contactors and to project membrane life in this severe service; and (3) conducted an economic evaluation, based on the data, to quantify the impact of the technology. Chevron, one of the major producers of natural gas, has offered to host the test at a gas treating plant. KPS will use their position as a recognized leader in the construction of commercial amine plants for building the unit along with GORE providing the membranes. GTI will provide operator and data collection support during lab- and field-testing to assure proper analytical procedures are used. Kvaerner and GTI will perform the final economic evaluation. GTI will provide project management and be responsible for reporting and interactions with DOE on this project. Efforts this quarter have concentrated on field site selection. ChevronTexaco has nominated their Headlee Gas Plant in Odessa, TX for a commercial-scale dehydration test. Design and cost estimation for this new site are underway. A HazOp review was conducted. Potting and module materials testing continued. Preliminary design of the bench-scale equipment continues. A status meeting was held in Morgantown, WV with the DOE Project Manager.

Howard S. Meyer

2003-10-01

163

GAS/LIQUID MEMBRANES FOR NATURAL GAS UPGRADING  

SciTech Connect

Gas Technology Institute (GTI) is conducting this research program whose objective is to develop gas/liquid membranes for natural gas upgrading to assist DOE in achieving their goal of developing novel methods of upgrading low quality natural gas to meet pipeline specifications. Kvaerner Process Systems (KPS) and W. L. Gore & Associates (GORE) gas/liquid membrane contactors are based on expanded polytetrafluoroethylene (ePTFE) membranes acting as the contacting barrier between the contaminated gas stream and the absorbing liquid. These resilient membranes provide much greater surface area for transfer than other tower internals, with packing densities five to ten times greater, resulting in equipment 50-70% smaller and lower weight for the same treating service. The scope of the research program is to (1) build and install a laboratory- and a field-scale gas/liquid membrane absorber; (2) operate the units with a low quality natural gas feed stream for sufficient time to verify the simulation model of the contactors and to project membrane life in this severe service; and (3) conducted an economic evaluation, based on the data, to quantify the impact of the technology. Chevron, one of the major producers of natural gas, has offered to host the test at a gas treating plant. KPS will use their position as a recognized leader in the construction of commercial amine plants for building the unit along with GORE providing the membranes. GTI will provide operator and data collection support during lab- and field-testing to assure proper analytical procedures are used. Kvaerner and GTI will perform the final economic evaluation. GTI will provide project management and be responsible for reporting and interactions with DOE on this project. Efforts this quarter have concentrated on field site selection. ChevronTexaco has nominated their Headlee Gas Plant in Odessa, TX for a commercial-scale dehydration test. Design and cost estimation for this new site are underway. Potting and module materials testing continued. Preliminary design of the bench-scale equipment continues.

Howard S. Meyer

2003-07-01

164

The application of a non-thermal plasma generated by gas-liquid gliding arc discharge in sterilization  

NASA Astrophysics Data System (ADS)

Gliding arc discharge has been investigated in recent years as an innovative physicochemical technique for contaminated water treatment at atmospheric pressure and ambient temperature. In this study we tested a gas-liquid gliding arc discharge reactor, the bacterial suspension of which was treated circularly. When the bacterial suspension was passed through the electrodes and circulated at defined flow rates, almost 100% of the bacteria were killed in less than 3.0 min. Experimental results showed that it is possible to achieve an abatement of 7.0 decimal logarithm units within only 30 s. Circulation flow rates and types of feeding gas caused a certain impact on bacteria inactivation, but the influences are not obvious. So, under the promise of sterilization effect, industrial applications can select their appropriate operating conditions. All inactivation curves presented the same three-phase profile showing an apparent sterilization effect. Analysis of the scanning electron microscope images of bacterial cells supports the speculation that the gas-liquid gliding arc discharge plasma is acting under various mechanisms driven essentially by oxidation and the effect of electric field. These results enhance the possibility of applying gas-liquid gliding arc discharge decontamination systems to disinfect bacterial-contaminated water. Furthermore, correlational research indicates the potential applications of this technology in rapid sterilization of medical devices, spacecraft and food.

Du, Chang Ming; Wang, Jing; Zhang, Lu; Xia Li, Hong; Liu, Hui; Xiong, Ya

2012-01-01

165

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

PubMed

Twenty-six resins from six botanical sources belonging to the class Magnoliopsida were compared based on gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry data. The extracts were analysed by GC after silylation and by reversed phase LC combined with atmospheric pressure photoionisation (APPI) mass spectrometry. The chromatograms were re-organized in data matrices, where each sample was represented by a single column comprising 2755 observations (intensity, time, m/z) in GC-MS and 360 observations in LC-MS. A simple comparison of resin fingerprints was attempted by organizing data according to a three dimensional bubble chart (retention time against m/z where each point was a bubble which size represented the ion intensity) where it is possible to easily superimpose the fingerprints. Thus the common and different species can be easily observed enabling to classify the resins. Hierarchical cluster analysis based on characteristics of GC-MS and LC-MS profiles affords a complete description of the classes of the resins and shows that 26 resins are divided into five main clusters Commiphora mukul, Daniella oliveri, Gardenia gummifera, Canarium madagascariensis, Boswellia dalzielii and Boswellia serrata, respectively. In conclusion, the proposed method has been applied to three other resinous samples from the Burseraceae family to evaluate their alteration state. PMID:22885042

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

2012-09-21

166

On The Validity of the Assumed PDF Method for Modeling Binary Mixing/Reaction of Evaporated Vapor in GAS/Liquid-Droplet Turbulent Shear Flow  

NASA Technical Reports Server (NTRS)

An Investigation of the statistical description of binary mixing and/or reaction between a carrier gas and an evaporated vapor species in two-phase gas-liquid turbulent flows is perfomed through both theroetical analysis and comparisons with results from direct numerical simulations (DNS) of a two-phase mixing layer.

Miller, R. S.; Bellan, J.

1997-01-01

167

Flameless atomic absorption (FAA) and gas-liquid chromatographic studies in arsenic bioanalysis.  

PubMed Central

Procedures for assessment of arsenic in soft tissue by use of flameless atomic absorption (FAA) and gas-liquid chromatography (GLC), have been evolved, with special emphasis on the analytical distinction among inorganic, monomethyl-, and dimethylarsenic in several oxidation states. The chemical bases for such speciation reside in several properties of the arsenicals under consideration: (1) pentavalent inorganic arsenic, methylarsonic, and cacodylic acid are not extracted from tissue matter made strongly acid with hydrochloric acid, while the corresponding trivalent forms (as halides) are extracted; (2) chloroform extracts of samples treated under reducing conditions (HCl-KI) retain organoarsenicals when these extracts are re-extracted with water, but do not when aqueous solutions of oxidants are employed; (3) reduced cacodylate (dimethylarsinous acid) is not detected in the graphite furnace of an FAA unit under conditions selected, while cacodylate can be so detected. For GLC studies, monomethyl- and dimethylarsenic are simultaneously measured as the diethyldithiocarbamate complexes with an instrument equipped for electron-capture detection and containing a glass column packed with silanized 5% OV-17 on Anakrom A.S. PMID:908312

Mushak, P; Dessauer, K; Walls, E L

1977-01-01

168

A variational approach to motion of triple junction of gas, liquid and solid  

E-print Network

A variational approach to motion of triple junction of gas, liquid and solid Kensuke Yokoia;b;c;1 a to deal with motion of triple junctions of gas, liquid (or two kinds of uid) and solid based on the level set method [1{4]. In Eulerian framework, to simulate interaction between a moving solid object

Soatto, Stefano

169

Effect of Pulsing on Reaction Outcome in a Gas-Liquid Catalytic Packed-Bed Reactor  

E-print Network

Effect of Pulsing on Reaction Outcome in a Gas-Liquid Catalytic Packed-Bed Reactor Ruiyun Wu, Mark of trickle-beds (i.e., cocurrent gas-liquid packed-bed reactors) at least since Weekman and Myers (1964 regime when pulsing was observed at a particular point. Chou et al. (1977) also adopted this criterion

McCready, Mark J.

170

CFD Modeling of Gas-Liquid Flows in Water Electrolysis Units  

Microsoft Academic Search

This paper presents the results of computational fluid dynamics (CFD) modeling of gas - liquid flows in water electrolysis systems. CFD is used as a cost-effective design tool at Stuart Energy Systems Corporation (SESC) to opti mize the performance of different water electrolysis units produced by SESC. General-purpose CFD software is used as a framework for analyzing the gas -liquid

Vladimir AGRANAT; Andrei TCHOUVELEV

171

Decomposition of phenol by hybrid gas\\/liquid electrical discharge reactors with zeolite catalysts  

Microsoft Academic Search

Application of hybrid gas\\/liquid electrical discharge reactors and a liquid phase direct electrical discharge reactor for degradation of phenol in the presence and absence of zeolites have been investigated. Hybrid gas\\/liquid electrical discharges involve simultaneous high voltage electrical discharges in water and in the gas phase above the water surface leading to the additional OH radicals in the liquid phase

Hrvoje Kuši?; Natalija Koprivanac; Bruce R. Locke

2005-01-01

172

Proteomic Analysis of SARS Associated Coronavirus Using Two-Dimensional Liquid Chromatography Mass Spectrometry and  

E-print Network

in the analysis of other viruses. Keywords: coronavirus · proteome · mass spectrometry · glycosylationProteomic Analysis of SARS Associated Coronavirus Using Two-Dimensional Liquid Chromatography Mass Spectrometry and One-Dimensional Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis Followed by Mass

Tian, Weidong

173

Digitally Enhanced Thin-Layer Chromatography: An Inexpensive, New Technique for Qualitative and Quantitative Analysis  

ERIC Educational Resources Information Center

A study conducted shows that if digital photography is combined with regular thin-layer chromatography (TLC), it could perform highly improved qualitative analysis as well as make accurate quantitative analysis possible for a much lower cost than commercial equipment. The findings suggest that digitally enhanced TLC (DE-TLC) is low-cost and easy…

Hess, Amber Victoria Irish

2007-01-01

174

A high-power ultrasonic microreactor and its application in gas-liquid mass transfer intensification.  

PubMed

The combination of ultrasound and microreactor is an emerging and promising area, but the report of designing high-power ultrasonic microreactor (USMR) is still limited. This work presents a robust, high-power and highly efficient USMR by directly coupling a microreactor plate with a Langevin-type transducer. The USMR is designed as a longitudinal half wavelength resonator, for which the antinode plane of the highest sound intensity is located at the microreactor. According to one dimension design theory, numerical simulation and impedance analysis, a USMR with a maximum power of 100 W and a resonance frequency of 20 kHz was built. The strong and uniform sound field in the USMR was then applied to intensify gas-liquid mass transfer of slug flow in a microfluidic channel. Non-inertial cavitation with multiple surface wave oscillation was excited on the slug bubbles, enhancing the overall mass transfer coefficient by 3.3-5.7 times. PMID:25537767

Dong, Zhengya; Yao, Chaoqun; Zhang, Xiaoli; Xu, Jie; Chen, Guangwen; Zhao, Yuchao; Yuan, Quan

2015-02-21

175

Design of a Gas-Liquid Unbaffled Stirred Tank with a Concave Blade Impeller  

NASA Astrophysics Data System (ADS)

Experimental investigation of unbaffled multiphase (gas-liquid) stirred tanks is conducted with the use of a concave blade impeller to analyze mass transfer, gassed power, and gas holdup. The experiments are carried out with various impeller diameter to tank diameter ratios and impeller clearances. The design criterion for the mass transfer rate is proposed, and its prediction capability is found to be satisfactory. The results show that the gassed power is dependent on the impeller diameter to tank diameter ratio and impeller clearance. The design criteria for gassed power to ungassed power ratio and gas holdup are also introduced. Multiphase modeling is done by employing the computational fluid dynamics (CFD) techniques to observe the characteristic flow pattern transition and to carry out a qualitative analysis of the mass transfer rate.

Devi, T. T.; Kumar, Bimlesh

2015-01-01

176

Compositional sugar analysis of antitumor polysaccharides by high performance liquid chromatography and gas chromatography  

Microsoft Academic Search

Carbohydrate analysis is important in studying structure and activity of complex polysaccharides. New analytical method was\\u000a applied to get an information on the composition of polysaccharides showing antitumor activity. Monosaccharides were labeled\\u000a with 7-amino-1,3-naphthalenedisulfonic acid (7-AGA) by reductive amination and separated by HPLC. Five kinds of polysaccharides\\u000a fromBasidiomycetes were hydrolyzed and analyzed in combination with electrophoresis and HPLC. At the

Yeong Shik Kim; Kyung Shin Park; Ho Koon Park; Sung Whan Kim

1994-01-01

177

Chromatographic analysis of polyglycerols and their fatty acid esters  

Microsoft Academic Search

Polyglycerols and their fatty acid esters have been analyzed by gas-liquid chromatography (GLC) as trimethylsilyl ether derivatives.\\u000a Linear diglycerols and triglycerols were isolated from commercial polyglycerols by vacuum distillation. Mono- and di-fatty\\u000a acid esters were synthesized in the laboratory. Two isomers of diglycerol have been separated and identified. GLC analysis\\u000a was carried out on columns packed with 3% JXR on

M. R. Sahasrabudhe

1967-01-01

178

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

PubMed

Spirit-based beverages are alcoholic drinks; their production processes are dependent on the type and origin of raw materials. The composition of this complex matrix is difficult to analyze, and scientists commonly choose gas chromatography techniques for this reason. With a wide selection of extraction methods and detectors it is possible to provide qualitative and quantitative analysis for many chemical compounds with various functional groups. This article describes different types of gas chromatography techniques and their most commonly used associated extraction techniques (e.g., LLE, SPME, SPE, SFE, and SBME) and detectors (MS, TOFMS, FID, ECD, NPD, AED, O or EPD). Additionally, brief characteristics of internationally popular spirit-based beverages and application of gas chromatography to the analysis of selected alcoholic drinks are presented. PMID:25849822

Wi?niewska, Paulina; ?liwi?ska, Magdalena; Dymerski, Tomasz; Wardencki, Waldemar; Namie?nik, Jacek

2015-07-01

179

Dynamic Modeling Strategy for Flow Regime Transition in Gas-Liquid Two-Phase Flows  

SciTech Connect

In modeling gas-liquid two-phase flows, the concept of flow regimes has been widely used to characterize the global interfacial structure of the flows. Nearly all constitutive relations that provide closures to the interfacial transfers in two-phase flow models, such as the two-fluid model, are flow regime dependent. Current nuclear reactor safety analysis codes, such as RELAP5, classify flow regimes using flow regime maps or transition criteria that were developed for steady-state, fully-developed flows. As twophase flows are dynamic in nature, it is important to model the flow regime transitions dynamically to more accurately predict the two-phase flows. The present work aims to develop a dynamic modeling strategy to determine flow regimes in gas-liquid two-phase flows through introduction of interfacial area transport equations (IATEs) within the framework of a two-fluid model. The IATE is a transport equation that models the interfacial area concentration by considering the creation of the interfacial area, fluid particle (bubble or liquid droplet) disintegration, boiling and evaporation, and the destruction of the interfacial area, fluid particle coalescence and condensation. For flow regimes beyond bubbly flows, a two-group IATE has been proposed, in which bubbles are divided into two groups based on their size and shapes, namely group-1 and group-2 bubbles. A preliminary approach to dynamically identify the flow regimes is discussed, in which discriminator s are based on the predicted information, such as the void fraction and interfacial area concentration. The flow regime predicted with this method shows good agreement with the experimental observations.

Xia Wang; Xiaodong Sun; Benjamin Doup; Haihua Zhao

2012-12-01

180

Glass flask air sample analysis through Gas Chromatography in India: Implications for constraining CO2 surface fluxes  

E-print Network

Glass flask air sample analysis through Gas Chromatography in India: Implications for constraining-106; Indian Institute of Tropical Meteorology (IITM), Pune, India Analytical facility: Gas Chromatography, it is imperative that India also contribute to the analysis. Recently we have established a Gas Chromatograph (GC

181

Gas Chromatography  

NSDL National Science Digital Library

This is a website from the US Environmental Protection Agency that explains Gas Chromatography for those interested in environmental analysis. The level of the material assumes some user background in the field.

182

COMPARATIVE EVALUATION OF GC/MS (GAS CHROMATOGRAPHY/MASS SPECTROMETRY) DATA ANALYSIS PROCESSING  

EPA Science Inventory

Mass spectra obtained by fused silica capillary gas chromatography/mass spectrometry/data system (GC/MS/DS) analysis of mixtures of organic chemicals adsorbed on Tenax GC cartridges was subjected to manual and automated interpretative techniques. Synthetic mixtures (85 chemicals ...

183

The use of thin-layer chromatography in the analysis of lubricating oils  

Microsoft Academic Search

Summary A report is given on the application of thin-layer chromatography to the analysis of additives in lubricating oils. The separation and identification of antioxidants, phenates, sulphonates, zinc dialkyl dithiophosphates and polymeric additives is described. A measurement of additive depletion in used oils is possible by comparison of corresponding chromatograms.

R. Amos

1968-01-01

184

Application of thin-layer chromatography for analysis of heavy petroleum products  

Microsoft Academic Search

Thin-layer chromatography (TLC), which is commonly used in the analysis of complex mixtures, is seldom used in the investigation of petroleum products, maybe the most complex objects. In particular, with respect to heavy petroleum products, no such information has been found in the literature. At the same time, the simplicity, economy, and efficiency of this technique in comparison with column

A. M. Botvin'eva

1984-01-01

185

Analysis and Identification of Acid-Base Indicator Dyes by Thin-Layer Chromatography  

ERIC Educational Resources Information Center

Thin-layer chromatography (TLC) is a very simple and effective technique that is used by chemists by different purposes, including the monitoring of the progress of a reaction. TLC can also be easily used for the analysis and identification of various acid-base indicator dyes.

Clark, Daniel D.

2007-01-01

186

Optimised determination of clobazam in human plasma with extraction and high-performance liquid chromatography analysis  

Microsoft Academic Search

The analysis of clobazam by high-performance liquid chromatography and UV detection is described herein. After adding an internal standard, 600 ?l of plasma were extracted under basic conditions onto disposable cartridges packed with celite. The organic extract was then evaporated to dryness and the residue reconstituted in 200 ?l of mobile phase. A 20 ?l aliquot was injected into chromatograph.

A. Bolner; F. Tagliaro; A. Lomeo

2001-01-01

187

New trends in fast liquid chromatography for food and environmental analysis.  

PubMed

There is an increasing need for applications in food and environmental areas able to cope with a large number of analytes in very complex matrices. The new analytical procedures demand sensitivity, robustness and high resolution within an acceptable analysis time. The purpose of this review is to describe new trends based on fast liquid chromatography applied to the food and environmental analysis. It includes different column technologies, such as monolithic, sub-2 ?m, porous shell, as well as different stationary phases such as reversed phase (C8 and C18), hydrophilic interaction liquid chromatography (HILIC) and fluorinated columns. Additionally, recent sample extraction and clean-up methodologies applied to reduce sample manipulation and total analysis time in food and environmental analysis--QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe), on line solid phase extraction coupled to ultrahigh pressure liquid chromatography (on line SPE-UHPLC), turbulent flow chromatography (TFC) and molecularly imprinted polymers (MIPs), were also addressed. The advantages and drawbacks of these methodologies applied to the fast and sensitive analyses of food and environmental samples are going to be discussed. PMID:22153282

Núñez, Oscar; Gallart-Ayala, Héctor; Martins, Claudia P B; Lucci, Paolo

2012-03-01

188

Application of Ion Pairing Chromatography to the Analysis of Inorganic Analytes: Review  

Microsoft Academic Search

The separation challenges that keep arising from the constantly evolving practical applications encountered in ion?pair chromatography (IPC) of inorganic analytes and inorganic elements containing compounds are reviewed. Emphasis is placed on species that are most important in the biochemical, biomedical areas or that are of concern in the environmental field. Examples will be given of the analysis and speciation of

Teresa Cecchi

2007-01-01

189

ANALYSIS OF FERRIC AND FERROUS IONS IN SOIL EXTRACTS BY ION CHROMATOGRAPHY  

EPA Science Inventory

A method using ion chromatography (IC) for the analysis of ferrous (Fe 2+) and ferric (Fe 3+) ions in soil extracts has been developed. This method uses an ion exchange column with detection at 520 nm after post-column derivatization. Selectivity is achieved by using an anionic...

190

Improved reversed-phase high performance liquid chromatography columns for biopharmaceutical analysis  

Microsoft Academic Search

Reversed-phase high performance liquid chromatography continues to grow in importance for the analysis of peptides and proteins in biomolecular and pharmaceutical research. The mobile-phase conditions for separation of proteins and peptides are essentially fixed. Most separations of these solutes are conducted with shallow gradients using aqueous buffers modified with acetonitrile. Therefore, changing selectivity in peptide and protein separations is often

R. D. Ricker; L. A. Sandoval; B. J. Permar; B. E. Boyes

1995-01-01

191

A multivariate statistical analysis approach to analyze gas chromatography-olfactometry data of tangerine hybrids  

Technology Transfer Automated Retrieval System (TEKTRAN)

Gas chromatography (GC) hyphenated with olfactometry (O) when a human subject smells the effluent of the GC is a useful technique to identify aroma activity of volatile compounds in a food. Many techniques have been developed, based on olfactory thresholds (CHARM analysis, AEDA), or based on psychop...

192

ANALYSIS OF CHLORINATED HERBICIDES BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY  

EPA Science Inventory

A method that uses high performance liquid chromatography/mass spectrometry (HPLC/MS) for the analysis of chlorinated phenoxyacid herbicides is described. uring method development different techniques were used to increase both the sensitivity and the specificity of thermospray H...

193

APPLICATION OF HIGH PERFORMANCE LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY TO ENVIRONMENTAL ANALYSIS  

EPA Science Inventory

High performance liquid chromatography (HPLC) coupled with nass spectronetry (MS) is described for the analysis of samples for environmental pollutants. uring the course of this work different techniques were used to increase both the sensitivity and specificity of HPLC/MS. hese ...

194

ANALYSIS OF NITRITE IN NO2 DIFFUSION TUBES USING ION CHROMATOGRAPHY  

EPA Science Inventory

An analytical method was developed for the analysis of the NO2 collected by a passive diffusion controlled atmospheric sampling device. The method measured the total amount of nitrite ion using ion chromatography. The precision obtained under field conditions, defined as twice th...

195

GAS CHROMATOGRAPHY/MATRIX ISOLATION - INFRARED SPECTROMETRY FOR AIR SAMPLE ANALYSIS  

EPA Science Inventory

This report describes the application of gas chromatography/matrix- solation infrared (GC/MI-IR) spectrometry to the analysIs of environmental air sample extracts. Samples that were analyzed include extracts from woodsmoke-impacted air, XAD-2 blanks, indoor air, and carpet sample...

196

Regioselective analysis of triacylglycerols by lipase hydrolysis  

Microsoft Academic Search

A modified procedure for the regiospecific analysis of triacylglycerols (TAG) with a 1,3-specific lipase is described. After\\u000a partial lipase hydrolysis of the triacylglycerol, the released free fatty acids (FFA) and 1,2(2,3)-diacylglycerols (DAG) were\\u000a isolated by thin-layer chromatography (TLC) and converted to fatty acid methyl esters (FAME). The FAME were analyzed by gas-liquid\\u000a chromatography (GLC). The 1,3-specific lipases used in this

Thomas A. Foglia; Edith J. Conkerton; Philip E. Sonnet

1995-01-01

197

Study of interfacial behavior in cocurrent gas-liquid flows  

SciTech Connect

We have examined the mechanism of formation of solitary waves on gas-liquid flows and found, that these form from existing periodic waves which have sufficiently large ({approximately}1.5 to 2 depending upon fluid properties) amplitude to liquid layer-thickness ratios. The exact process for the wave shape change is not understood but it does not seem to be related to the wave steepness (amplitude/wavelength) or to separation of gas flow over the waves. The observed confinement of solitary waves to low liquid Reynolds numbers results because the necessary large precursor waves do not form if the wave speed dispersion is too large or if the wavelength of the dominant waves is too short, as occurs for higher Re{sub L}. Measurements of interface tracings and calculations of power spectra and bispectra as a function of flow distance for conditions close to neutral stability reveal that the initially, linearly unstable mode is stabilized by formation of overtones which are linearly stable and can dissipate energy. As a result, a stable wave field can occur. Mode equations, which include quadratic nonlinearities, can model this process to the extent of producing some degree of quantitative predictions for the amplitudes of the wave modes. However, a complete picture of the wave field must include sidebands as well because these are observed for some flow conditions. 34 refs., 12 figs., 2 tabs.

McCready, M.J.

1990-01-01

198

Gas-Liquid Supersonic Cleaning and Cleaning Verification Spray System  

NASA Technical Reports Server (NTRS)

NASA Kennedy Space Center (KSC) recently entered into a nonexclusive license agreement with Applied Cryogenic Solutions (ACS), Inc. (Galveston, TX) to commercialize its Gas-Liquid Supersonic Cleaning and Cleaning Verification Spray System technology. This technology, developed by KSC, is a critical component of processes being developed and commercialized by ACS to replace current mechanical and chemical cleaning and descaling methods used by numerous industries. Pilot trials on heat exchanger tubing components have shown that the ACS technology provides for: Superior cleaning in a much shorter period of time. Lower energy and labor requirements for cleaning and de-scaling uper.ninih. Significant reductions in waste volumes by not using water, acidic or basic solutions, organic solvents, or nonvolatile solid abrasives as components in the cleaning process. Improved energy efficiency in post-cleaning heat exchanger operations. The ACS process consists of a spray head containing supersonic converging/diverging nozzles, a source of liquid gas; a novel, proprietary pumping system that permits pumping liquid nitrogen, liquid air, or supercritical carbon dioxide to pressures in the range of 20,000 to 60,000 psi; and various hoses, fittings, valves, and gauges. The size and number of nozzles can be varied so the system can be built in configurations ranging from small hand-held spray heads to large multinozzle cleaners. The system also can be used to verify if a part has been adequately cleaned.

Parrish, Lewis M.

2009-01-01

199

Headspace profiles of modified atmosphere packaged fresh red snapper (Lutjanus campechanus) by gas liquid chromatography  

E-print Network

* fe. ' ll 18 Rockfish (Sebastes miniatus) h Red hake, ch'nook salmon** Swordfish (~Xi hias gladius) '1"* 21"' Brown shrimp (Penaeus aztecus) Crayfish (Pacifastacus leniusculus) Killefer (1930) Stansby and Griffiths (1935) Coyne (1933...

Scorah, Craig Darrell Allen

1988-01-01

200

Quantitative Aging Pattern in Mouse Urine Vapor as Measured by Gas-Liquid Chromatography  

NASA Technical Reports Server (NTRS)

We have discovered a quantitative aging pattern in mouse urine vapor. The diagnostic power of the pattern has been found to be high. We hope that this pattern will eventually allow quantitative estimates of physiological age and some insight into the biochemistry of aging.

Robinson, Arthur B.; Dirren, Henri; Sheets, Alan; Miquel, Jaime; Lundgren, Paul R.

1975-01-01

201

Estimation of quizalofop ethyl residues in black gram (Vigna mungo L.) by gas liquid chromatography.  

PubMed

Quizalofop ethyl, a phenoxy propionate herbicide is used for post emergence control of annual and perennial grass weeds in broad-leaved crops in India. The experiments were designed to study the harvest time residues of quizalofop ethyl in black gram for two seasons. At harvest time, the residues of quizalofop ethyl on black gram seed, foliage and soil were found to be below the determination limit of 0.01 mg kg(-1) following a single application of the herbicide at 50 and 100 g a.i. ha(-1) for both the periods. Application of the herbicide is quite safe from a consumer and environmental point of view. PMID:24275886

Mandal, Kousik; Sahoo, Sanjay Kumar; Battu, R S; Singh, Balwinder

2014-01-01

202

Gas liquid chromatography of the hydroxy-, acetoxy-and oxo-stearic acid methyl esters  

Microsoft Academic Search

Carbon numbers have been determined for all the 17 isomeric methyl hydroxy- and acetoxystearates and for 15 of the 16 isomeric\\u000a methyl oxostearates using silicone SE-30, silicone QF-1, and ethylene glycol succinate (EGS) as liquid phases. The carbon\\u000a numbers of the isomers increase with increasing distance of the point of substitution from the carboxyl end of the fatty acid\\u000a chain

A. P. Tulloch

1964-01-01

203

Analysis of glycylsarcosine transport by lobster intestine using gas chromatography.  

PubMed

Gas chromatography was used to measure transepithelial transport of glycylsarcosine (Gly-Sar) by perfused lobster (Homarus americanus) intestine. Unidirectional and net fluxes of dipeptide across the tissue and luminal factors affecting their magnitude and direction were characterized by perfusing the lumen with the dipeptide and measuring its appearance in saline on the serosal side of the organ. Transmural transport of 10 mM Gly-Sar resulted in serosal accumulation of only the dipeptide; no appearance of corresponding monomeric amino acids glycine or sarcosine was observed. Carrier-mediated and diffusional transmural intestinal transport of Gly-Sar was estimated at 1-15 mM luminal concentrations and followed a curvilinear equation providing a K m = 0.44 ± 0.17 mM, a J max = 1.27 ± 0.12 nmol cm(-2) min(-1), and a diffusional coefficient = 0.026 ± 0.008 nmol cm(-2) min(-1) mM(-1). Unidirectional mucosal to serosal and serosal to mucosal fluxes of 10 mM Gly-Sar provided a significant (p < 0.05) net absorptive flux toward the serosa of 3.54 ± 0.77 nmol cm(-2) min(-1), further supporting carrier-mediated dipeptide transport across the gut. Alkaline (pH 8.5) luminal pH more than doubled transmural Gly-Sar transport as compared to acidic (pH 5.5) luminal pH, while luminal amino acid-metal chelates (e.g., Leu-Zn-Leu), and high concentrations of amino acids alone significantly (p < 0.001) reduced intestinal Gly-Sar transfer by inhibiting carrier transport of the dipeptide. Proposed mechanisms accounting for intestinal dipeptide transport and luminal factors affecting this process are discussed. PMID:25260349

Peterson, Maria L; Lane, Amy L; Ahearn, Gregory A

2015-01-01

204

NASA Li/CF(x) cell problem analysis: Anion exchange chromatography analysis  

NASA Technical Reports Server (NTRS)

An analysis was made of wiper samples used to wipe down lithium/chlorine fluorine battery components and production equipment. These components and equipment were potentially exposed to thionyl chloride vapors. In the presence of moisture, thionyl chloride decomposes to sulfur dioxide and hydrogen chloride. The wiper samples were analyzed for soluble chlorides and fluorides by anion exchange chromatography. During the examination of the test chromatographs, fluoride contamination was discovered in wiper samples from the test equipment. An analytical method to determine fluoride was developed. The first 3 extracts from the potentially exposed and clean wiper samples were tested, and the total fluoride from both groups determined. A comparison of the results from both groups was made to determine the extent of fluoride contamination.

Bytella, Joseph

1991-01-01

205

Enzyme Inhibition and Chromatographic Techniques: Comparative Studies and Application to Pesticide Residue Analysis  

Microsoft Academic Search

The development of enzyme inhibition techniques in relation to pesticide analysis is discussed, along with discussion of (a) principles of thin-layer chromatograph-enzyme inhibition (TLC-EI) technique, (b) general procedures of the technique, (c) the use of enzymes in combination with TLC and colorimetry, and (d) merits and limitations of the techniques. TLC-EI techniques and gas-liquid chromatography are compared based on sensitivity

C. E. Mendoza

1974-01-01

206

Quantitative analysis of coal-derived liquids by thin-layer chromatography with flame ionization detection  

Microsoft Academic Search

The use of column chromatographic procedures for the analysis of coal-derived liquids has a number of disadvantages. Most of these can be eliminated if thin-layer chromatography is used, in conjunction with a flame ionization detector. A typical application of TLC\\/FID techniques for the analysis of process oils from coal liquefaction and actual toluene extracts from coal liquefaction experiments is reported

Milan L. Selucky

1983-01-01

207

Analysis of barbiturates by micro-high-performance liquid chromatography with post-column photochemical derivatization.  

PubMed

This study attempts to combine the advantages of microcolumn high-performance liquid chromatography (micro-HPLC) with those of post-column photochemical derivatization in barbiturate analysis. Some barbiturates are photochemically unstable, leading to photoproducts that show maximum absorption at 270 nm and not the typical one at approximately 220 nm. For this purpose, a laboratory-built photoreactor has been developed to work with micro-HPLC instruments. Its performance is satisfactory in the forensic analysis of barbiturates. PMID:10722060

García-Borregón, P F; Lores, M; Cela, R

2000-02-18

208

Continuous gas/liquid–liquid/liquid flow synthesis of 4-fluoropyrazole derivatives by selective direct fluorination  

PubMed Central

Summary 4-Fluoropyrazole systems may be prepared by a single, sequential telescoped two-step continuous gas/liquid–liquid/liquid flow process from diketone, fluorine gas and hydrazine starting materials. PMID:21915207

Breen, Jessica R; Yufit, Dmitrii S; Howard, Judith A K; Fray, Jonathan; Patel, Bhairavi

2011-01-01

209

A Management Tool for Analyzing CHP Natural Gas Liquids Recovery System  

E-print Network

The objective of this research is to develop a management tool for analyzing combined heat and power (CHP) natural gas liquids (NGL) recovery systems. The methodology is developed around the central ideas of product recovery, possible recovery...

Olsen, C.; Kozman, T. A.; Lee, J.

2008-01-01

210

Gas–Liquid Flow and Mass Transfer in an Advanced-Flow Reactor  

E-print Network

Hydrodynamics and mass transfer of gas–liquid flow are explored under ambient conditions in an Advanced-Flow Reactor (AFR), an emerging commercial system designed for continuous manufacture. Carbon dioxide/water is the ...

Kulkarni, Amol A.

211

High resolution gas chromatography analysis of rice bran oil  

NASA Astrophysics Data System (ADS)

To assess the nutritional value and safety quality of rice bran oil (RBO) ,fatty acids of RBO from 15 species rice come from Hunan Province were analyzed by high resolution gas chromatography (HRGC). Crude RBOs were extracted by hexane 3-times using a solvent-to-rice bran ratio of 3:1 (w/w) at 40°C and composition of RBOs was analyzed by HRGC. The result showed that main fatty acids of 15 kinds of RBO include myristic acid (C14:0), palmitic acid (C16:0), palmitoleic acid (C16:1), stearic acid (C18:0), oleic acid (C18:1), linoleic acid (C18:2), linolenic acid (C18:3), arachidic acid (C20:0), arachidonic acid (C20:1). It is strange that arachidonic acid (C20:1) is not listed in Chinese standard of RBO (GB11192-2003), and it exists in our samples of RBO. The average value of linolenic acid in RBOs is 1.6304% (range from 1.2425% to 2.131%), and it showed higher level comparing with Chinese standard that linolenic acid is less than 1.0%. The average value of USFA and SFA are 76.81% (range 75.96% to 82.06% ) and 20.15% (range 13.72% to 23.06%) respectively, and USFA content is close to olive oil (83.75%), peanut oil (81.75%) and soybean oil (85.86%). USFA in Jingyou 13 RBO is the highest content. The ratio of USFA to SFA content is 4:1 (range from 3.32 to 5.98:1). The ratio of SFA: MUFA: PUFA of 15 RBOs is 1: 2.2: 1.8, and ?6/?3 ratio is 21.69 (range from16.54 to 27.28) and it is close to the 26:1 which is reported to be helpful to increase SOD activity. The oleic acid /linoleic acid ratio of 15 RBOs is 1.23:1 (rang from 1.04:1 to 1.42:1). Our data analyzed composition of RBOs from 15 species rice of China and will provide new evidence to revise RBO standard. It also helps us to assess nutritional value of RBOs and identify different RBOs from various species rice and places of origin.

Yu, Fengxiang; Lin, Qinlu; Chen, Xu; Wei, Xiaojun

212

Acoustic Probe for Solid-Gas-Liquid Suspension  

SciTech Connect

The primary objective of the research project during the first funding period was to develop an acoustic probe to measure volume percent solids in solid-liquid slurries in the presence of small amounts of gas bubbles. This problem was addressed because of the great need for a non-invasive, accurate and reliable method for solids monitoring in liquid slurries in the presence of radiolytically generated gases throughout the DOE complex. These measurements are necessary during mobilization of salts and sediments in tanks, transport of these slurries in transfer lines to processing facilities across a site, and, in some instances, during high level waste processing. Although acoustic probes have been commonly used for monitoring flows in single-phase fluids (McLeod, 1967), their application to monitor two-phase mixtures has not yet fully realized its potential. A number of investigators in recent years have therefore been involved in developing probes for measuring the volume fractions in liquid solid suspensions (Atkinson and Kytomaa, 1993; Greenwood et al., 1993; Martin et al., 1995) and in liquid-liquid suspensions (Bonnet and Tavlarides, 1987; Tavlarides and Bonnet, 1988, Yi and Tavlarides, 1990; Tsouris and Tavlarides, 1993, Tsouris et al., 1995). In particular, Atkinson and Kytomaa (1993) showed that the acoustic technique can be used to determine both the velocity and the volume fraction of solids while Martin et al. (1995) and Spelt et al. (1999) showed that the acoustic probe can also be used to obtain information on the size distribution of the particles. In a recent testing of in-line slurry monitors with radioactive slurries suspended with Pulsair Mixers (Hylton & Bayne, 1999), an acoustic probe did not compare well with other instruments most probably due to presence of entrained gases and improper acoustic frequency range of interrogation. The work of the investigators cited has established the potential of the acoustic probe for characterizing/monitoring two-phase flows in relatively ideal, well-characterized suspensions. Two major factors which we judge has prevented its wide-spread use in the processing industry, particularly for dilute suspensions, is careful selection of the frequency range for interrogation and quantification and removal of the noise introduced by bubbles from the acoustic signal obtained from the suspension. Our research during the first funding period to develop an acoustic probe for solid-gas liquid suspensions has resulted in a theory, supported by our experiments, to describe small amplitude dilute suspensions (Norato, 1999, Spelt et al., 1999, Spelt et al., 2001). The theory agrees well with experimental data of sound attenuation up to 45 {approx}01% suspensions of 0.11 and 77 micron radius polystyrene particles in water and 0.4 to 40 vol %, suspensions of 32 micron soda-lime glass particles in water. Also, analyses of our attenuation experiments for solid-gas liquid experiments suggest the theory can be applied to correct for signal interference due to the presence of bubbles over a selected frequency range to permit determination of the solid-liquid volume fraction. Further, we show experimentally that a reliable linear dependency of weight percent solids with attenuation is obtained for low weight fractions at high frequencies of interrogation where bubble interference is minimal. There was a collaborative effort during the first funding period with the Pacific Northwest National Laboratories in that Dr. Margaret Greenwood was a co-investigator on the project. Dr. Greenwood provided a high level of experimental knowledge and techniques on ultrasound propagation, measurement and data processing. During the second funding period the slurry test loop at Oak Ridge National Laboratories under the direction of Mr. Tom Hylton will be employed to demonstrate the measurement capabilities of the prototype acoustic monitor.

Tavlarides, L.L.; Sangani, Ashok

2003-09-14

213

INTERLABORATORY COMPARISON OF THERMOSPRAY AND PARTICLE BEAM LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY INTERFACES: EVALUATION OF A CHLORINATED PHENOXY ACID HERBICIDE LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY ANALYSIS METHOD  

EPA Science Inventory

Seven laboratories participated in an interlaboratory evaluation of a liquid chromatography/mass spectrometry (LC/MS) method for the analysis of 10 chlorinated phenoxy acid herbicides. The focus of this evaluation was to test the intercomparability of LC/MS data obtained from two...

214

The gas–liquid contacting effects on liquid dispersion in pilot scale upflow hydrotreaters  

Microsoft Academic Search

A model for the estimation of the extent of the non-ideal liquid flow from RTD data at operating conditions in small-scale hydrotreaters has been developed accounting for the gas oil evaporation and gas–liquid mass transfer. Non-ideal flow is described by the axial dispersion model. Gas–liquid phase mass transport and equilibrium are considered by simulating the petroleum gas oil fraction with

G. D. Bellos; K. P. Gotsis; P. A. Galtier; N. G. Papayannakos

2004-01-01

215

Gas and liquid chromatography with inductively coupled plasma mass spectrometry detection for environmental speciation analysis — advances and limitations  

Microsoft Academic Search

Recent advances in the coupling of gas chromatography (GC) and high performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometry (ICP MS) and their role in trace element speciation analysis of environmental materials are presented. The discussion is illustrated with three research examples concerning the following topics: (i) development and coupling of multicapillary microcolumn GC with ICP MS for

Joanna Szpunar; Shona McSheehy; Kasia Po?e?; Véronique Vacchina; Sandra Mounicou; Isaac Rodriguez; Ryszard ?obi?ski

2000-01-01

216

Analysis of anions in geological brines using ion chromatography  

SciTech Connect

Ion chromatographic procedures for the determination of the anions bromide, sulfate, nitrite, nitrate, phosphate, and iodide in brine samples have been developed and are described. The techniques have been applied to the analysis of natural brines, and geologic evaporites. Sample matrices varied over a range from 15,000 mg/L to 200,000 mg/L total halogens, nearly all of which is chloride. The analyzed anion concentrations ranged from less than 5 mg/L in the cases of nitrite, nitrate, and phosphate, to 20,000 mg/L in the case of sulfate. A technique for suppressing chloride and sulfate ions to facilitate the analysis of lower concentration anions is presented. Analysis times are typically less than 20 minutes for each procedure and the ion chromatographic results compare well with those obtained using more time consuming classical chemical analyses. 10 references, 14 figures.

Merrill, R.M.

1985-03-01

217

Two-dimensional correlation analysis of the reproducibility of high-performance liquid chromatography columns.  

PubMed

Two-dimensional (2D) correlation analysis is a well-established tool in spectroscopy. Despite its versatility in various measurement systems, 2D correlation has not yet become popular in separation science. 2D correlation is seldom used in chromatography; only a few a studies can be found on this topic and most of those publications report about gel chromatography. In the present study, 2D correlation analysis is applied to chromatograms. In this study, a simple method is built for studying the similarities and dissimilarities between a number of chromatograms. We present the applicability of the method by two examples, where the repeatability and reproducibility of the analytical and nonlinear measurements in HPLC are evaluated and demonstrated. In order to validate the results of 2D correlation analysis, they are compared to principal component analysis (PCA). We confirm the equivalence in the interpretation of the results obtained with the two methods of calculation. The results confirm that 2D correlation can be a successful chemometric tool in chromatography. PMID:25660524

Simon, József; Felinger, Attila

2015-03-01

218

Fast gas chromatography for pesticide residues analysis using analyte protectants  

Microsoft Academic Search

Fast GC–MS with narrow-bore columns combined with effective sample preparation technique (QuEChERS method) was used for evaluation of various calibration approaches in pesticide residues analysis. In order to compare the performance of analyte protectants (APs) with matrix-matched standards calibration curves of selected pesticides were searched in terms of linearity of responses, repeatability of measurements and reached limit of quantifications utilizing

Michal Kirchner; Renáta Húšková; Eva Matisová; Ján Mocák

2008-01-01

219

Quantitative analysis of food fatty acids by capillary gas chromatography  

Microsoft Academic Search

The superior efficiency of capillary columns is desirable for the gas chromatographic analysis of complex mixtures of fatty\\u000a acids, but there have been some reservations regarding quantitation and reproducibility. This paper discusses the use of wall-coated\\u000a glass capillary columns in a semiautomated system for the determination of food fatty acids. Glass columns coated with SP2340\\u000a were used for extended periods

H. T. Slover; E. Lanza

1979-01-01

220

Gas chromatography analysis of cellular fatty acids and neutral monosaccharides in the identification of lactobacilli.  

PubMed Central

Cellular fatty acids and monosaccharides in a group of 14 lactobacilli were analyzed by gas chromatography and the identity of the components was confirmed by gas chromatography-mass spectrometry. From the same bacterial sample, both monosaccharides and fatty acids were liberated by methanolysis, and in certain experiments, fatty acids alone were released by basic hydrolysis. The results indicate that basic hydrolysis gave more comprehensive information about the fatty acids, but the analysis of monosaccharides was found to be much more useful in distinguishing between different species of lactobacilli. The method described allowed differentiation of 11 of 14 Lactobacillus species, and even single colonies isolated from agar plates could be used for analysis without subculturing. PMID:3435147

Rizzo, A F; Korkeala, H; Mononen, I

1987-01-01

221

Solid phase microextraction coupled to liquid chromatography. Analysis of organosulphur compounds avoiding artifacts formation.  

PubMed

This work proposes the novel application of a microextraction technique, solid phase microextraction (SPME), coupled to liquid chromatography with UV detection (HPLC-UV) for the analysis of organosulfur compounds (OSCs) in garlic samples. Additionally, a comparative study of OSCs profiles obtained by SPME coupled to HPLC-UV and gas chromatography with flame photometric detector (GC-FPD), respectively; was carried out. This study provided complementary evidence about OSCs's lability and "artifacts" formation during the analytical process. Raw, cooked and distilled garlic samples were considered. The target analytes were diallyl disulphide (DADS), diallyl sulphide (DAS), diallyl trisulphide (DATS), allicin, 3-vinyl-4H-1,3-dithiin (3-VD), 2-vinyl-4H-1,2-dithiin (2-VD) and (E)- and (Z)-ajoene, which are the most important OSCs with biological activities present in raw and processed garlic. The coupling of SPME and HPLC showed to be reliable, fast, sensible and selective methodology for OSCs analysis. PMID:24679771

Locatelli, Daniela A; Altamirano, Jorgelina C; Luco, Juan M; Norlin, Rikard; Camargo, Alejandra B

2014-08-15

222

Regioselective analysis of the fatty acid composition of triacylglycerols with conventional high-performance liquid chromatography  

Microsoft Academic Search

A new method for regioselective analysis of triacyglycerols via conventional high-performance liquid chromatography (HPLC) has been developed. The method is simple and avoids the time-consuming\\u000a purification processes normally characteristics of regioselective analyses. The procedure utilizes an sn-1,3-specific lipase from Rhizopus arrhizus to deacylate the fatty acid residues located at the sn-1 and sn-3 positions of triacylglycerols. The fatty acid residues

Jose A. Arcos; Hugo S. Garcia; Charles G. Hill

2000-01-01

223

High-resolution analysis of catechol-type siderophores using polyamide thin layer chromatography  

Microsoft Academic Search

The iron-deficient culture supernatant of a soil bacterial strain identified as Erwinia sp. was analyzed using a new high-resolution polyamide thin layer chromatography (TLC) and a silica TLC. The results showed both TLC methods were very effective for separating simple catechol compounds such as 2,3-dihydroxybenzoic acid (2,3-DHBA) and catechol. However, in the analysis of more complicated catechol compounds or true

Xiaojun Xie; Jingguo Wang; Hongli Yuan

2006-01-01

224

Analysis of autoxidized fats by gas chromatography-mass spectrometry: III. Methyl linolenate  

Microsoft Academic Search

The gas chromatography-mass spectrometry (GC-MS) method developed in the preceding papers was extended to the analysis of\\u000a autoxidation products of methyl linolenate. Four isomeric hydroxy allylic trienes with a conjugated diene system were identified\\u000a after reduction of the linolenate hydroperoxides. All eight geometrictrans,cis- andtrans, trans-conjugated diene isomers of these hydroxy allylic compounds were identified and partially separated by GC of

E. N. Frankel; W. E. Neff; W. K. Rohwedder; B. P. S. Khambay; R. F. Garwood

1977-01-01

225

Analysis of the Morgan–Elson Chromogens by High-Performance Liquid Chromatography  

Microsoft Academic Search

The Morgan–Elson method for quantitativeN-acetylhexosamine analysis is a two-step procedure comprising alkali treatment of the sugar and subsequent condensation of the resulting chromogens withp-dimethylaminobenzaldehyde (Ehrlich's reagent) to yield a colored product. In the present investigation, the products formed in the first step of the procedure were analyzed by high-performance liquid chromatography (HPLC) on a reversed-phase (C18) column, which was eluted

Lennart Rodén; Hao Yu; Jin Jin; Göran Ekborg; Amy Estock; N. Rama Krishna; Peter Livant

1997-01-01

226

Blind Analysis of Denaturing High-Performance Liquid Chromatography as a Tool for Mutation Detection  

Microsoft Academic Search

Denaturing high-performance liquid chromatography (DHPLC) is a novel high-capacity technique for detecting new mutations. We have evaluated the sensitivity and specificity of this method in a blind analysis of exon H of the factor IX gene and exon 16 of the neurofibromatosis type 1 gene. Under a single set of conditions for each exon, 55\\/55 individuals carrying 48 unique mutations

Michael C. O'Donovan; Peter J. Oefner; Stacy C. Roberts; Jehannine Austin; Bastiaan Hoogendoorn; Carol Guy; Graham Speight; Meena Upadhyaya; Steve S. Sommer; Peter McGuffin

1998-01-01

227

Gas chromatography-mass spectrometry methods for structural analysis of fatty acids  

Microsoft Academic Search

Procedures for structural analysis of fatty acids are reviewed. The emphasis is on methods that involve gas chromatography-mass\\u000a spectrometry and, in particular, the use of picolinyl ester and dimethyloxazoline derivatives. These should be considered\\u000a as complementing each other, not simply as alternatives. However, additional derivatization procedures can be of value, including\\u000a hydrogenation and deuteration, and preparation of dimethyl disulfide and

William W. Christie

1998-01-01

228

Analysis of selected anticonvulsants by high performance liquid chromatography-tandem mass spectrometry.  

PubMed

A method for the analysis of the basic antiepileptic compounds felbamate, lamotrigine, carbamazepine, carbamazepine-10,11-epoxide, gabapentin, pregabalin, levetiracetam, and oxcarbazepine monohydroxy derivative (oxcarb MHD) in human plasma is described. This protocol incorporates a simplified sample preparation step followed by quantitative high performance chromatography-tandem mass spectrometry detection of commonly prescribed and monitored anticonvulsant drugs. Since polytherapy is common in epilepsy patients, use of a multiconstituent assay can improve laboratory efficiency and reduce required analytical time. PMID:22767120

Collins, Jennifer A; Janis, Gregory C

2012-01-01

229

Search on ruggedness of fast gas chromatography–mass spectrometry in pesticide residues analysis  

Microsoft Academic Search

In this study, suitability of fast gas chromatography–mass spectrometry (GC–MS) on a narrow-bore column with a programmed temperature vaporizer for the analysis of pesticide residues in non-fatty food was evaluated. The main objectives were ruggedness and stability of chromatographic system with regards to co-extractives injected. The chromatographic matrix induced response enhancement was found to be strongly dependent on the concentration

Michal Kirchner; Eva Matisová; Robert Otrekal; Andrea Hercegová; Jaap de Zeeuw

2005-01-01

230

Analysis of phenolic compounds in rhubarbs using liquid chromatography coupled with electrospray ionization mass spectrometry  

Microsoft Academic Search

Rhubarb is an important herbal medicine for the treatment of constipation, inflammation, and cancer. In this study, a facile\\u000a method based on liquid chromatography coupled with electrospray ionization tandem mass spectrometry has been established for\\u000a the analysis of bioactive phenolic compounds in rhubarbs. From six rhubarb species, official (Rheum officinale, R. palmatum, and R. tanguticum) and unofficial (R. franzenbachii, R.

Min Ye; Jian Han; Hubiao Chen; Junhua Zheng; Dean Guo

2007-01-01

231

On-line high performance liquid chromatography coupled with high resolution gas chromatography and mass spectrometry (HPLC-HRGC-MS) for the analysis of complex mixtures containing highly volatile compounds  

Microsoft Academic Search

A comparision between high resolution gas chromatography coupled with mass spectrometry (GC-MS) and an “on-line” high performance liquid chromatography, high resolution gas chromatography, mass spectrometry system (HPLC-HRGC-MS) is described for the analysis of complex mixtures. The latter allowed mass spectra with a purity and fit indices higher than those obtained from the GC-MS analysis of the whole sample to be

L. Mondello; P. Dugo; K. D. Bartle; B. Frere; G. Dugo

1994-01-01

232

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

SciTech Connect

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

Bernhardt, J.

1995-08-23

233

Venus lower atmospheric composition - Analysis by gas chromatography  

NASA Technical Reports Server (NTRS)

The first gas chromatographic analysis of the lower atmosphere of Venus is reported. Three atmospheric samples were analyzed. The third of these samples showed carbon dioxide (96.4 percent), molecular nitrogen (3.41 percent), water vapor (0.135 percent), molecular oxygen (69.3 ppm), argon (18.6 ppm), neon (4.31 ppm), and sulfur dioxide (186 ppm). The amounts of water vapor and sulfur dioxide detected are roughly compatible with the requirements of greenhouse models of the high surface temperature of Venus. The large positive gradient of sulfur dioxide, molecular oxygen, and water vapor from the cloud tops to their bottoms, as implied by Earth-based observations and these results, gives added support for the presence of major quantities of aqueous sulfuric acid in the clouds. A comparison of the inventory of inert gases found in the atmospheres of Venus, Earth, and Mars suggests that these components are due to outgassing from the planetary interiors.

Oyama, V. I.; Carle, G. C.; Woeller, F.; Pollack, J. B.

1979-01-01

234

Analysis of fluid inclusion leachates from quartz by ion chromatography  

NASA Astrophysics Data System (ADS)

20 chemical species have been detected and quantified in standard solutions using a Dionex 2000i-SP ion Chromatograph. These species are (minimum detection limits in ppb in injected sample follow each species; anions and cations listed in order of increasing retention time): F - (14), CH 3COO - (12), HCOO - (4), Cl - (6), NO -2 (9), Br -? (19), NO -3(16), HPO 2-4 (28), SO 2-4 (26), C 2O 2-4 oxalate (250), I - (20), Li + (0.5), Na +(0.7), NH +4 (0.6), K + (1.6), Rb + (3.5), Cs + (5.9), Mg 2+ (5), Ca 2+ (15) and Sr 2+ (100). A technique has been developed to clean fluid inclusion-bearing samples and obtain fluid inclusion leachates by hand crushing ~1-2 g samples under leaching solutions in an agate mortar and then separating the leachates by vacuum filtration. High-efficiency ion removal from the crushed sample is required since gas Chromatographic H 2O analyses of sample splits have been used to calculate species concentrations in fluid inclusions. Three separate crushes using different leaching solutions are required for a complete analysis. Cleaning procedures have been established for all components involved in the crush/leach procedure, and a system blank has been obtained by crush/leach analysis of heat-treated Brazilian quartz. The contact time between the leachate and the component (i.e., agate mortar) has been established as an important control on blank levels. The technique has been applied to three samples from the Tanco granitic pegmatite: the analyses show both a 'pegmatitic' and a possibly external fluid component. A combined, single sample, gas and ion Chromatographic procedure has been developed to link directly the fluid inclusion volatile and leachate data.

Der Channer, D. M.; Spooner, E. T. C.

1992-01-01

235

Evaluation of high-efficiency gas-liquid contactors for natural gas processing. Semi-annual report, April--September 1994  

SciTech Connect

Objective was to ensure reliable supply of high-quality natural gas by reducing the cost of treating subquality natural gas containing H{sub 2}O, CO{sub 2}, H{sub 2}S and/or trace quantities of other gaseous impurities by applying high-efficiency rotating and structured packing gas liquid contactors. The work included analysis of base case residence time, viscosity studies on low pressure rotary contactor system, and surface tension studies on the contactor.

NONE

1994-11-01

236

Venus lower atmospheric composition: analysis by gas chromatography.  

PubMed

The first gas chromatographic analysis of the lower atmosphere of Venus is reported. Three atmospheric samples were analyzed. The third of these samples showed carbon dioxide (96.4 percent), molecular nitrogen (3.41 percent), water vapor (0.135 percent), molecular oxygen [69.3 parts per million (ppm)], argon (18.6 ppm), neon (4.31 ppm), and sulfuir dioxide (186 ppm). The amounts of water vapor and sulfur dioxide detected are roughly compatible with the requirements of greenhouse models of the high surface temperature of Venus. The large positive gradient of sulfur dioxide, molecular oxygen, and water vapor from the clould tops to their bottoms, as implied by Earth-based observations and these resuilts, gives added support for the presence of major quantities of aqueous sulfuric acid in the clouds. A comparison of the inventory of inert gases found in the atmospheres of Venus, Earth, and Mars suggests that these components are due to outgassing from the planetary interiors. PMID:17833004

Oyama, V I; Carle, G C; Woeller, F; Pollack, J B

1979-02-23

237

EXTRACTION AND QUANTITATIVE ANALYSIS OF ELEMENTAL SULFUR FROM SULFIDE MINERAL SURFACES BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY. (R826189)  

EPA Science Inventory

A simple method for the quantitative determination of elemental sulfur on oxidized sulfide minerals is described. Extraction of elemental sulfur in perchloroethylene and subsequent analysis with high-performance liquid chromatography were used to ascertain the total elemental ...

238

Pesticide analysis in rose wines by micellar electrokinetic chromatography.  

PubMed

In this work, the determination of 11 pesticides (pirimicarb, metalaxyl, pyrimethanil, procymidone, nuarimol, azoxystrobin, tebufenozide, fenarimol, benalaxyl, penconazole, and tetradifon) in rose wines by micellar EKC (MEKC) using reversed electrode polarity stacking mode (REPSM) as online preconcentration strategy is described. The MEKC buffer consisted of 100 mM sodium tetraborate and 30 mM SDS at pH 8.5 with 6% v/v 1-propanol. A solid-phase microextraction (SPME) procedure using PDMS/divinylbenzene (PDMS/DVB) fibers was applied to extract the selected pesticides from the rose wine samples. The comparison between the calibration curves obtained from hydroalcoholic solutions (12% v/v ethanol) and from rose wines (matrix matched calibration) showed the existence of a strong matrix effect. Furthermore, a comparison with calibration curves obtained with white wine samples also showed significant differences for most of the analyzed pesticides. As a result, a matrix matched calibration was developed. Quantitative extraction from spiked wine samples was carried out in triplicate at two levels of concentration (range 0.18-6.00 mg/L). LODs between 0.040 and 0.929 mg/L were achieved, which are below the maximum residue limits (MRLs) established for wine grapes (except for pirimicarb) by the EU and Spain legislation as well as by the Codex Alimentarius. The established method - which is solvent free, cost effective, and fast - was also applied to the analysis of several homemade rose wine samples and a commercial one. Two of the selected pesticides were found in some of the analyzed samples. PMID:18027361

Ravelo-Pérez, Lidia M; Hernández-Borges, Javier; Borges-Miquel, Teresa M; Rodríguez-Delgado, Miguel Angel

2007-12-01

239

High pH reversed-phase chromatography with fraction concatenation for 2D proteomic analysis  

SciTech Connect

Orthogonal high-resolution separations are critical for attaining improved analytical dynamic ranges of proteome measurements. Concatenated high pH reversed phase liquid chromatography affords better separations than the strong cation exchange conventionally applied for two-dimensional shotgun proteomic analysis. For example, concatenated high pH reversed phase liquid chromatography increased identification coverage for peptides (e.g., by 1.8-fold) and proteins (e.g., by 1.6-fold) in shotgun proteomics analyses of a digested human protein sample. Additional advantages of concatenated high pH RPLC include improved protein sequence coverage, simplified sample processing, and reduced sample losses, making this an attractive first dimension separation strategy for two-dimensional proteomics analyses.

Yang, Feng; Shen, Yufeng; Camp, David G.; Smith, Richard D.

2012-04-01

240

Analysis of antimycin A by reversed-phase liquid chromatography/nuclear magnetic-resonance spectrometry  

USGS Publications Warehouse

A mixture of closely related streptomyces fermentation products, antimycin A, Is separated, and the components are identified by using reversed-phase high-performance liquid chromatography with directly linked 400-MHz proton nuclear magnetic resonance detection. Analyses of mixtures of three amino acids, alanine, glycine, and valine, are used to determine optimal measurement conditions. Sensitivity increases of as much as a factor of 3 are achieved, at the expense of some loss in chromatographic resolution, by use of an 80-?L NMR cell, Instead of a smaller 14-?L cell. Analysis of the antimycin A mixture, using the optimal analytical high performance liquid chromatography/nuclear magnetic resonance conditions, reveals it to consist of at least 10 closely related components.

Ha, Steven T.K.; Wilkins, Charles L.; Abidi, Sharon L.

1989-01-01

241

The mechanism for the formation of slug flow in vertical gas liquid two-phase flow  

NASA Astrophysics Data System (ADS)

This paper studies the mechanism for the formation of a slug flow in vertical gas-liquid two-phase flow. By analyzing void fraction waves and their instability, it is proved that the formation of a slug flow regime is due to the increase of void fraction waves, which causes the conglomeration of gas bubbles and the coalescence of bubble clusters in unstable bubbly flow. Experiments and analysis show that intense turbulence can restrain the formation of Taylor bubbles. Therefore, in a large diameter vertical pipe, a Taylor bubble can form under a condition of low continuous volume flux due to the action of void fraction waves. However, the coalescence effect of void fraction waves as it affects bubbles is suppressed in high continuous volume flux, and therefore, a slug flow regime cannot be observed in the evolution of flow patterns. Under a condition of high continuous volume flux ( VL=0.15 m/s) described in the paper, the flow pattern evolution is from cap bubbly flow to cap churn flow, and then gradually to churn flow with the increase of void fraction.

Sun, Baojiang; Wang, Ruihe; Zhao, Xinxin; Yan, Dachun

2002-12-01

242

Current density distribution on gas-liquid two-phase fluid flow in an air-wave type EHD pump  

Microsoft Academic Search

For gas-liquid two-phase flow systems of an air-wave type EHD pump, an influence of gas-liquid interface on current conduction was investigated in this experiment. The current density distribution along EHD induced liquid flow was obtained by using a plate electrode divided into 20 channels. The maximum current density appeared at a gas-liquid interface bounded to the plate electrode. It was

M. Kumeta; H. Matsunaga; R. Ohyama; A. Watson; J. S. Chang

2003-01-01

243

Analysis of brominated dioxins and furans by high resolution gas chromatography/high resolution mass spectrometry.  

PubMed

This article reviews the available literature on the analysis of brominated dibenzo-p dioxins and furans (PBDD/Fs) by high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). Sample extraction and clean up, injection techniques, chromatographic separation, labelled standards and QA/QC works are discussed. Furthermore, full separation of PBDD/Fs from polybrominated diphenyl ethers (PBDEs) during clean up and control of possible chromatographic interference of PBDEs during instrumental analysis as well as possible actions to further enhance the quality of published data are discussed in detail. PMID:18954873

Hagberg, Jessika

2009-01-16

244

Evaluation of vermicompost maturity using scanning electron microscopy and paper chromatography analysis.  

PubMed

Vermicompost was produced from flower waste inoculated with biofertilizers using the earthworm Eisenia fetida. Principal component analysis (PCA) and cluster analysis (CA) were carried out on the basis of physicochemical parameters of vermicomposted samples. From the results of the PCA and CA, it was possible to classify two different groups of vermicompost samples in the following categories: E2 and E5; and E1, E3, E4, and control. Scanning electron microscopy and biodynamic circular paper chromatography analysis were used to investigate the changes in surface morphology and functional groups in the control and vermicompost products. SEM analysis of E1-E5 shows more fragment and pores than the control. Chromatographic analysis of vermicompost indicated the mature condition of the compost materials. PMID:24634991

Senthil Kumar, D; Satheesh Kumar, P; Rajendran, N M; Uthaya Kumar, V; Anbuganapathi, G

2014-04-01

245

Practice on high performance liquid chromatography. Applications, equipment, and quantitative analysis  

SciTech Connect

The title of this book suggests yet another general text on the principles and practice of HPLC-of which there are at least a dozen currently available. This is not the case, however. Instead, the editor has assembled a series of more specialized chapters addressed to the experienced chromatographer. That is, it is assumed that the reader has already been exposed to a more general and basic book on HPLC. Thus, there is no general discussion of the principles of separation, extracolumn effects, how an HPLC procedure is developed, column packings and techniques for reversed-phase HPLC, etc. The first five chapters of the book deal with equipment, quantitative analysis, preparative HPLC, column switching, and sample pretreatment. This paper of the book contains useful material not often seen in other books or review articles. The next two chapters deal with liquid-liquid and ion pair chromatography but ignore reversed-phase, normal-phase, and ion exchange chromatography. The final eight chapters deal with applications in different areas: inorganic samples, forensic chemistry, lipids, nucleic acid metabolites, drugs of pharmaceutical interest, amino acids, proteins, and coal and oil products. To summarize, this book is something between a basic text on HPLC and a review series such as Giddings's Advances in Chromatography. Whereas every practicing chromatographer should have a book of the first kind, libraries are the usual customers for the second kind. The author found this book useful in a variety of ways and so should many other reader.

Engelhardt, H. (ed.)

1986-01-01

246

Gas-liquid annular flow in vertical circular tubes with liquid penetrated in nucleus  

NASA Astrophysics Data System (ADS)

A semi-analytical model is proposed for fully developed upward gas-liquid annular flow inside vertical circular tubes, by utilizing well known turbulence algebraic models for single-phase flows, within both streams, combined with empirical correlations for the gas-liquid interface friction factor. Direct integration of the associated momentum equations provide the velocity distribution for each phase, as well as overall quantities of practical interest such as liquid film thickness and pressure gradient. The effects of liquid droplets entrainment in the gas is specialized empirical correlations. Extensive comparisons with experimental results are made in order to demonstrate the consistency of the proposed model.

Nogueira, E.; Brum, N. C. L.; Cotta, R. M.

1990-05-01

247

Gas-liquid mass transfer in a three-phase fluidized bed containing low density particles  

SciTech Connect

Gas-liquid mass-transfer behavior in a three-phase fluidized bed containing particles with properties comparable to those of bioparticles used in biological processes was examined. The volumetric gas-liquid mass-transfer coefficients, k{sub L}a, decrease with increasing solid concentration and with increasing terminal velocity of particles. An increase in the liquid velocity significantly increases k{sub L}a, but only slightly increases the gas holdup, thus suggesting a significant liquid velocity effect on k{sub L}.

Tang, W.T. (Shell Development Co., Houston, TX (USA)); Fan, L.S. (Ohio State Univ., Columbus, OH (USA). Dept. of Chemical Engineering)

1990-01-01

248

In situ search for organics by gas chromatography analysis: new derivatization / thermochemolysis approach  

NASA Astrophysics Data System (ADS)

Many organic molecules are present in interstellar clouds and might be carried to the early Earth by comets and meteorites during the heavy bombardment phase in the first few hundred million years of the solar system. It has been suggested that extraterrestrial organic material may well represent an important part of the organic material available for the origin of life. Until samples, brought by future space missions, are available on Earth, in situ measurements are one of the way to get unaltered and non-contaminated samples for analysis. The analytical technique has to be robust, sensitive and non-specific due to the large scope of targets molecules. The only currently flight qualified technique of analysis of organic molecules in space is gas chromatography (Viking, Cassini-Huygens, SAM-MSL, COSAC-Rosetta). The main objective of this work is to present a new approach with multi step analysis using derivatisation and thermochemolysis reagents for a one pot in situ analysis of volatile and refractory organics in surface or sub-surface samples (Mars, comets).Indeed, no single technology enables to identify all organic compounds because naturally occurring molecules have different polarities, molecular weights, being extractible or recalcitrant, bonded trapped or adsorbed on minerals. Thus, we propose to wider the scope of chemical reagent already validated for in situ wet chemistry such as MTBSTFA (Rodier et al. 2001, 2002), DMF-DMA (Rodier et al. 2002), or TMAH (Rodier et al, 2005, Geffroy-Rodier et al; 2009) to analyze enantiomers of amino acids, carbohydrates and lipids in a one pot several steps sub system using a multi reagent and multi step approach. Thus using a new derivatizing agent, we successfully identified twenty one amino acids including twelve of the twenty proteinic amino acids without inhibiting following multi step thermochemolysis. *Geffroy-Rodier C, Grasset L, Sternberg R. Buch A. Amblès A. (2009) Thermochemolysis in search for organics in extraterrestrial environments, Journal of Applied Pyrolysis 85: 454-459. *Rodier C, Sternberg R, Raulin F, Vidal-Madjar C (2001). In situ detection of organic molecules in extraterrestrial environment by gas chromatography / mass spectrometry. Journal of Chromatography A 915: 199-207. *Rodier C, Laurent C, Szopa C. Sternberg R, Raulin F (2002) Chirality and the origin of life: in situ enantiomeric separation for future space missions, Chirality 14: 527-532. *Rodier C. Sternberg R, Szopa C, Buch A, Cabane M and Raulin F (2005) Search for organics in extraterrestrial environments by in situ gas chromatography analysis. Advances in Space Research 36: 195-200. This work has been funded by CNES

Geffroy, Claude; Buch, Arnaud; David, Marc; Aissat, Lyes; El Mufleh, Amel; Papot, S.; Sternberg, Robert

249

Statistical Analysis of the Collaborative Study in Support of the Official Method AOCS Ce 1i-07: Determination of Saturated, cis -Monounsaturated and cis Polyunsaturated Fatty Acids in Marine and Other Oils Containing Long Chain Polyunsaturated Fatty Acids by Capillary GLC  

Microsoft Academic Search

Analysis was done of the statistical results obtained by following recommended AOCS Collaborative Study Procedure M-86 to\\u000a evaluate the performance of Official Method AOCS Ce 1i-07, which provides a gas–liquid chromatography (GLC) procedure for\\u000a the determination of the fatty acid composition of oils containing long chain polyunsaturated fatty acids (PUFAs). The method\\u000a obtains relative between-lab reproducibility (%RSDR) values on the

Sean A. Smith; Steven L. Hansen

2008-01-01

250

Simple, specific analysis of organophosphorus and carbamate pesticides in sediments using column extraction and gas chromatography  

USGS Publications Warehouse

A simple, specific procedure was developed for the analysis of organophosphorus and carbamate pesticides in sediment. The wet soil was mixed with anhydrous sodium sulfate to bind water and the residues were column extracted in acetone:methylene chloride (1:l,v/v). Coextracted water was removed by additional sodium sulfate packed below the sample mixture. The eluate was concentrated and analyzed directly by capillary gas chromatography using phosphorus and nitrogen specific detectors. Recoveries averaged 93 % for sediments extracted shortly after spiking, but decreased significantly as the samples aged.

Belisle, A.A.; Swineford, D.M.

1988-01-01

251

Microwave-assisted derivatization procedures for gas chromatography\\/mass spectrometry analysis  

Microsoft Academic Search

In this review, published applications of microwave-assisted derivatization procedures for gas chromatography\\/mass spectrometry\\u000a (GC\\/MS) are summarized. Among the broad range of analytical techniques available, GC\\/MS is still the method of choice for\\u000a most high-throughput screening procedures in forensic\\/clinical toxicology, doping control and food and environmental analysis.\\u000a Despite the many advantages of the GC\\/MS method, time-consuming derivatization steps are often required

Sandra L. Söderholm; Markus Damm; C. Oliver Kappe

2010-01-01

252

Fluorescence analysis of p-hydroxymethamphetamine in urine by thin-layer chromatography.  

PubMed

A highly-sensitive analytical method for the detection of p-hydroxymethamphetamine (pOHMA) in urine is presented. The proposed method combines liquid-liquid extraction with acetonitrile and solid-phase extraction by thin-layer chromatography (TLC) with oxidation using potassium hexacyanoferrate(III) and sodium hydroxide to detect the fluorophor of pOHMA. The detection limit for pOHMA is 10 ng (n = 3). The analysis of pOHMA in forensic samples is successfully performed, without interference from endogenous fluorophors, yielding concentrations in the appropriate range for methamphetamine abusers. PMID:16363483

Kato, Noriyuki; Kubo, Hiroaki; Homma, Hiroshi

2005-09-01

253

A Laboratory Experiment in Pharmaceutical Analysis: Analysis of Diazepam Tablets by High Pressure Liquid Chromatography  

ERIC Educational Resources Information Center

The experiment described was developed for the third-year course in inorganic and analytical pharmaceutical chemistry to provide students with "hands-on" experience with high pressure liquid chromatography. Assay procedures are given along with experimental parameters and student results. (LBH)

Bailey, Leonard

1978-01-01

254

Enantiomeric analysis of limonene and carvone by direct introduction of aromatic plants into multidimensional gas chromatography.  

PubMed

Analysis of chiral compounds in complex mixtures is achieved by multidimensional gas chromatography using heptakis-(2,3,6-tri-O-methyl)-?-cyclodextrin stationary phase as the main column of the system to separate specific selected cuts containing components unresolved in the first dimension. The proposed procedure allows rapid analysis of both solid and liquid matrices by direct introduction, into the programmed temperature vaporizer (PTV) of a gas chromatograph, of either the plant material or the essential oil, respectively. A comparison between enantiomeric excesses data obtained, from plant leaves (or plant seeds) and the corresponding essential oils, by direct injection (i.e., without sample pretreatment or concentration step) into the multidimensional system is also included. Reported data demonstrate that no racemization occurs during analysis as identical enantiomeric excesses are obtained in both cases for specific chiral compounds. PMID:23598101

Barba, C; Toledano, R M; Santa-María, G; Herraiz, M; Martínez, R M

2013-03-15

255

40 CFR Table Mm-1 to Subpart Mm of... - Default Factors for Petroleum Products and Natural Gas Liquids 1 2  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Default Factors for Petroleum Products and Natural Gas Liquids 1 2...GREENHOUSE GAS REPORTING Suppliers of Petroleum Products Pt. 98, Subpt. MM, Table...MM of Part 98—Default Factors for Petroleum Products and Natural Gas Liquids 1...

2011-07-01

256

40 CFR Table Mm-1 to Subpart Mm of... - Default Factors for Petroleum Products and Natural Gas Liquids 1 2  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Default Factors for Petroleum Products and Natural Gas Liquids 1 2...GREENHOUSE GAS REPORTING Suppliers of Petroleum Products Pt. 98, Subpt. MM, Table...MM of Part 98—Default Factors for Petroleum Products and Natural Gas Liquids 1...

2012-07-01

257

40 CFR Table Mm-1 to Subpart Mm of... - Default Factors for Petroleum Products and Natural Gas Liquids 1 2  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Default Factors for Petroleum Products and Natural Gas Liquids 1 2...GREENHOUSE GAS REPORTING Suppliers of Petroleum Products Pt. 98, Subpt. MM, Table...MM of Part 98—Default Factors for Petroleum Products and Natural Gas Liquids 1...

2013-07-01

258

40 CFR Table Mm-1 to Subpart Mm of... - Default Factors for Petroleum Products and Natural Gas Liquids 1 2  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Default Factors for Petroleum Products and Natural Gas Liquids 1 2...GREENHOUSE GAS REPORTING Suppliers of Petroleum Products Pt. 98, Subpt. MM, Table...MM of Part 98—Default Factors for Petroleum Products and Natural Gas Liquids 1...

2014-07-01

259

Study on the gas-liquid interface and polymer melt front in gas-assisted injection molding  

SciTech Connect

The algorithms are developed to predict the gas-liquid interface in gas-assisted injection molding. The simulation of two-dimensional, transient, non-isothermal and high viscous flow between two parallel plates with the generalized Newtonian fluid is presented in detail. The model takes into account the effects of the gas-liquid interface and polymer melt front.

Shen, Y.K. [Chien Hsin Coll. of Technology and Commerce, Chung-Li (Taiwan, Province of China). Dept. of Mechanical Engineering] [Chien Hsin Coll. of Technology and Commerce, Chung-Li (Taiwan, Province of China). Dept. of Mechanical Engineering

1997-03-01

260

Multiresidue analysis of 30 organochlorine pesticides in milk and milk powder by gel permeation chromatography-solid phase extraction-gas chromatography-tandem mass spectrometry.  

PubMed

A method for simultaneous determination of the 30 organochlorine pesticides (OCP) in milk and milk powder samples has been developed. Prior to the gas chromatography-tandem mass spectrometric analysis, the residual OCP in samples were extracted with n-hexane and acetone mixture (1/1, vol/vol) and cleaned up by gel permeation chromatography and solid phase extraction. Selected reaction monitoring mode was used for gas chromatography-tandem mass spectrometric data acquisition to identify and quantify the OCP. To avoid the matrix effects, matrix-matched calibration solutions ranging from 2 to 50 ng/mL were used to record the calibration curve. Limits of quantification of all OCP were 0.8 ?g/kg. With the exception of endrin, limits of quantification are signi?cantly lower than maximum residue limits set by the European Union and China. The average recoveries were in the range of 70.1 to 114.7% at 3 spiked concentration levels (0.8, 2.0, and 10.0 ?g/kg) with residual standard deviation lower than 12.9%. The developed method was successfully applied to analyze the OCP in commercial milk products. PMID:25087035

Zheng, Guocan; Han, Chao; Liu, Yi; Wang, Jing; Zhu, Meiwen; Wang, Chengjun; Shen, Yan

2014-10-01

261

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

SciTech Connect

Thermal decomposition of poly dimethyl siloxane compounds, Sylgard{reg_sign} 184 and 186, were examined using thermal desorption coupled gas chromatography-mass spectrometry (TD/GC-MS) and multivariate analysis. This work describes a method of producing multiway data using a stepped thermal desorption. The technique involves sequentially heating a sample of the material of interest with subsequent analysis in a commercial GC/MS system. The decomposition chromatograms were analyzed using multivariate analysis tools including principal component analysis (PCA), factor rotation employing the varimax criterion, and multivariate curve resolution. The results of the analysis show seven components related to offgassing of various fractions of siloxanes that vary as a function of temperature. Thermal desorption coupled with gas chromatography-mass spectrometry (TD/GC-MS) is a powerful analytical technique for analyzing chemical mixtures. It has great potential in numerous analytic areas including materials analysis, sports medicine, in the detection of designer drugs; and biological research for metabolomics. Data analysis is complicated, far from automated and can result in high false positive or false negative rates. We have demonstrated a step-wise TD/GC-MS technique that removes more volatile compounds from a sample before extracting the less volatile compounds. This creates an additional dimension of separation before the GC column, while simultaneously generating three-way data. Sandia's proven multivariate analysis methods, when applied to these data, have several advantages over current commercial options. It also has demonstrated potential for success in finding and enabling identification of trace compounds. Several challenges remain, however, including understanding the sources of noise in the data, outlier detection, improving the data pretreatment and analysis methods, developing a software tool for ease of use by the chemist, and demonstrating our belief that this multivariate analysis will enable superior differentiation capabilities. In addition, noise and system artifacts challenge the analysis of GC-MS data collected on lower cost equipment, ubiquitous in commercial laboratories. This research has the potential to affect many areas of analytical chemistry including materials analysis, medical testing, and environmental surveillance. It could also provide a method to measure adsorption parameters for chemical interactions on various surfaces by measuring desorption as a function of temperature for mixtures. We have presented results of a novel method for examining offgas products of a common PDMS material. Our method involves utilizing a stepped TD/GC-MS data acquisition scheme that may be almost totally automated, coupled with multivariate analysis schemes. This method of data generation and analysis can be applied to a number of materials aging and thermal degradation studies.

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

2010-09-01

262

Pulsed Barrier Discharge in Gas-Liquid Two-Phase Flow for Water Treatment  

Microsoft Academic Search

Summary form only given. Pulsed barrier discharge is generated in a gas-liquid two-phase flow for decomposing persistent substances in water. This new method is proposed to extend the interfacial area between the nonthermal plasma and the treat water for efficient decomposition of persistent materials. Acetic acid solution as a persistent substance is filled in a plasma reactor that consists of

K. Yasuoka; H. Katayama; S. Ishii

2007-01-01

263

Extremely fast gas/liquid reactions in flow microreactors: carboxylation of short-lived organolithiums.  

PubMed

Carboxylation of short-lived organolithiums bearing electrophilic functional groups such as nitro, cyano, and alkoxycarbonyl groups with CO2 to give carboxylic acids and active esters was accomplished in a flow microreactor system. The successful reactions indicate that gas/liquid mass transfer and the subsequent chemical reaction with CO2 are extremely fast. PMID:24863501

Nagaki, Aiichiro; Takahashi, Yusuke; Yoshida, Jun-ichi

2014-06-23

264

Formation of a drop size distribution in a gas-liquid stream  

Microsoft Academic Search

Holography was used to study the formation of drop size distribution in dispersive annular gas-liquid flows; experiments were performed using water, ethyl alcohol, and glycerine solution. Attention was paid to the deformation of the wave-surface of the liquid film on the wall (of the test channel) with consideration of critical deformations leading to destruction of the film. The size distribution

V. N. Bykov; M. E. Lavrentev

1976-01-01

265

Experimental studies on insulation properties of gas-liquid two-phase flow system  

Microsoft Academic Search

With the change of the cooling method, the configuration of insulation in generator is changed. Measures have been took to analyses and optimize the configuration of insulation. In this paper, investigation on new coolant insulation, which is considered to be a possible replacement of main insulation of stator in generator, is carried out. The insulation properties of gas-liquid two-phase flows

P. Yan; L. X. Yao; Y. X. Zhou; G. S. Sun

2002-01-01

266

Flow Patterns, Void Fraction and Pressure Drop in Gas-Liquid Two  

E-print Network

#12;Chapter 4 Flow Patterns, Void Fraction and Pressure Drop in Gas-Liquid Two Phase Flow an insightful discussion on flow patterns, void fraction and phenomenon of two phase frictional pressure drop on the void fraction and two phase pressure drop. Additionally, a brief overview of the void fraction, its

Ghajar, Afshin J.

267

Research on Gas-liquid Flow Rate Optimization in Foam Drilling  

NASA Astrophysics Data System (ADS)

With the advantages of less gas consumption, higher carrying rocks ability, lower leakage and higher penetration rate, foam drilling is widely used today in petroleum industry. In the process of foam underbalanced drilling, the mixture of gas, liquid and cuttings flows upwards through the annular, so it is a typical gas-liquid-solid multi-phase flow. In order to protect the reservoir and avoid borehole wall collapsing during foam drilling, it is crucial to ensure that the bottom hole pressure is lower than the formation pressure and higher than the formation collapse pressure, and in the mean time, foam drilling fluid in the whole wellbore should be in the best foam quality stage in order to have sufficient capacity to carry cuttings. In this paper, main relations between bottom hole pressure and gas-liquid injecting rate are analyzed with the underbalanced multiphase flow models. And in order to obtain precise flow pattern and flow pressure, the whole well bore is spatial meshed and iterative method is used. So, a convenient safety window expressed by gas-liquid injecting rate is obtained instead of that by bottom hole pressure. Finally, a foam drilling example from a block in Yemen is presented; the drilling results show that this method is reliable and practical.

Gao, B. K.; Sun, D. G.; Jia, Z. G.; Huang, Z. Q.

2010-03-01

268

Plasmachemical oxidation processes in a hybrid gas liquid electrical discharge reactor  

Microsoft Academic Search

Oxidation processes induced in water by pulsed electrical discharges generated simultaneously in the gas phase in close proximity to the water surface and directly in the liquid were investigated in a hybrid series gas-liquid electrical discharge reactor. The mechanism of phenol degradation was studied through its dependence on the gas phase and liquid phase compositions using pure argon and oxygen

Petr Lukes; Bruce R. Locke

2005-01-01

269

Two-dimensional two-phase gas-liquid flow. I - Flow patterns  

NASA Astrophysics Data System (ADS)

Two-dimensional gas-liquid flows can appear in various structures such as petroleum or geothermal fissured reservoirs and heat transfer devices. The present work describes the flow patterns observed when the surface velocities of the gas and liquid phases as well as the inclination vary. Flow patterns for horizontal flow are presented.

Kouame, Seraphin; Piquemal, Jean; Bories, Serge

1991-08-01

270

Schlieren visualization of natural convection in binary gas–liquid systems  

Microsoft Academic Search

Natural convection in 23 gas–liquid systems in a quiescent cell is visualized by Schlieren techniques. CO2 absorption and desorption in 16 organic solvents and MEA aqueous solutions, and evaporation and condensation in six binary liquid mixtures are studied. Experimental data on densities and surface tensions of mixtures under investigation is presented. An empirical linear relationship between the density effect of

Andrei Okhotsimskii; Mitsunori Hozawa

1998-01-01

271

Pesticide analysis by gas chromatography with a novel atomic emission detector.  

PubMed

An atomic emission detector, consisting of a microwave-induced helium plasma and atomic emission spectrometer, has been used for the gas chromatographic analysis of pesticides. In principle, it is possible to detect any element in the periodic table (except helium) which can elute from a gas chromatograph. Detection limits for C, H, D, N, O, Br, Cl, F, S, Si, P, Sn and Hg were found to range from 0.1 to 75 pg/s with selectivities over carbon of 5000 or more. The gas chromatography-atomic emission detection system has been used for the detection and elemental characterization of 27 different pesticides by obtaining element-specific chromatograms for C, H, N, O, Br, Cl, F, P and S. By performing quantitative analysis for each element, it was possible to calculate the approximate empirical formulas for 20 different herbicides in two different mixtures. An extract from an apple doped with three pesticides was analyzed by gas chromatography-atomic emission detection. PMID:2250048

Wylie, P L; Oguchi, R

1990-09-26

272

Keto acid profiling analysis as ethoxime/tert-butyldimethylsilyl derivatives by gas chromatography-mass spectrometry.  

PubMed

Organic acids, including keto acids, are key intermediates of central pathways in cellular metabolism. In this study, a comprehensive and reliable method was developed and optimized for the simultaneous measurement of 17 keto acids in various biological samples. The keto acids were converted to solvent extractable forms by ethoximation followed by tert-butyldimethylsilylation for direct analysis by gas chromatography-mass spectrometry in selected ion monitoring mode. The proposed method was precise (0.05-8.3, % RSD) and accurate (-10.5 to 5.3, % RE) with low limit of detection (0.01-0.5ng/mL) and good linearity (r>0.995) in the range of 0.01-5.0?g/mL. This was suitable for profiling analysis of targeted keto acids in human plasma, urine and rat brain tissue. PMID:23270938

Nguyen, Duc-Toan; Lee, Gwang; Paik, Man-Jeong

2013-01-15

273

Carbohydrate Analysis of Bacterial Polysaccharides by High-pH Anion-Exchange Chromatography and Online  

E-print Network

is universally applicable. High-resolu- tion gas chromatography of volatile derivatives with chiral reagents has been done in several different ways, the most common being gas­liquid chromatography-2608. E-mail: bush@umbc.edu or lacourse@umbc.edu. 2 Abbreviations used: GLC, gas­liquid chromatography; CD

Bush, C. Allen

274

Complementary fragmentation pattern analysis by gas chromatography-mass spectrometry and liquid chromatography tandem mass spectrometry confirmed the precious lignan content of Cirsium weeds.  

PubMed

In this paper, as novelties to the field, it is confirmed at first, that the fruits of Cirsium species, regarded as injurious weeds, do contain lignans, two, different butyrolactone-type glycoside/aglycone pairs: the well known arctiin/arctigenin and the particularly rare tracheloside/trachelogenin species. These experiences were supported by gas chromatography-mass spectrometry (GC-MS), by liquid chromatography tandem mass spectrometry (LC-MS/(MS)) and by nuclear magnetic resonance (NMR) spectroscopy. The study reflects the powerful impact of the complementary chromatographic mass fragmentation evidences resulting in the identification and quantification, the extremely rare, with on line technique not yet identified and described, tracheloside/trachelogenin pair lignans, without authentic standard compounds. Fragmentation pattern analysis of the trimethylsilyl (TMS) derivative of trachelogenin, based on GC-MS, via two different fragmentation pathways confirmed the detailed structure of the trachelogenin molecule. The complementary chromatographic evidences have been unambiguously confirmed, by (1)H and (13)C NMR analysis of trachelogenin, isolated by preparative chromatography. Identification and quantification of the fruit extracts of four Cirsium (C.) species (C. arvense, C. canum, C. oleraceum, and C. palustre), revealed that (i) all four species do accumulate the tracheloside/trachelogenin or the arctiin/arctigenin butyrolactone-type glycoside/aglycone pairs, (ii) the overwhelming part of lignans are present as glycosides (tracheloside 9.1-14.5 mg/g, arctiin 28.6-39.3 mg/g, expressed on dry fruit basis), (iii) their acidic and enzymatic hydrolyses to the corresponding aglycones, to trachelogenin and arctigenin are fast and quantitative and (iv) the many-sided beneficial trachelogenin and arctigenin can be prepared separately, without impurities, excellent for medicinal purposes. PMID:20813375

Boldizsár, I; Kraszni, M; Tóth, F; Noszál, B; Molnár-Perl, I

2010-10-01

275

Influence of soil type and extraction conditions on perchlorate analysis by ion chromatography.  

PubMed

Perchlorate is a stable anion that has been introduced into the environment through activities related to its production and use as a solid rocket propellant. Perchlorate is thought to transport through soils without being adsorbed; thus, for determination of perchlorate in soil, samples are typically extracted with water prior to analysis. The completeness of extraction depends on perchlorate existing as a free ion within the soil matrix. In this study, perchlorate extraction efficiency was evaluated with five soil types under two different oxygen states. For each soil, 30% (w/w) slurries were prepared and equilibrated under either oxic or anoxic conditions prior to spiking with a stock solution of sodium perchlorate, and the slurries were then maintained for 1-week or 1-month. At the end of the exposure, slurries were centrifuged and separated into aqueous and soil phases. After phase separation, the soil was washed first with deionized water and then with 50mM NaOH, producing second and third aqueous phases, respectively. Perchlorate concentrations in the three aqueous phases were determined using ion chromatography. The results obtained from this study suggest that matrix interference and signal suppression due to high conductivity have greater effects upon observed perchlorate concentrations by ion chromatography than does perchlorate interaction with soil. Thus, a single water extraction is sufficient for quantitative determination of perchlorate in soil. PMID:17092539

MacMillan, Denise K; Dalton, Shana R; Bednar, Anthony J; Waisner, Scott A; Arora, Prem N

2007-02-01

276

Quantitative Analysis of Tetramethylenedisulfotetramine ("Tetramine") Spiked into Beverages by Liquid Chromatography Tandem Mass Spectrometry with Validation by Gas Chromatography Mass Spectrometry  

SciTech Connect

Tetramethylenedisulfotetramine, commonly known as tetramine, is a highly neurotoxic rodenticide (human oral LD{sub 50} = 0.1 mg/kg) used in hundreds of deliberate food poisoning events in China. Here we describe a method for quantitation of tetramine spiked into beverages, including milk, juice, tea, cola, and water and cleaned up by C8 solid phase extraction and liquid-liquid extraction. Quantitation by high performance liquid chromatography tandem mass spectrometry (LC/MS/MS) was based upon fragmentation of m/z 347 to m/z 268. The method was validated by gas chromatography mass spectrometry (GC/MS) operated in SIM mode for ions m/z 212, 240, and 360. The limit of quantitation was 0.10 {micro}g/mL by LC/MS/MS versus 0.15 {micro}g/mL for GC/MS. Fortifications of the beverages at 2.5 {micro}g/mL and 0.25 {micro}g/mL were recovered ranging from 73-128% by liquid-liquid extraction for GC/MS analysis, 13-96% by SPE and 10-101% by liquid-liquid extraction for LC/MS/MS analysis.

Owens, J; Hok, S; Alcaraz, A; Koester, C

2008-11-13

277

Analysis of betamethasone, dexamethasone and related compounds by liquid chromatography/electrospray mass spectrometry.  

PubMed

A reversed-phase high-performance liquid chromatography/electrospray ionisation mass spectrometry (HPLC/ESI-MS) method has been developed to conclusively differentiate the epimers betamethasone and dexamethasone and various esterification products (betamethasone and dexamethasone 21-acetate, betamethasone and dexamethasone 21-phosphate, betamethasone 17-valerate, betamethasone 21-valerate and betamethasone 17,21-dipropionate) in counterfeit drugs. Good separation with baseline resolution of all epimers or isomers was obtained on a Zorbax Eclipse XDB or Luna C8 column, using a step gradient with mobile phases of 0.05 M ammonium acetate and acetonitrile. Betamethasones can also be distinguished by the relative abundance of their m/z 279 ion in the positive electrospray tandem mass spectra. The LC/MS or LC/MS/MS method developed was successfully applied to the analysis of drug product samples, i.e. creams and tablets. PMID:15052579

Arthur, Kathryn E; Wolff, Jean-Claude; Carrier, Dan J

2004-01-01

278

Analysis of Monosodium l-Glutamate in Food Products by High-Performance Thin Layer Chromatography  

PubMed Central

A simple, fast, specific, and precise high-performance thin layer chromatography method has been developed for the estimation of monosodium l-glutamate (MSG) in food products. Aluminum plates precoated with silica gel 60 GF254were used as stationary phase and a mixture of methanol–chloroform–formic acid in the ratio 5:5:1 (v/v) as mobile phase. Quantification was carried out by postchromatographic derivatization using 1% ninhydrin solution, and the developed spots were scanned by using a densitometer in absorbance mode at 485 nM. The Rfvalue of MSG was 0.64. The results of the analysis have been validated statistically and by the recovery studies. Linearity was observed in the concentration range of 400–1000 nG. PMID:21042489

Krishna, Veni N; Karthika, D; Surya, Devi M; Rubini, MF; Vishalini, M; Pradeepa, YJ

2010-01-01

279

Mycolic Acid Analysis by High-Performance Liquid Chromatography for Identification of Mycobacterium Species  

PubMed Central

Mycobacterium tuberculosis is the etiologic agent of tuberculosis and can be accurately detected by laboratories using commercial genetic tests. Nontuberculosis mycobacteria (NTM) causing other mycobacterioses can be difficult to identify. The identification processes are confounded by an increasing diversity of newly characterized NTM species. The ubiquitous nature of NTM, combined with their potential to be opportunistic pathogens in immunocompromised as well as nonimmunodeficient patients, further complicates the problem of their identification. Since clinical case management varies depending on the etiologic agent, laboratories must identify the species in a timely manner. However, only a few identification methods can detect the species diversity within the Mycobacterium genus. Over the last decade, high-performance liquid chromatography analysis of the mycolic acids has become an accepted method for identification of mycobacteria. In this review, we assess its development and usefulness as an identification technique for Mycobacterium species. PMID:11585782

Butler, W. Ray; Guthertz, Linda S.

2001-01-01

280

Headspace analysis of engine oil by gas chromatography/mass spectrometry.  

PubMed

This study establishes the rationale necessary for determining the time to change engine oil. This is based on identifying gaseous components in new and used automobile lubricants. Key compounds, so-called "signature", are separated and identified qualitatively by coupled gas chromatography/mass spectrometry. Volatile antioxidants at zero miles and fuel contaminants at low mileage are observed in the headspace of engine oil. Several oxidative degradation components have been positively identified in the used oil, which include the following: acetaldehyde, acetone, butanal, 2-propanol, acetic acid, 2-hexanol, benzoic acid, benzaldehyde, and 1-pentanol. This study strongly suggests that the status of lubricating oil can be determined by the analysis of the gas phase above the oil. Most importantly, it opens the possibility of performing conditional maintenance of the combustion engine based on information obtained from gas sensors. PMID:11305675

Levermore, D M; Josowicz, M; Rees, W S; Janata, J

2001-03-15

281

Analysis of the surface energy of pharmaceutical powders by inverse gas chromatography.  

PubMed

The behavior of pharmaceutical solids, during either processing or use, can be noticeably affected by the surface energetics of the constituent particles. Several techniques exist to measure the surface energy, for example, sessile drop, and dynamic contact angle measurements. Inverse gas chromatography (IGC) is an alternative technique where the powder surface is characterized by the retention behavior of minute quantities of well-characterized vapors that are injected into a column containing the material of interest. Recently published articles using IGC on pharmaceutical powders have ranged from linking surface energetic data with triboelectric charging to studying the effect of surface moisture on surface energetics. Molecular modelling has also recently been used to explore the links between IGC data and the structural and chemical factors that influence surface properties, thereby achieving predictive knowledge regarding powder behavior during processing. In this minireview, the reported applications of IGC in the analysis of pharmaceutical powders are summarized and the major findings highlighted. PMID:11835214

Grimsey, Ian M; Feeley, Jane C; York, Peter

2002-02-01

282

Circulating ultrasound-assisted extraction, countercurrent chromatography, and liquid chromatography for the simultaneous extraction, isolation, and analysis of the constituents of Uncaria tomentosa.  

PubMed

A hyphenated automated technique for the online extraction, isolation, analysis, and identification of natural organic compounds was established. Circulating ultrasound-assisted extraction (CUAE) was coupled with countercurrent chromatography (CCC), high performance liquid chromatography (HPLC), and a diode array detector (DAD). This approach was applied to the fractionation and purification of alkaloids from Uncaria tomentosa. A biphasic solvent system of chloroform-methanol-water (6:4:5, v:v:v) was used for the CUAE and CCC separation of compounds from 500g of U. tomentosa. Two CUAE/CCC/HPLC/DAD modes were established. Either the upper aqueous phase or the lower organic phase of the solvent system could be used as the extraction solvent. The target compounds were extracted by CUAE, and the extract was pumped into a sample loop before being directly injected into the CCC column, or pre-purified using a flash chromatography column before injection. The target compounds were eluted using either the organic or aqueous phase of the solvent system and the fractions were monitored using a UV detector. The target fractions were collected by a sample loop via a six-port valve, and analyzed by HPLC/DAD for purity and structural identification. This system isolated of 8.2mg, 7.4mg, and 12.9mg of rhynchophylline, corynoxine, and corynoxine B with HPLC purities of 96.15%, 95.34%, and 95.49%, respectively via the first mode; and isolated 26.6mg, 24.6mg, and 45.3mg of rhynchophylline, corynoxine, and corynoxine B with a HPLC purities of 98.22%, 97.18%, and 97.93% via the second mode. PMID:25725954

Zhang, Yuchi; Liu, Chunming; Qi, Yanjuan; Li, Sainan; Pan, Yan; Li, Yuchun

2015-04-01

283

[Analysis of phthalates in plastic food-packaging bags by thin layer chromatography].  

PubMed

The method for simultaneous determination of four phthalates, namely dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP) and di (2-ethylhexyl) phthalate (DEHP) in plastic food-packaging bags by thin layer chromatography (TLC) was developed. The plastic food-packaging bags were extracted with ethanol by ultrasonication, then the mixture was filtrated through membrane (0.45 microm). The mixture of ethyl acetate-anhydrous ether-isooctane (1 : 4 : 15, v/v) was used as developing agent on the TLC silica gel plate for development. The filtered liquid was spotted on the TLC plate dealt by acetone, and detected with scanning wavelength of 275 nm and reference wavelength of 340 nm. The qualitative analysis of the phthalates was performed using the R(f) values of the chromatogram. The quantitative analysis was performed with external standard method. Good linearities were obtained for DMP, DEP, DBP and DEHP. The detection limits were 2.1 ng for DMP, 2.4 ng for DEP, 3.4 ng for DBP and 4.0 ng for DEHP. The relative standard deviations (RSDs) of the four phthalates were 2.8% - 3.5%. The recoveries of the four phthalate standards in real sample were 78.58% - 111.04%. The method presented has the advantages of high precision, high sensitivity, small sample size, and simple pretreatment . The method was used to detect the four phthalates in the food-packaging bags. The contents in real samples were close to the results by gas chromatography. PMID:16827317

Chen, Hui; Wang, Yuan; Zhu, Ruohua

2006-01-01

284

Chemical fingerprint and quantitative analysis of Salvia plebeia R.Br. by high-performance liquid chromatography  

Microsoft Academic Search

To control the quality of Salvia plebeia R.Br., a simple and reliable method of high-performance liquid chromatography coupled with photodiode array detector (HPLC-DAD) was developed both for fingerprint analysis and quantitative determination of seven bioactive compounds, namely caffeic acid, luteolin-7-glucoside, nepetin-7-glucoside, homoplantaginin, luteolin, nepetin and hispidulin. In fingerprint analysis, twelve peaks were selected as characteristic peaks. In quantitative analysis, seven

Xiao-feng Jin; Yan-hua Lu; Dong-zhi Wei; Zheng-tao Wang

2008-01-01

285

Authentication of beeswax (Apis mellifera) by high-temperature gas chromatography and chemometric analysis.  

PubMed

Chemical characterization and authentication of beeswax of Apis mellifera was performed by high temperature capillary gas chromatography coupled to electron impact mass spectrometry or to flame ionisation detection and chemometric analysis. Many major components (>50) of beeswax, odd and even hydrocarbons, oleofin, palmitate, oleate and hydroxypalmitate monoesters were detected, and for the first time palmitate and oleate monoesters esterified with 1-octadecanol and 1-eicosanol are reported to be present in beeswax. Unsupervised pattern recognition procedures, cluster analysis and principal component analysis, were used to find data patterns and successfully differentiate authentic and paraffin adulterated beeswax based on the chemical profile obtained. Independent assessment of beeswax quality and performance of the unsupervised classification methods were performed using classical analytical parameters. The discrimination power of the chemometric unsupervised methods for detection of paraffin adulterated beeswax was superior to the discriminating power of classical analytical parameters. Using linear discriminant analysis, classification rules for authentic and paraffin adulterated beeswax samples were developed. The model was validated by leave-one-out cross validation and showed good recognition and prediction abilities, 100% and 99%, respectively. PMID:23122150

Maia, Miguel; Nunes, Fernando M

2013-01-15

286

Effect of surface condition on the flow in segmented gas-liquid microreactors  

NASA Astrophysics Data System (ADS)

The mixing process within segmented gas-liquid microreactors is of significance importance in design and optimization of devices for high throughput material synthesis. In a typical slug flow regime the liquid slugs are connected through a thin liquid film that plays an important role in hydrodynamics of the microreactor flow. Among the parameters that can influence the thin film layer, and the overall flow, is the surface condition of microchannel walls. We present preliminary results of this influence in the segmented gas-liquid flow of Ethanol/Nitrogen within PDMS microreactors. The results are presented specifically for microreactors with different level of roughness on the channel walls. The range of stable slug flow regime and behavior of liquid film are studied as a function of surface roughness.

Pouya, Shahram; Koochesfahani, Manoochehr

2010-11-01

287

US crude oil, natural gas, and natural gas liquids reserves, 1992 annual report  

SciTech Connect

This report presents estimates of proved reserves of crude oil, natural gas, and natural gas liquids as of December 31, 1992, as well as production volumes for the United States, and selected States and State subdivisions for the year 1992. Estimates are presented for the following four categories of natural gas: total gas (wet after lease separation), its two major components (nonassociated and associated-dissolved gas), and total dry gas (wet gas adjusted for the removal of liquids at natural gas processing plants). In addition, two components of natural gas liquids, lease condensate and natural gas plant liquids, have their reserves and production data presented. Also included is information on indicated additional crude oil reserves and crude oil, natural gas, and lease condensate reserves in nonproducing reservoirs. A discussion of notable oil and gas exploration and development activities during 1992 is provided.

Not Available

1993-10-18

288

Optimized conditions for hydrocarbon group type analysis of base oils by thin-layer chromatography–flame ionisation detection  

Microsoft Academic Search

The results of research on the optimization of the thin-layer chromatography–flame ionisation detection for the determination of group composition of natural base oils, including separation of the aromatics into subgroups, are presented. Neutral base oils obtained in several steps of refining from vacuum distillation petroleum fractions are the most difficult to analyze by hydrocarbon group type analysis (HGTA) because of

Marian Kami?ski; Joanna Gudebska; Tadeusz Górecki; Rafa? Kartanowicz

2003-01-01

289

ANALYSIS OF OCTYL- AND NONYLPHENOL AND THEIR ETHOXYLATES IN WATER AND SEDIMENTS BY LIQUID CHROMATOGRAPHY-TANDEM MASS SPECTROMETRY  

Technology Transfer Automated Retrieval System (TEKTRAN)

A quantitative method for the analysis of octyl- and nonylphenol, and their ethoxylates (1 to 5) in water and sediment is presented. Extraction procedures are based on solid-phase extraction techniques. Identification and quantitation of the analytes is done by liquid chromatography coupled to tan...

290

Chemical Speciation Analysis of Sports Drinks by Acid-Base Titrimetry and Ion Chromatography: A Challenging Beverage Formulation Project  

ERIC Educational Resources Information Center

Students have standardized a sodium hydroxide solution and analyzed commercially available sports drinks by titrimetric analysis of the triprotic citric acid, dihydrogen phosphate, and dihydrogen citrate and by ion chromatography for chloride, total phosphate and citrate. These experiments are interesting examples of analyzing real-world food and…

Drossman, Howard

2007-01-01

291

DETERMINATION OF VOLATILE ORGANIC COMPOUNDS IN SOILS USING EQUILIBRIUM HEADSPACE ANALYSIS AND CAPILLARY COLUMN GAS CHROMATOGRAPHY/MASS SPECTROMETRY  

EPA Science Inventory

Existing methods for determination of volatile organic compounds (VOCs) in soil matrices using the purge and trap technique with gas chromatography/mass spectrometry (GC/MS) have several problems, which include preserving sample integrity from collection to analysis and efficient...

292

ISOTOPE DILUTION ANALYSIS OF BROMATE IN DRINKING WATER MATRIXES BY ION CHROMATOGRAPHY WITH INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRIC DETECTION  

EPA Science Inventory

Bromate is a disinfection byproduct in drinking water which is formed during the ozonation of source water containing bromide. This paper described the analysis of bromate via ion chromatography-inductively coupled plasma mass spectrometry. The separation of bromate from interfer...

293

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

EPA Science Inventory

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

294

A Laboratory Experiment in Pharmaceutical Analysis: Determination of Drugs of Abuse in Human Urine by Thin-Layer Chromatography.  

ERIC Educational Resources Information Center

An experiment is described that was developed for a course in Inorganic and Analytical Pharmaceutical Chemistry at Rutgers University to provide pharmacy students with practical experience in the thin-layer chromatography used for the analysis of urine to monitor patient compliance with drug abuse treatment programs. (JMD)

Bailey, Leonard C.

1979-01-01

295

Droplets in annular-dispersed gas-liquid pipe-flows  

Microsoft Academic Search

Annular-dispersed gas-liquid pipe-flows are commonly encountered in many industrial applications, and have already been studied for many decades. However, due to the great\\u000acomplexity of this type of flow, there are still many phenomena that are poorly understood. The aim of this thesis is to shed more light on some of these processes\\u000ainvolving the dispersed-phase of an annular-dispersed flow.

J. M. C. Van't Westende

2008-01-01

296

Application of a borescope to studies of gas–liquid flow in downward inclined pipes  

Microsoft Academic Search

The aim of the present study is to investigate stratified downward gas–liquid pipe flow with a non-intrusive measurement technique that is based on a borescope connected to a digital video camera. The borescope-based technique enables to determine the instantaneous cross-sectional distribution of both phases within the pipe. Water and air were used as working fluids. Quantitative data was extracted from

L. Shemer; D. Barnea

2006-01-01

297

Dynamic simulation of dispersed gas-liquid two-phase flow using a discrete bubble model  

Microsoft Academic Search

In this paper a detailed hydrodynamic model for gas-liquid two-phase flow will be presented. The model is based on a mixed Eulerian-Lagrangian approach and describes the time-dependent two-dimensional motion of small, spherical gas bubbles in a bubble column operating in the homogeneous regime. The motion of these bubbles is calculated from a force balance for each individual bubble, accounting for

E. Delnoij; F. A. Lammers; J. A. M. Kuipers; W. P. M. van Swaaij

1997-01-01

298

Heat transfer in gas-liquid and liquid-liquid two phase plug flow systems  

Microsoft Academic Search

Liquid-gas and liquid-liquid two phase flows are examined. It has been recently documented that gas-liquid segmented flows offer a thermal enhancement advantage over single phase flows, since the plug flow (Taylor flow) regime produces internal circulations which enhance radial transport. Additional strategies in liquid-gas and liquid-liquid cooling are being pursued with liquid cooled heat sinks. Proper heat transfer and pressure

N. Janes; Y. S. Muzychka; B. Guy; E. J. Walsh; P. Walsh

2010-01-01

299

Ultrasound tomography system used for monitoring bubbly gas\\/liquid two-phase flow  

Microsoft Academic Search

This paper is about a transmission-mode (TM) ultrasound computerized tomography (UCT) system, which is used to monitor a bubbly gas\\/liquid two-phase flow, a kind of strongly inhomogeneous medium. Because of the high contrast in acoustic impedance distribution of the flow, TM UCT system can only obtain incomplete tomographic projections which depend on the distribution of bubbles in liquid. In order

Li-Jun Xu; Ling-An Xu

1997-01-01

300

Effect of Inlet Geometry on Adiabatic Gas-Liquid Two-Phase Flow in a Microchannel  

Microsoft Academic Search

An optical measurement system and video camera were used to investigate gas-liquid two-phase flow characteristics in a circular microchannel of 100 ?m diameter. By cross-correlating the signals from two pairs of optical fibers and infrared photodiodes, void fraction and the lengths and velocities of gas slugs and liquid slugs were measured. The data were obtained using a T-junction with the

Hideo Ide; Ryuji Kimura; Masahiro Kawaji

2008-01-01

301

Gas–liquid two-phase flow distributions in parallel channels for fuel cells  

Microsoft Academic Search

In the present study, gas–liquid two-phase flow in a parallel square minichannel system oriented horizontally and at an incline is studied under operating conditions relevant to fuel cell operations. Flow mal-distribution in parallel channels occurs at low gas and liquid flow rates. In general, high superficial gas velocities are required to ensure even flow distribution, and the minimum gas flow

Lifeng Zhang; Wei Du; Hsiaotao T. Bi; David P. Wilkinson; Jürgen Stumper; Haijiang Wang

2009-01-01

302

Miniature conductivity wire-mesh sensor for gas-liquid two-phase flow measurement  

Microsoft Academic Search

A miniature conductivity wire-mesh sensor for gas-liquid two-phase flow measurement in small channels is presented. The sensor design is similar to the conventional wire-mesh sensor for larger flow cross sections with wire electrodes stretched across the flow channel in two adjacent planes and with perpendicular wire orientation between planes. Conductivity measurement is performed by special electronics which consecutively applies bipolar

U. Hampel; J. Otahal; S. Boden; M. Beyer; E. Schleicher; W. Zimmermann; M. Jicha

2009-01-01

303

Frictional stress at the wall in an ascending gas-liquid flow  

Microsoft Academic Search

The results of experiments dealing with upward gas-liquid flow are described. A solution of 0.5 N sodium hydroxide and 0.01 N potassium ferri- and ferro-cyanide in distilled water was used, while nitrogen was used as gas phase. The test section was 86.4 mm in diameter and 6.5 m long. The frictional stress at the wall, local gas content and liquid

A. P. Burdukov; O. N. Kashinskii

1981-01-01

304

Gas–liquid mass transfer in a slurry bubble column operated at gas hydrate forming conditions  

Microsoft Academic Search

Gas–liquid interphase mass transfer was investigated in a slurry bubble column under CO2 hydrate forming operating conditions. Modeling gas hydrate formation requires knowledge of mass transfer and the hydrodynamics of the system. The pressure was varied from 0.1 to 4MPa and the temperature from ambient to 277K while the superficial gas velocity reached 0.20m\\/s. Wettable ion-exchange resin particles were used

Shahrzad Hashemi; Arturo Macchi; Phillip Servio

2009-01-01

305

Preparation of nanoparticles with a semi-batch gas–liquid membrane contactor  

Microsoft Academic Search

Nanosized calcium carbonate particles were prepared with a semi-batch gas–liquid membrane contactor. A mathematical model of the semi-batch operated contactor was given, and the effects of Ca(OH)2 concentration, CO2 partial pressure and additives on the absorption rate were estimated theoretically. The predicted data were consistent with the experimental results. The Ca(OH)2 concentration and CO2 pressure have no apparent effects on

Zhiqian Jia; Qing Chang; Aynur Mamat

2011-01-01

306

Inactivation of algae in ballast water with multi-needle gas-liquid hybrid discharge reactor  

Microsoft Academic Search

Pulsed high-voltage discharge is a new advanced oxidation water treatment technology. Plasma technology has recently become significant because it offers the advantages of lower costs, higher treatment and energy efficiencies, and the smaller space volume it occupies. The present work investigates the use of a multi-needle plate reactor with gas-liquid hybrid discharge system to sterilize ballast water. The optimal sterilization

Nyein Nyein Aye; Sun Bing; Xiaomei Zhu; Zhiying Gao; Masayuki Sato

2010-01-01

307

Comparison and analysis of organochlorine pesticides and hexabromobiphenyls in environmental samples by gas chromatography-electron capture detector and gas chromatography-mass spectrometry.  

PubMed

Two analytical methods, gas chromatography-electron capture detector (GC-ECD) and gas chromatography-negative chemical ionization-mass spectrometry (GC-NCI-MS), were evaluated and compared for the measurement of persistent organic pollutants, specifically for 26 organochlorine pesticides and two hexabromobiphenyls, in atmospheric particulate matter and soil samples. The hypothesis tested was that the coelution of non-target compounds may lead to false positives when analyzed by GC-ECD, and that the overestimation associated with these false positives can be eliminated using GC-NCI-MS. The study showed that both methods had satisfactory linearity and reproducibility for the target compounds. Although the sensitivities of GC-ECD for most of the compounds investigated were higher than those observed with the GC-NCI-MS method, the matrices interference was obvious with GC-ECD. There was indeed an apparently high false-positive rate or overestimate when GC-ECD was used for environmental samples, implying that the GC-ECD method has been used with care and that GC-NCI-MS is generally superior for the analysis of trace amounts of these compounds in environmental samples. Based on these results, the sample extraction and cleanup procedures of the GC-NCI-MS method were optimized for achieving acceptable recoveries and less matrices interference. PMID:24872522

Liu, Yu; Fu, Xiaofang; Tao, Shu; Liu, Liang; Li, Wei; Meng, Bingjun

2015-02-01

308

Annual report of the origin of natural gas liquids production form EIA-64A  

SciTech Connect

The collection of basic, verifiable information on the Nation`s reserves and production of natural gas liquids (NGL) is mandated by the Federal Energy Administration Act of 1974 (FEAA) (Public Law 93-275) and the Department of Energy Organization Act of 1977 (Public Law 95-91). Gas shrinkage volumes reported on Form EIA-64A by natural gas processing plant operators are used with natural gas data collected on a {open_quotes}wet after lease separation{close_quotes} basis on Form EIA-23, Annual Survey of Domestic Oil and Gas Reserves, to estimate {open_quotes}dry{close_quotes} natural gas reserves and production volumes regionally and nationally. The shrinkage data are also used, along with the plant liquids production data reported on Form EIA-64A, and lease condensate data reported on Form EIA-23, to estimate regional and national gas liquids reserves and production volumes. This information is the only comprehensive source of credible natural gas liquids data, and is required by DOE to assist in the formulation of national energy policies.

NONE

1995-12-31

309

Calculations of Gas-liquid Equilibrium in Wellbore with High Carbon dioxide Flow  

NASA Astrophysics Data System (ADS)

Carbon dioxide injection not only enhances the oil recovery dramatically, but also it will reduce the greenhouse effect, therefore, Carbon dioxide injection technique is applied extensively. During the process of carbon dioxide displacement, when carbon dioxide breaks though into oil production wells, carbon dioxide content will impacts the phase state and physical properties of the mixed liquor in the wellbore, as a result, it will affect the calculation of temperature and pressure in oil production wells. Applying the conventional black-oil model to calculate the phase state of the miscible fluids is unacceptable. To tackle the problem, this paper uses the gas-liquid flash theory and component model to program software, so that the phase state (gas, liquid or gas-liquid) and physical properties of the mixed liquor (including hydrogen sulfide, carbon dioxide and hydrocarbon) under initial conditions is calculated, moreover, the impact of carbon dioxide content on the physical properties(mainly including density, viscosity, specific heat at const pressure, surface tension, etc) of mixed liquor in oil production wells is analyzed in this paper. The comparison of the results shows that this model can meet the engineering needs with high accuracy.

Zhang, Jiaming; Wu, Xiaodong; Wang, Bo; Liu, Kai; Gao, Yue

2014-05-01

310

Gas-liquid phase coexistence and crossover behavior of binary ionic fluids with screened Coulomb interactions.  

PubMed

We study the effects of an interaction range on the gas-liquid phase diagram and the crossover behavior of a simple model of ionic fluids: an equimolar binary mixture of equisized hard spheres interacting through screened Coulomb potentials which are repulsive between particles of the same species and attractive between particles of different species. Using the collective variables theory, we find explicit expressions for the relevant coefficients of the effective ?{4} Ginzburg-Landau Hamiltonian in a one-loop approximation. Within the framework of this approximation, we calculate the critical parameters and gas-liquid phase diagrams for varying inverse screening length z. Both the critical temperature scaled by the Yukawa potential contact value and the critical density rapidly decrease with an increase of the interaction range (a decrease of z) and then for z<0.05 they slowly approach the values found for a restricted primitive model (RPM). We find that gas-liquid coexistence region reduces with an increase of z and completely vanishes at z?2.78. Our results clearly show that an increase in the interaction range leads to a decrease of the crossover temperature. For z?0.01, the crossover temperature is the same as for the RPM. PMID:25019760

Patsahan, O

2014-06-01

311

Gas-liquid phase coexistence and crossover behavior of binary ionic fluids with screened Coulomb interactions  

NASA Astrophysics Data System (ADS)

We study the effects of an interaction range on the gas-liquid phase diagram and the crossover behavior of a simple model of ionic fluids: an equimolar binary mixture of equisized hard spheres interacting through screened Coulomb potentials which are repulsive between particles of the same species and attractive between particles of different species. Using the collective variables theory, we find explicit expressions for the relevant coefficients of the effective ?4 Ginzburg-Landau Hamiltonian in a one-loop approximation. Within the framework of this approximation, we calculate the critical parameters and gas-liquid phase diagrams for varying inverse screening length z. Both the critical temperature scaled by the Yukawa potential contact value and the critical density rapidly decrease with an increase of the interaction range (a decrease of z) and then for z <0.05 they slowly approach the values found for a restricted primitive model (RPM). We find that gas-liquid coexistence region reduces with an increase of z and completely vanishes at z ?2.78. Our results clearly show that an increase in the interaction range leads to a decrease of the crossover temperature. For z ?0.01, the crossover temperature is the same as for the RPM.

Patsahan, O.

2014-06-01

312

Microporous hydrophobic hollow fiber modules for gas-liquid phase separation in microgravity  

NASA Astrophysics Data System (ADS)

Gas-liquid interphase mass transfer operations, such as gas-liquid phase separation, gas absorption into liquid or dissolved gas separation from liquid, gas humidification and drying via liquid contact, and evaporative cooling are readily accomplished on the Earth with settling/spray chambers, packed towers, or bubble columns. This paper reports on gas-water mass transfer tests performed utilizing microporous hydrophobic Hollow Fiber Modules (HFMs) of the type currently employed as blood oxygenators in heart-lung machines. In these HFMs, gases are transferrred to and from water or other hydrophilic liquids through the microporous fiber walls; liquid water does not enter the pores of the highly hydrophobic wall material. The experiments included air-water phase separation, absorption of oxygen and carbon dioxide into water and separation of these dissolved gases from water, air humidification and drying by contact with temperature-controlled water, and controlled evaporation of water into a vacuum. In each of these experiments, a small, light HFM sucessfully performed the mass tranfer function, with no leakage of liquid water through the porous walls of the hollow fibers, even with high pressure across the fiber wall for extended periods of time. These results demonstrate that gas-liquid mass transfer unit operations on hydrophilic liquids, implemented with microporous hydrophobic HFM technology, are ready for use in microgravity fluid processing systems.

Noyes, Gary

313

Gas Chromatography  

NASA Astrophysics Data System (ADS)

Gas chromatography (GC) has many applications in the analysis of food products. GC has been used for the determination of fatty acids, triglycerides, cholesterol, gases, water, alcohols, pesticides, flavor compounds, and many more. While GC has been used for other food components such as sugars, oligosaccharides, amino acids, peptides, and vitamins, these substances are more suited to analysis by high performance liquid chromatography. GC is ideally suited to the analysis of volatile substances that are thermally stable. Substances such as pesticides and flavor compounds that meet these criteria can be isolated from a food and directly injected into the GC. For compounds that are thermally unstable, too low in volatility, or yield poor chromatographic separation due to polarity, a derivatization step must be done before GC analysis. The two parts of the experiment described here include the analysis of alcohols that requires no derivatization step, and the analysis of fatty acids which requires derivatization. The experiments specify the use of capillary columns, but the first experiment includes conditions for a packed column.

Qian, Michael C.

314

The use of a milli-whistle as a detector in gas analysis by gas chromatography.  

PubMed

This mini-review introduces a general understanding of the use of a milli-whistle as a gas chromatography (GC) detector in gas analysis, including our research on the methodology and theory associated with a number of different related applications. The milli-whistle is connected to the outlet of a GC capillary, and when the eluted gases and the GC carrier gas pass through it, a sound with a fundamental frequency is produced. The sound wave can be picked up by a microphone or an accelerometer, and after a fast Fourier transform, the online data obtained for frequency-change vs. retention time constitute a new method for detecting gases. The first part of this review discusses the fundamentals of the milli-whistle. Some modifications are also discussed, including various types of whistles and an attempt to maximize the sensitivity and stability of the method. The second part then focuses on several practical applications, including an analysis of hydrogen released from ammonia borane, inorganic gases produced from fireworks, the CO2/O2 ratio from expired human breath and a purity test for alcohols. These studies show that the GC-whistle method has great potential for use as a fast sampling ionization method, and for the direct analysis of biological and chemical samples at under ambient conditions. PMID:24420261

Lin, Cheng-Huang; He, Yi-San; Lin, Chien-Hung; Fan, Gang-Ting; Chen, Hsin-Kai

2014-01-01

315

Disaccharide analysis of glycosaminoglycan mixtures by ultra-high-performance liquid chromatography-mass spectrometry.  

PubMed

Glycosaminoglycans are a family of polysaccharides widely distributed in all eukaryotic cells. These polyanionic, linear chain polysaccharides are composed of repeating disaccharide units that are often differentially substituted with sulfo groups. The diversity of glycosaminoglycan structures in cells, tissues and among different organisms reflect their functional an evolutionary importance. Glycosaminoglycan composition and structure also changes in development, aging and in disease progression, making their accurate and reliable analysis a critical, albeit, challenging endeavor. Quantitative disaccharide compositional analysis is one of the primary ways to characterize glycosaminoglycan composition and structure and has a direct relationship with glycosaminoglycan biological functions. In this study, glycosaminoglycan disaccharides, prepared from heparan sulfate/heparin, chondroitin sulfate/dermatan sulfate and neutral hyaluronic acid using multiple polysaccharide lyases, were fluorescently labeled with 2-aminoacridone, fractionated into 17 well-resolved components by reverse-phase ultra-performance liquid chromatography, and analyzed by electrospray ionization mass spectrometry. This analysis was successfully applied to cell, tissue, and biological fluid samples for the picomole level detection of glycosaminoglycan composition and structure. PMID:22236563

Yang, Bo; Chang, Yuqing; Weyers, Amanda M; Sterner, Eric; Linhardt, Robert J

2012-02-17

316

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

317

Identification of Dactylopius cochineal species with high-performance liquid chromatography and multivariate data analysis.  

PubMed

Identification of American cochineal species (Dactylopius genus) can provide important information for the study of historical works of art, entomology, cosmetics, pharmaceuticals and foods. In this study, validated species of Dactylopius, including the domesticated cochineal D. coccus, were analysed by high-performance liquid chromatography with a diode array detector (HPLC-DAD) and submitted to multivariate data analysis, in order to discriminate the species and hence construct a reference library for a wide range of applications. Principal components analysis (PCA) and partial least squares discriminant analysis (PLSDA) models successfully provided accurate species classifications. This library was then applied to the identification of 72 historical insect specimens of unidentified species, mostly dating from the 19th century, and belonging to the Economic Botany Collection, Royal Botanic Gardens, Kew, England. With this approach it was possible to identify anomalies in how insects were labelled historically, as several of them were revealed not to be cochineal. Nevertheless, more than 85% of the collection was determined to be species of Dactylopius and the majority of the specimens were identified as D. coccus. These results have shown that HPLC-DAD, in combination with suitable chemometric methods, is a powerful approach for discriminating related cochineal species. PMID:23961534

Serrano, Ana; Sousa, Micaela; Hallett, Jessica; Simmonds, Monique S J; Nesbitt, Mark; Lopes, João A

2013-10-21

318

Analysis of mutagens from cooked foods by directly combined liquid chromatography-mass spectrometry.  

PubMed Central

Directly combined high performance liquid chromatography-mass spectrometry (LC/MS) has been studied as a method of analysis of heterocyclic aromatic mutagens in cooked foods, in the parts per billion concentration range. Identification and semiquantitative estimation of mutagens is based on accurate measurement of chromatographic retention (k') and molecular weight-selective detection of mutagens, which are protonated during passage of the chromatographic eluant into a thermospray interface of a quadrupole mass spectrometer. Standard chromatographic retention (k') values in two reversed-phase systems and data from thermospray mass spectra from nine mutagens are reported. An isolation scheme employing CH3OH extraction, acid-base partition, cellulose-trisulfo-Cu-phthalocyanine adsorption, and normal-phase HPLC was used prior to LC/MS analysis. Initial applications have been demonstrated in the analysis of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) in broiled salmon flesh. Levels measured were estimated to be in the range 0.2 to 0.4 microgram/kg IQ and 0.4 to 0.9 microgram/kg MeIQ. The method is judged to be generally applicable with minimal sample prefractionation to detection of mutagens at the parts per billion level in cooked foods. PMID:3757957

Edmonds, C G; Sethi, S K; Yamaizumi, Z; Kasai, H; Nishimura, S; McCloskey, J A

1986-01-01

319

Native fluorescent detection with sequential injection chromatography for doping control analysis  

PubMed Central

Background Sequential injection chromatography (SIC) is a young, ten years old, separation technique. It was proposed with the benefits of reagent-saving, rapid analysis, system miniaturization and simplicity. SIC with UV detection has proven to be efficient mostly for pharmaceutical analysis. In the current study, a stand-alone multi-wavelength fluorescence (FL) detector was coupled to an SIC system. The hyphenation was exploited for developing an SIC-FL method for the separation and quantification of amiloride (AML) and furosemide (FSM) in human urine and tablet formulation. Results AML and FSM were detected using excitation maxima at 380 and 270 nm, respectively, and emission maxima at 413 and 470 nm, respectively. The separation was accomplished in less than 2.0 min into a C18 monolithic column (50?×?4.6 nm) with a mobile phase containing 25 mmol/L phosphate buffer (pH 4.0): acetonitrile: (35:65, v/v). The detection limits were found to be 12 and 470 ng/mL for AML and FSM, respectively. Conclusions The proposed SIC-FL method features satisfactory sensitivity for AML and FSM in urine samples for the minimum required performance limits recommended by the World Anti-Doping Agency, besides a downscaled consumption of reagents and high rapidity for industrial-scale analysis of pharmaceutical preparations. PMID:23985079

2013-01-01

320

Rapid separation, identification and analysis of Astragalus membranaceus Fisch using liquid chromatography-tandem mass spectrometry.  

PubMed

A rapid, sensitive and selective liquid chromatography-tandem mass spectrometry (HPLC-MS-MS) method has been developed for the rapid separation and structural identification of constituents in Astragali Radix (AR) The analysis was conducted on an ACQUITY HPLC chromatographic instrument and a mass spectrometer using positive electrospray ionization. Using a fast HPLC system with an ACQUITY HPLC BEH C18 column, the total analysis time for this complex herb was less than 30 min. The method used a column with 1.7 µm particle packing, which allowed a higher speed of analysis, peak capacity, greater resolution and increased sensitivity. With various fragmentor voltage levels in MS, accurate mass measurements (less than 5 ppm error) for molecular ions and characteristic fragment ions represented reliable identification criteria for these compounds. The constituents of AR were identified or tentatively characterized based on their retention times, mass fragmentation behavior, MS-MS fragment ions, literature reports and the establishment of an in-house molecular formula database. With this method, a total of 22 compounds of AR were tentatively identified based on MS data and comparison with available databases. In conclusion, fast HPLC with MS is a highly useful and efficient technique to separate and identify constituents in complex matrices of herbal medicines. PMID:23519564

Du, Hong-wei; Zhao, Xin-lei; Zhang, Ai-hua; Yao, Lin; Zhang, Yan-yan

2014-03-01

321

Analysis of sugars in bee pollen and propolis by ligand exchange chromatography in combination with pulsed amperometric detection and mass spectrometry  

Microsoft Academic Search

The analysis of sugars in the natural products propolis and bee pollen was carried by high-performance thin layer chromatography (HPTLC), high-performance ligand exchange chromatography with pulsed amperometric detection (HPLEC-PAD) and HPLEC coupled to liquid chromatography–electrospray ionisation mass spectrometry (LC–ESI-MS) in the positive ion mode. Eleven samples of propolis were analysed, most of which contained no sugars or only traces of

Wei Liang Qian; Zeeshan Khan; David G. Watson; James Fearnley

2008-01-01

322

Visualization of gas–liquid mass transfer and wake structure of rising bubbles using pH-sensitive PLIF  

E-print Network

A planar laser-induced fluorescence (PLIF) technique for visualizing gas–liquid mass transfer and wake structure of rising gas bubbles is described. The method uses an aqueous solution of the pH-sensitive dye Naphthofluorescein ...

Stohr, M.

323

Characterization of human expired breath by solid phase microextraction and analysis using gas chromatography-mass spectrometry and differential mobility spectrometry  

E-print Network

Breath analysis has potential to become a new medical diagnostic modality. In this thesis, a method for the analysis of human expired breath was developed using gas chromatography-mass spectroscopy. It was subsequently ...

Merrick, William (William F. W.)

2005-01-01

324

Effect of Channel Length on the Gas-Liquid Two-Phase Flow Phenomena in a Microchannel  

Microsoft Academic Search

An optical measurement system was used to investigate the effect of microchannel length and inlet geometery on adiabatic gas-liquid two-phase flow. Experiments were conducted with 146 mm and 1,571 mm long, circular microchannels of 100 micron diameter. Void fraction and gas and liquid plug\\/slug lengths and their velocities were measured for two inlet configurations for gas-liquid mixing, i.e., (a) reducer

Hideo Ide; Ryuji Kimura; Hiroshi Hashiguchi; Masahiro Kawaji

2012-01-01

325

Characteristics of Two-Phase Flows in a Rectangular Microchannel with a T-Junction Type Gas-Liquid Mixer  

Microsoft Academic Search

In this study, gas–liquid two-phase flows in a horizontal rectangular microchannel have been investigated. The rectangular microchannel has a hydraulic diameter of 0.235 mm, and a width and depth of 0.24 mm and 0.23 mm, respectively. A T-junction-type gas–liquid mixer was used to introduce gas and liquid in the channel. In order to know the effects of liquid properties, distilled

Akimaro Kawahara; Michio Sadatomi; Keitaro Nei; Hideki Matsuo

2011-01-01

326

Gas chromatography mass spectrometry computer analysis of volatile halogenated hydrocarbons in man and his environment--A multimedia environmental study.  

PubMed

As part of a study to make a comparative analysis of selected halogenated compounds in man and the environmental media, a quantitative gas chromatography mass spectrometric analysis of the levels of the halogenated compounds found in the breath, blood and urine of an exposed population (Old Love Canal area, Niagara, New York) and their immediate environment (air and water) was undertaken. In addition, levels of halogenated hydrocarbons in air samples taken in the general Buffalo, Niagara Falls area were determined. PMID:7448328

Barkley, J; Bunch, J; Bursey, J T; Castillo, N; Cooper, S D; Davis, J M; Erickson, M D; Harris, B S; Kirkpatrick, M; Michael, L C; Parks, S P; Pellizzari, E D; Ray, M; Smith, D; Tomer, K B; Wagner, R; Zweidinger, R A

1980-04-01

327

Recent advances in ultra-high performance liquid chromatography for the analysis of traditional chinese medicine  

Technology Transfer Automated Retrieval System (TEKTRAN)

Traditional Chinese medicines (TCMs) have been widely used for the prevention and treatment of various diseases for thousands of years in China. Ultra Performance Liquid Chromatography (UHPLC) is a relatively new technique offering new possibilities in liquid chromatography. This paper reviews recen...

328

Journal of Chromatography A, 1169 (2007) 7076 Purification of dinosterol for hydrogen isotopic analysis using  

E-print Network

Journal of Chromatography A, 1169 (2007) 70­76 Purification of dinosterol for hydrogen isotopic extracts derived from sediments, for the purpose of hydrogen isotopic measurement by gas chromatography­isotope the entire peak when subsequent hydrogen isotope analyses are to be performed. This is the first report

Gilli, Adrian

329

On-line analysis of complex hydrocarbon mixtures using comprehensive two-dimensional gas chromatography.  

PubMed

This paper discusses the first setup for on-line qualitative and quantitative comprehensive two-dimensional gas chromatography (GC × GC) of complex hydrocarbon mixtures. A built-in 4-port 2-way valve allows switching between flame ionization detection (FID) and time-of-flight mass spectrometry (TOF-MS) between runs, without the need to cool down and vent the MS. Proper selection of GC carrier gas flow rates enables maximal agreement between the obtained chromatograms in both configurations. For on-line analysis of reactor effluents, a dedicated sampling system allows automatic sampling of the hot reactor effluent gases and immediate injection of the sample on the GC × GC. To determine a complete effluent composition in a single run of the GC × GC, a subzero oven starting temperature was employed. Modulation is started when the oven temperature reaches 40°C, thus dividing the chromatogram in a conventional 1D and a comprehensive 2D part. This work illustrates the mature and robust character of GC × GC, extending its capabilities from mere laboratory use to on-line routine analysis for industrial processes in the (petro-)chemical industry. PMID:20444456

Van Geem, Kevin M; Pyl, Steven P; Reyniers, Marie-Françoise; Vercammen, Joeri; Beens, Jan; Marin, Guy B

2010-10-22

330

New ways in qualitative and quantitative protein analysis: nano chromatography coupled to element mass spectrometry.  

PubMed

The potential of inductively coupled plasma-mass spectrometry (ICP-MS), which allows element-specific detection of heteroelements (e.g. Se and S) incorporated in protein structures, is highlighted for sensitive qualitative and quantitative protein analysis. ICP-MS coupled to separation techniques such as size exclusion chromatography and gel electrophoresis (via laser ablation) can be employed at different steps in the proteomic workflow. Special emphasis is made on the couplings of capillary and nanoHPLC to ICP-MS that required the development of dedicated interfaces. Element-specific peptide mapping by nanoHPLC-ICP-MS has turned out to be a key technique in combination with peptide sequencing via nanoHPLC-electrospray MS. This could impressively be demonstrated for the identification of selenium-containing proteins in selenium-rich yeast. Furthermore the potential of sulfur isotope dilution analysis in nanoHPLC-ICP-MS is presented as generic tool for highly accurate, absolute protein quantification. PMID:18039489

Schaumlöffel, Dirk

2007-01-01

331

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

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

332

Analysis of plant nucleotide sugars by hydrophilic interaction liquid chromatography and tandem mass spectrometry.  

PubMed

Understanding the intricate metabolic processes involved in plant cell wall biosynthesis is limited by difficulties in performing sensitive quantification of many involved compounds. Hydrophilic interaction liquid chromatography is a useful technique for the analysis of hydrophilic metabolites from complex biological extracts and forms the basis of this method to quantify plant cell wall precursors. A zwitterionic silica-based stationary phase has been used to separate hydrophilic nucleotide sugars involved in cell wall biosynthesis from milligram amounts of leaf tissue. A tandem mass spectrometry operating in selected reaction monitoring mode was used to quantify nucleotide sugars. This method was highly repeatable and quantified 12 nucleotide sugars at low femtomole quantities, with linear responses up to four orders of magnitude to several 100pmol. The method was also successfully applied to the analysis of purified leaf extracts from two model plant species with variations in their cell wall sugar compositions and indicated significant differences in the levels of 6 out of 12 nucleotide sugars. The plant nucleotide sugar extraction procedure was demonstrated to have good recovery rates with minimal matrix effects. The approach results in a significant improvement in sensitivity when applied to plant samples over currently employed techniques. PMID:24299991

Ito, Jun; Herter, Thomas; Baidoo, Edward E K; Lao, Jeemeng; Vega-Sánchez, Miguel E; Michelle Smith-Moritz, A; Adams, Paul D; Keasling, Jay D; Usadel, Björn; Petzold, Christopher J; Heazlewood, Joshua L

2014-03-01

333

Detection of non-milk fat in milk fat by gas chromatography and linear discriminant analysis.  

PubMed

Gas chromatography was utilized to determine triacylglycerol profiles in milk and non-milk fat. The values of triacylglycerol were subjected to linear discriminant analysis to detect and quantify non-milk fat in milk fat. Two groups of milk fat were analyzed: A) raw milk fat from the central region of Mexico (n = 216) and B) ultrapasteurized milk fat from 3 industries (n = 36), as well as pork lard (n = 2), bovine tallow (n = 2), fish oil (n = 2), peanut (n = 2), corn (n = 2), olive (n = 2), and soy (n = 2). The samples of raw milk fat were adulterated with non-milk fats in proportions of 0, 5, 10, 15, and 20% to form 5 groups. The first function obtained from the linear discriminant analysis allowed the correct classification of 94.4% of the samples with levels <10% of adulteration. The triacylglycerol values of the ultrapasteurized milk fats were evaluated with the discriminant function, demonstrating that one industry added non-milk fat to its product in 80% of the samples analyzed. PMID:19389942

Gutiérrez, R; Vega, S; Díaz, G; Sánchez, J; Coronado, M; Ramírez, A; Pérez, J; González, M; Schettino, B

2009-05-01

334

Global Analysis of the Membrane Subproteome of Pseudomonas aeruginosa using Liquid Chromatography-Tandem Mass Spectrometry  

SciTech Connect

Pseudomonas aeruginosa is one of the most significant opportunistic bacterial pathogens in humans causing infections and premature death in patients with cystic fibrosis, AIDS, severe burns, organ transplants or cancer. Liquid chromatography coupled online with tandem mass spectrometry (LC-MS/MS) was used for the large-scale proteomic analysis of the P. aeruginosa membrane subproteome. Concomitantly, an affinity labeling technique, using iodoacetyl-PEO biotin to tag cysteinyl-containing proteins, permitted the enrichment and detection of lower abundance membrane proteins. The application of these approaches resulted in the identification of 786 proteins. A total of 333 proteins (42%) had a minimum of one transmembrane domain (TMD; ranging from 1 to 14) and 195 proteins were classified as hydrophobic based on their positive GRAVY values (ranging from 0.01 to 1.32). Key integral inner and outer membrane proteins involved in adaptation and antibiotic resistance were conclusively identified, including the detection of 53% of all predicted opr-type porins (outer integral membrane proteins) and all the components of the mexA-mexB-oprM transmembrane protein complex. This work represents the most comprehensive qualitative proteomic analysis of the membrane subproteome of P. aeruginosa and for prokaryotes in general to date.

Blonder, Josip; Goshe, Michael B.; Xiao, Wenzhong; Camp, David G.; Wingerd, Mark A.; Davis, Ronald W.; Smith, Richard D.

2004-05-30

335

Targeted multidimensional gas chromatography for the quantitative analysis of suspected allergens in fragrance products.  

PubMed

Two approaches are described and compared for the analysis of suspected allergens (SAs) in fragrance products, which are defined by the Scientific Committee of Cosmetics and Non-Food Products (SCCNFP). The first consists of a comprehensive two-dimensional gas chromatography (GC x GC) experiment using both a "conventional" non-polar/polar column combination and an "inverse" polar/non-polar column set. The second approach uses a targeted multidimensional gas chromatography (MDGC) system employing a Deans type pneumatic switch and a longitudinally modulated cryogenic system (LMCS). It was found that the conventional and inverse column sets complement each other well, providing identification of SAs present. Compounds well retained on the second dimension of one column set were the first to be eluted from the other. In some instances SAs co-eluting with matrix components on the second dimension for a given column set were clearly resolved on the other, although this has the disadvantage of requiring two analytical runs. Targeted MDGC with a non-polar/polar column set, successfully separated all SAs identified within a fragrance product. The instrument is set up in a similar fashion to a GC x GC system though with longer second dimension ((2)D) column, a cryogenic trap at the beginning of the second column, and a pneumatic switch coupling both columns. The data are easier to process than for a GC x GC experiment. The targeted MDGC method has the capacity to deliver far greater efficiency to targeted regions of a primary separation than a GC x GC experiment, whilst still maintaining overall run times similar to those of a conventional one-dimensional (1D) GC experiment. Cryogenic focussing at the beginning of the (2)D column delivers enhanced sensitivity, accurate (2)D retention times and narrow peak widths; these are responsible for an increased resolution obtained from the fast, relatively short (approximately 5 m) (2)D column. The two column set GC x GC analysis provided a quick and effective means to qualitatively determine the presence of six SAs in a commercially available air freshener, however all were not adequately resolved from matrix components. In contrast, quantitation was straightforward using the targeted MDGC method. PMID:16934274

Dunn, Michael S; Vulic, Natalie; Shellie, Robert A; Whitehead, Simon; Morrison, Paul; Marriott, Philip J

2006-10-13

336

EVALUATION OF GEL PERMEATION CHROMATOGRAPHY FOR CLEAN UP OF HUMAN ADIPOSE TISSUE SAMPLES FOR GC/MS ANALYSIS OF PESTICIDES AND OTHER CHEMICALS  

EPA Science Inventory

Gel permeation chromatography (GPC) has been evaluated for clean up of human adipose tissue sample extracts in preparation for confirmatory analysis by gas chromatography-mass spectrometry (GC/MS). Studies were conducted with standard solutions, fortified chicken fat, and actual ...

337

Analysis of butadiene, butadiene monoxide, and butadiene dioxide in blood by gas chromatography/gas chromatography/mass spectroscopy.  

PubMed

A new method was developed to quantify the levels of 1,3-butadiene (BD), butadiene monoxide (BDO), and butadiene diepoxide (BDO2) in blood. The method was based on vacuum distillation of tissues followed by analysis of the distillates using multidimensional GC/MS. Metabolites isolated from blood by vacuum distillation were condensed into a cold trap. After warming the traps to room temperature, BD and BDO were sampled from the trap vapor phase. BDO2 was extracted from the codistilled water phase using ethyl acetate. Samples were analyzed using a multidimensional GC system equipped with a custom-built interface. The method was validated by analysis of 0.75-mL aliquots of mouse blood spiked with 5.0, 3.4, and 0.55 nmol of BD, BDO, and BDO2, respectively. The recoveries of analytes were 96 +/- 18%, 125 +/- 15%, and 98 +/- 12%, respectively (mean +/- SD, n = 6). Kinetic studies indicated no loss of BDO and BDO2 in blood held at room temperature in closed containers for up to 1 h. The method was applied to blood samples from B6C3F1 mice and Sprague-Dawley rats exposed by inhalation (nose-only) to 100 ppm BD for 4 h. Blood levels of BD and BDO in exposed rats were 4.1 +/- 1.0 and 0.10 +/- 0.06 microM, respectively (mean +/- SD, n = 6). Levels of BDO2 were below the limits of detection (0.01 nmol/mL). Blood levels of BD, BDO, and BDO2 in mice exposed to 100 ppm BD for 4 h were 2.9 +/- 1.3, 0.38 +/- 0.14, and 0.33 +/- 0.19 microM, respectively (mean +/- SD, n = 6).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7766800

Bechtold, W E; Strunk, M R; Thornton-Manning, J R; Henderson, R F

1995-03-01

338

A comparison of the validity of gas chromatography- mass spectrometry and liquid chromatography- tandem mass spectrometry analysis of urine samples for morphine, codeine, 6-acetylmorphine, and benzoylecgonine.  

PubMed

On November 25, 2008, the U.S. Department of Health and Human Services posted a final notice in the Federal Register authorizing the use of liquid chromatography-tandem mass spectrometry (LC-MS-MS) and other technologies in federally regulated workplace drug testing (WPDT) programs. These rules are expected to become effective in May 2010. To support this change, it is essential to explicitly demonstrate that LC-MS-MS as a technology can produce results at least as valid as gas chromatography-mass spectrometry (GC-MS), the long-accepted standard in confirmatory analytical technologies for drugs of abuse and currently the only confirmatory method allowed for use in support of federally regulated WPDT programs. A series of manufactured control urine samples (n = 10 for each analyte) containing benzoylecgonine, morphine, codeine, and 6-acetylmorphine at concentrations ranging from 10% to 2000% of federal cutoffs were analyzed with replication by five federally regulated laboratories using GC-MS (five replicate analyses per lab) and at RTI International using LC-MS-MS (10 replicate analyses). Interference samples as described in the National Laboratory Certification Program 2009 Manual were also analyzed by both GC-MS and LC-MS-MS. In addition, matrix effects were assessed for LC-MS-MS, and both analytical technologies were used to analyze previously confirmed urine specimens of WPDT origin. Results indicated that LC-MS-MS analysis produced results at least as precise, accurate, and specific as GC-MS for the analytes investigated in this study. Matrix effects, while evident, could be controlled by the use of matrix-matched controls and calibrators with deuterated internal standards. LC-MS-MS data parameters, such as retention time and product ion ratios, were highly reproducible. PMID:19874645

Stout, Peter R; Bynum, Nichole D; Mitchell, John M; Baylor, Michael R; Ropero-Miller, Jeri D

2009-10-01

339

Direct pharmacokinetic analysis of puqietinone by in vivo microdialysis sampling and turbulent-flow chromatography coupled with liquid chromatography-mass spectrometry.  

PubMed

Sample pretreatment is a key step in bioanalytical process because of possible interference and matrix effects in mass spectrometry analysis. In this work, a novel strategy towards high speed and sensitivity was developed combining in vivo microdialysis (MD) sampling, turbulent-flow chromatography (TFC), and liquid chromatography-mass spectrometry (LC-MS). The procedures of cleanup, preconcentration, and separation were completed on-line in one step within 10min. During the MD optimization procedure, 1% hydroxypropyl-?-cyclodextrin (HP-?-CD) was used to improve the relative recovery of the analyte. Untreated MD samples were directly injected, and a TFC precolumn was flushed for 1min with aqueous phase of 4mL/min flow rate to desalt and concentrate biosamples. The retained analytes were then back-flushed by a switching valve onto a fast LC column (4.6mm×50mm, 1.8?m) for separation. Another diverter valve was employed to prevent the HP-?-CD that interferes with the ESI process from entering the MS. Puqietinone, a lipophilic alkaloid from Fritillaria puqiensis, was used as a case for validation. Results showed that the limit of quantification for puqietinone was 0.10ng/mL, and good linearity (R(2)=0.9993) was maintained over the range of 1.02-200.02ng/mL. Accuracy and precision were satisfactory within the range of the standard curve. This approach was able to effectively eliminate the influences of matrix effect and carry-over as the injection volume increased up to 20?L. The developed method was successfully applied to pharmacokinetic study of puqietinone after intravenous administration to rat. Results demonstrate the potential of using MD with TFC-LC/MS for in vivo monitoring experiments. PMID:22658466

Xin, Gui-Zhong; Cao, Liu; Shi, Zi-Qi; Li, Hui-Jun; Wen, Xiao-Dong; Chen, Jun; Qi, Lian-Wen; Li, Ping

2012-06-15

340

Qualitative and quantitative analysis of pyrolysis oil by gas chromatography with flame ionization detection and comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry.  

PubMed

Pyrolysis oils have attracted a lot of interest, as they are liquid energy carriers and general sources of chemicals. In this work, gas chromatography with flame ionization detector (GC-FID) and two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS) techniques were used to provide both qualitative and quantitative results of the analysis of three different pyrolysis oils. The chromatographic methods and parameters were optimized and solvent choice and separation restrictions are discussed. Pyrolysis oil samples were diluted in suitable organic solvent and were analyzed by GC×GC-TOFMS. An average of 300 compounds were detected and identified in all three samples using the ChromaToF (Leco) software. The deconvoluted spectra were compared with the NIST software library for correct matching. Group type classification was performed by use of the ChromaToF software. The quantification of 11 selected compounds was performed by means of a multiple-point external calibration curve. Afterwards, the pyrolysis oils were extracted with water, and the aqueous phase was analyzed both by GC-FID and, after proper change of solvent, by GC×GC-TOFMS. As previously, the selected compounds were quantified by both techniques, by means of multiple point external calibration curves. The parameters of the calibration curves were calculated by weighted linear regression analysis. The limit of detection, limit of quantitation and linearity range for each standard compound with each method are presented. The potency of GC×GC-TOFMS for an efficient mapping of the pyrolysis oil is undisputable, and the possibility of using it for quantification as well has been demonstrated. On the other hand, the GC-FID analysis provides reliable results that allow for a rapid screening of the pyrolysis oil. To the best of our knowledge, very few papers have been reported with quantification attempts on pyrolysis oil samples using GC×GC-TOFMS most of which make use of the internal standard method. This work provides the ground for further analysis of pyrolysis oils of diverse sources for a rational design of both their production and utilization process. PMID:21036362

Sfetsas, Themistoklis; Michailof, Chrysa; Lappas, Angelos; Li, Qiangyi; Kneale, Brian

2011-05-27

341

Targeted liquid chromatography–mass spectrometry analysis of serum acylcarnitines in acetaminophen toxicity in children  

PubMed Central

Aim Long-chain acylcarnitines have been postulated to be sensitive biomarkers of acetaminophen (APAP)-induced hepatotoxicity in mouse models. In the following study, the relationship of acylcarnitines with other known indicators of APAP toxicity was examined in children receiving low-dose (therapeutic) and high-dose (‘overdose’ or toxic ingestion) exposure to APAP. Materials & methods The study included three subject groups: group A (therapeutic dose, n = 187); group B (healthy controls, n = 23); and group C (overdose, n = 62). Demographic, clinical and laboratory data were collected for each subject. Serum samples were used for measurement of APAP protein adducts, a biomarker of the oxidative metabolism of APAP and for targeted metabolomics analysis of serum acylcarnitines using ultra performance liquid chromatography–triple-quadrupole mass spectrometry. Results Significant increases in oleoyl- and palmitoyl-carnitines were observed with APAP exposure (low dose and overdose) compared with controls. Significant increases in serum ALT, APAP protein adducts and acylcarnitines were observed in overdose children that received delayed treatment (time to treatment from overdose >24 h) with the antidote N-acetylcysteine. Time to peak APAP protein adducts in serum was shorter than that of the acylcarnitines and serum ALT. Conclusion Perturbations in long-chain acylcarnitines in children with APAP toxicity suggest that mitochrondrial injury and associated impairment in the ?-oxidation of fatty acids are clinically relevant as biomarkers of APAP toxicity. PMID:24521011

Bhattacharyya, Sudeepa; Yan, Ke; Pence, Lisa; Simpson, Pippa M; Gill, Pritmohinder; Letzig, Lynda G; Beger, Richard D; Sullivan, Janice E; Kearns, Gregory L; Reed, Michael D; Marshall, James D; Van Den Anker, John N; James, Laura P

2014-01-01

342

Liquid chromatography-mass spectrometry analysis of diethylcarbamazine in human plasma for clinical pharmacokinetic studies.  

PubMed

A sensitive and selective liquid chromatographic method using mass spectrometric detection was developed for the determination of diethylcarbamazine (DEC) in human plasma. DEC and its stable isotope internal standard d3-DEC were extracted from 0.25mL of human plasma using solid phase extraction. Chromatography was performed using a Phenomenex Synergi 4? Fusion-RP column (2mm×250mm) with gradient elution. The retention time was approximately 4.8min. The assay was linear from 4 to 2200ng/mL. Analysis of quality control samples at 12, 300, and 1700ng/mL (N=15) had interday coefficients of variation of 8.4%, 5.4%, and 6.2%, respectively (N=15). Interday bias results were -2.2%, 6.0%, and 0.8%, respectively. Recovery of DEC from plasma ranged from 84.2% to 90.1%. The method was successfully applied to clinical samples from patients with lymphatic filariasis from a drug-drug interaction study between DEC and albendazole and/or ivermectin. PMID:24975211

Schmidt, Mark S; King, Christopher L; Thomsen, Edward K; Siba, Peter M; Sanuku, Nelly; Fleckenstein, Lawrence

2014-09-01

343

Optimised determination of clobazam in human plasma with extraction and high-performance liquid chromatography analysis.  

PubMed

The analysis of clobazam by high-performance liquid chromatography and UV detection is described herein. After adding an internal standard, 600 microl of plasma were extracted under basic conditions onto disposable cartridges packed with celite. The organic extract was then evaporated to dryness and the residue reconstituted in 200 microl of mobile phase. A 20 microl aliquot was injected into chromatograph. The HPLC system was equipped with an Ultrasphere C8 analytical column coupled with an UV detector set at 235 nm. The mobile phase was an acetate buffer 20 mM, pH 5.5, containing acetonitrile and triethylamine 70:30:0.01 (v/v); the flow-rate was 1.8 ml/min. Using this method, clobazam can be detected with a sensitivity limit of 6 ng/ml and the RSD% intra- and inter-assay were lower than 5%. For its ruggedness and reliability, the proposed method is particularly suitable for therapeutic drug monitoring in epilepsy. PMID:11204219

Bolner, A; Tagliaro, F; Lomeo, A

2001-01-01

344

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

PubMed

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

Cajka, Tomas; Fiehn, Oliver

2014-10-01

345

Enrichment of Integral Membrane Proteins for Proteomic Analysis Using Liquid Chromatography-Tandem Mass Spectrometry  

SciTech Connect

Currently, most proteomic studies rely on liquid chromatography-tandem mass spectrometry (LC-MS/MS) to detect and identify constituent peptides of enzymatically digested proteins obtained from various organisms and cell types. However, sample preparation methods for isolating membrane proteins typically involve the use of detergents, chaotropes, or reducing reagents that often interfere with electrospray ionization (ESI). To increase the identification of integral membrane proteins by LC-ESI-MS/MS, a sample preparation method combining carbonate extraction and surfactant-free organics solvent-assisted solubilization and proteolysis was developed and used to target the membrane subproteome of Deinococcus radiodurans. Out of 503 proteins identified, 135 were recognized as hydrophobic based on their positive grand average of hydropathicity values that covers 15% of the theoretical hydrophobic proteome. Using the PSORT algorithm, 268 identified proteins were recognized as integral membrane proteins covering 21% and 43% of the predicted integral cytoplasmic and outer membrane proteins, respectively. Of the integral cytoplasmic membrane proteins containing four or more predicted transmembrane domains (TMDs), 65% were identified by detecting at least one peptide spanning a TMD using LC-MS/MS. The extensive identification of highly hydrophobic proteins containing multiple TMDs confirms the efficacy of the described sample preparation protocol to isolate and solubilize integral membrane proteins and validates the method for large-scale analysis of bacterial membrane subproteomes using LC-ESI-MS/MS.

Blonder, Josip; Goshe, Michael B.; Moore, Ronald J.; Pasa-Tolic, Liljiana; Masselon, Christophe D.; Lipton, Mary S.; Smith, Richard D.

2002-04-01

346

Size exclusion chromatography/mass spectrometry applied to the analysis of polysaccharides.  

PubMed

A novel method for analysing polysaccharide materials is described which employs size-exclusion chromatography (SEC) followed by detection by on-line electrospray ionisation mass spectrometry (ESI-MS) and off-line matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS). It is demonstrated through SEC/ESI ion trap mass spectrometry that the formation of multiply charged oligomer ions, which bind up to five sodium cations, allows the rapid analysis of polysaccharide ions with molecular weights in excess of 9 kDa. MALDI spectra generated from fractionation of the effluent collected from the same SEC separation are shown to be in good agreement with the ESI spectra with respect to molecular weight distributions and types of ions generated. ESI and MALDI mass spectra of samples obtained from sequential graded ethanol precipitation and SEC fractionation of acid and enzymatically digested arabinoxylan polysaccharides show important structural differences between polysaccharide fragments. In addition, a comparison is made between the mass spectra of native and permethylated SEC-separated fragments of acid and enzymatically treated arabinogalactan. Linkage information of the permethylated arabinogalactan oligomers can be rapidly established through the use of on-line SEC/ESI-MS( n) experiments. PMID:11746893

Deery, M J; Stimson, E; Chappell, C G

2001-01-01

347

Irreversible and reversible reactive chromatography: Analytical solutions and moment analysis for rectangular pulse injections.  

PubMed

This work is concerned with the analysis of models for linear reactive chromatography describing irreversible A?B and reversible A?B reactions. In contrast to previously published results rectangular reactant pulses are injected into initially empty or pre-equilibrated columns assuming both Dirichlet and Danckwerts boundary conditions. The models consist of two partial differential equations, accounting for convection, longitudinal dispersion and first order chemical reactions. Due to the effect of involved mechanisms on solute transport, analytical and numerical solutions of the models could be helpful to understand, design and optimize chromatographic reactors. The Laplace transformation is applied to solve the model equations analytically for linear adsorption isotherms. Statistical temporal moments are derived from solutions in the Laplace domain. Analytical results are compared with numerical predictions generated using a high-resolution finite volume scheme for two sets of boundary conditions. Several case studies are carried out to analyze reactive liquid chromatographic processes for a wide range of mass transfer and reaction kinetics. Good agreements in the results validate the correctness of the analytical solutions and accuracy of the proposed numerical algorithm. PMID:25670415

Bibi, Sameena; Qamar, Shamsul; Seidel-Morgenstern, Andreas

2015-03-13

348

Systematic optimization of long gradient chromatography mass spectrometry for deep analysis of brain proteome.  

PubMed

The development of high-resolution liquid chromatography (LC) is essential for improving the sensitivity and throughput of mass spectrometry (MS)-based proteomics. Here we present systematic optimization of a long gradient LC-MS/MS platform to enhance protein identification from a complex mixture. The platform employed an in-house fabricated, reverse-phase long column (100 ?m × 150 cm, 5 ?m C18 beads) coupled to Q Exactive MS. The column was capable of achieving a peak capacity of ?700 in a 720 min gradient of 10-45% acetonitrile. The optimal loading level was ?6 ?g of peptides, although the column allowed loading as many as 20 ?g. Gas-phase fractionation of peptide ions further increased the number of peptide identification by ?10%. Moreover, the combination of basic pH LC prefractionation with the long gradient LC-MS/MS platform enabled the identification of 96?127 peptides and 10?544 proteins at 1% protein false discovery rate in a post-mortem brain sample of Alzheimer's disease. Because deep RNA sequencing of the same specimen suggested that ?16?000 genes were expressed, the current analysis covered more than 60% of the expressed proteome. Further improvement strategies of the LC/LC-MS/MS platform were also discussed. PMID:25455107

Wang, Hong; Yang, Yanling; Li, Yuxin; Bai, Bing; Wang, Xusheng; Tan, Haiyan; Liu, Tao; Beach, Thomas G; Peng, Junmin; Wu, Zhiping

2015-02-01

349

Liquid Chromatography-Tandem Mass Spectrometry for Analysis of Intestinal Permeability of Loperamide in Physiological Buffer  

PubMed Central

Analysis of in vitro samples with high salt concentrations represents a major challenge for fast and specific quantification with liquid chromatography-tandem mass spectrometry (LC-MS/MS). To investigate the intestinal permeability of opioids in vitro employing the Ussing chamber technique, we developed and validated a fast, sensitive and selective method based on LC–MS/MS for the determination of loperamide in HEPES-buffered Ringer's solution. Chromatographic separation was achieved with an Atlantis dC18 column, 2.1 mm×20 mm, 3 µm particle size and a gradient consisting of methanol/0.1% formic acid and ammonium acetate. The flow rate was 0.7 ml/min, and the total run time was 3 min. For quantification, two mass transitions for loperamide and a deuterated internal standard (methadone-d3) were used. The lower limit of loperamide quantification was 0.2 ng/ml. This new LC-MS/MS method can be used for the detection of loperamide in any experimental setup using HEPES-buffered Ringer's solution as a matrix compound. PMID:23144895

Rubelt, Miriam S.; Amasheh, Salah; Grobosch, Thomas; Stein, Christoph

2012-01-01

350

Ultra-performance convergence chromatography (UPC²) method for the analysis of biogenic amines in fermented foods.  

PubMed

A rapid ultra-performance convergence chromatography (UPC(2)) method for the determination of eight biogenic amines (spermine, spermidine, putrescine, cadaverine, tryptamine, phenylethylamine, histamine and tyramine) in fermented foods was developed. The amines were pre-column derivatized with dansyl chloride and separated on UPC(2) system with a HSS C18 SB column (3.0 × 100 mm, 1.8 ?m) using gradient elution with a binary system of CO2 and n-hexane:isopropanol:ammonium hydroxide (70:30:0.15, v/v/v), back pressure of 2,000 psi, flow rate of 2.0 ml/min and DAD detection at 254 nm. The result showed excellent linearity (r=0.9995-1.0000). Limits of detection (LOD) and limits of quantification (LOQ) were 21-67 ng/L and 72-224 ng/L, respectively. Relative standard deviations (RSD) for repeatability and reproducibility were 0.21-0.87% and 1.98-4.02%, respectively. Furthermore, this method was successfully applied to analysis of biogenic amines in Yulu and Sufu samples. PMID:24874373

Gong, Xiao; Qi, Ningli; Wang, Xiaoxi; Lin, Lijing; Li, Jihua

2014-11-01

351

Quantitative analysis of mitragynine in human urine by high performance liquid chromatography-tandem mass spectrometry.  

PubMed

Mitragynine is the primary active alkaloid extracted from the leaves of Mitragyna speciosa Korth, a plant that originates in South-East Asia and is commonly known as kratom in Thailand. Kratom has been used for many centuries for their medicinal and psychoactive qualities, which are comparable to that of opiate-based drugs. Kratom abuse can lead to a detectable content of mitragynine residue in urine. Ultra trace amount of mitragynine in human urine was determined by a high performance liquid chromatography coupled to an electrospray tandem mass spectrometry (HPLC-ESI/MS/MS). Mitragynine was extracted by methyl t-butyl ether (MTBE) and separated on a HILIC column. The ESI/MS/MS was accomplished using a triple quadrupole mass spectrometer in positive ion detection and multiple reactions monitoring (MRM) mode. Ajmalicine, a mitragynine's structure analog was selected as internal standard (IS) for method development. Quality control (QC) performed at three levels 0.1, 1 and 5 ng/ml of mitragynine in urine gave mean recoveries of 90, 109, and 98% with average relative standard deviation of 22, 12 and 16%, respectively. The regression linearity of mitragynine calibration ranged from 0.01 to 5.0 ng/ml was achieved with correlation coefficient greater than 0.995. A detection limit of 0.02 ng/ml and high precision data within-day and between days analysis were obtained. PMID:19577523

Lu, Shijun; Tran, Buu N; Nelsen, Jamie L; Aldous, Kenneth M

2009-08-15

352

A high performance gel filtration chromatography method for gamma-glutamyltransferase fraction analysis.  

PubMed

The clinical relevance of serum gamma-glutamyltransferase (GGT) activity, in areas other than hepatic function, has recently been increased by several epidemiological associations. Still, GGT remains a nonspecific test because of the influence of various pathophysiological factors. We devised a procedure based on gel filtration chromatography, followed by postcolumn injection of fluorescent GGT substrate (gamma-glutamyl-7-amido-4-methylcoumarin), permitting the quantification of GGT fractions in serum or plasma. Plasma GGT molecular weight distribution was analyzed in healthy volunteers (20 males; mean+/-SD age 38+/-10 years; 20 females; age 44+/-13; total GGT 21+/-11 for males vs 13+/-7 for females; P<0.01). The method is highly sensitive (determination limit: 0.5 U GGT/L), with a linear dynamic range between 0.5 and 150 U/L for each fraction. Four GGT fractions of different molecular weight were detected in all subjects of both genders: b-GGT, m-GGT, s-GGT (likely lipoprotein-bound, molecular masses >2000, 940, and 140kDa, respectively), and a free fraction (f-GGT, 70kDa). f-GGT and s-GGT were the main fractions in subjects with lower and higher total GGT activity, respectively. Higher total GGT activity in males is related mainly to f-GGT (P<0.01). GGT fraction analysis may increase the sensitivity and specificity of the GGT activity test. PMID:18023410

Franzini, Maria; Bramanti, Emilia; Ottaviano, Virginia; Ghiri, Emiliano; Scatena, Fabrizio; Barsacchi, Renata; Pompella, Alfonso; Donato, Luigi; Emdin, Michele; Paolicchi, Aldo

2008-03-01

353

Advanced proteomic liquid chromatography  

SciTech Connect

Liquid chromatography coupled with mass spectrometry is the predominant platform used to analyze proteomics samples consisting of large numbers of proteins and their proteolytic products (e.g., truncated polypeptides) and spanning a wide range of relative concentrations. This review provides an overview of advanced capillary liquid chromatography techniques and methodologies that greatly improve separation resolving power and proteomics analysis coverage, sensitivity, and throughput.

Xie, Fang; Smith, Richard D.; Shen, Yufeng

2012-10-26

354

ANALYSIS OF HAZARDOUS WASTE AND ENVIRONMENTAL EXTRACTS BY CAPILLARY GAS CHROMATOGRAPHY/FOURIER TRANSFORM INFRARED SPECTROMETRY AND CAPILLARY GAS CHROMATOGRAPHY/MASS SPECTROMETRY  

EPA Science Inventory

The relative sensitivities of fused-silica capillary column gas chromatography/Fourier transform infrared spectrometry (FSCC/GC/FT-IR) versus packed-column GC/FT-IR and FSCC/GC/FT-IR versus fused-silica capillary column gas chromatography/mass spectrometry (FSCC/GC/MS) were compa...

355

Reliable peak selection for multisample analysis with comprehensive two-dimensional chromatography  

Technology Transfer Automated Retrieval System (TEKTRAN)

Comprehensive two-dimensional chromatography is a powerful technology for analyzing the patterns of constituent compounds in complex samples, but matching chromatographic features across large sample sets is difficult. This paper describes a new, automated method for selecting chromatographic peaks ...

356

Analysis of aliphatic biopolymers using thermochemolysis with tetramethylammonium hydroxide (TMAH) and gas chromatography–mass spectrometry  

Microsoft Academic Search

Selected aliphatic biopolyesters (cutins, cuticles and a suberin) isolated from different plants have been analyzed using thermochemolysis with tetramethylammonium hydroxide (TMAH). This method consists of a high-temperature saponification\\/transesterification, and yields methyl esters of fatty acids and the methyl ethers of alcohols, which are subsequently analyzed by gas chromatography and gas chromatography–mass spectrometry. The main compounds produced from the analyzed samples

Jose C. del Río; Patrick G. Hatcher

1998-01-01

357

Development of a mass transfer machine for gas/liquid operations in the absence of gravity  

NASA Astrophysics Data System (ADS)

A mass transfer machine for gas/liquid operations under low gravity was developed. It consists of two flat rotors, the inner surfaces being ribbed in radial direction. Due to the rotation of the machine, the liquid introduced in the center, is repeatedly dispersed on the edges of the ribs, which are arranged in series. Transport, dispersion and separation of liquid and gas are effected by centrifugal forces. The fluid dynamics were investigated for countercurrent, transition and cocurrent flow. The mass transfer investigations were carried out by desorption of CO2 from water into air. The machine is well suited for air cleaning in spacecraft or submarine labs.

Brauer, H.; Gaebelein, W.

1984-07-01

358

Time-dependent gas-liquid interaction in molecular-sized nanopores.  

PubMed

Different from a bulk phase, a gas nanophase can have a significant effect on liquid motion. Herein we report a series of experimental results on molecular behaviors of water in a zeolite ? of molecular-sized nanopores. If sufficient time is provided, the confined water molecules can be "locked" inside a nanopore; otherwise, gas nanophase provides a driving force for water "outflow". This is due to the difficult molecular site exchanges and the relatively slow gas-liquid diffusion in the nanoenvironment. Depending on the loading rate, the zeolite ?/water system may exhibit either liquid-spring or energy-absorber characteristics. PMID:25293525

Sun, Yueting; Li, Penghui; Qiao, Yu; Li, Yibing

2014-01-01

359

An Effective Device for Gas–Liquid Oxygen Removal in Enclosed Microalgae Culture  

Microsoft Academic Search

A high-performance gas–liquid transmission device (HPTD) was described in this paper. To investigate the HPTD mass transfer\\u000a characteristics, the overall volumetric mass transfer coefficients, $$K_{{\\\\text{La}},{\\\\text{CO}}_2 }^{\\\\text{A}} $$ for the absorption of gaseous CO2 and $$K_{{\\\\text{La}},{\\\\text{O}}_2 }^{\\\\text{D}} $$ for the desorption of dissolved O2 were determined, respectively, by titration and dissolved oxygen electrode. The mass transfer capability of carbon dioxide\\u000a was

Zhenfeng Su; Ruijuan Kang; Shaoyuan Shi; Wei Cong; Zhaoling Cai

2010-01-01

360

Time-dependent Gas-liquid Interaction in Molecular-sized Nanopores  

NASA Astrophysics Data System (ADS)

Different from a bulk phase, a gas nanophase can have a significant effect on liquid motion. Herein we report a series of experimental results on molecular behaviors of water in a zeolite ? of molecular-sized nanopores. If sufficient time is provided, the confined water molecules can be ``locked'' inside a nanopore; otherwise, gas nanophase provides a driving force for water ``outflow''. This is due to the difficult molecular site exchanges and the relatively slow gas-liquid diffusion in the nanoenvironment. Depending on the loading rate, the zeolite ?/water system may exhibit either liquid-spring or energy-absorber characteristics.

Sun, Yueting; Li, Penghui; Qiao, Yu; Li, Yibing

2014-10-01

361

Time-dependent Gas-liquid Interaction in Molecular-sized Nanopores  

PubMed Central

Different from a bulk phase, a gas nanophase can have a significant effect on liquid motion. Herein we report a series of experimental results on molecular behaviors of water in a zeolite ? of molecular-sized nanopores. If sufficient time is provided, the confined water molecules can be “locked” inside a nanopore; otherwise, gas nanophase provides a driving force for water “outflow”. This is due to the difficult molecular site exchanges and the relatively slow gas-liquid diffusion in the nanoenvironment. Depending on the loading rate, the zeolite ?/water system may exhibit either liquid-spring or energy-absorber characteristics. PMID:25293525

Sun, Yueting; Li, Penghui; Qiao, Yu; Li, Yibing

2014-01-01

362

Electrical impedance imaging in two-phase, gas-liquid flows: 1. Initial investigation  

NASA Technical Reports Server (NTRS)

The determination of interfacial area density in two-phase, gas-liquid flows is one of the major elements impeding significant development of predictive tools based on the two-fluid model. Currently, these models require coupling of liquid and vapor at interfaces using constitutive equations which do not exist in any but the most rudimentary form. Work described herein represents the first step towards the development of Electrical Impedance Computed Tomography (EICT) for nonintrusive determination of interfacial structure and evolution in such flows.

Lin, J. T.; Ovacik, L.; Jones, O. C.

1991-01-01

363

Drug quality assessment methods. I. Gas-liquid chromatographic assay and identification of seven barbiturates.  

PubMed

A gas-liquid chromatographic (GLC) procedure has been developed for the assay and identification of amobarbital, butabarbital, heptabarbital, mephobarbital, pentobarbital, phenobarbital, and secobarbital in single component capsule, elixir, injectable, suppository, and tablet formulations. After extraction into chloroform from an acidified aqueous mixture of the product, the drug is eluted isothermally from a methylphenylsilicone GLC column at 210 or 240 degrees C and quantitated relative to thiamylal internal standard. Results were in good agreement with those obtained using pharmacopeial assay methods. The method is suitable for the rapid assessment of commercial formulations. PMID:7130075

Black, D B; Kolasinski, H; Lovering, E G; Watson, J R

1982-09-01

364

The analysis of aqueous mixtures using liquid chromatography-electrospray mass spectrometry  

SciTech Connect

The focus of this dissertation is the use of chromatographic methods coupled with electrospray mass spectrometry (ES-MS) for the determination of both organic and inorganic compounds in aqueous solutions. The combination of liquid chromatography (LC) methods and ES-MS offers one of the foremost methods for determining compounds in complex aqueous solutions. In this work, LC-ES-MS methods are devised using ion exclusion chromatography, reversed phase chromatography, and ion exchange chromatography, as well as capillary electrophoresis (CE). For an aqueous sample, these LC-ES-MS and CE-ES-MS techniques require no sample preparation or analyte derivatization, which makes it possible to observe a wide variety of analytes as they exist in solution. The majority of this work focuses on the use of LC-ES-MS for the determination of unknown products and intermediates formed during electrochemical incineration (ECI), an experimental waste remediation process. This report contains a general introduction to the project and the general conclusions. Four chapters have been removed for separate processing. Titles are: Chapter 2: Determination of small carboxylic acids by ion exclusion chromatography with electrospray mass spectrometry; Chapter 3: Electrochemical incineration of benzoquinone in aqueous media using a quaternary metal oxide electrode in the absence of a soluble supporting electrolyte; Chapter 4: The determination of electrochemical incineration products of 4-chlorophenol by liquid chromatography-electrospray mass spectrometry; and Chapter 5: Determination of small carboxylic acids by capillary electrophoresis with electrospray mass spectrometry.

Johnson, S.

1999-02-12

365

Rapid method for hydrocarbon-type analysis of heavy oils and synthetic fuels by pyrolysis thin layer chromatography  

Microsoft Academic Search

This work describes a rapid method for hydrocargon-type analysis applying thin layer chromatography (TLC) to the pentane-soluble fraction *malthenes) of the petroleum and synthetic fuels boiling above 200°C. The principal component types encountered in this paper are saturates (SA), aromatics (AR), (mono and di together) polynuclear aromatics (PNA) and polar material (PO). The method uses a Iatroscan TLC pyrolyzer which

M. A. Poirier; A. E. George

1982-01-01

366

Sensitive analysis of 1?,25-dihydroxyvitamin D 3 in biological fluids by liquid chromatography–tandem mass spectrometry  

Microsoft Academic Search

A liquid chromatographic–tandem mass spectrometric assay using 5% bovine serum albumin as the calibration matrix has been developed for the quantitative analysis of 1?,25-dihydroxyvitamin D3 [1?,25(OH)2D3] in biological fluids. The analyte was extracted from the matrix after protein precipitation using an automated solid-phase extraction procedure involving both a reversed-phase and normal-phase procedure on a single C18 cartridge. The analytical chromatography

Anne-Marie Kissmeyer; Kim Sonne

2001-01-01

367

Simulated distillation of high-boiling petroleum fractions by capillary supercritical fluid chromatography and vacuum thermal gravimetric analysis  

Microsoft Academic Search

Capillary supercritical fluid chromatography (SFC) and vacuum thermal gravimetric analysis (VTGA) were utilized for simulated distillation (SIMDIS) of high-boiling petroleum fractions obtained by short-path vacuum distillation. The SFC method covers the approximate boiling range of 250-1400°F. Under the present conditions, even 42% of a nondistillable, nondeasphalted residue was recovered from the column at a calculated 1426°F atmospheric equivalent boiling point.

Herbert E. Schwartz; Robert G. Brownlee; Mieczyslaw M. Boduszynski; Fu. Su

1987-01-01

368

Molecular analysis of intact preen waxes of Calidris canutus (Aves: Scolopacidae) by gas chromatography\\/mass spectrometry  

Microsoft Academic Search

The intact preen wax esters of the red knot Calidris canutus were studied with gas chromatography\\/mass spectrometry (GC\\/MS) and GC\\/MS\\/MS. In this latter technique, transitions from the\\u000a molecular ion to fragment ions representing the fatty acid moiety of the wax esters were measured, providing additional resolution\\u000a to the analysis of wax esters. The C21?C32 wax esters are composed of complex

Marlèn H. A. Dekker; Theunis Piersma; Jaap S. Sinninghe Damsté

2000-01-01

369

Fast pesticide multiresidue analysis in American ginseng ( Panax quinquefolium L.) by gas chromatography with electron capture detection  

Microsoft Academic Search

A fast pesticide multiresidue analysis method using gas chromatography coupled with electron capture detector was investigated\\u000a for the simultaneous determination of 15 organochlorine pesticides (OCPs) in American ginseng (Panax quinquefolium L.). Samples were extracted with acetic acid–water–acetonitrile (1:5:94, v\\/v) and cleaned up by the Quick Easy Cheap Effective\\u000a Rugged and Safe multiresidue method (QuEChERS). The linearity for 15 OCPs, in

Jianwei Wu; Yougang Liu; Runhuai Zhao; Rong Xu

2011-01-01

370

Analysis of phenoxyacetic acid herbicides as biomarkers in human urine using liquid chromatography\\/triple quadrupole mass spectrometry  

Microsoft Academic Search

Phenoxyacetic acids are widely used herbicides. The toxicity of phenoxyacetic acids is debated, but high-level exposure has been shown to be hepatotoxic as well as nephrotoxic in animal studies. An inter-species difference in toxic effects has been found, with dogs particularly susceptible. In this study a method using liquid chromatography\\/triple quadrupole mass spectrometry (LC\\/MS\\/MS) is described for the analysis of

Christian H. Lindh; Margareta Littorin; Asa Amilon; Bo A. G. Jonsson

2008-01-01

371

Validation of the analysis of the 15+1 European-priority polycyclic aromatic hydrocarbons by donnor-acceptor complex chromatography and high-performance liquid chromatography-ultraviolet/fluorescence detection.  

PubMed

The European Commission recommends to monitor the 16 polycyclic aromatic hydrocarbons (PAHs) possessing both genotoxic and carcinogenic properties. Since robust analytical methods specific for this set of European PAH are lacking, a new method for their analysis in food is proposed. The donnor-acceptor complex chromatography (DACC) is used as clean-up step and high-performance liquid chromatography-ultraviolet/fluorescence detection (HPLC-UV/FLD) is used for detection and quantification. The method has been validated for analysis of PAH in oil and in dried plants and bears very good results for all compounds. PMID:18951551

Windal, I; Boxus, L; Hanot, V

2008-11-28

372

Analysis of eight capsaicinoids in peppers and pepper-containing foods by high-performance liquid chromatography and liquid chromatography-mass spectrometry.  

PubMed

Diverse procedures have been reported for the isolation and analysis of secondary metabolites called capsaicinoids, pungent compounds in the fruit of the Capsicum (Solanaceae) plant. To further improve the usefulness of high-performance liquid chromatography (HPLC), studies were carried out on the analysis of extracts containing up to eight of the following capsaicinoids: capsaicin, dihydrocapsaicin, homocapsaicin-I, homocapsaicin-II, homodihydrocapsaicin-I, homodihydrocapsaicin-II, nonivamide, and nordihydrocapsaicin. HPLC was optimized by defining effects on retention times of (a) the composition of the mobile phase (acetonitrile/0.5% formic acid in H2O), (b) the length of the Inertsil column, and (c) the capacity values (k) of the column packing. Identification was based on retention times and mass spectra of individual peaks. Quantification was based on the UV response at 280 nm in HPLC and recoveries from spiked samples. The method (limit of detection of approximately 15-30 ng) was successfully used to quantify capsaicinoid levels of parts of the pepper fruit (pericarp, placenta, seeds, and in the top, middle, and base parts of whole peppers) in 17 species of peppers and in 23 pepper-containing foods. The results demonstrate the usefulness of the method for the analysis of capsaicinoids ranging from approximately 0.5 to 3600 microg of capsaicin equiv/g of product. The water content of 12 fresh peppers ranged from 80.8 to 92.7%. The described freeze-drying, extraction, and analysis methods should be useful for assessing the distribution of capsaicinoids in the foods and in defining the roles of these biologically active compounds in the plant, the diet, and medicine. PMID:16277419

Kozukue, Nobuyuki; Han, Jae-Sook; Kozukue, Etsuko; Lee, Sin-Jung; Kim, Joung-Ae; Lee, Kap-Rang; Levin, Carol E; Friedman, Mendel

2005-11-16

373

Cellular lipid extraction for targeted stable isotope dilution liquid chromatography-mass spectrometry analysis.  

PubMed

The metabolism of fatty acids, such as arachidonic acid (AA) and linoleic acid (LA), results in the formation of oxidized bioactive lipids, including numerous stereoisomers(1,2). These metabolites can be formed from free or esterified fatty acids. Many of these oxidized metabolites have biological activity and have been implicated in various diseases including cardiovascular and neurodegenerative diseases, asthma, and cancer(3-7). Oxidized bioactive lipids can be formed enzymatically or by reactive oxygen species (ROS). Enzymes that metabolize fatty acids include cyclooxygenase (COX), lipoxygenase (LO), and cytochromes P450 (CYPs)(1,8). Enzymatic metabolism results in enantioselective formation whereas ROS oxidation results in the racemic formation of products. While this protocol focuses primarily on the analysis of AA- and some LA-derived bioactive metabolites; it could be easily applied to metabolites of other fatty acids. Bioactive lipids are extracted from cell lysate or media using liquid-liquid (l-l) extraction. At the beginning of the l-l extraction process, stable isotope internal standards are added to account for errors during sample preparation. Stable isotope dilution (SID) also accounts for any differences, such as ion suppression, that metabolites may experience during the mass spectrometry (MS) analysis(9). After the extraction, derivatization with an electron capture (EC) reagent, pentafluorylbenzyl bromide (PFB) is employed to increase detection sensitivity(10,11). Multiple reaction monitoring (MRM) is used to increase the selectivity of the MS analysis. Before MS analysis, lipids are separated using chiral normal phase high performance liquid chromatography (HPLC). The HPLC conditions are optimized to separate the enantiomers and various stereoisomers of the monitored lipids(12). This specific LC-MS method monitors prostaglandins (PGs), isoprostanes (isoPs), hydroxyeicosatetraenoic acids (HETEs), hydroxyoctadecadienoic acids (HODEs), oxoeicosatetraenoic acids (oxoETEs) and oxooctadecadienoic acids (oxoODEs); however, the HPLC and MS parameters can be optimized to include any fatty acid metabolites(13). Most of the currently available bioanalytical methods do not take into account the separate quantification of enantiomers. This is extremely important when trying to deduce whether or not the metabolites were formed enzymatically or by ROS. Additionally, the ratios of the enantiomers may provide evidence for a specific enzymatic pathway of formation. The use of SID allows for accurate quantification of metabolites and accounts for any sample loss during preparation as well as the differences experienced during ionization. Using the PFB electron capture reagent increases the sensitivity of detection by two orders of magnitude over conventional APCI methods. Overall, this method, SID-LC-EC-atmospheric pressure chemical ionization APCI-MRM/MS, is one of the most sensitive, selective, and accurate methods of quantification for bioactive lipids. PMID:22127066

Gelhaus, Stacy L; Mesaros, A Clementina; Blair, Ian A

2011-01-01

374

ION CHROMATOGRAPHY  

EPA Science Inventory

The theory of ion chromatography as a technique for analyzing ionic substances is discussed. The application of ion chromatography for analyzing ambient air samples is specifically described, with emphasis on determining sulfate, nitrate, and ammonium ions in aerosols, and sulfur...

375

APPLICATIONS OF INFORMATION THEORY AND PATTERN RECOGNITION TO GAS CHROMATOGRAPHY-MASS SPECTROMETRIC ANALYSIS OF TOXIC ORGANIC COMPOUNDS IN AMBIENT AIR  

EPA Science Inventory

The number of information channels contained in the gas chromatographic, mass spectrometric, and combined gas chromatography-mass spectrometric analysis of 78 toxic organic compounds has been determined. The toxic compounds are those routinely monitored in ambient air samples usi...

376

Flow Injection Analysis and Liquid Chromatography for Multifunctional Chemical Analysis (MCA) Systems  

ERIC Educational Resources Information Center

The large class sizes of first-year chemistry labs makes it challenging to provide students with hands-on access to instrumentation because the number of students typically far exceeds the number of research-grade instruments available to collect data. Multifunctional chemical analysis (MCA) systems provide a viable alternative for large-scale…

Mayo, Ana V.; Loegel, Thomas N.; Bretz, Stacey Lowery; Danielson, Neil D.

2013-01-01

377

Acoustic tuning of gas liquid scheme injectors for acoustic damping in a combustion chamber of a liquid rocket engine  

NASA Astrophysics Data System (ADS)

In a combustion chamber of a liquid rocket engine, acoustic fine-tuning of gas-liquid scheme injectors is studied numerically for acoustic stability by adopting a linear acoustic analysis. Injector length and blockage ratio at gas inlet are adjusted for fine-tuning. First, acoustic behavior in the combustor with a single injector is investigated and acoustic-damping effect of the injector is evaluated for cold condition by the quantitative parameter of damping factor as a function of injector length. From the numerical results, it is found that the injector can play a significant role in acoustic damping when it is tuned finely. The optimum tuning-length of the injector to maximize the damping capacity corresponds to half of a full wavelength of the first longitudinal overtone mode traveling in the injector with the acoustic frequency intended for damping in the chamber. In baffled chamber, the optimum lengths of the injector are calculated as a function of baffle length for both cold and hot conditions. Next, in the combustor with numerous resonators, peculiar acoustic coupling between a combustion chamber and injectors is observed. As the injector length approaches a half-wavelength, the new injector-coupled acoustic mode shows up and thereby, the acoustic-damping effect of the tuned injectors is appreciably degraded. And, damping factor maintains a near-constant value with blockage ratio and then, decreases rapidly. Blockage ratio affects also acoustic damping and should be considered for acoustic tuning.

Sohn, Chae Hoon; Park, I.-Sun; Kim, Seong-Ku; Jip Kim, Hong

2007-07-01

378

Cluster Regime—The New Regime Of Flowing Of Gas-Liquid Mixture In Vertical Columns (Based On Experimental Data)  

NASA Astrophysics Data System (ADS)

For the revealing of the reasons of occurrence of discrete volcanic explosions of basalt magma the Complex Apparatus for Modeling Basaltic Eruptions (CAMBE) has been developed. It consists of two major systems—modeling and recording. The device is 18 meters high. During experiments gas-saturated model liquid acts from the saturator to the vertical transparent hose in which arising two-phase structures and its kinetics are studied. The experiments resulted in detecting and describing a new, never before known, mode of gas-liquid two-phase flow in a vertical column—defined here as cluster regime, which is characterized by regular alteration of dense gas bubble clusters separated from each other by the liquid not containing free gas phase. The mechanism of the cluster regime formation is conditioned by the processes of blocking of the hose working section by one big bubble or several smaller ones. It has been demonstrated that liquid, bubble, cluster and slug regime are regularly sequential and present polymorphic modifications of gas-saturated liquids migrating within vertically oriented conduits. Analysis of data on explosions at volcanoes, given the obtained experimental data on the mechanism of this process, allows concluding that realization of cluster or slug regimes in volcanic crater produces basaltic explosions.

Ozerov, A. Yu.

2010-03-01

379

Determination of interaction second virial coefficients for the CO?-H?O system using gas-liquid chromatography  

E-print Network

; 4) data should be gathered for at least five points at each isotherm; and 5) the pressure drop across the column should be min- imized. ACKNOWLEDGEMENTS I would like to thank Dr. K. R. Hall and Dr. J. C. Holste for their support, guidance.... Representative Adsorption Isotherm 2. Relationship Between Saturated Liquid Volume and Partial Molar Volume 3. Schematic Diagram of Modified GLC 12 14 Apparatus 17 4. Phase Transition Indicator 5. Extrapolation to Zero peak Area 6. Experimental Data...

Rogers, Keith Nolan

1979-01-01

380

Affinity Chromatography  

NSDL National Science Digital Library

This is an experiment showing the application of affinity chromatography to the separation of albumin from horse serum. A brief introduction of affinity chromatography and how it is being used in this specific experiment is given. This appears to be a good experiment to show the advantages of affinity chromatography in separating specific proteins from a complex matrix and would be useful in a biochemistry course or a course that is specifically looking at differing types of chromatography.

DiResta, Dan

381

Experimental study on ionic wind measurement of an electrohydrodynamically induced gas-liquid two-phase flow field by particle image velocimetry  

Microsoft Academic Search

Ionic wind of an electrohydrodynamically induced gas-liquid two-phase flow fields is experimentally measured. Since the electrohydrodynamic liquid flow motion will be created by an interrelation of ionic wind along the gas-liquid interface, new approaches are required to analyze this electrohydrodynamic gas-liquid two-phase flow type. In this work, ionic wind measurement along the stratified dielectric liquid was carried out by a

R. Honma; R. Ohyama

2000-01-01

382

Space Storable Propellant Performance Gas/Liquid Like-Doublet Injector Characterization  

NASA Technical Reports Server (NTRS)

A 30-month applied research program was conducted, encompassing an analytical, design, and experimental effort to relate injector design parameters to simultaneous attainment of high performance and component (injector/thrust chamber) compatibility for gas/liquid space-storable propellants. The gas/liquid propellant combination selected for study was FLOX (82.6% F2)/ambient temperature gaseous methane. The injector pattern characterized was the like-(self)-impinging doublet. Program effort was apportioned into four basic technical tasks: injector and thrust chamber design, injector and thrust chamber fabrication, performance evaluation testing, and data evaluation and reporting. Analytical parametric combustion analyses and cold flow distribution and atomization experiments were conducted with injector segment models to support design of injector/thrust chamber combinations for hot fire evaluation. Hot fire tests were conducted to: (1) optimize performance of the injector core elements, and (2) provide design criteria for the outer zone elements so that injector/thrust chamber compatibility could be achieved with only minimal performance losses.

Falk, A. Y.

1972-01-01

383

Gas-liquid two-phase flow through packed bed reactors in microgravity  

NASA Astrophysics Data System (ADS)

Experimental results on flow pattern transitions, pressure drop and flow characteristics for cocurrent gas-liquid flow through packed bed reactors in microgravity is presented and analyzed. The pulse flow regime is shown to exist over a much wider range of gas and liquid flow rates when under microgravity conditions. A new model is developed to predict the transition from bubble flow to pulse flow based on the dimensionless Suratman number. The Suratman number is shown to represent the balance of forces at the pore level which determine the conditions necessary for the onset of pulse flow in the column. This model is then extended to normal gravity flows in the downward direction for fixed Bond numbers. A model to predict pressure drop in the absence of gravity is also presented. An additional pressure drop term is developed to extend the applicability of the Ergun equation to gas-liquid flow. This term represents the losses resulting from the dynamic interaction between the two phases and is superposed with the liquid viscous and inertia terms to represent the total pressure loss through a reactor bed in a microgravity environment. The modified two-phase Ergun equation is shown to provide good agreement with the experimental results.

Motil, Brian Joseph

384

Evaluation of high-efficiency gas liquid contactors for natural gas processing  

SciTech Connect

The objectives of this program are to develop and evaluate advanced processing technologies that can reduce the cost of upgrading sub quality natural gas to pipeline standards. The successful application of cost-effective, new technologies will facilitate the production of sub quality natural gas that otherwise would be too expensive to produce. The overall program is focused on the following activities: evaluation of the potential of structured packing for the removal of acid gases from natural gases, and expansion of the currently available database of the fluid dynamics of rotating gas liquid contactors. The natural gas sweetening, structured packing field tests are scheduled to be conducted in calendar year 1995. Design, procurement and construction of the field test unit. Expansion of the available data base on the hydraulic characteristics of a rotating gas-liquid contactor is being pursued through a series of laboratory experiments. A 100 GPM, low pressure rotary contactor system has been assembled at IGT`s Energy Development Center to examine the fluid dynamic behavior of this type of contactor. The studies are determining the effects of liquid viscosity, liquid surface tension and operating conditions on liquid residence times and flooding limits.

Palla, N.; Lee, A.L.

1995-06-01

385

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

NASA Technical Reports Server (NTRS)

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-Cassini entry probe, which is being jointly planned by NASA and the European Space Agency (ESA), might be launched as early as 1994. As in the Pioneer mission, limited time--perhaps only 3-4 h--will be available for the completion of all analyses while the probe descends through the atmosphere. A conventional GC or GC-MS system would be able to analyze no more than two aerosol and two gas samples during the probe's descent. Conventional GC also is limited by the sensitivity of the detector and by the sample volume. For the Titan mission, the sensitivity problems will be worse because the atmospheric pressure at the time of instrument deployment is expected to be < 3 torr. Consequently, the sample volume might not be large enough to satisfy the detector sensitivity requirements. Because of such limitations, alternative GC analysis techniques have been investigated for future NASA missions. Multiplex gas chromatography has been investigated as a possible candidate for chemical analysis within a spacecraft or other restricted environment, and chemical modulators have been developed and used when needed with this technique to reduce the size and weight of the instrumentation. Also, several new multiplex techniques have been developed for use in specific applications.

Valentin, J. R.

1989-01-01

386

Volatile compounds of rehydrated French beans, bell peppers and leeks. Part II. Gas chromatography\\/sniffing port analysis and sensory evaluation  

Microsoft Academic Search

The flavours of rehydrated diced French beans, red bell peppers and leeks were characterised by gas chromatography\\/sniffing port analysis (GC\\/SP) of volatile compounds released in a mouth model system, and by descriptive sensory analysis. Volatile compounds were identified by combined gas chromatography\\/mass spectrometry. In French beans, bell peppers and leeks, respectively, 10, 16 and 22 compounds possessed detectable odours. A

Saskia M. Van Ruth; Jacques P. Roozen; Jan L. Cozijnsen; Maarten A. Posthumus

1995-01-01

387

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

USGS Publications Warehouse

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

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

2002-01-01

388

Analysis of phenolic compounds in rhubarbs using liquid chromatography coupled with electrospray ionization mass spectrometry.  

PubMed

Rhubarb is an important herbal medicine for the treatment of constipation, inflammation, and cancer. In this study, a facile method based on liquid chromatography coupled with electrospray ionization tandem mass spectrometry has been established for the analysis of bioactive phenolic compounds in rhubarbs. From six rhubarb species, official (Rheum officinale, R. palmatum, and R. tanguticum) and unofficial (R. franzenbachii, R. hotaoense, and R. emodi), a total of 107 phenolic compounds were identified or tentatively characterized based on their mass spectra. These compounds include sennosides, anthraquinones, stilbenes, glucose gallates, naphthalenes, and catechins. Ion chromatograms for the identified compounds of different rhubarbs were then compared. Consistent with previous reports, sennosides and rhein were only detected in official rhubarbs. Unexpectedly, we found that R. officinale contained very different phenolic compounds from the other two official species. Sennoside A, which has been considered as the major purgative component of rhubarb, was only detected in R. officinale, while its close isomers were observed in R. palmatum and R. tanguticum. In addition, the predominant anthraquinone glycosides in R. officinale were found to be rhein 8-O-glucoside and emodin 1-O-glucoside, whereas those in R. palmatum and R. tanguticum were rhein 1-O-glucoside and emodin 8-O-glucoside. Stilbenes, which are the major constituents of unofficial rhubarbs, were also different among the species. Our results clarify the chemical composition of rhubarbs comprehensively for the first time. Due to the significant differences in chemical components of rhubarbs, we suggest that different Rheum species be used separately in clinical practice. PMID:17029978

Ye, Min; Han, Jian; Chen, Hubiao; Zheng, Junhua; Guo, Dean

2007-01-01

389

Analysis of modified polyamide 6.6 using coupled liquid chromatography and MALDI-TOF-mass spectrometry  

NASA Astrophysics Data System (ADS)

A new approach of analysis of polyamide 6.6 using the principle of coupling polymer liquid chromatography to matrix assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS) is presented. In contrast to the known technique of two-dimensional chromatography, MALDI-TOF-MS was applied in the 2nd chromatographic dimension. According to the synthesis of polyamide 6.6 various species with different end groups are expected. Due to the capping of the end groups during the synthesis, either performed by the addition of mono-functional amines or acids, additional structures are formed and found. Although the resolution of chromatography applied for separation was poor in comparison to the broad variety of expected species, a complete identification of those components was achieved applying the MALDI-TOF-MS technique. The results were presented in a two-dimensional plot, which can be used as a fingerprint method for the analysis of polyamide 6.6.

Weidner, Steffen M.; Just, Ulrich; Wittke, Wolfgang; Rittig, Frank; Gruber, Freddy; Friedrich, Joerg F.

2004-11-01

390

Hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry for acidic herbicides and metabolites analysis in fresh water.  

PubMed

Theoretical papers and environmental applications of hydrophilic interaction liquid chromatography (HILIC) have been published for a wide range of analytes, but to our knowledge, no study focused on acidic herbicides (e.g., triketones, phenoxy acids, sulfonylurea, and acidic metabolites of chloroacetanilides). Matrix effects are the main obstacle to natural sample analysis by liquid chromatography coupled with tandem mass spectrometry (MS) via an electrospray ionization (ESI) interface. Therefore, we paid particular attention on limiting interference by (i) adapting the emerging HILIC technique, which is generally considered more sensitive than conventional reversed phase liquid chromatography and (ii) optimizing the solid phase extraction (SPE) step using a design of experiment. A rapid and reliable off line SPE-HILIC-ESI-MS/MS method was thus developed for the quantification of acidic herbicides in fresh water, with limits of quantifications (LOQs) ranging from 5 to 22 ng L(-1). Then, the analysis of freshwater samples highlighted the robustness of the method, and the importance of the chloroacetanilides metabolites among the studied analytes. PMID:24859693

Fauvelle, Vincent; Mazzella, Nicolas; Morin, Soizic; Moreira, Sylvia; Delest, Brigitte; Budzinski, Hélène

2015-03-01

391

Analysis of insecticidal proteins from Bacillus thuringiensis and recombinant Escherichia coli by capillary electrokinetic chromatography.  

PubMed

Bacillus thuringiensis and recombinant Escherichia coli proteinaceous protoxins were subject to proteolysis and analyzed by capillary electrokinetic chromatography. Three resulting toxins (65 kDa) were baseline-resolved within 22 min using a 10 mM borate, pH 11 separation buffer consisting of 25 mM sodium dodecyl sulfate (SDS) and 30 mM phytic acid. The toxins displayed differential interactions with the SDS and phytic acid phases to effect their separation. The ion-pairing interaction between the analyte and phytic acid was also useful in preventing adsorption to the capillary walls and thus enhanced separation resolution and efficiency. The use of electrokinetic chromatography allows achievement of the separation in a significantly shorter time than conventional high-performance liquid chromatography (HPLC) using a diethylaminoethyl (DEAE) weak-anion exchanger. PMID:15472953

Luong, John H T; Male, Keith B; Mazza, Alberto; Masson, Luke; Brousseau, Roland

2004-10-01

392

Complementary fragmentation pattern analysis by gas chromatography–mass spectrometry and liquid chromatography tandem mass spectrometry confirmed the precious lignan content of Cirsium weeds  

Microsoft Academic Search

In this paper, as novelties to the field, it is confirmed at first, that the fruits of Cirsium species, regarded as injurious weeds, do contain lignans, two, different butyrolactone-type glycoside\\/aglycone pairs: the well known arctiin\\/arctigenin and the particularly rare tracheloside\\/trachelogenin species. These experiences were supported by gas chromatography–mass spectrometry (GC–MS), by liquid chromatography tandem mass spectrometry (LC–MS\\/(MS)) and by nuclear

I. Boldizsár; M. Kraszni; F. Tóth; B. Noszál; I. Molnár-Perl

2010-01-01

393

Analysis of hydroxy fatty acids as pentafluorobenzyl ester, trimethylsilyl ether derivatives by electron ionization gas chromatography\\/mass spectrometry  

Microsoft Academic Search

Electron ionization (EI) gas chromatography\\/mass spectrometry (GC\\/MS) analysis of pentafluorobenzyl ester-trimethyl sllyl\\u000a ether (PFB-TMS) derivatives of hydroxy-subshtuted fatty acids provides structural information comparable to that obtained\\u000a in analysis of methyl ester-trimethyl silyl ether (Me-TMS) derivatives. Use of this derivative eliminates the need to prepare\\u000a two separate derivatives, the PFB-TMS derivative for molecular weight determination by electron capture ionization (negative\\u000a ions)

Pat Wheelan; Joseph A. Zirrolli; Robert C. Murphy

1995-01-01

394

Rapid, quantitative analysis of americium, curium and plutonium isotopes in Hanford samples using extraction chromatography and precipitation plating  

SciTech Connect

Recently developed methods for the rapid, quantitative analysis of americium (Am), curium (Cm), and plutonium (Pu) isotopes in Hanford soil, sludge, and waste-tank samples are described. After dissolution, dilutions are made as necessary based on alpha-energy analysis of a small aliquot of the original solution. isotopic tracers are then added and Am-Cm and Pu are separated by extraction chromatography, coprecipitated with neodymium fluoride, and counted. Examples of alpha spectra are given, and results obtained for Hanford sludge samples are presented.

Kaye, J.H.; Strebin, R.S. [Pacific Northwest Lab., Richland, WA (United States); Orr, R.D. [Northern State Univ., Aberdeen, SD (United States)

1994-04-01

395

Neuere Chromatographie  

NASA Astrophysics Data System (ADS)

Besides high-performance liquid chromatography (HPLC) which is now a well-established and currently used technique, several emerging methods for the isolation and separation of natural products are receiving considerable attention. Centrifugal thin-layer chromatography is a very rapid technique, but limited in resolution. Of special interest are the recently developed support-free liquid-liquid chromatography methods such as droplet counter-current chromatography (DCCC) and rotation locular counter-current chromatography (RLCC). This latter method was applied to the separation of the enantiomers of (±)-norephedrine.

Hostettmann, K.

1983-04-01

396

Study on flow-pattern identification method using pressure drop characteristics of gas-liquid flow in narrow channel  

NASA Astrophysics Data System (ADS)

To clarify flow-pattern of gas-liquid two-phase flow in narrow channel is important because flow-pattern of gas-liquid two-phase flow relates closely to better working of industrial products like polymer electrolyte fuel cell (PEFC), µ-TAS, small size of fuel assembly, or cooling system of small electronic devices. Moreover, gas-liquid two-phase flow in narrow channel is different from that in usual size channel, including standard inch pipe, better knowledge of flow-pattern leads to more performance and operating safety in such products. However, flow-pattern has been mostly identified to observe visible image. Therefore, it is necessary to identified flow-pattern without making inside visible because of safety or cost performance. As the identification of flow-pattern method, it uses us pressure drop fluctuations in narrow channel.

Konishi, Tatsunori; Yoshida, Kenji; Kataoka, Isao

2012-03-01

397

Preparative isolation and analysis of alcohol dehydrogenase inhibitors from Glycyrrhiza uralensis root using ultrafiltration combined with high-performance liquid chromatography and high-speed countercurrent chromatography.  

PubMed

A simple, rapid, and effective assay based on ultrafiltration combined with high-performance liquid chromatography and high-speed countercurrent chromatography was developed for screening and purifying alcohol dehydrogenase inhibitors from Glycyrrhiza uralensis root extract. Experiments were carried out to optimize binding conditions including alcohol dehydrogenase concentration, incubation time, temperature, and pH. By comparing the chromatograms, three compounds were found possessing alcohol dehydrogenase binding activity in Glycyrrhiza uralensis root. Under the target-guidance of ultrafiltration combined with the high-performance liquid chromatography experiment, liquiritin (1), isoliquiritin (2), and liquiritigenin (3) were separated by high-speed countercurrent chromatography using ethyl acetate/methanol/water (5:1:4) as the solvent system. The alcohol dehydrogenase inhibitory activities of these three isolated compounds were assessed; compound 2 showed strongest inhibitory activity with an IC50 of 8.95 ?M. The results of the present study indicated that the combinative method using ultrafiltration, high-performance liquid chromatography and high-speed countercurrent chromatography could be widely applied for the rapid screening and isolation of enzyme inhibitors from complex mixtures. PMID:24723388

Chen, Miao; Liu, Liangliang; Chen, Xiaoqing

2014-07-01

398

Analysis of aliphatic biopolymers using thermochemolysis with tetramethylammonium hydroxide (TMAH) and gas chromatography- mass spectrometry  

Microsoft Academic Search

Abstract—Selected aliphatic biopolyesters (cutins, cuticles and a suberin) isolated from diÄerent plants have,been,analyzed,using thermochemolysis,with,tetramethylammonium,hydroxide,(TMAH). This method consists of a high-temperature saponification\\/transesterification, and yields methyl esters of fatty acids and the methyl ethers of alcohols, which are subsequently analyzed by gas chromatography and,gas chromatography?mass spectrometry. The main,compounds,produced,from,the analyzed samples correspond to the methyl derivatives of long-chain fatty acids, hydroxy fatty acids

PATRICK G. HATCHER

1998-01-01

399

Residue analysis of glucocorticoids in bovine milk by liquid chromatography–tandem mass spectrometry  

Microsoft Academic Search

A sensitive liquid chromatography–tandem mass spectrometry (LC-MS\\/MS) method for the simultaneous determination of 13 steroidal\\u000a anti-inflammatory drugs in bovine milk is presented. Due to their weakly acid nature, analytes were separated by ion suppression\\u000a reversed phase chromatography and detected in positive-ion mode by a high flow electrospray source. Dexamethasone-d4 was used\\u000a as internal standard. The sample preparation was simple and

Fulvia Caretti; Alessandra Gentili; Annalisa Ambrosi; Lucia Mainero Rocca; Maurizio Delfini; Maria Enrica Di Cocco; Giuseppe D’Ascenzo

2010-01-01

400

Derivatization and fragmentation pattern analysis of natural and synthetic steroids, as their trimethylsilyl (oxime) ether derivatives by gas chromatography mass spectrometry: Analysis of dissolved steroids in wastewater samples  

Microsoft Academic Search

This paper reports the extension of our multiresidue analysis (MA) procedure with 18 natural and synthetic steroids; permitting the identification and quantification, in total of 81 pollutants from one solution, by a single injection, as their trimethylsilyl (TMS)-oxime ether\\/ester derivatives, by gas chromatography–mass spectrometry (GC–MS), within 31min. As a novelty to the field, basic researches, such as fragmentation pattern analysis

N. Andrási; A. Helenkár; Gy. Záray; A. Vasanits; I. Molnár-Perl

2011-01-01

401

Advancement and application of gas chromatography isotope ratio mass spectrometry techniques for atmospheric trace gas analysis  

NASA Astrophysics Data System (ADS)

The use of gas chromatography isotope ratio mass spectrometry (GC-IRMS) for compound specific stable isotope analysis is an underutilized technique because of the complexity of the instrumentation and high analytical costs. However stable isotopic data, when coupled with concentration measurements, can provide additional information on a compounds production, transformation, loss, and cycling within the biosphere and atmosphere. A GC-IRMS system was developed to accurately and precisely measure delta13C values for numerous oxygenated volatile organic compounds having natural and anthropogenic sources. The OVOCs include methanol, ethanol, acetone, methyl ethyl ketone, 2-pentanone, and 3-pentanone. Guided by the requirements for analysis of trace components in air, the GC-IRMS system was developed with the goals of increasing sensitivity, reducing dead-volume and peak band broadening, optimizing combustion and water removal, and decreasing the split ratio to the IRMS. The technique relied on a two-stage preconcentration system, a low-volume capillary reactor and water trap, and a balanced reference gas delivery system. Measurements were performed on samples collected from two distinct sources (i.e. biogenic and vehicle emissions) and ambient air collected from downtown Miami and Everglades National Park. However, the instrumentation and the method have the capability to analyze a variety of source and ambient samples. The measured isotopic signatures that were obtained from source and ambient samples provide a new isotopic constraint for atmospheric chemists and can serve as a new way to evaluate their models and budgets for many OVOCs. In almost all cases, OVOCs emitted from fuel combustion were enriched in 13C when compared to the natural emissions of plants. This was particularly true for ethanol gas emitted in vehicle exhaust, which was observed to have a uniquely enriched isotopic signature that was attributed to ethanol's corn origin and use as an alternative fuel or fuel additive. Results from this effort show that ethanol's unique isotopic signature can be incorporated into air chemistry models for fingerprinting and source apportionment purposes and can be used as a stable isotopic tracer for biofuel inputs to the atmosphere on local to regional scales.

Giebel, Brian M.

2011-12-01

402

Parallelization of Catalytic Packed-Bed Microchannels with Pressure-Drop Microstructures for Gas-Liquid Multiphase Reactions  

NASA Astrophysics Data System (ADS)

High-throughput and stable treatments are required to achieve the practical production of chemicals with microreactors. However, the flow maldistribution to the paralleled microchannels has been a critical problem in achieving the productive use of multichannel microreactors for multiphase flow conditions. In this study, we newly designed and fabricated a glass four-channel catalytic packed-bed microreactor for the scale-up of gas-liquid multiphase chemical reactions. We embedded microstructures generating high pressure losses at the upstream side of each packed bed, and experimentally confirmed the efficacy of the microstructures in decreasing the maldistribution of the gas-liquid flow to the parallel microchannels.

Murakami, Sunao; Ohtaki, Kenichiro; Matsumoto, Sohei; Inoue, Tomoya

2012-06-01

403

Generating gas\\/liquid\\/liquid three-phase microdispersed systems in double T-junctions microfluidic device  

Microsoft Academic Search

This article describes the generation of microdispersed bubbles and droplets in a double T-junctions microfluidic device to\\u000a form immiscible gas\\/liquid\\/liquid three-phase flowing systems. Segmented gas plugs are controllably prepared in water at the\\u000a first T-junction to form gas\\/liquid two-phase fluid with the perpendicular flow cutting method. Then using this two-phase\\u000a fluid as the cross-shearing fluid for the oil phase at

K. Wang; Y. C. Lu; J. Tan; B. D. Yang; G. S. Luo

2010-01-01

404

Analysis of biodiesel conversion using thin layer chromatography and nonlinear calibration curves  

Microsoft Academic Search

Biodiesel (BD) is a fuel produced by the (trans)esterification reaction between the components of vegetable oil (or animal fat) and an alcohol. The presence of several substrates complicates analytical separation of the mixture, yet understanding of the complex reaction kinetics requires acquisition of a large body of data. The two well-established methods of gas chromatography (GC) and HPLC are time

Sergey N. Fedosov; Jesper Brask; Xuebing Xu

2011-01-01

405

(PRESENT AT NCCU) ANALYSIS OF SELECTED PYRETHROID PESTICIDES USING REVERSE PHASE HIGH LIQUID CHROMATOGRAPHY  

EPA Science Inventory

This research was conducted in cooperation with EPA Region 4 in Athens, GA to develop a method to analyze selected pyrethroid pesticides using Reverse Phase-High Pressure Liquid Chromatography (HPLC). This HPLC method will aid researchers in separating and identifying these pyre...

406

Analysis of Currently Available Analgesic Tablets by Modern Liquid Chromatography: An Undergraduate Laboratory Introduction to HPLC.  

ERIC Educational Resources Information Center

Background information, procedures, and results, are provided for an undergraduate experiment in which analgesic tablets are analyzed using liquid chromatography. The experiment, an improved, modified version of the Waters Associates Inc. experiment, is simple to prepare, requiring little glassware and minimal sample manipulation by students. (JN)

Kagel, R. A.; Farwell, S. O.

1983-01-01

407

Chemiluminescence detection in liquid chromatography: Applications to clinical, pharmaceutical, environmental and food analysis—A review  

Microsoft Academic Search

Chemiluminescence (CL)-based detection has become in the last years quite a useful detecting tool in liquid chromatography (HPLC) due to its simplicity, low cost and high sensitivity and selectivity, and the development in instrumentation. Minimal instrumentation is required and no external light source is needed; thus, the optical system is quite simple. As a consequence, a wide variety of analytical

Laura Gámiz-Gracia; Ana M. García-Campaña; José F. Huertas-Pérez; Francisco J. Lara

2009-01-01

408

ANALYSIS OF TRIGLYCERIDES AND RELATED COMPOUNDS IN FOOD USING LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY TECHNIQUES  

Technology Transfer Automated Retrieval System (TEKTRAN)

The most common ionization sources available today to couple liquid chromatography (LC) with mass spectrometry (MS) are atmospheric pressure ionization (API) sources that form ions at ambient pressure and sample them into the high vacuum region of the mass analyzer. The two most popular API sources...

409

SURVEY ANALYSIS OF PHENOLIC COMPOUNDS IN INDUSTRIAL EFFLUENTS BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY  

EPA Science Inventory

Analyzing industrial effluents for phenolic compounds involves a number of problems both in the separation of these compounds from the aqueous medium and in the chromatography of the extracted compounds. Use of continuous liquid-liquid extractor improved the recovery of phenolic ...

410

Selective and quantitative analysis of 4-hydroxybenzoate preservatives by microemulsion electrokinetic chromatography  

Microsoft Academic Search

A microemulsion electrokinetic chromatography (MEEKC) method has been developed and validated for the determination of 4-hydroxybenzoates and their impurities. These materials are commonly known as parabens and are widely used as preservatives in foods, cosmetics and pharmaceuticals. The method was shown to be selective and quantitative for the methyl, ethyl, propyl and butyl esters of 4-hydroxybenzoic acid. An internal standard,

P.-E. Mahuzier; K. D. Altria; B. J. Clark

2001-01-01

411

Analysis of Peppermint Leaf and Spearmint Leaf Extracts by Thin-Layer Chromatography  

ERIC Educational Resources Information Center

In this inquiry-based activity, the usefulness of thin-layer chromatography (TLC) to visualize the difference between spearmint and peppermint is explored. The experiment may be used in any class where TLC is discussed from high school to college. We have used this activity with science majors in an organic chemistry laboratory, with non-science…

Pelter, Libbie S. W.; Amico, Andrea; Gordon, Natalie; Martin, Chylah; Sandifer, Dessalyn; Pelter, Michael W.

2008-01-01

412

APPLICATION OF GC/ITD (GAS CHROMATOGRAPHY/ION TRAP DETECTOR) TO ENVIRONMENTAL ANALYSIS (JOURNAL VERSION)  

EPA Science Inventory

The choice of gas chromatography (GC) detectors has expanded rapidly. The necessity for mass spectrometric (MS) characterization of GC effluents stems from the complexity of the matrices associated with environmental samples. There are currently several MS types being used in con...

413

Gas Chromatography  

NSDL National Science Digital Library

This video, distributed on YouTube by the Royal Society of Chemistry, is on the basic principles of Gas Chromatography. This video is a short primer which introduces the technique and instrumentation. There are many assumptions that are made in the presentation of this material, due to the fact the video is meant to be a basic introduction. The ultimate strength of this video is the general nature of the content that makes it appealing to a wide audience. The video may be most appropriate in a lower-level general education science course (i.e forensic science) or as a quick orientation video for instrumental analysis students. The GC-FID and GC-MS are highlighted. Running time for the video is 5:17.

414

Current trends in green liquid chromatography for the analysis of pharmaceutically active compounds in the environmental water compartments.  

PubMed

Green analytical chemistry is an aspect of green chemistry which introduced in the late nineties. The main objectives of green analytical chemistry are to obtain new analytical technologies or to modify an old method to incorporate procedures that use less hazardous chemicals. There are several approaches to achieve this goal such as using environmentally benign solvents and reagents, reducing the chromatographic separation times and miniaturization of analytical devices. Traditional methods used for the analysis of pharmaceutically active compounds require large volumes of organic solvents and generate large amounts of waste. Most of them are volatile and harmful to the environment. With the awareness about the environment, the development of green technologies has been receiving increasing attention aiming at eliminating or reducing the amount of organic solvents consumed everyday worldwide without loss in chromatographic performance. This review provides the state of the art of green analytical methodologies for environmental analysis of pharmaceutically active compounds in the aquatic environment with special emphasis on strategies for greening liquid chromatography (LC). The current trends of fast LC applied to environmental analysis, including elevated mobile phase temperature, as well as different column technologies such as monolithic columns, fully porous sub-2 ?m and superficially porous particles are presented. In addition, green aspects of gas chromatography (GC) and supercritical fluid chromatography (SFC) will be discussed. We pay special attention to new green approaches such as automation, miniaturization, direct analysis and the possibility of locating the chromatograph on-line or at-line as a step forward in reducing the environmental impact of chromatographic analyses. PMID:25476373

Shaaban, Heba; Górecki, Tadeusz

2015-01-01

415

Analysis of chemical profiles of insect adhesion secretions by gas chromatography-mass spectrometry.  

PubMed

This article reports on the chemical analysis of molecular profiles of tarsal secretions of the desert locust Schistocerca gregaria (Forsskål, 1775) by gas chromatography hyphenated with quadrupol mass spectrometry (GC-MS) as well as (1)H-nuclear magnetic resonance ((1)H NMR) spectroscopy. Special focus of this study was to elaborate on sampling methods which enable selective microscale extraction of insect secretions in a spatially controlled manner, in particular tarsal adhesive secretions and secretions located on cuticle surfaces at the tibia. Various solvent sampling procedures and contact solid-phase microextraction (SPME) methods were compared in terms of comprehensiveness and extraction efficiencies as measured by signal intensities in GC-MS. Solvent sampling with water as extraction solvent gave access to the elucidation of chemical profiles of polar compound classes such as amino acids and carbohydrates, but is extremely tedious. Contact SPME on the other hand can be regarded as a simplified and more elegant alternative, in particular for the lipophilic compound fraction. Many proteinogenic amino acids and ornithine as well as carbohydrate monomers arabinose, xylose, glucose, and galactose were detected in tarsal secretions after acid hydrolysis of aqueous extracts. Qualitatively similar but quantitatively significantly different molecular profiles were found for the lipid fraction which contained mainly n-alkanes and internally branched monomethyl-, dimethyl-, and trimethyl-alkanes in the C23-C49 range as well as long chain fatty acids and aldehydes. Especially, hydrocarbons with >C40 carbon numbers have previously been rarely reported for insect secretions. The results suggest that the investigated insect secretions are complex emulsions which allow the attachment of tarsi on various otherwise incompatible materials of smooth and rough surfaces. The solid consistence of the established alkanes at ambient temperatures might contribute to a semi-solid consistence of the adhesive, amalgamating partly opposing functions such as slip resistance, tarsal release, desiccation resistance, and mechanical compliance. The methods developed can be extended to other similar applications of studying compositions of insect secretions of other species. PMID:25479867

Reitz, Manuela; Gerhardt, Heike; Schmitt, Christian; Betz, Oliver; Albert, Klaus; Lämmerhofer, Michael

2015-01-01

416

Aggregation analysis of pharmaceutical human immunoglobulin preparations using size-exclusion chromatography and analytical ultracentrifugation sedimentation velocity.  

PubMed

In the pharmaceutical industry, analysis of soluble aggregates in pharmaceutical formulations is most commonly performed using size-exclusion chromatography (SEC). However, owing to concerns that aggregates can be overlooked by SEC analysis, it has been suggested that its results should be confirmed with orthogonal methods. One of the main alternative methods for SEC is analytical ultracentrifugation sedimentation velocity (AUC-SV), which has been indicated as an important tool for the measurement of protein aggregation. The present study aimed to show that AUC-SV can be effectively applied for the characterization of marketed immunoglobulin pharmaceutical preparations to support the results obtained by SEC. In addition, the present research aimed to assess the appropriateness of two integration approaches for the quantitative analysis of the SEC results. Thus, the aggregates were measured in seven different preparations of human immunoglobulins by AUC-SV and SEC, and the acquired chromatographic data were processed by using either the vertical drop method or the Gaussian skim approach, implemented in the Empower II chromatography data software (Waters, Tokyo, Japan). The results of aggregation measurements performed using AUC-SV were in good agreement with those obtained using SEC. As expected, the Gaussian skim integration approach inherently provided lower estimates of aggregation content than the results of the vertical drop method. The finding of this study confirmed the complementary nature of AUC-SV to SEC for aggregate composition analysis and underscored the important role that the different integration methods can play in the quantitative interpretation of chromatographic results. PMID:22925901

Krayukhina, Elena; Uchiyama, Susumu; Nojima, Kiyoko; Okada, Yoshiaki; Hamaguchi, Isao; Fukui, Kiichi

2013-01-01

417

Computer code for gas-liquid two-phase vortex motions: GLVM  

NASA Technical Reports Server (NTRS)

A computer program aimed at the phase separation between gas and liquid at zero gravity, induced by vortex motion, is developed. It utilizes an explicit solution method for a set of equations describing rotating gas-liquid flows. The vortex motion is established by a tangential fluid injection. A Lax-Wendroff two-step (McCormack's) numerical scheme is used. The program can be used to study the fluid dynamical behavior of the rotational two-phase fluids in a cylindrical tank. It provides a quick/easy sensitivity test on various parameters and thus provides the guidance for the design and use of actual physical systems for handling two-phase fluids.

Yeh, T. T.

1986-01-01

418

Control and ultrasonic actuation of a gas-liquid interface in a microfluidic chip  

E-print Network

This article describes the design and manufacturing of a microfluidic chip, allowing for the actuation of a gas-liquid interface and of the neighboring fluid. A first way to control the interface motion is to apply a pressure difference across it. In this case, the efficiency of three different micro-geometries at anchoring the interface is compared. Also, the critical pressures needed to move the interface are measured and compared to theoretical result. A second way to control the interface motion is by ultrasonic excitation. When the excitation is weak, the interface exhibits traveling waves, which follow a dispersion equation. At stronger ultrasonic levels, standing waves appear on the interface, with frequencies that are half integer multiple of the excitation frequency. An associated microstreaming flow field observed in the vicinity of the interface is characterized. The meniscus and associated streaming flow have the potential to transport particles and mix reagents.

Jie Xu; Daniel Attinger

2009-12-15

419

Yield of H2O2 in Gas-Liquid Phase with Pulsed DBD  

NASA Astrophysics Data System (ADS)

Electric discharge in water can generate a large number of oxidants such as ozone, hydrogen peroxide and hydroxyl radicals. In this paper, a non-thermal plasma processing system was established by means of pulsed dielectric barrier discharge in gas-liquid phase. The electrodes of discharge reactor were staggered. The yield of H2O2 was enhanced after discharge. The effects of discharge time, discharge voltage, frequency, initial pH value, and feed gas were investigated. The concentration of hydrogen peroxide and ozone was measured after discharge. The experimental results were fully analyzed. The chemical reaction equations in water were given as much as possible. At last, the water containing Rhodamine B was tested in this system. The degradation rate came to 94.22% in 30 min.

Jiang, Song; Wen, Yiyong; Liu, Kefu

2014-01-01

420

An effective device for gas-liquid oxygen removal in enclosed microalgae culture.  

PubMed

A high-performance gas-liquid transmission device (HPTD) was described in this paper. To investigate the HPTD mass transfer characteristics, the overall volumetric mass transfer coefficients, K(A)(La,CO(2)) for the absorption of gaseous CO(2) and K(A)(La,O(2)) for the desorption of dissolved O(2) were determined, respectively, by titration and dissolved oxygen electrode. The mass transfer capability of carbon dioxide was compared with that of dissolved oxygen in the device, and the operating conditions were optimized to suit for the large-scale enclosed micro-algae cultivation. Based on the effectiveness evaluation of the HPTD applied in one enclosed flat plate Spirulina culture system, it was confirmed that the HPTD can satisfy the demand of the enclosed system for carbon supplement and excessive oxygen removal. PMID:18779934

Su, Zhenfeng; Kang, Ruijuan; Shi, Shaoyuan; Cong, Wei; Cai, Zhaoling

2010-01-01

421

Unit operations for gas-liquid mass transfer in reduced gravity environments  

NASA Technical Reports Server (NTRS)

Basic scaling rules are derived for converting Earth-based designs of mass transfer equipment into designs for a reduced gravity environment. Three types of gas-liquid mass transfer operations are considered: bubble columns, spray towers, and packed columns. Application of the scaling rules reveals that the height of a bubble column in lunar- and Mars-based operations would be lower than terrestrial designs by factors of 0.64 and 0.79 respectively. The reduced gravity columns would have greater cross-sectional areas, however, by factors of 2.4 and 1.6 for lunar and Martian settings. Similar results were obtained for spray towers. In contract, packed column height was found to be nearly independent of gravity.

Pettit, Donald R.; Allen, David T.

1992-01-01

422

Precolumn sample-enrichment device for analysis of ambient volatile organics by gas chromatography-mass spectrometry  

SciTech Connect

Gas chromatographic-mass spectrometric (GC/MS) identification of air pollutants generally requires a preconcentration step to provide sufficient sample for analysis. Cryogenic trapping is often used to enrich the sample since nitrogen and oxygen are not condensed. It does, however, concentrate enormous quantities of water and carbon dioxide - enough to plug high-resolution narrow-bore capillary columns needed for separation of complex environmental samples. Whole-air samples were collected in stainless steel containers or Tedlar bags for analysis by gas chromatography with flame ionization detection (GC/FID). In order to provide identification of unknown peaks and confirmation of tentatively named peaks, the system described herein was designed and built to enrich samples for GC/MS analysis of volatile organics. The preconcentration system consists of a solid sorbent trap and a cryogenic trap used in sequence to collect organic vapors and focus them for analysis by GC/MS.

Arnts, R.R.

1985-01-01

423

Determinations of gas-liquid partition coefficients using capillary chromatographic columns. Alkanols in squalane.  

PubMed

This study focused on an investigation into the experimental quantities inherent in the determination of partition coefficients from gas-liquid chromatographic measurements through the use of capillary columns. We prepared several squalane - (2,6,10,15,19,23-hexamethyltetracosane) - containing columns with very precisely known phase ratios and determined solute retention and hold-up times at 30, 40, 50 and 60°C. We calculated infinite dilution partition coefficients from the slopes of the linear regression of retention factors as a function of the reciprocal of the phase ratio by means of fundamental chromatographic equations. In order to minimize gas-solid and liquid-solid interface contributions to retention, the surface of the capillary inner wall was pretreated to guarantee a uniform coat of stationary phase. The validity of the proposed approach was first tested by estimating the partition coefficients of n-alkanes between n-pentane and n-nonane, for which compounds data from the literature were available. Then partition coefficients of sixteen aliphatic alcohols in squalane were determined at those four temperatures. We deliberately chose these highly challenging systems: alcohols in the reference paraffinic stationary phase. These solutes exhibited adsorption in the gas-liquid interface that contributed to retention. The corresponding adsorption constant values were estimated. We fully discuss here the uncertainties associated with each experimental measurement and how these fundamental determinations can be performed precisely by circumventing the main drawbacks. The proposed strategy is reliable and much simpler than the classical chromatographic method employing packed columns. PMID:23659974

Tascon, Marcos; Romero, Lílian M; Acquaviva, Agustín; Keunchkarian, Sonia; Castells, Cecilia

2013-06-14

424

The inactivation of Chlorella spp. with dielectric barrier discharge in gas-liquid mixture  

NASA Astrophysics Data System (ADS)

The inactivation of Chlorella spp. with high voltage and frequency pulsed dielectric barrier discharge in hybrid gas-liquid reactor with a suspension electrode was studied experimentally. In the hybrid gas-liquid reactor, a steel plate was used as high voltage electrode while a quartz plate as a dielectric layer, another steel plate placing in the aqueous solution worked as a whole ground electrode. A suspension electrode is installed near the surface of solution between high voltage and ground electrode to make the dielectric barrier discharge uniform and stable, the discharge gap was between the quartz plate and the surface of the water. The effect of peak voltage, treatment time, the initial concentration of Chlorella spp. and conductivity of solution on the inactivation rate of Chlorella spp. was investigated, and the inactivation mechanism of Chlorella spp. preliminarily was studied. Utilizing this system inactivation of Chlorella spp., the inactivation rate increased with increasing of peak voltage, treatment time and electric conductivity. It was found that the inactivation rate of Chlorella spp. arrived at 100% when the initial concentration was 4 × 106 cells mL-1, and the optimum operation condition required a peak voltage of 20 kV, a treatment time of 10 min and a frequency of 7 kHz. Though the increasing of initial concentration of the Chlorella spp. contributed to the addition of interaction probability between the Chlorella spp. and O3, H2O2, high-energy electrons, UV radiation and other active substances, the total inactivation number raise, but the inactivation rate of the Chlorella spp. decreased.

Song, Dan; Sun, Bing; Zhu, Xiaomei; Yan, Zhiyu; Liu, Hui; Liu, Yongjun

2013-03-01

425

DESIGN AND DEVELOPMENT OF GAS-LIQUID CYLINDRICAL CYCLONE COMPACT SEPARATORS FOR THREE-PHASE FLOW  

SciTech Connect

The U.S. Department of Energy (DOE) has awarded a five-year (1997-2002) grant (Mohan and Shoham, DE-FG26-97BC15024, 1997) to The University of Tulsa, to develop compact multiphase separation components for 3-phase flow. The research activities of this project have been conducted through cost sharing by the member companies of the Tulsa University Separation Technology Projects (TUSTP) research consortium and the Oklahoma Center for the Advancement of Science and Technology (OCAST). As part of this project, several individual compact separation components have been developed for onshore and offshore applications. These include gas-liquid cylindrical cyclones (GLCC{copyright}), liquid-liquid cylindrical cyclones (LLCC{copyright}), and the gas-liquid-liquid cylindrical cyclones (GLLCC{copyright}). A detailed study has also been completed for the liquid-liquid hydrocyclones (LLHC). Appropriate control strategies have been developed for proper operation of the GLCC{copyright} and LLCC{copyright}. Testing of GLCC{copyright} at high pressure and real crude conditions for field applications is also completed. Limited studies have been conducted on flow conditioning devices to be used upstream of the compact separators for performance improvement. This report presents a brief overview of the activities and tasks accomplished during the 5-year project period, October 1, 1997-March 31, 2003 (including the no-cost extended period of 6 months). An executive summary is presented initially followed by the tasks of the 5-year budget periods. Then, detailed description of the experimental and modeling investigations are presented. Subsequently, the technical and scientific results of the activities of this project period are presented with some discussions. The findings of this investigation are summarized in the ''Conclusions'' section, followed by relevant references. The publications resulting from this study in the form of MS Theses, Ph.D. Dissertation, Journal Papers and Conference Presentations are provided at the end of this report.

Dr. Ram S. Mohan; Dr. Ovadia Shoham

2003-06-25

426

A novel method for measuring hollow fiber membrane permeability in a gas-liquid system.  

PubMed

Designing an effective intravenous membrane oxygenator requires selecting hollow fiber membranes (HFMs) that present minimal resistance to gas exchange over extended periods of time. Microporous fiber membranes, as used in extracorporeal oxygenators, offer a minimal exchange resistance, but one that diminishes with time because of fiber wetting and subsequent serum leakage. Potentially attractive alternatives are composite HFMs, which inhibit fiber wetting and serum leakage by incorporating a true membrane layer within their porous walls. To evaluate composite and other HFMs, the authors developed a simple apparatus and method for measuring HFM permeability in a gas-liquid system under conditions relevant to intravenous oxygenation. The system requires only a small volume of liquid that is mixed with a pitched blade impeller driven by a direct current motor at controlled rates. Mass flux is measured from the gas flow exiting the fibers, eliminating the necessity of measuring any liquid side conditions. The authors measured the CO2 exchange permeabilities of Mitsubishi MHF 200L composite HFMs, KPF 280E microporous HFMs, and KPF 190 microporous HFMs. The membrane permeabilities to CO2 were 9.3 x 10(-5) ml/cm2/sec/cmHg for the MHF 200L fiber, 4.7 x 10(-4) ml/cm2/sec/cmHg for the KPF 280E fiber, and 2.8 x 10(-4) ml/cm2/sec/cmHg for the KPF 190 fiber. From these results it is concluded that 1) because of liquid-fiber surface interactions, the permeabilities of the microporous fibers are several orders of magnitude less than would be measured for completely gas filled pores, emphasizing the importance of measuring microporous fiber permeability in a gas-liquid system; and 2) the liquid diffusional boundary layer adjacent to the fibers generated by the pitched blade impeller is unique to each fiber, resulting in different boundary layer characterizations. PMID:8944921

Lund, L W; Federspiel, W J; Walters, F R; Hattler, B G

1996-01-01

427

Foam formation and mitigation in a three-phase gas-liquid-particulate system.  

PubMed

Foaming is of great concern in a number of industrial processes involving three-phase gas-liquid-finely divided solid systems such as those encountered in the vitrification of highly radioactive nuclear waste slurries and sludges. Recent work has clearly shown that the surface properties of the particles such as hydrophilicity, hydrophobicity or biphilicity (i.e. partially wetted by water) are the cause of foamability and foam stability. The literature data on particles causing foaminess and foam stability in the absence of any surfactant are rather scarce. This paper presents experimental observations on aqueous foams with polyhedral structures containing over 90% air generated due to the presence of irregularly-shaped fine crystalline particles of sodium chloride which were modified into amphiphilic particles by physical adsorption of a cationic surfactant. Cross-polarized light microscopy was used to visualize the physical adsorption of the surfactant on the crystal surface. It is shown that these biphilic or amphiphilic particles attach to the air bubble surface and prevent the coalescence of bubbles, thereby extending the life of the foam. The foaming power of solid particles increases with an increase in the concentration of amphiphilic particles, and a maximum in foaminess is observed which is due to two competing effects. Amphiphilic particles promote foamability by attachment to the bubble surfaces as individual particles and foam inhibition due to the clustering or flocculation of particles in the bulk at high particle concentrations. We studied the adsorption of amphiphilic particles at a planar air-water surface and found that the degree of foamability correlates well with the particle coverage (i.e. adsorption density) at the air-liquid surface. An exploratory study was also conducted using an antifoam recently developed by IIT researchers to mitigate foaming in particle-laden gas-liquid systems. PMID:16997269

Vijayaraghavan, Krishna; Nikolov, Alex; Wasan, Darsh

2006-11-16

428

Solidphase micro-extraction–gas chromatography–(tandem) mass spectrometry as a tool for pesticide residue analysis in water samples at high sensitivity and selectivity with confirmation capabilities  

Microsoft Academic Search

Gas chromatography–mass spectrometry (GC–MS) has been widely applied for pesticide monitoring because of its high sensitivity and specificity and for the potential of multi-residue and multi-class analysis. An analytical procedure was developed for the determination of pesticide multi-residues in water samples combining solid-phase micro-extraction (SPME) and gas chromatography–ion trap mass spectrometry. For SPME extraction a poly(dimethylsiloxane)–divinylbenzene coated fibre was selected

C Gonçalves; M. F Alpendurada

2004-01-01

429

Comprehensive two-dimensional liquid chromatography with evaporative light-scattering detection for the analysis of triacylglycerols in Borago officinalis.  

PubMed

An optimized 2-D liquid chromatography (LC×LC) set-up, based on the different selectivities of a silver ion (Ag) and a non-aqueous reversed phase (NARP), employed in the first (D1) and the second dimension (D2), respectively, in combination with evaporative light-scattering detection (ELSD), has been developed for the analysis of the triacylglycerol (TAG) fraction in a Borago officinalis oil. The 2-D set-up, thanks to the complementary separation selectivity provided by the two columns, allowed to distribute 78 TAGs throughout the 2-D LC retention plane otherwise unachievable by 1-D LC. PMID:21413146

Mondello, Luigi; Beccaria, Marco; Donato, Paola; Cacciola, Francesco; Dugo, Giovanni; Dugo, Paola

2011-03-01

430

Analysis of L-serine-O-phosphate in cerebrospinal spinal fluid by derivatization-liquid chromatography/mass spectrometry.  

PubMed

L-serine-O-phosphate (L-SOP), the precursor of L-serine, is a potent agonist against the group III metabotropic glutamate receptors (mGluRs) and, thus, is of interest as a potential biomarker for monitoring modulation of neurotransmitter release. So far, no reports are available on the analysis of L-SOP in cerebrospinal fluid (CSF). Here a novel method is presented to determine L-SOP levels in CSF employing precolumn derivatization with (5-N-succinimidoxy-5-oxopentyl)triphenylphosphonium bromide (SPTPP) coupled to liquid chromatography/mass spectrometry (derivatization-LC/MS, d-LC/MS). PMID:24534252

McNaney, Colleen A; Benitex, Yulia; Luchetti, David; Labasi, Jeffrey M; Olah, Timothy V; Morgan, Daniel G; Drexler, Dieter M

2014-05-01

431

Thin-layer chromatography and colorimetric analysis of multi-component explosive mixtures  

DOEpatents

A thin-layer chromatography method for detection and identification of common military and peroxide explosives in samples includes the steps of provide a reverse-phase thin-layer chromatography plate; prepare the plate by marking spots on which to deposit the samples by touching the plate with a marker; spot one micro liter of a first standard onto one of the spots, spot one micro liter of a second standard onto another of the spots, and spot samples onto other of spots producing a spotted plate; add eluent to a developing chamber; add the spotted plate to the developing chamber; remove the spotted plate from the developing chamber producing a developed plate; place the developed plate in an ultraviolet light box; add a visualization agent to a dip tank; dip the developed plate in the dip tank and remove the developed plate quickly; and detect explosives by viewing said developed plate.

Pagoria, Philip F.; Mitchell, Alexander R.; Whipple, Richard E.; Carman, M. Leslie

2014-08-26

432

Qualitative drug analysis of hair extracts by comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry.  

PubMed

A technique using comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GCxGC/TOFMS) is applied to a qualitative analysis of three sample extracts from hair suspected of containing various drug compounds. The samples were also subjected to a quantitative target analysis for codeine, morphine, 6-monoacetylmorphine (6-MAM), amphetamine, methamphetamine, methylenedioxyamphetamine (MDA), methylenedioxymethylamphetamine (MDMA), methadone, and benzylpiperazine (BZP) by liquid chromatography-tandem mass spectrometry (LC-MS/MS). GCxGC/TOFMS provided a non-specific procedure that identified various drugs, metabolites, and impurities not included in the target analysis. They included cocaine, diazepam, and methaqualone (quaalude). Comprehensive GCxGC separation was achieved using twin-stage cryo-modulation to focus eluant from a DB-5 ms (5% phenyl) to a BPX50 (50% phenyl) GC column. The TOF mass spectrometer provided unit mass resolution in the mass range m/z 5-1000 and rapid spectral acquisition (< or = 500spectra/s). Clean mass spectra of the individual components were obtained using mass spectral deconvolution software. The 'unknown' components were identified by comparison with mass spectra stored in a library database. PMID:20471020

Guthery, Bill; Bassindale, Tom; Bassindale, Alan; Pillinger, Colin T; Morgan, Geraint H

2010-06-25

433

Trace mycotoxin analysis in complex biological and food matrices by liquid chromatography-atmospheric pressure ionisation mass spectrometry.  

PubMed

Mycotoxins are toxic secondary metabolites produced by filamentous fungi that are growing on agricultural commodities. Their frequent presence in food and their severe toxic, carcinogenic and estrogenic properties have been recognised as potential threat to human health. A reliable risk assessment of mycotoxin contamination for humans and animals relies basically on their unambiguous identification and accurate quantification in food and feedstuff. While most screening methods for mycotoxins are based on immunoassays, unambiguous analyte confirmation can be easily achieved with mass spectrometric methods, like gas chromatography/mass spectrometry (GC/MS) or liquid chromatography/mass spectrometry (LC/MS). Due to the introduction of atmospheric pressure ionisation (API) techniques in the late 80s, LC/MS has become a routine technique also in food analysis, overcoming the traditional drawbacks of GC/MS regarding volatility and thermal stability. During the last few years, this technical and instrumental progress had also an increasing impact on the expanding field of mycotoxin analysis. The aim of the present review is to give an overview on the application of LC-(API)MS in the analysis of frequently occurring and highly toxic mycotoxins, such as trichothecenes, ochratoxins, zearalenone, fumonisins, aflatoxins, enniatins, moniliformin and several other mycotoxins. This includes also the investigation of some of their metabolites and degradation products. Suitable sample pre-treatment procedures, their applicability for high sample through-put and their influence on matrix effects will be discussed. The review covers literature published until July 2006. PMID:17087969

Zöllner, Peter; Mayer-Helm, Bernhard

2006-12-15

434

Simulated distillation of high-boiling petroleum fractions by capillary supercritical fluid chromatography and vacuum thermal gravimetric analysis  

SciTech Connect

Capillary supercritical fluid chromatography (SFC) and vacuum thermal gravimetric analysis (VTGA) were utilized for simulated distillation (SIMDIS) of high-boiling petroleum fractions obtained by short-path vacuum distillation. The SFC method covers the approximate boiling range of 250-1400/sup 0/F. Under the present conditions, even 42% of a nondistillable, nondeasphalted residue was recovered from the column at a calculated 1426/sup 0/F atmospheric equivalent boiling point. The influence of temperature and pressure on resolution and retention was studied. SFC-SIMDIS was performed by using linear pressure programming at 100/sup 0/C, as compared to 400/sup 0/C+ temperatures required for comparable samples when capillary gas chromatography (GC) is employed. Polysiloxane-coated, 50-..mu..m-i.d. columns permitted fast analyses (30-min run time) yet maintained adequate resolution for SIMDIS analysis. VTGA-SIMDIS data of samples in the 500-1000/sup 0/F boiling range yielded excellent correlation with actual distillation data. However, thermal analysis revealed decomposition of samples at temperatures exceeding ca. 370/sup 0/C. The validity of the SFC method was demonstrated by comparing SFC-SIMDIS data with those obtained by GC and VTGA.

Schwartz, H.E.; Brownlee, R.G.; Boduszynski, M.M.; Su, F.

1987-05-15

435

Comparison of different amino acid derivatives and analysis of rat brain microdialysates by liquid chromatography tandem mass spectrometry.  

PubMed

The efficiencies of three derivatisation reagents that react with either the amine (9-fluorenylmethyl chloroformate (FMOC)) or the carboxylic acid group (butanol) of amino acid or with both types of functional groups (propyl chloroformate) were compared in the analysis of amino acids by liquid chromatography-electrospray-tandem mass spectrometry (LC-ESI-MS/MS). Separation of 20 amino acids derivatised with these three reagents was studied on reversed-phase chromatography. Linearity, repeatability and limits of detection of the LC-ESI-MS/MS method were determined by analysing FMOC-, butanol- and propyl chloroformate-derivatised lysine, beta-aminobutyric acid, threonine and glutamic acid. The limits of detection for the derivatised amino acids (7.5-75fmol) were as much as 2-60 times lower than those of the corresponding underivatised molecules. The best linearity was observed for amino acids derivatised with propyl chloroformate or butanol (r(2)=0.996-0.999, range=100-8500nmolL(-1)). Propyl chloroformate was the best suited of the reagents tested for the analysis of amino acids with LC-MS/MS and was used for the analysis of amino acids in rat brain microdialysis samples. PMID:19166726

Uutela, Päivi; Ketola, Raimo A; Piepponen, Petteri; Kostiainen, Risto

2009-02-01

436

Accurate analysis of ginkgolides and their hydrolyzed metabolites by analytical supercritical fluid chromatography hybrid tandem mass spectrometry.  

PubMed

Hydrolysis plays an important role in the metabolic transformations of lactones. Analysis of lactones and their hydrolyzed metabolites in biological samples is challenging, because unexpected hydrolysis or reversed dehydration may occur depending on the test environments. In this work, a supercritical fluid chromatography hybrid triple-quadrupole mass spectrometry (SFC-QQQ MS) method has been proposed for simultaneous analysis of ginkgolides and hydrolyzed metabolites. The SFC utilizes carbon dioxide as the mobile phase, avoiding hydrolysis of ginkgolides that always happens during reversed phase liquid chromatographic detection. Compared with normal phase liquid chromatography, the SFC provides good resolutions especially for ginkgolide with similar structures. This SFC-QQQ MS method was validated in linearity, precision, accuracy, and stability for ginkgolides and metabolites. Then this method was successfully applied to pharmacokinetic study of 3 ginkgolides and their 6 hydrolyzed metabolites after intravenous administration of total ginkgolide extract. Ginkgolides and metabolites showed different clear rates and excluded in 2-4h. The developed SFC-QQQ MS method allows accurate determination of ginkgolides and metabolites with high resolutions, and can be extended to analysis of other water-unstable compounds. PMID:25728654

Liu, Xin-Guang; Qi, Lian-Wen; Fan, Zhi-Ying; Dong, Xin; Guo, Ru-Zhou; Lou, Feng-Chang; Fanali, Salvatore; Li, Ping; Yang, Hua

2015-04-01

437

The quantitative analysis of triglyceride mixtures by thin layer chromatography on silica impregnated with silver nitrate  

Microsoft Academic Search

The paper describes a procedure involving thin layer chromatography on silica impregnated with silver nitrate, which makes\\u000a possible the separation of synthetic and natural glyceride mixtures into classes according to their degree of unsaturation,\\u000a and within those classes the resolution of certain isomeric unsaturated glycerides. The separations depend upon the ability\\u000a of compounds having an olefinic double bond to form

C. B. Barrett; M. S. J. Dallas; F. B. Padley

1963-01-01

438

Analysis of lipids from cooked beef by thin-layer chromatography with flame-ionization detection  

Microsoft Academic Search

Lipids were extracted from cooked ground beef with methylene chloride\\/methanol (2:1). The lipids were separated on a silicic\\u000a acid column, into neutral and polar fractions by elution with methylene chloride, followed by methanol. These fractions were\\u000a analyzed by Iatroscan thin-layer chromatography with flame-ionization detection instrumentation on Chromarods S-III (silica\\u000a gelcoated quartz rods). Comparison of cooked beef stored for 0, 4

Allen J. St. Angelo; Charles James

1993-01-01

439

Signal analysis of NEMS sensors at the output of a chromatography column  

NASA Astrophysics Data System (ADS)

This article introduces a joined Bayesian estimation of gas samples issued from a gas chromatography column (GC) coupled with a NEMS sensor based on Giddings Eyring microscopic molecular stochastic model. The posterior distribution is sampled using a Monte Carlo Markov Chain and Gibbs sampling. Parameters are estimated using the posterior mean. This estimation scheme is finally applied on simulated and real datasets using this molecular stochastic forward model.

Bertholon, François; Harant, Olivier; Jutten, Christian; Bourlon, Bertrand; Gerfault, Laurent; Grangeat, Pierre

2015-01-01

440

Analysis of triterpenoids in Ganoderma lucidum using liquid chromatography coupled with electrospray ionization mass spectrometry  

Microsoft Academic Search

Triterpenoids extracted from Ganoderma lucidum (Leyss. ex Fr.) Karst were separated and characterized using optimized reversed-phase liquid chromatography with diode array\\u000a detection and electrospray ion trap tandem mass spectrometry (HPLC-DAD-ESI-MSn). They could be classified into five types depending on the fragmentation behavior. All triterpenoids gave [M?H]? and [2M?H]? ions by electrospray ionization monitored in the negative ion mode; in addition,

Min Yang; Xiaoming Wang; Shuhong Guan; Jiameng Xia; Jianghao Sun; Hui Guo; De-an Guo

2007-01-01

441

Analysis of autoxidized fats by gas chromatography-mass spectrometry: I. Methyl oleate  

Microsoft Academic Search

A structural investigation of autoxidation products of methyl oleate was carried out by gas chromatography-mass spectrometry\\u000a (GC-MS) of trimethylsilyl (TMS) ether derivatives. GC-MS using computer plots of selected masses afforded structural assignments\\u000a of GC peaks due to incompletely resolved mixtures. This method provided evidence of epoxy and keto esters which are not completely\\u000a separated from the main components consisting of

E. N. Frankel; W. E. Neff; W. K. Rohwedder; B. P. S. Khambay; R. F. Garwood; B. C. L. Weedon

1977-01-01

442

Analysis of autoxidized fats by gas chromatography-mass spectrometry: II. Methyl linoleate  

Microsoft Academic Search

The gas chromatography-mass spectrometry (GC-MS) approach developed in the preceding paper was applied for qualitative and\\u000a quantitative investigations of autoxidation products of methyl linoleate. A GC-MS computer summation method was standardized\\u000a with synthetic 9- and 13-hydroxyoctadecanoate. Equal amounts of 9- and 13-hydroperoxides were found in all samples of linoleate\\u000a autoxidized at different temperatures and peroxide levels. The results are consistent

E. N. Frankel; W. E. Neff; W. K. Rohwedder; B. P. S. Khambay; R. F. Garwood; B. C. L. Weedon

1977-01-01

443

Analysis of methylisothiazolones by ion pair high-performance liquid chromatography after pre-column derivatisation  

Microsoft Academic Search

Summary 2-Methyl-3(2H)-isothiazolone resp. 5-chloro-2-methyl-3(2H)-isothiazolone were isolated from a commercial methylisothiazolone formulation (Kathon CG) by flash chromatography and subsequently converted into the respectiveß-thio-substituted acrylamide derivative with the help of the nucleophilic reagent hydrogensulfite. UV spectra and absorption characteristics, for both the derivates as well as the original methylisothiazolones are given and represented in comparison. The derivatives differ clearly in their absorption

Reinhard Matissek; Regine Nagorka; Ingrid Wengatz; Jeannette Rohde

1988-01-01

444

High-performance liquid chromatography analysis of plant saponins: An update 2005-2010  

PubMed Central

Saponins are widely distributed in plant kingdom. In view of their wide range of biological activities and occurrence as complex mixtures, saponins have been purified and separated by high-performance liquid chromatography using reverse-phase columns at lower wavelength. Mostly, saponins are not detected by ultraviolet detector due to lack of chromophores. Electrospray ionization mass spectrometry, diode array detector , evaporative light scattering detection, and charged aerosols have been used for overcoming the detection problem of saponins. PMID:22303089

Negi, Jagmohan S.; Singh, Pramod; Pant, Geeta Joshi Nee; Rawat, M. S. M.

2011-01-01

445

Gas chromatography–mass spectrometry associated global analysis of rice root exudates under aseptical conditions  

Microsoft Academic Search

Components of rice root exudates were surveyed by gas chromatography–mass spectrometry (GC-MS) and the effect of phosphate (P) starvation was investigated. Rice seedlings were aseptically grown in controlled environments under P-supplied (+P) or P-deficient (–P) conditions. Root exudates were collected from the culture solution 4 and 8?days after treatment (D4 and D8, respectively), which contain the first and second 4-day

Katsumasa Suzuki; Keiki Okazaki; Keitaro Tawaraya; Mitsuru Osaki; Takuro Shinano

2009-01-01

446

Thin layer chromatography\\/flame ionization analysis of transesterified vegetable oils  

Microsoft Academic Search

A quantitative method was developed for analyzing mixtures containing fatty esters and tri- (TG), di- (DG) and monoglycerides\\u000a (MG) obtained by the transesterification of vegetable oils. Analyses were performed by thin layer chromatography (TLC)\\/flame\\u000a ionization detection (FID) with an Iatroscan TH-10 instrument. Stearyl alcohol served as an internal standard. From plots\\u000a of area and weight ratios of methyl linoleate and

B. Freedman; E. H. Pryde; W. F. Kwolek

1984-01-01

447

Analysis of Chlormequat residues in grain using liquid chromatography-mass spectrometry (LCMS\\/MS)  

Microsoft Academic Search

A fast, sensitive and specific method for routine determination of residues from Chlormequat (CAS no. 7003-89-6) is described.\\u000a The method is based on a simple clean-up using an SPE-C18 cartridge, high-performance liquid chromatography on a standard C18 column (Spherisorb S5 ODS1) and specific detection and quantification by electrospray mass spectrometry (LC-MS\\/MS). 13C-Chlormequat was synthesised for use as internal standard. Samples

Martin Vahl; Anette Graven; René K. Juhler

1998-01-01

448

Ultra performance liquid chromatography tandem mass spectrometry performance evaluation for analysis of antibiotics in natural waters  

Microsoft Academic Search

An ultra performance liquid chromatography electrospray tandem mass spectrometry (UPLC\\/MS\\/MS) method was developed and validated\\u000a for the determination of 17 antibiotics in natural waters in one single extraction and chromatographic procedure. Gradient\\u000a separation conditions were optimised for 17 compounds belonging to five different antibiotic groups: quinolones (oxolinic\\u000a acid, nalidixic acid, pipemidic acid, flumequine), fluoroquinolones (enoxacin, ciprofloxacin, norfloxacin, ofloxacin, enrofloxacin,\\u000a sarafloxacin,

Fatima Tamtam; Fabien Mercier; Joëlle Eurin; Marc Chevreuil; Barbara Le Bot

2009-01-01

449

Counter-current chromatography based analysis of synergy in an anti-tuberculosis ethnobotanical  

Microsoft Academic Search

The crude extract of an Alaskan ethnobotanical plant, Oplopanax horridus, was subjected to counter-current chromatography (CCC), and the selected active regions were evaluated for their synergistic effects with an in vitro model of anti-tubercular efficacy. CCC as a support-free high-resolution separation method was employed to preclude potential irreversible absorption to a solid stationary phase. The microplate Alamar blue assay and

Taichi Inui; Yuehong Wang; Shixin Deng; David C. Smith; Scott G. Franzblau; Guido F. Pauli

2007-01-01

450

Micellar electrokinetic chromatography for the analysis of d-amygdalin and its epimer in apricot kernel  

Microsoft Academic Search

We have developed a simple, rapid and reproducible method for the determination of d-amygdalin and its epimer by using micellar electrokinetic chromatography (MEKC). Separation of d-amygdalin was performed in a 20 mM sodium borate buffer (pH 8.5) containing 300 mM sodium dodecyl sulfate using a bare fused-silica capillary. The eluates were monitored by the absorbance at 210 nm. The applied

Seong Ho Kang; Hyunsook Jung; Namshin Kim; Dae-Ho Shin; Doo Soo Chung

2000-01-01

451

Analysis of oak tannins by liquid chromatography-electrospray ionisation mass spectrometry.  

PubMed

Extractable tannins were analysed by liquid chromatography-electrospray ionisation mass spectrometry in two oak species, North American white oak (Quercus alba) and European red oak (Quercus robur). They mainly included various glucose gallic and ellagic acid esters. The structures were partially determined, and they included grandinin/roburin E, castalagin/vescalagin, gallic acid, valoneic acid bilactone, monogalloyl glucose, digalloyl glucose, trigalloyl glucose, ellagic acid rhamnose, quercitrin and ellagic acid. PMID:10999626

Mämmelä, P; Savolainen, H; Lindroos, L; Kangas, J; Vartiainen, T

2000-09-01

452

Hair analysis for nordiazepam and oxazepam by gas chromatography-negative-ion chemical ionization mass spectrometry  

Microsoft Academic Search

A procedure is presented for the identification of nordiazepam and its metabolite, oxazepam, in human hair. The method involves decontamination of hair with dichloromethane, incubation in phosphate buffer (pH 7.6) in the presence of deuterated internal standards, liquid-liquid extraction, derivatization with N,O-bis(trimethylsilyl)trifluoroacetamide plus 1% trimethylchlorosilane and gas chromatography-mass spectrometry using negative-ion chemical ionization with methane. Among thirty samples obtained from

Pascal Kintz; Vincent Cirimele; François Vayssette; Patrice Mangin

1996-01-01

453

High-speed observation of the piston effect near the gas-liquid critical point Yuichi Miura,1  

E-print Network

High-speed observation of the piston effect near the gas-liquid critical point Yuichi Miura,1. In confined fluids, they are usually caused by a mechanical piston, but they can also be achieved by a heat at the boundary expands and plays the role of a thermal piston 1­11 . This method is efficient near the gas

454

Mass transfer and gas-liquid circulation in an airlift bioreactor with viscous non-Newtonian fluids  

Microsoft Academic Search

In an internal loop airlift reactor of 55 l working volume, gas-liquid volumetric oxygen mass transfer coefficient kLa, gas holdup ?G and liquid circulation time tc were measured with the solution of carboxymethyl cellulose to simulate the performance of a reactor with highly viscous broth. Electric conductivity and oxygen probes were used to measure the local gas holdup, liquid circulation

Guo-Qing Li; Shou-Zhi Yang; Zhao-Ling Cai; Jia-Yong Chen

1995-01-01

455

Gas-liquid two-phase flow across a bank of micropillars Santosh Krishnamurthy and Yoav Peles  

E-print Network

Gas-liquid two-phase flow across a bank of micropillars Santosh Krishnamurthy and Yoav Peles-water two-phase flow across a bank of staggered circular micropillars, 100 m long with a diameter of 100 m. Micropillars entrenched inside microchannels are of particular interest as they pro- vide increasing surface

Peles, Yoav

456

Fast Model Based Approximation of the Closed-loop Performance Limits of Gas/Liquid Inline Separators for Accelerated Design  

E-print Network

trend in the oil and gas (exploration & production) industry is to use compact ­centrifugal forces basedFast Model Based Approximation of the Closed-loop Performance Limits of Gas/Liquid Inline.fuenmayor@shell.com, ruud.henkes@shell.com) Abstract: A current trend in the oil and gas industry is to use compact so

Van den Hof, Paul

457

A Novel Process for Natural Gas Liquids Recovery from Oil Field Associated Gas with Liquefied Natural Gas Cryogenic Energy Utilization  

Microsoft Academic Search

A novel process to recovery natural gas liquids from oil field associated gas with liquefied natural gas (LNG) cryogenic energy utilization is proposed. Compared to the current electric refrigeration process, the proposed process uses the cryogenic energy of LNG and saves 62.6% of electricity. The proposed process recovers ethane, liquid petroleum gas (propane and butane) and heavier hydrocarbons, with total

Haijun BIAN; Wendong XU; Xiuxi LI; Yu QIAN

2011-01-01

458

Working process study of a novel scroll type multiphase pump for the transportation of gas-liquid mixtures  

NASA Astrophysics Data System (ADS)

A novel scroll type multiphase pump was proposed to transport gas-liquid two-phase mixture. There is a pressure unloading gap from compression chambers to the discharge port by constructing scroll wrap profile with variational meshing clearance in this scroll multiphase pump. In the working process when the volume of working chamber decreases, the pressure of gas-liquid mixtures increases gradually, at the same time small amounts of gas-liquid mixture are pushed to the discharge port from compression chambers through the pressure unloading gap. Therefore, this multiphase pump has an advantage of unloading pressure method automatically, and the frequently problem of liquid impacting in volume multiphase pump is solved. The safety and reliability of volumetric multiphase pump are improved, and the scope of multiphase pump of the gas-liquid ratio is expanded. The working process and the performance characteristics of scroll multiphase pump were analyzed too, and the generation method of scroll wrap profile with variational meshing clearance was investigated. The equations of the profile were obtained, and the changing principle of the working volume and the meshing clearance were analyzed. The geometric theory of scroll multiphase pump was formed. All of that lay the theoretical foundation for engineering design of this novel scroll.

Wang, J.; Zha, H. B.; Zhang, X. H.; Zhang, D. H.

2012-11-01

459

A FLOW-THROUGH METHOD FOR SCINTILLATION COUNTING OF CARBON14 AND TRITIUM IN GAS-LIQUID CHROMATOGRAPHIC EFFLUENTS  

Microsoft Academic Search

A method for radioassay of gas-liquid chromatographic effluents by ; scintiliation counting is described. A cartridge filled with anthracene crystals ; is used as a flow-through radiation detector. Upon leaving the column, the ; effluent is passed over hot copper oxide, which converts the organic materials to ; COâ and water. If tritium is to be counted, the water is

A. Karmen; I. McCaffrey; R. L. Bowman

1962-01-01

460

Methods of analysis-Determination of pesticides in sediment using gas chromatography/mass spectrometry  

USGS Publications Warehouse

A method for the determination of 119 pesticides in environmental sediment samples is described. The method was developed by the U.S. Geological Survey (USGS) in support of the National Water Quality Assessment (NAWQA) Program. The pesticides included in this method were chosen through prior prioritization. Herbicides, insecticides, and fungicides along with degradates are included in this method and span a variety of chemical classes including, but not limited to, chloroacetanilides, organochlorines, organophosphates, pyrethroids, triazines, and triazoles. Sediment samples are extracted by using an accelerated solvent extraction system (ASE®, and the compounds of interest are separated from co-extracted matrix interferences (including sulfur) by passing the extracts through high performance liquid chromatography (HPLC) with gel-permeation chromatography (GPC) along with the use of either stacked graphitized carbon and alumina solid-phase extraction (SPE) cartridges or packed Florisil®. Chromatographic separation, detection, and quantification of the pesticides from the sediment-sample extracts are done by using gas chromatography with mass spectrometry (GC/MS). Recoveries in test sediment samples fortified at 10 micrograms per kilogram (?g/kg) dry weight ranged from 75 to 102 percent; relative standard deviations ranged from 3 to 13 percent. Method detection limits (MDLs), calculated by using U.S. Environmental Protection Agency procedures (40 CFR 136, Appendix B), ranged from 0.6 to 3.4 ?g/kg dry weight.

Hladik, Michelle L.; McWayne, Megan M.

2012-01-01

461

Simultaneous Analysis and Quantification of Markers of Manjisthadi Churna Using High Performance Thin Layer Chromatography  

PubMed Central

Manjisthadi churna has been traditionally used in the Ayurvedic system of medicine and by traditional medical practices of India to treat hyperlipidemia. A rapid, simple and accurate method with high performance thin layer chromatography has been developed to standardised Manjisthadi churna using rubiadin, sennoside and ellagic acid as markers. Methanol extract of Manjisthadi churna were used for high performance thin layer chromatography on silica gel plates. The Rf of rubiadin, sennoside-A and ellagic acid were found to 0.48, 0.23 and 0.72, respectively with densitometric scanning at 280 nm and the calibration plot were linear in the range of 100-600 ng of markers. The correlation coefficients were higher than 0.99 were indicative of good linear dependence of peaks area on concentration. The rubiadin, sennoside-A and ellagic acid contents in Manjisthadi churna were found to be 0.014, 0.038 and 0.534% w/w, respectively. This method permits reliable quantification of rubiadin, sennoside-A and ellagic acid with good resolution and separation of the same from other constitutes of the extract of Manjisthadi churna. Recovery value from 95.66-102.33% showed the reliability and reproducibility of the method. The proposed high performance thin layer chromatography method for simultaneous quantification of markers in Manjisthadi churna can be used for routine quality testing. PMID:23901170

Patel, V. R.; Patel, R. K.

2013-01-01

462

Gas chromatography in space  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

463

High performance liquid chromatography  

SciTech Connect

A broad-based, general book on high performance liquid chromatography, designed to be a standard in the field. Written by contributors who work at the cutting edge of the science, this text/reference provides chromatographers, and teachers and students of analytical chemistry with comprehensive coverage of the theoretical bases for HPLC. Contributions explain terminology, thermodynamics and kinetics, detectors and derivatization, stationary phases, separations, equipment, error analysis, and advanced techniques, such as supercritical fluid chromatography and field flow fractionation.

Brown, P.; Hartwick, R.A.

1988-01-01

464

Headspace single-drop microextraction gas chromatography mass spectrometry for the analysis of volatile compounds from herba asari.  

PubMed

A rapid headspace single-drop microextraction gas chromatography mass spectrometry (SDME-GC-MS) for the analysis of the volatile compounds in Herba Asari was developed in this study. The extraction solvent, extraction temperature and time, sample amount, and particle size were optimized. A mixed solvent of n-tridecane and butyl acetate (1?:?1) was finally used for the extraction with sample amount of 0.750?g and 100-mesh particle size at 70°C for 15?min. Under the determined conditions, the pound samples of Herba Asari were directly applied for the analysis. The result showed that SDME-GC-MS method was a simple, effective, and inexpensive way to measure the volatile compounds in Herba Asari and could be used for the analysis of volatile compounds in Chinese medicine. PMID:23607049

Wang, Guan-Jie; Tian, Li; Fan, Yu-Ming; Qi, Mei-Ling

2013-01-01

465

Headspace Single-Drop Microextraction Gas Chromatography Mass Spectrometry for the Analysis of Volatile Compounds from Herba Asari  

PubMed Central

A rapid headspace single-drop microextraction gas chromatography mass spectrometry (SDME-GC-MS) for the analysis of the volatile compounds in Herba Asari was developed in this study. The extraction solvent, extraction temperature and time, sample amount, and particle size were optimized. A mixed solvent of n-tridecane and butyl acetate (1?:?1) was finally used for the extraction with sample amount of 0.750?g and 100-mesh particle size at 70°C for 15?min. Under the determined conditions, the pound samples of Herba Asari were directly applied for the analysis. The result showed that SDME-GC–MS method was a simple, effective, and inexpensive way to measure the volatile compounds in Herba Asari and could be used for the analysis of volatile compounds in Chinese medicine. PMID:23607049

Wang, Guan-Jie; Tian, Li; Fan, Yu-Ming; Qi, Mei-Ling

2013-01-01

466

Measurements of liquid-phase turbulence in gas-liquid two-phase flows using particle image velocimetry  

NASA Astrophysics Data System (ADS)

Liquid-phase turbulence measurements were performed in an air-water two-phase flow loop with a circular test section of 50 mm inner diameter using a particle image velocimetry (PIV) system. An optical phase separation method--planar laser-induced fluorescence (PLIF) technique—which uses fluorescent particles and an optical filtration technique, was employed to separate the signals of the fluorescent seeding particles from those due to bubbles and other noises. An image pre-processing scheme was applied to the raw PIV images to remove the noise residuals that are not removed by the PLIF technique. In addition, four-sensor conductivity probes were adopted to measure the radial distribution of the void fraction. Two benchmark tests were performed: the first was a comparison of the PIV measurement results with those of similar flow conditions using thermal anemometry from previous studies; the second quantitatively compared the superficial liquid velocities calculated from the local liquid velocity and void fraction measurements with the global liquid flow rate measurements. The differences of the superficial liquid velocity obtained from the two measurements were bounded within ±7% for single-phase flows and two-phase bubbly flows with the area-average void fraction up to 18%. Furthermore, a preliminary uncertainty analysis was conducted to investigate the accuracy of the two-phase PIV measurements. The systematic uncertainties due to the circular pipe curvature effects, bubble surface reflection effects and other potential uncertainty sources of the PIV measurements were discussed. The purpose of this work is to facilitate the development of a measurement technique (PIV-PLIF) combined with image pre-processing for the liquid-phase turbulence in gas-liquid two-phase flows of relatively high void fractions. The high-resolution data set can be used to more thoroughly understand two-phase flow behavior, develop liquid-phase turbulence models, and assess high-fidelity codes for multi-phase flows.

Zhou, Xinquan; Doup, Benjamin; Sun, Xiaodong

2013-12-01

467

[Research on diagnosis of gas-liquid detonation exhaust based on double optical path absortion spectroscopy technique].  

PubMed

The effect detection of detonation exhaust can provide measurement data for exploring the formation mechanism of detonation, the promotion of detonation efficiency and the reduction of fuel waste. Based on tunable diode laser absorption spectroscopy technique combined with double optical path cross-correlation algorithm, the article raises the diagnosis method to realize the on-line testing of detonation exhaust velocity, temperature and H2O gas concentration. The double optical path testing system is designed and set up for the valveless pulse detonation engine with the diameter of 80 mm. By scanning H2O absorption lines of 1343nm with a high frequency of 50 kHz, the on-line detection of gas-liquid pulse detonation exhaust is realized. The results show that the optical testing system based on tunable diode laser absorption spectroscopy technique can capture the detailed characteristics of pulse detonation exhaust in the transient process of detonation. The duration of single detonation is 85 ms under laboratory conditions, among which supersonic injection time is 5.7 ms and subsonic injection time is 19.3 ms. The valveless pulse detonation engine used can work under frequency of 11 Hz. The velocity of detonation overflowing the detonation tube is 1,172 m x s(-1), the maximum temperature of detonation exhaust near the nozzle is 2 412 K. There is a transitory platform in the velocity curve as well as the temperature curve. H2O gas concentration changes between 0-7% during detonation under experimental conditions. The research can provide measurement data for the detonation process diagnosis and analysis, which is of significance to advance the detonation mechanism research and promote the research of pulse detonation engine control technology. PMID:25208369

Lü, Xiao-Jing; Li, Ning; Weng, Chun-Sheng

2014-03-01

468

Column Chromatography  

NSDL National Science Digital Library

In this activity, learners separate the components of Gatorade using a home-made affinity column. In doing so, learners model the basic principle of affinity chromatography, a technique used to purify chemicals as well as bio-pharmaceuticals and petroleum products. This resource contains information about affinity chromatography and polarity.

Julie Yu

2007-01-01

469

Chromatography Theory  

NSDL National Science Digital Library

This site contains standard definitions related to chromatography similar to treatments found in analytical chemistry textbooks. It introduces the beginning student to Liquid Chromatography concepts relevant to biochemistry and includes a good example of choosing a mobile phase pH for a protein separation based on ion exchange.

470

Gas Chromatography.  

ERIC Educational Resources Information Center

This review covers fundamental developments in gas chromatography during 1982 and 1983. Literature is considered under these headings: columns; liguid phases; solid supports; sorption processes and solvents; open tubular column gas chromatography; instrumentation; high-resolution columns and applications; other techniques; qualitative and…

Karasek, Francis W.; And Others

1984-01-01

471

Analysis of Essential Oil in Jerusalem Artichoke (Helianthus tuberosus L.) Leaves and Tubers by Gas Chromatography-Mass Spectrometry  

PubMed Central

Purpose: To investigate, for the first time, the chemical composition of essential oil of the tubers and leaves of Jerusalem artichoke (Helianthus tuberosus L.), a species of sunflower native to eastern North America, growing in Ukraine. Methods: A hydrodistillation apparatus was used for the extraction of volatile components and then it was analysed by gas chromatography equipped with a split-splitless injector (split ratio, 1:50) and flame ionization detector (FID). The oil was analyzed under linear temperature programming applied at 4°C/min from 50°C - 340°C. Temperatures of the injector and FID detector were maintained at 280°C and 300°C, respectively. The chemical analysis of the oil was carried out using gas chromatography coupled to mass spectrometry (GC-MS), to determine the chemical composition of the volatile fraction. Results: The essential oils content ranged from 0.00019 to 0.03486 and 0.00011 to 0.00205 (g/100g), in leaves and tubers, respectively. The qualitative and quantitative analysis led to the identification of 17 components in both species samples. The major component found in leaves and tubers was (-)-?-bisabolene with 70.7% and 63.1%, respectively. Conclusion: Essential oil profile of Jerusalem artichoke species showed significant differences between leaves and tubers species. Additionally, the leaves of Jerusalem artichoke are a promising source of natural ?-bisabolene. PMID:25671184

Helmi, Zead; Al Azzam, Khaldun Mohammad; Tsymbalista, Yuliya; Ghazleh, Refat Abo; Shaibah, Hassan; Aboul-Enein, Hassan

2014-01-01

472

An Ultra-Trace Analysis Technique for SF6 Using Gas Chromatography with Negative Ion Chemical Ionization Mass Spectrometry.  

PubMed

Sulfur hexafluoride (SF6) is widely used as a tracer gas because of its detectability at low concentrations. This attribute of SF6 allows the quantification of both small-scale flows, such as leakage, and large-scale flows, such as atmospheric currents. SF6's high detection sensitivity also facilitates greater usage efficiency and lower operating cost for tracer deployments by reducing quantity requirements. The detectability of SF6 is produced by its high molecular electronegativity. This property provides a high potential for negative ion formation through electron capture thus naturally translating to selective detection using negative ion chemical ionization mass spectrometry (NCI-MS). This paper investigates the potential of using gas chromatography (GC) with NCI-MS for the detection of SF6. The experimental parameters for an ultra-trace SF6 detection method utilizing minimal customizations of the analytical instrument are detailed. A method for the detection of parts per trillion (ppt) level concentrations of SF6 for the purpose of underground ventilation tracer gas analysis was successfully developed in this study. The method utilized a Shimadzu gas chromatography with negative ion chemical ionization mass spectrometry system equipped with an Agilent J&W HP-porous layer open tubular column coated with an alumina oxide (Al2O3) S column. The method detection limit (MDL) analysis as defined by the Environmental Protection Agency of the tracer data showed the method MDL to be 5.2 ppt. PMID:25452581

Jong, Edmund C; Macek, Paul V; Perera, Inoka E; Luxbacher, Kray D; McNair, Harold M

2014-12-01

473

Structural analysis of the extracellular polysaccharide produced by Sphaerotilus natans.  

PubMed

An extracellular polysaccharide (EPS) was recovered and purified from the culture fluid of a sheathed bacterium, Sphaerotilus natans. Glucose, rhamnose, and aldobiouronic acid were detected in the acid hydrolysate of EPS by thin-layer chromatography (TLC). The aldobiouronic acid was found to be composed of glucuronic acid and rhamnose by TLC and gas-liquid chromatography analyses of the corresponding neutral disaccharide. The structure of EPS was identified by methylation linkage analysis and nuclear magnetic resonance. Additionally, partial acid hydrolysates of EPS were prepared and put through fast atom bombardment-mass spectrometry to determine the sugar sequence of EPS. The resulting data showed that EPS produced by S. natans is a new gellan-like polysaccharide constructed from a tetrasaccharide repeating unit, as shown below. -->4)-alpha-D-Glcp-(1-->2)-beta-D-GlcA p-(1-->2)-alpha-L-Rha p-(1-->3)-beta-L-Rha p-(1-->. PMID:12224639

Takeda, Minoru; Nomoto, Shogo; Koizumi, Jun-ichi

2002-07-01

474

A simplified radioimmunoassay of plasma nortriptyline in depressed patients compared with high-pressure liquid chromatography and gas-liquid chromatography  

Microsoft Academic Search

Antiserum to nortriptyline was generated in male New Zealand rabbits innoculated with n-succinylnortriptyline-bovine serum albumin conjugates. The antiserum was used at a final dilution of 1:4000 and tritiated imipramine was used as the label antigen. An accurate, sensitive, and specific radioimmunoassay of depressed patients' plasma or serum nortriptyline is described. The accuracy was good with a recovery range of 90–100%

Joseph F. Sayegh

1986-01-01

475

Ultra-Trace Analysis of Nine Macrolides, including Tulathromycin A (Draxxin), in Edible Animal Tissues with Mini-Column Liquid Chromatography Tandem Mass Spectrometry  

Technology Transfer Automated Retrieval System (TEKTRAN)

Analysis of 9 macrolides is presented, including tulathromycin A (Draxxin), in beef, poultry and pork muscle with a simple multi-residue extraction and analysis method using high performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry. The extraction method inv...

476

Ion Exchange Chromatography and Mass Spectrometric Methods for Analysis of Cadmium-Phytochelatin (II) Complexes  

PubMed Central

In this study, in vitro formed Cd-phytochelatin (PC2) complexes were characterized using ion exchange chromatography (IEC) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The ratio of both studied compounds as well as experimental conditions were optimized. The highest yield of the complex was observed under an applied concentration of 100 µg·mL?1 PC2 and 100 µg·mL?1 of CdCl2. The data obtained show that IEC in combination with MALDI-TOF is a reliable and fast method for the determination of these complexes. PMID:23538727

Merlos Rodrigo, Miguel Angel; Cernei, Natalia; Kominkova, Marketa; Zitka, Ondrej; Beklova, Miroslava; Zehnalek, Josef; Kizek, Rene; Adam, Vojtech

2013-01-01

477

Analysis of benzo(a)pyrene in airborne particulates by gas chromatography  

NASA Technical Reports Server (NTRS)

A routine method was developed to measure benzo(a)pyrene in airborne particulates. Samples were collected on a filter and the organic portion was extracted with cyclohexane. The polynuclear hydrocarbon (PNHC) fraction was separated from the aliphatics by column chromatography. An internal standard was added to the extract and a portion of it was injected into a gas chromatograph. Although the gas chromatographic method has often been reported in the literature, satisfactory separation of benzo(a)pyrene and benzo(e)pyrene has not been achieved. With the introduction of a nematic liquid crystal as the stationary phase good separation is now possible.

Luedecke, E.

1976-01-01

478

Different headspace solid phase microextraction--gas chromatography/mass spectrometry approaches to haloanisoles analysis in wine.  

PubMed

Three approaches in determination of six haloanisoles (2,4,6-trichloroanisole, 2,3,4-trichloroanisole, 2,3,6-trichloroanisole, tetrachloroanisole, pentachloroanisole and 2,4,6-tribromoanisole) in wine were compared. Comprehensive gas chromatography - time of flight mass spectrometry (GC×GC-ToF-MS) was described for the first time for this application and compared to gas chromatography-tandem mass spectrometry (GC-MS/MS) using triple quadrupole instrument. These techniques were compared with "standard" analytical approach using GC-MS(SIM). SPME method was developed and used for all separation methods (DVB/PDMS fiber, 70 °C, 30%NaCl, 20 min extraction). Extraction dependence on matrix was discussed using model wines with different ethanol contents (8%, 12%, and 18%) as well as water and different wines (dry white, dry red and sweet liqueur), with the lowest sensitivities obtained for highest ethanol contents in model wine and for liqueur wine. Limits of detection for GC×GC-ToF-MS method were 0.09-2.92 ng/L depending on the examined compound and matrix (compared to 0.1-13.3 ng/L obtained using GC/MS(SIM)). For GC-MS/MS method lower detection limits were achieved than for the GC×GC method (0.01-0.1 ng/L), however comprehensive gas chromatography-mass spectrometry provides full spectral information on analyzed compounds. Both methods had limits of detection far below odor thresholds of haloanisoles in wine, good linearity up to 2000 ng/L tested and good precision, what makes them suitable for analysis of these compounds in low ppt levels. PMID:23932370

Jele?, Henryk H; Dziadas, Mariusz; Majcher, Ma?gorzata

2013-10-25

479

Validated fluorimetric HPLC analysis of acetaldehyde in hemoglobin fractions separated by cation exchange chromatography: three new peaks associated with acetaldehyde.  

PubMed

Stable hemoglobin-acetaldehyde adducts present in hemoglobin fractions separated by polyaspartic acid cation exchange chromatography were quantified by fluorimetric HPLC. The fluorescent species eluted from the HPLC was confirmed by mass spectrometry to be consistent with the expected product from reaction of acetaldehyde, 1,3-cyclohexanedione (CHD), and ammonium ion. Hemolysate (2.2 mM hemoglobin) was incubated in equivalent volumes of either phosphate-buffered saline or 5 mM acetaldehyde at 37 degrees C for 30 min and washed three times with H2O to remove free acetaldehyde and labile adducts before the injection of 14.7 mg hemoglobin onto the cation exchange column. Fluorimetric HPLC analysis of hemolysate samples either with or without in vitro reaction with acetaldehyde revealed that most acetaldehyde resides in the hemoglobin A0 fraction. The reaction with acetaldehyde in vitro resulted in a significant increase in fast-eluting minor hemoglobin species on cation exchange chromatography concomitant with increased acetaldehyde in the HbA1a+b, HbA1c, and HbA1-AcH fractions. We report three new cation exchange chromatographic peaks after reaction with acetaldehyde: HbA1-AcH-3, HbA1c-1, and HbA0-1. Each new peak was found to associate with a significant quantity of CHD-reactive acetaldehyde. These experiments provide additional evidence that stable adducts form between acetaldehyde and hemoglobin and that these adducts occur in multiple hemoglobin species separated by cation exchange chromatography. Further characterization and structural assignment of these species are warranted in view of their potential utility as markers for ethanol intake. PMID:7485842

Chen, H M; Scott, B K; Braun, K P; Peterson, C M

1995-08-01

480

Floral classification of honey using liquid chromatography-diode array detection-tandem mass spectrometry and chemometric analysis.  

PubMed

A high performance liquid chromatography-diode array detection-tandem mass spectrometry (HPLC-DAD-MS/MS) method for the floral origin traceability of chaste honey and rape honey samples was firstly presented in this study. Kaempferol, morin and ferulic acid were used as floral markers to distinguish chaste honey from rape honey. Chromatographic fingerprinting at 270 nm and 360 nm could be used to characterise chaste honey and rape honey according to the analytical profiles. Principal component analysis (PCA), partial least squares (PLS), partial least squares-discrimination analysis (PLS-DA) and soft independent modeling of class analogy (SIMCA) were applied to classify the honey samples according to their floral origins. The results showed that chaste honey and rape honey could be successfully classified by their floral sources with the analytical methods developed through this study and could be considered encouraging and promising for the honey traceability from unifloral or multifloral nectariferous sources. PMID:24128567

Zhou, Jinhui; Yao, Lihu; Li, Yi; Chen, Lanzhen; Wu, Liming; Zhao, Jing

2014-02-15

481

Analysis of bitter limonoids in citrus juices by atmospheric pressure chemical ionization and electrospray ionization liquid chromatography-mass spectrometry.  

PubMed

Improved analytical techniques for bitter limonoids in citrus and citrus juices can expedite the evaluation of freeze-induced citrus damage for citrus growers and juice quality for citrus juice producers. Microbore normal-phase and reverse-phase chromatography coupled to a mass spectrometer operating in a positive ion atmospheric pressure chemical ionization and electrospray ionization modes were found to be rapid, selective, and sensitive methods for the analysis of the bitter limonoids limonin and nomilin in citrus juices. Analysis was performed on a chloroform extract of citrus juice to which an internal standard was added. The methods are capable of detecting citrus limonoids in citrus juice in the 60-200 picogram range and quantifying citrus juice limonoids in concentrations as low as 120 picograms. An accurate "total limonoid bitterness" in citrus juice, as represented by the combined occurrence of limonin and nomilin, is easily determined by these methods. PMID:12797731

Manners, Gary D; Breksa, Andrew P; Schoch, Thomas K; Hidalgo, Marlene B

2003-06-18

482

Challenges in the development of bioanalytical liquid chromatography-mass spectrometry method with emphasis on fast analysis.  

PubMed

The development of bioanalytical methods has become more and more challenging over the past years due to very demanding requirements in terms of method reliability, sensitivity, speed of analysis and sample throughput. LC-MS/MS has established itself as a method of choice for routine analysis of biological materials. A development of such method consists of several steps including sample preparation and clean-up step, efficient chromatographic separation, sensitive and selective detection of analytes in complex matrices, a choice of convenient data processing and calibration approach and finally method validation. Each of these steps has its own constraints and challenges, which are discussed in detail in this review. Novel and modern approaches in sample preparation, chromatography and detection are especially emphasized. Attention is paid to proper calibration approach and matrix effects that can seriously affect method accuracy and precision. PMID:22999195

Nováková, Lucie

2013-05-31

483

The Analysis of Orange Oil and the Aqueous Solubility of d-Limonene. Two Complementary Gas Chromatography Experiments  

NASA Astrophysics Data System (ADS)

The monoterpene d-limonene is determined by gas chromatography using anisole as the internal standard. Unknowns for the