These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
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

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

3

Triglyceride analysis by consecutive liquid-liquid partition and gas-liquid chromatography. Ephedra nevadensis seed fat  

Microsoft Academic Search

The triglyceride composition ofEphedra nevadensis seed fat, which contains 16 different fatty acids, has been analyzed by a combination of liquid-liquid partition and gas-liquid\\u000a chromatography. Triglycerides were first separated by liquid-liquid partition chromatography. The recovered fractions were\\u000a then analyzed by gas-liquid chromatography to determine the molecular weights of the triglycerides present. Consecutive separation\\u000a by these two techniques resolved this complex

Carter Litchfield

1968-01-01

4

Simulating retention in gas-liquid chromatography  

SciTech Connect

Accurate predictions of retention times, retention indices, and partition constants are a long sought-after goal for theoretical studies in chromatography. Configurational-bias Monte Carlo (CBMC) simulations in the Gibbs ensemble using the transferable potentials for phase equilibria-united atom (TraPPE-UA) force field have been carried out to obtain a microscopic picture of the partitioning of 10 alkane isomers between a helium vapor phase and a squalane liquid phase, a protypical gas-liquid chromatography system. The alkane solutes include some topological isomers that differ only in the arrangement of their building blocks (e.g., 2,5-dimethylhexane and 3,4-dimethylhexane), for which the prediction of the retention order is particularly difficult. The Kovats retention indices, a measure of the relative retention times, are calculated directly from the partition constants and are in good agreement with experimental values. The calculated Gibbs free energies of transfer for the normal alkanes conform to Martin's equation which is the basis of linear free energy relationships used in many process modeling packages. Analysis of radial distribution functions and the corresponding energy integrals does not yield evidence for specific retention structures and shows that the internal energy of solvation is not the main driving force for the separation of topological isomers in this system.

Martin, M.G.; Siepmann, J.I.; Schure, M.R.

1999-12-16

5

Analysis of short-chain acids from bacteria by gas-liquid chromatography with a fused-silica capillary column.  

PubMed Central

The use of a flexible, fused-silica capillary column for gas-liquid chromatographic analysis of short-chain acids from bacteria is illustrated with a standard acid mixture and with a derivatized extract of culture medium from Clostridium difficile. PMID:7068826

Moss, C W; Nunez-Montiel, O L

1982-01-01

6

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

Code of Federal Regulations, 2011 CFR

...2011-04-01 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...

2011-04-01

7

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

Code of Federal Regulations, 2012 CFR

...2012-04-01 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...

2012-04-01

8

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

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Gas liquid chromatography system for clinical...Laboratory Instruments § 862.2250 Gas liquid chromatography system for clinical use. (a) Identification. A gas liquid chromatography system for...

2010-04-01

9

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

Code of Federal Regulations, 2013 CFR

...2013-04-01 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...

2013-04-01

10

Determination of cellular fatty acid compositions of various yeasts by gas-liquid chromatography.  

PubMed Central

The cellular fatty acid composition of 51 cultures of various species of yeasts was determined by gas-liquid chromatography. Analysis was done with a fused-silica gas-liquid chromatography capillary column, with resolution of all components including mono-, di-, and tri-unsaturated 18-carbon acids. The cultures were placed into one of four distinct gas-liquid chromatography groups on the basis of large quantitative differences in fatty acids. Group I contained only Saccharomyces species and group II only Torulopsis glabrata. Most Candida species were placed into group III, and group IV contained only basidiomycetous yeasts. PMID:7161374

Moss, C W; Shinoda, T; Samuels, J W

1982-01-01

11

Extraction and liquid-solid chromatography cleanup procedures for the direct analysis of four pyrethroid insecticides in crops by gas--liquid chromatography.  

PubMed

The extraction of four pyrethroid insecticides, fenpropanate (WL 41706, S-3206), permethrin (WL 43479, FMC-33297, PP 557, NRDC-143), cypermethrin (WL 43467, NRDC 149), and fenvalerate (WL 43775, S-5602) from carrots, tomatoes celery, and onions with acetone followed by extraction of the resulting acetone--water mixture with hexane, was investigated and found suitable for residue analysis. The elution of the four materials from two types of silica and alumina absorbents with mixtures of organic solvents of varying polarity was examined. The elution patterns and recoveries from silica gel, aluminum oxide, and water deactivated Florisil indicated potential utility in cleanup. Florisil was found to provide cleanup for asparagus, carrots, tomatoes, tobacco, and onions permitting analyses to less than 0.01 ppm for most of the insecticides by electron capture gas--liquid chromatography, at extract concentrations of 1 g/ml. The other adsorbents, singly or in combination, were found to provide the cleanup required for radishes and those cases involving other crops where Florisil cleanup was insufficient. PMID:748360

Chapman, R A; Harris, C R

1978-12-11

12

Temperature Gradient Method for Continuous Countercurrent Gas–Liquid Chromatography  

Microsoft Academic Search

Continuous countercurrent gas–liquid chromatography (CCGLC), where the gas and liquid phases move countercurrently and the sample can be introduced continuously, is a method suitable for separating binary sample systems. The flow ratio of the gas and liquid phases (G\\/L) in CCGLC should be between the partition coefficients of the two components to be separated. However, the larger the difference between

Katsuya Sato; Osamu Motokawa; Katsunori Watabe; Toshihide Ihara; Toshiyuki Hobo

1993-01-01

13

Evaluation of gas-liquid chromatography for the rapid diagnosis of Clostridium difficile associated disease.  

PubMed

Direct gas-liquid chromatography of faecal specimens with isocaproic acid as a marker was used for the rapid diagnosis of Clostridium difficile associated diarrhoeal diseases. Ninety stools were examined and results were compared with conventional culture on selective medium and cytotoxin assay in tissue culture. Using a combined analysis of isocaproic acid and butyric acid peak heights we defined three categories: positive, negative, and indeterminate. When the indeterminate group was excluded, the positive and negative predictive values of gas-liquid chromatography analysis were 86.9% and 85% respectively compared with culture and 71.4% and 95% respectively compared with cytotoxin assay. PMID:4008667

Gianfrilli, P; Pantosti, A; Luzzi, I

1985-06-01

14

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

15

Analysis of metabolic profiles of steroids in faeces of healthy subjects undergoing chenodeoxycholic acid treatment by liquid-gel chromatography and gas-liquid chromatography-mass spectrometry.  

PubMed

The multicomponent analysis of faecal steroids is described. Steroids were removed from faeces by solvent stripping in a Soxhlet apparatus and the resulting extracts were fractionated by diethylaminohydroxypropyl Sephadex column chromatography into neutral sterols, free bile acids, glycine conjugated bile acids, taurine conjugated bile acids and sulphated steroids. In this study the method has been applied for faecal steroid analyses of healthy subjects undergoing chenodeoxycholic acid therapy. Chenodeoxycholic acid administration causes a considerable increase in the concentration of faecal lithocholic acid which is a known comutagenic bile acid. Furthermore it has been shown that conjugated bile acids can account for between 10 and 20% of the faecal bile acid pool. The method described is convenient and may be useful for epidemiological studies which require a large number of faecal samples to be analysed. PMID:6513557

Owen, R W; Thompson, M H; Hill, M J

1984-11-01

16

Agar medium for gas-liquid chromatography of anaerobes.  

PubMed

This study evaluates a method of performing gas-liquid chromatography (GLC) by direct extraction of fatty acids from agar for identification of clinically significant anaerobic bacteria. The potential use of agar cultures for GLC was studied by comparing chromatograms of 117 clinically isolated anaerobes grown in peptone yeast glucose broth and chopped meat carbohydrate broth, and on enriched brucella blood agar. For 98 of 117 anaerobes, fatty acid patterns from agar cultures were similar to those in broth. Significant differences were only found with Streptococcus intermedius, Clostridium perfringens, Clostridium tertium, and Actinomyces species, which produced less of certain fatty acids on agar than in broth. Results of this study indicate that GLC of short chain fatty acids produced on agar medium by anaerobes, combined with simple tests such as Gram's stain and colonial morphology, may allow fir direct presumptive genus identification from an initial pure agar culture. PMID:3940426

Pankuch, G A; Appelbaum, P C

1986-01-01

17

Combining NMR Spectroscopy and Gas-Liquid Chromatography for Analysis of the Fatty Acid Composition of Fenugreek Seed Oil (Trigonella foenum graecum L.)  

NASA Astrophysics Data System (ADS)

1H and 13C NMR spectroscopy established that fenugreek seed oil consists mainly of triacylglycerides. Oleic and linoleic acids are found preferentially in the 2 position and ?-linolenic acid is found preferentially in the 1,3 positions of the glycerol backbone. By combining NMR and gas-liquid chromatography, we have shown that fenugreek seeds contain 5.5 %-6.8 % oil, consisting mainly of unsaturated fatty acids (68.2 %-82.1 %): linoleic (31.3 %-46.8 %), ?-linolenic (15.1 %-36.6 %), and oleic (11.6 %-21.3 %). The highest unsaturated fatty acid content is found in the cultivars D-19, Ovary Gold, Blidet, Ovary 4 and the lowest fatty acid content is found in the Metha cultivar. The percentage of polyunsaturated fatty acids is higher in oils of fenugreek cultivars from northern regions (Belarus, Hungary, France).

Skakovskii, E. D.; Tychinskaya, L. Yu.; Mauchanava, V. A.; Karankevich, E. G.; Lamotkin, S. A.; Ahabalayeva, A. D.; Reshetnikov, V. N.

2013-11-01

18

Identification of Clinical Isolates of Mycobacteria with Gas-Liquid Chromatography Alone  

PubMed Central

Identification of 18 mycobacterial species was performed by analysis of profiles obtained by using gas-liquid chromatography. Organisms were saponified in methanolic NaOH, and the reaction mixture was treated with BF3 in methanol and extracted with a hexane-chloroform mixture. An identification scheme was developed from 128 stock strains and tested against a collection of 79 clinical isolates. By using gas-liquid chromatographic profiles alone, 58% of specimens were correctly identified to species level, and an additional 41% were correctly identified to a group of two or three organisms. Use in a clinical laboratory over a 2-month period proved chromatography to be as accurate as and more rapid than concurrent biochemical testing. Of 81 isolates tested, 64% were identified to species level by chromatography alone. An additional 35% were differentiated to the same groups of two or three organisms as found in our analysis of stock strains. These groups consisted of: Mycobacterium tuberculosis, M. bovis, and M. xenopi; M. avium complex, M. gastri, and M. scrofulaceum; or M. fortuitum and M. chelonei. Identification to species level from these groups could usually be done by colonial morphology alone and could always be done by the addition of one selected biochemical test. This study demonstrated the practical application of gas-liquid chromatography in the identification of mycobacteria in a clinical laboratory. In particular, all strains of M. gordonae and M. kansasii were identified to species level. M. tuberculosis was definitively identified in 85% of cases. When it could not be definitely identified, the only alternatives were M. bovis and M. xenopi, both of which are rare causes of infection. PMID:118984

Tisdall, Philip A.; Roberts, Glenn D.; Anhalt, John P.

1979-01-01

19

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

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

Differentiation of Salmonella Serotypes by pyrolysis-gas-liquid chromatography of cell fragments.  

PubMed Central

Pyrolysis-gas-liquid chromatography (PGLC) of whole cells and cell fragments was used to differentiate 10 Salmonella serotypes. Lyophilized samples (200 microgram) of whole cells, cell walls, flagella, and deoxyribonucleic acid from each serotype were analyzed in duplicate by PGLC. Pyrochromatograms recorded as pyrolytic elution patterns represented thermal fragmentation products of the samples. Mathematical expressions of percent similarity and percent conformity were calculated for all possible pair combinations of the 10 serotypes. Stepwise discriminant analysis of the PGLC data showed that 100 percent correct classification of the 10 serotypes was possible from the flagella or deoxyribonucleic acid pyrochromatograms. The classification matrix of the whole-cell data showed a 90 percent correct classification. PGLC of cell fragments may provide useful information for taxonomic studies of Salmonella and other microorganisms. PMID:623477

Emswiler, B S; Kotula, A W

1978-01-01

22

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

23

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...

24

Investigation of the composition of coking naphthalene impurities by gas-liquid chromatography  

SciTech Connect

An investigation of the impurities present in marketable naphthalene was presented. The concentrations of the impurities were determined by gas-liquid chromatography. Three different types of naphthalene fractions were tested--fusion, pressed, and centrifuged. It was determined that the total concentration of impurities reached 0.20-0.25 wt.%. Also, the pressed and fusion naphthalenes contained benzonitrile, dimethylnaphthalenes, diphenyl, acenaphthene, and diphenyleneoxide, which were not present in the centrifuged naphthalene.

Nabivach, V.M.; Gerasimenko, V.A.; Ryabozad, A.S.; Voitenko, B.I.; Grumberg, L.R.; Chernyshov, Y.A.; Shvarts, S.G.

1982-01-01

25

Investigation of the composition of coking naphthalene impurities by gas-liquid chromatography  

Microsoft Academic Search

An investigation of the impurities present in marketable naphthalene was presented. The concentrations of the impurities were determined by gas-liquid chromatography. Three different types of naphthalene fractions were tested--fusion, pressed, and centrifuged. It was determined that the total concentration of impurities reached 0.20-0.25 wt.%. Also, the pressed and fusion naphthalenes contained benzonitrile, dimethylnaphthalenes, diphenyl, acenaphthene, and diphenyleneoxide, which were not

V. M. Nabivach; V. A. Gerasimenko; A. S. Ryabozad; B. I. Voitenko; L. R. Grumberg; Y. A. Chernyshov; S. G. Shvarts

1982-01-01

26

Detection of Clostridium difficile from an enhancement broth by gas-liquid chromatography.  

PubMed

Gas-Liquid chromatography (GLC) was used to detect the presence of isocaproic acid produced by Clostridium difficile from 54 stool samples grown in cycloserine-cefoxitin broth. Isocaproic acid was detected in 12 samples of which 5 were confirmed to be Clostridium difficile by culture and biochemical tests. The detection of isocaproic acid by GLC together with the presence of presumptive colonies on primary selective culture media provides a more rapid laboratory diagnosis for Clostridium difficile. PMID:1795558

Hassan, H; Cheng, S C

1991-06-01

27

Determination of interaction second virial coefficients for the CO?-H?O system using gas-liquid chromatography  

E-print Network

DETERMINATION OF INTERACTION SECOND VIRIAL COEFFICIENTS FOR THE CO~ ? H20 SYSTEM USING GAS ? LIQUID CHROMATOGRAPHY A Thesis by KEITH NOLAN ROGERS Submitted to the Graduate College of Texas A&M University in partial fulfillment... of the requirement for the degree o. MASTER OF SCIENCE December 1979 Major Subject: Chemical Engineering DETERMINATION OF INTERACTION SECOND VIRIAL COEFFICIENTS FOR THE CO ? H 0 SYSTEM USING GAS ? LIQUID CHROMATOGRAPHY A Thesis by KEITH NOLAN ROGERS...

Rogers, Keith Nolan

2012-06-07

28

Detection of Clostridium difficile in faeces by direct gas liquid chromatography.  

PubMed

Stool specimens examined for the presence of Clostridium difficile and its cytotoxin were screened by gas liquid chromatography for the presence of volatile fatty acids and p-cresol. Twenty seven of 110 (25%) stools yielded C difficile or cytotoxin; iso-valeric acid was detected in 63/110 (57%) and iso-caproic acid in 18/110 (16%) stools. Para-cresol was found in 24/71 (34%) stools examined. Iso-valeric acid was detected in 85% of stools positive for C difficile, whereas iso-caproic acid (41%) and p-cresol (52%) were found in much lower numbers of C difficile-positive stools. It is concluded that gas chromatographic detection of volatile fatty acids or p-cresol in faeces are not satisfactory screening tests for the presence of C difficile. PMID:6693575

Levett, P N

1984-02-01

29

Solvation parameters. Part 5: Physicochemical interpretation of experimental solvent values for stationary phases of gas–liquid chromatography  

Microsoft Academic Search

It has been demonstrated for a long time that in the particular case of gas–liquid chromatography (GLC), a linear free energy relationship (LFER) of five terms can be established, each term including a parameter of solute and a parameter of solvent. The nature of some of these parameters has been quite clearly identified, even if not always well predicted from

P. Laffort

2011-01-01

30

The detection and determination of some chlorinated pesticide residues in crops, soils and animal tissues by gas-liquid chromatography  

Microsoft Academic Search

Summary A rapid method for the identification and determination of traces of chlorinated pesticides in crops, soils and animal tissues by gas-liquid chromatography with electron capture ionisation detection will be outlined. Only conventional G. L. C. equipment is required and neither preliminary „clean-up” nor concentration of the extract solution of the pesticide is, in general, necessary. In most cases the

R. Goulden

1964-01-01

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

Rapid differentiation of bacterial meningitides by direct gas-liquid chromatography.  

PubMed Central

Rapid identification of Haemophilus influenzae and other bacillary meningitides was attempted by gas-liquid chromatography (GLC) of the metabolic by-products in broth cultures and in cerebrospinal fluid (CSF) samples obtained from experimental meningitis produced in New Zealand White male rabbits. These results were correlated with the GLC of CSF of meningitis patients. A major peak with retention time of succinic acid was found in the broth cultures of all bacilli tested including H. influenzae, Escherichia coli, Enterobacter cloacae, Klebsiella pneumoniae, Proteus mirabilis, Citrobacter freundii, Pseudomonas aeruginosa, and Listeria monocytogenes. Succinic acid was also found in the CSF of experimental meningitis and in the CSF of all patients with H. influenzae and Esch. coli meningitis. This peak was not detected in the blood samples of experimental animals. It was also absent in the broth cultures of all of the gram-positive and gram-negative cocci tested, such as Streptococcus pneumoniae and Neisseria meningitidis. Succinic acid, which appears to be a by product of fermentation, persisted as a clear cut marker in H. influenzae meningitis for at least 3 d after the initiation of treatment. In one patient, the succinic acid peak disappeared during treatment and reappeared with a clinical relapse. Clearly, the presence of succinic acid that can be rapidly detected by GLC in the CSF excludes pneumococcal or meningococcal meningitis and strongly suggests H. influenzae or other bacillary meningitides. PMID:7042759

Thadepalli, H; Gangopadhyay, P K; Ansari, A; Overturf, G D; Dhawan, V K; Mandal, A K

1982-01-01

33

Identification of Clostridium difficile in stool specimens by culture-enhanced gas-liquid chromatography.  

PubMed Central

We have developed a sensitive and specific method for the identification of Clostridium difficile in stool specimens based on the detection of metabolic breakdown products of the organism by gas-liquid chromatography after incubation of stool samples in a selective broth medium containing cefoxitin. Use of this approach to test samples from two different populations of patients at separate medical centers showed this method to be superior to plate cultures or cytotoxin testing alone for both populations. The combined results from the two patient populations showed that 225 of 226 confirmed isolates were identified correctly, resulting in a sensitivity of 99.6% and a specificity of 99.0%. This method eliminates the delay caused by subculturing for tests requiring a pure isolate. The culture phase amplifies even low numbers of C. difficile in fecal samples (due to low in vivo concentrations or delayed transport) and thus increases sensitivity. Other advantages include the ability to detect C. difficile in the mixed flora of the stool and the ability of most clinical laboratories to use this procedure. Given the complexities of the detection of C. difficile toxins and the increasing importance of this organism as a nosocomial agent, culture-based methods remain the preferred approach to screening and routine workup for cases of diarrhea. PMID:2685021

Johnson, L L; McFarland, L V; Dearing, P; Raisys, V; Schoenknecht, F D

1989-01-01

34

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

35

Identifying Mycobacterium tuberculosis cultures by gas-liquid chromatography and a computer-aided pattern recognition model.  

PubMed Central

A procedure that uses gas-liquid chromatography and a pattern recognition computer model was developed for distinguishing cultures of Mycobacterium tuberculosis from cultures of other mycobacteria, common bacteria, and fungi. In this procedure, a sample of a culture preparation is methanolyzed and trimethylsilylated sequentially and injected into a gas chromatograph equipped with a flame ionization detector. A pattern recognition procedure computes an error score by comparing the gas-liquid chromatography peak responses of a culture to those of a standard M. tuberculosis culture. Ten M. tuberculosis cultures were used in the development of the pattern recognition model. Computed error scores of 5 or less were established for identifying an M. tuberculosis culture. The method was evaluated with two sets of test samples, non-M. tuberculosis and M. tuberculosis cultures. Sample identification was correct for all 14 M. tuberculosis cultures (M. tuberculosis or non-M. tuberculosis), 45 fungal cultures, 94 bacterial cultures, and all but 1 of 18 cultures of mycobacteria other than tuberculosis (MOTT). The false prediction represented an isolate of M. fortuitum. For M. tuberculosis, fungal, bacterial, and MOTT cultures, the ranges of error scores were 1 to 5, 16 to 33, 13 to 34, and 4 to 26, respectively. Therefore, we have demonstrated that this diagnostic model can distinguish M. tuberculosis from non-M. tuberculosis cultures with a high degree of accuracy. PMID:3125216

Maliwan, N; Reid, R W; Pliska, S R; Bird, T J; Zvetina, J R

1988-01-01

36

Free amino acids in bee hive product (propolis) as identified and quantified by gas-liquid chromatography.  

PubMed

Propolis is a natural resinous product collected by honey bees and containing, among other biochemical constituents, a variety of free amino acids. Acid extraction and quantification of these amino acids by gas-liquid chromatography reveals that their total concentration in this honey bee product is over 40% w/w, and that arginine and proline constitutes over 50% of the crude acid extract. As propolis was shown to stimulate mammalian tissue regeneration, we suggest that the physiological significance of arginine in the propolis product lies in its ability to stimulate mitosis and to enhance protein biosynthesis, and that the biochemical importance of proline in it, stems from its capability to promote build-up of collagen and elastin, two essential components in the matrix of connective tissues. PMID:3749241

Gabrys, J; Konecki, J; Krol, W; Scheller, S; Shani, J

1986-06-01

37

Analyses of fermentation products of Listeria species by frequency-pulsed electron-capture gas-liquid chromatography.  

PubMed

Aerobic fermentation broths of eight Listeria monocytogenes strains, two or more strains of the remaining six Listeria species, and one strain of Jonesia denitrificans were examined by frequency-pulsed electron-capture gas-liquid chromatography for carboxylic acids, alcohols, amines, and hydroxy acids. All species produced acetic, isobutyric, butyric, isovaleric, phenylacetic, lactic, 2-hydroxybutyric, 2-hydroxyvaleric, and 2-hydroxyisocaproic acids. Propionic acid was not formed, and traces of isocaproic acid were observed. Of the alcohol and amine derivatives observed, only acetylmethylcarbinol, butylamine, and putrecine were identified. Recognition of the products of glucose and amino acid metabolism serves to further characterize the members of the genus Listeria both taxonomically and physiologically. PMID:2510917

Daneshvar, M I; Brooks, J B; Malcolm, G B; Pine, L

1989-08-01

38

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

39

Gas liquid chromatographic analysis of hydroxy fatty acids, as their trimethylsilyl ether derivatives  

Microsoft Academic Search

A quantitative method is described for the rapid gas liquid chromatographic analysis of mono- and polyhydroxystearates as\\u000a their trimethylsilyl (TMS) ether derivatives. The TMS derivatives of the hydroxy esters are formed rapidly and quantitatively\\u000a at room temp. The retention times of ricinoleic acid as the methyl ester, acetylated derivative and the TMS derivative are\\u000a compared. Purified diastereoisomers of di-, triand

R. D. Wood; P. K. Raju; Raymond Reiser

1965-01-01

40

Solvation parameters. Part 5: physicochemical interpretation of experimental solvent values for stationary phases of gas-liquid chromatography.  

PubMed

It has been demonstrated for a long time that in the particular case of gas-liquid chromatography (GLC), a linear free energy relationship (LFER) of five terms can be established, each term including a parameter of solute and a parameter of solvent. The nature of some of these parameters has been quite clearly identified, even if not always well predicted from the molecular structure. First of all, the five solute parameters: two involved in the hydrogen bonding and three in the Van der Waals forces; secondly, the two solvent parameters involved in hydrogen bonding. It was remaining an uncertainty concerning the nature of the solvent parameters named D, W and E, respectively associated with the solute parameters of dispersion, orientation and induction/polarizability. This uncertainty has been solved using experimental chromatographic data of McReynolds (56 phases) and of the Kováts group (11 phases). The parameter W appears as of polar nature strictly speaking. The parameters D and E can be expressed by two opposite bilinear functions of 1/V (inverse of molecular volume) and PSA/V (ratio of the polar surface area over the molecular volume). These results are in agreement with previous studies limited to alkanes by the Kováts group. PMID:21612782

Laffort, P

2011-07-01

41

Elevated mannose levels detected by gas-liquid chromatography in hydrolysates of serum from rats and humans with candidiasis.  

PubMed Central

We have developed a gas-liquid chromatographic method for identification of mannose in serum hydrolysates by utilizing peracetylated aldononitrile derivatives. Experimentally infected rats and human subjects with candidiasis were studied. Peaks in unknown samples were identified by co-chromatography of reference carbohydrates. Inositol was used as an internal standard. Mannose was identified in hydrolysates of normal rat (391.85 +/- 66.18 micrograms/ml) and human (297.87 +/- 77.81 micrograms/ml) sera. Significantly increased concentrations of mannose (greater than 526.21 micrograms/ml) were demonstrated in hydrolysates of sera from 26 of 36 (72%) experimentally infected rats tested 1 or more days after onset of infection. Significant increases (greater than 453.49 micrograms/ml) were also seen in humans with localized (6/15), transient (2/2), and disseminated (5/7) candidiasis. The concentrations were highest in patients with candidemia occurring either transiently or as part of disseminated infection. The concentrations in patients with localized candidiasis were lower but were still significantly greater than control. These data suggest that changes in mannose concentration, as measured, may serve as markers of candidiasis. The amount of mannose present may be in part a function of the extent of the infection. PMID:7107851

Marier, R L; Milligan, E; Fan, Y D

1982-01-01

42

Use of gas-liquid chromatography as a screening test for toxigenic Clostridium difficile in diarrhoeal stools.  

PubMed

In order to determine if gas-liquid chromatography (GLC) on concentrated stool extracts could be substituted to cell culture assay for cytotoxicity, we prospectively studied 154 diarrhoeal stools submitted for detection of Clostridium difficile toxin. Isocaproic-positive samples were cultured on egg yolk agar supplemented with cycloserine, cefoxitin and fructose for isolation of C difficile, and on egg yolk agar plus kanamycin for isolation of other clostridium species. Of the 154 samples, 129 were GLC-negative (height of the isocaproic peak less than 1.2 cm) and were toxin-negative. Twenty-five stools yielded isocaproic acid; C difficile isolated from 13 of them, six of which were also toxin-positive. Four other isocaproic-positive samples yielded C bifermentans and C sordellii; all were toxin-negative. These results indicate that a negative GLC is an excellent screening test for excluding C difficile infection; positive results must be checked by toxin testing and culture since they are not necessarily associated with the presence of C difficile or its toxin. PMID:6630574

Pepersack, F; Labbe, M; Nonhoff, C; Schoutens, E

1983-11-01

43

Rapid presumptive diagnosis of anaerobic infections in animals by gas-liquid chromatography.  

PubMed

The detection of volatile fatty acids (VFA) by gas chromatography of 85 purulent specimens from abscesses or pyogenic infections in cats, dogs, rodents, and ruminants was compared with the results of bacteriologic culturing, and proved to be a rapid means of presumptively diagnosing anaerobic infections. Of 83 bacteriologically positive specimens, 52 (61%) yielded obligate anaerobes and in 50 specimens, 1 or more VFA (butyric acid, isobutyric acid, valeric acid, isovaleric acid, caproic acid, or isocaproic acid) was detected. Forty-six specimens were positive for culturing of anaerobes and for detection of 1 or more of these VFA. By contrast, pus from infections caused by (facultative) aerobic microorganisms contained no VFA or only acetic and/or propionic acid. PMID:2679251

van den Bogaard, A E; Hazen, M J; Maes, J H

1989-09-01

44

Determination of acrylonitrile in foods by headspace gas-liquid chromatography with nitrogen-phosphorus detection.  

PubMed

A general procedure is described for the determination of acrylonitrile (AN) in foods such as margarine, honey butter, cold-pack cheese, and peanut butter, which are likely to be packaged in AN-based plastic. The entire sample is blended with water and salt at less than 5 degrees C, aliquots are sealed in crimp-top vials, and the vials are equilibrated in a boiling water bath. The headspace is sampled by using a heated syringe, and AN is determined by gas chromatography with a nitrogen-phosphorus selective detector. The inclusion of propionitrile as an internal standard allows quantitation of AN with detection at 4,4, and 10 ppb for margarine, honey butter, and cold-pack cheese, respectively. A peak corresponding to about 5 ppb apparent AN in all non-AN-packaged peanut butter samples examined limits detection in peanut butter to about 15 ppb. The coefficients of variation at 20 ppb for margarine, honey butter, cold-pack cheese, and peanut butter were 7.5, 8.3, 7.3, and 10.2%, respectively. PMID:6630123

Page, B D; Charbonneau, C F

1983-09-01

45

Efficiency of buffered aqueous carboxylic acid solutions and organic solvents to absorb SOâ from industrial flue gas; solubility data from gas-liquid chromatography  

Microsoft Academic Search

Nine adsorbents were examined. These potential candidates for flue gas desulfurization included 1-methyl-2-pyrrolidinone, tri-n-butyl phosphate (TBP), both 0.5 M and 1.0 M solutions of citric acid and glycolic acid, buffered to pH's of 4.5 and 3.8, and pure water. Infinite dilution activity coefficients of SOâ were obtained by gas-liquid chromatography in a trial solvent of Nitrobenzene, and then in systems

Sanza

1982-01-01

46

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

47

Studies of stools from pseudomembranous colitis, rotaviral, and other diarrheal syndromes by frequency-pulsed electron capture gas-liquid chromatography.  

PubMed

Thirty-five patients with various diarrheal syndromes and 22 controls were studied. All stool samples were carefully cultured for Clostridium difficile, using selective isolation media. Cytotoxin assays with proper antitoxin neutralization were done in MRC-5 cells. The stool samples were extracted four times, three times at pH 2 and once at pH 10, using CHCl3 or ether. Derivatizations of extracts were done with trichloroethanol, heptafluorobutyric anhydride, and heptafluorobutyric anhydride-ethanol, and all derivatives were analyzed by frequency-pulsed electron capture gas-liquid chromatography (FPEC-GLC). A dedicated computer was used to assist in both qualitative and quantitative data analysis. Isocaproic acid (iC6) was always found in stool from which C. difficile was isolated and was absent in C. difficile-negative specimens. p-Cresol was found frequently in both persons with pseudomembranous colitis and controls. Tryptamine was found in stool containing C. bifermentans. The FPEC-GLC profiles of persons with acute diarrhea were very different from those of normal persons. Diarrhea associated with adenovirus and rotavirus, Klebsiella spp., and Escherichia spp. showed different FPEC-GLC patterns. Stools from well persons consistently contained full-scale peaks of pyruvic, acetic, propionic, isobutyric, butyric, isovaleric, and valeric acids. In rotavirus stools isobutyric, isovaleric, and valeric acids were reduced in quantity from those found in control stools, whereas propionic and butyric acids were increased. PMID:6490836

Brooks, J B; Nunez-Montiel, O L; Basta, M T; Hierholzer, J C

1984-09-01

48

Detection of metabolites by frequency-pulsed electron capture gas-liquid chromatography in serum and cerebrospinal fluid of a patient with Nocardia infection.  

PubMed Central

Serum (SR) and cerebrospinal fluid (CSF) from a patient suspected of having tuberculous meningitis were submitted to our laboratory for analysis by frequency-pulsed electron capture gas-liquid chromatography (FPEC GLC). The samples were tested for the presence of carboxylic acids, alcohols, hydroxy acids, and amines by methods described previously (C. C. Alley, J. B. Brooks, and D. S. Kellogg, Jr., J. Clin. Microbiol. 9:97-102, 1977; J. B. Brooks, C. C. Alley, and J. A. Liddle, Anal. Chem. 46:1930-1934, 1974; J. B. Brooks, D. S. Kellogg, Jr., M. E. Shepherd, and C. C. Alley, J. Clin. Microbiol. 11:45-51, 1980; J. B. Brooks, D. S. Kellogg, Jr., M. E. Shepherd, and C. C. Alley, J. Clin. Microbiol. 11:52-58, 1980). The results were different from previous FPEC GLC profiles of SR and CSF from patients with known tuberculous meningitis. Both the SR and CSF contained several unidentified compounds that were not previously detected in tuberculous meningitis or any of our other studies of body fluids. Nocardia brasiliensis was later isolated from the patient. Detection of these metabolites by FPEC GLC could prove to be useful for rapid diagnosis of Nocardia disease, and their identification will provide a better understanding of metabolites produced by Nocardia sp. in vivo. PMID:3818936

Brooks, J B; Kasin, J V; Fast, D M; Daneshvar, M I

1987-01-01

49

Gas-liquid chromatography measurements of activity coefficients at infinite dilution of hydrocarbons and alkanols in 1-alkyl-3-methylimidazolium bis(oxalato)borate  

Microsoft Academic Search

The activity coefficients at infinite dilution, ?i? for various solutes: alkanes, cycloalkanes, 1-alkenes, 1-alkynes, benzene, alkylbenzenes, and alcohols in the ionic liquids 1-butyl-3-methylimidazolium bis(oxalato)borate [BMIM][BOB] and 1-hexyl-3-methyl-imidazolium bis(oxalato)borate [HMIM][BOB] have been determined by gas-liquid chromatography at the temperatures ranging from 308 to 348K. The partial molar excess enthalpies at infinite dilution HiE,? of the solutes in the ionic liquids were

Pei-Fang Yan; Miao Yang; Chang-Ping Li; Xiu-Mei Liu; Zhi-Cheng Tan; Urs Welz-Biermann

2010-01-01

50

Characterization of chaotic dynamic behavior in the gas-liquid slug flow using directed weighted complex network analysis  

NASA Astrophysics Data System (ADS)

Understanding the nonlinear and complex dynamics underlying the gas-liquid slug flow is a significant but challenging problem. We systematically carried out gas-liquid two-phase flow experiments for measuring the time series of flow signals, which is studied in terms of the mapping from time series to complex networks. In particular, we construct directed weighted complex networks (DWCN) from time series and then associate different aspects of chaotic dynamics with the topological indices of the DWCN and further demonstrate that the DWCN can be exploited to detect unstable periodic orbits of low periods. Examples using time series from classical chaotic systems are provided to demonstrate the effectiveness of our approach. We construct and analyze numbers of DWCNs for different gas-liquid flow patterns and find that our approach can quantitatively distinguish different experimental gas-liquid flow patterns. Furthermore, the DWCN analysis indicates that slug flow shows obvious chaotic behavior and its unstable periodic orbits reflect the intermittent quasi-periodic oscillation behavior between liquid slug and large gas slug. These interesting and significant findings suggest that the directed weighted complex network can potentially be a powerful tool for uncovering the underlying dynamics leading to the formation of the gas-liquid slug flow.

Gao, Zhong-Ke; Jin, Ning-De

2012-05-01

51

Measurement of gas-liquid partition coefficient and headspace concentration profiles of perfume materials by solid-phase microextraction and capillary gas chromatography-mass spectrometry  

PubMed

An empirical model describing the relationship between the partition coefficients (K) of perfume materials in the solid-phase microextraction (SPME) fiber stationary phase and the Linearly Temperature Programmed Retention Index (LTPRI) is obtained. This is established using a mixture of eleven selected fragrance materials spiked in mineral oil at different concentration levels to simulate liquid laundry detergent matrices. Headspace concentrations of the materials are measured using both static headspace and SPME-gas chromatography analysis. The empirical model is tested by measuring the K values for fourteen perfume materials experimentally. Three of the calculated K values are within 2-19% of the measured K value, and the other eleven calculated K values are within 22-59%. This range of deviation is understandable because a diverse mixture was used to cover most chemical functionalities in order to make the model generally applicable. Better prediction accuracy is expected when a model is established using a specific category of compounds, such as hydrocarbons or aromatics. The use of this method to estimate distribution constants of fragrance materials in liquid matrices is demonstrated. The headspace SPME using the established relationship between the gas-liquid partition coefficient and the LTPRI is applied to measure the headspace concentration of fragrances. It is demonstrated that this approach can be used to monitor the headspace perfume profiles over consumer laundry and cleaning products. This method can provide high sample throughput, reproducibility, simplicity, and accuracy for many applications for screening major fragrance materials over consumer products. The approach demonstrated here can be used to translate headspace SPME results into true static headspace concentration profiles. This translation is critical for obtaining the gas-phase composition by correcting for the inherent differential partitioning of analytes into the fiber stationary phase. PMID:11011720

Liu; Wene

2000-09-01

52

Frequency-pulsed electron capture gas-liquid chromatographic analysis of metabolites produced by Clostridium difficile in broth enriched with amino acids.  

PubMed

Clostridium difficile strain CDC A-567 was cultured in Trypticase (BBL Microbiology Systems)-yeast-salt broth supplemented with 0.2% L-leucine, L-norleucine, L-isoleucine, L-tyrosine, or L-tryptophan. Four extractions were done on the spent medium, three at pH 2 and one at pH 10, using CHCL3 or ether. Derivatizations were done with trichloroethanol, heptafluorobutyric anhydride, and heptafluorobutyric anhydride-ethanol. All samples were analyzed with frequency-pulsed electron capture gas-liquid chromatography. A dedicated computer was used to assist in data analysis. C. difficile produced both short-chain and aromatic acids in Trypticase-yeast-salt broth; hydroxy acids were also detected. p-Cresol, indoleacetic acid, 4-methylthio-2-hydroxybutyric acid, and some unidentified alcohols were observed. The basic chloroform extraction contained cadaverine and putrescine. Leucine, norleucine, and isoleucine influenced the production of C5 and C6 acids and alcohols. L-Tyrosine underwent successive degradation to produce p-cresol and aromatic acids as final products. Tryptophan increased the production of indoleacetic, indolepropionic, and indolebutyric acids. Isocaproic acid was produced in relatively high concentrations regardless of medium substitution. The consistent production of iC6 under various substrate conditions indicates that the production of this compound might be consistent enough in vitro to form the basis of a rapid test for detection of C. difficile in stool specimens by frequency-pulsed electron capture gas-liquid chromatography. PMID:6490835

Brooks, J B; Nunez-Montiel, O L; Wycoff, B J; Moss, C W

1984-09-01

53

Activity coefficients at infinite dilution of organic solutes in the ionic liquid 1-butyl-3-methylimidazolium hexafluoroantimonate using gas–liquid chromatography at T = (313.15, 323.15, and 333.15) K  

Microsoft Academic Search

Activity coefficients at infinite dilution were determined for 27 solutes: n-alkanes, alk-1-enes, alk-1-ynes, cycloalkanes, alkylbenzenes, alcohols, and ketones in the ionic liquid 1-butyl-3-methylimidazolium hexafluoroantimonate, [BMIM][SbF6], by gas–liquid chromatography at three different temperatures, T=(313.15, 323.15, and 333.15)K. The results are compared to published data on related compounds. The partial molar excess enthalpy values at infinite dilution were calculated from the experimental

Eugene Olivier; Trevor M. Letcher; Paramespri Naidoo; Deresh Ramjugernath

2011-01-01

54

Lagrangian coherent structures analysis of gas-liquid flow in a bubble column  

NASA Astrophysics Data System (ADS)

The objective of this paper is to apply a new identifying method to investigating the gas-liquid two-phase flow behaviors in a bubble column with air injected into water. In the numerical simulations, the standard k-? turbulence model is employed to describe the turbulence phenomenon occurring in the continuous fluid. The Finite-Time Lyapunov Exponent (FTLE) and Lagrangian Coherent Structures (LCS) are applied to analyze the vortex structures in multiphase flow. Reasonable agreements are obtained between the numerical and experimental data. The numerical results show that the evolution of gas-liquid in the column includes initial and periodical developing stages. During the initial stage, the bubble hose is forming and extending along the vertical direction with the vortex structures formed symmetrically. During the periodical developing stage, the bubble hose starts to oscillate periodically, and the vortexes move along the bubble hose to the bottom of column alternately. Compared to the Euler-system-based identification criterion of a vortex, the FTLE field presents the boundary of a vortex without any threshold defined and the LCS represents the divergence extent of infinite neighboring particles. During the initial stage, the interfaces between the forward and backward flows are highlighted by the LCS. As for the periodical developing stage, the LCS curls near the vortex centers, providing a method of analyzing a flow field from a dynamical system perspective.

Wu, Qin; Wang, GuoYu; Huang, Biao; Bai, ZeYu

2014-04-01

55

On-line introduction of high-pressure gas-liquid sample for capillary gas chromatographic analysis.  

PubMed

An on-line sample introduction technique in capillary gas chromatograph (CGC) for the analysis of high-pressure gas-liquid mixtures has been designed and evaluated. A sample loop of 0.05 microL and a washing solvent loop of 0.5 microL are mounted on a 10-port switching valve, which serves as the injection valve. A capillary resistor was connected to the vent of sample loop in order to maintain the pressure of the sample. Both the sample and the washing solvent are transferred into the split-injection port through a narrow bore fused silica capillary inserted into the injection liner through a septum. The volume of the liner is used both as the pressure-release damper and evaporation chamber of the sample. On-line analysis of both reactants and resultants in ethylene olimer reaction mixture at 5 MPa was carried out, which demonstrated the applicability of the technique. PMID:15378875

Zhao, Jinghong; Wang, Hanwen; Guan, Yafeng

2004-08-01

56

Routine direct injection gas--liquid chromatographic procedure for the analysis of volatile halogenated anaesthetics in whole blood using a new external injection port.  

PubMed

This communication describes the design and construction of a new external injection port for the direct gas--liquid chromatographic analysis of volatile compounds in whole blood. Aliquots (4--40 microliter) of EDTA anti-coagulated blood containing the volatile compound and a weighed quantity of the internal standard, isobutanol, were injected into the disposable glass wool filter of the carrier gas stream directly onto the chromatographic column. Typical data are presented from chromatography performed with dual 6 ft. x 2 mm I.D. glass columns containing Chromosorb 101 programmed from 110--180 degrees at 6 degrees/min and the external injection port maintained at 180 degrees. The method eliminated the problems usually associated with direct injection methods and permitted the accurate analysis of halothane, methoxyflurane, diethyl ether and ethanol over the approximate range 1--100 mg%. Using this analytical procedure the distribution of halothane between the cells and plasma of human blood at 4 degrees was found to be 2.0 +/- 0.2. PMID:701427

Reid, P E; Brooks, D E; Pang, Y C; Muelchen, R

1978-09-01

57

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

58

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

59

In vitro oxidation of IV lipid emulsions in different all-in-one admixture bags assessed by an iodometric assay and gas-liquid chromatography  

Microsoft Academic Search

Polyunsaturated fatty acids (FAs) of intravenous (IV) lipid emulsions can peroxidize to potentially harmful lipid hydroperoxides. In order to assess in vitro peroxidation of IV fat emulsions in all-in-one (AIO) admixture bags, an iodometric titration to determine lipid hydroperoxide content expressed by the peroxide value (PV) and a gas-liquid chromatographic (GLC) assay to determine changes of the FA pattern were

Patrick J. K. Steger; Stefan F. Mühlebach

1997-01-01

60

Gas/Liquid and Liquid/Liquid Solvent Extraction in Flow Analysis with the Chromatomembrane Cell  

PubMed Central

Since twelve years the Chromatomembrane Cell has been proposed as a new and versatile device for extraxtion procedures in the flow based analysis. In the meantime a remarkable number of papers was submitted dealing with applications of the novel method to all the conceivable varieties of flow injection and sequential injection analysis. The device supports important analytical procedures such as sampling, sample preparation, and preconcentration each being combined with a phase transfer of the analyte. The Chromatomembrane Cell can be coupled to most of the modern detectors which work computer aided in the laboratories of today. Centrepiece of the cell is a block made from biporous hydrophobic PTFE, inside which polar (in the macropores) and nonpolar (in the micropores) solvents come into a close contact with each other and might flow independently with different flow rates. Microporous PTFE membranes prevent polar phases from their flowthrough into directions which are reserved for nonpolar fluids only. Thus, a strict control over the fluxes can be established at the analysts request. Especially, that PTFE block offers outstanding possibilities as a sampling unit for air monitoring.

Moskvin, Leonid N.; Simon, Juergen

2006-01-01

61

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

62

Analysis of mass transfer in the precipitation process of calcium carbonate using a gas\\/liquid reaction  

Microsoft Academic Search

Nowadays a typical method to produce calcium carbonate is based on the gas–liquid reaction between carbon dioxide and aqueous solutions of calcium hydroxide. Several chemical engineering processes are involved in this operation, such as mass transfer, chemical kinetics, etc. The aim of this research work is to study the global reaction process that involves absorption, reaction and precipitation processes. The

Diego Gómez-Díaz; José M. Navaza; Begoña Sanjurjo

2006-01-01

63

In vitro oxidation of i.v. lipid emulsions in different all-in-one admixture bags assessed by an iodometric assay and gas-liquid chromatography.  

PubMed

Polyunsaturated fatty acids (FAs) of intravenous (IV) lipid emulsions can peroxidize to potentially harmful lipid hydroperoxides. In order to assess in vitro peroxidation of IV fat emulsions in all-in-one (AIO) admixture bags, an iodometric titration to determine lipid hydroperoxide content expressed by the peroxide value (PV) and a gas-liquid chromatographic (GLC) assay to determine changes of the FA pattern were established. A long-chain triglyceride (LCT) and medium-chain triglyceride-LCT emulsion were compared for the PV and the pH during storage at room temperature and daylight in AIO bags made of ethylvinylacetate (EVA) and polypropylene:polyamide 7:3 (V90). In contrast to storage in glass bottles, significant peroxidation was detected in both emulsions with 0.5-3.4 mmol peroxides/L after 28 d (150 times the control PV). A pH drop of at least 0.3 (EVA) and 1.2 (V90) units was measured. Initial PVs and peroxidation kinetics of the emulsions were different; V90 material showed better barrier properties against oxygen. PV was increased by higher temperature and light exposure. The FA pattern of an LCT emulsion with a PV > 6 (storage: 40 degrees C in a dark room for 28 d in AIO bags) assayed by GLC remained unchanged. The iodometric peroxide and the GLC assay were reproducible and easy to handle. Only the iodometric method was sensitive enough to detect peroxidation effects (detection limit: 0.02 mmol peroxides/L). IV fat emulsions can be checked for lipid hydroperoxide content with the rapid iodometric assay to guarantee optimal quality of IV lipids used for AIO admixtures. To prevent peroxidation, lipids in AIO bags should be stored light-protected in a refrigerator an oxygen-tight overwrap is mandatory for extended periods. PMID:9106791

Steger, P J; Mühlebach, S F

1997-02-01

64

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

65

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

66

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

67

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

68

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

69

Advances in gas-liquid flows 1990  

SciTech Connect

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 bath, dripping faucet, boiling tea pot, and bubbling beer provide daily experience of gas-liquid flows. The papers presented in this volume reflect the variety and richness of gas-liquid two-phase flow and the increasing role it plays in modern technology. This volume contains papers dealing with some recent development in gas-liquid flow science and technology, covering basic gas-liquid flows, measurements and instrumentation, cavitation and flashing flows, countercurrent flow and flooding, flow in various components and geometries liquid metals and thermocapillary effects, heat transfer, nonlinear phenomena, instability, and other special and general topics related to gas-liquid flows.

Kim, J.M. (Texas Univ., Austin, TX (United States). Nuclear Reactor Lab.); Rohatgi, U.S. (Brookhaven National Lab., Upton, NY (United States)); Hashemi, A. (Lockheed Missiles and Space Company (US))

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

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.

2011-05-16

72

Waves and instabilities in inclined gas-liquid pipe flow  

SciTech Connect

The Modified Apparent Rough Surface (MARS) model successfully predicts liquid holdup and pressure gradient for wavy gas-liquid pipe flow in slightly inclined pipes, up to the transition to slug (intermittent) flow. Additional equations are used to predict the transition from wavy-to-intermittent flow and for the velocity of waves on the gas-liquid interface. In this paper, Linear (stability) Theory is compared with the MARS model, on the basis of measurements in horizontal and slightly inclined (0{degree} {le} {beta} 6{degree}) pipes. Viscous terms in the linear analysis require estimates of shear stresses. Using the MARS model for the interfacial and liquid-to-wall friction factors, stability can be predicted to within reasonable degree of accuracy. Credible wave velocities are also obtained, provided the interfacial waves are not assumed to be marginally stable. Earlier semi-theoretical equations (MARS model) still provide better estimates of both stability and wave velocity and are much easier to handle than Linear Theory. However, the use of good friction factor equations, i.e. those capable of predicting liquid holdup and pressure gradient, has significantly improved the results obtained with Linear Theory. This opens the way to further studies into the mechanisms determining the velocity, growth and instability of waves in gas-liquid pipe flow.

Grolman, E. [Delft Univ. of Technology (Netherlands). Faculty of Chemical Technology and Material Science; Fortuin, J.M.H. [Univ. of Amsterdam (Netherlands). Dept. of Chemical Engineering

1996-12-31

73

Recycle spray gas-liquid contactor  

Microsoft Academic Search

This patent describes an apparatus for effecting gas-liquid mass transfer. It comprises a vertically oriented gas-tight vessel having at the base thereof means for passage of a gas into the vessel and at its top means for passage of a gas therefrom, at least one horizontal tray contained therein, a vertical housing resting on each the tray, an array contained

1991-01-01

74

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

2012-07-10

75

New polypyrrole-carbon nanotubes-silicon dioxide solid-phase microextraction fiber for the preconcentration and determination of benzene, toluene, ethylbenzene, and o-xylene using gas liquid chromatography.  

PubMed

For the first time, a polypyrrole-carbon nanotubes-silicon dioxide composite film coated on a steel wire was prepared by an electrochemical method. Scanning electron microscopy images showed that this composite film was even and porous. The prepared fiber was used as an absorbent for the headspace solid-phase microextraction of benzene, toluene, ethylbenzene, and o-xylene, followed by gas chromatographic analysis. This method presented an excellent performance, which was much better than that of a polypyrrole-carbon nanotube fiber. It was found that under the optimized conditions, the linear ranges were 0.01-200 ng/mL with correlation coefficients >0.9953, the detection limits were 0.005-0.020 ng/mL, the relative standard deviations were 3.9-6.4% for five successive measurements with a single fiber, and the reproducibility was 5.5-8.5% (n = 3). Finally, the developed method was successfully applied to real water samples, and the relative recoveries obtained for the spiked water samples were from 91.0 to 106.7%. PMID:24995551

Sarafraz-Yazdi, Ali; Rounaghi, Gholamhossein; Razavipanah, Iman; Vatani, Hossein; Amiri, Amirhassan

2014-09-01

76

Thin Layer Chromatography for the Analysis of Glycosaminoglycan Oligosaccharides  

PubMed Central

Thin layer chromatography was used to analyze glycosaminoglycan oligosaccharides obtained through the use of polysaccharide lyases. This method allows for the rapid, semi-quantitative analysis of a wide variety of glycosaminoglycan oligosaccharides. PMID:17679101

Zhang, Zhenqing; Xie, Jin; Zhang, Fuming; Linhardt, Robert J.

2007-01-01

77

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...

78

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.

Boston, Wgbh

2002-01-01

79

Analysis of cephalosporins by hydrophilic interaction chromatography  

Microsoft Academic Search

A simple hydrophilic interaction chromatography (HILIC) method was developed to analyze seven cephalosporins. These seven cephalosporins could be separated well on the Click ?-CD column and Atlantis HILIC Silica column. The effects of buffer concentration and pH on the retention under HILIC mode were studied. Except cefepime hydrochloride (4), the retention of other six cephalosporins increased with increasing buffer concentration,

Qiaoxia Liu; Lingyan Xu; Yanxiong Ke; Yu Jin; Feifang Zhang; Xinmiao Liang

80

Analysis of cephalosporins by hydrophilic interaction chromatography.  

PubMed

A simple hydrophilic interaction chromatography (HILIC) method was developed to analyze seven cephalosporins. These seven cephalosporins could be separated well on the Click ?-CD column and Atlantis HILIC Silica column. The effects of buffer concentration and pH on the retention under HILIC mode were studied. Except cefepime hydrochloride (4), the retention of other six cephalosporins increased with increasing buffer concentration, while decreased with increasing pH. Different separation selectivities could be observed on the Click ?-CD column and Atlantis HILIC Silica column, and changing pH also resulted in the changing of separation selectivity. The separations of cephalosporins by HILIC and reversed-phase high performance liquid chromatography (RP-HPLC) were compared, and the two separation modes had good orthogonality. In addition, cefotaxime sodium (1) and its degradation were separated well on the Click ?-CD column, which indicated that the Click ?-CD column by HILIC can be used for studying the stability of cephalosporins. PMID:21035295

Liu, Qiaoxia; Xu, Lingyan; Ke, Yanxiong; Jin, Yu; Zhang, Feifang; Liang, Xinmiao

2011-02-20

81

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.

2011-11-29

82

Protein recovery using gas-liquid dispersions.  

PubMed

Two separation techniques, foam separation and colloidal gas aphrons (CGAs), both of which are based on gas-liquid dispersions, are compared as potential applications for protein recovery in downstream processing. The potential advantages of each method are described and the concentration and selectivity achieved with each method, for a range of proteins is discussed. The physical basis of foam separation is the preferential adsorption of surface active species at a gas-liquid interface, with surface inactive species remaining in bulk solution. When a solution containing surface active species is sparged with gas, a foam is produced at the surface: this foam can be collected, and upon collapse contains surface active species in a concentrated form. CGAs are microbubble dispersions (bubble diameters 10-100 microm) with high gas hold ups (>50%) and relatively high stability, which are formed by stirring a surfactant solution at speeds above a critical value (typically around 5000 rpm). It is expected that when proteins are brought into contact with aphrons, protein adsorbs to the surfactant through electrostatic and/or hydrophobic forces. The aphron phase can be separated easily from the bulk solution due to its buoyancy, thus allowing separation of protein in a concentrated form. PMID:9699972

Noble, M; Brown, A; Jauregi, P; Kaul, A; Varley, J

1998-06-26

83

Supersonic gas-liquid cleaning system  

NASA Technical Reports Server (NTRS)

A system to perform cleaning and cleanliness verification is being developed to replace solvent flush methods using CFC 113 for fluid system components. The system is designed for two purposes: internal and external cleaning and verification. External cleaning is performed with the nozzle mounted at the end of a wand similar to a conventional pressure washer. Internal cleaning is performed with a variety of fixtures designed for specific applications. Internal cleaning includes tubes, pipes, flex hoses, and active fluid components such as valves and regulators. The system uses gas-liquid supersonic nozzles to generate high impingement velocities at the surface of the object to be cleaned. Compressed air or any inert gas may be used to provide the conveying medium for the liquid. The converging-diverging nozzles accelerate the gas-liquid mixture to supersonic velocities. The liquid being accelerated may be any solvent including water. This system may be used commercially to replace CFC and other solvent cleaning methods widely used to remove dust, dirt, flux, and lubricants. In addition, cleanliness verification can be performed without the solvents which are typically involved. This paper will present the technical details of the system, the results achieved during testing at KSC, and future applications for this system.

Caimi, Raoul E. B.; Thaxton, Eric A.

1994-01-01

84

Heat transfer between gas-liquid spray stream flowing perpendicularly to the row of the cylinders  

Microsoft Academic Search

Experimental investigation and analysis of heat transfer process between a gas-liquid spray flow and the row of smooth cylinders placed in the surface perpendicular to the flow has been performed. Among others, there was taken into account in the analysis the phenomenon of droplets bouncing and omitting the cylinder as well as the phenomenon of the evaporation process from the

M. Pawlowski; B. Siwon

1988-01-01

85

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.

2008-08-14

86

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.

House, The S.

2014-01-28

87

Analysis and quantification of plant membrane lipids by thin-layer chromatography and gas chromatography.  

PubMed

Galactolipids represent the predominant membrane lipid class in plants. In general, galactolipids are restricted to plastids, but during phosphate deficiency, they also accumulate in extraplastidial membranes. Two groups of plants can be distinguished based on the presence of a specific fatty acid, hexadecatrienoic acid (16:3), in chloroplast lipids. Plants that contain galactolipids with 16:3 acids are designated "16:3-plants"; the other group of plants which lack 16:3 contain mostly 18:3 in their galactolipids ("18:3-plants"). The methods in this chapter describe the extraction of membrane lipids from whole leaves, or from subcellular fractions, and their analysis via thin-layer chromatography (TLC) with different staining methods. Furthermore, a protocol for membrane lipid quantification is presented starting with the separation via TLC, transmethylation of the isolated lipids to fatty acid methyl esters, and their quantitative analysis via gas chromatography (GC). PMID:23681525

Wewer, Vera; Dörmann, Peter; Hölzl, Georg

2013-01-01

88

Wave processes in a gas-liquid stream  

Microsoft Academic Search

Experimental data are presented on the wave characteristics of the interphase boundary in separated gas-liquid wave flow. An estimate is given of the influence of the waves on the magnitude of the head loss by the friction of the gas-liquid mixture in a horizontal tube.

G. P. Isupov; V. A. Mamaev

1969-01-01

89

GAS\\/LIQUID MEMBRANES FOR NATURAL GAS UPGRADING  

Microsoft Academic Search

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

Howard S. Meyer

2003-01-01

90

Hydrodynamic parameters for gas-liquid cocurrent flow in packed beds  

Microsoft Academic Search

The hydrodynamics of cocurrent gas-liquid flow in packed beds is analyzed by extending the concept of relative permeability to the inertial regime. The relative permeabilities of the gas and liquid phases are functions of the saturation of the liquid phase. These functions are found from an analysis of experimental data. The relations obtained are used to develop empirical correlations for

A. E. Saez; R. G. Carbonell

1985-01-01

91

Micellar electrokinetic capillary chromatography analysis of water-soluble vitamins  

Microsoft Academic Search

This paper describes the development of an electrophoretic method used to analyse seven water-soluble vitamins, and its use in the analysis of pharmaceutical formulations. Thiamine, nicotinamide, nicotinic acid, pyridoxine, ascorbic acid, folic acid and riboflavin were separated from one another in 7min by micellar electrokinetic capillary chromatography using a carrier containing sodium dodecyl sulphate as surfactant, and were subsequently detected

Domingo Blanco Gomis; Luis Laviana González; Dolores Gutiérrez Álvarez

1999-01-01

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

Quantitative analysis of marine oils by capillary supercritical fluid chromatography  

Microsoft Academic Search

Supercritical fluid chromatographic analysis methods have been employed in the examination of several marine oils for the group separation of free fatty acids, retinol, ergocalciferol, cholecalciferol, squalene, tocopherols, cholesterol, was esters, diacylglycerols, cholesteryl esters, and triacylglycerols. The oils were derived from characteristic species including shark, seal, edible and trash fish. The supercritical fluid chromatography (SFC) method used for the separation

A. Staby; C. Borch-Jensen; S. Balchen; J. Mollerup

1994-01-01

94

Comparison of Rapid Methods for Analysis of Bacterial Fatty Acids  

PubMed Central

When rapid gas-liquid chromatography methods for determination of bacterial fatty acids were compared, results showed that saponification was required for total fatty acid analysis. Transesterification with boron-trihalide reagents (BF3-CH3OH, BCl3-CH3OH) caused extensive degradation of cyclopropane acids and was less effective than saponification in releasing cellular hydroxy fatty acids. Digestion of cells with tetramethylammonium hydroxide was unsatisfactory because of extraneous gas-liquid chromatography peaks and because of lower recovery of branched-chain and hydroxy fatty acids. A simple, rapid saponification procedure which can be used for total cellular fatty acid analysis of freshly grown cells is described. PMID:4844271

Moss, C. Wayne; Lambert, M. A.; Merwin, W. H.

1974-01-01

95

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

96

Gas-Liquid Slug Flow in Microchannels  

NASA Astrophysics Data System (ADS)

Slug flow is not only an attractive regime for conducting gas-liquid reactions in microchemical systems. It also provides a normal velocity that enhances liquid mixing for high Peclet number flows, e.g. for particle synthesis. We previously extended the flow regime diagrams initially obtained for micro heat-exchangers to the liquid deficient conditions relevant to microreactors. We use silicon-based single microchannels with rectangular and triangular cross-section and hydraulic diameters of 40-400 microns that are capped with Pyrex to provide for optical access. Ethanol, water, toluene, and nitrogen are the working fluids. Superficial velocities are varied between 0.01 and 10 m/s for the gas and 0.001 and 1 m/s for the liquid with corresponding Capillary and Bond numbers between 0.001 and 0.01. We complement pulsed-laser fluorescence microscopy and confocal scanning microscopy with a non-intrusive optical sensor to monitor the transient flow at sampling rates of 10 kHz. Interfacial area, void fraction, slug velocity U_s, and the transversal velocity component introduced by internal circulation in the liquid are determined. For comparable Peclet numbers, the transverse velocity between channel wall and center is lO0.1 U_s and allows for shorter mixing lengths than reported for micromixers with patterned walls. Gas and liquid are completely separated on-chip subsequent to the mixing step.

Guenther, Axel; de Mas, Nuria; Jhunjhunwala, Manish; Schmidt, Martin A.; Jensen, Klavs F.

2003-11-01

97

Gas-liquid chromatographic determination of 3-trifluoromethyl-4-nitrophenol residues in fish  

USGS Publications Warehouse

A procedure for the determination of 3-mftuormethyl-4-nitrophenol (TFM) in fish tissues is described. Homogenized tissues are extracted with hexane-ethyl ether; the extract is cleaned up by partitioning the TFM from the extracting solvent into O.IN NaOB, acidifying the aqueous solution, and partitioning again with hexaneethyl ether. The TFM is methylated with diazomethane and analyzed by gas-liquid chromatography, using electron capture detection. Recoveries ranged from 75 to 1000/., from fish muscles that were spiked with 0.01-2.00 JA#g TFM/g.

Allen, J.L.; Sills, J.B.

1974-01-01

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

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

100

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.

101

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

102

Using Single Drop Microextraction for Headspace Analysis with Gas Chromatography  

NASA Astrophysics Data System (ADS)

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 for instructional use, especially to illustrate HS analysis or as an alternative to solid-phase microextraction (SPME) to which it is very similar. The basic principles and practice of HS-GC using SDME are described, including a complete review of the literature. Some possible experiments are suggested using water and N -methylpyrrolidone (NMP) as solvents.

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

2008-07-01

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

Hydrodynamics and interfacial gas-liquid mass transfer of gas-liquid-solid fluidized beds  

SciTech Connect

Hydrodynamic characteristics of a cocurrent, gas-liquid-solid fluidized bed is studied to simulate the resid hydrotreating reaction conditions using an aqueous surfactant solution. Reaction conditions for hydrotreating of residual oils and coal liquefaction, which uses cylindrical hydrotreating catalysts under conditions of high gas holdup, are simulated using an aqueous t-pentanol (0.5 wt%) solution as the liquid phase. A mathematical model is developed to described the minimum fluidization velocity behavior. Bed voidage, gas holdup and terminal velocity of the particles are analyzed and correlated empirically to investigate the effect of particle shape and liquid surface tension. Systematic effects of particle properties on bubble wake structure as well as bubble rise characteristics for a single rising bubble in a liquid-solid fluidized bed are studied visually. In order to determine the solids holdup in near wake behind a single bubble, an image processing technique is employed. The bubble rise velocity, the volume ratio of primary wake to bubble, the volume ratio of liquid wake to bubble, and the wake solid holdup are strongly dependent on the particle terminal velocity and the bed expansion. A spectrophotometric technique is developed for the measurement of the instantaneous mass transfer coefficient and the interfacial areas of a bubble as well as the local concentration distribution around the bubble-wake. An ozone and starch-potassium iodide reaction is employed to visualize the gas-liquid mass transfer to a single bubble in liquids and liquid-solid fluidized beds. Axial variations of the concentration, bubble volume and the mass transfer rate are studied. The mass transfer coefficient is found to be dependent on bubble size and bed expansion.

Song, Gyung-Ho.

1989-01-01

105

Group type analysis of asphalt by column liquid chromatography  

SciTech Connect

An improved analysis method for characterization of asphalt was established. The method is based on column chromatography technique. The asphalts were separated into four groups: saturates, aromatics, resins, and asphaltenes, quantitatively. About 0.1 g of sample was required in each analysis. About 20 mL of n-heptanes was used to separate out saturates first. Then about 35 mL of n-heptanes/dichloromethane (.5, v/v) mixture was used to separate out aromatics. About 30 mL of dichloromethane/tetrahydrofuran (1/3, v/v) mixture was used to separate out resin. The quality of the separation was confirmed by infrared spectra (IR) and {sup 1}H NMR analysis. The model compounds, tetracosan for saturates, dibenz(o)anthracen for aromatics, and acetanilide for resins were used for verification. The IR and {sup 1}H NMR analysis of the prepared fractions from the column liquid chromatography were in good agreement that of pure reagents.

Zhang, C.; Yang, J.; Xue, Y.; Li, Y. [Chinese Academy of Science, Taiyuan (China)

2008-07-01

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

Reliable Peak Selection for Multisample Analysis with Comprehensive Two-Dimensional Chromatography  

E-print Network

Reliable Peak Selection for Multisample Analysis with Comprehensive Two-Dimensional Chromatography with samples of complex bio-oils analyzed by comprehensive two-dimensional gas chromatography (GCxGC) coupled-dimensional gas chromatography (GCxGC) and comprehensive two-dimensional liquid chroma- tography (LCxLC), hold

Reichenbach, Stephen E.

108

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 analysis using high-performance liquid chromatography­mass spectrometry Rienk H. Smittenberg, Julian P September 2007 Abstract A semi-preparative normal-phase high-performance liquid chromatography

Gilli, Adrian

109

Discussion of jump condition at gas-liquid interface  

NASA Astrophysics Data System (ADS)

A modeling of gas-liquid interface is one of key issues of the numerical research on multiphase flow. Currently, the Continuum Surface Force model (CSF: Brackbill et al., 1992) is popular to model a gas-liquid interface in computational fluid dynamics. However, the CSF model cannot explain the physics of the gas-liquid interface because this model is derived by a mechanical energy balance at the interface. As a practical matter, we must consider the physics of bubble coalescence or breakup, soap bubble and so on. In this study, assuming that the interface is a thin membrane and has a finite thickness, we develop a new mathematical model of the gas-liquid interface based on thermodynamics and mathematical approach. In particular, we derive the equation of free energy based on Lattice gas model including both influences of the electric double layer caused by a contamination and the jump condition at gas-liquid interface treated by thermodynamics. Finally, we compare this thermodynamic jump condition with the conventional one.

Yonemoto, Yukihiro; Kunugi, Tomoaki

2006-11-01

110

Phase diagram and universality of the Lennard-Jones gas-liquid system  

NASA Astrophysics Data System (ADS)

The gas-liquid phase transition of the three-dimensional Lennard-Jones particles system is studied by molecular dynamics simulations. The gas and liquid densities in the coexisting state are determined with high accuracy. The critical point is determined by the block density analysis of the Binder parameter with the aid of the law of rectilinear diameter. From the critical behavior of the gas-liquid coexisting density, the critical exponent of the order parameter is estimated to be ? = 0.3285(7). Surface tension is estimated from interface broadening behavior due to capillary waves. From the critical behavior of the surface tension, the critical exponent of the correlation length is estimated to be ? = 0.63(4). The obtained values of ? and ? are consistent with those of the Ising universality class.

Watanabe, Hiroshi; Ito, Nobuyasu; Hu, Chin-Kun

2012-05-01

111

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

112

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

113

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

114

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

115

SIMULATION OF AEROSOL FORMATION IN GAS-LIQUID CONTACT DEVICES  

Microsoft Academic Search

In gas-liquid contact devices like absorbers, quench coolers, or condensers, aerosols can be formed by spontaneous phase transitions, initiated by homogeneous or heterogeneous nucleation, if a supersaturated gas phase emerges due to simultaneous heat and mass transfer processes or chemical reactions. Typical examples are the absorption of acid gases, like HCl or SO3, the condensation of solvents in the presence

A. Wix; K. Schaber; O. Ofenloch; R. Ehrig; P. Deuflhard

2007-01-01

116

Chemical analysis of outgassing contaminants on spacecraft surfaces  

NASA Technical Reports Server (NTRS)

Methods for analyzing and characterizing outgassing contaminants from such materials as RTV 501 potting compound and S 13 G paint are presented. Fractional distillation of a gross distillate from RTV 501 rubber was carried out and the distilled fractions examined as to their ultraviolet and infrared spectra by gas liquid chromatography. A sensitive technique for structural analysis and molecular identification was found to consist of a gas chromatography-mass spectroscopy system, which was determined to be economically unfeasible at present.

Mcnutt, R. C.

1973-01-01

117

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

118

The Use of Gas Chromatography for Biogas Analysis  

NASA Astrophysics Data System (ADS)

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

Andersen, Amanda; Seeley, John; Aurandt, Jennifer

2010-04-01

119

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

120

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

121

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

122

Optimum design of space storable gas/liquid coaxial injectors.  

NASA Technical Reports Server (NTRS)

Review of the results of a program of single-element, cold-flow/hot-fire experiments performed for the purpose of establishing design criteria for a high-performance gas/liquid (FLOX/CH4) coaxial injector. The approach and the techniques employed resulted in the direct design of an injector that met or exceeded the performance and chamber compatibility goals of the program without any need for the traditional 'cut-and-try' development methods.

Burick, R. J.

1972-01-01

123

Foams as specific gas-liquid technological media  

Microsoft Academic Search

Basic physicochemical notions of foams as specific gas-liquid technological media are systematized. Structural properties,\\u000a main parameters, and models of foam are considered. The adsorption-kinetic nature of the skeleton structure-forming phase\\u000a of foam is discussed. Particular attention is given to the theoretical description of the internal hydrodynamics of foams,\\u000a the concept of hydroconduction, and the syneresis phenomenon. Basic principles of rheological

D. A. Kazenin; A. V. Vyaz’min; A. D. Polyanin

2000-01-01

124

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 with switching boundary conditions. Our contribution is to show, through the specific example of SMB the specific example of SMB chromatography [16] and to show how exponential stability (in L2-norm) can

Bastin, Georges

125

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 with switching boundary conditions. Our contribution is to show, through the specific example of SMB through the specific example of SMB chromatography [16] and to show how exponential stability (in L2-norm

Bastin, Georges

126

Thin-layer chromatography analysis of fructooligosaccharides in biological samples.  

PubMed

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 and polysaccharide maltodextrin have been added into the feed. Thereby it contributes to a clarification of fructooligosaccharides and polysaccharides transformation in the digestive system. Chromatographic separation has been studied on different chromatographic systems (stationary and mobile phases). Optimal separation of fructooligosaccharides in dietetic products as well as in the samples from intestinal tract of monogastric animals has been achieved on glass-backed precoated silica gel layers impregnated with sodium acetate. The layers were developed with butanol-ethanol-water (5:3:2, v/v) in a vertical trough glass chamber with mobile phase vapour saturation. The visualisation of FOSs on chromatograms was performed with mixture of diphenylamine-aniline-phosphoric acid in acetone as primary detection reagent. Coloured spots of FOSs (blue-pink spots) on chromatograms have also been detected by reflectance densitometry at wavelength lambda=370nm. Simultaneously, the concentration of acetic acid, which is one of FOSs fermentation product, was monitored in the intestinal contents from jejunum, ileum and colon by capillary isotachophoresis. PMID:16455090

Reiffová, Katarína; Nemcová, Radomíra

2006-03-31

127

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

128

Confectionery fat analysis with high performance liquid chromatography  

Microsoft Academic Search

Natural triglyceride mixtures have been analyzed by a variety of techniques. Earlier methods, such as crystallization, were\\u000a unsuitable because they were very time-consuming, required large amounts of material and were not reproducible. Later advances\\u000a in chromatography gave successful separations of triglycerides but required a combination of techniques to give suitable separations.\\u000a High performance liquid chromatography (HPLC) with very efficient columns

R. L. Kimmey; E. G. Perkins

1984-01-01

129

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.

2011-04-13

130

Alkaloids analysis using off-line two-dimensional supercritical fluid chromatography × ultra-high performance liquid chromatography.  

PubMed

In this study, an off-line two-dimensional (2-D) supercritical fluid chromatography (SFC) × ultra-high performance liquid chromatography (UHPLC) method with high orthogonality was developed for the analysis of the practical amide alkaloids fraction from P. longum L. The effects of SFC parameters such as column type, organic modifier, temperature and back-pressure on separation were systematically evaluated. Different selectivity was observed for different columns (BEH, BEH 2-EP, XAmide and CSH FP). An investigation was then carried out of the orthogonality of different columns and systems following a geometric approach with a set of amide alkaloid samples. The orthogonality between a CSH FP column and a BEH column reached 50.79%, which was much higher than that for the other columns. While the orthogonality between SFC and UHPLC based on an XAmide column and an HSS T3 column reached 69.84%, which was the highest of all the combinations. At last, the practical amide alkaloids fraction was analyzed with an off-line 2-D chromatography SFC × UHPLC system. In total, at least 340 peaks were detected by this method. Rapid separation in these two dimensions and easy post treatment of SFC facilitated this 2-D system for the separation of complex samples. PMID:24828698

Li, Kuiyong; Fu, Qing; Xin, Huaxia; Ke, Yanxiong; Jin, Yu; Liang, Xinmiao

2014-07-21

131

Qualitative Analysis of Analgesic Tablets: An Experiment Employing High Pressure Liquid Chromatography.  

ERIC Educational Resources Information Center

Describes an experiment on the qualitative analysis of several over-the-counter analgesic tablets. Background information, procedures used (including high pressure liquid chromatography), and typical student results are included. (JN)

Beaver, Rodney W.; And Others

1983-01-01

132

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...

133

Gas Chromatography/Matrix Isolation-Infrared Spectrometry for Air Sample Analysis.  

National Technical Information Service (NTIS)

The report describes the application of gas chromatography/matrix-isolation 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, indoo...

J. W. Childers

1990-01-01

134

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

135

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

136

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

137

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

138

Comprehensive two-dimensional chromatography in food analysis  

Microsoft Academic Search

Comprehensive two-dimensional (2D) chromatographic techniques can be considered innovative methods, only quite recently developed. Since their introduction to the chromatographic community, these techniques have been used in several fields and have gained an excellent reputation as valuable and powerful analytical tools. The revolutionary aspect of comprehensive multidimensional (MD) techniques, in respect to classical MD chromatography, is that the entire sample

Peter Quinto Tranchida; Paola Dugo; Giovanni Dugo; Luigi Mondello

2004-01-01

139

Analysis of polystyrene and related resins by pyrolysis gas chromatography  

Microsoft Academic Search

Pyrolysis gas chromatography was used for the determination of the monomeric composition of some hydrocarbon resins resulting from the liquid product of naphtha pyrolysis. The effect of working conditions on the peak composition of the pyrogram was investigated. From the monomer peak areas corrected by experimental factors the monomeric composition of a copolymer can be calculated.

P. Fuchs; C. Szepesy

1968-01-01

140

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...

141

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...

142

Micromixing of miscible liquids in segmented gas-liquid flow.  

PubMed

We present an integrated microfluidic system that achieves efficient mixing between two miscible liquid streams by introducing a gas phase, forming a segmented gas-liquid (slug) flow, and completely separating the mixed liquid and gas streams in a planar capillary separator. The recirculation motion associated with segmented flow enhances advection in straight microchannels without requiring additional fabrication steps. Instantaneous velocity fields are quantified by microscopic particle image velocimetry (muPIV). Velocities in the direction normal to the channel amount to approximately 30% of the bulk liquid velocity inside a liquid segment. This value depends only weakly on the length of a liquid segment. Spatial concentration fields and the extent of mixing (EOM) are obtained from pulsed-laser fluorescence microscopy and confocal scanning microscopy measurements. The mixing length is reduced 2-3-fold in comparison with previously reported chaotic micromixers that use three-dimensional microchannel networks or patterned walls. Segmented gas-liquid microflows allow mixing times to be varied over several orders of magnitude between milliseconds and second time scales. PMID:15697306

Günther, Axel; Jhunjhunwala, Manish; Thalmann, Martina; Schmidt, Martin A; Jensen, Klavs F

2005-02-15

143

Deformation of advancing gas-liquid interfaces in capillary tubes.  

PubMed

Deformation of an advancing gas-liquid meniscus is considered in two cases: prewetted and dry capillary tubes. The shape, slope, and curvature of the gas-liquid interface are determined assuming small Weber and Bond numbers, i.e., in the case of negligible inertia and gravity terms. For the prewetted capillary case, the dynamic contact angle rate-dependency is found to depend on both the capillary number and the ratio of the macroscopic prewetting film thickness to the capillary radius. Results are found intermediate between rate-dependency relations available in the literature. In the case of dry capillaries, the relative magnitudes of the viscous, capillary, and disjoining pressure effects are determined. The actual location of the three-phase contact line is analyzed in relation to the spreading coefficient. Results for the dynamic contact angle rate-dependency are found to agree well with published experimental data. In both cases, prewetted and dry capillaries, results are compared with Tanner's relationship and previous theoretical investigations. PMID:12927179

Chebbi, Rachid

2003-09-01

144

Intrusion of fluids into nanogrooves: how geometry determines the shape of the gas-liquid interface.  

PubMed

We study the shape of gas-liquid interfaces forming inside rectangular nanogrooves (i.e., slit-pores capped on one end). On account of purely repulsive fluid-substrate interactions the confining walls are dry (i.e., wet by vapor) and a liquid-vapor interface intrudes into the nanogrooves to a distance determined by the pressure (i.e., chemical potential). By means of Monte Carlo simulations in the grand-canonical ensemble (GCEMC) we obtain the density rho(z) along the midline (x = 0) of the nanogroove for various geometries (i.e., depths D and widths L) of the nanogroove. We analyze the density profiles with the aid of an analytic expression which we obtain through a transfer-matrix treatment of a one-dimensional effective interface Hamiltonian. Besides geometrical parameters such as D and L , the resulting analytic expression depends on temperature T , densities of coexisting gas and liquid phases in the bulk rho g,l(x) and the interfacial tension gamma. The latter three quantities are determined in independent molecular dynamics simulations of planar gas-liquid interfaces. Our results indicate that the analytic formula provides an excellent representation of rho(z) as long as L is sufficiently small. At larger L the meniscus of the intruding liquid flattens. Under these conditions the transfer-matrix analysis is no longer adequate and the agreement between GCEMC data and the analytic treatment is less satisfactory. PMID:18301865

Bohlen, H; Parry, A O; Díaz-Herrera, E; Schoen, M

2008-01-01

145

Forensic Applications of Gas Chromatography-Differential Mobility Spectrometry, Gas Chromatography/Mass Spectrometry, and Ion Mobility Spectrometry with Chemometric Analysis.  

E-print Network

?? Rapid, practical, and low-cost analytical methods are always desirable in forensic analysis. Using proper sample preparation techniques with the application of gas chromatography/mass spectrometry… (more)

Lu, Yao

2010-01-01

146

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

147

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

148

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

149

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... 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...

Barbuceanu, Nicolae

2012-06-07

150

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

151

Affinity chromatography with immobilized DNA stationary phase for biological fingerprinting analysis of traditional Chinese medicines.  

PubMed

A stationary phase for high performance affinity chromatography with immobilization of DNA onto silica gel was prepared and characterized. The effect of the ionic strength, concentration of Mg2+, EDTA and CH3CN in the mobile phase on the retention of alkaloids were investigated. With this stationary phase, biological fingerprinting analysis of traditional Chinese medicines (TCMs) Coptis chinensis Franch and Rheum palmatum L. was performed with both one-dimensional (1-D) and two-dimensional (2-D) chromatography. The 1-D chromatography was performed with isocratic and gradient elution and 2-D chromatography was developed with immobilized DNA column combined with silica monolithic ODS column. It was found that 7 compounds in Coptis chinensis Franch including berberine, palmatine and jatrorrhizine, 14 compounds in Rheum palmatum L. including aloe-emodin, rhein, emodin, chrysophannol-8-O-glucophranoside and physionl-8-O-glucophranoside were active in binding to the immobilized DNA. PMID:17451725

Su, Xingye; Hu, Lianghai; Kong, Liang; Lei, Xiaoyuan; Zou, Hanfa

2007-06-22

152

Isothermal gas-liquid flow at reduced gravity  

NASA Technical Reports Server (NTRS)

Research on adiabatic gas-liquid flows under reduced gravity condition is presented together with experimental data obtained using a NASA-Lewis RC 100-ft drop tower and in a LeRC Learjet. It is found that flow patterns and characteristics remain unchanged after the first 1.5 s into microgravity conditions and that the calculated time for a continuity wave to traverse the test section is less than 1.2 s. It is also found that the dispersed bubbles move at the same velocity as that of the front of the slug and that the transition between bubbly and slug flow is insensitive to diameter. Both the bubbly and the slug flows are suggested to represent a continuum of the same physical process. The characteristics of annular, slug, and bubbly flows are compared.

Dukler, A. E.

1990-01-01

153

Fuel-efficient natural gas-liquid fractionation plant. [Consolidated Storage, Inc. underground storage facility in Hutchinson, Kansas, into which was incorporated a natural gas liquid fractionating plant  

Microsoft Academic Search

Energy-saving measures, which were integrated into an existing natural gas liquids storage facility during the construction and installation of a gas-liquids fractionation plant, are described. The plant, as designed, utilizes closed-loop microprocessor computer control of the fractionation towers, heat-pumping the splitter, a high-efficiency heating oil furnace, and extensive waste reclaiming; it now operates on a routine continuous basis at a

C. Drake; J. Jameyson

1982-01-01

154

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  

Microsoft Academic Search

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

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

2011-01-01

155

Water-only chemical analysis methodologies: investigations of water liquid chromatography, subcritical water extracton, and dynamic surface tension detection.  

E-print Network

??Investigations into methods for performing chemical analysis using a solvent exclusively of water are demonstrated in the areas of liquid chromatography, solid-liquid extraction, and dynamic… (more)

Young, Toby Edward, 1970-

1998-01-01

156

Analysis of Volatile Substances in Samples containing Non-volatile Substances by Process Gas Chromatography  

Microsoft Academic Search

RECENTLY, we experienced difficulties with the automatic analysis by gas chromatography of a process stream consisting of a liquid mixture of organic chemicals. These arose because traces of non-volatile tars and polymers in the sample eventually accumulated in the entrance of the first column of the chromatograph. (This chromatograph normally uses two columns to perform the analysis and has a

C. S. F. Pine

1966-01-01

157

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,*, and Rong Zeng*, Research Center for Proteome Analysis, Key Lab of Proteomics, Institute of Biochemistry proteome has occurred in recent years because it holds great promise of revolution in disease diagnosis

Tian, Weidong

158

Designing nanostructured heterogeneous catalysts to exploit pulsing in gas-liquid packed bed reactors  

E-print Network

in volume of gas-liquid packed bed reactors (a.k.a. "trickle" beds) by an order of magnitude or more because reactor volume. The net effect is that the length of packed bed reactors for gas-liquid reactions could-liquid packed bed reactors for "closet scale" distributed production for chemicals that are hazardous

McCready, Mark J.

159

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

160

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

161

Structural analysis of amorphous phosphates using high performance liquid chromatography  

SciTech Connect

Determining the atomic-scale structure of amorphous solids has proven to be a formidable scientific and technological problem for the past 100 years. The technique of high-performance liquid chromatography (HPLC) provides unique detailed information regarding the structure of partially disordered or amorphous phosphate solids. Applications of the experimental technique of HPLC to phosphate solids are reviewed, and examples of the type of information that can be obtained with HPLC are presented. Inorganic phosphates encompass a large class of important materials whose applications include: catalysts, ion-exchange media, solid electrolytes for batteries, linear and nonlinear optical components, chelating agents, synthetic replacements for bone and teeth, phosphors, detergents, and fertilizers. Phosphate ions also represent a unique link between living systems and the inorganic world.

Sales, B.C.; Boatner, L.A.; Chakoumakos, B.C.; McCallum, J.C.; Ramey, J.O.; Zuhr, R.A.

1993-12-31

162

Asymptotic stability of the compressible gas-liquid model with well-formation interaction and gravity  

NASA Astrophysics Data System (ADS)

In this paper we are concerned with the initial-boundary value problem of the compressible gas-liquid model with well-formation interaction and gravity. The asymptotic behavior of solutions to steady states is established. Also the time-decay rates of perturbed solutions in the sense of L? norm are obtained under some suitable assumptions on the initial date, if ?>1 (associated with pressure law of gas) and ??(0,?/2]?(0,?-??)?(0,?+?/?3] where ? characterizes the viscosity coefficient and ? describes the mass decay rate at the boundary. A main purpose of this work is to clarify the role played by the well-reservoir interaction term. The analysis demonstrates that it is essential to take into account information about sign as well as size of the interaction term in order to obtain time-independent estimates when it operates in combination with gravity.

Evje, Steinar; Liu, Qingqing; Zhu, Changjiang

2014-11-01

163

Analysis of Polyamines in Higher Plants by High Performance Liquid Chromatography 1  

PubMed Central

A sensitive (0.01-1 nmol) method has been developed for the analysis of polyamines in higher plant extracts based on high performance liquid chromatography (HPLC) of their benzoyl derivatives (Redmond, Tseng 1979 J Chromatogr 170: 479-481). Putrescine, cadaverine, agmatine, spermidine, spermine, and the less common polyamines nor-spermidine and homospermidine can be completely resolved by reverse phase HPLC, isocratic elution with methanol:water (64%, v/v) through a 5-?m C18 column, and detection at 254 nm. The method can be directly applied to crude plant extracts, and it is not subject to interference by carbohydrates and phenolics. A good quantitative correlation was found between HPLC analysis of benzoylpolyamines and thin layer chromatography of their dansyl derivatives. With the HPLC method, polyamine titers have been reproducibly estimated for various organs of amaranth, Lemna, oat, pea, Pharbitis, and potato. The analyses correlate well with results of thin layer chromatography determinations. Images PMID:16662279

Flores, Hector E.; Galston, Arthur W.

1982-01-01

164

Determination of partition coefficients from surface acoustic wave vapor sensor responses and correlation with gas-liquid chromatographic partition coefficients  

SciTech Connect

Surface acoustic wave (SAW) devices coated with a thin film of a stationary phase sense chemical vapors in the gas phase by detecting the mass of the vapor that distributes into the stationary phase. This distribution can be described by the partition coefficient. An equation is presented that allows partition coefficients to be calculated from SAW vapor sensor frequency shifts. The experimental responses of fluoropolyol-coated 158-MHz dual delay line SAW vapor sensors are converted to partition coefficients by this method, and these results are compared with partition coefficients determined by gas-liquid chromatography. These two methods rank the vapors in the same order of increasing sorption, but individual partition coefficient values are not always in precise agreement. The influence of temperature and gas-phase vapor concentration on vapor sorption is also examined.

Grate, J.W.; Snow, A.; Ballantine, D.S. Jr.; Wohltjen, H.; Abraham, M.H.; McGill, R.A.; Sasson, P.

1988-05-01

165

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

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

2013-07-01

166

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

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

2012-07-01

167

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

... true Default Factors for Petroleum Products and Natural Gas Liquids 1 2...GAS REPORTING Suppliers of Petroleum Products Pt. 98, Subpt. MM, Table...Part 98—Default Factors for Petroleum Products and Natural Gas Liquids 1...

2014-07-01

168

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

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

2011-07-01

169

Analysis of post-harvest fungicides by micellar electrokinetic chromatography.  

PubMed

A method based on solid-phase extraction (SPE) and micellar electrokinetic chromatography (MEKC) was developed for the simultaneous determination of carbendazim, imazalil, methylthiophanate, O-phenylphenol, prochloraz, procimidone, thiabendazole and triadimefon residues in grape, lettuce, orange and tomato. Selectivity and resolution were studied changing the pH and the concentration of the buffer, the type and concentration of surfactant and the methanol content in the mobile phase. A buffer consisting of 4 mM borate with 75 mM sodium cholate (pH 9.2) gave the best results. The recoveries of the fungicides in spiked fruit and vegetable samples ranged from 30 to 105%, and the limits of detection were between 0.1 and 1 mg kg(-1). The reproducibility and repeatability of the combination of SPE pretreatment and MEKC were good for all the compounds, except for imazalil and O-phenylphenol in oranges, due to some matrix compounds interfering with the separation. The method was applied to post harvest treated samples, and the fungicides were sometimes detected at concentration levels lower than maximum residue limits (MRLs). PMID:11521888

Rodríguez, R; Picó, Y; Font, G; Mañes, J

2001-07-27

170

High Performance Liquid Chromatography of Some Analgesic Compounds: An Instrumental Analysis Experiment.  

ERIC Educational Resources Information Center

Background information, procedures, and results are provided for an experiment demonstrating techniques of solvent selection, gradient elution, pH control, and ion-pairing in the analysis of an analgesic mixture using reversed-phase liquid chromatography on an octadecylsilane column. Although developed using sophisticated/expensive equipment, less…

Haddad, Paul; And Others

1983-01-01

171

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 here the application of this method to gold nanocrystals stabilized by thiols. Alternate recycling tool. For example, after recycling processes an initially broad and chromatographic feature from a gold

Richards-Kortum, Rebecca

172

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 ...

173

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...

174

Quantitative analysis of dimethyl titanocene by iodometric titration, gas chromatography and NMR  

Microsoft Academic Search

In this study we report the use of an automated iodometric titration method and a novel gas chromatography (GC) method for the quantitative analysis of dimethyl titanocene (DMT), a key raw material in drug synthesis. Both approaches are based on the reaction of DMT in toluene or tetrahydrofuran solutions with iodine. In the case of iodometric titration, excess iodine is

Anant Vailaya; Tao Wang; Yadan Chen; Mark Huffman

2001-01-01

175

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

176

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 ...

177

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...

178

Advancement and Application of Gas Chromatography Isotope Ratio Mass Spectrometry Techniques for Atmospheric Trace Gas Analysis  

Microsoft Academic Search

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

Brian M Giebel

2011-01-01

179

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

National Technical Information Service (NTIS)

Six samples of core segments from Tank 101-SY were analyzed for chelators, chelator fragments, and several carboxylic acids by derivatization gas chromatography/mass spectrometry. The major components detected were ethylenediaminetetraacetic acid, nitroso...

J. A. Campbell, B. D. Lerner, R. M. Bean, K. E. Grant, R. B. Lucke

1994-01-01

180

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

181

Stereospecific analysis of triacyl- sn -glycerols by chiral high-performance liquid chromatography  

Microsoft Academic Search

A method for the stereospecific analysis of triacyl-sn-glycerols by high-performance liquid chromatography (HPLC) on a chiral column is described. Triacyl-sn-glycerols were partially degraded with ethyl magnesium bromide, and the monoacylglycerols produced were separated as 1- and\\u000a 2-monoacylglycerol fractions by thin-layer chromatography on boric acid-impregnated silica gel plates. The 1-monoacylglycerols\\u000a were resolved intosn-1 andsn-3 monoacylglycerol fractions by HPLC on a chiral

Toru Takagi; Yasuhiro Ando

1991-01-01

182

Supplementary Data: Monosaccharide Composition and Linkage Analysis of RPS Glycosyl composition analysis was done by gas chromatography-mass  

E-print Network

composition analysis was done by gas chromatography-mass spectrometry (GC-MS) of the monosaccharide alditol in 4N TFA at 100o C (4 hr), resulting monosaccharides were reduced with NaBH4, acetylated in pyridine/acetic anhydride and analyzed on a DB-1 capillary column. Linkage analysis was done by GC-MS of the partially

Bush, C. Allen

183

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

184

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

185

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

E-print Network

of Pseudomonas spp. , Vibrio spp. , Achromobacter Moraxella spp. , and Coryneforms (Table 2), while warm-water fish carry mostly Micrococcus spp. , coryneforms, and Bacillus spp. Fish stored on ice Table 1. Total viable microbial numbers(20 C) from marine... '0 0 4 0 C Ul U 0 0 '0 0 0 QI C Ul U U! develop a microflora that is dominated by Pseudomonas spp. This was demonstrated by Adams et al. (1964). The microbial population of freshly caught sole (off the Northern California coast) consisted...

Scorah, Craig Darrell Allen

2012-06-07

186

Saturation region of helium ionization detector for gas-solid and gas-liquid chromatography  

Microsoft Academic Search

In the saturation region of the helium detector field intensity, the detector response is independent of the electrical field. In this region (at applied potential between 200 to 2000 volts per centimeter of electrode surface) the detector is operated at a low background current, and a low noise level, but it still exhibits a stable and sensitive response. The detector

Fikry F. Andrawes; Roswitha S. Brazell; Everett K. Gibson

1980-01-01

187

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

188

Evaluation of gas-liquid chromatography (GLC) for rapid detection of Clostridium difficile in fecal specimens.  

PubMed

Clostridium difficile intestinal infection is a major nosocomial hazard in patients receiving antimicrobial therapy. Rationale for rapid diagnosis include lifesaving antimicrobial therapy in patients with severe colitis and early isolation measures for transmission control. We have therefore analysed the sensitivity, specificity and predictive value of GLC identification of isocaproic acid in diarrheic stools from adult hospitalized patients in comparison with selective fecal culture on Cycloserine Cefoxitin Fructose Agar. During the study period, the prevalence of positive culture for C. difficile was 38/595 fecal specimens (6.4%). Compared with culture, GLC had a sensitivity of 24/38 (63%) and a specificity of 524/557 (94%). The predictive value of a positive GLC was 24/57 (42%) and of a negative GLC was 524/538 (97%). Measurement of the isocaproic acid peak height did not allow determination of a cutt-off value improving the test accuracy. The sensitivity of detection of isocaproic acid in stools by GLC is too low to be used as screening test for C. difficile infection. However, in a low prevalence population, a positive GLC test increased the pre-test probability of infection sevenfold. PMID:7597879

Nonhoff, C; Struelens, M J; Serruys, E

1995-01-01

189

Analysis of phytosterols and phytostanols in enriched dairy products by Fast gas chromatography with mass spectrometry.  

PubMed

A Fast gas chromatography and mass spectrometry method for plant sterols/stanols analysis was developed, using a short capillary gas chromatography column (10 m × 0.1 mm internal diameter × 0.1 ?m film thickness) coated with 5% diphenyl-polysiloxane. A silylated mixture of the main plant sterols/stanols standards (?-sitosterol, campesterol, stigmasterol, campestanol, sitostanol) was well separated in 1.5 min, with a good peak resolution (>1.4, determined on a critical chromatographic peak pair (?-sitosterol and sitostanol)), repeatability (<13%), and sensitivity (<0.017 ng/mL). The suitability of this Fast chromatography method was tested on plant sterols/stanols-enriched dairy products (yogurt and milk), which were subjected to lipid extraction, cold saponification, and silylation prior to injection. The analytical performance (sensitivity < 0.256 ng/mL and repeatability < 10.36%) and significant reduction of the analysis time and consumables demonstrate that Fast gas chromatography-mass spectrometry method could be also employed for the plant sterols/stanols analysis in functional dairy products. PMID:25069661

Inchingolo, Raffaella; Cardenia, Vladimiro; Rodriguez-Estrada, Maria Teresa

2014-10-01

190

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

191

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

192

Gas-liquid nucleation in nonideal molecular systems  

NASA Astrophysics Data System (ADS)

Nucleation is the initial step of a first order phase transition. In this thesis, some aspects of gas-liquid nucleation in systems of atmospheric importance are investigated. Nucleation is part of the gas-to-particle transition in the atmosphere. The gaseous pollutants released in the atmosphere due to human activities affect the transition processes an thus the size distribution and chemical properties of aerosol particles. Also the properties and appearance of clouds are affected. Aerosol particles and clouds have profound effects on e.g. the climate change, ozone depletion and acidification. Thermal collisions are generally used as a model of the nucleation process. Clusters are formed by kinetic collisions and their decay rates depend on their formation energies. If a cluster undergoes sufficient amount of collisions, it forms a droplet, which tends to grow further. In this study, kinetics of one- and two- component steady-state nucleation is investigated by solving the birth-death equations numerically. The validity of some of the commonly used approximations concerning nucleation kinetics are tested. The approximations are found to work well in most cases. The present theories fail in predicting the formation energies of small and non-ideal clusters. It is shown, that nucleation rates calculated with different models for the formation energy differ significantly in conditions corresponding to accidental ammonia release. Sulphuric acid-water mixture is considered to be one of the most important nucleating vapour systems in atmosphere. Sulphuric acid molecules are bound to hydrates, small clusters that contain a few water molecules. Hydrates play an important role in the nucleation process. To predict the formation energies of the hydrates, molecular-level effects have to be taken into account. The ab initio study of small sulphuric acid-water cluster included in the thesis is the first step towards understanding the properties of the hydrates.

Arstila, Hanna Tuula Katariina

193

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...

194

Phosphoinositide analysis by liquid chromatography-mass spectrometry.  

PubMed

The phosphoinositides are a highly dynamic group of molecules implicated in many cellular control processes; however, the analysis of many of these structures has proven very difficult and time-consuming, with limited sensitivity and/or discrimination. Recent developments in LCMS now provide the prospect of routine structural and quantitative analysis of all the known phosphoinositides (and possibly some as yet unidentified structures) at high sensitivity in any biological sample. The procedures described here give very high extraction recovery from a variety of biological matrices and enable chromatographic resolution of most phosphoinositides as their native structures. When coupled with the accurate mass and fragmentation capabilities of an MS, full structural and isomeric identification can be achieved. PMID:20645190

Pettitt, Trevor R

2010-01-01

195

Gas–liquid flow in stirred reactors: Trailing vortices and gas accumulation behind impeller blades  

Microsoft Academic Search

In a gas–liquid stirred reactor, gas tends to accumulate in low-pressure regions behind the impeller blades. Such gas accumulation significantly alters impeller performance characteristics. We have computationally investigated gas–liquid flow generated by a Rushton (disc) turbine. Rotating Rushton turbine generates trailing vortices behind the blades, which influence the gas accumulation in the impeller region. Characteristics of these trailing vortices were

Vivek V. Ranade; Vaibhav R. Deshpande

1999-01-01

196

GAS-LIQUID FLOW IN STIRRED REACTORS: Trailing Vortices and Gas Accumulation behind Impeller Blades  

Microsoft Academic Search

In a gas-liquid stirred reactor, gas tends to accumulate in low-pressure regions behind theimpeller blades. Such gas accumulation forming so-called gas cavities, significantly altersimpeller performance characteristics. We have computationally investigated gas-liquid flowgenerated by a Rushton turbine. Rotating Rushton turbine generates trailing vortices behind theblades, which enhance the gas accumulation. Characteristics of these trailing vortices were firstinvestigated by considering a...

Vivek V. Ranade

1998-01-01

197

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

198

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

199

Gas chromatography/matrix isolation-infrared spectrometry for air-sample analysis  

SciTech Connect

The report describes the application of gas chromatography/matrix-isolation 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 samples. The emphasis of the report is on the use of GC/MI-IR to identify semivolatile organic compounds in these extracts. The complementarity of GC/MI-IR spectrometry and conventional electron-impact ionization gas chromatography/mass spectrometry (EI-GC-MS) is illustrated. The capability of GC/MI-IR to discriminate between isomeric compounds that are difficult to separate chromatographically and to distinguish by EI-GC/MS is demonstrated. Preliminary results regarding the potential of GC/MI-IR spectrometry for the quantitative analysis of polycyclic aromatic hydrocarbons in air sample extracts are presented. Problem areas and modifications of a commercial GC/MI-IR system are discussed.

Childers, J.W.

1990-10-01

200

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

201

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

202

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

203

[Headspace analysis of volatile organic compounds (VOC) in drinking water by the method of gas chromatography].  

PubMed

In the paper there is presented a methodology of analysis of headspace 52 volatile organic compounds in drinking water by the method of gas chromatography with the use of the chromatograph "Crystal 5000.2" with three detectors and automatic attachment Lab Hut 200N NT-200 for the preparation of the sample water and vapor phase input. The lower limit of detection for all compounds in the 2-10 times lower than that of the corresponding standard value. PMID:25051750

Sotnikov, E E; Zagaynov, V F; Mikhaylova, R I; Milochkin, D A; Ryzhova, I N; Kornilov, I O

2014-01-01

204

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

Microsoft Academic Search

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

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

2004-01-01

205

Discrimination of genetically modified poplar clones by analytical pyrolysis–gas chromatography and principal component analysis  

Microsoft Academic Search

Analytical pyrolysis combined with gas chromatography and mass spectrometry (Py-GC–MS) is a relatively rapid (1–3h) method for the investigation of polymers. Various wood tissues from transgenic poplar clones and from control samples have been subjected to a screening test by Py-GC–MS. Pyrolysis products from lignin- and carbohydrate-derived pyrolysis products were subjected to multivariate principal component analysis (PCA). The first three

Dietrich Meier; Ingrid Fortmann; Jürgen Odermatt; Oskar Faix

2005-01-01

206

Development of Multi-scale Multiphase Flow Equation and Thermodynamic Modeling of Gas-liquid Interface  

NASA Astrophysics Data System (ADS)

A gas-liquid interface contains various complex physics and unknown phenomena related to thermodynamics, electromagnetics, hydrodynamics, and heat and mass transfer. Therefore, a modeling of gas-liquid interface is one of key issues of the numerical research on multiphase flows. Currently, the Continuum Surface Force model (CSF) is popular to model a gas-liquid interface in computational fluid dynamics. However, the CSF model cannot explain the physics of the gas-liquid interface because it is derived through a mechanical energy balance at the interface. In this study, by assuming a gas-liquid interface as a fluid-membrane with a thin but finite thickness, we develop a new gas-liquid interface model based on thermodynamics via mathematical approach. In particular, we derive an equation of free energy based on a lattice gas model including the effect of the electric double layer caused by a contamination on the interaction between the bubble interfaces. Finally, we derive a set of new governing equations for fluid motion based on a mesoscopic concept. The free energy is incorporated into the Navier-Stokes equation as new terms by using Chapman-Enskog expansion. Moreover, by using the new governing equation, we derive the jump condition at the gas-liquid interface based on thermodynamics. Then, we compare the obtained thermodynamic jump condition with the conventional one. As a result, we reveal that the conventional jump condition is true under a specific condition and that thermodynamic jump condition provides more general formalism than the conventional one.

Yonemoto, Yukihiro; Kunugi, Tomoaki

207

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 ...

208

Analysis of positional isomers of hydroxylated aromatic cytokinins by micellar electrokinetic chromatography.  

PubMed

A micellar electrokinetic chromatography (MEKC) method was developed for the separation of six positional isomers of hydroxylated aromatic cytokinins (topolin and topolin riboside), including ortho-topolin, meta-topolin, para-topolin, ortho-topolin riboside, meta-topolin riboside, and para-topolin riboside. Optimum resolution and analysis time (ca. 20 min) for the six aromatic cytokinin standards were achieved with a running buffer at pH 8.0 consisting of 20 mM boric acid, 50 mM sodium dodecyl sulfate (SDS), and 20% v/v methanol. The method has good reproducibility and has been successfully applied to detect the presence of a putative ortho-topolin in coconut water extract sample purified using C(18) and mixed-mode solid-phase extraction (SPE) columns. Other advantages of this MEKC method are short analysis time, low solvent consumption, and separation of positional isomers which could be achieved by a simple aqueous buffer system without the use of expensive chromatographic columns. In addition, a high-performance liquid chromatography (HPLC) method with baseline separation of the six topolin and topolin riboside standards was developed for the confirmation of the endogenous ortho-topolin in coconut water sample. Finally, the presence of ortho-topolin was further confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) based on its characteristic fragmentation pattern. PMID:15800967

Ge, Liya; Yong, Jean Wan Hong; Tan, Swee Ngin; Yang, Xin Hao; Ong, Eng Shi

2005-05-01

209

Ion Chromatography.  

ERIC Educational Resources Information Center

Accurate for the analysis of ions in solution, this form of analysis enables the analyst to directly assay many compounds that previously were difficult or impossible to analyze. The method is a combination of the methodologies of ion exchange, liquid chromatography, and conductimetric determination with eluant suppression. (Author/RE)

Mulik, James D.; Sawicki, Eugene

1979-01-01

210

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

211

Carbon-based sorbents in chromatography. New achievements.  

PubMed

The newest results in the employment of carbon-based composites in various chromatographic techniques such as gas-liquid chromatography, high-performance liquid chromatography and electrically driven separation techniques for the separation, quantitative determination and identification of a wide variety of compounds in complicated matrices are compiled. The results are concisely described and critically evaluated. The future trends in the application of carbon-based compounds in the chromatographic separation methods are briefly discussed. PMID:19137510

Cserháti, T

2009-02-01

212

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

213

[Gas-liquid mass transfer in three-phase inverse turbulent bed reactor].  

PubMed

The characteristics of gas-liquid mass transfer of three-phase system comprising air, tap water/wastewater, and hollow glass beads were studied in a laboratory-scale inverse turbulent bed reactor. The influence of operational factors and liquid property on volumetric liquid-phase mass transfer coefficient kLa was investigated under the conditions of superficial gas velocity (0.53mm xs(-1) - 10mx s(-1) solid hold-up (0 - 0.3), and superficial liquid velocity (0 - 0.2mm x s(-1)). The results showed that the coefficient value was 0.0456 - 1. 414min -, which increased with superficial gas velocity and liquid velocity. The coefficient attained the maximum value at solid hold-up of 0.05 - 0.08. Compared with the coefficient value in tap water, that in synthetic wastewater and industrial wastewater is decreased by 39.0% and 50.9%, respectively. These data have provided a basis for the process analysis and mathematical simulation of inverse turbulent bed reactor. PMID:17366900

Jin, Ren-Cun; Zheng, Ping; Chen, Jian-Wei; Tu, Zhan

2007-01-01

214

Stereodynamics in state-resolved scattering at the gas–liquid interface  

PubMed Central

Stereodynamics at the gas–liquid interface provides insight into the important physical interactions that directly influence heterogeneous chemistry at the surface and within the bulk liquid. We investigate molecular beam scattering of CO2 from a liquid perfluoropolyether (PFPE) surface in vacuum [incident energy Einc = 10.6(8) kcal/mol, incident angle ?inc = 60°] to specifically reveal rotational angular-momentum directions for scattered molecules. Experimentally, internal quantum state populations and MJ distributions are probed by high-resolution polarization-modulated infrared laser spectroscopy. Analysis of J-state populations reveals dual-channel scattering dynamics characterized by a two-temperature Boltzmann distribution for trapping–desorption and impulsive scattering. In addition, molecular dynamics simulations of CO2 + fluorinated self-assembled monolayers have been used to model CO2 + PFPE dynamics. Experimental results and molecular dynamics simulations reveal highly oriented CO2 distributions that preferentially scatter with “top spin” as a strongly increasing function of J state. PMID:18678907

Perkins, Bradford G.; Nesbitt, David J.

2008-01-01

215

Fundamentals of multiphase, gas-solid and gas-liquid flows in porous media  

NASA Astrophysics Data System (ADS)

This thesis is concerned with fundamentals and applications of multiphase and particulate flows. The study contains three parts covering gas-liquid flows through porous media, gas-solid flows and Chemical-Mechanical Polishing (CMP). A continuum model for multiphase fluid flows through poro-elastic media is developed. It is shown that the present theory leads to the extended Darcy's law and contains, as its special case, Biot's theory of saturated poro-elastic media. The capillary pressure formulation derived from the new model is used and the equation governing the evolution of the saturation and its temporal variation in porous media is derived. The resulting nonlinear diffusion equation is then solved numerically. The results show that the capillary hysteresis occurs when the temporal variation of saturation is included. Application of the developed model to CO2 sequestration is discussed. Computer simulations of dilute Gas-Solid flows in complex geometry regions are studied. A procedure for handling particle trajectory analysis in unstructured grid is developed. Examples of particle transport and removal in human lung and hot-gas cleaning systems are presented. The simulation results for the human lung show that the capture efficiency is affected by the turbulence in the upper three bifurcation airways. Computer simulations of gas-solid flows in hot-gas cleaning for a demonstration scale filtration system is studied in details. Alternative designs of the filter vessel are proposed. The corresponding vessel performance are numerically simulated.

Mazaheri, Ali Reza

216

Gas Chromatography -Mass Spectrometry  

E-print Network

GCMS - 1 Gas Chromatography - Mass Spectrometry GC-MS ANALYSIS OF ETHANOL AND BENZENE IN GASOLINE Last updated: June 17, 2014 #12;GCMS - 2 Gas Chromatography - Mass Spectrometry GC-MS ANALYSIS). The goal of this experiment is to separate the components in a sample of gasoline using Gas Chromatography

Nizkorodov, Sergey

217

Ion chromatography as a measurement device in continuous flow analysis of ice cores  

NASA Astrophysics Data System (ADS)

Melter-based continuous chemical analysis of ice cores has been increasingly employed in ice core research for fast, high resolution measurements of the chemical impurities in snow and ice. In continuous flow analysis (CFA), a heated melter generates uncontaminated flowing streams of ice core meltwater which are channeled directly into measurement devices, such as spectrophotometers, mass spectrometers and flow injection analyzers. These devices essentially serve as on-line and quantitative detectors for the melter-generated flow streams. Ion chromatography (IC) has been the preferred analytical technique for the determination of major chemical impurities in ice cores. Using IC as the measurement or detection technique for continuous flow melter analysis would provide an analytical system for measurement of all major chemical impurities in ice cores. We have constructed such a system by interfacing an ice core melter with several ion chromatographs. This technique (CFA-IC) takes advantage of the fast sample preparation and sub-sampling speed provided by a melter and the all-ion capability with low detection limits of ion chromatography. Initial testing and ice core analysis demonstrate that the CFA-IC technique is capable of (1) measuring all major ions, (2) high analysis speed as a result of reduced sample preparation time, and (3) high temporal resolution while requiring less ice than the conventional discrete sampling method.

Budner, D. M.; Cole-Dai, J.; Ferris, D.

2005-12-01

218

Gas–liquid flow generated by a Rushton turbine in stirred vessel: CARPT\\/CT measurements and CFD simulations  

Microsoft Academic Search

In this work, computer-automated radioactive particle tracking (CARPT), computed tomography (CT) and computational fluid dynamic (CFD) based models were used to investigate gas–liquid flow generated by a Rushton turbine. CARPT and CT measurements were carried out in a gas–liquid stirred vessel operating in two different flow regimes and captured the quantitative Eulerian information of gas–liquid flow. The CARPT data was

A. R. Khopkar; A. R. Rammohan; V. V. Ranade; M. P. Dudukovic

2005-01-01

219

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

220

Gene flow versus selection pressure and ancestral differentiation in the composition of species: Analysis of populational variation of Juniperus ashei buch. Using terpenoid data  

Microsoft Academic Search

Summary Twenty-four populations ofJuniperus ashei were sampled throughout the range of this taxon and the terpenoids of the foliage were analyzed by gas\\/liquid chromatography. Population differentiation was investigated by analysis of variance and numerical taxonomy. Three south Texas and one Mexican population clustered together with the rest of the taxon appearing fairly uniform. No evidence was found of hybridization or

R. P. Adams

1975-01-01

221

Vertically-Vibrated Gas-Liquid Interfaces: Surface Deformation and Breakup  

E-print Network

In his pioneering work of 1831, Faraday demonstrated that a vertically vibrated gas-liquid interface exhibits a period-doubling bifurcation from a flat state to a wavy configuration at certain frequencies or amplitudes. Typical experiments performed using thin layers of water produce "Faraday ripples", modest-amplitude nonlinear standing waves. Later experiments by Hashimoto and Sudo (1980) and Jameson (1966) as well as those performed in the present study show that much more dramatic disturbances can be generated at the gas-liquid free surface under certain ranges of vibration conditions. This breakup mechanism was examined experimentally using deep layers of polydimethylsiloxane (PDMS) silicone oils over a range of viscosity and sinusoidal, primarily axial vibration conditions that can produce dramatic disturbances at the gas-liquid free surface. Large-amplitude vibrations produce liquid jets into the gas, droplets pinching off from the jets, gas cavities in the liquid from droplet impact, and bubble transp...

O'Hern, T J; Brooks, C F; Shelden, B; Torczynski, J R; Kraynik, A M; Romero, L A; Benavides, G L

2010-01-01

222

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

223

High-performance anion-exchange chromatography with pulsed amperometric detection for carbohydrate analysis of glycoproteins.  

PubMed

High-performance anion-exchange chromatography with pulsed amperometric detection (HPAE-PAD) is an established technique for the carbohydrate analysis of glycoproteins. HPAE-PAD is routinely used for determinations of monosaccharide, sialic acid, mannose-6-phosphate (M-6-P), and oligosaccharide contents of a glycoprotein. This is true for both the initial investigation of a glycoprotein and routine assays of recombinant therapeutic glycoproteins. This contribution reviews the fundamentals of HPAE-PAD, recent technological improvements, and advances in the last ten years in its application to carbohydrate analysis of glycoproteins. The application areas reviewed include monosaccharide determinations, sialic acid determinations, M-6-P determinations, sugar alcohol determinations, analysis of polysialic acids, neutral and charged oligosaccharide analysis, following glycosidase and glycosyltransferase reactions, and coupling HPAE-PAD to mass spectrometry (MS). PMID:24010833

Rohrer, J S; Basumallick, L; Hurum, D

2013-07-01

224

Qualitative and quantitative analysis of vetiver essential oils by comprehensive two-dimensional gas chromatography and comprehensive two-dimensional gas chromatography/mass spectrometry.  

PubMed

Vetiver essential oils (VEO) are important raw ingredients used in perfume industry, entering the formula of numerous modern fragrances. Vetiver oils are considered to be among the most complex essential oils, resulting most of the time in highly coeluted chromatograms whatever the analytical technique. In this context, conventional gas chromatography has failed to provide a routine tool for the accurate qualitative and quantitative analysis of their constituents. Applying comprehensive two-dimensional gas chromatography techniques (GC×GC-FID/MS) afforded the mean to separate efficiently vetiver oil constituents in order to identify them in a more reliable way. Moreover, this is the first time that a complete true quantitation of each constituent is carried out on such complex oils by means of internal calibration. Finally, we have studied the influence of the injection mode on the determined chemical composition, and showed that several alcohols underwent dehydration under defined chromatographic conditions (splitless mode) usually recommended for quantitation purposes. PMID:23522261

Filippi, Jean-Jacques; Belhassen, Emilie; Baldovini, Nicolas; Brevard, Hugues; Meierhenrich, Uwe J

2013-05-01

225

Characterization of annular two-phase gas-liquid flows in microgravity  

NASA Technical Reports Server (NTRS)

A series of two-phase gas-liquid flow experiments were developed to study annular flows in microgravity using the NASA Lewis Learjet. A test section was built to measure the liquid film thickness around the perimeter of the tube permitting the three dimensional nature of the gas-liquid interface to be observed. A second test section was used to measure the film thickness, pressure drop and wall shear stress in annular microgravity two-phase flows. Three liquids were studied to determine the effects of liquid viscosity and surface tension. The result of this study provide insight into the wave characteristics, pressure drop and droplet entrainment in microgravity annular flows.

Bousman, W. Scott; Mcquillen, John B.

1994-01-01

226

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

227

Determination of Np-237 by radiochemical neutron activation analysis combined with extraction chromatography.  

PubMed

A procedure for determination of 237Np, 238Pu, 239,240Pu and 241Pu in environmental samples is described. Neptunium-237 is determined using radiochemical neutron activation analysis with pre- and post-irradiation chemistry based on solvent extraction and extraction chromatography. 238Pu, 239,240Pu is determined using alpha spectrometry and 241Pu by liquid scintillation spectrometry. The vertical profiles of 237Np, 238Pu, 239,240Pu in bottom sediments from the Black Sea are presented. PMID:14987710

Kalmykov, St N; Aliev, R A; Sapozhnikov, D Yu; Sapozhnikov, Yu A; Afinogenov, A M

2004-01-01

228

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

229

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

230

High-performance thin-layer chromatography method for inositol phosphate analysis.  

PubMed

A simple and inexpensive high-performance thin-layer chromatography (HPTLC) method for the analysis of inositol mono- to hexakisphosphates on cellulose precoated plates is described. Plates were developed in 1-propanol-25% ammonia solution-water (5:4:1) and substance quantities as low as 100-200 pmol were detected by molybdate staining. Chromatographic mobilities of nucleotides and phosphorylated carbohydrates were also characterized. Charcoal treatment was employed to separate nucleotides from inositol phosphates with similar R(F) values prior to HPTLC analysis. Practical application of the HPTLC system is demonstrated by analysis of grain extracts from wild type and low-phytate mutant barley as well as phytate degradation products resulting from barley phytase activity. PMID:10677002

Hatzack, F; Rasmussen, S K

1999-12-24

231

Purification of high conductive liquid using gas-liquid phases discharge reactor  

Microsoft Academic Search

Water purification by streamer discharge using pulsed power generator under the high conductivity water containing pollutants has been investigated. A gas-liquid separated reactor was developed to treat high conductive solution. A wire electrode was placed in the gas phase and a plane electrode was immersed in the water. The pulsed high voltage generated by six stacked Blumlein line was applied

K. Takahashi; Y. Sasaki; S. Mukaigawa; K. Takaki; T. Fujiwara; N. Satta

2009-01-01

232

Bubble characteristics in a high-intensity gas\\/liquid contactor  

Microsoft Academic Search

Experimental studies on bubble sizes in a high-intensity gas\\/liquid contactor are described. The contactor utilizes cross flow of liquid at high velocities to generate small bubbles. The relatively limited previous literature on bubble formation in cross flow is first reviewed. Measurements using a video technique at the exit of a short version of the contactor and on a section of

B. Waldie; T. Johnston; W. K. Harris; C. Bell

1999-01-01

233

Duality of the gas-liquid flow regimes in bubble column reactors  

Microsoft Academic Search

The purpose of the present work was to examine the effect of design and working parameters of bubble column reactors on the formation and stability of the homogeneous and the heterogeneous bubbling regimes and to demonstrate the effect of bubbling regime transition on the hydrodynamic and mass transfer characteristics of gas-liquid beds in bubble column reactors. The factors determining the

J. Zahradník; M. Fialová; M. R?ži?ka; J. Drahoš; F. Kaštánek; N. H. Thomas

1997-01-01

234

Summary: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Proved Reserves  

E-print Network

current and projected U.S. energy demands. Shale gas development in Louisiana, Arkansas, Texas, Oklahoma at the end of 2008. This underscores the role of more efficient and effective shale gas explorationSummary: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Proved Reserves 2009 November 2010 U

Boyer, Elizabeth W.

235

Properties of hydrophobic free energy found by gas-liquid transfer  

PubMed Central

The hydrophobic free energy in current use is based on transfer of alkane solutes from liquid alkanes to water, and it has been argued recently that these values are incorrect and should be based instead on gas–liquid transfer data. Hydrophobic free energy is measured here by gas–liquid transfer of hydrocarbon gases from vapor to water. The new definition reduces more than twofold the values of the apparent hydrophobic free energy. Nevertheless, the newly defined hydrophobic free energy is still the dominant factor that drives protein folding as judged by ?Cp, the change in heat capacity, found from the free energy change for heat-induced protein unfolding. The ?Cp for protein unfolding agrees with ?Cp values for solvating hydrocarbon gases and disagrees with ?Cp for breaking peptide hydrogen bonds, which has the opposite sign. The ?Cp values for the enthalpy of liquid–liquid and gas–liquid transfer are similar. The plot of free energy against the apparent solvent-exposed surface area is given for linear alkanes, but only for a single conformation, the extended conformation, of these flexible-chain molecules. The ability of the gas–liquid hydrophobic factor to predict protein stability is tested and reasonable agreement is found, using published data for the dependences on temperature of the unfolding enthalpy of ribonuclease T1 and the solvation enthalpies of the nonpolar and polar groups. PMID:23319615

Baldwin, Robert L.

2013-01-01

236

Upward Gas-Liquid Flow in Concentric and Eccentric Annular Spaces  

E-print Network

facility with an annulus flow loop composed of a 5-1/2 in. outer-pipe and a 2-3/8 in. inner-pipe was used, with tap water as the liquid phase and compressed-air as the gas phase. This work’s objective was to phenomenologically characterize gas-liquid flow...

Cavalcanti de Sousa, Pedro

2013-12-09

237

Vertically-Vibrated Gas-Liquid Interfaces: Surface Deformation and Breakup  

Microsoft Academic Search

In his pioneering work of 1831, Faraday demonstrated that a vertically\\u000avibrated gas-liquid interface exhibits a period-doubling bifurcation from a\\u000aflat state to a wavy configuration at certain frequencies or amplitudes.\\u000aTypical experiments performed using thin layers of water produce \\

T. J. O'Hern; E. F. Romero; C. F. Brooks; B. Shelden; J. R. Torczynski; A. M. Kraynik; L. A. Romero; G. L. Benavides

2010-01-01

238

Vertically-Vibrated Gas-Liquid Interfaces: Surface Deformation and Breakup  

Microsoft Academic Search

In his pioneering work of 1831, Faraday demonstrated that a vertically vibrated gas-liquid interface exhibits a period-doubling bifurcation from a flat state to a wavy configuration at certain frequencies or amplitudes. Typical experiments performed using thin layers of water produce \\

T. J. O'Hern; E. F. Romero; C. F. Brooks; B. Shelden; J. R. Torczynski; A. M. Kraynik; L. A. Romero; G. L. Benavides

2010-01-01

239

Mixed refrigerants proven efficient in natural-gas-liquids recovery process  

Microsoft Academic Search

Lower processing temperatures for higher recoveries of natural gas liquids (NGL) leads to increasingly complex and expensive refrigeration techniques. This paper describes the mixed component refrigeration technique and that it has been proven as a viable alternative to the turboexpander plant. Mixed component refrigeration systems have been primarily used in applications such as LNG terminals and peak-shaving plants, where overall

Mac Kenzie

1985-01-01

240

Peptide-protein analysis and characterization by multidimensional liquid chromatography and capillary electrophoresis  

Microsoft Academic Search

This research was conducted to study the type of multidimensional liquid chromatography utilizing partitioning based chromatography in the first dimension. The “drifting peak” phenomenon was studied from the fundamental theory and practical viewpoint and various solutions were proposed and validated. Various types of two-dimensional HPLC which combine ion-exchange and reversed-phase chromatography or two different reversed-phase chromatography columns were explored to

Gang Huang

1998-01-01

241

Computer-assisted gas chromatography in the analysis of waste compounds resulting from coal gasification  

SciTech Connect

Newly developed modifications of the coal gasification processes produce greater quantities of unidentified waste compounds. Analysis of these compounds was easier if identification was a matching process. A standard solution of five polynuclear aromatic hydrocarbons was made and each was assigned retention indices values. Known compounds in the six different classes that had been detected by older gas chromatographic methods were analyzed and assigned retention indices values by interpolation from the standards. Unknown samples were then analyzed and the components were also given retention indices values by the same method. Values assigned to unknown compounds were matched with those of known chemicals thereby identifying the unknown substance. Samples containing hundreds of different compounds could now be quickly and accurately identified by a combination of gas chromatography and computer analysis.

Raye, J.

1988-01-01

242

Analysis of Soft Drinks: UV Spectrophotometry, Liquid Chromatography, and Capillary Electrophoresis  

NASA Astrophysics Data System (ADS)

Instrumental analysis students analyze commercial soft drinks in three successive laboratory experiments. First, UV multicomponent analysis is used to determine caffeine and benzoic acid in Mello YelloTM using the spectrophotometer's software and manually by the simultaneous equations method. The following week, caffeine, benzoic acid and aspartame are determined in a variety of soft drinks by reversed-phase liquid chromatography using 45% methanol/55% aqueous phosphate, pH 3.0, as the mobile phase. In the third experiment, the same samples are analyzed by capillary electrophoresis using a pH 9.4 borate buffer. Students also determine the minimum detection limits for all three compounds by both LC and CE. The experiments demonstrate the analytical use and limitations of the three instruments. The reports and prelab quizzes also stress the importance of the chemistry of the three compounds, especially the relationships of acid/base behavior and polarity to the LC and CE separations.

McDevitt, Valerie L.; Rodriguez, Alejandra; Williams, Kathryn R.

1998-05-01

243

Analysis of nucleosides and nucleotides in infant formula by liquid chromatography-tandem mass spectrometry.  

PubMed

A method for the simultaneous analysis of nucleosides and nucleotides in infant formula using reversed-phase liquid chromatography-tandem mass spectrometry is described. This approach is advantageous for compliance testing of infant formula over other LC-MS methods in which only nucleotides or nucleosides are measured. Following sample dissolution, protein was removed by centrifugal ultrafiltration. Chromatographic analyses were performed using a C18 stationary phase and gradient elution of an ammonium acetate/bicarbonate buffer, mass spectrometric detection and quantitation by a stable isotope-labelled internal standard technique. A single laboratory validation was performed, with spike recoveries of 80.1-112.9% and repeatability relative standard deviations of 1.9-7.2%. Accuracy as bias was demonstrated against reference values for NIST1849a certified reference material. The method has been validated for the analysis of bovine milk-based, soy-based, caprine milk-based and hydrolysed milk protein-based infant formulae. PMID:23559337

Gill, Brendon D; Indyk, Harvey E; Manley-Harris, Merilyn

2013-06-01

244

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

E-print Network

are imported from NORMAG Germany. New glass-flasks are made of borosilicate glass 3.3 volume 1 liter, with newGlass flask air sample analysis through Gas Chromatography in India: Implications for constraining is doing routine analysis of the glass flasks sampled at these two Indian stations. The ability to analyze

245

Analysis of Highly Polar Compounds of Plant Origin: Combination of Hydrophilic Interaction Chromatography and Electrospray Ion Trap Mass Spectrometry  

Microsoft Academic Search

The primary goal of metabolomic analysis is the unbiased relative quantification of every metabolite in a biological system. A number of different metabolite-profiling techniques must be combined to make this possible. Here we report the separation and analysis of highly polar compounds in a proof of concept study. Compounds were separated and analyzed using hydrophilic interaction liquid chromatography (HILIC) coupled

Vladimir V. Tolstikov; Oliver Fiehn

2002-01-01

246

Fundamentals of multiphase, gas-solid and gas-liquid flows in porous media  

NASA Astrophysics Data System (ADS)

This thesis is concerned with fundamentals and applications of multiphase and particulate flows. The study contains three parts covering gas-liquid flows through porous media, gas-solid flows and Chemical-Mechanical Polishing (CMP). A continuum model for multiphase fluid flows through poro-elastic media is developed. It is shown that the present theory leads to the extended Darcy's law and contains, as its special case, Biot's theory of saturated poro-elastic media. The capillary pressure formulation derived from the new model is used and the equation governing the evolution of the saturation and its temporal variation in porous media is derived. The resulting nonlinear diffusion equation is then solved numerically. The results show that the capillary hysteresis occurs when the temporal variation of saturation is included. Application of the developed model to CO2 sequestration is discussed. Computer simulations of dilute Gas-Solid flows in complex geometry regions are studied. A procedure for handling particle trajectory analysis in unstructured grid is developed. Examples of particle transport and removal in human lung and hot-gas cleaning systems are presented. The simulation results for the human lung show that the capture efficiency is affected by the turbulence in the upper three bifurcation airways. Computer simulations of gas-solid flows in hot-gas cleaning for a demonstration scale filtration system is studied in details. Alternative designs of the filter vessel are proposed. The corresponding vessel performance are numerically simulated. Chemical mechanical polishing (CMP) has become critical to the fabrication of advanced multilevel integrated circuit in microelectronic industry. The effect of course surface roughness of abrasive particles on the polishing rate in CMP is studied. The effects of slurry pH and double layer attraction and repulsion on chemical-mechanical polishing are also studied. It is shown that the slurry pH and colloidal forces significantly affect the removal rate in chemical mechanical polishing.

Mazaheri, Ali Reza

247

Rapid analysis for iodotyrosines and iodothyronines in thyroglobulin by reversed-phase liquid chromatography.  

PubMed

We describe a 10-min reversed-phase "high-pressure' liquid-chromatographic procedure for measuring tyrosine, monoiodotyrosine, diiodotyrosine, 3,5-diiodothyronine, 3,5,3'-triiodothyronine, 3,3',5'-triiodothyronine, and thyroxine. Resolution and quantitation of a mixture of these amino acids were excellent on LiChrosorb (Altex) RP-8 with isocratic elution (1.5 mL/min) with acetonitrile/water/glacial acetic acid (50/49/1 by vol). As little as 100 ng of each iodoamino acid could be detected and quantitated with a conventional 1-cm, flow-through spectrophotometric (254-nm) detector coupled to a 10-mV strip-chart recorder. Analyses for monoiodotyrosine, diiodotyrosine, 3,5,3'-triiodothyronine, and thyroxine in hog and beef thyroglobulin hydrolysates (sequential digestion with pronase and aminopeptidase) agreed well with results by anion-exchange chromatography and by competitive radioassays. To prevent interference by tryptophan in the analysis for diiodotyrosine, we batch-separated the iodoamino acids by anion-exchange chromatography before the procedure. The procedure we describe seems generally useful for detection and quantitation of thyroid hormones, thyroid hormone metabolites, and iodotyrosines. PMID:476925

Alexander, N M; Nishimoto, M

1979-10-01

248

Effect-directed analysis by high-performance liquid chromatography with gas-segmented enzyme inhibition.  

PubMed

A reversed-phase high-performance liquid chromatography system with UV-detector was equipped with an on-line acetylcholinesterase inhibition assay to achieve effect-directed analysis of potentially toxic samples. The enzyme activity was detected colorimetrically using Ellman's reagent. The inhibition and substrate conversion took place in glass capillaries at a 100 microL/min flow rate. Extra-column band spreading in the reaction coils reduces the sensitivity and separation power of biochemical detectors severely. Knitted reactors exhibited no reduction of longitudinal dispersion in the tested flow range. The implementation of air-segmentation allowed an extended inhibition and substrate conversion time without a significant loss of chromatographic resolution. The limit of detection of two model compounds carbofuran (carbamate) and paraoxon-ethyl (organophosphate) was determined to be 13 ng (injected mass) and 7.4 ng, respectively, applying an isocratic chromatography method. A mixture of five insecticides was separated by a gradient elution and the inhibitory effect on the enzyme activity could be detected with high resolution. The band width at half height of the enzyme inhibition detector signal after a reaction time of about 8 min or 4.2 m of capillary, respectively, increased only by a factor of 1.4 compared to the UV-detector signal. PMID:16197955

Fabel, Susanne; Niessner, Reinhard; Weller, Michael G

2005-12-16

249

Liquid chromatography-high-resolution mass spectrometry for quantitative analysis of gangliosides.  

PubMed

Gangliosides are a large family of glycosphingolipids that are abundant in the brain, and have been shown to affect neuronal plasticity during development, adulthood, and aging. We developed a fast, efficient, and sensitive liquid chromatography-mass spectrometry method to quantify eight different classes of gangliosides (GM(1), GM(2), GM(3), GD(3), GD(1a), GD(1b), GT(1b), GQ(1b)) in the brains of 2-day-old and 80-day-old Wistar rats. The gangliosides were extracted from rat brain using a modified Svennerholm and Fredman method. After ganglioside class separation using a hydrophilic high performance liquid chromatography (HPLC) column, the resolving power of the LTQ-Orbitrap mass spectrometer was used to extract and sum the major species of each ganglioside class, generating fully resolved extracted ion current peaks for both standards and samples. The flexibility and the specificity of this method are such that it can be applied to the analysis of other ganglioside species/classes not discussed in this paper, provided appropriate standards are available. The method had good repeatability (coefficient of variation 4.8-12.3%) and mean recoveries in the range 92-107%. PMID:19633991

Fong, Bertram; Norris, Carmen; Lowe, Edwin; McJarrow, Paul

2009-09-01

250

Determination of Phosphate in Cola Beverages Using Nonsuppressed Ion Chromatography: An Experiment Introducing Ion Chromatography for Quantitative Analysis  

NASA Astrophysics Data System (ADS)

The determination of inorganic anions was very difficult until the development of ion chromatography (IC). The two techniques for performing the conductivity detection are 'single column' or 'non suppressed' IC and 'suppressed' IC. Non suppressed IC (NSIC) is generally the selected technique because of its simple instrumentation: with the addition of a conductivity detector, any standard HPLC system can perform NSIC. Thus, according to the importance of IC, it is advisable the development of some IC experiments that could be integrated into existing laboratory courses in analytical chemistry. In this paper, the determination of phosphate in cola beverages by NSIC is introduced. Cola beverages are actually relatively rich in phosphoric acid, and may be considered as very suitable laboratory samples for the experiments. In the practical session, each student analyzes at least 3 different colas, and calculates the phosphate concentration and its relative standard deviation from replicate injections of the same cola brand (Repeatability). From the students' reports, the instructor evaluates the reproducibility using the results obtained by different students for the same cola brands. A relative difference among brands was detected in our experiments. The application of one-way-ANOVA to the collected results confirmed that the brands differ significantly.

Bello, M. A.; Gonzalez, A. Gustavo

1996-12-01

251

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

252

Liquid chromatography combined with mass spectrometry for 13C isotopic analysis in life science research.  

PubMed

Among the different disciplines covered by mass spectrometry, measurement of (13)C/(12)C isotopic ratio crosses a large section of disciplines from a tool revealing the origin of compounds to more recent approaches such as metabolomics and proteomics. Isotope ratio mass spectrometry (IRMS) and molecular mass spectrometry (MS) are the two most mature techniques for (13)C isotopic analysis of compounds, respectively, for high and low-isotopic precision. For the sample introduction, the coupling of gas chromatography (GC) to either IRMS or MS is state of the art technique for targeted isotopic analysis of volatile analytes. However, liquid chromatography (LC) also needs to be considered as a tool for the sample introduction into IRMS or MS for (13)C isotopic analyses of non-volatile analytes at natural abundance as well as for (13)C-labeled compounds. This review presents the past and the current processes used to perform (13)C isotopic analysis in combination with LC. It gives particular attention to the combination of LC with IRMS which started in the 1990's with the moving wire transport, then subsequently moved to the chemical reaction interface (CRI) and was made commercially available in 2004 with the wet chemical oxidation interface (LC-IRMS). The LC-IRMS method development is also discussed in this review, including the possible approaches for increasing selectivity and efficiency, for example, using a 100% aqueous mobile phase for the LC separation. In addition, applications for measuring (13)C isotopic enrichments using atmospheric pressure LC-MS instruments with a quadrupole, a time-of-flight, and an ion trap analyzer are also discussed as well as a LC-ICPMS using a prototype instrument with two quadrupoles. PMID:17853432

Godin, Jean-Philippe; Fay, Laurent-Bernard; Hopfgartner, Gérard

2007-01-01

253

Quality assessment of Cinnamomi Ramulus by the simultaneous analysis of multiple active components using high-performance thin-layer chromatography and high-performance liquid chromatography.  

PubMed

A novel and improved method for the quality assessment of Cinnamomi Ramulus was developed and completely validated. The method was established using fingerprint technology and simultaneous quantitative determination of six main marker compounds including coumarin, cinnamic alcohol, cinnamic acid, 2-methoxy cinnamic acid, cinnamaldehyde, and 2-methoxy cinnamaldehyde in the herbal medicine for the first time. A newly developed high-performance thin-layer chromatography method, which achieved simultaneous definition of five marker components by comparing the colors and retardation factor values of the bands in high-performance thin-layer chromatography, was first used for the authentication of Cinnamomi Ramulus. The fingerprints of 26 batches of herbal samples from different regions of China showed very similar chromatographic patterns that were evaluated by similarity analysis and hierarchical clustering analysis. In addition, six marker compounds were simultaneously determined using single standard to determine multiple components by the relative response factors. Compared with the external standard method, the new quantitative method was validated to determine multiple compounds in 26 batches of Cinnamomi Ramulus samples. All results demonstrated that the simple and rapid method could be effectively utilized for the quality control of Cinnamomi Ramulus. PMID:24964287

Wu, Xiaoxue; He, Jiao; Xu, Huarong; Bi, Kaishun; Li, Qing

2014-09-01

254

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

255

Detection of martian amino acids by chemical derivatization coupled to gas chromatography: in situ and laboratory analysis.  

PubMed

If there is, or ever was, life in our solar system beyond the Earth, Mars is the most likely place to search for. Future space missions will have then to take into account the detection of prebiotic molecules or molecules of biological significance such as amino acids. Techniques of analysis used for returned samples have to be very sensitive and avoid any chemical or biological contamination whereas in situ techniques have to be automated, fast and low energy consuming. Several possible methods could be used for in situ amino acid analyses on Mars, but gas chromatography would likely be the most suitable. Returned samples could be analyzed by any method in routine laboratory use such as gas chromatography, already successfully performed for analyses of organic matter including amino acids from martian meteorites. The derivatization step, which volatilizes amino acids to perform both in situ and laboratory analysis by gas chromatography, is discussed here. PMID:11605632

Rodier, C; Vandenabeele-Trambouze, O; Sternberg, R; Coscia, D; Coll, P; Szopa, C; Raulin, F; Vidal-Madjar, C; Cabane, M; Israel, G; Grenier-Loustalot, M F; Dobrijevic, M; Despois, D

2001-01-01

256

Uncertainty estimation related to analysis of volatile aromatic hydrocarbons by static headspace gas chromatography.  

PubMed

A study of the analysis of benzene, toluene, ethylbenzene and xylenes by static headspace gas chromatography illustrated the estimation of uncertainty associated with the influence of several parameters, such as preparation of the standard solutions, calibration of the instrument, recovery and limit of detection. The objective of the investigation was to indicate the contribution of each stage in the developed procedure on the uncertainty measurement of the determination of volatile aromatic hydrocarbons in surface and underground water. The uncertainty sources were identified and illustrated in an effect diagram. The data illustrated the evaluation of uncertainty by the quantification of the uncertainty arising separately from each source. It has been demonstrated that data can be used to estimate the uncertainty resulting from the combined effect of all sources. PMID:23885042

Pavlova, Antoaneta; Stoyanova, Olga; Ivanova, Pavlina; Dimova, Teodora

2014-08-01

257

Multiclass method for antimicrobial analysis in animal feeds by liquid chromatography-tandem mass spectrometry.  

PubMed

A rapid multiclass method that covers 50 antimicrobials from 13 different families in animal feeds was developed. Samples were extracted using a mixture of methanol, acetonitrile and a McIlvaine buffer combined with sonication. Feed extracts were simply diluted prior to injection, since the clean-up strategies that were tested, based on either solid-phase extraction or dispersive solid-phase extraction, were ineffective at minimizing matrix-related signal suppression/enhancement. Analysis was carried out by liquid chromatography coupled to tandem mass spectrometry using an electrospray ionization source operating in positive and negative modes. For the quantification, matrix-fortified standard calibration curves were used to compensate for matrix effects and losses in sample preparation. The method was validated in-house in pig, poultry and cattle feed matrices and showed satisfactory performance characteristics. Thus, the proposed approach was suitable for application in a routine high-throughput laboratory for the official control of feeds. PMID:23922055

Borràs, S; Companyó, R; Guiteras, J; Bosch, J; Medina, M; Termes, S

2013-10-01

258

High-performance liquid Chromatography/Mass spectrometry analysis of proanthocyanidins in foods and beverages.  

PubMed

Monomeric and oligomeric proanthocyanidins present in a range of plant-derived foods and beverages were separated by degree of polymerization and identified using a modified normal-phase high-performance liquid chromatography (HPLC) method coupled with on-line mass spectrometry (MS) analysis using an atmospheric pressure ionization electrospray chamber. In addition, ultraviolet (UV) and fluorescence detection were used to monitor the separation of proanthocyanidins, with fluorescence detection demonstrating both increased sensitivity and the ability to reduce interfering signals from other components present in the food and beverage matrices as compared to UV detection. This qualitative study demonstrates the ability of this HPLC/MS technique to separate singly and doubly linked procyanidins, prodelphinidins, and copolymer oligomers, including their galloylated derivatives, present in a range of food and beverage samples. PMID:10552707

Lazarus, S A; Adamson, G E; Hammerstone, J F; Schmitz, H H

1999-09-01

259

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

260

Indirect hydrogen analysis by gas chromatography coupled to mass spectrometry (GC-MS).  

PubMed

Gas chromatography (GC) is an analytical tool very useful to investigate the composition of gaseous mixtures. The different gases are separated by specific columns but, if hydrogen (H2 ) is present in the sample, its detection can be performed by a thermal conductivity detector or a helium ionization detector. Indeed, coupled to GC, no other detector can perform this detection except the expensive atomic emission detector. Based on the detection and analysis of H2 isotopes by low-pressure chemical ionization mass spectrometry (MS), a new method for H2 detection by GC coupled to MS with an electron ionization ion source and a quadrupole analyser is presented. The presence of H2 in a gaseous mixture could easily be put in evidence by the monitoring of the molecular ion of the protonated carrier gas. PMID:23893637

Varlet, V; Smith, F; Augsburger, M

2013-08-01

261

Analysis for urinary catecholamines by liquid chromatography with amperometric detection: methodology and clinical interpretation of results.  

PubMed

A method is presented for the quantitative analysis of urinary unconjugated norepinephrine, epinephrine, and dopamine as discrete entities. The procedure requires initial purification of the specimen on aluminum oxide and a boric acid-gel. We used "high-performance" reversed-phase paired-ion chromatography, with a flow-through amperometric cell as the detector. The CV was 6% for determination of norepinephrine, 11% for epinephrine, and 6% for dopamine monitored at physiologic concentrations of these compounds in urine. In a population study, urine specimens from 117 normal pediatric and adult subjects, 85 hypertensive patients, and 22 patients with surgically proved pheochromocytoma were analyzed. The specificity of the method for detection of pheochromocytoma was 100%, with a sensitivity of 97%. PMID:759019

Moyer, T P; Jiang, N S; Tyce, G M; Sheps, S G

1979-02-01

262

Analysis of anthocyanins in powdered berry extracts by planar chromatography linked with bioassay and mass spectrometry.  

PubMed

Major anthocyanins were extracted with acidified methanol and characterised in powdered berry extracts of bilberry, blueberry, chokeberry, açai berry and cranberry by HPTLC-Vis-MS for the first time. A combined 2-step normal phase separation was applied, first for separation of anthocyanins and secondly of anthocyanidins. Documentation was performed under white light illumination (transmission mode). In the powdered berry extracts, especially the 3-glucosides of delphinidin, cyanidin, malvidin and peonidin, further cyanidin glycosides and respective anthocyanidins were found. Calibration data revealed a good correlation, with r between 0.9988 and 0.9999. The repeatability of the sample analysis (n=3) was ?3.6%. Based on the results obtained, this method can be used for rapid routine quality control of powdered berry extracts. For confirmation of the results or characterisation of unknown anthocyanin zones, mass spectra were recorded. Chromatography was directly linked to the effect using DPPH(?) reagent and luminescent Aliivibrio fischeri bioassay. PMID:24176320

Cretu, Georgiana C; Morlock, Gertrud E

2014-03-01

263

Quantitative analysis of dimethyl titanocene by iodometric titration, gas chromatography and NMR.  

PubMed

In this study we report the use of an automated iodometric titration method and a novel gas chromatography (GC) method for the quantitative analysis of dimethyl titanocene (DMT), a key raw material in drug synthesis. Both approaches are based on the reaction of DMT in toluene or tetrahydrofuran solutions with iodine. In the case of iodometric titration, excess iodine is titrated with a standardized aqueous sodium thiosulfate solution to a potentiometric end-point for the determination of DMT concentration. Alternatively, GC is employed to measure the concentration of iodomethane, a product of the reaction between DMT and iodine, in order to determine the concentration of DMT in the solution. Excellent agreement between iodometric titration, GC and NMR results using several DMT samples confirms the accuracy of the two methods and strongly supports the use of either method as a replacement to the expensive NMR for quantitative DMT analysis. The relatively few sources of error associated with the two methods, their ubiquitous nature and ease of application in routine analysis make them the analytical methods of choice, among all. Both methods have been validated according to ICH requirements. The use of iodometric titration method for DMT analysis is demonstrated with a couple of applications. PMID:11377038

Vailaya, A; Wang, T; Chen, Y; Huffman, M

2001-06-01

264

Analysis and determination of oestrogen-active compounds in fructus amomi by the combination of high-speed counter-current chromatography and high performance liquid chromatography.  

PubMed

Amomum longiligulare or Amomum villosum showed oestrogenic activity. In the present study, oestrogen-active components in fructus amomi, the seeds of A. longiligulare were separated by high-speed countercurrent chromatography (HSCCC) using stepwise elution of eight mobile phases with gradient polarity and advanced separation by high performance liquid chromatography (HPLC). The results yielded 17 compounds with the amount of 8-138mg and a purity of 94.3-99.8% from a 3g ethanolic extract of fructus amomi. The chemical structures of the compounds were identified by ESI-MS and NMR spectra, in which eight diarylheptanoids were demonstrated as the main oestrogen-active compounds in the fructus amomi. Determination of the diarylheptanoids in fructus amomi from various origins showed that fructus amomi contains more than 0.5% total diarylheptanoids. The results showed that fructus amomi is a diarylheptanoids-rich food resource possessing oestrogen-activity. The combination method of HSCCC and HPLC can be applied for the analysis of bioactive compounds by detecting the corresponding bioactivity in the HSCCC fractions and separating the target compounds with HPLC. PMID:24686238

Ying, Hao; Liu, Jinpeng; Du, Qizhen

2014-05-01

265

Simultaneous analysis of fourteen tertiary amine stimulants in human urine for doping control purposes by liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry.  

PubMed

A method for the simultaneous screening and confirmation of the presence of fourteen tertiary amine stimulants in human urine by gas chromatography-mass spectrometry (GC-MS) in combination with liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed and validated. Solid phase extraction (SPE) and liquid-liquid extraction (LLE) approaches were utilized for the pre-treatment of the urine samples. The study indicated that the capillary temperature played a significant role in the signal abundances of the protonated molecules of cropropamide and crotethamide under positive ion electrospray ionization (ESI) conditions. In addition, comparison studies of two different pre-treatment approaches as well as the two ionization modes were conducted. The LODs of the developed method for all the analytes were lower than the minimum required performance limit (MRPL) as set forth in the World Anti-Doping Agency (WADA) technical document for laboratories. The human urine sample obtained after oral administration of prolintane.HCl was successfully analyzed by the developed method, which demonstrated the applicability and reliability of the method for routine doping control analysis. PMID:19951756

Lu, Jianghai; Wang, San; Dong, Ying; Wang, Xiaobing; Yang, Shuming; Zhang, Jianli; Deng, Jing; Qin, Yang; Xu, Youxuan; Wu, Moutian; Ouyang, Gangfeng

2010-01-01

266

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

267

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...

268

Extraction and quantitative analysis of elemental sulfur from sulfide mineral surfaces by high-performance liquid chromatography  

Microsoft Academic Search

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 sulfur resulting from the oxidation of arsenopyrite, pyrite, marcasite, chalcopyrite, and chalcocite under various conditions. An initial pretreatment to remove any sulfur already present

Molly M. McGuire; Robert J. Hamers

2000-01-01

269

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...

270

Quantitative analysis of sildenafil and desmethylsildenafil in human serum by liquid chromatography–mass spectrometry with minimal sample pretreatment  

Microsoft Academic Search

A simple, sensitive and specific liquid chromatography tandem mass spectrometry method with minimal sample pretreatment was developed for the simultaneous analysis of sildenafil and its metabolite desmethylsildenafil in human serum. Sample pretreatment consisted of adding a methanolic solution of the internal standard vardenafil to the samples. After vortexing and centrifugation the samples were directly injected onto the C18 column using

René M. Vos; Abdel Chahbouni; Arno Sinjewel; Eleonora L. Swart

2008-01-01

271

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...

272

Combined mass and heat transfer during nonisothermal absorption in gas-liquid slug flow  

SciTech Connect

A model of combined mass and heat transfer during nonisothermal gas absorption from a slug rising, in a channel filled with liquid is suggested. The expressions for coefficients of heat and mass transfer from a single slug are derived in the approximation of the thin concentration and heat boundary layers in a liquid phase. Under the assumptions of a perfect mixing of the dissolved -as in liquid plugs and uniform temperature distribution in liquid plugs, recurrent relations for the dissolved gas concentration and temperature in the n-th liquid plug and mass and heat fluxes from the n-th gas slug are derived. The total mass and heat fluxes in a gas-liquid slug flow are determined. In the limiting case of absorption without heat release the derived formulas recover the expressions for isothermal absorption in a gas-liquid slug flow.

Elperin, T.; Fominykh, A. [Ben-Gurion Univ. of the Negev, Beer Sheva (Israel). Dept. of Mechanical Engineering] [Ben-Gurion Univ. of the Negev, Beer Sheva (Israel). Dept. of Mechanical Engineering

1995-03-01

273

Quantitative analysis of diclazuril in animal plasma by liquid chromatography/electrospray ionization mass spectrometry.  

PubMed

A novel, sensitive and specific method for the quantitative determination of diclazuril in animal plasma using liquid chromatography combined with electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) with negative ion detection is presented. Extraction of the samples was performed with a rapid deproteinization step using acetonitrile. Chromatography of diclazuril and the internal standard was achieved on a Nucleosil ODS 5-microm column, using a gradient elution with 0.01 M ammonium acetate and acetonitrile. To obtain the highest sensitivity and specificity possible, the mass spectrometer was operated in the multiple reaction monitoring (MRM) mode. The method was validated according to the requirements defined by the European Community. Calibration curves using plasma fortified between 1-100 ng/mL and 100-2000 ng/mL showed good linear correlation (r >or= 0.9991, goodness-of-fit coefficient analysis of quality control samples at 50 and 1000 ng/mL was within 11.7%. The most striking advantage of the proposed method was the high sensitivity and specificity achieved. A limit of quantification of 1 ng/mL was obtained, for which the trueness and precision also fell within acceptable limits. Using a signal-to-noise ratio of 3:1, the limit of detection was calculated to be 0.03 ng/mL. The method has been successfully used for the quantitative determination of diclazuril in plasma samples from treated sheep, demonstrating the usefulness of the developed method for application in the field of pharmacology and pharmacokinetics. PMID:12125023

Croubels, Siska; Cherlet, Marc; De Backer, Patrick

2002-01-01

274

A three-dimensional CFD model for gas–liquid bubble columns  

Microsoft Academic Search

This paper discusses the development of a three-dimensional Euler–Lagrange CFD model for a gas–liquid bubble column. The model resolves the time-dependent, three-dimensional motion of small, spherical gas bubbles in a liquid. Our model incorporates all relevant forces acting on a bubble rising in a liquid, and accounts for two-way momentum coupling between the phases. The liquid-phase hydrodynamics are described using

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

1999-01-01

275

Separation of CO 2 from CH 4 by using gas–liquid membrane contacting process  

Microsoft Academic Search

The separation of carbon dioxide (CO2) from methane (CH4) by using a gas–liquid membrane contactor was studied in order to confirm the potential of the process. The experiments were performed in a membrane contactor constructed with 0.2?m pore size microporous PVDF hollow fibers. Pure water, aqueous sodium hydroxide (NaOH) solution and aqueous monoethanolamine (MEA) solution were employed as the absorbents.

Supakorn Atchariyawut; Ratana Jiraratananon; Rong Wang

2007-01-01

276

COMBINED EULERIAN-VOF-LAGRANGIAN METHOD FOR GENERAL GAS-LIQUID FLOW APPLICATIONS  

Microsoft Academic Search

This article summarizes the technical development and validation of a multiphase computational fluid dynamics (CFD) numerical method using a combined volume-of-fluid (VOF)\\/Lagrangian tracking model to analyze general dispersed multiphase-flow problems with free surfaces. The gas-liquid interfacial mass, momentum, and energy transfer are modeled by continuum surface mechanisms. A high-order TVD scheme is also implemented for capturing sharp interfaces between immiscible

Yen-Sen Chen; Huan-Min Shang; Paul Liaw; Chien-Pin Chen; Ten-See Wang

1996-01-01

277

Effect of pulsing on reaction outcome in a gas–liquid catalytic packed-bed reactor  

Microsoft Academic Search

A novel experiment is described for studying the effect of flow regime on reaction outcome for a consecutive-parallel reaction. By taking advantage of the convective nature of disturbances that grow into pulses in gas–liquid packed-bed reactors, it is shown that it is possible to compare reaction behavior for pulsing and trickling at the same flow rates. This contrasts previous studies

Ruiyun Wu; Mark J. McCready; Arvind Varma

1999-01-01

278

Desulfurization in the gas-continuous impinging stream gas–liquid reactor  

Microsoft Academic Search

An investigation is made to evaluate the flue gas desulfurization (FGD) by absorption in a gas-continuous impinging stream gas–liquid reactor recently developed for systems involving fast reaction(s) in liquid. The mixture of air and SO2 was used as the pseudo-flue gas and Ca(OH)2-water suspension as the absorbent. By employing horizontal two-impinging streams, the reactor is simple in structure with few

Yuan Wu; Qin Li; Fang Li

2007-01-01

279

Effect of Taylor vortices on calcium carbonate crystallization by gas–liquid reaction  

Microsoft Academic Search

The effects of Taylor vortices on the mean size, size distribution, and morphology of calcium carbonate crystallized by the reaction of gaseous carbon dioxide and aqueous calcium hydroxide were experimentally investigated in a Couette–Taylor reactor. Via the absorption of CO2 gas into pure water, the mass transfer coefficient of CO2 at the gas–liquid interface was measured relative to the rotating

Sung Hoon Kang; Sang Goo Lee; Wang Mo Jung; Min Chan Kim; Woo-Sik Kim; Chang Kyun Choi; Robert S Feigelson

2003-01-01

280

Gas-liquid phase-transfer catalysis; A new continuous-flow method in organic synthesis  

Microsoft Academic Search

A synthetic method, gas-liquid phase-transfer catalysis (GL-PTC0), is described. GL-PTC is a continuous-flow procedure where gaseous reagents flow through a molten phase-transfer (PT) catalyst supported on a solid; no solvent is used. Reactions may develop through new mechanistic pathways compared with those of classical conditions; moreover, the reactions often occur in very selective ways. Some typical syntheses carried out under

Pietro Tundo; Giovanni Moraglio; Francesco Trotta

1989-01-01

281

Energy Data Reports: crude petroleum, petroleum products, and natural gas liquids, 1979. Final summary  

Microsoft Academic Search

Data are presented on crude oil, refined petroleum products and natural gas liquids supply, disposition and stocks in the US for 1979. Production of crude petroleum (including lease condensate) in the US in 1979 averaged 8,552,000 barrels\\/day, a decrease of 155,000 barrels\\/day, or 1.8%, below the 1978 level, reports the Energy Information Administration, United States Department of Energy. Of the

1980-01-01

282

Gravity-induced density and concentration profiles in binary mixtures near gas–liquid critical lines  

Microsoft Academic Search

We have calculated gravity-induced density and concentration gradients using scaled equations of state fashioned after that of Leung and Griffiths for binary mixtures near gas–liquid critical lines. The mixtures considered here are those of helium-3 and helium-4 and of carbon dioxide and ethane. Our calculations show that the density profiles for both mixtures in any proportion of the components are

R. F. Chang; J. M. H. Levelt Sengers; T. Doiron; J. Jones

1983-01-01

283

Raman Spectra of Hydrogen and Deuterium Sulfides in the Gas, Liquid and Solid States  

Microsoft Academic Search

Raman spectra have been obtained for H2S and D2S as gas, liquid and solid. Only one frequency has been obtained in the gas and liquid although three are permitted by the selection principles. In the solids, a single line and a close doublet have been obtained. With the available infra-red and Raman data, it is not possible to make quantitative

George M. Murphy; John E. Vance

1938-01-01

284

Interpretation of gas–liquid reactive crystallization data using a size-independent agglomeration model  

Microsoft Academic Search

A CO2–BaCl2–H2O gas–liquid reactive crystallization system, depicted by a size-independent agglomeration model, was successfully used to explore the crystallization kinetics of barium carbonate crystals. The growth kinetics shows that growth rate is proportional to a 1.85 order of relative supersaturation and decreases with an increase in pH value. The agglomeration kernel is nearly proportional to the growth rate of barium

Pao-Chi Chen; S. M. Liu; C. J. Jang; R. C. Hwang; Y. L. Yang; J. S. Lee; J. S. Jang

2003-01-01

285

An electrically driven gas-liquid-liquid contactor for bioreactor and other applications  

Microsoft Academic Search

An electrically driven gas-liquid-liquid bioreactor is described here, in which an aqueous medium containing a biocatalyst is introduced as a discontinuous phase into an organic-continuous liquid phase containing a substrate to be converted by the biocatalyst. A gas discontinuous phase, which may be needed to provide oxygen or a gaseous substrate to the biocatalyst, is also introduced into the bioreactor.

Costas Tsouris; Abhijeet P. Borole; Eric N. Kaufman; David W. DePaoli

1999-01-01

286

Evaluation of ultrahigh-performance liquid chromatography columns for the analysis of unmodified and antisense oligonucleotides.  

PubMed

Ultrahigh-performance liquid chromatography has been used for the separation and analysis of unmodified and modified antisense oligonucleotides. For this reason, we tested various columns of low particle sizes in our analysis of unmodified and phosphorothioate oligonucleotides. The influence of both the type and concentration of ion-pair reagent on the retention of the studied biomolecules was tested. The developed methods were used for separation of unmodified oligonucleotides and to determine antisense oligonucleotides in human serum samples. The results proved that octadecyl and phenyl columns are the most selective in the resolution of oligonucleotides which differ in the position of single nucleotides in the sequence. The phenyl column was selected and applied for the analysis of phosphorothioate oligonucleotides in serum samples. The calibration plots showed good linearity within the test concentration ranges. The intra-day CV of the calibration curve slopes was in the range of 1.6 to 4.2 %. The limits of detection (LODs) were in the range of 0.11-0.16 ?g mL(-1), while the limit of quantification (LOQ) values were between 0.35 and 0.51 ?g mL(-1). PMID:24939137

Studzi?ska, Sylwia; Buszewski, Bogus?aw

2014-11-01

287

Toward sensitive and accurate analysis of antibody biotherapeutics by liquid chromatography coupled with mass spectrometry.  

PubMed

Remarkable methodological advances in the past decade have expanded the application of liquid chromatography coupled with mass spectrometry (LC/MS) analysis of biotherapeutics. Currently, LC/MS represents a promising alternative or supplement to the traditional ligand binding assay (LBA) in the pharmacokinetic, pharmacodynamic, and toxicokinetic studies of protein drugs, owing to the rapid and cost-effective method development, high specificity and reproducibility, low sample consumption, the capacity of analyzing multiple targets in one analysis, and the fact that a validated method can be readily adapted across various matrices and species. While promising, technical challenges associated with sensitivity, sample preparation, method development, and quantitative accuracy need to be addressed to enable full utilization of LC/MS. This article introduces the rationale and technical challenges of LC/MS techniques in biotherapeutics analysis and summarizes recently developed strategies to alleviate these challenges. Applications of LC/MS techniques on quantification and characterization of antibody biotherapeutics are also discussed. We speculate that despite the highly attractive features of LC/MS, it will not fully replace traditional assays such as LBA in the foreseeable future; instead, the forthcoming trend is likely the conjunction of biochemical techniques with versatile LC/MS approaches to achieve accurate, sensitive, and unbiased characterization of biotherapeutics in highly complex pharmaceutical/biologic matrices. Such combinations will constitute powerful tools to tackle the challenges posed by the rapidly growing needs for biotherapeutics development. PMID:25185260

An, Bo; Zhang, Ming; Qu, Jun

2014-11-01

288

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

289

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

290

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

291

Matrix diversion methods for improved analysis of perchlorate by suppressed ion chromatography and conductivity detection.  

PubMed

Two inline matrix diversion methods were developed for the sensitive analysis of perchlorate in a matrix comprising up to 1000 mg l(-1) of chloride, sulfate and bicarbonate ions using suppressed ion chromatography and conductivity detection. The first method used a cryptand C1 concentrator column, which exhibited a high selectivity for perchlorate ion over the other matrix anions. After retaining the sample anions in a concentrator column derivatized with a crytpand phase, a rinse step was implemented with a weak base to divert the matrix ions to waste while selectively retaining perchlorate in the concentrator column for subsequent analysis. The analysis was done using a 2mm IonPac AS16 or 2 mm IonPac AS20 separator column. The second method was a two-dimensional matrix diversion method with a focus on improving the detection sensitivity. The first dimension was used to achieve some resolution of the matrix ions from perchlorate. The perchlorate ion was then diverted into a concentrator column for subsequent analysis in the second dimension. By pursuing analysis using a 4mm IonPac AS16 or IonPac AS20 column in the first dimension and subsequently pursuing analysis using a 2mm IonPac AS16 or IonPac AS20 column format, excellent sensitivities were achieved when the first and second dimensions were operated at the same linear flow velocity (cm min(-1)). While sensitive detection of perchlorate in the low microg l(-1) regime was achieved by the above methods in the presence of matrix ions, superior recovery for perchlorate was demonstrated under a variety of matrix concentrations by the second method. PMID:17723390

Lin, Rong; De Borba, Brian; Srinivasan, Kannan; Woodruff, Andy; Pohl, Chris

2006-05-10

292

U.S. crude oil, natural gas, and natural gas liquids reserves 1995 annual report  

SciTech Connect

The EIA annual reserves report series is the only source of comprehensive domestic proved reserves estimates. This publication is used by the Congress, Federal and State agencies, industry, and other interested parties to obtain accurate estimates of the Nation`s proved reserves of crude oil, natural gas, and natural gas liquids. These data are essential to the development, implementation, and evaluation of energy policy and legislation. This report presents estimates of proved reserves of crude oil, natural gas, and natural gas liquids as of December 31, 1995, as well as production volumes for the US and selected States and State subdivisions for the year 1995. Estimates are presented for the following four categories of natural gas: total gas (wet after lease separation), nonassociated gas and associated-dissolved gas (which are the two major types of wet natural gas), and total dry gas (wet gas adjusted for the removal of liquids at natural gas processing plants). In addition, reserve estimates for two types of natural gas liquids, lease condensate and natural gas plant liquids, are 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 1995 is provided. 21 figs., 16 tabs.

NONE

1996-11-01

293

US crude oil, natural gas, and natural gas liquids reserves 1996 annual report  

SciTech Connect

The EIA annual reserves report series is the only source of comprehensive domestic proved reserves estimates. This publication is used by the Congress, Federal and State agencies, industry, and other interested parties to obtain accurate estimates of the Nation`s proved reserves of crude oil, natural gas, and natural gas liquids. These data are essential to the development, implementation, and evaluation of energy policy and legislation. This report presents estimates of proved reserves of crude oil, natural gas, and natural gas liquids as of December 31, 1996, as well as production volumes for the US and selected States and State subdivisions for the year 1996. Estimates are presented for the following four categories of natural gas: total gas (wet after lease separation), nonassociated gas and associated-dissolved gas (which are the two major types of wet natural gas), and total dry gas (wet gas adjusted for the removal of liquids at natural gas processing plants). In addition, reserve estimates for two types of natural gas liquids, lease condensate and natural gas plant liquids, are 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 1996 is provided. 21 figs., 16 tabs.

NONE

1997-12-01

294

A parametric study for high-efficiency gas-liquid separator design  

NASA Astrophysics Data System (ADS)

A gas liquid centrifugal separator is widely used in industry on account of its simple geometry and little maintenance. These separators have considerable advantages over filters, scrubbers or precipitators in term of compact design, lower pressure drop and higher capacity. A gas liquid centrifugal separator is a device that utilizes centrifugal forces and low pressure caused by rotational motion to separate liquid from gas by density differences. Efficient and reliable separation is required for the optimum operation. These separators are often operated at less than peak efficiency due to the entrainment of separated liquid through an outlet pipe which is closely associated with the very complicated flow phenomena involved. Design parameters such as length of the separation space, vane exit angle, inlet to outlet diameter ratio, models for separation efficiency and pressure drop as a function of physical dimensions are not available in literature. This leaves the designer with very little to go on except known designs and experimentation. The aim of present study is to perform a parametric study to get higher efficiency for gas-liquid separator. A parametric study has been carried out with the help of CFD tools to analyze a separation performance of a centrifugal separator by varying the length of separator space. The best design parameters are analyzed based upon obtained results, tangential velocities, vortices, total pressure losses. From the present study several attempts are made to improve the performance of conventional centrifugal separators.

Nagdewe, S.; Kwoon, J. K.; Kim, H. D.; Kim, D. S.; Kwak, K. M.; Setoguchi, Toshiaki

2008-09-01

295

Simulation of gas-liquid two-phase flow based on the Riemann problem  

NASA Astrophysics Data System (ADS)

This contribution report on recent scientific methodologies concerning compressible gas-liquid two-phase mixture. Within this context, a one-dimensional set of three partial differential equations that takes account of the velocity nonequilibrium between the two phases is used. Motivated by the hyperbolicity and conservativity features of these equations, a closed-form theoretical solution has provided key insights into the Riemann problem for the gas-liquid two-phase mixture. In addition to that, the proposed theoretical solution, that is an exact Riemann solver, calculates the entire wave structure including the middle states of the mixture and phases of the flow. To this end, the exact Riemann solver guarantees that the system of partial differential equations is independent of the type of the numerical technique used to validate it. Consequently, the model equations are solved numerically using Godunov methods of the upwind-type based upon the proposed exact Riemann solver. Sample academic simulations are performed and validated against analytical observations for the gas-liquid two-phase mixture. Through these simulations, we compare the predicted results with other numerical methods such as the Riemann-free solvers. Excellent agreement is observed between the analytical and numerical simulations.

Zeidan, D.; Touma, R.

2012-09-01

296

The analysis of carbohydrates in milk powder by a new "heart-cutting" two-dimensional liquid chromatography method.  

PubMed

In this study, a new"heart-cutting" two-dimensional liquid chromatography method for the simultaneous determination of carbohydrate contents in milk powder was presented. In this two dimensional liquid chromatography system, a Venusil XBP-C4 analysis column was used in the first dimension ((1)D) as a pre-separation column, a ZORBAX carbohydrates analysis column was used in the second dimension ((2)D) as a final-analysis column. The whole process was completed in less than 35min without a particular sample preparation procedure. The capability of the new two dimensional HPLC method was demonstrated in the determination of carbohydrates in various brands of milk powder samples. A conventional one dimensional chromatography method was also proposed. The two proposed methods were both validated in terms of linearity, limits of detection, accuracy and precision. The comparison between the results obtained with the two methods showed that the new and completely automated two dimensional liquid chromatography method is more suitable for milk powder sample because of its online cleanup effect involved. PMID:24412698

Ma, Jing; Hou, Xiaofang; Zhang, Bing; Wang, Yunan; He, Langchong

2014-03-01

297

Formation of iron complexs from trifluoroacetic acid based liquid chromatography mobile phases as interference ions in liquid chromatography/electrospray ionization mass spectrometric analysis  

SciTech Connect

Two unexpected singly charged ions at m/z 1103 and 944 have been observed in mass spectra obtained from electrospray ionization-mass spectrometric analysis of liquid chromatography effluents with mobile phases containing trifluoroacetic acid. Accurate mass measurement and tandem mass spectrometry studies revealed that these two ions are not due to any contamination from solvents and chemicals used for mobile and stationary phases or from the laboratory atmospheric environment. Instead these ions are clusters of trifluoroacetic acid formed in association with acetonitrile, water and iron from the stainless steel union used to connect the column with the electrospray tip and to apply high voltage; the molecular formulae are Fe+((OH)(H2O)2)9(CF3COOH)5 and Fe+((OH)(H2O)2)6 (CF3COOH)5.

Shukla, Anil K.; Zhang, Rui; Orton, Daniel J.; Zhao, Rui; Clauss, Therese RW; Moore, Ronald J.; Smith, Richard D.

2011-05-30

298

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.

299

Enantiomeric Separation in Comprehensive Two-dimensional Gas Chromatography with Accurate Mass Analysis.  

PubMed

Chiral comprehensive two-dimensional gas chromatography (eGC×GC) coupled to quadrupole-accurate mass time-of-flight mass spectrometry (QTOFMS) was evaluated for its capability to report the chiral composition of several monoterpenes, namely, ?-pinene, ?-pinene, and limonene in cardamom oil. Enantiomers in a standard mixture were fully resolved by direct enantiomeric-GC analysis with a 2,3-di-O-methyl-6-t-butylsilyl derivatized ?-cyclodextrin phase; however, the (+)-(R)-limonene enantiomer in cardamom oil was overlapped with other background components including cymene and cineole. Verification of (+)-(R)-limonene components based on characteristic ions at m/z 136, 121, and 107 acquired by chiral single-dimension GC-QTOFMS in the alternate MS/MSMS mode of operation was unsuccessful due to similar parent/daughter ions generated by interfering or co-eluting cymene and cineole. Column phases SUPELCOWAX, SLB-IL111, HP-88, and SLB-IL59, were incorporated as the second dimension column ((2) D) in chiral GC×GC analysis; the SLB-IL59 offered the best resolution for the tested monoterpene enantiomers from the matrix background. Enantiomeric ratios for ?-pinene, ?-pinene, and limonene were determined to be 1.325, 2.703, and 1.040, respectively, in the cardamom oil sample based on relative peak area data. Chirality 26:747-753, 2014. © 2014 Wiley Periodicals, Inc. PMID:24420979

Chin, Sung-Tong; Nolvachai, Yada; Marriott, Philip J

2014-11-01

300

Analysis of imazaquin in soybeans by solid-phase extraction and high-performance liquid chromatography.  

PubMed

An analytical method for the determination imazaquin residues in soybeans was developed. The developed liquid/liquid partition and strong anion exchange solid-phase extraction procedures provide the effective cleanup, removing the greatest number of sample matrix interferences. By optimizing mobile-phase pH water/acetonitrile conditions with phosphoric acid, using a C-18 reverse-phase chromatographic column and employing ultraviolet detection, excellent peak resolution was achieved. The combined cleanup and chromatographic method steps reported herein were sensitive and reliable for determining the imazaquin residues in soybean samples. This method is characterized by recovery >88.4%, precision <6.7% CV, and sensitivity of 0.005 ppm, in agreement with directives for method validation in residue analysis. Imazaquin residues in soybeans were further confirmed by high performance liquid chromatography-mass spectrometry (LC-MS). The proposed method was successfully applied to the analysis of imazaquin residues in soybean samples grown in an experimental field after treatments of imazaquin formulation. PMID:18183337

Guo, C; Hu, J-Y; Chen, X-Y; Li, J-Z

2008-02-01

301

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

302

Trace analysis of sulfamethazine in animal feed, human urine, and wastewater by electron capture gas chromatography  

SciTech Connect

Sulfamethazine, a widely used antibacterial drug additive in feeds for swine, chickens, and cattle, was scheduled for toxicological evaluation because of potential human health hazards associated with its residues in edible animal tissues. Analytical chemical procedures that would ensure proper concentration, homogeneity, and stability of the drug in dosed feed and its safe usage during the animal studies were prerequisites for such toxicological tests. Electron capture gas chromatographic (EC/GC) methods were therefore devised for the analysis of sulfamethazine residues in animal feed, human urine, and wastewater at levels as low as 100, 10, and 10 ppb, respectively. Sample extracts were cleaned up by using liquid/liquid partitioning, and the extracts were subjected to two derivatizations followed by cleanup on a silica gel column. The derivatizations of sulfamethazine consisted of methylation followed by trifluoroacetylation of the primary amine function. Ancillary data concerning stability of the compound in animal feed, water, and as a dry residue on glass, extraction efficiencies, partition values with various solvents, and the analysis of residues in feed by high pressure liquid chromatography (HPLC) at levels as low as 1.0 ppm are presented.

Holder, C.L.; Thompson, H.C. Jr.; Bowman, M.C.

1981-12-01

303

Trace analysis of sulfamethazine in animal feed, human urine, and wastewater by electron capture gas chromatography.  

PubMed

Sulfamethazine, a widely used antibacterial drug additive in feeds for swine, chickens, and cattle, was scheduled for toxicological evaluation because of potential human health hazards associated with its residues in edible animal tissues. Analytical chemical procedures that would ensure proper concentration, homogeneity, and stability of the drug in dosed feed and its safe usage during the animal studies were prerequisites for such toxicological tests. Electron capture gas chromatographic (EC/GC) methods were therefore devised for the analysis of sulfamethazine residues in animal feed, human urine, and wastewater at levels as low as 100, 10, and 10 ppb, respectively. Sample extracts were cleaned up by using liquid/liquid partitioning, and the extracts were subjected to two derivatizations followed by cleanup on a silica gel column. The derivatizations of sulfamethazine consisted of methylation followed by trifluoroacetylation of the primary amine function. Ancillary data concerning stability of the compound in animal feed, water, and as a dry residue on glass, extraction efficiencies, partition values with various solvents, and the analysis of residues in feed by high pressure liquid chromatography (HPLC) at levels as low as 1.0 ppm are presented. PMID:7328159

Holder, C L; Thompson, H C; Bowman, M C

1981-12-01

304

Ultra performance liquid chromatography tandem mass spectrometry performance evaluation for analysis of antibiotics in natural waters.  

PubMed

An ultra performance liquid chromatography electrospray tandem mass spectrometry (UPLC/MS/MS) method was developed and validated for the determination of 17 antibiotics in natural waters in one single extraction and chromatographic procedure. Gradient separation conditions were optimised for 17 compounds belonging to five different antibiotic groups: quinolones (oxolinic acid, nalidixic acid, pipemidic acid, flumequine), fluoroquinolones (enoxacin, ciprofloxacin, norfloxacin, ofloxacin, enrofloxacin, sarafloxacin, danofloxacin, difloxacin, lomefloxacin), sulphonamides (sulphamethoxazole, sulphamethazine), nitro-imidazole (ornidazole) and diaminopyrimidine (trimethoprim). The separation of all compounds, obtained using a 1.7 microm particle size column (100 mm x 2.1 mm), was achieved within 10 min time. Water samples were adjusted to pH 7 and extracted using Oasis hydrophilic-lipophilic balance (HLB) solid phase extraction cartridges. After elution with methanol and concentration, extracts were injected in a C18 column (Acquity UPLC BEH C18) and detected by tandem mass spectrometry. Average recovery from 100 ng L(-1) fortified samples was higher than 70% for most of the compounds, with relative standard deviations below 20%. Performances of the method (recoveries, detection limit, quantification limit and relative standard deviation) and matrix effects were studied, and results obtained showed that method was suitable for routine analysis of antibiotics in surface water. Samples analysis from Seine River (France) confirmed the interest of antibiotic contamination evaluation in that area. PMID:19148627

Tamtam, Fatima; Mercier, Fabien; Eurin, Joëlle; Chevreuil, Marc; Le Bot, Barbara

2009-03-01

305

The analysis of forensic samples using laser micro-pyrolysis gas chromatography mass spectrometry.  

PubMed

Laser micropyrolysis gas chromatography-mass spectrometry is used for the analysis of paint, photocopier toner, and synthetic fiber materials to test the forensic potential of this emerging technology. It uses a laser microprobe to selectively target very small parts of the materials for GC-MS analysis. Whereas the paint and the toner samples were amenable to direct laser pyrolysis, the synthetic fibers proved transparent to the 1064 nm laser radiation. The difficulty with the fibers demonstrates that a specific laser wavelength may not be appropriate for all types of materials. Nevertheless, the fibers were able to be indirectly pyrolyzed by impregnation in a strongly absorbing graphite matrix. A vast array of hydrocarbon pyrolysates was detected from the different materials studied. Unique product distributions were detected from each sample and in sufficient detail to facilitate individual molecular characterization (i.e., molecular fingerprinting). The integrity of the laser data were confirmed by comparison to data obtained from the same samples by the more conventional pyroprobe pyrolysis GC-MS method. The high spatial resolution and selectivity of the laser method may be advantageous for specific forensic applications, however, further work may be required to improve the reproducibility of the data. PMID:11569542

Armitage, S; Saywell, S; Roux, C; Lennard, C; Greenwood, P

2001-09-01

306

Analysis of antithyroid drugs in surface water by using liquid chromatography-tandem mass spectrometry.  

PubMed

This paper describes development and validation of a new method for the simultaneous determination of six antithyroid drugs (ATDs) in surface waters by using liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS). Target compounds include two ATD classes: thiouracil derivatives (thiouracil (TU), methyl-thiouracil (MTU), propyl-thiouracil (PTU), phenyl-thiouracil (PhTU)) and imidazole derivatives (tapazole (TAP), and mercaptobenzimidazole (MBI)). Sensitivity and selectivity of the LC-multiple reaction monitoring (MRM) analysis allowed applying a simple pre-concentration procedure and "shooting" the concentrated sample into the LC-MS/MS system without any other treatment. Recoveries were higher than 75% for all analytes. Intra-day precision and inter-day precision, calculated as relative standard deviation (RSD), were below 19 and 22%, respectively. Limits of detection (LODs) ranged from 0.05 to 0.25?g/L; limits of quantitation (LOQs) varied between 0.15 and 0.75?g/L. The validated method was successfully applied to the analysis of ATD residues in surface water samples collected from the Tiber River basin and three lakes of Lazio (central Italy). The analytes were quantified based on matrix-matched calibration curves with mercaptobenzimidazole-d4 (MBI-d4) as the internal standard (IS). The most widespread compound was TAP, one of the most common ATDs used in human medicine, but also TU and MBI were often detected in the analysed samples. PMID:25287266

Pérez-Fernández, Virginia; Marchese, Stefano; Gentili, Alessandra; García, María Ángeles; Curini, Roberta; Caretti, Fulvia; Perret, Daniela

2014-11-01

307

Hyphenation of optimized microfluidic sample preparation with nano liquid chromatography for faster and greener alkaloid analysis.  

PubMed

A glass liquid-liquid extraction (LLE) microchip with three parallel 3.5 cm long and 100 ?m wide interconnecting channels was optimized in terms of more environmentally friendly (greener) solvents and extraction efficiency. In addition, the optimized chip was successfully hyphenated with nano-liquid chromatography with ultraviolet and mass spectrometric detection (nanoLC-UV-MS) for on-line analysis. In this system, sample pretreatment, separation and detection are integrated, which significantly shortens the analysis time, saves labor and drastically reduces solvent consumption. Strychnine was used as model analyte to determine the extraction efficiency of the optimized 3-phase chip. Influence of organic solvent, pH of feed phase, type of alkaloid, and flow rates were investigated. The results demonstrated that the 3-phase chip nanoLC-UV/MS hyphenation combines rapid (~25 s) and efficient (extraction efficiency >90%) sample prep, with automated alkaloid analyses. The method was applied to real samples including Strychnos nux-vomica seeds, Cephaelis ipecacuanha roots, Atropa belladonna leaves, and Vinca minor leaves. PMID:24050669

Shen, Yao; van Beek, Teris A; Zuilhof, Han; Chen, Bo

2013-10-01

308

ANALYSIS OF DRUG INTERACTIONS WITH HIGH DENSITY LIPOPROTEIN BY HIGH-PERFORMANCE AFFINITY CHROMATOGRAPHY  

PubMed Central

Columns containing immobilized lipoproteins were prepared for the analysis of drug interactions with these particles by high-performance affinity chromatography. This approach was evaluated by using it to examine the binding of high density lipoprotein (HDL) to the drugs propranolol or verapamil. HDL was immobilized by the Schiff base method onto silica and gave HPLC columns with reproducible binding to propranolol over four to five days of continuous operation at pH 7.4. Frontal analysis experiments indicated that two types of interactions were occurring between R/S-propranolol and HDL at 37°C: saturable binding with an association equilibrium constant (Ka) of 1.1–1.9 × 105 M?1, and non-saturable binding with an overall affinity constant (n Ka) of 3.7–4.1 × 104 M?1. Similar results were found at 4 and 27°C. Verapamil also gave similar behavior, with a Ka of 6.0 × 104 M?1 at 37°C for the saturable sites and a n Ka value for the non-saturable sites of 2.5 × 104 M?1. These measured affinities gave good agreement with solution-phase values. The results indicated HPAC can be used to study drug interactions with HDL, providing information that should be valuable in obtaining a better description of how drugs are transported within the body. PMID:19833090

Chen, Sike; Sobansky, Matthew R.; Hage, David S.

2009-01-01

309

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

310

[Analysis of aliphatic carboxylic acids in anaerobic digestion process waters by ion-exclusion chromatography].  

PubMed

The analysis of seven aliphatic carboxylic acids (formic, acetic, propionic, iso-butyric, n-butyric, iso-valeric and n-valeric acid) in anaerobic digestion process waters for biogas production was examined by ion-exclusion chromatography with dilute acidic eluents (benzoic acid, perfluorobutyric acid (PFBA) and sulfuric acid) and non-suppressed conductivity/ultraviolet (UV) detection. The columns used were a styrene/divinylbenzene-based strongly acidic cation-exchange resin column (TSKgel SCX) and a polymethacrylate-based weakly acidic cation-exchange resin column (TSKgel Super IC-A/C). Good separation was performed on the TSKgel SCX in shorter retention times. For the TSKgel Super IC-A/C, peak shape of the acids was sharp and symmetrical in spite of longer retention times. In addition, the mutual separation of the acids was good except for iso- and n-butyric acids. The better separation and good detection was achieved by using the two columns (TSKgel SCX and TSKgel Super IC-A/C connected in series), lower concentrations of PFBA and sulfuric acid as eluents, non-suppressed conductivity detection and UV detection at 210 nm. This analysis was applied to anaerobic digestion process waters. The chromatograms with conductivity detection were relatively simpler compared with those of UV detection. The use of two columns with different selectivities for the aliphatic carboxylic acids and the two detection modes was effective for the determination and identification of the analytes in anaerobic digestion process waters containing complex matrices. PMID:22799193

Ito, Kazuaki; Sakamoto, Jun; Nagaoka, Kazuya; Takayama, Yohichi; Kanahori, Takashi; Sunahara, Hiroshi; Hayashi, Tsuneo; Sato, Shinji; Hirokawa, Takeshi; Tanaka, Kazuhiko

2012-04-01

311

Quantitative analysis of heterocyclic amines in urine by liquid chromatography coupled with tandem mass spectrometry.  

PubMed

A sensitive, reproducible, and rapid analytical method for the analysis of trace-level heterocyclic amines (HCAs) that are expected to have high levels of human exposure was developed. Liquid-liquid extraction (LLE) with dichloromethane (DCM) followed by solid-phase extraction (SPE) was carried out. Liquid extraction with DCM under basic conditions was efficient in extracting HCAs from urine samples. For further purification, mixed mode cationic exchange (MCX) cartridges were applied to eliminate the remaining interferences after liquid extraction. Separation and quantification were performed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) in selected reaction monitoring (SRM) mode. The overall recoveries ranged between 71.0% and 113.6% with relative standard deviations (RSDs) of 5.1% to 14.7% for the entire procedure. The limits of detection (LODs) and limits of quantification (LOQs) of the proposed analytical method were in the ranges of 0.04 to 0.10 ng/ml and 0.15 to 0.36 ng/ml, respectively. This method was applied to the analysis of monitoring in urine samples for Korean school children, and the results demonstrated that the method can be used for the trace determination of HCAs in urine samples. PMID:24269709

Shin, Jeoung Hwa; Na, Yun-Cheol; Chung, Joo Hee; Gorinstein, Shela; Ahn, Yun Gyong

2014-02-15

312

On-line analysis of volatile organics in water using head space gas chromatography: evaluation of five head space techniques  

Microsoft Academic Search

Many industrial effluent streams require monitoring for volatile organic carbon (VOC) at part per billion concentration levels. Head-space gas chromatography (GC) is a suitable on-line technique for this analysis (the VOCs are stripped from the water prior to analysis by GC). This paper evaluates five dynamic head-space systems for sensitivity, linearity, response time and simplicity. One of the head-space systems

Don Schieck; Fred Brown

1996-01-01

313

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

314

Transport evaluation of a gas-liquid scrubber. [Five-tray, single-bubble-cap, single-downcomer, gas liquid contactor  

SciTech Connect

The hydraulics and the mass-transfer behavior of a five-tray, single-bubble-cap, single-downcomer, gas-liquid contactor were studied for use as a gas scrubber. Flooding was not observed at the maximum available liquid and gas flow rates of 0.32 and 464 L/min, respectively. The maximum liquid entrainment was 33% at a gross liquid flow rate of 0.05 L/min. The Murphree-tray efficiencies for absorption of CO/sub 2/ (5000 ppM in air) into demineralized water ranged from 0.14 to 0.74 for volumetric liquid-to-gas ratios of 4 x 10/sup -4/ and 2 x 10/sup -4/, respectively, for k/sub L/a values ranging from 0.088 to 0.36 min/sup -1/. 12 figures, 10 tables.

Brodner, A.J.; Bistline, J.E.; Weber, S.E.

1982-10-01

315

Applying Chromatography.  

ERIC Educational Resources Information Center

Presents three experiments to introduce students to different kinds of chromatography: (1) paper chromatography; (2) gel filtration chromatography; and (3) reverse-phase liquid chromatography. Written in the form of a laboratory manual, explanations of each of the techniques, materials needed, procedures, and a glossary are included. (PVD)

Klein, Jessie W.; Patev, Paul

1998-01-01

316

Analysis of endocrine disrupters and related compounds in sediments and sewage sludge using on-line turbulent flow chromatography-liquid chromatography-tandem mass spectrometry.  

PubMed

A novel fully automated method based on dual column switching using turbulent flow chromatography followed by liquid chromatography coupled to tandem mass spectrometry (TFC-LC-MS/MS) was applied for the determination of endocrine disruptors (EDCs) and related compounds in sediment and sewage sludge samples. This method allows the unequivocal identification and quantification of the most relevant environmental EDCs such as natural and synthetic estrogens and their conjugates, antimicrobials, parabens, bisphenol A (BPA), alkylphenolic compounds, benzotriazoles, and organophosphorus flame retardants, minimizing time of analysis and alleviating matrix effects. Applying this technique, after the extraction of the target compounds by pressurized liquid extraction (PLE), sediment and sewage sludge extracts were directly injected to the chromatographic system and the analytes were concentrated into the clean-up loading column. Using six-port switching system, the analytes were transferred to the analytical column for subsequent detection by MS-MS (QqQ). In order to optimize this multiplexing system, a comparative study employing six types of TurboFlow™ columns, with different chemical modifications, was performed to achieve the maximum retention of analytes and best elimination of matrix components. Using the optimized protocol low limits of quantification (LOQs) were obtained ranging from 0.0083 to 1.6 ng/g for sediment samples and from 0.10 to 125 ng/g for sewage sludge samples (except for alkylphenol monoethoxylate). The method was used to evaluate the presence and fate of target EDCs in the Ebro River which is the most important river in Spain with intensive agricultural and industrial activities in the basin that contribute to deteriorating soil and water quality. PMID:24909438

Gorga, Marina; Insa, Sara; Petrovic, Mira; Barceló, Damià

2014-07-25

317

A rapid analysis of plasma/serum ethylene and propylene glycol by headspace gas chromatography.  

PubMed

A rapid headspace-gas chromatography (HS-GC) method was developed for the analysis of ethylene glycol and propylene glycol in plasma and serum specimens using 1,3-propanediol as the internal standard. The method employed a single-step derivitization using phenylboronic acid, was linear to 200 mg/dL and had a lower limit of quantitation of 1 mg/dL suitable for clinical analyses. The analytical method described allows for laboratories with HS-GC instrumentation to analyze ethanol, methanol, isopropanol, ethylene glycol, and propylene glycol on a single instrument with rapid switch-over from alcohols to glycols analysis. In addition to the novel HS-GC method, a retrospective analysis of patient specimens containing ethylene glycol and propylene glycol was also described. A total of 36 patients ingested ethylene glycol, including 3 patients who presented with two separate admissions for ethylene glycol toxicity. Laboratory studies on presentation to hospital for these patients showed both osmolal and anion gap in 13 patients, osmolal but not anion gap in 13 patients, anion but not osmolal gap in 8 patients, and 1 patient with neither an osmolal nor anion gap. Acidosis on arterial blood gas was present in 13 cases. Only one fatality was seen; this was a patient with initial serum ethylene glycol concentration of 1282 mg/dL who died on third day of hospitalization. Propylene glycol was common in patients being managed for toxic ingestions, and was often attributed to iatrogenic administration of propylene glycol-containing medications such as activated charcoal and intravenous lorazepam. In six patients, propylene glycol contributed to an abnormally high osmolal gap. The common presence of propylene glycol in hospitalized patients emphasizes the importance of being able to identify both ethylene glycol and propylene glycol by chromatographic methods. PMID:23741644

Ehlers, Alexandra; Morris, Cory; Krasowski, Matthew D

2013-12-01

318

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 ...

319

Sources of Variability in Chlorophyll Analysis by Fluorometry and by High Performance Liquid Chromatography. Chapter 22  

NASA Technical Reports Server (NTRS)

The need for accurate determination of chlorophyll a (chl a) is of interest for numerous reasons. From the need for ground-truth data for remote sensing to pigment detection for laboratory experimentation, it is essential to know the accuracy of the analyses and the factors potentially contributing to variability and error. Numerous methods and instrument techniques are currently employed in the analyses of chl a. These methods range from spectrophotometric quantification, to fluorometric analysis and determination by high performance liquid chromatography. Even within the application of HPLC techniques, methods vary. Here we provide the results of a comparison among methods and provide some guidance for improving the accuracy of these analyses. These results are based on a round-robin conducted among numerous investigators, including several in the Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) and HyCODE Programs. Our purpose here is not to present the full results of the laboratory intercalibration; those results will be presented elsewhere. Rather, here we highlight some of the major factors that may contribute to the variability observed. Specifically, we aim to assess the comparability of chl a analyses performed by fluorometry and HPLC, and we identify several factors in the analyses which may contribute disproportionately to this variability.

VanHeukelem, Laurie; Thomas, Crystal S.; Glibert, Patricia M.

2001-01-01

320

Analysis of Dyes Extracted from Millimeter-Size Nylon Fibers by Micellar Electrokinetic Chromatography  

SciTech Connect

The Learning Objective is to present to the forensic community a potential qualitative/quantitative method for trace-fiber color comparisons using micellar electrokinetic chromatography (MEKC). Developing a means of analyzing extracted dye constituents from millimeter-size nylon fiber samples was the objective of this research initiative. Aside from ascertaining fiber type, color evaluation and source comparison of trace-fiber evidence plays a critical role in forensic-fiber examinations. Literally thousands of dyes exist to date, including both natural and synthetic compounds. Typically a three-color-dye combination is employed to affect a given color on fiber material. The result of this practice leads to a significant number of potential dye combinations capable of producing a similar color and shade. Since a typical forensic fiber sample is 2 mm or less in length, an ideal forensic dye analysis would qualitatively and quantitatively identify the extracted dye constituents from a sample size of 1 mm or smaller. The goal of this research was to develop an analytical method for comparing individual dye constituents from trace-fiber evidence with dyes extracted from a suspected source, while preserving as much of the original evidence as possible.

Lewis, L.A.

2001-07-30

321

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

322

Analysis of Fluconazole in Human Urine Sample by High Performance Liquid Chromatography Method  

NASA Astrophysics Data System (ADS)

A method for determination of fluconazole, antifungal drug in human urine by using reversed-phased high performance liquid chromatography (RP-HPLC) with ultraviolet (UV) detector was developed. Optimization HPLC conditions were carried out by changing the flow rate and composition of mobile phase. The optimum separation conditions at a flow rate 0.85 mL/min with a composition of mobile phase containing methanol:water (70:30, v/v) with UV detection at a wavelength 254 nm was able to analyze fluconazole within 3 min. The excellent linearity was obtained in the range of concentration 1 to 10 ?g/mL with r2 = 0.998. The limit of detection (LOD) and limit of quantitation (LOQ) were 0.39 ?g/mL and 1.28 ?g/mL, respectively. Solid phase extraction (SPE) method using octadecylsilane (C18) as a sorbent was used to clean-up and pre-concentrated of the urine sample prior to HPLC analysis. The average recoveries of fluconazole in spiked urine sample was 72.4% with RSD of 3.21% (n=3).

Hermawan, D.; Ali, N. A. Md; Ibrahim, W. A. Wan; Sanagi, M. M.

2013-04-01

323

Separation and analysis of 4'-epimeric UDP-sugars by borate high-performance liquid chromatography.  

PubMed

Separation of UDP-glucose from UDP-galactose, of UDP-N-acetylglucosamine from UDP-N-acetylgalactosamine, of UDP-glucuronate from UDP-galacturonate, or of UDP-glucosamine from UDP-galactosamine was achieved within 10-45 min by isocratic anion-exchange high-performance liquid chromatography (HPLC) using a flow rate of 2 ml/min. The eluants were composed of borate as complex-forming and eluting agent and of glycerol for protection of the alkali-labile silica packing of the column. This borate HPLC was suitable for the analysis of 4'-epimeric UDP-sugars in the range of 2 to 100 nmol. The applicability of this technique was demonstrated by determination of the relative amounts of 4'-epimeric UDP-amino sugars formed in rat liver after administration of D-galactosamine. Since a high salt content of UDP-sugar samples can interfere with borate HPLC, desalting was performed on a 1-ml C18 cartridge using triethylammonium hydrogen carbonate buffer. This procedure enabled the complete separation of various nucleotides from salts within 10 min prior to HPLC. PMID:6625174

Weckbecker, G; Keppler, D O

1983-07-15

324

ENVIRONMENTAL ANALYSIS BY AB INITIO QUANTUM MECHANICAL COMPUTATION AND GAS CHROMATOGRAPHY/FOURIER TRANSFORM INFRARED SPECTROMETRY.  

EPA Science Inventory

Computational chemistry, in conjunction with gas chromatography/mass spectrometry/Fourier transform infrared spectrometry (GC/MS/FT-IR), was used to tentatively identify seven tetrachlorobutadiene (TCBD) isomers detected in an environmental sample. Computation of the TCBD infrare...

325

Analysis of glycoprotein oligosaccharides using high-pH anion exchange chromatography.  

PubMed

The natural heterogeneity of glycoprotein glycans requires that chromatography be an essential part of structural elucidation. The isomeric nature of oligosaccharide structure requires chromatography which is selective for not only composition, size and anomerity, but also ring substitutions and branching configurations. HPAEC is sensitive to these structural features and thus, has become an important new method for understanding the elusive function of glycoprotein glycans. PMID:1823157

Townsend, R R; Hardy, M R

1991-03-01

326

[Purification of plastocynin from Ulva pertusa by column chromatography and analysis of its N-terminal amino acid sequence].  

PubMed

Protein plastocyanin from a green alga, Ulva pertusa, has been purified. Samples were homogenized in 0.02 mol/L phosphate buffer (pH 7.2) and then centrifuged to remove debris and subjected to ammonium sulfate fractionation (40%-80% saturation). Ion exchange column chromatography with DEAE-Sepharose Fast Flow and gel filtration column chromatography with Sephadex G-75 were then employed for further purification of plastocyanin. Three peaks, A, B and C, were eluted with 0.01 mol/L phosphate buffer, containing a NaCl linear gradient from 0 to 1.0 mol/L at the flow rate of 32 mL/h through DEAE-Sepharose chromatography. The protein fractions containing the plastocyanin were then purified further with Sephardex G-75 column chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophores (SDS-PAGE) is analysis indicates that the protein was purified to homogeneity and its relative molecular mass is 10,000. N-terminal amino acid sequence was used to identify the protein. The protein was transblotted to PVDF membrane and N-terminal amino acid sequence was performed via Edman degradation with an automated amino acid sequencer. The 20 N-terminal amino acid residues are AAIVKLGPDDGSLAFVPSKI, which share 85% homology with the 20 N-terminal amino acid sequence of U. prolifera and U. arasakii, and share 90% homology with the ones of U. pertusa formerly reported. PMID:16929848

Liu, Zhenyu; Wu, Zujian; Lin, Qiying; Xie, Lianhui

2006-05-01

327

Comprehensive analysis of pharmaceutical products using simultaneous mixed-mode (ion-exchange/reversed-phase) and hydrophilic interaction liquid chromatography.  

PubMed

Liquid chromatographic assays were developed using a mixed-mode column coupled in sequence with a hydrophilic interaction liquid chromatography column to allow the simultaneous comprehensive analysis of inorganic/organic anions and cations, active pharmaceutical ingredients, and excipients (carbohydrates). The approach utilized dual sample injection and valve-mediated column switching and was based upon a single high-performance liquid chromatography gradient pump. The separation consisted of three distinct sequential separation mechanisms, namely, (i) ion-exchange, (ii) mixed-mode interactions under an applied dual gradient (reversed-phase/ion-exchange), and (iii) hydrophilic interaction chromatography. Upon first injection, the Scherzo SS C18 column (Imtakt) provided resolution of inorganic anions and cations under isocratic conditions, followed by a dual organic/salt gradient to elute active pharmaceutical ingredients and their respective organic counterions and potential degradants. At the top of the mixed-mode gradient (high acetonitrile content), the mobile phase flow was switched to a preconditioned hydrophilic interaction liquid chromatography column, and the standard/sample was reinjected for the separation of hydrophilic carbohydrates, some of which are commonly known excipients in drug formulations. The approach afforded reproducible separation and resolution of up to 23 chemically diverse solutes in a single run. The method was applied to investigate the composition of commercial cough syrups (Robitussin®), allowing resolution and determination of inorganic ions, active pharmaceutical ingredients, excipients, and numerous well-resolved unknown peaks. PMID:24890905

Kazarian, Artaches A; Nesterenko, Pavel N; Soisungnoen, Phimpha; Burakham, Rodjana; Srijaranai, Supalax; Paull, Brett

2014-08-01

328

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

329

Amino acid analysis by using comprehensive two-dimensional gas chromatography.  

PubMed

The separation characteristics of alkylchloroformate-derivatised amino acids (AAs) by using comprehensive two-dimensional gas chromatography (GCxGC) is reported. The use of a low-polarity/polar column set did not provide as good a separation performance as that achieved with a polar/non-polar column set, where the latter appeared to provide less correlation over the separation space. The degree of component correlation in each column set was estimated by using the correlation coefficient (r(2); for (1)t(R) and (2)t(R) data) with the low-polarity/polar and polar/low-polarity sets returning correlation coefficients of 0.86, and 0.00 respectively, under the respective conditions employed for the experiments. The 1.5-m non-polar (2)D column (0.1-mm ID; 0.1-mum film thickness) gave peak halfwidths of the order of 50-80 ms. Linearity of detection was good, over a three order of magnitude concentration range, with typical lower detection limit of ca. 0.01 mg L(-1), compared with 0.5 mg L(-1) for normal GC operation with splitless injection. The method was demonstrated for analysis of AAs in a range of food and beverage products, including wine, beer and honey. The major AA in these samples was proline. The Heineken beer sample had a relatively more complex and more abundant AA content compared with the other beer sample. The wine and honey samples also gave a range of AA compounds. Repetition of the sample preparation/analysis procedure for the honey sample gave acceptable reproducibility for individual AAs. PMID:15838615

Mayadunne, Renuka; Nguyen, Thuy-Tien; Marriott, Philip J

2005-06-01

330

Perceptual Characterization and Analysis of Aroma Mixtures Using Gas Chromatography Recomposition-Olfactometry  

PubMed Central

This paper describes the design of a new instrumental technique, Gas Chromatography Recomposition-Olfactometry (GC-R), that adapts the reconstitution technique used in flavor chemistry studies by extracting volatiles from a sample by headspace solid-phase microextraction (SPME), separating the extract on a capillary GC column, and recombining individual compounds selectively as they elute off of the column into a mixture for sensory analysis (Figure 1). Using the chromatogram of a mixture as a map, the GC-R instrument allows the operator to “cut apart" and recombine the components of the mixture at will, selecting compounds, peaks, or sections based on retention time to include or exclude in a reconstitution for sensory analysis. Selective recombination is accomplished with the installation of a Deans Switch directly in-line with the column, which directs compounds either to waste or to a cryotrap at the operator's discretion. This enables the creation of, for example, aroma reconstitutions incorporating all of the volatiles in a sample, including instrumentally undetectable compounds as well those present at concentrations below sensory thresholds, thus correcting for the “reconstitution discrepancy" sometimes noted in flavor chemistry studies. Using only flowering lavender (Lavandula angustifola ‘Hidcote Blue’) as a source for volatiles, we used the instrument to build mixtures of subsets of lavender volatiles in-instrument and characterized their aroma qualities with a sensory panel. We showed evidence of additive, masking, and synergistic effects in these mixtures and of “lavender' aroma character as an emergent property of specific mixtures. This was accomplished without the need for chemical standards, reductive aroma models, or calculation of Odor Activity Values, and is broadly applicable to any aroma or flavor. PMID:22912722

Johnson, Arielle J.; Hirson, Gregory D.; Ebeler, Susan E.

2012-01-01

331

Liquid chromatography-tandem mass spectrometry for the analysis of eicosanoids and related lipids in human biological matrices: a review.  

PubMed

Today, there is an increasing number of liquid chromatography tandem-mass spectrometric (LC-MS/MS) methods for the analysis of eicosanoids and related lipids in biological matrices. An overview of currently applied LC-MS/MS methods is given with attention to sample preparation strategies, chromatographic separation including ultra high performance liquid chromatography (UHPLC) and chiral separation, as well as to mass spectrometric detection using multiple reacting monitoring (MRM). Further, the application in recent clinical research is reviewed with focus on preanalytical aspects prior to LC-MS/MS analysis as well as applications in major diseases of Western civilization including respiratory diseases, diabetes, cancer, liver diseases, atherosclerosis, and neurovascular diseases. PMID:24583205

Kortz, Linda; Dorow, Juliane; Ceglarek, Uta

2014-08-01

332

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

333

Comparison of high-performance liquid chromatography and spectrofluorimetry for vitamin C analysis of green beans ( Phaseolus vulgaris L.)  

Microsoft Academic Search

A spectrofluorimetric method and a chromatographic method [high-performance liquid chromatography – ultraviolet (HPLC-UV)\\u000a detection] were compared for vitamin C analysis of green beans. For HPLC-UV, the determination was performed before [ascorbic\\u000a acid (AA)] and after reduction with dithiothreitol [AA + dehydroascorbic acid (DHAA)]; for spectrofluorimetry, DHAA was determined\\u000a after oxidation with activated charcoal. The fluorimetric determination of DHAA before oxidation

Maria Cortes Sánchez-Mata; Montaña Cámara-Hurtado; Carmen Díez-Marqués; Maria Esperanza Torija-Isasa

2000-01-01

334

Analysis of acidic drugs in the effluents of sewage treatment plants using liquid chromatography–electrospray ionization tandem mass spectrometry  

Microsoft Academic Search

A liquid chromatography–electrospray ionization tandem mass spectrometry (LC–ESI-MS–MS) method was developed and validated for simultaneous analysis of nine acidic pharmaceutical drugs (bezafibrate, clofibric acid, diclofenac, fenoprofen, gemfibrozil, ibuprofen, indomethacin, ketoprofen and naproxen) in sewage treatment plant (STP) effluents. The mean recoveries of the pharmaceuticals ranged from 58.9 to 91.5% in STP effluent, and the limits of detection of the analytes

Xiu-Sheng Miao; Brenda G Koenig; Chris D Metcalfe

2002-01-01

335

Evaluation of gas chromatography columns for the analysis of the 15 + 1 EU-priority polycyclic aromatic hydrocarbons (PAHs)  

Microsoft Academic Search

Three different stationary phases were investigated for the analysis of the 15 + 1 EU-priority polycyclic aromatic hydrocarbons\\u000a (PAHs) by gas chromatography-mass spectrometry. In addition to the most commonly used 5% phenyl methylpolysiloxane, a mid-polar\\u000a phase (50% phenyl methylpolysiloxane) and a recently commercialised mid-polar to polar phase (Optima® ?-6), were evaluated.\\u000a Challenging groups of PAHs in terms of separation, such

José Ángel Gómez-Ruiz; Thomas Wenzl

2009-01-01

336

Numerical simulations of gas-liquid flow in the gas injection process with mechanical stirring  

NASA Astrophysics Data System (ADS)

Based on Euler-Euler approach, a mathematical model is established to describe gas and liquid two-phase flow in a gas injected mechanically stirred system used in hot metal desulfurization process. The influences of different impellers types and rotation methods were investigated. The results show that the predicted distribution of bubbles in the bath agrees well with experimental results. The gas-liquid flow in the gas injected-mechanically stirred system can be accurately described by the present model. Compared to the standard impeller, the improved impeller in forward stirring mode is more efficient to increase the retention time and dispersion of bubbles.

Shao, Pin; Zhang, Ting'an; Liu, Yan; Zhang, Zimu; Wang, Dongxing

2013-06-01

337

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

338

Rapid Decomposition of Cellulose Dissolved in Ionic Liquid Using Gas-Liquid Interface Discharge  

NASA Astrophysics Data System (ADS)

Cellulose was dissolved at 3 wt % in 15 mL of 1-allyl-3-methylimidazolium chloride ([Amim]Cl) together with 2 wt % water, and then gas-liquid interface discharge was carried out at 20 W for 200 s. As a result, 7.6% of initially dissolved cellulose decomposed and 3.9% of initially dissolved cellulose changed into reducing sugar. Adding a small amount of water to the solution was essential for the decomposition of cellulose. [Amim]Cl was stable against the discharge, as determined from the NMR signals measured before and after the discharge.

Furukawa, Shoichiro; Inoue, Nobuhiro; Ishioka, Toshio; Furuya, Kenji; Harata, Akira

2012-07-01

339

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

340

On the Motion of an Annular Film in Microgravity Gas-Liquid Flow  

NASA Technical Reports Server (NTRS)

Three flow regimes have been identified for gas-liquid flow in a microgravity environment: Bubble, Slug, and Annular. For the slug and annular flow regimes, the behavior observed in vertical upflow in normal gravity is similar to microgravity flow with a thin, symmetrical annular film wetting the tube wall. However, the motion and behavior of this film is significantly different between the normal and low gravity cases. Specifically, the liquid film will slow and come to a stop during low frequency wave motion or slugging. In normal gravity vertical upflow, the film has been observed to slow, stop, and actually reverse direction until it meets the next slug or wave.

McQuillen, John B.

2002-01-01

341

Probing the microscopic corrugation of liquid surfaces with gas-liquid collisions  

NASA Technical Reports Server (NTRS)

We have measured the directions and velocities of Ne, Ar, and Xe atoms scattering from perfluorinated ether and hydrocarbon liquids to probe the relationship between the microscopic roughness of liquid surfaces and gas-liquid collision dynamics. Impulsive energy transfer is governed by the angle of deflection: head-on encounters deposit more energy than grazing collisions. Many atoms scatter in the forward direction, particularly at glancing incidence. These results imply that the incoming atoms recoil locally from protruding C-H and C-F groups in hard spherelike collisions.

King, Mackenzie E.; Nathanson, Gilbert M.; Hanning-Lee, Mark A.; Minton, Timothy K.

1993-01-01

342

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

343

Generalization of low pressure, gas-liquid, metastable sound speed to high pressures  

NASA Technical Reports Server (NTRS)

A theory is developed for isentropic metastable sound propagation in high pressure gas-liquid mixtures. Without simplification, it also correctly predicts the minimum speed for low pressure air-water measurements where other authors are forced to postulate isothermal propagation. This is accomplished by a mixture heat capacity ratio which automatically adjusts from its single phase values to approximately the isothermal value of unity needed for the minimum speed. Computations are made for the pure components parahydrogen and nitrogen, with emphasis on the latter. With simplifying assumptions, the theory reduces to a well known approximate formula limited to low pressure.

Bursik, J. W.; Hall, R. M.

1981-01-01

344

Ground Based Studies of Gas-Liquid Flows in Microgravity Using Learjet Trajectories  

NASA Technical Reports Server (NTRS)

A 1.27 cm diameter two phase gas-liquid flow experiment has been developed with the NASA Lewis Research Center to study two-phase flows in microgravity. The experiment allows for the measurement of void fraction, pressure drop, film thickness and bubble and wave velocities as well as for high speed photography. Three liquids were used to study the effects of liquid viscosity and surface tension, and flow pattern maps are presented for each. The experimental results are used to develop mechanistically based models to predict void fraction, bubble velocity, pressure drop and flow pattern transitions in microgravity.

Bousman, W. S.; Dukler, A. E.

1994-01-01

345

Gas liquid flow at microgravity conditions - Flow patterns and their transitions  

NASA Technical Reports Server (NTRS)

The prediction of flow patterns during gas-liquid flow in conduits is central to the modern approach for modeling two phase flow and heat transfer. The mechanisms of transition are reasonably well understood for flow in pipes on earth where it has been shown that body forces largely control the behavior observed. This work explores the patterns which exist under conditions of microgravity when these body forces are suppressed. Data are presented which were obtained for air-water flow in tubes during drop tower experiments and Learjet trajectories. Preliminary models to explain the observed flow pattern map are evolved.

Dukler, A. E.; Fabre, J. A.; Mcquillen, J. B.; Vernon, R.

1987-01-01

346

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

347

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

348

Novel Finite Difference Lattice Boltzmann Model for Gas-Liquid Flow  

NASA Astrophysics Data System (ADS)

A novel model for the finite difference lattice Boltzmann method is proposed to simulate gas-liquid two-phase flow. The effect of the large density difference is incorporated by applying acceleration modification which is deduced from macroscopic dynamics in this model. Compressibility of the fluid is adjustable. Surface tension effects are included by introducing a body force term based on the Continuum Surface Force (CSF) method. The recoloring step is replaced by a anti-diffusion scheme. Here we present results for liquid column collapse and droplet splashing on a thin liquid film. Results are in good agreement with experiment.

Wu, Long; Tsutahara, Michihisa; Tajiri, Shinsuke

2008-02-01

349

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

350

Targeted three-dimensional liquid chromatography: a versatile tool for quantitative trace analysis in complex matrices.  

PubMed

Targeted multidimensional liquid chromatography (MDLC), commonly referred to as 'coupled-column' or 'heartcutting', has been used extensively since the 1970s for analysis of low concentration constituents in complex biological and environmental samples. A primary benefit of adding additional dimensions of separation to conventional HPLC separations is that the additional resolving power provided by the added dimensions can greatly simplify method development for complex samples. Despite the long history of targeted MDLC, nearly all published reports involve two-dimensional methods, and very few have explored the benefits of adding a third dimension of separation. In this work we capitalize on recent advances in reversed-phase HPLC to construct a three-dimensional HPLC system for targeted analysis built on three very different reversed-phase columns. Using statistical peak overlap theory and one of the most recent models of reversed-phase selectivity we use simulations to show the potential benefit of adding a third dimension to a MDLC system. We then demonstrate this advantage experimentally by developing targeted methods for the analysis of a variety of broadly relevant molecules in different sample matrices including urban wastewater treatment effluent, human urine, and river water. We find in each case that excellent separations of the target compounds from the sample matrix are obtained using one set of very similar separation conditions for all of the target compound/sample matrix combinations, thereby significantly reducing the normally tedious method development process. A rigorous quantitative comparison of this approach to conventional 1DLC-MS/MS also shows that targeted 3DLC with UV detection is quantitatively accurate for the target compounds studied, with method detection limits in the low parts-per-trillion range of concentrations. We believe this work represents a first step toward the development of a targeted 3D analysis system that will be more effective than previous 2D separations as a tool for the rapid development of robust methods for quantitation of low concentration constituents in complex mixtures. PMID:21047638

Simpkins, Scott W; Bedard, Jeremy W; Groskreutz, Stephen R; Swenson, Michael M; Liskutin, Tomas E; Stoll, Dwight R

2010-12-01

351

Chirospecific analysis of plant volatiles  

NASA Astrophysics Data System (ADS)

Characteristic features of the analysis of plant volatiles by enantioselective gas (gas-liquid) chromatography and gas chromatography/mass spectrometry are discussed. The most recent advances in the design of enantioselective stationary phases are surveyed. Examples of the preparation of the most efficient phases based on modified cyclodextrins are given. Current knowledge on the successful analytical resolution of different types of plant volatiles (aliphatic and aromatic compounds and mono-, sesqui- and diterpene derivatives) into optical antipodes is systematically described. Chiral stationary phases used for these purposes, temperature conditions and enantiomer separation factors are summarised. Examples of the enantiomeric resolution of fragrance compounds and components of plant extracts, wines and essential oils are given.

Tkachev, A. V.

2007-10-01

352

Processing of Aroma Chemicals and Fragrance Materials, Socialist Republic of Viet Nam. Technical Report: Application of Gas Liquid Chromatography.  

National Technical Information Service (NTIS)

Vietnam has been a producer of natural essential oils. The government through the agency of UNDP and UNIDO has provided the industry with R & D backup in the form of a project titled: Processing of Vietnamese essential oils and related natural products. T...

M. L. Maheshwari

1992-01-01

353

Simultaneous determination of acetylsalicylic acid and salicylic acid by gas-liquid chromatography using a new methylation technique  

Microsoft Academic Search

A GLC method of simultaneous determination of acetylsalicylic acid and salicylic acid after a simple and elegant methylation is presented. Acetonic solution of these acids is refluxed with methyl iodide and potassium carbonate for 30 minutes and then gas chromatographed with a column of 3% OV 17 on Varaport 30, 70–80 mesh, AW\\/DMCS. The methylation is quantitative in 0.001–0.1 M

S. Laik Ali

1973-01-01

354

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

355

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

356

Counter-current chromatography for oil analysis: retention features and kinetic effects.  

PubMed

Application of counter-current chromatography (CCC) for oil analysis has been suggested for the first time. CCC looks very promising as a tool for pre-concentration and isolation of trace elements from oil. Features of stationary phase retention of two-phase liquid systems (oil or oil products-aqueous nitric acid solutions) in CCC have been investigated. The influence of physicochemical properties of crude oil and oil products used as a mobile phase on the volume of stationary phase (acidic aqueous solutions) retained in CCC was studied. Chromatographic behavior of several oil samples was studied. It has been shown that physicochemical properties of test oil influence its chromatographic behavior. Optimal values of density and viscosity (rho<0.85g/cm(3), n<7cSt) of crude oil and oil products that could be analyzed using CCC were estimated. The influence of the column rotational speed and flow rate of mobile phase on the stationary phase retention was also investigated. It is known that kinetic aspects (mass transfer of elements between phases) can play a very important role in selecting an optimal composition of stationary phase for the pre-concentration of elements from oil. The influence of nitric acid concentration in the stationary phase on mass transfer was studied. Kinetic characteristic for trace element recovery has been investigated for the optimization of pre-concentration conditions of trace elements from crude oil and oil products. The extraction recoveries of Zn, Mn, Fe, Ni, V, Cu, Cd, Pb and Ba by CCC in dynamic mode are in the range of 75-95% while they are lower than 35% under batch conditions. PMID:19232415

Maryutina, Tatyana A; Soin, Alexander V; Katasonova, Olesya N

2009-05-01

357

[Analysis of supercritical fluid extracts of Radix caulophylli with gas chromatography-mass spectrometry].  

PubMed

To analyze the constituents in supercritical fluid CO2 extraction (SFE-CO2) of Radix caulophylli, the Radix caulophylli was extracted with SFE-CO2, and analyzed by gas chromatography-mass spectrometry (GC-MS). The GC-MS analysis with a DB-5MS capillary column (30 mm x 0.32 mm ID, 0.25 microm film thickness) was used. The inlet temperature was maintained at 280 degrees C. The column oven was held at 80 degrees C for 2 min, then programmed from 80 to 280 degrees C at 5 degrees C x min(-1) and, finally, held for 4 min. Helium at a constant flow rate of 2.0 mL x min(-1) was used as the carrier gas. The mass spectrometry conditions were as follows: ionization energy, 70 eV; ion source temperature, 200 degrees C. The mass selective detector was operated in the TIC mode (m/z was from 40 - 500). For the first time 49 peaks were separated and identified, the compounds were quantitatively determined by normalization method, and the identified compounds represent 97.44% of total GC peak areas. Viz, n-hexadecanoic acid (31.4%), (E, E) -9, 12-octadecadienoic acid (26.54%), (Z)-7-tetradecenal (9.4%), hexadecenoic acid (3.23%), 10-undecenal (3.22%), octadecanoic acid (2.25%), and caulophylline (1.76%) etc. The results will provide important foundation for understanding the constituents and further exploitation of Radix caulophylli. PMID:17703777

Wang, Si-Cen; Chen, Qin-Hua; Wei, Yao-Yuan; Li, Han-Wen; He, Lang-Chong

2007-05-01

358

Development of an enantioselective two-dimensional liquid chromatography-atmospheric pressure photoionization-tandem mass spectrometry method for the analysis of methylsulfonyl polychlorinated biphenyls in tissue extracts.  

E-print Network

??An enantioselective heart-cut two-dimensional liquid chromatography-atmospheric pressure photoionization-tandem mass spectrometry method was developed for the analysis of 25 methylsulfonyl polychlorinated biphenyl metabolites in tissue extracts.… (more)

Cooper, Victoria Irene

2011-01-01

359

Validation of pentaacetylaldononitrile derivative for dual 2H gas chromatography/mass spectrometry and 13C gas chromatography/combustion/isotope ratio mass spectrometry analysis of glucose.  

PubMed

A reference method to accurately define kinetics in response to the ingestion of glucose in terms of total, exogenous and endogenous glucose is to use stable-isotope-labelled compounds such as 2H and 13C glucose followed by gas chromatography/mass spectrometry (GC/MS) and gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) analysis. The use of the usual pentaacetyl (5Ac) derivative generates difficulties in obtaining accurate and reproducible results due to the two chromatographic peaks for the syn and anti isomers, and to the isotopic effect occurring during acetylation. Therefore, the pentaacetylaldononitrile derivative (Aldo) was validated for both isotopes, and compared with the 5Ac derivative. A correction factor including carbon atom dilution (stoichiometric equation) and the kinetic isotopic effect (KIE) was determined. Analytical validation results for the 2H GC/MS and 13C GC/C/IRMS measurements produced acceptable results with both derivatives. When 2H enrichments of plasma samples were < or = 1 mol % excess (MPE), the repeatability (RSD(Aldo Intra assay and Intra day) <0.94%, RSD(5Ac Intra assay and Intra day) <3.29%), accuracy (Aldo <3.4%, 5Ac <29.0%), and stability of the derivatized samples were significantly better when the Aldo derivatives of the plasma samples were used (p < 0.05). When the glucose kinetics were assessed in nine human subjects, after glucose ingestion, the plasma glucose 2H enrichments were identical with both derivatives, whereas the 13C enrichments needed a correction factor to fit together. Due to KIE variation, this correction factor was not constant and had to be calculated for each batch of analyses, to obtain satisfactory results. Mean quantities of exogenous glucose exhibit marked difference (20.9 +/- 1.3g (5Ac) vs. 26.7 +/- 2.5g (Aldo)) when calculated with stoichiometric correction, but fit perfectly when calculated after application of the correction factor (22.1 +/- 1.3g (5Ac) vs. 22.9 +/- 1.9g (Aldo)). Finally, the pentaacetylaldononitrile derivative, used here in GC/C/IRMS for the first time, enables measurement of 2H and 13C enrichments in plasma glucose with a single sample preparation. PMID:19904737

Sauvinet, Valérie; Gabert, Laure; Qin, Du; Louche-Pélissier, Corinne; Laville, Martine; Désage, Michel

2009-12-01

360

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

2011-05-23

361

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

362

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

363

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

364

A Novel Charged Medium Consisting of Gas-Liquid Interfacial Plasmas  

NASA Astrophysics Data System (ADS)

Due to the unique properties of ionic liquids such as their extremely low vapor pressure and high heat capacity, we succeed in creating the reactive gas (plasmas)—liquid (ionic liquids) interfacial field under a low gas pressure condition, where the plasma ion behavior can be controlled. The effects of the plasma ion irradiation on the liquid medium are quantitatively revealed for the first time. In connection with the plasma ion irradiation, the potential structure and optical emission properties of the gas-liquid interfacial plasma are investigated by changing a polarity of the electrode in the liquid to evaluate the plasma-liquid interactions. These results would contribute to synthesizing the metal nanoparticles with carbon nanotubes as a template in the ionic liquid. It is found that the high density, mono-dispersed, and isolated metal nanoparticles are synthesized between or inside the carbon nanotubes by controlling the gas-liquid interfacial plasmas. Furthermore, we can form novel nano-bio composite materials, such as DNA encapsulated carbon nanotubes using the plasma ion irradiation method in an electrolyte plasma with DNA, and demonstrate modifications of the electrical properties of the carbon nanotubes depending on the kinds of encapsulated DNA for the first time.

Kaneko, Toshiro; Hatakeyama, Rikizo

2009-11-01

365

A Novel Charged Medium Consisting of Gas-Liquid Interfacial Plasmas  

SciTech Connect

Due to the unique properties of ionic liquids such as their extremely low vapor pressure and high heat capacity, we succeed in creating the reactive gas (plasmas)--liquid (ionic liquids) interfacial field under a low gas pressure condition, where the plasma ion behavior can be controlled. The effects of the plasma ion irradiation on the liquid medium are quantitatively revealed for the first time. In connection with the plasma ion irradiation, the potential structure and optical emission properties of the gas-liquid interfacial plasma are investigated by changing a polarity of the electrode in the liquid to evaluate the plasma-liquid interactions. These results would contribute to synthesizing the metal nanoparticles with carbon nanotubes as a template in the ionic liquid. It is found that the high density, mono-dispersed, and isolated metal nanoparticles are synthesized between or inside the carbon nanotubes by controlling the gas-liquid interfacial plasmas. Furthermore, we can form novel nano-bio composite materials, such as DNA encapsulated carbon nanotubes using the plasma ion irradiation method in an electrolyte plasma with DNA, and demonstrate modifications of the electrical properties of the carbon nanotubes depending on the kinds of encapsulated DNA for the first time.

Kaneko, Toshiro; Hatakeyama, Rikizo [Department of Electronic Engineering, Tohoku University, Sendai 980-8579 (Japan)

2009-11-10

366

Optimization of enrichment conditions on TiO2 chromatography using glycerol as an additive reagent for effective phosphoproteomic analysis.  

PubMed

Metal oxide affinity chromatography (MOAC) represented by titanium dioxide (TiO2) chromatography has been used for phosphopeptide enrichment from cell lysate digests prior to mass spectrometry. For in-depth phosphoproteomic analysis, it is important for MOAC to achieve high phosphopeptide enrichment efficiency by optimizing purification conditions. However, there are some differences in phosphopeptide selectivity and specificity enriched by various TiO2 materials and procedures. Here, we report that binding/wash buffers containing polyhydric alcohols, such as glycerol, markedly improve phosphopeptide selectivity from complex peptide mixtures. In addition, the elution conditions combined with secondary amines, such as bis-Tris propane, made it possible to recover phosphopeptides with highly hydrophobic properties and/or longer peptide lengths. To assess the practical applicability of our improved method, we confirmed using PC3 prostate cancer cells. By combining the hydrophilic interaction chromatography (HILIC) with the optimized TiO2 enrichment method prior to LC-MS/MS analysis, over 8300 phosphorylation sites and 2600 phosphoproteins were identified. Additionally, some dephosphorylations of those were identified by treatment with dasatinib for a kinase inhibitor. These results indicate that our method is applicable to understanding the profiling of kinase inhibitors such as anticancer compounds, which will be useful for drug discovery and development. PMID:24245541

Fukuda, Isao; Hirabayashi-Ishioka, Yoshino; Sakikawa, Ikue; Ota, Takeshi; Yokoyama, Mari; Uchiumi, Takaoki; Morita, Atsushi

2013-12-01

367

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

368

Analysis of the temporal performance of one versus on-line comprehensive two-dimensional liquid chromatography.  

PubMed

Our purpose is to generalize the chief conclusion of earlier studies based on complex maize seed extract samples that indicated that at very short times (less than 5 min) the peak capacity of 1D liquid chromatography was better than that of comprehensive, on-line 2D liquid chromatography (LC × LC), but that the LC × LC method begins to out-perform the 1D method at surprisingly short analysis times of only 5-10 min. We call the analysis time at which the peak capacities of 1D and LC × LC become equal the "crossover time." We quantify the importance of various system parameters such as the 1D peak capacity, the second dimension cycle time and second dimension peak capacity, and fractional coverage of the two-dimensional separation space on the crossover time of 1D versus LC × LC chromatography. For ranges of these parameters used in our earlier experimental studies, we believe that crossover times will generally be between 3 and 8 min under optimized on-line LC × LC conditions. PMID:23992843

Potts, Lawrence W; Carr, Peter W

2013-10-01

369

Analysis of succinylcholine in tissues and body fluids by ion-pair extraction and gas chromatography-mass spectrometry.  

PubMed

The neuromuscular blocking agent succinylcholine (SCh) has been identified and quantitated in biological material using gas chromatography-mass spectrometry. The bisquaternary ammonium compound SCh is extracted from tissue homogenates or body fluids into dichloromethane as an ion pair with hexanitrodiphenylamine (DPA). The evaporated ion pair residue is demethylated with sodium benzenethiolate to form the corresponding tertiary amine which is identified and quantitated by gas chromatography-mass spectrometry using a glass capillary column coated with SE 52. In the quantitative analysis deuterated SCh is used as internal standard. The instrument is focussed on m/z 58 for demethylated SCh and m/z 62 or 64 for the internal standard. Concentrations as low as 5 ng SCh iodide/g tissue or body fluid are easily detected. PMID:6578742

Nordgren, I K; Forney, R B; Carroll, F T; Holmstedt, B R; Jäderholm-Ek, I; Pettersson, B M

1983-01-01

370

Feasibility of thiocarbamate pesticide analysis in apples by supercritical fluid extraction and high-performance liquid chromatography.  

PubMed

Supercritical fluid extraction produced comparable results with liquid-solid extraction for the analysis of several thiocarbamate pesticides from apples at the 2 ppm spike level. These results were achieved with a simple one-step extraction procedure. The use of diatomaceous earth (Celite, Supelco, Inc.; Bellefonte, PA) served to increase thiocarbamate recoveries by aiding in the immobilization of the aqueous component of the apple matrix. High-performance liquid chromatography coupled with ultraviolet absorbance detection (HPLC-UV) had the most viable means of quantitation when compared with micro-HPLC-sulfur chemiluminescence detection (SCD) and gas chromatography-flame-ionization detection (GC-FID). The small injection volumes used with the micro-HPLC-SCD system made thiocarbamate detection at a spiking level of 2 ppm impossible. SCD did provide, however, valuable qualitative information about the nature of the apple coextractants. PMID:8376544

Howard, A L; Braue, C; Taylor, L T

1993-08-01

371

Simultaneous analysis of fourteen tertiary amine stimulants in human urine for doping control purposes by liquid chromatography–tandem mass spectrometry and gas chromatography–mass spectrometry  

Microsoft Academic Search

A method for the simultaneous screening and confirmation of the presence of fourteen tertiary amine stimulants in human urine by gas chromatography–mass spectrometry (GC–MS) in combination with liquid chromatography–tandem mass spectrometry (LC–MS\\/MS) has been developed and validated. Solid phase extraction (SPE) and liquid–liquid extraction (LLE) approaches were utilized for the pre-treatment of the urine samples. The study indicated that the

Jianghai Lu; San Wang; Ying Dong; Xiaobing Wang; Shuming Yang; Jianli Zhang; Jing Deng; Yang Qin; Youxuan Xu; Moutian Wu; Gangfeng Ouyang

2010-01-01

372

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

373

Analysis of allergens in tubeimu saponin extracts by using rat basophilic leukemia 2H3 cell-based affinity chromatography coupled to liquid chromatography and mass spectrometry.  

PubMed

An affinity two-dimensional chromatography method was developed for the recognition, separation, and identification of allergic components from tubeimu saponin extracts, a preparation often injected to treat various conditions as indicated by traditional Chinese medicine. Rat basophilic leukemia-2H3 cell membranes were used as the stationary phase of a membrane affinity chromatography column to capture components with affinity for mast cells that could be involved in a degranulation reaction. The retained components were enriched and analyzed by membrane affinity chromatography with liquid chromatography and mass spectrometry via a port switch valve. Suitability and reliability of the method was investigated using appropriate standards, and then, the method was applied to identify components retained from tubeimu saponin extracts. Tubeimoside A was identified in this way as a potential allergen, and degranulation assays confirmed that tubeimoside A induces RBL-2H3 cell degranulation in a dose-dependent manner. An increase in Ca(2+) influx indicated that degranulation induced by tubeimoside A is likely Ca(2+) dependent. Coupled with the degranulation assay, RBL-2H3 cell-based affinity chromatography coupled with liquid chromatography and mass spectrometry is an effective method for screening and identifying allergic components from tubeimu saponin extracts. PMID:25243709

Zhang, Tao; Han, Shengli; Liu, Qi; Guo, Ying; He, Langchong

2014-11-01

374

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.

375

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

Microsoft Academic Search

A method for the isolation and derivatization of plasma taurine is described that allows stable isotope determinations of taurine to be made by gas chromatography-mass spectrometry. The isolation procedure can be applied to 0.1 ml of plasma; the recovery of plasma taurine was 70 to 80%. For gc separation, taurine was converted to its dimethylaminomethylene methyl ester derivative which could

C. S. Irving; P. D. Klein

1980-01-01

376

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

377

Qualitative Analysis by Gas Chromatography: GC versus the Nose in Formulating Artificial Fruit Flavors.  

ERIC Educational Resources Information Center

Describes an undergraduate laboratory experiment used to illustrate the use of gas chromatography retention indices for the identification of unknown compounds, specifically for the identification of unknown compounds and for the identification of the volatile compounds responsible for the odor of the banana. Procedures, reference data, and sample…

Rasmussen, P. W.

1984-01-01

378

(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...

379

ANALYSIS OF SELECTED PYRETHROID PESTICIDES USING REVERSE PHASE HIGH PRESSURE LIQUID CHROMATOGRAPHY/UV  

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 py...

380

Confirmatory analysis of firocoxib in bovine milk by rapid resolution liquid chromatography tandem mass spectrometry  

Microsoft Academic Search

A rapid method has been developed to analyse for firocoxib (FIRO) residue in bovine milk. Milk samples were extracted with acetonitrile and sample extracts were purified on Evolute™ ABN solid phase extraction cartridges. Aliquots were analysed by rapid resolution liquid chromatography tandem mass spectrometry (RRLC–MS\\/MS). The method was validated in bovine milk, according to the criteria defined in Commission Decision

Geraldine Dowling; Pasquale Gallo; Liam Regan

2009-01-01

381

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...

382

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

383

Study of Co-Current and Counter-Current Gas-Liquid Two-Phase Flow Through Packed Bed in Microgravity  

NASA Astrophysics Data System (ADS)

The main goal of the project is to obtain new experimental data and development of models on the co-current and counter-current gas-liquid two-phase flow through a packed bed in microgravity and characterize the flow regime transition, pressure drop, void and interfacial area distribution, and liquid hold up. Experimental data will be obtained for earth gravity and microgravity conditions. Models will be developed for the prediction of flow regime transition, void fraction distribution and interfacial area concentration, which are key parameters to characterize the packed bed performance. Thus the specific objectives of the proposed research are to: (1) Develop experiments for the study of the gas liquid two-phase flow through the packed bed with three different flow combinations: co-current down flow, co-current upflow and counter current flow. (2) Develop pore scale and bed scale two-phase instrumentation for measurement of flow regime transition, void distribution and gas-liquid interfacial area concentration in the packed bed. (3) Obtain database on flow regime transition, pressure drop, void distribution, interfacial area concentration and liquid hold up as a function of bed characteristics such as bed particle size, porosity, and liquid properties such as viscosity and surface tension. (4) Develop mathematical model for flow regime transition, void fraction distribution and interfacial area concentration for co-current gas-liquid flow through the porous bed in gravity and micro gravity conditions.(4) Develop mathematical model for the flooding phenomena in counter-current gas-liquid flow through the porous bed in gravity and micro gravity conditions. The present proposal addresses the most important topic of HEDS-specific microgravity fluid physics research identified by NASA 's one of the strategic enterprises, OBPR Enterprise. The proposed project is well defined and makes efficient use of the ground-based parabolic flight research aircraft facility. The project spans for four years. The first two years are devoted to ground based flight definition experimental and modeling program. During the next two years microgravity flight tests are carried out using the ground-based parabolic flight research aircraft. The experimental program consists of a design of a packed bed loop using a scaling analysis, performing experiments for various parameters: bed diameter, packing size, liquid surface tension, and liquid viscosity. Figure 1 shows the schematic of the test loop. A packed bed sections of 15 cm diameter and 10 cm diameter are designed with sphere packing particles of diameter, 6 mm and 3 mm. The fluid combination used are : 1)water, air, (2) alcohol-water mixture (50%, 80% methanol) and air, and (3) glycerol-water mixture and air (50%, and 64% glycerol weight percent). The loop is instrumented to provide detailed measurement at pore and bed level parameters.

Revankar, Shripad T.

2002-11-01

384

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.

2011-05-26

385

Multiclass mycotoxin analysis in food, environmental and biological matrices with chromatography/mass spectrometry.  

PubMed

Mold metabolites that can elicit deleterious effects on other organisms are classified as mycotoxins. Human exposure to mycotoxins occurs mostly through the intake of contaminated agricultural products or residues due to carry over or metabolite products in foods of animal origin such as milk and eggs, but can also occur by dermal contact and inhalation. Mycotoxins contained in moldy foods, but also in damp interiors, can cause diseases in humans and animals. Nephropathy, various types of cancer, alimentary toxic aleukia, hepatic diseases, various hemorrhagic syndromes, and immune and neurological disorders are the most common diseases that can be related to mycotoxicosis. The absence or presence of mold infestation and its propagation are seldom correlated with mycotoxin presence. Mycotoxins must be determined directly, and suitable analytical methods are necessary. Hundreds of mycotoxins have been recognized, but only for a few of them, and in a restricted number of utilities, a maximum acceptable level has been regulated by law. However, mycotoxins seldom develop alone; more often various types and/or classes form in the same substrate. The co-occurrence might render the individual mycotoxin tolerance dose irrelevant, and therefore the mere presence of multiple mycotoxins should be considered a risk factor. The advantage of chromatography/mass spectrometry (MS) is that many compounds can be determined and confirmed in one analysis. This review illustrates the state-of-the-art of mycotoxin MS-based analytical methods for multiclass, multianalyte determination in all the matrices in which they appear. A chapter is devoted to the history of the long-standing coexistence and interaction among humans, domestic animals and mycotoxicosis, and the history of the discovery of mycotoxins. Quality assurance, although this topic relates to analytical chemistry in general, has been also examined for mycotoxin analysis as a preliminary to the systematic literature excursus. Sample handling is a crucial step to devise a multiclass analytical method; so when possible, it has been treated separately for a better comparison before tackling the instrumental part of the whole analytical method. This structure has resulted sometimes in unavoidable redundancies, because it was also important to underline the interconnection. Most reviews do not deal with all the possible mycotoxin sources, including the environmental ones. The focus of this review is the analytical methods based on MS for multimycotoxin class determination. Because the final purpose to devise multimycotoxin analysis should be the assessment of the danger to health of exposition to multitoxicants of natural origin (and possibly also the interaction with anthropogenic contaminants), therefore also the analytical methods for environmental relevant mycotoxins have been thoroughly reviewed. Finally, because the best way to shed light on actual risk assessment could be the individuation of exposure biomarkers, the review covers also the scarce literature on biological fluids. PMID:22065561

Capriotti, Anna Laura; Caruso, Giuseppe; Cavaliere, Chiara; Foglia, Patrizia; Samperi, Roberto; Laganà, Aldo

2012-01-01

386

Development of capillary size exclusion chromatography for the analysis of monoclonal antibody fragments extracted from human vitreous humor.  

PubMed

Recombinant antigen-binding fragments (Fabs) are currently on the market and in development for the treatment of ophthalmologic indications. Recently, Quality by Design (QbD) initiatives have been implemented that emphasize understanding the relationship between quality attributes of the product and their impact on safety and efficacy. In particular, changes in product quality once the protein is administered to the patient are of particular interest. Knowledge of protein aggregation in vivo is of importance due to the possibility of antibody aggregates eliciting an immunogenic response in the patient. Presently, there are few analytical methods with adequate sensitivity to analyze Fab aggregates in human vitreous humor (HVH) because the Fab amount available for analysis is often quite low. Here, we report the development of a highly sensitive capillary size exclusion chromatography (SEC) methodology for Fab aggregate analysis in HVH. We demonstrate a process to perform capillary SEC to analyze Fabs with picogram sensitivity and an RSD of less than 8% for the relative peak area of high molecular weight species (HMWS). In addition, we have developed a Protein G affinity chromatography method to capture Fabs from HVH for capillary SEC analysis. Recovery efficiencies ranging from 86 to 99% were achieved using this recovery method with 300 ?L HVH samples containing Fab1. Finally, we demonstrate the applicability of the methodology by quantifying Fab aggregates in HVH, which can potentially be used for aggregate analysis of clinically relevant samples. PMID:23177154

Rea, Jennifer C; Lou, Yun; Cuzzi, Joel; Hu, Yuhua; de Jong, Isabella; Wang, Yajun Jennifer; Farnan, Dell

2012-12-28

387

Combined Eulerian-VOF-Lagrangian method for general gas-liquid flow applications  

SciTech Connect

This article summarizes the technical development and validation of a multiphase computational fluid dynamics (CFD) numerical method using a combined volume-of-fluid (VOF)/Lagrangian tracking model to analyze general dispersed multiphase-flow problems with free surfaces. The gas-liquid interfacial mass, momentum, and energy transfer are modeled by continuum surface mechanisms. A high-order TVD scheme is also implemented for capturing sharp interfaces between immiscible phases. The objectives of the present study are to develop and verify the fractional volume-of-fluid cell partitioning approach into a predictor-corrector algorithm, which is suitable for solving fluid flows at all speeds regimes, and to demonstrate the effectiveness of the present approach by simulating benchmark problems including coaxial jet atomization.

Chen, Y.S.; Shang, H.M.; Liaw, P. [Engineering Sciences, Inc., Huntsville, AL (United States); Chen, C.P. [Univ. of Alabama, Huntsville, AL (United States); Wang, T.S. [NASA Marshall Space Flight Center, Huntsville, AL (United States)

1996-12-01

388

Backlight imaging tomography for gas liquid two-phase flow in a helically coiled tube  

NASA Astrophysics Data System (ADS)

Air-water two-phase flow in a helically coiled tube is investigated using backlight imaging tomography to elucidate the effect of centrifugal acceleration on phase distribution and interfacial structure. Superficial velocities up to 6 m s-1 in 20 mm diameter tube are tested. We focused on a slug flow regime in which centrifugal acceleration dominates the flow. The interfacial structure is visualized in six directions using a set of originally designed mirror-mounted water jackets. A temporal expansion image is made from line-sampled images and is used to reconstruct phase distribution through a linear backward projection algorithm. The present topography measurement showed various new features of gas-liquid two-phase flow in a helically coiled tube, such as a wall-covering effect in the case of high superficial velocity.

Murai, Yuichi; Oiwa, Hiroshi; Sasaki, Toshio; Kondou, Katsuhiko; Yoshikawa, Shinji; Yamamoto, Fujio

2005-07-01

389

On the induction criterion of the Marangoni convection at the gas/liquid interface  

SciTech Connect

Some spreading solutes were found to be effective in enhancing the absorption rate by provoking interfacial turbulence at the gas-liquid surface. In this work, the induction criterion of the Marangoni convection is explored experimentally and theoretically by using aqueous solutions of normal alcohols and surfactants as spreading liquids. The experimental results show that aqueous solutions of methanol, ethanol, n-propanol, n-butanol, and n-pentanol may induce significant interfacial turbulence, and, on the other hand, aqueous solutions of n-hexanol, n-octanol, SDS, DTMAC, and Triton X-100 do not provoke noticeable interfacial turbulence. A dimensionless Marangoni number, Ma, based on film thickness {delta} is satisfactorily developed to evaluate the potentiality of a spreading liquid to produce interfacial turbulence. The critical Marangoni number, Ma, c, for the occurrence of the Marangoni convection is also determined.

Lu, H.H.; Yang, Y.M.; Maa, J.R. [National Cheng Kung Univ., Tainan (Taiwan, Province of China). Dept. of Chemical Engineering] [National Cheng Kung Univ., Tainan (Taiwan, Province of China). Dept. of Chemical Engineering

1997-02-01

390

Performance improvement of gas liquid cylindrical cyclone separators using passive control system  

SciTech Connect

The performance of Gas Liquid Cylindrical Cyclone (GLCC) separators can be improved by reducing or eliminating liquid carry-over into the gas stream or gas carry-under through liquid stream, utilizing suitable liquid level control. In this study, a new passive control system has been developed for the GLCC, in which the control is achieved by utilizing only the liquid flow energy. Passive control system is highly desirable for remote, unmanned location operated with no external power source. Salient features of this design are presented here. Detailed experimental and modeling studies have been conducted to evaluate the improvement in the GLCC operational envelope for liquid carry-over with the passive control system. The results demonstrate that a passive control system is feasible for operation in normal slug flow conditions. The result of this study could also form the basis for future development of active control systems using classical control approach.

Wang, S.; Mohan, R.; Shoham, O. [Univ. of Tulsa, OK (United States); Kouba, G.

1998-12-31

391

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

392

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

393

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

394

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

395

Mixed refrigerants proven efficient in natural-gas-liquids recovery process  

SciTech Connect

Lower processing temperatures for higher recoveries of natural gas liquids (NGL) leads to increasingly complex and expensive refrigeration techniques. This paper describes the mixed component refrigeration technique and that it has been proven as a viable alternative to the turboexpander plant. Mixed component refrigeration systems have been primarily used in applications such as LNG terminals and peak-shaving plants, where overall compression horse-power requirements are of primary concern due to operating cost. Recently, development of high pressure, brazed aluminum plate/fin exchangers and increasing compression costs have made economic potential of the mixed refrigerant alternative apparent. If the residue gas must be compressed to the same pressure as the plant inlet using the turbo-expander design, the mixed refrigerant system will require approximately 15% less horsepower for the same liquids production.

Mac Kenzie, D.H.

1985-03-04

396

Thermal dispersion in vertical gas-liquid flows with foaming and non-foaming liquids  

SciTech Connect

Heat transfer experiments have been performed in gas-liquid upwards flow in a vertical column with non-foaming (water) and foaming (kerosene) liquids. The main purpose of the experiments has been to characterized the degree of thermal mixing in the system. For the range of conditions employed, the nonfoaming liquid exhibits complete mixing a low liquid superficial velocities. An increased in liquid velocity leads to incomplete mixing. In the latter case, the thermal dispersion coefficient at low gas superficial velocities is larger than what correlations in the literature predict. For the foaming liquid, when foaming and bubbling regions coexist in the bubble column, each region behaves as a completely-mixed subsystem.

Pino, L.R.Z.; Saez, A.E. [Univ. Simmon Bolivar, Caracas (Venezuela). Dept. de Termodinamica y Fenomenos de Transferecia] [Univ. Simmon Bolivar, Caracas (Venezuela). Dept. de Termodinamica y Fenomenos de Transferecia

1995-05-01

397

Affinity chromatography and capillary electrophoresis for analysis of the yeast ribosomal proteins.  

PubMed

We present a top down separation platform for yeast ribosomal proteins using affinity chromatography and capillary electrophoresis which is designed to allow deposition of proteins onto a substrate. FLAG tagged ribosomes were affinity purified, and rRNA acid precipitation was performed on the ribosomes followed by capillary electrophoresis to separate the ribosomal proteins. Over 26 peaks were detected with excellent reproducibility (<0.5% RSD migration time). This is the first reported separation of eukaryotic ribosomal proteins using capillary electrophoresis. The two stages in this workflow, affinity chromatography and capillary electrophoresis, share the advantages that they are fast, flexible and have small sample requirements in comparison to more commonly used techniques. This method is a remarkably quick route from cell to separation that has the potential to be coupled to high throughput readout platforms for studies of the ribosomal proteome. PMID:22531133

Goyder, Miriam S; Willison, Keith R; Klug, David R; Demello, Andrew J; Ces, Oscar

2012-04-01

398

High Performance Liquid Chromatography Method for Residues Analysis of Thidiazuron in Apple and Soil  

Microsoft Academic Search

A rapid, sensitive and reliable analytical method for thidiazuron residues in apple and soil was established. The residual\\u000a levels of the pesticide in apple and soil were determined by high performance liquid chromatography (HPLC) with UV detector.\\u000a Samples of apple and soil were extracted with acetonitrile–water solutions, and then cleaned up by Florisil or C18 cartridges. The results showed good

Ji-Ye HuYa-Qin; Ya-Qin Hu; Yang Chen; Tao Yang

399

Principal component analysis of polymer–solvent and filler–solvent interactions by inverse gas chromatography  

Microsoft Academic Search

Polymers (polyethylene, polyurethane), silica and modified silicas (modified with: N-2-aminoethyl-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-merkaptopropyltrimethoxysilane, triethoxyoctylsilane) were examined by inverse gas chromatography at four different temperatures: 363, 383, 393 and 403K. The modifiers of silica were applied at five different concentrations. Small amounts of the following test solutes were injected to achieve the infinite dilution conditions: pentane, hexane, heptane, octane, nonane, dichloromethane, chloroform,

Károly Héberger; Kasylda Milczewska; Adam Voelkel

2005-01-01

400

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

401

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

402

Stability-indicating micellar electrokinetic chromatography method for the analysis of sumatriptan succinate in pharmaceutical formulations  

Microsoft Academic Search

A micellar electrokinetic chromatography method for the determination of sumatriptan succinate in pharmaceutical formulations was developed. The effects of several factors such as pH, surfactant and buffer concentration, applied voltage, capillary temperature, and injection time were investigated. Separation took about 5min using phenobarbital as internal standard. The separation was carried out in reversed polarity mode at 20°C, 26kV and using

Khaldun M. Al Azzam; Bahruddin Saad; Chai Yuan Tat; Ishak Mat; Hassan Y. Aboul-Enein

2011-01-01

403

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

Microsoft Academic Search

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

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

2002-01-01

404

Application of gradient high-performance liquid chromatography to the analysis of some multicomponent pharmaceutical preparations  

Microsoft Academic Search

Procedures were developed for determining streptocide and norsulfazole in the Ingalipt aerosol; dexpanthenol and nipagin in\\u000a the Dekspantenol aerosol; and oxymetazoline and benzalkonium chloride in a nasal spray by reversed-phase high-performance\\u000a liquid chromatography (HPLC) in the gradient elution mode using the CH3CN-0.025 M aqueous solution mixture of KH2PO4 (pH 3.0) and UV detection. The developed procedures are comparable in accuracy

G. B. Golubitskii; E. M. Basova; V. M. Ivanov

2008-01-01

405

ULTRA PERFORMANCE LIQUID CHROMATOGRAPHY ANALYSIS OF FLUNITRAZEPAM AND 7-AMINOFLUNITRAZEPAM IN HUMAN PLASMA  

Microsoft Academic Search

A high-throughput ultra-performance liquid chromatography (UPLC) method with UV detection was elaborated and validated for the simultaneous quantification of flunitrazepam and its major metabolite, 7-aminoflunitrazepam, in human plasma. After a simple liquid-liquid extraction with ethyl acetate, chromatographic separation was performed on a BEH C18 chromatographic column with a binary mixture of acetonitrile\\/10 mM potassium monohydrogen phosphate (pH = 8.5) as the mobile phase,

Béla Kiss; Catalina Bogdan; Anca Pop; Felicia Loghin

2010-01-01

406

The Analysis of Purines from Rabbit Kidney Preservation Media by High Pressure Liquid Chromatography  

Microsoft Academic Search

This paper demonstrates the application of High Pressure Liquid Chromatography (H.P.L.C.) for the separation and measurement of purines from perfusates of rabbit kidneys preserved for transplantation. A ?-Bondapak C18 reverse phase column at pH 4.5 was included in a convex gradient elution program to facilitate optimal resolution in minimum time. The eluent comprised dipotassium hydrogen phosphate (K2HPO4) buffer with a

Kathryn M. Taylor; Lindsay Chase; Michael Bewick

1978-01-01

407

Application of comprehensive two-dimensional gas chromatography to drugs analysis in doping control  

Microsoft Academic Search

Comprehensive two-dimensional gas chromatography (GC×GC) now occupies a niche within the GC technology regime. The technique is undeniably unique in the manner in which the experiment is conducted, the way results are presented and the interpretive opportunities offered. For the 1000th volume of this journal it is appropriate to expand upon these features, and review the progress made in GC×GC

A. J. Kueh; P. J. Marriott; P. M. Wynne; J. H. Vine

2003-01-01

408

Doping control analysis of trenbolone and related compounds using liquid chromatography–tandem mass spectrometry  

Microsoft Academic Search

Trenbolone (17?-hydroxy-estra-4,9,11-trien-3-one) and its derivatives such as 17?-methyltrenbolone represent a class of highly potent anabolic–androgenic steroids, which are prohibited in sports according to the regulation of the World Anti-Doping Agency (WADA). Due to marginal gas chromatographic properties of these compounds but excellent proton affinities resulting from a large and conjugated ?-electron system, liquid chromatography–tandem mass spectrometry (LC–MS\\/MS) has been the

Mario Thevis; Sven Guddat; Wilhelm Schänzer

2009-01-01

409

Analysis of radioactive waste samples by ion chromatography-ICP\\/MS  

Microsoft Academic Search

A comprehensive ion chromatography (IC) with beta-counting (beta) and inductively coupled plasma mass spectrometry (ICP\\/MS) detection approach has been developed to separate and detect 20 radionuclides in a Hanford waste tank sample. The IC separation was performed using a multi-functional group (anion\\/cation) resin and eluents of oxalic acid, diglycolic acid, and hydrochloric acid. Shorter-lived radionuclides were detected by a solid-state

O. T. Farmer; J. H. Reeves; E. J. Wyse; C. J. Clemeston; C. J. Barinaga; M. R. Smith; D. W. Koppenaal

1994-01-01

410

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

411

Analysis of acrylamide in coffee and cocoa by isotope dilution liquid chromatography–tandem mass spectrometry  

Microsoft Academic Search

An accurate and precise method for the quantification of acrylamide using stable isotope dilution liquid chromatography–tandem\\u000a mass spectrometry was developed and used to measure acrylamide in coffee and cocoa samples. The sample preparation involved\\u000a extraction of the analyte and its internal standard, 13C3-acrylamide, into water and subsequent defatting of the aqueous extract with dichloromethane. An aliquot of the resulting\\u000a aqueous

Patricia C. Aguas; Matthew J. Fitzhenry; Georgina Giannikopoulos; Peter Varelis

2006-01-01

412

Liquid chromatography–tandem mass spectrometry analysis of nitazoxanide and its major metabolites in goat  

Microsoft Academic Search

A rapid, sensitive and specific liquid chromatography–electrospray ionization (ESI) tandem mass spectrometry (LC–MS–MS) method has been developed for the identification of nitazoxanide metabolites in goat plasma and urine. The purified samples was separated using an XTerra MS C8 column with the mobile phase consisted of acetonitrile and 10-mM ammonium acetate buffer (pH 2.5) followed a linear gradient elution, and detected

Zhanzhong Zhao; Lifang Zhang; Feiqun Xue; Xiaoyang Wang; Wenli Zheng; Tao Zhang; Chenzhong Fei; Keyu Zhang; Minqi Qiu; Ruixiang Xin; Fengkun Yang

2008-01-01

413

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

414

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

415

Simultaneous analysis and quantification of markers of manjisthadi churna using high performance thin layer chromatography.  

PubMed

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

416

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

417

Comparison of three buffer solutions for amino acid derivatization and following analysis by liquid chromatography electrospray mass spectrometry.  

PubMed

For reversed phase separation amino acids are usually derivatized. Several derivatization reactions are carried out at basic pH. In the present work, influence of three basic buffer solutions on liquid chromatography electrospray ionization mass-spectrometric (LC-ESI-MS) analysis of amino acid derivatives was studied. Borate buffer--the most common derivatization buffer--was found to influence ESI ionization up to 23 min retention time. For 9-fluorenylmethylmethoxycarbonyl chloride (Fmoc-Cl derivatization) carbonate buffer should be preferred as it provides higher responses. Hexafluoroisopropanol (HFIP) buffer improves chromatographic peak shapes and responses for diethyl ethoxymethylenemalonate (DEEMM) derivatives. PMID:22673814

Rebane, Riin; Herodes, Koit

2012-07-01

418

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

419

Chromatography, Absorption, and Fluorescence: A New Instrumental Analysis Experiment on the Measurement of Polycyclic Aromatic Hydrocarbons in Cigarette Smoke  

NASA Astrophysics Data System (ADS)

The recent approval by the American Chemical Society of an undergraduate chemistry degree with an option in environmental chemistry requires the development of new experiments that teach fundamental chemistry in the context of environmental issues. We present an experiment suitable for an undergraduate junior/senior-level instrumental analysis laboratory which illustrates the principles of high-performance liquid chromatography (HPLC) and its application to the identification and measurement of polycyclic aromatic hydrocarbons (PAH) in tobacco smoke. Absorption and fluorescence detection methods for PAH, especially the differences in sensitivity and selectivity of these methods, are clearly demonstrated along with the basic principles of HPLC.

Wingen, Lisa M.; Low, Jason C.; Finlayson-Pitts, Barbara J.

1998-12-01

420

Use of Two-Dimensional Liquid Chromatography Combined with Diode-Array and Mass Spectrometric Detection for Analysis of Compounds in Flos Lonicera  

Microsoft Academic Search

Comprehensive two-dimensional liquid chromatographic separation by means of a combination of ion-exchange chromatography (IEC)\\u000a and reversed-phase liquid chromatography (RPLC) has been realized and applied to the analysis of components of a traditional\\u000a Chinese medicine Flos Lonicera. In the first dimension the components of a Flos Lonicera extract is separated on strong anion-exchange (SAX) column according to the charge-exchange properties of

Xueguo Chen; Zhaolin Jiang; Yu Zhu; Jiayi Tan

2007-01-01

421

Carbon isotope ratio analysis of steroids by high-temperature liquid chromatography-isotope ratio mass spectrometry.  

PubMed

Generally, compound-specific isotope analysis of steroids is carried out by gas chromatography combined with isotope ratio mass spectrometry. Thus, a derivatization of the steroids prior to the measurement is compulsory, and a correction of the isotopic data is often necessary. To overcome this limitation, we present a new approach of high-temperature liquid chromatography coupled with photodiode array detection and isotope ratio mass spectrometry (HT-LC/PDA/IRMS) for the carbon isotope ratio analysis of unconjugated steroids. A steroid mixture containing 19-norandrosterone, testosterone, epitestosterone, androsterone, and 5?-pregnane-3?,17?,20?-triol was fully separated on a C4 column under high-temperature elution with water as the sole eluent. The accuracy for isotope analysis (±0.5 ‰) was around 20 ?g g(-1) for testosterone, epitestosterone (79 ng steroid absolute on column), and 30 ?g g(-1) for 19-norandrosterone, androsterone, and 5?-pregnane-3?,17?,20?-triol (119 ng steroid absolute on column). The applicability of the method was tested by measuring a pharmaceutical gel containing testosterone. With this work, the scope of LC/IRMS applications has been extended to nonpolar compounds. PMID:24491121

Zhang, Lijun; Thevis, Mario; Piper, Thomas; Jochmann, Maik A; Wolbert, J Benjamin; Kujawinski, Dorothea M; Wiese, Steffen; Teutenberg, Thorsten; Schmidt, Torsten C

2014-03-01

422

Analysis of cocaethylene, benzoylecgonine and cocaine in human urine by high-performance thin-layer chromatography with ultraviolet detection: a comparison with high-performance liquid chromatography  

Microsoft Academic Search

Cocaine and ethanol are frequently used at the same time, resulting in the formation of cocaethylene by transesterification. We studied the capability of high-performance thin-layer chromatography (HPTLC) to simultaneously detect cocaethylene, cocaine and benzoylecgonine in 16 urine specimens of drug addicts, previously tested as positive for benzoylecgonine at immunoenzymatic screening. Accuracy and precision, as well as detection and quantitation limits

Letizia Antonilli; Carmen Suriano; Maria Caterina Grassi; Paolo Nencini

2001-01-01

423

Fast analysis of doping agents in urine by ultra-high-pressure liquid chromatography–quadrupole time-of-flight mass spectrometry. II: Confirmatory analysis  

Microsoft Academic Search

For doping control, analyses of samples are generally achieved in two steps: a rapid screening and, in the case of a positive result, a confirmatory analysis. A two-step methodology based on ultra-high-pressure liquid chromatography coupled to a quadrupole time-of-flight mass spectrometry (UHPLC–QTOF-MS) was developed to screen and confirm 103 doping agents from various classes (e.g., ?-blockers, stimulants, diuretics, and narcotics).

F. Badoud; E. Grata; L. Perrenoud; M. Saugy; S. Rudaz; J.-L. Veuthey

2010-01-01

424

Gas-Liquid-Solid Phase Transition Model for Two-Dimensional Nanocrystal Self-Assembly on Graphite  

E-print Network

Gas-Liquid-Solid Phase Transition Model for Two-Dimensional Nanocrystal Self-Assembly on Graphite. Introduction The assembly of nanocrystals from solution into ordered arrays is a promising approach toward of alkane hair which lubricates the interface between the nanocrystal and the graphite; high mobility

425

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

426

Measurement of serum lamotrigine by high performance liquid chromatography using a phenyltriazine as internal standard.  

PubMed

Lamotrigine, an anti-epileptic drug with a phenyltriazine molecular structure, is commonly measured for therapeutic drug monitoring purposes by high performance liquid chromatography (HPLC) or gas liquid chromatography (GLC). A convenient internal standard is the structurally related phenyltriazine compound BWA725C previously obtainable from the Wellcome Foundation, UK. Irsogladine is also structurally similar to lamotrigine and was therefore tested as a possible replacement for BWA725C. A GLC procedure with thermionic detection (NPD) has been utilized routinely for lamotrigine in our drug monitoring facility. Irsogladine was unsuitable, however, because the retention times of irsogladine and a co-prescribed drug, carbamazepine, were very similar. An HPLC method utilizing a Prodigy Phenomenex ODS3 column performed well using either of the internal standards. The pH of the mobile phase had a distinct impact on the spectra of lamotrigine and BWA725C. A mobile phase at pH 3, with detection at 225 nm was required to effectively resolve lamotrigine from sulthiame and irsogladine from phenobarbitone. Comparison of the HPLC and the existing GLC method with routine patient specimens (n = 43) gave an equation, y = 0.9382x + 0.8238, R(2) = 0.9862. Irsogladine was found to be a suitable internal standard for an HPLC analysis of lamotrigine. PMID:21344674

Madhavaram, H; Woollard, G A; Couch, R A F

2012-02-01

427

Combining Hydrophilic Interaction Chromatography (HILIC) and Isotope Tagging for Off-Line LC-NMR Applications in Metabolite Analysis  

PubMed Central

The complementary use of liquid chromatography (LC) and nuclear magnetic resonance (NMR) has shown high utility in a variety of fields. While the significant benefit of spectral simplification can be achieved for the analysis of complex samples, other limitations remain. For example, 1H LC-NMR suffers from pH dependent chemical shift variations, especially during urine analysis, owing to the high physiological variation of urine pH. Additionally, large solvent signals from the mobile phase in LC can obscure lower intensity signals and severely limit the number of metabolites detected. These limitations, along with sample dilution, hinder the ability to make reliable chemical shift assignments. Recently, stable isotopic labeling has been used to detect quantitatively specific classes of metabolites of interest in biofluids. Here we present a strategy that explores the combined use of two-dimensional hydrophilic interaction chromatography (HILIC) and isotope tagged NMR for the unambiguous identification of carboxyl containing metabolites present in human urine. The ability to separate structurally related compounds chromatographically, in off-line mode, followed by detection using 1H-15N 2D HSQC (two-dimensional heteronuclear single quantum coherence) spectroscopy, resulted in the assignment of low concentration carboxyl-containing metabolites from a library of isotope labeled compounds. The quantitative nature of this strategy is also demonstrated. PMID:24860727

Appiah-Amponsah, Emmanuel; Owusu-Sarfo, Kwadwo; Gowda, G.A. Nagana; Ye, Tao; Raftery, Daniel

2013-01-01

428

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.

2011-05-26

429

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.

Yu, Julie

2007-01-01

430

Modulation of mobile phase composition in flow-injection\\/sequential-injection chromatography exploiting multisyringe flow analysis  

Microsoft Academic Search

In this paper, a time-based multicommutated flow system is proposed for appropriate selection and modulation of mobile phase\\u000a composition in flow-injection (FI)\\/sequential-injection (SI) chromatography. The novel flow assembly involves the on-line\\u000a coupling of a short monolithic reversed-phase chromatographic column with a multisyringe flow injection set-up furnished with\\u000a a set of solenoid valves. The proposed hyphenated technique was applied to the

Mailen Fernández; Manuel Miró; Hilda M. González; Víctor Cerdà

2008-01-01

431

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

432

Analysis of isothiazolinones in environmental waters by gas chromatography–mass spectrometry  

Microsoft Academic Search

This paper describes an analytical method for the determination of five biocides of isothiazolinone type (2-methyl-3-isothiazolinone (MI), 5-chloro-2-methyl-3-isothiazolinone (CMI), 1,2-benzisothiazolinone (BIT), 2-octyl-3-isothiazolinone (OI), 4,5-dichloro-2-octyl-3-isothiazolinone (DCOI)) in environmental waters. The method is based on pre-concentration of the analytes by solid-phase extraction onto a mixture of a polymeric material and RP-C18 material and subsequent determination by gas chromatography–mass spectrometry (GC–MS). One of

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

2007-01-01

433

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

434

Ion exchange chromatography and mass spectrometric methods for analysis of cadmium-phytochelatin (II) complexes.  

PubMed

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

Rodrigo, Miguel Angel Merlos; Cernei, Natalia; Kominkova, Marketa; Zitka, Ondrej; Beklova, Miroslava; Zehnalek, Josef; Kizek, Rene; Adam, Vojtech

2013-04-01

435

Analysis of polyaromatic hydrocarbon mixtures with laser ionization gas chromatography/mass spectrometry  

SciTech Connect

Excimer laser induced multiphoton ionization has been utilized for ion generation in capillary gas chromatography/mass spectrometry and the technique applied to the separation and detection of polyaromatic hydrocarbons. Detection limits as low as 200 fg and linearity over a range of 5 x 10/sup +4/ were obtained for the polyaromatic hydrocarbons examined. Multiphoton ionization mass spectra were dominated by parent ions. Selective ionization based upon small differences in ionization potentials has been demonstrated for coeluting chrysene and triphenylene. Instrumental parameters have been investigated to assess improvements in sensitivity.

Rhodes, G.; Opsal, R.B.; Meek, J.T.; Reilly, J.P.

1983-02-01

436

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

437

Advanced proteomic liquid chromatography  

PubMed Central

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. PMID:22840822

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

2012-01-01

438

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

439

Fingerprint analysis of Hibiscus mutabilis L. leaves based on ultra performance liquid chromatography with photodiode array detector combined with similarity analysis and hierarchical clustering analysis methods  

PubMed Central

Background: A method for chemical fingerprint analysis of Hibiscus mutabilis L. leaves was developed based on ultra performance liquid chromatography with photodiode array detector (UPLC-PAD) combined with similarity analysis (SA) and hierarchical clustering analysis (HCA). Materials and Methods: 10 batches of Hibiscus mutabilis L. leaves samples were collected from different regions of China. UPLC-PAD was employed to collect chemical fingerprints of Hibiscus mutabilis L. leaves. Results: The relative standard deviations (RSDs) of the relative retention times (RRT) and relative peak areas (RPA) of 10 characteristic peaks (one of them was identified as rutin) in precision, repeatability and stability test were less than 3%, and the method of fingerprint analysis was validated to be suitable for the Hibiscus mutabilis L. leaves. Conclusions: The chromatographic fingerprints showed abundant diversity of chemical constituents qualitatively in the 10 batches of Hibiscus mutabilis L. leaves samples from different locations by similarity analysis on basis of calculating the correlation coefficients between each two fingerprints. Moreover, the HCA method clustered the samples into four classes, and the HCA dendrogram showed the close or distant relations among the 10 samples, which was consistent to the SA result to some extent. PMID:23930008

Liang, Xianrui; Ma, Meiling; Su, Weike

2013-01-01

440

Purification of fire derived markers for lg scale isotope analysis C) using high performance liquid chromatography (HPLC)  

E-print Network

performance liquid chromatography (HPLC) Merle Gierga a, , Maximilian P.W. Schneider b , Daniel B. Wiedemeier isolated using high performance liquid chromatography (HPLC) and con- verted to CO2 via wet chemical

Gilli, Adrian

441

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

442

Comprehensive sample analysis using high performance liquid chromatography with multi-detection.  

PubMed

Herein we assess the separation space offered by a liquid chromatography system with an optimised uni-dimensional separation for the determination of the key chemical entities in the highly complex matrix of a tobacco leaf extract. Multiple modes of detection, including UV-visible absorbance, chemiluminescence (acidic potassium permanganate, manganese(IV), and tris(2,2'-bipyridine)ruthenium(III)), mass spectrometry and DPPH radical scavenging were used in an attempt to systematically reduce the data complexity of the sample whilst obtaining a greater degree of molecule-specific information. A large amount of chemical data was obtained, but several limitations in the ability to assign detector responses to particular compounds, even with the aid of complementary detection systems, were observed. Thirty-three compounds were detected via MS on the tobacco extract and 12 out of 32 compounds gave a peak height ratio (PHR) greater than 0.33 on one or more detectors. This paper serves as a case study of these limitations, illustrating why multidimensional chromatography is an important consideration when developing a comprehensive chemical detection system. PMID:24216214

Pravadali, Sercan; Bassanese, Danielle N; Conlan, Xavier A; Francis, Paul S; Smith, Zoe M; Terry, Jessica M; Shalliker, R Andrew

2013-11-25

443

Purification and analysis of human alpha1-antitrypsin concentrate by a new immunoaffinity chromatography.  

PubMed

Alpha1-antitrypsin is a kind of plasma protein that requires a sequence of different fractionation steps to get generally. To report an effective process for isolating and purifying alpha1-antitrypsin from Cohn Fraction IV based upon a new immunoaffinity chromatography medium, named "Alpha-1 Antitrypsin Select," characterization of alpha1-antitrypsin (?1-AT) was performed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), Western blot, and tandem mass spectroscopy. Total protein content was determined by the method of Bradford under visible light absorption at 595 nm. Pretreatment process and the immunoaffinity chromatography step achieved a 60.35 ± 1.39% yield. Thus, an overall 71.68 ± 1.32 fold increase in purity and a 41.88 ± 6.98% yield were obtained from plasma. The ?1-AT had a specific activity of about 1.00-1.05 PU/mg. This technique will develop an effective process for isolating and purifying, with high purity and specific activity, alpha1-antitrypsin from Cohn Fraction IV or human whole plasma, which could be an efficient and scaled-up method for alpha1-antitrypsin products purification. PMID:24279822

Zhang, Xuejun; Hou, Yiling; Ding, Xiang; Ye, Shengliang; Cao, Haijun; Wang, Zongkui; Du, Xi; Xie, Yi-wu; Li, Changqing

2014-10-01

444

Analysis of phospholipids in rat brain using liquid chromatography-mass spectrometry.  

PubMed

The brain is a lipid-rich organ containing complex polar lipids including phospholipids (PLs) and sphingolipids. These lipids are involved in the structure and function of cell membranes in the brain. We developed a fast and efficient liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to quantify five different classes of PLs [Choline glycerophospholipid (consists of phosphatidyl choline and plasmenyl choline in these samples), ethanolamine glycerophospholipid (consist of phosphatidyl ethanolamine and plasmenyl ethanolamine in these samples), phosphatidyl serine, phosphatidyl inositol, and sphingomyelin] in the brain tissues of 80-day-old Wistar rats. The PLs were extracted from rat brain using chloroform/methanol/water. After separation using a hydrophilic high performance liquid chromatography column, PL-class-specific fragmentation (head group identification) with a tandem mass spectrometer in positive ion mode was utilized to measure changes in the relative concentration of the five PL classes. The advantage of this approach was its improved specificity over previously reported LC-MS methods. The method had good repeatability (coefficient of variation 3-9%, excluding phosphatidyl inositol) and recovery (92-103%) and compared well with more laborious traditional methods. PMID:19856008

Norris, Carmen; Fong, Bertram; MacGibbon, Alastair; McJarrow, Paul

2009-11-01

445

Comprehensive two-dimensional gas chromatography combined to multivariate data analysis for detection of disease-resistant clones of Eucalyptus.  

PubMed

In this paper it is reported the use of the chromatographic profiles from volatile fractions of plant clones - in this case, hybrids of Eucalyptus grandis×Eucalyptus urophylla - to determine specimens susceptible to rust disease. The analytes were isolated by headspace solid phase microextraction (HS-SPME) and analyzed by comprehensive two-dimensional gas chromatography combined to fast quadrupole mass spectrometry (GC×GC-qMS). Parallel Factor Analysis (PARAFAC) was employed for estimate the correlation between the chromatographic profiles and resistance against Eucalyptus rust, after preliminary variable selection performed by Fisher ratio analysis. The proposed method allowed the differentiation between susceptible and non-susceptible clones and determination of three resistance biomarkers. This approach can be a valuable alternative for the otherwise time-consuming and labor-intensive methods commonly used. PMID:24148519

Hantao, Leandro Wang; Toledo, Bruna Regina; Ribeiro, Fabiana Alves de Lima; Pizetta, Marilia; Pierozzi, Caroline Geraldi; Furtado, Edson Luiz; Augusto, Fabio

2013-11-15

446

A Metabonomic Analysis of Serum from Rats Treated with Ricinine Using Ultra Performance Liquid Chromatography Coupled with Mass Spectrometry  

PubMed Central

A metabonomic approach based on ultra performance liquid chromatography coupled with mass spectrometry (UPLC/MS) was used to study the hepatotoxicity of ricinine in rats. Potential biomarkers of ricinine toxicity and toxicological mechanism were analyzed by serum metabonomic method. The significant differences in the metabolic profiling of the control and treated rats were clear by using the principal components analysis (PCA) of the chromatographic data. Significant changes of metabolite biomarkers like phenylalanine, tryptophan, cholic acid, LPC and PC were detected in the serum. These biochemical changes were related to the metabolic disorders in amino acids and phospholipids. This research indicates that UPLC/MS-based metabonomic analysis of serum samples can be used to predict the hepatotoxicity and further understand the toxicological mechanism induced by ricinine. This work shows that metabonomics method is a valuable tool in drug mechanism study. PMID:24618672

Peng, Jing; Cai, Shuang; Wang, Lin; Zhao, Nan; Zhang, Ting-jian; Chen, Zai-xing; Meng, Fan-hao

2014-01-01

447

Identification and quantitative analysis of cytokinins from shoot apices of Mercurialis ambigua by gas chromatography-Mass spectrometry computer system.  

PubMed

This paper describes the identification and quantitative analysis of cytokinins from natural sources (150-500 g fresh weight) at the submicrogram level. It summarizes an improved purification procedure with high resolution power that permits the detection of Trimethylsilylderivatives by gas chromatography-mass spectrometry. A comparison of the intensity of a characteristic ion in the mass spectrum of suitable standard (5 ?g) and theintensity of the same ion in the mass spectrum of the extraction product permitted precise quantitative analysis. The method has been used to determine zeatin, trans- and cis-ribosylzeatin, and ?(2)-isopentenyladenosine concentrations in extracts from female and monoecious Mercurialis ambigua apices. It has been proved that differences appear in the endogenous cytokinin pools of monoecious and female individuals. PMID:24408681

Dauphin, B; Teller, G; Durand, B

1979-01-01

448

Gas Chromatography Analysis with Olfactometric Detection (GC-O) as a Useful Methodology for Chemical Characterization of Odorous Compounds  

PubMed Central

The gas chromatography-olfactometry (GC-O) technique couples traditional gas chromatographic analysis with sensory detection in order to study complex mixtures of odorous substances and to identify odor active compounds. The GC-O technique is already widely used for the evaluation of food aromas and its application in environmental fields is increasing, thus moving the odor emission assessment from the solely olfactometric evaluations to the characterization of the volatile components responsible for odor nuisance. The aim of this paper is to describe the state of the art of gas chromatography-olfactometry methodology, considering the different approaches regarding the operational conditions and the different methods for evaluating the olfactometric detection of odor compounds. The potentials of GC-O are described highlighting the improvements in this methodology relative to other conventional approaches used for odor detection, such as sensoristic, sensorial and the traditional gas chromatographic methods. The paper also provides an examination of the different fields of application of the GC-O, principally related to fragrances and food aromas, odor nuisance produced by anthropic activities and odorous compounds emitted by materials and medical applications. PMID:24316571

Brattoli, Magda; Cisternino, Ezia; Dambruoso, Paolo Rosario; de Gennaro, Gianluigi; Giungato, Pasquale; Mazzone, Antonio; Palmisani, Jolanda; Tutino, Maria

2013-01-01

449

Retention mechanism assessment and method development for the analysis of iohexol and its related compounds in hydrophilic interaction liquid chromatography.  

PubMed

Hydrophilic interaction liquid chromatography (HILIC) has emerged in recent years as a valuable alternative to reversed-phase liquid chromatography in the analysis of polar compounds. Research in HILIC is divided into two directions: the assessment of the retention mechanism and retention behavior, and the development of HILIC methods. In this work, four polar neutral analytes (iohexol and its related compounds A, B, and C) were analyzed on two silica and two diol columns in HILIC mode with the aim to investigate thoroughly the retention mechanisms and retention behavior of polar neutral compounds on these four columns. The adsorption and partition contribution to the overall HILIC retention mechanism was investigated by fitting the retention data to linear (adsorption and partition) and nonlinear (mixed-retention and quadratic) theoretical models. On the other hand, the establishment of empirical second-order polynomial retention models on the basis of D-optimal design made possible the estimation of the simultaneous influence of several mobile-phase-related factors. Furthermore, these models were also used as the basis for the application of indirect modeling of the selectivity factor and a grid point search approach in order to achieve the optimal separation of analytes. After the optimization goals had been set, the grids were searched and the optimal conditions were identified. Finally, the optimized method was subjected to validation. PMID:24752695

Jovanovi?, Marko; Raki?, Tijana; Jan?i?-Stojanovi?, Biljana; Ivanovi?, Darko; Medenica, Mirjana

2014-07-01

450

Gas chromatography analysis with olfactometric detection (GC-O) as a useful methodology for chemical characterization of odorous compounds.  

PubMed

The gas chromatography-olfactometry (GC-O) technique couples traditional gas chromatographic analysis with sensory detection in order to study complex mixtures of odorous substances and to identify odor active compounds. The GC-O technique is already widely used for the evaluation of food aromas and its application in environmental fields is increasing, thus moving the odor emission assessment from the solely olfactometric evaluations to the characterization of the volatile components responsible for odor nuisance. The aim of this paper is to describe the state of the art of gas chromatography-olfactometry methodology, considering the different approaches regarding the operational conditions and the different methods for evaluating the olfactometric detection of odor compounds. The potentials of GC-O are described highlighting the improvements in this methodology relative to other conventional approaches used for odor detection, such as sensoristic, sensorial and the traditional gas chromatographic methods. The paper also provides an examination of the different fields of application of the GC-O, principally related to fragrances and food aromas, odor nuisance produced by anthropic activities and odorous compounds emitted by materials and medical applications. PMID:24316571

Brattoli, Magda; Cisternino, Ezia; Dambruoso, Paolo Rosario; de Gennaro, Gianluigi; Giungato, Pasquale; Mazzone, Antonio; Palmisani, Jolanda; Tutino, Maria

2013-01-01

451

Quantitative Analysis and Fingerprint Profiles for Quality Control of Fructus Schisandrae by Gas Chromatography: Mass Spectrometry  

PubMed Central

This paper describes a simple, rapid, and effective quality assessment method for Fructus Schisandrae by gas chromatography-mass spectrum (GC-MS). The method was established by using specific lignan fingerprint profiles and quantitation of characteristic compounds in this herbal medicine. The GC-MS fingerprints of 15 batches of Schisandra samples from different regions of China showed similar lignan profiles. Five peaks were selected as characteristic peaks, and all of these were identified by using GC-MS techniques. The relative retention times of these characteristic peaks in the GC-MS fingerprint were established as an important parameter for identification of Schisandra samples. Meanwhile, relative peak areas may be a feasible approach to discriminate the S. chinensis and S. sphenanthera. Finally, these pharmacologically active constituents in the titled plant, schisandrins A–C and schizandrols A and B, were quantitatively determined using a validated GC-MS method. PMID:24574919

Xia, Yong-Gang; Yang, Bing-You; Liang, Jun; Yang, Qi; Wang, Di; Kuang, Hai-Xue

2014-01-01

452

Analysis of lipophilic pigments from a phototrophic microbial mat community by high performance liquid chromatography  

NASA Technical Reports Server (NTRS)

As assay for lipophilic pigments in phototrophic microbial mat communities using reverse phase-high performance liquid chromatography was developed which allows the separation of 15 carotenoids and chloropigments in a single 30 min program. Lipophilic pigments in a laminated mat from a commercial salina near Laguna Guerrero Negro, Baja California Sur, Mexico reflected their source organisms. Myxoxanthophyll, echinenone, canthaxanthin, and zeaxanthin were derived from cyanobacteria; chlorophyll c, and fucoxanthin from diatoms; chlorophyll a from cyanobacteria and diatoms; bacteriochlorophylls a and c, bacteriophaeophytin a, and gamma-carotene from Chloroflexus spp.; and beta-carotene from a variety of phototrophs. Sensitivity of detection was 0.6-6.1 ng for carotenoids and 1.7-12 ng for most chloropigments. This assay represents a significant improvement over previous analyses of lipophilic pigments in microbial mats and promises to have a wider application to other types of phototrophic communities.

Palmisano, A. C.; Cronin, S. E.; Des Marais, D. J.

1988-01-01

453

[Detection of diacetylmorphine (heroin) use by thin-chromatography analysis of urine].  

PubMed

The proof of diacetylmorphine (heroin) application is based on the identification of its specific metabolite 6-monoacetylmorphine simultaneously detected with the main metabolite morphine in human urine. Codeine is another morphine derivative appearing in cases of diacetylmorphine abuse; it can be considered a metabolite of 6-acetylcodeine, a typical impurity found in raw heroin. An analytical procedure for detection of the mentioned morphine basesin urine is presented, including a screening method. A careful extraction method is required for 6-monoacetylmorphine. To classify it into the code system of the screening, its properties are expressed by a threecomponent code. Subsequent identity confirmation of the mentioned bases by means of thin layer chromatography uses mobile phases, in which optimal separation effects are achieved, even in the presence of nicotine or caffeine and its metabolites theobromine and theophylline. Circumstances of 6-monoacetylmorphine discovery in urine are discussed. PMID:9471732

Vecerková, J

1997-08-01

454

Biointeraction Analysis of Immobilized Antibodies and Related Agents by High-Performance Immunoaffinity Chromatography  

PubMed Central

Summary A method is described based on high-performance immunoaffinity chromatography for examining the interactions of immobilized antibodies or related binding agents with their targets. It is shown how this method can be used to obtain information on the binding, elution and regeneration kinetics of immobilized binding agents, such as those used with immunoaffinity supports. The theory behind this approach is briefly described and it is demonstrated how both the kinetic and thermodynamic properties of a biointeraction can be determined experimentally through this method. Several applications are used to illustrate this technique, including antibody-antigen interactions and the binding of aptamers with their targets in the presence of silica-based supports. The same approach can be adapted for use with other types of targets, binding agents and support materials. PMID:21907805

Pfaunmiller, Erika; Moser, Annette C.; Hage, David S.

2011-01-01

455

A micro gas chromatography column with a micro thermal conductivity detector for volatile organic compound analysis  

NASA Astrophysics Data System (ADS)

In this paper, a micro gas chromatography (?GC) system contained a ?GC column and a micro thermal conductivity detector (?TCD) was proposed. In order to reduce the volume of the system, some micro heaters were integrated on the surface and backside of the GC column, which could provide a robust temperature programming capability and rapidly increase the temperature of the ?GC column. In addition, a silicon-glas