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1

Gas-liquid chromatography in lunar organic analysis.  

NASA Technical Reports Server (NTRS)

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

Gehrke, C. W.

1972-01-01

2

Analysis of quality of aviation lubricating oils by means of liquid and gas-liquid chromatography  

SciTech Connect

The authors examine the basic methodological aspects of chromatographic analysis of the quality of oils for aircraft gas turbine engines, and certain relationships in oil aging that have been established on this basis. A commercial ester (designated PEE) was selected for investigation of pentaerythritol and C/sub 5/-C/sub 9/ synthetic fatty acids (SFA) which serves as the synthetic base stock for a number of aviation oils. The changes in PEE composition upon oxidation, with or without additives, were evaluated by means of gas-liquid chromatography in a Tsvet-100 chromatograph with a flame ionization detector. The results from examination of the original and oxidized PEE samples by means of gas and liquid chromatography are presented.

Kholostova, G.G.; Bakunin, V.N.; Shimonaev, G.S.

1987-01-01

3

Simultaneous Extraction and Derivatization of Carbohydrates from Green Plant Tissues for Analysis by Gas–Liquid Chromatography  

Microsoft Academic Search

Simultaneous extraction and derivatization of carbohydrates was performed by mixing dry ground plant tissue with derivatization reagents in pyridine; trimethylsilyl derivatives were analyzed by gas–liquid chromatography. This “direct analysis” was compared to analysis of samples prepared by exhaustive ethanol extraction of the same ground plant tissues. Comparisons included leaf blades from apple, grape, corn, and tomato and leaf blade, petiole,

John G. Streeter; C. Elliott Strimbu

1998-01-01

4

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

Microsoft Academic Search

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

B. M. Craig; N. L. Murty

1959-01-01

5

Mixed Stationary Liquid Phases for Gas-Liquid Chromatography.  

ERIC Educational Resources Information Center

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

Koury, Albert M.; Parcher, Jon F.

1979-01-01

6

A method for the simultaneous analysis of unconjugated and glycine-conjugated bile acids by capillary gas-liquid chromatography.  

PubMed

A method for the simultaneous analysis of unconjugated and glycine-conjugated bile acids by means of capillary gas-liquid chromatography without need for prior deconjugation is described. The method involves: i) the use of an aluminum-clad fused-silica capillary column coated with a very thin film (0.1 micron) of a highly thermostable bonded and crosslinked methyl polysiloxane, and ii) the analysis of the bile acids as their methyl ester-dimethylethylsilyl ether derivatives. This method, used to separate the major free and glycine-conjugated bile acids from human gall bladder bile, should be applicable for the analysis of other biological fluids. PMID:2615572

Iida, T; Itoh, T; Hagiwara, K; Chang, F C; Goto, J; Nambara, T

1989-12-01

7

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

Microsoft Academic Search

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

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

1971-01-01

8

Analysis of cis - and trans -fatty acid isomers in hydrogenated and refined vegetable oils by capillary gas-liquid chromatography  

Microsoft Academic Search

For quantitation ofcis- andtrans-fatty acid isomers, infrared (IR) spectroscopy, gas-liquid chromatography (GLC) on highly polar stationary phases or the\\u000a combination (GLC-IR) may be used. IR offers the advantage of simplicity and speed, but the lower determination limit of 5%\\u000a and the lack of detailed information limit its use. Detailed fatty acid information, required for, e.g., food-labeling purposes,\\u000a can only be

G. S. M. J. E. Duchateau; H. J. van Oosten; M. A. Vasconcellos

1996-01-01

9

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

Code of Federal Regulations, 2014 CFR

...2014-04-01 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...

2014-04-01

10

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

11

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

Code of Federal Regulations, 2010 CFR

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

2010-04-01

12

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

13

Discrimination between oral streptococci by pyrolysis gas-liquid chromatography.  

PubMed Central

Washed organisms, including strains of Streptococcus mitior, S. mutans, and S. sanguis, were examined by curie-point pyrolysis gas-liquid chromatography. A linear discriminant function based upon three items from the output data was adequate for segregating the strains according to species. Strains with intermediate properties were also encountered. Sources of variability in cultures were evaluated, chromatographic performance was maintained throughout the investigation, and matching performance from a duplicate pair of chromatographic columns was demonstrated. PMID:623471

Stack, M V; Donoghue, H D; Tyler, J E

1978-01-01

14

Faster identification of mycobacteria using gas liquid and thin layer chromatography  

Microsoft Academic Search

Gas liquid chromatography (GLC) and thin layer chromatography (TLC) analysis of cell wall content was used for identification of mycobacteria isolated in primary cultures. GLC permitted determination of the fatty acid and alcohol profiles ofMycobacterium simiae andMycobacterium marinum and detection of a peak inMycobacterium ulcerans formerly described forMycobacterium malmoense. Using the data obtained to fill some of the gaps in

J. J. Parez; M. Fauville-Dufaux; J. L. Dossogne; E. de Hoffmann; F. Pouthier

1994-01-01

15

An uncooked vegan diet shifts the profile of human fecal microflora: computerized analysis of direct stool sample gas-liquid chromatography profiles of bacterial cellular fatty acids.  

PubMed Central

The effect of an uncooked extreme vegan diet on fecal microflora was studied by direct stool sample gas-liquid chromatography (GLC) of bacterial cellular fatty acids and by quantitative bacterial culture by using classical microbiological techniques of isolation, identification, and enumeration of different bacterial species. Eighteen volunteers were divided randomly into two groups. The test group received an uncooked vegan diet for 1 month and a conventional diet of mixed Western type for the other month of the study. The control group consumed a conventional diet throughout the study period. Stool samples were collected. Bacterial cellular fatty acids were extracted directly from the stool samples and measured by GLC. Computerized analysis of the resulting fatty acid profiles was performed. Such a profile represents all bacterial cellular fatty acids in a sample and thus reflects its microflora and can be used to detect changes, differences, or similarities of bacterial flora between individual samples or sample groups. GLC profiles changed significantly in the test group after the induction and discontinuation of the vegan diet but not in the control group at any time, whereas quantitative bacterial culture did not detect any significant change in fecal bacteriology in either of the groups. The results suggest that an uncooked extreme vegan diet alters the fecal bacterial flora significantly when it is measured by direct stool sample GLC of bacterial fatty acids. PMID:1482187

Peltonen, R; Ling, W H; Hänninen, O; Eerola, E

1992-01-01

16

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

USGS Publications Warehouse

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

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

1977-01-01

17

Analysis of therapeutic and commonly abused drugs in serum and urine by gas-liquid chromatography using a photoionization detector.  

PubMed

A simple, rapid and sensitive gas chromatographic procedure using the photoionization detector (PID) was developed for the detection and quantitation of several drugs in serum and urine. In order to evaluate the performance of the PID, the results were compared with those of the flame-ionization detector (FID). The data indicate that the PID is 8-16 times more sensitive than the FID for the drugs studied in the barbiturate group. Excellent reproducibility was found for samples quantitated with the PID on a routine basis. The PID and FID produced statistically similar results on extracted serum samples. The correlation coefficient was 0.99. The PID also produced chromatograms with less background than those obtained with the FID for many extracted serum samples. The advantages of the PID for drug analysis in biological fluids include simplicity of operation, lack of solvent response, universal drug response, non-destructive character and stability. PMID:44717

Jaramillo, L F; Driscoll, J N

1979-12-30

18

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

19

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

Code of Federal Regulations, 2011 CFR

...DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Laboratory Instruments § 862.2250 Gas liquid chromatography system for clinical use. (a)...

2011-04-01

20

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

PubMed

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

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

1977-01-01

21

Fecal short-chain fatty acid (SCFA) analysis by capillary gas-liquid  

Microsoft Academic Search

A new method is described for short-chain fatty acid (SCFA) analysis in stool samples. After sample purification by acid vacuum transfer and concentration by alkaline freeze- drying, SCFAs were measured by gas-liquid chromatography using a capillary column. Peak resolution and reproducibility were superior to SCFA analysis on a conventional glass column. With this new technique SCFA were quantitated in stool

Wolfgang M Scheppach; Claudia E Fabian; Heinrich W Kasper

22

Analysis of C 18:1 cis and trans fatty acid isomers by the combination of gas-liquid chromatography of 4,4-dimethyloxazoline derivatives and methyl esters  

Microsoft Academic Search

Trans fatty acids in foods are usually analyzed by gas-liquid chromatography (GLC) of fatty acid methyl esters (FAME). However,\\u000a this method may produce erroneously low values because of insufficient separation between cis and trans isomers. Separation can be optimized by preceding silver-ion thin-layer chromatography (Ag-TLC), but this is laborious. We\\u000a have developed an efficient method for the separation of 18-carbon

Antti Aro; Truus Kosmeijer-Schuil; Peter van de Bovenkamp; Paul Hulshof; Peter Zock; Martijn B. Katan

1998-01-01

23

Resolution of diacylglycerol moieties of natural glycerophospholipids by gas-liquid chromatography on polar capillary columns.  

PubMed

A rapid and practical method has been developed for the gas-liquid chromatographic determination of the sn-1,2-diacylglycerol moieties of natural glycerophospholipids using polar wall-coated open tubular columns. The method gives complete resolution and quantitative estimates for all species according to molecular weight and degree of unsaturation, including stearoyl docosahexaenoylglycerol and related polyunsaturates. For this purpose the sn-1,2-diacylglycerols are obtained from the glycerophospholipids by hydrolysis with phospholipase C and are converted into the trimethylsilyl or tertiary-butyldimethylsilyl ethers. The silyl ethers are separated by gas-liquid chromatography on the capillary glass columns coated with a polar cyanopropylsiloxane polymer, in the temperature range 175-250 degrees C, using hydrogen as the carrier gas. Practical applications of the method are illustrated by analyses of the sn-1,2-diacylglycerol moieties of the phosphatidylcholines of soybean phosphatides, egg yolk, and rat liver. The method of analysis is applicable to other classes of glycerophospholipids and the total time requirements for the analysis of any one phospholipid class are comparable to those for a fatty acid analysis. PMID:6889454

Myher, J J; Kuksis, A

1982-06-01

24

Application of gas-liquid chromatography and high-performance liquid chromatography to the analysis of trace amounts of salicylic acid, acetylsalicylic anhydride and acetylsalicylsalicylic acid in aspirin samples and aspirin formulations.  

PubMed

The gas-liquid chromatographic (GLC) determination of salicylic acid (SA) in 12 commercial acetylsalicylic acid (aspirin, ASA) samples and 12 ASA formulations is reported. The GLC determination of SA as an impurity in ASA, utilising methylation with methyl iodide in the presence of potassium carbonate, requires a column chromatographic separation of SA prior to derivatization. Trace amounts of SA in ASA have also been determined by high-performance liquid chromatography (HPLC) on a Sil-X-I adsorption column using light petroleum-ethyl acetate-acetic acid as the mobile phase. Acetylsalicylic anhydride (ASN) and acetylsalicylsalicylic acid (ASSA) were determined by HPLC on a reversed-phase C18 column with water-methanol mixtures as the mobile phase. GLC was also applied to the determination of ASN as an impurity in ASA formulations. PMID:977701

Ali, S L

1976-11-01

25

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...

26

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

Microsoft Academic Search

By critically selecting optimum operating conditions, quantitative gas-liquid chromatography of triglycerides has been extended\\u000a to molecules containing substantial amounts of C20, C22, and C24 fatty acids. The triglycerides of four erucic acid oils (water cress, rapessed, nasturtium, andLunaria annua) and two fully hydrogenated fish oils (menhaden and tuna) have been quantitatively analyzed by this technique. The average\\u000a fatty acid chain

R. D. Harlow; Carter Litchfield; Raymond Reiser

1966-01-01

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

Coupled assay of sphingomyelin and ceramide molecular species by gas liquid chromatography.  

PubMed

This study reports a single-step analysis of the molecular species of endogenous ceramides and of the ceramide moiety of sphingomyelins in biological samples, using gas liquid chromatography (GLC). Silylated sphingomyelins were quantitatively converted to monosilylated ceramide upon injection into GLC, whereas the free ceramides were di-silylated on the primary and secondary alcohol function, as confirmed by mass spectrometry. The reproducible shift of the retention times between the mono- and di-silylated derivatives enables simultaneous quantification of the variety of sphingomyelin and ceramide molecular species. Overlapping diacylglycerols were first removed by a mild alkaline treatment of the lipid extract. The lowest detection limit (5 pmol) did not allow for identification of free ceramides in human plasma, but 17 molecular species of ceramides derived from sphingomyelins were quantified, from NC16:0 up to NC24:1. By contrast, three major free ceramides (NC16:0, NC24:0, and NC24:1) were quantified in HEPG2 and Chinese hamster ovary (CHO) cells. Upon induction of apoptosis in CHO cells by C6-ceramide, we could follow the disappearance of the C6-ceramide, its partial conversion to C6-sphingomyelin, and the prominent increase of NC16:0 ceramide. Thus, our method represents a unique procedure of simultaneous analysis of sphingomyelin and ceramide molecular species able to monitor the variation of the different pools in biological samples. PMID:11893787

Vieu, Claude; Tercé, François; Chevy, Françoise; Rolland, Corinne; Barbaras, Ronald; Chap, Hugues; Wolf, Claude; Perret, Bertrand; Collet, Xavier

2002-03-01

29

gas-liquid chromatographic analysis (see footnote A~'kl1()wlo:dgmO:l1ts  

E-print Network

for the analysis offish. animal. and poul- try tissue for chlorinated pesticide residues. J. Assoc. OfT. Anal. 480. Assoc. OIT. Anal. Chern.. Wash.. D.C. PESTICIDE ANALYTICAL MANUAL. 1977. Gas-liquid chromatography. In Pesticide analytical manual. Vol. I. Chapter 3. U.S. Dep. H"'alth. Educ.. and Welfare. Food

30

Application of gas-liquid chromatography to the routine identification of nonfermenting gram-negative bacteria in clinical specimens.  

PubMed Central

A total of 430 strains of glucose-nonfermenting gram-negative bacteria representing 35 species were analyzed for their cellular fatty acid composition by gas-liquid chromatography (GLC). On the basis of qualitative differences in their cellular fatty acid composition, these bacteria could be divided into 19 distinct chromatographic groups. Eight Pseudomonas species, Achromobacter xylosoxidans, group Vd, and Agrobacterium radiobacter were identified from their fatty acid compositions alone. The other glucose-nonfermenting gram-negative bacterial species studied here, classified within nine distinct GLC groups, were easily recognized by using the GLC fatty acid analysis supplemented with a limited number of conventional biochemical tests. The results support the hypothesis that bacterial fatty acid composition is rather specific and that qualitative GLC fatty acid analysis can be adapted in the clinical laboratory either to provide additional criteria for differentiation of closely related groups or to serve as a rapid and highly reproducible method for their routine identification. PMID:2768442

Veys, A; Callewaert, W; Waelkens, E; Van den Abbeele, K

1989-01-01

31

Gas-liquid chromatography-mass spectrometry of trimethylsilyl ethers of bile alcohols.  

PubMed

This report describes the gas-liquid chromatography-mass spectrometry (GLC-MS) of the trimethylsilyl ethers of 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha-triol with mono- or dihydroxy substitution in the side chain. Compounds with 24- and 25-unsaturation in the side chain were also studied. The gas-liquid chromatographic separation of the different bile alcohols was carried out using 3% QF-1 and 1% HI-EFF 8BP as column packings. Both columns were useful in that the retention times of the trimethyl-silyl ethers of the various 5 beta-cholestanetetrols varied linearly with the position of the side-chain trimethylsiloxyl substituent. The major fragmentations in the GLC-MS of all bile alcohols tested were due to the trimethylsiloxyl side-chain substituent(s). A trimethylsiloxyl group at C-22 was the most effective in promoting side-chain fragmentation, followed, in order of decreasing effectiveness, by substituents at carbons 25, 23, 24, and 26. The side-chain fragments generally gave rise to one or two intense mass peaks and a series of weaker peaks, 90 mass units apart, owing to the loss of successive molecules of trimethylsilanol. Most 5 beta-cholestane-triols, -tetrols, and -pentols can be unequivocally identified by their strong side-chain fragmentation peaks, except for 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 26-tetrol, the trimethylsilyl ether of which exhibited very low intensity side-chain fragments. PMID:731130

Tint, G S; Dayal, B; Batta, A K; Shefer, S; Cheng, F W; Salen, G; Mosbach, E H

1978-11-01

32

Determination of polyamines in human blood by electron-capture gas-liquid chromatography.  

PubMed

The present work was undertaken to develop a sensitive and selective method for the estimation of putrescine, spermidine and spermine in human blood employing electron-capture gas--liquid chromatography. Polyamines were derivatized with heptafluorobutyric anhydride. The heptafluorobutyric derivatives of polyamines could be well resolved within 15 min under a temperature programme. The detection limit was 0.1 pmol for putrescine and cadaverine, and 0.02 pmol for spermidine and spermine. The method was applied to polyamine determinations in erythrocytes from human blood. For pre-separation of the polyamines from other compounds, a simple clean-up method utilizing an activated Permutit has been devised. Major interfering substances could be removed by the batchwise Permutit treatment. The mean values of spermidine and spermine concentrations, and the spermidine/spermine ratio in erythrocytes obtained from normal subjects (n = 11) were similar to reported values. The analytical procedure is thought to be applicable to various biological materials. PMID:6643636

Fujihara, S; Nakashima, T; Kurogochi, Y

1983-10-14

33

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

34

Studies on bile acids: The microquantitative separation of cellular bile acids by gas-liquid chromatography.  

PubMed

1. A method is described for the quantitative isolation of bile acids from cellular material. Homogenates of rat liver are freeze-dried and extracted exhaustively with 95% (v/v) ethanol containing 0.1% (v/v) of aq. ammonia (sp.gr. 0.88) and purified by anion-exchange chromatography on Amberlyst A-26. 2. The extracted bile acid conjugates are subjected to either of two hydrolytic procedures, one involving chemical and the other enzymic agents. A unique feature in this study is the introduction of an enzyme, a clostridial peptide-bond hydrolase, for the rapid cleavage of bile acid conjugates, replacing the classical drastic chemical hydrolysis with strong alkali. 3. After hydrolysis, free bile acids are methylated and converted into their trifluoroacetates for final determination by gas-liquid chromatography on a triple component column, FS-1265-SE30-NGS. 4. For the purpose of identification of peaks, bile acid methyl esters are converted into their trimethylsilyl ethers by allowing the methyl esters to react with a new and potent silyl donor, bis(trimethylsilyl)acetamide. 5. The technique affords us a means of studying the metabolism of bile acids at the cellular and subcellular levels in tissues. PMID:16742477

Okishio, T; Nair, P P; Gordon, M

1967-03-01

35

Ionic liquids as novel stationary phases in gas liquid chromatography: inverse or normal isotope effect?  

PubMed

The separation of deuterated and non-deuterated compounds in gas liquid partitioning chromatography (GLC) on silicone type stationary phase usually results in the inverse isotope effect. With ionic liquids (ILs) as stationary phase, however, this may show a totally different nature. The inverse isotope effect, in which heavier (deuterated) isotopic compounds (isotopologues) elute earlier, is to be expected when van der Waals (London) dispersion forces play a dominant role in the solute-stationary phase interaction. Such (apolar) interactions seem to play only a minor role when ILs are the stationary phases, leading to only a marginal inverse isotope effect, e.g. for the separation of 2,4,6-trichloroanisole and its [(2)H(5)]-isotopologue on 1,12-di(tripropylphosphonium) dodecane bis(trifluoromethansulfonyl) amide (commercialized as SLB-IL59, Supelco). Indeed, with the most polar stationary phase available (commercialized as SLB-IL111; Supelco), this separation showed a normal isotope effect. Further examples are presented and the nature of the isotope effect observed is discussed. PMID:23200305

Schmarr, Hans-Georg; Slabizki, Petra; Müntnich, Sabrina; Metzger, Carmen; Gracia-Moreno, Elisa

2012-12-28

36

Determination of organic substances with different boiling points in aqueous media by capillary gas-liquid chromatography  

Microsoft Academic Search

Studies were conducted on separation of organic substances with different boiling points and polarity when simultaneously\\u000a present in water by capillary gas-liquid chromatography on a Kristall 2000 m chromatograph. The effect of the column phase\\u000a and temperature conditions on the separation factor and component exit time was investigated. Column temperature programming\\u000a was used to reduce the component, especially heavy component,

E. A. Rogova; O. A. Roshchina; T. I. Samsonova; A. V. Genis

2009-01-01

37

Methyl mercaptan and dimethyl disulfide production from methionine by Proteus species detected by head-space gas-liquid chromatography.  

PubMed Central

Head-space gas-liquid chromatography and mass spectrometry were used to detect and identify products formed by Proteus vulgaris, P. mirabilis, P. morganii, and P. rettgeri from a defined medium supplemented with either phenylalanine, methionine, valine, leucine, histidine, lysine, ornithine, threonine, asparagine, aspartic acid, or tryptophan. In a detailed study of the products formed by 68 strains of Proteus spp. from L-methionine, the production of large amounts of both dimethyl disulfide and methyl mercaptan was found to be a characteristic of the genus. Both sulfur products appeared within a few hours of inoculation. Dimethyl disulfide was a more sensitive indicator of growth than the spectrometric determination of optical density. This suggests that it could be useful for the rapid, automated detection of any species of Proteus. PMID:332705

Hayward, N J; Jeavons, T H; Nicholson, A J; Thornton, A G

1977-01-01

38

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

SciTech Connect

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

Minus, D.D.

1996-02-01

39

Comparative studies on individual isomeric 18?1 acids in cow, goat, and ewe milk fats by low-temperature high-resolution capillary gas-liquid chromatography  

Microsoft Academic Search

The trans- as well as the cis-18?1 isomer profiles were established in cow, goat, and ewe cheese fats, with the assumption that these are representative\\u000a of the corresponding milks. Argentation thin-layer chromatography was combined with low-temperature high-resolution gas-liquid\\u000a chromatography on 100-m highly polar capillary columns, thus adding precision to earlier data for these species. Despite differences\\u000a in the absolute content

Dietz Precht; Joachim Molkentin; Frédéric Destaillats; Robert L. Wolff

2001-01-01

40

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

Microsoft Academic Search

Thirty-six Mycobacterium paratuberculosis isolates of bovine, caprine, and ovine origins were evaluated by using gas-liquid chromatography (GLC), thin-layer chromatography (TLC), and BACTEC 7H12 Middlebrook TB medium in an effort to more rapidly differentiate this group of organisms from other mycobacteria. Bacterial suspensions (0.1 ml) were inoculated by syringe into 7H12 broth containing 2 micrograms of mycobactin P per ml and

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

1987-01-01

41

Gas-Liquid Chromatographic Analysis of Indole-3-acetic Acid Myoinositol Esters in Maize Kernels 1  

PubMed Central

An improved method of fractionating the myoinositol esters of indoleacetic acid (IAA) from maize kernels by gas-liquid chromatography has been developed. Mass spectrometry was employed as an aid in identification of the esters. Maize kernels contain three groups of esters of IAA: (a) IAA myoinositols, (b) IAA myoinositol arabinosides, and (c) IAA myoinositol galactosides. Each group has three chromatographically distinguishable isomers. The glycosylinositols described are unique in that carbon 1 of the sugar is attached to the hydroxyl at C-5 of the myoinositol. PMID:16657535

Ueda, Minoru; Ehmann, Axel; Bandurski, Robert S.

1970-01-01

42

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

PubMed

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

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

2012-07-01

43

Differentiation of Escherichia coil and Aerobacter aerogenes by Gas Liquid Chromatography  

Microsoft Academic Search

Six isolates of Aerobacter aerogenes; one Pseudomonas aergenoidcs ; five Escherichia coli; one Escherichia freundii; and one Escherichia intermedia were obtained from different sources and classified according to Bergey's 5(anual. Cultures of each were prepared in heat- and vacuum-treated milk and incubated 30 hr at 35 C. An attempt was made to differentiate these species by gas chromatography (GLC) of

R. E. BAWDON; R. BASSETTE

44

The use of gas?liquid chromatography to determine the proportions of inositol isomers present as pentakis? and hexakisphosphates in alkaline extracts of soils  

Microsoft Academic Search

A method for determining the relative proportions of inositol isomers present in soil as their pentakis? and hexakisphosphate derivatives (IP5 + IP6) is presented. The method involves determination of the isomers as their hexakis?O?acetyl derivatives by gas?liquid chromatography. The only isomers detected in extracts of 4 soils were chiro?inositol, neo?inositol, myo?inositol and soyllo?to?inositol. Little variation in the relative proportions of

G. C. J. Irving; D. J. Cosgrove

1982-01-01

45

A comparison of gas–liquid chromatography, NMR spectroscopy and Raman spectroscopy for determination of the substituent content of general non-ionic cellulose ethers  

Microsoft Academic Search

This paper describes and compares three techniques that can be used to characterize the substituent content of hydroxypropylcellulose (HPC and L-HPC) and hydroxypropyl methylcellulose (HPMC): gas–liquid chromatography (GLC) with a BP1 column and FI detection, 13C-NMR spectroscopy of hydrolysed samples, and Raman spectroscopy. GLC and 13C-NMR spectroscopy both allow independent quantification of hydroxypropoxyl and methoxyl contents. 13C-NMR spectroscopy, though requiring

C. Alvarez-Lorenzo; R. A. Lorenzo-Ferreira; J. L. Gómez-Amoza; R. Mart??nez-Pacheco; C. Souto; A. Concheiro

1999-01-01

46

Separation and quantitative determination of the cerium group lanthanides by gas-liquid chromatography.  

PubMed

A gas chromatographic method is reported for the separation and subsequent quantitative determination of the cerium group lanthanides. The lanthanides (RE) are synergistically extracted from aqueous solution with the polyfluorinated beta-diketone 1,1,1,2,2,6,6,7,7,7-decafluoro-3,5-heptanedione, H(FHD), as ligand, and di-n-butylsulphoxide, DBSO, as neutral donor. The composition of the extracted species is reported to be RE(FHD)(3) .2DBSO. Thermogravimetric analysis of the complexes is reported. Analytical curves were prepared and found to be usable over the range of 0.1-10 mug of metal. Individual lanthanides were determined with 99.0 % recovery with a relative mean deviation of +/-2.0%. Mixture of lanthanides were analyzed with 101.2% recovery with a relative mean deviation of +/-2.2%. PMID:18961290

Burgett, C A; Fritz, J S

1973-04-01

47

Determination and speciation of mercury in a dental work-place by cold vapour atomic absorption spectrometry and gas-liquid chromatography.  

PubMed

Cold Vapour Atomic Absorption Spectrometry (CVAAS) and Gas-Liquid Chromatography (GLC) have been used for determination and speciation of mercury. Total mercury, methylmercury, ethylmercury and phenylmercury concentrations in urine samples taken from students and staff of a dental work-place were investigated. Air samples were also analyzed. Detection limits, as three times the standard deviation, and in units of ng analyte per ml urine were found to be 1.7, 12, 2.4 and 21 for total mercury, methylmercury chloride, ethylmercury chloride and phenylmercury chloride, respectively. PMID:3804555

Seçkin, M A; Aygün, S; Ataman, O Y

1986-01-01

48

Simultaneous quantitation of fatty acids, sterols and bile acids in human stool by capillary gas–liquid chromatography  

Microsoft Academic Search

A simple method for the simultaneous gas–liquid chromatographic quantitation of fatty acids, sterols and bile acids from human fecal samples is described. The various compounds are directly converted into the n-butyl ester-trimethylsilyl ether derivatives, without prior isolation from the stool. Under these conditions, fecal bile acid derivatives are well resolved from each other and from those of fecal fatty acids

Ashok K Batta; Gerald Salen; Priti Batta; G Stephen Tint; David S Alberts; David L Earnest

2002-01-01

49

Independent component analysis of the interface fluctuations of gas\\/liquid two-phase flow  

Microsoft Academic Search

It is important to study the interface fluctuations between the two phases in a gas\\/liquid flow to achieve an in-depth understanding of the mixture flow and subsequent optimization of industrial processes. This paper presents a study of the interface fluctuations between the gas and liquid phases in a pipeline. Experimental data are obtained from a gas\\/liquid two-phase flow rig through

Yanbin Xu; Huaxiang Wang; Ziqiang Cui; Feng Dong; Yong Yan

2009-01-01

50

Comparison of two gas–liquid chromatograph columns for the analysis of fatty acids in ruminant meat  

Microsoft Academic Search

Two gas–liquid chromatograph capillary columns for the analysis of fatty acids (FA) in ruminant fat are compared. Those columns are the CP-Sil 88 of 100m long with a highly polar stationary phase and the Omegawax 250 of 30m long with a stationary phase of intermediate polarity. Fatty acid methyl ester (FAME) patterns of branched-chain, cis and trans octadecenoate isomers, as

Susana P. Alves; Rui J. B. Bessa

2009-01-01

51

Study of individual trans - and cis -16?1 isomers in cow, goat, and ewe cheese fats by gas-liquid chromatography with emphasis on the trans -?3 isomer  

Microsoft Academic Search

Low-temperature gas-liquid chromatography (GLC) was applied to study the distribution profiles of isomeric trans-and cis-hexadecenoic acids in ruminant (cow, goat, and ewe) milk fat after their fractionation by argentation thin-layer chromatography\\u000a (Ag-TLC). The fat was extracted from cheeses (12 samples of each species), the most common foods made with goat and ewe milks.\\u000a The predominant trans-16?1 isomer is palmitelaidic acid

Frédéric Destaillats; Robert L. Wolff; Dietz Precht; Joachim Molkentin

2000-01-01

52

Characteristic Analysis of Gas\\/Liquid Two-Phase Flow Regimes Based on Wavelet Packet Entropy  

Microsoft Academic Search

The identification of flow regime is the basis for measuring flow parameters in two-phase flow accurately. Because of the complexity of phase interaction in gas-liquid two-phase flow, it is difficult to discern its flow regime objectively. In this paper, the 208 measured data from electrical resistance tomography (ERT) are arranged into series based on section to investigate the dynamic characteristics

Chun Fu; Feng Dong

2010-01-01

53

Gas-liquid crossing flow in microchannel and its application to gas analysis microchip  

Microsoft Academic Search

We developed a novel microchannel structure comprised of deep\\/shallow\\/deep tri-channels. Each end of the channel was split into three, and supplying and taking of fluids to\\/from the channels was possible. Aqueous solution tended to fill the shallow channel because of the capillary force. Thus, by introducing gas\\/liquid\\/gas from one end of the channel, stable laminar three-phase flow was formed throughout

H. Hachiya; M. Tokeshi; Y. Yoshida; T. Kitamori

2004-01-01

54

Analysis of finit in urine sample using thin layer chromatography.  

PubMed

Finit is a common insecticide generally used to control a variety of insects in homes. Routinely it is analysed by Gas Liquid Chromatography (GLC) and High Performance Liquid Chromatography (HPLC). An attempt has been made to develop a new method for analysis of finit in urine samples using Thin Layer Chromatography (TLC) technique which is inexpensive, accurate and non-destructive. Finit was extracted from urine using solvent extraction methods and then identified on the TLC plates. For detection on developed plates, palladium chloride, silver nitrate, iodine vapour and bromophenol blue were used which successfully increased the sensitivity without dispensing with the simplicity of the method. The method developed is simple, inexpensive, accurate and non-destructive that allows for sensitive and reproducible analysis of finit. PMID:23741873

Jaiswal, A K; Lal, Nand

2012-01-01

55

Application of gas-liquid chromatographic analysis of cellular fatty acids for species identification and typing of coagulase-negative staphylococci.  

PubMed Central

Gas-liquid chromatography (GLC) of bacterial cellular fatty acids was used to analyze 264 isolates of coagulase-negative staphylococci, of which 178 were Staphylococcus epidermidis. The presence and amounts of individual fatty acids were determined to generate fatty acid profiles for each of the seven coagulase-negative species tested. The fatty acid profiles were then analyzed by computerized correlation and cluster analysis to calculate mean correlation values between isolates belonging to the same or different species, as well as to establish cluster analysis dendrograms. These data ultimately allowed the clustering of individual samples into species-specific clusters. Species identification by the GLC clustering was highly consistent with species identification by biochemical assays; the results were similar in 92.4% of the cases. The GLC profile correlation analysis was further used to analyze multiple blood isolates from 60 patients in order to determine the usefulness of this methodology in establishing identity, as well as differences, between consecutive patient isolates. The correlation between those multiple S. epidermidis isolates determined to be identical by standard techniques (such as the antibiogram, biotype, and plasmid profile) was significantly (P less than 0.001) higher than that between random isolates of the same species. The correlation coefficient was greater than 97 for 40 (97.6%) of the 41 patients with multiple identical blood isolates, compared with less than 95 in all 19 (100.0%) patients with multiple nonidentical isolates. The successful use of the computerized GLC analysis in this study demonstrated its appropriate application for species identification and typing of coagulase-negative staphylococci. PMID:2007639

Kotilainen, P; Huovinen, P; Eerola, E

1991-01-01

56

Comparison of two gas-liquid chromatograph columns for the analysis of fatty acids in ruminant meat.  

PubMed

Two gas-liquid chromatograph capillary columns for the analysis of fatty acids (FA) in ruminant fat are compared. Those columns are the CP-Sil 88 of 100 m long with a highly polar stationary phase and the Omegawax 250 of 30 m long with a stationary phase of intermediate polarity. Fatty acid methyl ester (FAME) patterns of branched-chain, cis and trans octadecenoate isomers, as well as conjugated and non-conjugated 18:2 and 18:3 isomers are fairly different between columns, even though most of the FAME could be separated on either column. However, the CP-Sil 88 showed better resolution of 18:1 isomers than Omegawax 250. The analysis of 96 samples of ruminant meat fat in both chromatographic systems showed that averages obtained for total FA content and for most of the individual FA did not differ between columns. Moreover, regression analysis of Omegawax and CP-Sil 88 data is highly correlated. Quantitative differences between chromatographic systems were detected for samples containing more than 66 mg fatty acids per gram of muscle dry matter. PMID:19446820

Alves, Susana P; Bessa, Rui J B

2009-06-26

57

Modal Wavelets Analysis to Gas-Liquid Two Phase Flow PIV Images  

SciTech Connect

A modal wavelet transform, which overcomes the intrinsic data number limitation of power of two to conventional wavelet transform, has been applied to analysis of pseudo and real bubbly flow PIV images. The modal wavelet transform is compared with the discrete wavelet transform in order to select the best base function among Neumann, Dirichlet and Green function types base functions. Consequently, it is verified that Neumann type base function is the best because the correlation of Neumann type base function is the highest. From the result of wavelet analysis of the real bubbly flow PIV image, as the relative velocity is higher, the dominant eddy scale becomes smaller. The extraction modal wavelet level depends on the base function. (authors)

Masahiro Takei [Nihon University, 1866 Kameino, Fujisawa-Shi, Kanagawa 252-8510 (Japan); Hassan, Yassin A. [Texas A and M University, College Station, Texas 77843 (United States); Ortiz-Villafuerte, J. [National Institute for Nuclear Research, Carretera Mexico Toluca Km.36.5, 52045 Municipio de Ocoyoacac, Salazar. Edo. de Mexico, C.P.52046 Mexico (Mexico); Tomomasa Uemura [Kansai University, Suita-shi, Osaka 564 (Japan)

2006-07-01

58

Determination of partition coefficients of refrigerants by gas liquid chromatographic headspace analysis.  

PubMed

Gas-water partition coefficients, K(w), and gas-solvent partition coefficients, K(s), have been determined for chlorodifluoromethane and for 1,1,1,3,3,3-hexafluoropropane by headspace analysis, using a very simple experimental procedure. These partition coefficients then yield water-solvent partition coefficients, P(s). Where comparisons can be made there is excellent agreement with literature values for K(w) and P(s). The obtained values of K(s) and P(s) can be used to obtain physicochemical properties, or descriptors, for the refrigerants. Combination of these descriptors with previous equations we have developed enables partition coefficients to be obtained for a host of systems. PMID:23089519

Abraham, Michael H; Gil-Lostes, Javier; Corr, Stuart; Acree, William E

2012-11-23

59

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

60

Characterization by gas-liquid chromatography-mass spectrometry and proton-magnetic-resonance spectroscopy of pertrimethylsilyl methyl glycosides obtained in the methanolysis of glycoproteins and glycopeptides.  

PubMed Central

The quantitative analysis by gas chromatography of monosaccharides present in glycoproteins and glycopeptides using methanolysis, followed by re-N-acetylation and trimethylsilylation, gives rise to several peaks for each monosaccharide. The identity of these peaks for xylose, fucose, mannose, galactose, glucose, N-acetylglucosamine, N-acetylgalactosamine and N-acetylneuraminic acid was established for alpha- and beta-methyl pyranosides and furanosides by combined g.l.c.-mass spectrometry and proton-magnetic-resonance spectroscopy. These data provide for the unambiguous interpretation of the gas chromatograms obtained in the application of this g.l.c. method, and supply basic information for the further application of mass spectrometry in this field. PMID:1218089

Kamerling, J P; Gerwig, G J; Vliegenthart, J F; Clamp, J R

1975-01-01

61

Wavelet packet entropy feature extraction and characteristics analysis for gas\\/liquid two-phase flow regimes  

Microsoft Academic Search

Identification of flow regime is the basis for measuring flow parameters in two-phase flow accurately. Because of the complexity of phase interaction in gas-liquid two-phase flow, it is difficult to discern its flow regime objectively. The 208 measured data from electrical resistance tomography (ERT) are arranged into series based on section to derive the wavelet packet entropy and investigate the

Chun Fu; Feng Dong

2011-01-01

62

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

63

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

PubMed Central

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

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

1975-01-01

64

Gas-liquid chromatographic determination of total and free cholesterol in egg pastas  

Microsoft Academic Search

A gas—liquid chromatographic (GLC) method is described for the measurement of total and free cholesterol in egg pastas. This technique involves: extraction of lipids by reflux with isopropanol, fractional separation by adsorption liquid chromatography with elution gradient using petroleum ether-benzene and chromatographic determination.The present study has demonstrated that the GLC method is more specific than the colorimetric techniques. Gas-liquid chromatography

Enrique Agulló; Berta Susana Gelós

1996-01-01

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

Preparation of glycine-conjugated bile acids and their gas/liquid chromatographic analysis on an aluminum-clad flexible fused silica capillary column.  

PubMed

This paper describes a method for the direct gas/liquid chromatographic (GC) analysis of 46 glycine-conjugated bile acids, which differ from one another in the number, position and configuration of the hydroxyl groups at positions C-2, C-3, C-4, C-6, C-7 and/or C-12. Free bile acids were converted quantitatively on a micro scale to ethyl ester-trimethylsilyl (Et-TMS) and methyl ester-dimethylethylsilyl (Me-DMES) ether derivatives of the corresponding glycine conjugates. The Et-TMS and Me-DMES ethers of the glycine conjugates were chromatographed on an aluminum-clad flexible fused silica capillary column coated with a thin film (0.1 micron) of chemically bonded and cross-linked methylpolysiloxane. Relative retention time (RRT) and methylene unit (MU) values were determined for the 46 compounds and their GC behaviour was discussed. The derivatization procedure and the retention data would be useful for the direct GC identification of unknown glycine-conjugated bile acid mixtures extracted from biological samples. PMID:1600374

Iida, T; Tamaru, T; Chang, F C; Goto, J; Nambara, T

1992-01-01

67

Methodology development for the analysis of velocity particle image velocimetry images of turbulent, bubbly gas-liquid flows  

Microsoft Academic Search

Methods of analysing and interpreting two-dimensional velocity field data in order to understand the scales of turbulence of bubbly two-phase flow were developed. Reynolds decomposition and large eddy simulation (LES) decompositions (low-pass filtering), in conjunction with proper orthogonal decomposition (POD) energy spectra analysis, as well as adjusted convective decomposition (constant convection velocity is gas bubble velocity) were applied to analyse

X. Tu; C. Trägårdh

2002-01-01

68

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

Microsoft Academic Search

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

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

2001-01-01

69

Gas-liquid chromatographic screening method for six synthetic pyrethroid insecticides.  

PubMed

A method was developed for simultaneously determining 6 synthetic pyrethroid insecticides (fenpropanate, tetramethrin, permethrin, cypermethrin, fenvalerate, and deltamethrin) in apple, orange, grape, lemon, tomato, green pepper, and paprika, and sugar beet root and leaves. The pesticides were extracted with acetone and partitioned into methylene chloride. The extract was purified by column chromatography on active carbon-magnesia-diatomaceous earth and then on alumina. Analysis by gas-liquid chromatography with 63Ni electron capture detection was completed in 6 min on a 3% SE-30 liquid phase, using a short column. Recoveries from fortified samples ranged from 68 to 89% in the range of 0.3-1.0 ppm and from 67 to 83% in the range of 0.02-0.2 ppm. PMID:6885685

Bolygó, E; Zakar, F

1983-07-01

70

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

71

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

72

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

73

Chromatography.  

ERIC Educational Resources Information Center

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

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

74

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

75

Feature Extraction Method for Gas\\/Liquid Two-Phase Flow Based on Wavelets Transform  

Microsoft Academic Search

Gas\\/liquid two-phase flow system is a complex, nonlinear and dynamic system, therefore is difficult to measure. Basing on the application of electrical resistance tomography (ERT) in gas\\/liquid two-phase flow of vertical pipe, wavelets transform is used to analyses the measured data from ERT system. Furthermore, according to the multi-resolution analysis (MRA), the feature vector of multiple scales wavelet energy that

Meng-Meng Wu; Feng Dong; Guo-Hua Qi

2006-01-01

76

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

E-print Network

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

Tian, Weidong

77

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.

78

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

79

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.

WGBH Boston

2002-01-01

80

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.

81

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

82

Determination of microbial fatty acid profiles at femtomolar levels in human urine and the initial marine microfouling community by capillary gas chromatography-chemical ionization mass spectrometry with negative ion detection  

Microsoft Academic Search

Summary Room temperature esterification with the electron capturing pentafluorobenzyl bromide in glass capillaries, with analysis by capillary gas-liquid chromatography coupled with chemical ionization mass spectrometry and negative ion detection in the selected ion mode, allowed detection and identification of fatty acids from micro- bial biofilms at the femtomolar level. This sensitivity was achieved without loss of specificity of the mass

Goran Odham; Anders Tunlid; Gunilla Westerdahl; Lennart Larsson; James B. Guckert; David C. White

1985-01-01

83

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.

84

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.

2014-01-28

85

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

86

IMPROVED FAST GAS CHROMATOGRAPHY FOR FAME ANALYSIS OF BACTERIA  

Technology Transfer Automated Retrieval System (TEKTRAN)

Bacteria are frequently identified by fatty acid analysis. We previously reported on methods to speed up sample preparation and gas chromatography, resulting in greatly improved speed and throughput (Buyer, 2002). In this paper we demonstrate that further reductions in chromatographic retention time...

87

Analysis of steryl esters in cocoa butter by on-line liquid chromatography-gas chromatography.  

PubMed

On-line liquid chromatography-gas chromatography (LC-GC) has been applied to the analysis of steryl esters in cocoa butter. Separation of the steryl esters was achieved after on-line transfer to capillary GC. HPLC removes the large amount of triglycerides and pre-separates the components of interest, thus avoiding time-consuming sample preparation prior to GC analysis. The identities of the compounds were confirmed by GC-MS investigation of the collected HPLC fraction and by comparison of the mass spectra (chemical ionization using ammonia as ionization gas) to those of synthesized reference compounds. Using cholesteryl laurate as internal standard, steryl esters were quantified in commercial cocoa butter samples, the detection limit being 3 mg/kg and the quantification limit 10 mg/kg, respectively. Only slight differences in percentage distributions of steryl esters depending on the geographical origin of the material were observed. The patterns were shown to remain unchanged after deodorization. The method described might be a valuable tool for authenticity assessment of cocoa butter. PMID:11407581

Kamm, W; Dionisi, F; Fay, L B; Hischenhuber, C; Schmarr, H G; Engel, K H

2001-05-25

88

Lipid analysis by quantitative thin-layer chromatography  

Microsoft Academic Search

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

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

1965-01-01

89

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

90

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.

91

Measurement of real-time flow structures in gas–liquid and gas–liquid–solid flow systems using electrical capacitance tomography (ECT)  

Microsoft Academic Search

The real-time cross-sectional distributions of the gas holdups in gas–liquid and gas–liquid–solid systems are measured using electrical capacitance tomography. For the gas–liquid system, air as the gas phase and both Norpar 15 (paraffin) and Paratherm as the liquid phases are used. Polystyrene beads whose permittivity is similar to that of Paratherm are used as the solid phase in the gas–liquid–solid

W. Warsito; L.-S. Fan

2001-01-01

92

Principles of Micellar Electrokinetic Capillary Chromatography Applied in Pharmaceutical Analysis  

PubMed Central

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

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

2013-01-01

93

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

94

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

95

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

96

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

97

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

E-print Network

Recycling Size Exclusion Chromatography for the Analysis and Separation of Nanocrystalline Gold Ali University, MS-60 6100 Main Street, Houston, Texas 77025 Recycling size exclusion chromatography (RSEC defined sizes. This work aims to use size exclusion chromatography, or SEC, as a tool for evaluating

Richards-Kortum, Rebecca

98

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.

99

Journal of Chromatography A, 1159 (2007) 185189 Hair analysis for illicit drugs by using capillary zone  

E-print Network

Journal of Chromatography A, 1159 (2007) 185­189 Hair analysis for illicit drugs by using capillary to investigate retrospectively drug abuse histories. In this field, gas chromatography­mass spectrometry and high-performance liquid chromatography­mass spectrometry are currently used, often after pre- liminary screening

Miksik, Ivan

100

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

101

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

E-print Network

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

Linsen, Lars

102

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

103

Liquid chromatography: a tool for the analysis of metal species.  

PubMed

An overview is presented of classic and more recent applications of liquid chromatography for the analysis of metal species. The different approaches involving ion-exchange, ion-pair, and chelation separation mechanisms are discussed as well as the new philosophy of simply removing interferents before specific detections of metal ions (alkali and alakaline earths, rare earths, heavy and transition metals). New more selective materials enabling difficult separations and studies on multimodal or hyphenated techniques for metal speciation (e.g. arsenic and chromium) are considered. PMID:10457482

Sarzanini, C

1999-07-30

104

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

105

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

NASA Technical Reports Server (NTRS)

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

Lee, Jinho; Platt, Jonathan A.

1993-01-01

106

Gas-liquid chromatographic determination of organophosphorus insecticide residues in fruits and vegetables.  

PubMed

A method intended for regulatory purposes is described for the determination of organophosphorus insecticide residues in fruits and vegetables. Eighteen organophosphorus insecticides, azinphos-ethyl, chlorpyrifos, diazinon, dichlorvos, dimethoate, ethion, ethoate-methyl, fenitrothion, fenthion, formothion, malathion, methidathion, mevinphos, parathion, phosalone, phosphamidon, thiometon, and trichlorphon, and 7 metabolites, fenitrooxon, fenthion sulfoxide, fenthion sulfone, malaoxon, desethylphosphamidon, thiometon sulfoxide, and thiometon sulfone, were extracted from different crops with acetone and partitioned into hexane or ethyl acetate, according to their polarities. The hexane extract was cleaned up by eluting from a Florisil column with acetone-hexane (4+96). The ethyl acetate extract needs no cleanup. The concentrated extracts were analyzed by gas-liquid chromatography using thermionic detectors. Recoveries conducted at fortification levels ranging from 0.1 to 2 mg/kg were in most cases above 80%. The limit of sensitivity is less than 0.1 mg/kg. PMID:7430038

Ferreira, J R; Silva Fernandes, A M

1980-05-01

107

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

108

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

E-print Network

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

Barbuceanu, Nicolae

2001-01-01

109

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

110

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

111

Analysis of gentamicin by liquid chromatography with pulsed electrochemical detection.  

PubMed

The analysis of gentamicin by liquid chromatography using a column packed with poly(styrene-divinylbenzene) and pulsed electrochemical detection on a gold electrode is described. The mobile phase consists of an aqueous solution containing sodium sulfate, tetrahydrofuran, sodium 1-octanesulfonate and a phosphate buffer of pH 3.0. In contradistinction to methods previously published, this method not only allows a better separation of gentamicins C1, C1a, C2, C2a and C2b, but also the separation of several other, minor components, most of which were not identified. The effects of the different chromatographic parameters on the separation were also investigated. A number of commercial samples was analysed using this method, allowing sensitive detection of gentamicin without derivatization, and the results were compared with the results obtained with the European Pharmacopoeia method, prescribing pre-column derivatization. PMID:9919970

Adams, E; Roelants, W; De Paepe, R; Roets, E; Hoogmartens, J

1998-12-01

112

An improved method for analysis of biomass sugars and galacturonic acid by anion exchange chromatography  

Technology Transfer Automated Retrieval System (TEKTRAN)

While the most accurate method for analysis of sugars in biomass is based on gas chromatography of trimethylsilane or alditol acetate derivitives of sugars, the derivation method is time consuming and laborious. In comparison, sample preparation for sugar analysis using liquid chromatography is a si...

113

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

114

Numerical simulation of dispersed gas-liquid flows  

Microsoft Academic Search

This paper reviews the available information on numerical simulation of dispersed gas-liquid flows. Emphasis is on informing\\u000a the reader about various aspects of constructing simulation models rather than giving an exhaustive literature review. The\\u000a information is organised in a way so as to provide answers to the following questions: how to formulate model equations? how\\u000a to select suitable algorithms and

V V Ranade

1992-01-01

115

Potential Structure Formation in the Gas-Liquid Interfacial Plasmas  

NASA Astrophysics Data System (ADS)

Specific kinds of plasmas composed of ionic liquids and gas phase discharge plasmas are created. These novel gas-liquid interfacial plasmas could contribute to the effective creation and modification of nano-bio materials, where the control of ion behavior in both the gas and liquid phases is desired. In this study, the plasma source containing the ionic liquids is developed for clarifying the effects of the ionic liquids on the plasma generation and the potential structure formed in the gas-liquid interfacial region is investigated for controlling the ion motion A direct current (DC) or a pulsed DC discharge plasma is generated just above the ionic liquid by applying the DC or the pulsed DC voltage to an electrode immersed in the ionic liquid against a grounded electrode set in the gas phase region. The precise potential structure between these electrodes through the gas-liquid interfacial region is clarified, and the dynamics of the plasma ions is found to be controlled using the sheath electric field in the interfacial region. The control of the plasma ion irradiation flux and energy to the ionic liquid leads to the creation of various kinds of nanoparticles.

Kaneko, Toshiro; Harada, Takashi; Chen, Qiang; Hatakeyama, Rikizo

2009-11-01

116

Sample preparation and reversed phase-high performance liquid chromatography analysis of food-derived peptides  

Microsoft Academic Search

Reversed phase-high performance liquid chromatography (RP-HPLC) is an indispensable technique in food peptide research. This paper briefly reviews the methods for isolation and RP-HPLC analysis of food-derived peptides. A critical aspect is the sample preparation and clean-up. For this, selective precipitation, ultrafiltration, size exclusion chromatography, ion-exchange chromatography and solid phase extraction (SPE) are used. SPE with non-polar or ion-exchange cartridges,

T. Herraiz

1997-01-01

117

Gas-Liquid flow characterization in bubble columns with various gas-liquid using electrical resistance tomography  

Microsoft Academic Search

Electrical resistance tomography (ERT) is an advanced and new detecting technique that can measure and monitor the parameters of two-phase flow on line, such as gas-liquid bubble column. It is fit for the industrial process where the conductible medium serves as the disperse phase to present the key bubble flow characteristics in multi-phase medium. Radial variation of the gas holdup

Haibo Jin; Han Yuhuan; Yang Suohe

2009-01-01

118

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

SciTech Connect

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

X. Wang; X. Sun; H. Zhao

2011-09-01

119

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

120

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.

121

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

122

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

123

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

124

GAS/LIQUID MEMBRANES FOR NATURAL GAS UPGRADING  

SciTech Connect

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

Howard S. Meyer

2003-04-01

125

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

126

[High-performance liquid-liquid chromatography in beverage analysis].  

PubMed

Liquid liquid chromatography was performed with columns packed with stationary phases chemically bonded to silica microparticules. These columns show a high efficiency and are used very easily. Flavouring compounds like aromatic aldehydes which have a low volatility were analyzed in brandy using a polar phase alkylnitrile. Sapid substances like amarogentin in Gentiana lutea or glyryrrhizin in Glycyrrhiza glabra were determined by reversed phase chromatography. Finally ionizable substances like synthetic dyes can be analyzed by paired ion chromatography witha non polar stationary phase. PMID:754597

Bricout, J; Koziet, Y; de Carpentrie, B

1978-01-01

127

Determining phase diagrams of gas-liquid systems using a microfluidic PVT.  

PubMed

A novel microfluidic device designed for analyzing phase diagrams of gas-liquid systems (PVT or pressure-volume-temperature measurements) is described. The method mimics the phase transition of a reservoir fluid as it travels through the wellbore from the formation to the surface. The device consists of a long serpentine microchannel etched in a silicon substrate. The local pressure inside the channel is measured using membrane-based optical pressure sensors positioned along the channel. Geometrical restrictions are placed along the microchannel in order to nucleate bubbles when nucleation conditions are met, thus preventing the development of a supersaturation state in the channel. We point out that a local equilibrium state between gas and liquid phases is achieved, which implies that equilibrium properties can be directly measured on the chip. We analyze different mixtures of hydrocarbon systems and, consistently with the preceding analysis, obtain excellent agreement between our technique and conventional measurements. From a practical viewpoint (important for the relevance of the technology), we observe that the measurement time of thermodynamic properties of gas-liquid systems is reduced from hours to minutes with the present device without compromising the measurement accuracy. PMID:22930353

Mostowfi, Farshid; Molla, Shahnawaz; Tabeling, Patrick

2012-11-01

128

Vibration-Induced Gas-Liquid Interface Breakup  

NASA Astrophysics Data System (ADS)

Gas-liquid interfaces can be forced to break up when subjected to vibrations within critical ranges of frequency and amplitude. This breakup mechanism was examined experimentally using deep layers of silicone oils over a range of viscosity and sinusoidal, primarily axial vibration conditions that can produce dramatic disturbances at the gas-liquid free surface. Although small-amplitude vibrations produce standing Faraday waves, 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 transport below the interface. Experiments used several different silicone oils over a range of pressures and vibration conditions. Computational simulations exhibiting similar behavior will be included in the presentation. Applications include liquid fuel rockets, inertial sensing devices, moving vehicles, mixing processes, and acoustic excitation. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

O'Hern, Timothy; Torczynski, John; Romero, Ed; Shelden, Bion

2010-11-01

129

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...

130

QUANTITATIVE ANALYSIS OF 68 POLAR COMPOUNDS FROM TEN CHEMICAL CLASSES BY DIRECT AQUEOUS INJECTION GAS CHROMATOGRAPHY  

EPA Science Inventory

Porous polymer packings have been used successfully in many applications of direct aqueous injection gas chromatography. The authors have expanded the use of aqueous injection to the quantitative analysis of 68 alcohols, acetates, ketones, ethers, sulfides, aldehydes, diols, dion...

131

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

EPA Science Inventory

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

132

[Column chromatography purification and analysis of biodiesel by transesterification].  

PubMed

In the present paper, crude biodiesel prepared with sorbifolia oil as raw material by transesterification was purified by column chromatography, then the composition of biodiesel was analyzed by gas chromatography, FTIR, GC-MS and 1H NMR. Column chromatography can separate the crude biodiesel into two fractions: petroleum ether eluted fraction (A1) and methanol eluted fraction (A2). Petroleum ether eluted fraction was mainly biodiesel fraction, which was produced from sorbifolia oil by transesterification, including methyl linoleate, methyl cis-9-octadecenoate and so on; methanol eluted fraction was mainly glycerol fraction, which came from the side reaction of transesterification. The results show that the purity of refined biodiesel increased from 77.51% to 93.872, and the product recovery rate reached up to 91.04% after the purification by column chromatography. The results obtained by FTIR and 1H NMR further showed that the column chromatography can effectively improve the purity of biodiesel. This paper provides a basis for industrialization of purification of biodiesel. PMID:22512199

Liu, Yang; Yi, Huai-feng; Chen, Yu; Wu, Yu-long; Yang, Ming-de; Chen, Zeng; Tong, Jun-mao

2012-02-01

133

Comparison of liquid chromatography-microchip/mass spectrometry to conventional liquid chromatography-mass spectrometry for the analysis of steroids.  

PubMed

The feasibility of a microfluidic-based liquid chromatography-electrospray ionization/mass spectrometric system (HPLC-Chip/ESI/MS) was studied and compared to a conventional narrow-bore liquid chromatography-electrospray ionization/mass spectrometric (LC-ESI/MS) system for the analysis of steroids. The limits of detection (LODs) for oxime derivatized steroids, expressed as concentrations, were slightly higher with the HPLC-Chip/MS system (50-300 pM) using an injection volume of 0.5 ?L than with the conventional LC-ESI/MS (10-150 pM) using an injection volume of 40 ?L. However, when the LODs are expressed as injected amounts, the sensitivity of the HPLC-Chip/MS system was about 50 times higher than with the conventional LC-ESI/MS system. The results indicate that the use of HPLC-Chip/MS system is clearly advantageous only in the analysis of low-volume samples. Both methods showed good linearity and good quantitative and chromatographic repeatability. In addition to the instrument comparisons with oxime derivatized steroids, the feasibility of the HPLC-Chip/MS system in the analysis of non-derivatized and oxime derivatized steroids was compared. The HPLC-Chip/MS method developed for non-derivatized steroids was also applied to the quantitative analysis of 15 mouse plasma samples. PMID:22405309

Ahonen, Linda; Keski-Rahkonen, Pekka; Saarelainen, Taija; Paviala, Jenni; Ketola, Raimo A; Auriola, Seppo; Poutanen, Matti; Kostianen, Risto

2012-04-01

134

GAS/LIQUID MEMBRANES FOR NATURAL GAS UPGRADING  

SciTech Connect

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

Howard S. Meyer

2003-10-01

135

GAS/LIQUID MEMBRANES FOR NATURAL GAS UPGRADING  

SciTech Connect

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

Howard S. Meyer

2003-07-01

136

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...

137

Analysis of enrichment factor of uranium enrichment by Redox chromatography  

Microsoft Academic Search

Experiments and computer simulation show that the uranium enrichment factor in redox chromatography is determined substantially be electron exchange, isotope adsorption-desorption, and oxidation state adsorption-desorption equilibria. Computer simulation utilizing the theoretical model closely predicts the difference between the value of an enrichment factor derived from the solution equilibrium and that observed in the chromatographic isotope separation, which is attributable to

T. Muyake; K. Takeda; H. Onitsuka; T. Watanabe

1986-01-01

138

Mass Accommodation and Chemical Reaction at Gas-Liquid Interfaces  

NASA Astrophysics Data System (ADS)

The uptake of trace gases by liquid surfaces is an important process that initiates the heterogeneous chemistry of liquid aerosol particles and cloud droplets. We have recently reviewed the available experimental data for liquid aqueous and aqueous/organic surfaces (1). The review highlights some inconsistencies among experimental results and between experimental results and molecular dynamics simulations. Some of these inconsistencies will be evaluated and discussed in terms of the physics of liquid interfaces, the limitations of various experimental techniques and the disparate scales of laboratory experiments and current molecular simulations (1, 2). 1. Davidovits, P., Kolb, C. E., Williams, L. R., Jayne, J. T., Worsnop, D. R., 2006, Mass Accommodation and Chemical Reactions at Gas Liquid Interfaces, Chem. Rev. 106, 1323-1354. 2. Garrett, B. C., Schenter, G. K., Morita, A., 2006, Molecular Simulations of Molecules across the Liquid/Vapor Interface of Water, Chem. Rev. 106, 1355-1374.

Kolb, C. E.; Williams, L. R.; Jayne, J. T.; Worsnop, D. R.; Davidovits, P.

2006-12-01

139

CARBON DIOXIDE SEPARATION BY PHASE ENHANCED GAS-LIQUID ABSORPTION  

SciTech Connect

A new process called phase enhanced gas-liquid absorption has been developed in its early stage. It was found that adding another phase into the absorption system of gas/aqueous phase could enhance the absorption rate. A system with three phases was studied. In the system, gas phase was carbon dioxide. Two liquid phases were used. One was organic phase. Another was aqueous phase. By addition of organic phase into the absorption system of CO{sub 2}-aqueous phase, the absorption rate of CO{sub 2} was increased significantly. CO{sub 2} finally accumulated into aqueous phase. The experimental results proved that (1) Absorption rate of carbon dioxide was enhanced by adding organic phase into gas aqueous phase system; (2) Organic phase played the role of transportation of gas solute (CO{sub 2}). Carbon dioxide finally accumulated into aqueous phase.

Liang Hu

2004-09-30

140

CARBON DIOXIDE SEPARATION BY PHASE ENHANCED GAS-LIQUID ABSORPTION  

SciTech Connect

A new process called phase enhanced gas-liquid absorption has been developed in its early stage. It was found that adding another phase into the absorption system of gas/aqueous phase could enhance the absorption rate. A system with three phases was studied. In the system, gas phase was carbon dioxide. Two liquid phases were used. One was organic phase. Another was aqueous phase. By addition of organic phase into the absorption system of CO{sub 2}-aqueous phase, the absorption rate of CO{sub 2} was increased significantly. CO{sub 2} finally accumulated into aqueous phase. The experimental results proved that (1) Absorption rate of carbon dioxide was enhanced by adding organic phase into gas aqueous phase system; (2) Organic phase played the role of transportation of gas solute (CO{sub 2}). Carbon dioxide finally accumulated into aqueous phase.

Liang Hu; Adeyinka A. Adeyiga

2004-05-01

141

Modeling gas-liquid head performance of electrical submersible pumps  

NASA Astrophysics Data System (ADS)

The objectives of this study are to develop a simple and accurate theoretical model and to implement the model into a computational tool to predict Electrical Submersible Pumps (ESP) head performance under two-phase flow conditions. A new two-phase model including a set of one-dimensional mass and momentum balance equations was developed. The derived gas-liquid momentum equations along pump channels has improved Sachdeva (1992, 1994)'s model in petroleum industry and generalized Minemura (1998)'s model in nuclear industry. The resulting pressure ODE for frictionless incompressible single-phase flow is consistent with the pump Euler equation. In the two-phase momentum equations, new models for wall frictional losses for each phase, through using gas-liquid stratified assumption and existing correlations for impeller rotating effect, channel curvature effect, and channel cross section effect, have been proposed. New equations for radius of curvature along ESP channels, used in the curvature effect calculation, have been derived. A new shock loss model incorporating rotational speeds has been developed. A new correlation for drag coefficient and interfacial characteristic length effects has been obtained through fitting the model results with experimental data. An algorithm to solve the model equations has been developed and implemented. The model predicts pressure and void fraction distributions along impellers and diffusers and can also be used to predict the pump head performance curve under different fluid properties, pump intake conditions, and rotational speeds. The new two-phase model is validated with air-water experimental data. Results show the model provides a very good prediction for pump head performance under different gas flow rates, liquid flow rates, and different intake pressures. The new model is capable of predicting surging and gas lock conditions.

Sun, Datong

142

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

143

Simplified and improved methylation analysis of saccharides, using a modified procedure and thin-layer chromatography  

Microsoft Academic Search

Methylation analysis used in determining the positions of glycosidic linkages in oligo- and poly-saccharides has been greatly simplified by eliminating two of the usual reactions, reduction and acetylation of the methylated monosaccharide residues. The saccharides are methylated by the Hakomori procedure, followed by acid hydrolysis and analysis by thin-layer chromatography (TLC). The procedure is illustrated by analysis of four known

Rupendra Mukerjea; Doman Kim; John F. Robyt

1996-01-01

144

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

E-print Network

41 Designing nanostructured heterogeneous catalysts to exploit pulsing in gas-liquid packed bed nanostructured catalysts for gas-liquid reactions, which have a system of macro pores designed to take advantage encourage similar studies to look for links between nanostructured materials for separation processes

McCready, Mark J.

145

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

E-print Network

Summary: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Proved Reserves 2009 November 2010 U.S. Energy Information Administration Office of Oil, Gas, and Coal Supply Statistics U.S. Department or other Federal agencies. #12;#12;1 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Proved Reserves

Boyer, Elizabeth W.

146

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

PubMed

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

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

2015-02-01

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.

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

148

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

149

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

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

Comprehensive supercritical fluid chromatography x reversed phase liquid chromatography for the analysis of the fatty acids in fish oil.  

PubMed

The separation of the phenacyl esters of the fatty acids originating from a fish oil extract by means of a comprehensive analysis using silver-ion (SI) supercritical fluid chromatography (SFC) and reversed phase liquid chromatography (RP-LC) in the first and second dimensions, respectively, is described. The combination ensured a high orthogonality and peak capacity, particularly when compared to the comprehensive RP-LC x 2RP-LC separation achieved by using a configuration with two columns in parallel in the second dimension. The construction of the SI-SFC x RP-LC interface consists of two two-position/ten-port switching valves, of which one is equipped with two loops packed with octadecyl silica (ODS) particles. Compared to the SFC x RP-LC configuration described in an earlier publication, the peak capacity in the second dimension was increased. Water was not only added as make-up fluid to the SFC effluent to ensure analyte focusing, but also as rinsing medium of the loops prior to the transfer of the fractions to the second dimension. In the SFC dimension, high efficiency and loadability were obtained by coupling two wide-bore columns (4.6 mm ID) in series. Evaporative light scattering (ELSD) and ultraviolet (UV) detection with standard and high-pressure flow cells were evaluated in terms of data acquisition speed and suppression of signal interferences originating from the supercritical carbon dioxide (CO(2)) expansion. PMID:19286185

François, Isabelle; Sandra, Pat

2009-05-01

152

Analysis of dimerized fatty acids by TLC\\/FID  

Microsoft Academic Search

A rapid method is described for the analysis of the monomer, dimer and trimer components of polymerized fatty acids by thin\\u000a layer chromatography (TLC) with flame ionization detection (FID) on the Iatroscan. The short- and long-term precisions of\\u000a the method are discussed, as is the correlation of TLC\\/FID data with the gas-liquid Chromatographic (GLC) data for dimerized\\u000a fatty acids. The

David W. Fritz; Francis Amore; Ken Rashmawi

1988-01-01

153

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

E-print Network

Proteomic Analysis of SARS Associated Coronavirus Using Two-Dimensional Liquid Chromatography Mass 25, 2003 The proteomes of the severe acute respiratory syndrome-associated coronavirus (SARS in the analysis of other viruses. Keywords: coronavirus · proteome · mass spectrometry · glycosylation

Tian, Weidong

154

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

ERIC Educational Resources Information Center

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

Hess, Amber Victoria Irish

2007-01-01

155

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

SciTech Connect

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

Xia Wang; Xiaodong Sun; Benjamin Doup; Haihua Zhao

2012-12-01

156

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

157

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

158

Liquid chromatography MALDI MS/MS for membrane proteome analysis.  

PubMed

Liquid chromatography (LC) can be combined with matrix-assisted laser-desorption ionization (MALDI) mass-spectrometry (MS) by using automated off-line fraction collection of eluates onto a MALDI plate. Commercial tandem MS systems are available for generating product ion spectra of MALDI-produced peptide ions. The MALDI MS/MS spectra can be searched against a proteome database for protein identification. In this chapter, a protocol of sequential solubilization and digestion of membrane proteins involving methanol- and SDS-assisted trypsin digestion and microwave-assisted acid hydrolysis is presented. The process of LC eluate deposition onto a MALDI plate along with practical considerations for achieving optimal performance of eluate deposition is described. Issues related to MALDI MS and MS/MS spectral acquisition are discussed. Database searching and manual inspection of MS/MS spectra of singly charged MALDI-produced peptide ions for positive protein identification are also addressed. PMID:19153701

Wang, Nan; Young, J Bryce; Li, Liang

2009-01-01

159

Gas-Liquid flow characterization in bubble columns with various gas-liquid using electrical resistance tomography  

NASA Astrophysics Data System (ADS)

Electrical resistance tomography (ERT) is an advanced and new detecting technique that can measure and monitor the parameters of two-phase flow on line, such as gas-liquid bubble column. It is fit for the industrial process where the conductible medium serves as the disperse phase to present the key bubble flow characteristics in multi-phase medium. Radial variation of the gas holdup and mean holdups are investigated in a 0.160 m i. d. bubble column using ERT with two axial locations (Plane 1 and Plane 2). In all the experiments, air was used as the gas phase, tap water as liquid phase, and a series of experiments were done by adding KCl, ethanol, oil sodium, and glycerol to change liquid conductivity, liquid surface tension and viscosity. The superficial gas velocity was varied from 0.02 to 0.2 m/s. The effect of conductivity, surface tension, viscosity on the mean holdups and radial gas holdup distribution is discussed. The results showed that the gas holdup decrease with the increase of surface tension and increase with the increase of viscosity. Meanwhile, the settings of initial liquid conductivity slightly influence the gas holdup values, and the experimental data increases with the increase of the initial setting values in the same conditions.

Jin, Haibo; Yuhuan, Han; Suohe, Yang

2009-02-01

160

Reliable separation of cis and trans fatty acids by gas liquid chromatography on glass capillary columns  

Microsoft Academic Search

Because of the recent progress in lipid research, the availability of an excellent separation method for fatty acid methyl esters has become more and more important. A speical need exists for a good separation of cis and trans isomers, and of isomers with different positions of double-bonds. This goal was achieved by applying a 50 m glass-capillary column with an

H. Jaeger; H.-U. Klör; G. Blos; H. Ditschuneit

1975-01-01

161

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

162

Improved resolution of natural diacylglycerols by gas-liquid chromatography on polar siloxanes.  

PubMed

A new cyanoalkylphenylsiloxane (SILAR 5CP) liquid phase is shown to possess sufficient polarity to permit improved GC separations of natural diacylglycerols based on unsaturation and positional placement of fatty acids as well as on molecular weight, which was previously possible only on ethylene glycol succinate polyesters. Unlike the polyesters, the polar siloxane polymer has moderate thermal stability and provides GC columns which can be used for several months without replacing the packing. The GC analyses were made with conventional columns containing 3% SILAR 5CP on Gas Chrom Q at 270 degrees C isothermally. The diacylglycerols were chromatographed as the TMS ethers. Excellent seperations were obtained for the 1,2(2,3)- and 1,3-diacyglycerols derived from corn, linseed, peanut and cod liver oils and for the 1,2-diacyl-sn-glycerols from hepatic glycerophospholipids. PMID:1150850

Myher, J J; Kuksis, A

1975-03-01

163

Use of gas liquid chromatography for monitoring the fatty acid composition of canadian rapeseed  

Microsoft Academic Search

Since 1972, Canadian rapeseed has been changing from high erucic acid types to low erucic acid types. In 1970, the Canadian\\u000a Grain Commission instituted a program to monitor the fatty acid composition of rapeseed at the farm level, in railway carlot\\u000a shipments and in export cargo shipments. Initially, in order to process up to 20,000 samples per year, a combined

J. K. Daun; P. B. Mazur; C. J. Marek

1983-01-01

164

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

E-print Network

and Shewan, 1968; Herbert et al. , 1971; Miller et al. , 1973 a, b, c; Shewan, 1974). The S-containing compounds are thought to be the most important as spoilage odor components. Pseudomonas fl, P * do g 1, P do g t'd and Pseudomonas utrefaciens have all... materials including: unflavored textured soy protein (Ames and MacLeod, 1984), canned and freeze dried carrots 12 (Heatherbell et al. , 1971; Heatherbell and Wrolstad, 1971) turkey sausage (Barbut et al. , 1985), cheeses (Liebich et al. , 1970; Lin...

Scorah, Craig Darrell Allen

2012-06-07

165

Journal of Chromatography B, 857 (2007) 6775 Stereoselective analysis of bupropion and hydroxybupropion  

E-print Network

Journal of Chromatography B, 857 (2007) 67­75 Stereoselective analysis of bupropion)- and (S)- bupropion and its major metabolite (R,R)- and (S,S)-hydroxybupropion in human plasma and urine.5 to 1000 ng/ml in each bupropion and hydroxybupropion enantiomer, respectively. The assay was linear

Steinbach, Joe Henry

166

Ink analysis from typed script of electronic typewriters by high performance thin layer chromatography  

Microsoft Academic Search

The analysis of ink from the typed script of seven electronic typewriters is carried out by high performance thin layer chromatography. The resultant Rf values and in situ visible spectrum of each resolved band of all the chromatograms indicate that the same chemical composition is being used in six typewriter ribbon inks, but that the seventh one is completely different.

K. M. Varshney; Tonni Jettappa; V. K. Mehrotra; T. R. Baggi

1995-01-01

167

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

EPA Science Inventory

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

168

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 ...

169

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

170

Analysis of organic\\/inorganic analytes in environmental samples by packed capillary chromatography  

Microsoft Academic Search

Recent progress in the development of techniques for packing of high efficiency capillary columns has enabled the concept of unified chromatography to be realised. Packed capillary columns offer the advantages of both packed column (high loading capacity, wide range of stationary phases) and capillary column (speed of analysis, high resolution) techniques to produce a versatile and efficient analytical procedure. For

M. D. Burford; M. M. Robson; S. C. Mitchell

1995-01-01

171

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

Microsoft Academic Search

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

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

2007-01-01

172

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

ERIC Educational Resources Information Center

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

Clark, Daniel D.

2007-01-01

173

Gas Chromatography  

NSDL National Science Digital Library

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

174

Analysis of Pendimethalin Residues in Fruit, Nuts, Vegetables, Grass, and Mint by Gas Chromatography  

Microsoft Academic Search

Pendimethalin (N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine), in the formulation of Prowl (a commercial herbicide), was applied to various crops. Analysis of pendimethalin and its metabolite (4(1-ethylpropyl)amino-2-methyl-3,5-dinitrobenzyl alcohol) was accomplished by utilizing liquid- liquid partitioning, gel permeation chromatography (GPC) for nuts and mint, solid-phase extraction (SPE) cleanup, and gas chromatography (GC) with a nitrogen-phosphorus detector (NPD). Method validation recoveries for fruits, nuts, vegetables, grass, and

J. Engebretson; G. Hall; M. Hengel; T. Shibamoto

2001-01-01

175

Effect of surfactant additives on co-current gas–liquid downflow  

Microsoft Academic Search

The influence of a surfactant additive on the interfacial structure and on the transition from the smooth to the wavy stratified flow regime in inclined pipes is investigated for various gas–liquid flow rates. The effect of a surfactant on the gas–liquid stratified downflow patterns is studied using a dilute aqueous solution of a non-ionic surfactant (Tween®80), which is found to

J. S. Lioumbas; A. A. Mouza; S. V. Paras

2006-01-01

176

Determination of the pressure at the gas-liquid interface using acoustic speed measurements  

E-print Network

DETERMINATION OF THE PRESSURE AT THE GAS-LIQUID INTERFACE USING ACOUSTIC SPEED MEASUREMENTS A Thesis by DAG GUSTAV HEGGELUND Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE August 1988 Major Subject: Petroleum Engineering DETERMINATION OF THE PRESSURE AT THE GAS-LIQUID INTERFACE USING ACOUSTIC SPEED MEASUREMENTS A Thesis by DAG GUSTAV HEGGELUND Approved as to style and content by: W. nnin ( air...

Heggelund, Dag Gustav

1988-01-01

177

Shotgun proteome analysis utilising mixed mode (reversed phase-anion exchange chromatography) in conjunction with reversed phase liquid chromatography mass spectrometry analysis.  

PubMed

The 2-D peptide separations employing mixed mode reversed phase anion exchange (MM (RP-AX)) HPLC in the first dimension in conjunction with RP chromatography in the second dimension were developed and utilised for shotgun proteome analysis. Compared with strong cation exchange (SCX) typically employed for shotgun proteomic analysis, peptide separations using MM (RP-AX) revealed improved separation efficiency and increased peptide distribution across the elution gradient. In addition, improved sample handling, with no significant reduction in the orthogonality of the peptide separations was observed. The shotgun proteomic analysis of a mammalian nuclear cell lysate revealed additional proteome coverage (2818 versus 1125 unique peptides and 602 versus 238 proteins) using the MM (RP-AX) compared with the traditional SCX hyphenated to RP-LC-MS/MS. The MM analysis resulted in approximately 90% of the unique peptides identified present in only one fraction, with a heterogeneous peptide distribution across all fractions. No clustering of the predominant peptide charge states was observed during the gradient elution. The application of MM (RP-AX) for 2-D LC proteomic studies was also extended in the analysis of iTRAQ-labelled HeLa and cyanobacterial proteomes using nano-flow chromatography interfaced to the MS/MS. We demonstrate MM (RP-AX) HPLC as an alternative approach for shotgun proteomic studies that offers significant advantages over traditional SCX peptide separations. PMID:20662100

Phillips, Helen L; Williamson, James C; van Elburg, Karin A; Snijders, Ambrosius P L; Wright, Phillip C; Dickman, Mark J

2010-08-01

178

Qualitative analysis of mycotoxins using micellar electrokinetic capillary chromatography  

SciTech Connect

Naturally occurring mycotoxins are separated using micellar electrokinetic capillary chromatography. Trends in the retention of these toxins, resulting from changes in mobile-phase composition and pH, are reported and presented as a means of alleviating coelution problems. Two sets of mobile-phase conditions are determined that provide unique separation selectivity. The facile manner by which mobile-phase conditions can be altered, without changes in instrumental configuration, allowed the acquisition of two distinctive, fully resolved chromatograms of 10 mycotoxins in a period of approximately 45 min. By adjusting retention times, using indigenous or added components in mycotoxin samples as normalization standards, it is possible to obtain coefficients of variation in retention time that average less than 1%. The qualitative capabilities of this methodology are evaluated by separating randomly generated mycotoxin-interferent mixtures. In this study, the utilization of normalized retention times applied to separations obtained with two sets of mobile-phase conditions permitted the identification of all the mycotoxins in five unknown samples without any misidentifications. 24 refs., 3 figs., 2 tabs.

Holland, R.D.; Sepaniak, M.J. (Univ. of Tennessee, Knoxville (United States))

1993-05-01

179

Phytochemical analysis of ethanolic extract of Dichrostachys Cinerea W and Arn leaves by a thin layer chromatography, high performance thin layer chromatography and column chromatography  

PubMed Central

Background: The leaves of Dichrostachys cinerea are used as laxative, diuretic, painkiller. It is also used in the treatment of gonorrhoea, boils, oedema, gout, veneral diseases and nasopharyngeal affections, etc. Materials and Methods: The Phytochemical investigation of ethanolic extract of D. cinerea leaves were performed by standard chemical tests, thin layer chromatography (TLC) by using various solvent systems, and by high performance liquid chromatography (HPTLC). Two compounds were isolated by column chromatography and one of the compounds was identified by various spectral studies. Result: Preliminary phytochemical screening of ethanolic extract of D. cinerea leaves showed the presence of Carbohydrates, proteins, Glycosides, Saponins, Tannins, Aminoacids and Terpenoids. The TLC and HPTLC fingerprint of ethanolic extract were studied and various fractions were isolated by column chromatography and one of the fraction contain ?-amyrin glucoside which was confirmed by Infra Red[IR] Spectroscopy, 1H-Nuclear Magnetic Resonance (NMR), C-13 NMR and Mass spectroscopic (MS) studies. PMID:24991072

Vijayalakshmi, M.; Periyanayagam, K.; Kavitha, K.; Akilandeshwari, K.

2013-01-01

180

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

181

Analysis of glycylsarcosine transport by lobster intestine using gas chromatography.  

PubMed

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

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

2014-09-27

182

High-performance liquid chromatography with fluorescence detection for aqueous analysis of nanogram-level Nnitrosodimethylamine  

Microsoft Academic Search

High-performance liquid chromatography (HPLC) and fluorescence derivatization were applied for a nanogram-level N-nitrosodimethylamine (NDMA) analysis of water samples. For the analysis of N-nitrosodimethylamine, samples were first denitrosated by a mixed solution of hydrobromic acid and acetic acid to produce dimethylamine, which was derivatized with dansyl chloride for HPLC fluorescence detection. Fluorescence detection was optimized with excitation and emission wavelengths of

Woosuk Cha; Peter Fox; Brijesh Nalinakumari

2006-01-01

183

Estimation of ?-cyfluthrin and imidacloprid in okra fruits and soil by chromatography techniques  

Microsoft Academic Search

Dissipation of ?-cyfluthrin and imidacloprid in okra was studied following three applications of a combination formulation of Solomon 300 OD (?-cyfluthrin 9 % + imidacloprid 21 %) @ 60 and 120 g a.i. ha at 7 days interval. Residues of ?-cyfluthrin and imidacloprid in okra were estimated by gas liquid chromatography (GLC) and high performance liquid chromatography (HPLC), respectively. Residues

S. K. Sahoo; G. S. Chahil; Kousik Mandal; R. S. Battu; Balwinder Singh

2012-01-01

184

SUPERCRITICAL FLUID CHROMATOGRAPHY FOR HIGH MOLECULAR WEIGHT ORGANIC ANALYSIS  

EPA Science Inventory

The report describes a preliminary application of supercritical fluid mass spectrometry (MS) techniques to the analysis of a middle distillate fuel, an emission particulate extract, and the emission particulates themselves. These techniques include capillary column supercritical ...

185

High-throughput simultaneous analysis of pesticides by supercritical fluid chromatography/tandem mass spectrometry.  

PubMed

Combination techniques such as gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS) are commonly used for pesticide residue analysis, but there is no reported method for the simultaneous analysis of multiple pesticides in a sample using a single instrument. Supercritical fluid chromatography (SFC) offers high resolution at high flow rates and various separation modes and hence may aid the rapid simultaneous analysis of pesticide. We developed an SFC/MS/MS method and analyzed 17 pesticides with a wide range of polarities (logP(ow)=-4.6 to 7.05) and molecular weights (112.1-888.6) within 11min using a polar-embedded reversed-phase column. To the best of our knowledge, there is no previous report on the SFC analysis of a wide variety of compounds, including highly hydrophilic ones. By SFC, diquat dibromide (logP(ow)=-4.6), together with cypermethrin (logP(ow)=6.6) and tralomethrin (logP(ow)=5.05), could be detected in the presence of various other pesticides using a single mobile phase. SFC/MS allows for the rapid and simultaneous analysis of low concentrations (ng/L levels) of pesticides that typically need to be analyzed by GC/MS and LC/MS separately. PMID:23102524

Ishibashi, Megumi; Ando, Takashi; Sakai, Miho; Matsubara, Atsuki; Uchikata, Takato; Fukusaki, Eiichiro; Bamba, Takeshi

2012-11-30

186

Analysis of anions in geological brines using ion chromatography  

SciTech Connect

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

Merrill, R.M.

1985-03-01

187

Qualitative Analysis of Herbs by Gas Chromatography\\/Mass Spectrometry (GC\\/MS). An Undergraduate Instrumental Analysis Laboratory Exercise  

Microsoft Academic Search

A laboratory exercise to be used in an undergraduate instrumental methods course is presented for the qualitative analysis of interesting real-world herbal extracts. The objective of this experiment is to familiarize students with a modern experimental method gas chromatography\\/mass spectrometry (GC\\/MS).

JEREMY TIPTON; TICIA BARNICKI; EUGENE T. SMITH

1998-01-01

188

Concentration effect in hyaluronan analysis by size exclusion chromatography  

Microsoft Academic Search

The concentration effect in size-exclusion chromatographic analysis of hyaluronans of various relative molecular masses (RMM) has been studied. A critical concentration has been found that is negatively dependent on the hyaluronan molecular mass; the higher the biopolymer molecular mass, the smaller the injected sample where the concentration effect should be taken into account for accurate evaluation of molecular mass distribution.

E. Orviský; L. Šoltés; S. Al Assaf

1994-01-01

189

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

PubMed

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

Simon, József; Felinger, Attila

2015-03-01

190

Application of hydrophilic interaction chromatography for the analysis of polar contaminants in food and environmental samples.  

PubMed

For the analysis of highly hydrophilic and polar compounds, Hydrophilic Interaction Chromatography (HILIC) has been established as a valuable complementary approach to reversed-phase liquid chromatography (RPLC). Moreover, the use of mobile phases with a high percentage of organic solvent in HILIC separation is beneficial for mass spectrometric (MS) detection, because of enhanced ionization which results in an increased sensitivity. In this review, various applications of HILIC are described for a number of environmental and food contaminants together with detailed methodological descriptions and the advantages or drawbacks of HILIC compared to other LC methods are critically discussed. In the first part of the review, an overview is given of the work that has been carried out with HILIC for the analysis of pharmaceuticals and pesticides in environmental samples. HILIC has shown its applicability for polar pharmaceuticals, such as antibiotics, estrogens and their metabolites, drugs of abuse, cytostatics, metformin and contrast agents. In the pesticide group, HILIC chromatography was helpful for polar phenylurea and organophosphorus pesticides. The second part of the review focuses on the analysis of antibiotic residues in food and feed with HILIC, while in the pesticide group, HILIC experiments have been reported for dithiocarbamates and quaternary ammonium compounds. The last chapter gives an overview of the analysis by HILIC of miscellaneous analytes in aquatic and food/feed samples. PMID:21316059

van Nuijs, Alexander L N; Tarcomnicu, Isabela; Covaci, Adrian

2011-09-01

191

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

192

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

193

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

194

Direct analysis of several Fusarium mycotoxins in cereals by capillary gas chromatography–mass spectrometry  

Microsoft Academic Search

A method for qualitative and quantitative analysis of Fusarium mycotoxins by gas chromatography–mass spectrometry (GC–MS) using cold on-column injection was improved. Eight typical mycotoxins, including deoxynivalenol (DON), 3-acetyldeoxynivalenol (3ADN), fusarenon-X (FX), diacetoxyscirpenol (DAS), 15-monoacetylscirpenol (15MAS), T-2 toxin (T-2), scirpentriol (SCT), and zearalenone (ZEA) were subjected to GC–MS without chemical derivatization by means of the on-column injection technique. Chromatographic separation of

Yoshiki Onji; Yoshinari Aoki; Naoto Tani; Kiyoshi Umebayashi; Yoshimi Kitada; Yoshiko Dohi

1998-01-01

195

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

Microsoft Academic Search

The potential of inductively coupled plasma-mass spectrometry (ICP-MS), which allows element-specific detection of heteroelements (e.g. Se and S) incorporated in protein structures, is highlighted for sensitive qualitative and quantitative protein analysis. ICP-MS coupled to separation techniques such as size exclusion chromatography and gel electrophoresis (via laser ablation) can be employed at different steps in the proteomic workflow. Special emphasis is

Dirk Schaumlöffel

2007-01-01

196

Multiresidue analysis of neonicotinoids by solid-phase extraction technique using high-performance liquid chromatography  

Microsoft Academic Search

For routine monitoring of pesticides, a multiresidue analysis through solid-phase extraction technique and using high-performance\\u000a liquid chromatography (HPLC) in cotton seed cake (CSC) has been developed. Extraction of fortified samples was carried out\\u000a with aqueous acetone under vacuum. The concentrated extract was loaded onto the solid-phase extraction units, preconditioned\\u000a with acetonitrile. The extraction units were then washed with hexane and

Chander Mohan; Yogesh Kumar; Jyotsana Madan; Navneet Saxena

2010-01-01

197

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

PubMed

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

Collins, Jennifer A; Janis, Gregory C

2012-01-01

198

Novel detection schemes and automated image analysis algorithms for planar chromatography and gel electrophoresis  

SciTech Connect

After a discussion of charge coupled devices and personal computer capabilities, examples of their applications involving novel analytical techniques are presented: laser-based indirect fluorometric detection in thin-layer chromatography; on-line detection of DNA and proteins in gel electrophoresis by uv absorption; automated image analysis for distortion compensation in sequencing gel electrophoresis; and expert systems for data acquisition to achieve constant signal-to-noise, with application to DNA sequencing slab gels.

Koutney, L.B.

1992-09-09

199

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

Microsoft Academic Search

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

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

2007-01-01

200

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

201

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

202

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 ...

203

Mathematical analysis of crossflow magnetically stabilized fluidized bed chromatography  

SciTech Connect

A mathematical model was developed for a crossflow magnetically stabilized fluidized bed (MSB) chromatograph with the pertinent continuity equations derived in partial differential equation form. In the case of linear adsorption isotherms, Fourier transform analysis yielded an expression for the resolution of the elution curves in terms of system parameters and operating conditions. Calculated predictions of the first moment and the variance of the elution curves were in good agreement with experimental results. A systematic parametric study conducted using the model showed that two factors, resistance to mass transfer and the width of the feed zone, have dominant effects on the size of the chomatographic bed. If smaller particles are utilized, which can be accomplished without excessive pressure drop by using an MSB, the mass-transfer resistance is reduced significantly. This allows an increase in the fraction of the bed width devoted to the feed zone and, thus, results in a lower solvent (carrier fluid) to feed ratio and more concentrated product solutions.

Pirkle, J.C. Jr.; Siegell, J.H. (Corporate Research Labs., Exxon Research and Engineering Co., Annandale, NJ (US))

1988-05-01

204

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

PubMed

Dried blood spots (DBS), a micro blood sampling technique, has recently gained interest in drug discovery and development due to its inherent advantages over the conventional whole blood, plasma or serum sample collection. Since the regulatory authorities have agreed to the use of blood as an acceptable biological matrix for drug exposure measurements, its applications have been extended not only to therapeutic drug monitoring but also to toxicokinetic and pharmacokinetic studies. The pharmaceutical industry is keen to promote DBS as a prominent tool in bioanalytical applications due to the financial, ethical and organizational issues involved in clinical trials. This could be accomplished due to the latest advances in modern analytical technology, particularly liquid chromatography-mass spectrometry. The present review discusses some of the emerging liquid chromatography-mass spectrometry technologies in improving DBS analysis for its innovative applications in the development of new drugs. PMID:24697571

Rao, Ramisetti Nageswara

2014-08-01

205

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

206

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

SciTech Connect

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

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

2012-04-01

207

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

208

Chemometric optimization of derivatization reactions prior to gas chromatography-mass spectrometry analysis.  

PubMed

Derivatization is a methodological technique that can be used to make an organic compound more suitable for qualitative and/or quantitative analysis (e.g. pharmaceuticals). However, many analysts try to avoid this analytical procedure as it is time-consuming and labour-intensive. On the other hand, an inter-laboratory study demonstrated that with regard to sensitivity and measurement uncertainty, gas chromatography coupled to mass-spectrometry was superior to liquid chromatography coupled to mass spectrometry for the trace analysis of organic compounds in matrices of greater complexity. In our previous paper (Kumirska et al., J. Chemometr. 25 (2011) 636-643) we suggested using principal component analysis (PCA) to optimize the derivatization of six compounds (5 oestrogenic steroids and diethylstilbestrol) prior to GC-MS analysis. In the present work we applied a highly sophisticated model - 24 pharmaceuticals derived from six classes of drugs. The efficiency of different derivatization reactions was evaluated by PCA and compared with that obtained from cluster analysis (CA), the latter method being applied in this context for the first time. Derivatization using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and 1% trimethylchlorosilane (TMCS) in pyridine and ethyl acetate (2:1:1, v/v/v) for 30min at 60°C was found to be optimal. The SPE-GC-MS method was also validated and successfully applied to the analysis of selected pharmaceuticals in wastewater and surface waters in Poland. PMID:23706154

Kumirska, Jolanta; Plenis, Alina; ?ukaszewicz, Paulina; Caban, Magda; Migowska, Natalia; Bia?k-Bieli?ska, Anna; Czerwicka, Ma?gorzata; Stepnowski, Piotr

2013-06-28

209

The analysis of paraquat in urine by high-speed liquid chromatography.  

PubMed

The paraquat content of urine can be directly determined by high-speed liquid chromatography using ultraviolet spectrophotometric detection. The method separates paraquat (and diquat) from the ultraviolet-absorbing components of urine and no extraction or pre-treatment of the sample is required prior to analysis. Concentrations down to 100 mug/1 of paraquat in urine were determined. Quantitative results are in good agreement with those obtained by a colorimetric method. Diquat does not interfere with the analysis of paraquat, and it would also be possible to analyse diquat in paraquat-containing urine. PMID:1202055

Pryde, A; Darby, F J

1975-12-10

210

The study of flow characteristic of gas-liquid two-phase flow based on the near-infrared detection device  

NASA Astrophysics Data System (ADS)

With the importance of the two-phase flow, many scholars pay attention on it; and for the so many parameters in the gas-liquid two-phase flow, flow characteristic is the basis. For the four flow patterns in the vertical direction, slug flow, bubbly flow, annular flow, and milk foam-like flow, the paper used the laser diode of 980nm and the silicon photodiode to detect the flow status. The absorption coefficients of the infrared in the gas and the liquid are very different; at the meantime, the infrared is affected by the interface obviously. As a result, it can reflect the fluctuation of the gas-liquid two-phase flow with the detection by the infrared. By analyzing the experiment data, four characteristic parameters are extracted, such as the average value, the variance, the kurtosis, and the frequency center of gravity. They can not only reflect the change of the different flow patterns, but also can reflect the fluctuation in the same flow pattern. The feature vector constituted of the four characteristic parameters can identify the flow pattern correctly in this system. What's more, it can achieve an accurate measurement of the real-time online, providing a basis for the other parameters' analysis in the gas-liquid two-phase flow.

Fang, Lide; Liang, Yujiao; Zhang, Yao; Zhang, Chen; Gao, Jingzhe

2014-04-01

211

Herbal medicine analysis by liquid chromatography/time-of-flight mass spectrometry.  

PubMed

The fact that the effects of herbal medicines (HMs) are brought about by their chemical constituents has created a critical demand for powerful analytical tools performing the chemical analysis to assure their efficacy, safety and quality. Liquid chromatography coupled to mass spectrometry (LC-MS) is an excellent technique to analyze multi-components in complex herbal matrices. Due to its inherent characteristics of accurate mass measurements and high resolution, time-of-flight (TOF) MS is well-suited to this field, especially for qualitative applications. The purpose of this article is to provide an overview on the potential of TOF, including the hybrid quadrupole- and ion trap-TOF (QTOF and IT-TOF), hyphenated to LC for chemical analysis in HMs or HM-treated biological samples. The peculiarities of LC-(Q/IT)TOF-MS for the analysis of HMs are discussed first, including applied stationary phase, mobile-phase selection, accurate mass measurements, fragmentation and selectivity. The final section is devoted to describing the applicability of LC-(Q/IT)TOF-MS to routine analysis of multi-components, including target and non-target (unknown) compounds, in herbal samples, emphasizing both the advantages and limitations of this approach for qualitative and quantitative purposes. The potential and future trends of fast high-performance liquid chromatography (HPLC) (e.g. rapid resolution LC and ultra-performance LC) coupled to (Q)TOF-MS for chemical analysis of HMs are highlighted. PMID:19501368

Zhou, Jian-Liang; Qi, Lian-Wen; Li, Ping

2009-10-30

212

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

213

Intact-protein trapping columns for proteomic analysis in capillary high-performance liquid chromatography.  

PubMed

A new type of monolithic trapping columns with high mechanical strength was prepared by thin-layer sol-gel coating method and applied to trapping intact proteins for on-line capillary liquid chromatography. Monolithic trapping columns were fabricated by entrapping C8 reversed-phase particles into the capillary columns through a sol-gel network, which was formed by hydrolysis and polycondensation of methyltriethoxysilane. Hundreds times of trapping/untrapping for intact proteins were carried out. The trapping columns showed long-term stability up to 300 bar. Recovery, loading capacity and reproducibility of trapping columns were evaluated using four proteins. The recovery of four protein mixtures for the C8 monolithic trapping columns was 99.3% on average. The loading capacity of 5 mm × 320 ?m i.d. C8 trapping columns for the protein mixtures was 30 ?g. Day-to-day relative standard deviation (RSD) values for recoveries of protein mixtures on the same C8 trapping column ranged from 2.34 to 5.87%, column-to-column RSD values were from 3.01 to 6.81%. The C8 trapping columns were used to trap normal mouse liver intact proteins in a capillary liquid chromatography system. Results demonstrated high efficiency of the monolithic trapping columns for trapping intact proteins for proteomic analysis in on-line capillary liquid chromatography system. PMID:20870240

Guan, Xia; Yan, Guoquan; Gao, Mingxia; Hong, Guangfeng; Deng, Chunhui; Zhang, Xiangmin

2010-10-29

214

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

Code of Federal Regulations, 2014 CFR

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

2014-07-01

215

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

216

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

Code of Federal Regulations, 2012 CFR

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

2012-07-01

217

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

Code of Federal Regulations, 2011 CFR

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

2011-07-01

218

Gas liquid sampling for closed canisters in KW Basin - test plan  

Microsoft Academic Search

Test procedures for the gas\\/liquid sampler. Characterization of the Spent Nuclear Fuel, SNF, sealed in canisters at KW-Basin is needed to determine the state of storing SNF wet. Samples of the liquid and the gas in the closed canisters will be taken to gain characterization information. Sampling equipment has been designed to retrieve gas and liquid from the closed canisters

Pitkoff

1995-01-01

219

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

E-print Network

phase flow at various pipe orientations are described with the aid of flow visual- ization. This chapter is helpful in understanding the impact of varying flow pat- terns, pipe diameter and pipe orientation#12;Chapter 4 Flow Patterns, Void Fraction and Pressure Drop in Gas-Liquid Two Phase Flow

Ghajar, Afshin J.

220

Gas/liquid sensing via chemotaxis of Euglena cells confined in an isolated micro-aquarium.  

PubMed

We demonstrate on-chip gas/liquid sensing by using the chemotaxis of live bacteria (Euglena gracilis) confined in an isolated micro-aquarium, and gas/liquid permeation through porous polydimethylsiloxane (PDMS). The sensing chip consisted of one closed micro-aquarium and two separated bypass microchannels along the perimeter of the micro-aquarium. Test gas/liquid and reference samples were introduced into the two individual microchannels separately, and the gas/liquid permeated through the PDMS walls and dissolved in the micro-aquarium water, resulting in a chemical concentration gradient in the micro-aquarium. By employing the closed micro-aquarium isolated from sample flows, we succeeded in measuring the chemotaxis of Euglena for a gas substance quantitatively, which cannot be achieved with the conventional flow-type or hydro-gel-type microfluidic devices. We found positive (negative) chemotaxis for CO2 concentrations below (above) 15%, with 64 ppm as the minimum concentration affecting the cells. We also observed chemotaxis for ethanol and H2O2. By supplying culture medium via the microchannels, the Euglena culture remained alive for more than 2 months. The sensing chip is thus useful for culturing cells and using them for environmental toxicity/nutrition studies by monitoring their motion. PMID:23934095

Ozasa, Kazunari; Lee, Jeesoo; Song, Simon; Hara, Masahiko; Maeda, Mizuo

2013-10-21

221

Liquid Layer Characteristics in Stratified Gas-Liquid Downflow: A Study of Transition to Wavy Flow  

Microsoft Academic Search

The purpose of this work was to study the transition from the smooth to the wavy stratified flow regime for various pipe inclination angles and liquid physical properties. The accurate characterization of both the structure of the gas-liquid interface and the flow field inside the liquid layer can improve our physical understanding of the mechanisms involved in the evolution of

J. S. Lioumbas; A. A. Mouza; S. V. Paras; A. J. Karabelas

2007-01-01

222

Simultaneous, sequential quantitative achiral-chiral analysis by two-dimensional liquid chromatography.  

PubMed

In general, chromatographic analysis of chiral compounds involves a minimum of two methods; a primary achiral method for assay and impurity analysis and a secondary chiral method for assessing chiral purity. Achiral method resolves main enantiomeric pairs of component from potential impurities and degradation products and chiral method resolves enantiomeric pairs of the main component and diastereomer pairs. Reversed-phase chromatographic methods are preferred for assay and impurity analysis (high efficiency and selectivity) whereas chiral separation is performed by reverse phase, normal phase, or polar organic mode. In this work, we have demonstrated the use of heart-cutting (LC-LC) and comprehensive two-dimensional liquid chromatography (LC × LC) in simultaneous, sequential achiral and chiral analysis and quantitation of minor, undesired enantiomer in the presence of major, desired enantiomer using phenylalanine as an example. The results were comparable between LC-LC and LC × LC with former offering better sensitivity and accuracy. The quantitation range was over three orders of magnitude with undesired D-phenylalanine detected at approximately 0.3% in the presence of predominant, desired L-phenylalanine (99.7%). The limit of quantitation was comparable to conventional high-performance liquid chromatography. A reversed-phase C18 achiral column in the primary and reversed-phase Chirobiotic Tag chiral column in the secondary dimension were used with a compatible mobile phase. PMID:22807357

Venkatramani, Cadapakam J; Wigman, Larry; Mistry, Kavita; Chetwyn, Nicholas

2012-07-01

223

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

224

Analysis of Phthalate Esters in Sediments from Dutch Rivers by means of High Performance Liquid Chromatography  

Microsoft Academic Search

Analysis of the phthalate esters dL(2-ethylhexyl) and di-n-butyl phthalate—DEHP and DBP, respectively—can conveniently be carried out by means of high-performance liquid chromatography in the system silica gel\\/n-hexane—dichloromethane (containing approx. 0.29.; of ethanol) (1:2, v\\/v). Detection is done by UV absorption spectrometry at 233 nm; the detection limit for both phthalates is approx. 10 ng.The procedure has been used for a

H. E. Schwartz; S. C. J. M. Anzion; S. H. P. M. Van Vliet; J. W. Copius Peerebooms; U. A. Th. Brinkman

1979-01-01

225

Analysis of felodipine by packed column supercritical fluid chromatography with electron capture and ultraviolet absorbance detection.  

PubMed

A reproducible and selective supercritical fluid chromatography (SFC) method was developed for the analysis of felodipine, a drug indicated for the treatment of hypertension. Methanol-modified carbon dioxide was employed as the SFC mobile phase with both electron capture detection (ECD) and multi-wavelength detection (MWD) being used simultaneously for analyte determination. Chromatography limit of detection (LOD) and limit of quantitation (LOQ), linear dynamic range (LDR) and injection precision were obtained in order to assess chromatographic and detector performance for both the SFC/MWD and SFC/ECD/MWD systems. The method was shown to be stability indicating since felodipine could be separated from its potential oxidative degradation product, H152/37, in under 6 min (felodipine k' = 2.44). Sample throughput was increased by 60% with the SFC assay vs LC. The optimized SFC method was shown to be equivalent to an existing LC/UV procedure for the analysis of a sustained-release tablet while realizing a 92% saving in disposable solvent waste. In order to achieve further solvent savings overall, supercritical fluid extraction (SFE) with 8% methanol-modified carbon dioxide as the extraction fluid was used to extract felodipine from a sustained-release tablet (as opposed to traditional solvent extraction). Comparable drug recoveries were obtained with SFE sample preparation technique when either SFC or LC extract analysis was utilized. PMID:7819374

Strode, J T; Taylor, L T; Howard, A L; Ip, D; Brooks, M A

1994-08-01

226

Modern developments in gas chromatography-mass spectrometry-based environmental analysis.  

PubMed

Gas chromatography coupled with mass spectrometry (GC-MS) continues to play an important role in the identification and quantification of organic contaminants in environmental samples. GC-MS is one of the most attractive and powerful techniques for routine analysis of some ubiquitous organic pollutants due to its good sensitivity and high selectivity and versatility. This paper presents an overview of recent developments and applications of the GC-MS technique in relation to the analysis in environmental samples of known persistent pollutants and some emerging contaminants. The use of different mass analysers such as linear quadrupole, quadrupole ion-trap, double-focusing sectors and time-of-flight analysers is examined. The advantages and limitations of GC-MS methods for selected applications in the field of environmental analysis are discussed. Recent developments in field-portable GC-MS are also examined. PMID:12877169

Santos, F J; Galceran, M T

2003-06-01

227

Elemental speciation analysis by multicapillary gas chromatography with microwave-induced plasma atomic spectrometric detection.  

PubMed

Multicapillary column gas chromatography (MC-GC)/microwave-induced plasma atomic emission spectrometry (MIP AES) was developed for fast speciation analysis of organotin compounds in the environment. Ethylated butyltin compounds could be separated isothermally within less than 30 s (instead of ?5-10 min) without sacrificing either the resolution or the sample capacity of conventional capillary GC with oven temperature gradient programming. Careful optimization of the pressure and temperature GC program allowed a comprehensive organotin speciation analysis including phenyltin compounds within less than 2.5 min, increasing the sample throughput 6-fold. Compatibility of MC-GC with an MIP atomic emission detector (MIP-AED) was discussed. MC-GC/MIP-AES was validated for the analysis of sediment (PACS-1 and BCR 462) and biological (NIES11) certified reference materials. PMID:21639152

Rodriguez Pereiro, I; Schmitt, V O; Lobi?ski, R

1997-12-01

228

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

PubMed

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

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

2013-03-15

229

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

SciTech Connect

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

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

2010-09-01

230

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

PubMed

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

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

2014-10-01

231

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

PubMed

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

Wylie, P L; Oguchi, R

1990-09-26

232

Separation of oligosaccharides by capillary supercritical fluid chromatography and analysis by direct coupling to high-resolution mass spectrometer: application to analysis of oligomannosidic N-glycans.  

PubMed

Supercritical fluid chromatography separations and supercritical fluid chromatography chemical ionization mass spectrometry analysis of permethylated and pertrimethylsilylated oligosaccharides are reported. Supercritical fluid chromatography was carried out using a DB-5 coated capillary column with carbon dioxide as a mobile phase. Peralkylated oligosaccharides were detected by flame ionization and by chemical ionization mass spectrometry using the GC interface. Analysis of permethylated malto-oligosaccharides, as well as oligomannosides from mannosidosis, was achieved by chemical ionization mass spectrometry with ammonia and provided the pseudo-molecular ions (M+H)+ and (M+NH4)+, in addition to some other fragments which allow interpretations of the structure of different oligosaccharides. The good resolution and sensitivity obtained emphasize the potential of supercritical fluid chromatography mass spectrometry for rapid separations and analysis of complex glycan mixtures. PMID:2327569

Leroy, Y; Lemoine, J; Ricart, G; Michalski, J C; Montreuil, J; Fournet, B

1990-02-01

233

Verification of Chemical Composition of Commercially Available Propolis Extracts by Gas Chromatography-Mass Spectrometry Analysis.  

PubMed

Abstract Propolis is a resin that is collected by honeybees from various plant sources. Due to its pharmacological properties, it is used in commercial production of nutritional supplements in pharmaceutical industry. In this study, gas chromatography-mass spectrometry was applied for quality control analysis of the three commercial specimens containing aqueous-alcoholic extracts of bee propolis. More than 230 constituents were detected in analyzed products, including flavonoids, chalcones, cinnamic acids and their esters, phenylpropenoid glycerides, and phenylpropenoid sesquiterpenoids. An allergenic benzyl cinnamate ester was also identified in all tested samples. This analytical method allows to evaluate biological activity and potential allergenic components of bee glue simultaneously. Studies on chemical composition of propolis samples may provide new approach to quality and safety control analysis in production of propolis supplementary specimens. PMID:25198412

Czy?ewska, Urszula; Kono?czuk, Joanna; Teul, Joanna; Dr?gowski, Pawe?; Pawlak-Morka, Renata; Sura?y?ski, Arkadiusz; Miltyk, Wojciech

2014-09-01

234

Analysis of fatty oil in Semen Ziziphi Spinosae by capillary gas chromatography.  

PubMed

A simple and fast capillary gas chromatographic (CGC) method with flame ionization detection is developed for the analysis of fatty oil in Semen Ziziphi Spinosae. After methyl-esterification, eight components are identified by gas chromatography-mass spectrometry. The derivatization condition is investigated in order to validate this method. Palmitic acid and stearic acid are quantitated simultaneously. The limits of detection are 5.024 microg/mL for palmitic acid and 6.957 microg/mL for stearic acid, respectively. The limits of quantitation are 16.76 microg/mL for palmitic acid and 23.19 microg/mL for stearic acid, respectively. The percent recoveries of palmitic and stearic acid are 97.4% and 96.6%. CGC is shown to be a quick and informative tool for the analysis of fatty oil in Semen Ziziphi Spinosae. PMID:12597596

Yu-Juan, Li; Kai-Shun, Bi; Xin-Miao, Liang; Hong-Bin, Xiao

2003-01-01

235

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

236

Rapid analysis of caffeine in ``smart drugs'' and ``energy drinks'' by microemulsion electrokinetic chromatography (MEEKC)  

E-print Network

chromatography (MEEKC) Eloisa Liotta a , Rossella Gottardo a , Catia Seri b , Claudia Rimondo b , Ivan Miksik c: gas chromatography­mass spectrometry (GC­MS) [10,11] and HPLC­MS [12,13]. Unfortunately Keywords: Caffeine Energy drink Smart drug Microemulsion electrokinetic chromatography A B S T R A C

Miksik, Ivan

237

Simultaneous analysis of cocaine and its metabolites in rat liver microsome s9 fraction by liquid chromatography-mass spectrometry.  

PubMed

A method utilizing liquid chromatography-mass spectrometry for the simultaneous analysis of cocaine and its in-vitro metabolites in rat liver micro some S9 fraction is described. Cocaine was incubated with rat liver micro some S9 fraction firstly, and then the incubation sample mixture was analyzed by liquid chromatography-mass spectrometry in full-scan mode. The main metabolites of cocaine were identified from the determination of molecular ions and the results of tandem mass spectrometry analysis. There were two metabolites were identified in the rat liver S9 fractions referring to the literature reports. PMID:25262520

Chen, Xueguo

2014-09-01

238

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

SciTech Connect

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

Not Available

1993-10-18

239

Static gas-liquid interfacial direct current discharge plasmas using ionic liquid cathode  

SciTech Connect

Due to the unique properties of ionic liquids such as their extremely low vapor pressure and high heat capacity, we have succeeded in creating the static and stable gas (plasmas)-liquid (ionic liquids) interfacial field using a direct current discharge under a low gas pressure condition. It is clarified that the ionic liquid works as a nonmetal liquid electrode, and furthermore, a secondary electron emission coefficient of the ionic liquid is larger than that of conventional metal electrodes. The plasma potential structure of the gas-liquid interfacial region, and resultant interactions between the plasma and the ionic liquid are revealed by changing a polarity of the electrode in the ionic liquid. By utilizing the ionic liquid as a cathode electrode, the positive ions in the plasma region are found to be irradiated to the ionic liquid. This ion irradiation causes physical and chemical reactions at the gas-liquid interfacial region without the vaporization of the ionic liquid.

Kaneko, T. [Department of Electronic Engineering, Tohoku University, Sendai 980-8579 (Japan); CREST/JST, Tokyo 102-0075 (Japan); Baba, K.; Hatakeyama, R. [Department of Electronic Engineering, Tohoku University, Sendai 980-8579 (Japan)

2009-05-15

240

U.S. crude oil, natural gas, and natural gas liquids reserves 1997 annual report  

SciTech Connect

This report presents estimates of proved reserves of crude oil, natural gas, and natural gas liquids as of December 31, 1997, as well as production volumes for the US and selected States and State subdivisions for the year 1997. 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 1997 is provided. 21 figs., 16 tabs.

NONE

1998-12-01

241

Routine application using single quadrupole liquid chromatography-mass spectrometry to pesticides analysis in citrus fruits.  

PubMed

A rapid and sensitive liquid chromatography-electrospray ionization-mass spectrometry method has been developed for the routine analysis of buprofezin, bupirimate, hexaflumuron, tebufenpyrad, fluvalinate and pyriproxyfen in citrus fruits. Extracts were obtained by matrix solid-phase dispersion (MSPD) using C18 as dispersant and dichloromethane-methanol (80:20, v/v) as eluent. Matrix effects were tested for all matrices by addition of standard to sample blank extracts (samples containing no detectable residues). Mean recoveries obtained at fortification levels between 0.01 and 5 mg kg(-1) were 57-97% with relative standard deviations (RSDs) from 5 to 19%. The limits of quantification (LOQ) were in the range of 0.01-0.2 mg kg(-1) and lower than maximum residue limits (MRLs) established by the Spanish legislation. The MSPD was compared with conventional ethyl acetate extraction, showing equivalent recoveries and precision. Although the sample is more concentrated (5-fold) by solid-liquid extraction (SLE) with ethyl acetate than by MSPD, LOQs obtained by both techniques, were almost equal, because MSPD reduces matrix effects, baseline noise, and interfering peaks from the matrix. The proposed method has been applied to the determination of selected pesticides in real samples. Liquid chromatography-tandem mass spectrometry (LC-MS-MS) with quadrupole ion trap (QIT) and triple quadrupole (TQ) have been used as confirmatory tool for positive samples according to a recent No. SANCO/10476/2003 European Union Guideline. PMID:16130755

Soler, Carla; Mañes, Jordi; Picó, Yolanda

2005-09-23

242

[Fast analysis of indole alkaloids from Evodiae fructus by supercritical fluid chromatography].  

PubMed

A fast chromatographic separation of indole alkaloids from Evodiae fructus was developed by supercritical fluid chromatography (SFC). The initial screening of four stationary phases was investigated with a standard mixture of evodiamine and rutaecarpine, and a complex sample of indole alkaloids prepared from Evodiae fructus as probes. Later, the effects of chromatographic parameters on separation were studied including injection volume, organic modifier, additive, temperature and back pressure. The injection volume had significant impact on the peak shape. With the additives in the mobile phase, slight changes in peak shape and retention time were observed in separation. Variation in organic modifier led to dramatic change in chromatographic behavior. Both decreased temperature and increased back pressure shortened the retention time. Finally, a fast analytical method using SFC, on a Waters ACQUITY UPC2 BEH column, methanol as modifier, under 35 degrees C and 2.07 x 10(7) Pa, was developed to separate a complex sample of indole alkaloids in less than 15 min. Another rapid approach for the separation of a complex sample of indole alkaloids was developed by using ultra-high performance liquid chromatography (UHPLC). As a result, SFC can be used in the separation of natural products, giving high performance, good resolution and fast analysis speed. The difference in selectivity with UHPLC can be used to the development of natural product separation. PMID:25185311

Li, Zhenyu; Fu, Qing; Li, Kuiyong; Liang, Tu; Jin, Yu

2014-05-01

243

Multiresidue analysis of pesticides in animal liver by gas chromatography using triple quadrupole tandem mass spectrometry.  

PubMed

Two methods for extracting organochlorine (OCs) and organophosphorus (OPs) pesticides from animal liver have been developed. The determination was carried out by gas chromatography with electron impact ionization tandem mass spectrometry (GC-(EI-)MS/MS) using a triple quadrupole (QqQ) analyzer. First, a liquid-solid extraction performed with a high-speed homogenizer (Polytron) using ethyl acetate as solvent, and a subsequent clean-up by gel permeation chromatography (GPC) was applied, determining 34 pesticides. Secondly, a matrix solid phase dispersion (MSPD) extraction with octadecylsilyl (C(18)) sorbent combined with a Florisil clean-up and ethyl acetate elution was performed, analyzing 25 compounds. These methodologies have been tested and compared in the sample pre-treatment due to the fatty nature of the matrix. The GPC method was finally selected and validated, yielding recoveries in the range 70-115%, with precision values expressed as relative standard deviation (RSD) lower or equal to 20%, at the spiking levels of 25 and 50 microg kg(-1), and limits of quantification (LOQs) lower than the maximum residue levels (MRLs) set by the European Union in animal products, except for isofenphos. Linearity was also studied ranging between 5 and 300 microg kg(-1) for most of pesticides. This method was applied to the analysis of real liver samples of chicken, pork and lamb. PMID:17289056

Frenich, Antonia Garrido; Bolaños, Patricia Plaza; Vidal, José Luis Martínez

2007-06-15

244

High-performance liquid chromatography-fluorescence analysis for indomethacin and metabolites in biological fluids.  

PubMed

A rapid and sensitive high-performance liquid chromatography-fluorescence method is described for the quantitative analysis of indomethacin and its metabolites in urine. A modified version is also shown for the detection of indomethacin in plasma. The method consists of a single extraction of an acid-buffered plasma sample or single extractions of two buffered aliquots in parallel of urine using ethyl acetate, followed by evaporation of the organic phase. Indomethacin (I) and the metabolite desmethylindomethacin (DMI) were deacylated to their fluorescent products, deschlorobenzoylindomethacin (DBI) and desmethyldeschlorobenzoylindomethacin (DMBI), respectively, prior to chromatography. The chromatographic phase utilized a reversed-phase C18-bonded column with a solvent system comprised of either 22.5% or 26% acetonitrile in 0.25% acetic acid. The elution times for indomethacin metabolites ranged from 12-26 min. The total DBI (including deacylated I) and DMBI (including deacylated DMI) in the extract were each determined using fluorometric detection, with excitation at 288 nm and emission at 390 nm (370 nm cutoff filter). An internal standard of indole-3-propionic acid was used for quantitation. The lower limit of sensitivity for I in plasma was 25 ng/ml. PMID:7085823

Bernstein, M S; Evans, M A

1982-04-16

245

New progress of the digital electrical capacitance tomography system for gas\\/liquid two phase flow  

Microsoft Academic Search

Electrical capacitance tomography (ECT) is gaining acceptance as a laboratory and industry tool to analyze gas\\/liquid two phase flow. To overcome the shortcomings of the existing analogue ECT system, a new 16-electrode digital electrical capacitance tomography system based on FPGA and DSP is designed. The new scheme can easily realize single frequency and multi-frequency excitation and demodulation. Furthermore, two kinds

Huaxiang Wang; Shan Xin; Xuehui Zhang

2009-01-01

246

Using in-line static mixers to intensify gas–liquid mass transfer processes  

Microsoft Academic Search

A novel static mixer design (screen-type elements) capable of taking advantage of the interfacial characteristics of industrial gas\\/liquid systems was developed. The interfacial area of contact, and volumetric oxygen transfer coefficient, were investigated using a 25.4mm pipe loop in which liquid superficial velocities of up to 2.0m\\/s (and gas holdups as high as 0.15) were tested. Volumetric mass transfer coefficients

A. M. Al Taweel; J. Yan; F. Azizi; D. Odedra; H. G. Gomaa

2005-01-01

247

Two-phase mass transfer in channel electrolyzers with gas-liquid flow  

Microsoft Academic Search

The electrochemical limiting current method was employed to study the mass transfer to a solid electrode in cocurrent gas-liquid flow through a vertical parallel-plate electrolyzer. Three systems were investigated: aqueous ferricyanide, aqueous ferricyanide containing a dispersion of nitrogen bubbles, and aqueous electrolyte containing a dispersion of oxygen bubbles in equilibrium with the liquid phase. The total mass-transfer rate was found

D. J. Economou; R. C. Alkire

1985-01-01

248

Gas–liquid two-phase flow in microchannels Part I: two-phase flow patterns  

Microsoft Academic Search

Capillary gas–liquid two-phase flow occurs in increasingly more modern industrial applications. The existing relevant data are limited and are inconsistent with respect to the reported flow patterns and their transition boundaries. A systematic experimental investigation of two-phase flow patterns in microchannels was the objective of this study.Using air and water, experiments were conducted in circular microchannels with 1.1 and 1.45mm

K. A. Triplett; S. M. Ghiaasiaan; S. I. Abdel-Khalik; D. L. Sadowski

1999-01-01

249

Gas-liquid flow patterns in microgravity: Effects of tube diameter, liquid viscosity and surface tension  

Microsoft Academic Search

Two-phase gas-liquid flow experiments have been developed for use on NASA microgravity aircraft to allow for high speed measurement of void fraction, liquid film thickness and pressure drop as well as high-speed photography of the flow features. Numerous experiments were conducted in order to determine the effect of liquid and gas superficial velocities, tube diameter, liquid viscosity and surface tension

W. S. Bousman; J. B. McQuillen; L. C. Witte

1996-01-01

250

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

Microsoft Academic Search

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

Hideo Ide; Ryuji Kimura; Masahiro Kawaji

2008-01-01

251

Studies of two-phase gas-liquid flow in microgravity  

Microsoft Academic Search

Two-phase gas-liquid flows are expected to occur in many future space operations. Due to a lack of buoyancy in the microgravity environment, two-phase flows are known to behave differently than those in earth gravity. Despite these concerns, little research has been conducted on microgravity two-phase flow and the current understanding is poor. This dissertation describes an experimental and modeling study

William Scott Bousman

1995-01-01

252

Low liquid loading gas-liquid two-phase flow in near- horizontal pipes  

Microsoft Academic Search

Low liquid loading gas-liquid two-phase flow in near- horizontal pipes has been studied both experimentally and theoretically. A new state-of-the-art, air-oil test facility was designed, constructed and operated. A transparent test section (50.1-cm ID x 19-m long) could be inclined within +\\/-2° from the horizontal. Mineral oil was used as the liquid phase (muL = 5.66 mPa.s, rhoL = 877

Weihong Meng

1999-01-01

253

Gas-liquid nucleation of nonideal binary mixtures. I. A density functional study  

Microsoft Academic Search

The binary gas–liquid nucleation of model Lennard-Jones mixtures is studied using density functional methods. It is shown that the ordinary ‘‘Ar’’–‘‘Kr’’ mixture shows stronger nonclassical nucleation behavior than previously thought. A more nonideal mixture is defined by modifying the usual mixing rules of the Lennard-Jones parameters. This fluid exhibits significantly stronger surface activity than the ordinary mixture. As with water\\/alcohol

Ari Laaksonen; David W. Oxtoby

1995-01-01

254

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

255

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

256

Ultrasound in gas-liquid systems: effects on solubility and mass transfer.  

PubMed

The effect of ultrasound on the pseudo-solubility of nitrogen in water and on gas-liquid mass transfer kinetics has been investigated in an autoclave reactor equipped with a gas induced impeller. In order to use organic liquids and to investigate the effect of pressure, gas-liquid mass transfer coefficient was calculated from the evolution of autoclave pressure during gas absorption to avoid any side-effects of ultrasound on the concentrations measurements. Ultrasound effect on the apparent solubility is very low (below 12%). Conversely ultrasound greatly improves gas-liquid mass transfer, especially below gas induction speed, this improvement being boosted by pressure. In typical conditions of organic synthesis: 323 K, 1100 rpm, 10 bar, k(L).a is multiplied by 11 with ultrasound (20 kHz/62.6 W). The impact of sonication is much higher on gassing out than on gassing in. In the same conditions, this enhancement is at least five times higher for degassing. PMID:18468473

Laugier, F; Andriantsiferana, C; Wilhelm, A M; Delmas, H

2008-09-01

257

Liquid and gas-liquid phase behavior in thermopneumatically actuated microvalves  

NASA Astrophysics Data System (ADS)

Thermopneumatically actuated microvalves rely on the thermal expansion of a gas, liquid, or gas-liquid mixture, hermetically sealed within an actuation cavity. This cavity is, typically, mechanically rigid on all sides, except for the side containing a mechanically flexible membrane, which is responsible for controlling the flow of fluid in the microvalve. Taken as a system, this actuation technique requires simultaneous consideration of the mechanical behavior of the membrane, the mechanical behavior ofthe control fluid, and the coupled thermal behavior ofthe valve and control fluid. Previous work has discussed the details of the liquid and gas-liquid behavior of the hermetically-sealed control fluid'. Figures ofmerit were developed for membrane behavior as a function ofYoung's modulus, valve structural parameters, and some of the thermodynamic properties of the thermopneumatic control fluid. However, the effects of initial thermodynamic state of the control fluid, external temperature (including thermal gradient), external pressure, and the temperature boundary condition at the control fluid's heat source were not considered. In this work, these effects are considered quantitatively. A model for the steady-state valve behavior (membrane deflection versus input heater power) is developed. The utility ofthis model in designing microvalves for gas and liquid flow control is also demonstrated.

Henning, Albert K.

1998-09-01

258

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

PubMed

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

Patsahan, O

2014-06-01

259

The kinetics of the reaction between CO2 and diethanolamine in aqueous ethyleneglycol at 298 K: a viscous gas—liquid reaction system for the determination of interfacial areas in gas—liquid contactors  

Microsoft Academic Search

The reaction between CO2 and diethanolamine (DEA) in aqueous ethyleneglycol (ETG) at 298 K has been studied over the complete composition range. The application of this reaction as a viscous gas—liquid system for the determination of interfacial areas in gas—liquid contactors by the chemical method is discussed. The reaction kinetics have been determined by mass transfer experiments of CO2 into

M. H. Oyevaar; R. W. J. Morssinkhof; K. R. Westerterp

1990-01-01

260

Analysis of flavonol aglycones and terpenelactones in Ginkgo biloba extract: A comparison of high-performance thin-layer chromatography and column high-performance liquid chromatography.  

PubMed

Advancements in automated high-performance thin-layer chromatography (HPTLC) have made it feasible to assess its use for the quantitative analysis of marker compounds in botanical preparations. We report here the findings of method comparisons for the terpenelactones and flavonol aglycones by column high-performance liquid chromatography (HPLC) with evaporative light scattering and UV detection, and HPTLC with a scanning densitometer. For the HPTLC assay of terpenelactones, total bilobalide, ginkgolide A, and ginkgolide B consistently achieved <70% of the total determined using HPLC, regardless of variations to postchromatographic derivatization time and temperature. Accuracy testing showed the possibility of a matrix interference. In contrast, a good relationship (95%) was determined between HPTLC and HPLC for determination of total flavonol glycosides (calculated from combined quercetin, kaempferol, and isorhamnetin) from an acid-hydrolyzed Ginkgo biloba L. (GBE) sample. The HPTLC flavonol aglycone method also performed well in terms of accuracy (overall average of 96% recovery for the 3 aglycones) and consecutive plate repeatability (overall percent relative standard deviation of 4.4). It is demonstrated that HPTLC can be a time-saving complement to HPLC for routine analysis of the flavonol glycosides in GBE. PMID:17955963

Gray, Dean E; Messer, Dale; Porter, Andrew; Hefner, Brian; Logan, Dama; Harris, Roger K; Clark, Alice P; Algaier, Joseph A; Overstreet, J Diane; Smith, Cynthia S

2007-01-01

261

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

262

Expanding the operational envelope of compact cylindrical cyclone gas/liquid separators using a variable inlet-slot configuration  

E-print Network

Despite the numerous advantages associated with using compact cylindrical cyclone gas/liquid separators, particularly for upstream production operations, the lack of a full understanding of the complex hydrodynamic process taking place in it and its...

Uvwo, Ighofasan

2006-04-12

263

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

264

Densitometric high performance thin-layer chromatography identification and quantitative analysis of psychotropic drugs.  

PubMed

A thin-layer chromatography (TLC)-densitometry method has been developed to identify and quantify haloperidol, amitriptyline, sulpiride, promazine, fluphenazine, doxepin, diazepam, trifluoperazine, clonazepam, and chlorpromazine in selected psychotropic drugs. Separation was performed on precoated silica gel 60 F254 TLC plates. Chromatograms were developed in various mobile phases, and 8 of 30 tested phases were selected based on spot location and developing time. The identification and quantification were carried out based on ultraviolet densitometric measurements at chosen wavelengths. In addition to retention coefficients, the absorption spectra recorded directly from chromatograms were also used in qualitative analysis. Under established experimental conditions, high sensitivity of the method was achieved. The limit of detection ranged from 0.009 to 0.260 microg, depending on the wavelength selected for measuring. A satisfactory recovery, ranging from 92.99 to 104.70%, was achieved for individual constituents. PMID:15759728

Ma?lanka, Anna; Krzek, Jan

2005-01-01

265

Spectral Analysis of Light Emitted by Streamers and Gas Chromatography in Liquid Dielectrics  

NASA Astrophysics Data System (ADS)

Spectral analysis of the light emitted by streamers during their propagation in liquid dielectrics reveals the presence of the H? line and C2 Swan bands as well as a continuum which corresponds to dissociation and fragmentation of liquid molecules and recombination of molecular fragments. Spectra of the emitted light vary according to polarity and streamer velocities. The more energetic the streamer, that is, the faster it is, the higher the characteristic lines emerging from the continuum. The above results confirm those obtained by gas chromatography conducted in a blend of mono- and dibenzyltoluene (M/DBT) and phenylxylylethane (PXE). Indeed, the latter shows the presence of decomposition products such as H2, CH4, C2H2, C2H4 and C2H6. However, hydrogen and acetylene are predominant. These gases may result from vaporization for slow bushlike streamers, whereas for fast filamentary ones the dominant mechanisms may be dissociation and ionization in the liquid phase.

Beroual, Abderrahmane

1993-12-01

266

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

267

A principal component analysis approach for developing retention models in liquid chromatography.  

PubMed

Three retention models for liquid chromatography are developed using principal component analysis (PCA). It is shown that they exhibit features similar to that of the model based on linear solvation energy relationship (LSER). However, the fitting performance of the PCA models is better than that of the LSER model, the performance of which can be considerably improved by the use of artificial neural networks. In addition, the possibility of using the proposed models as well as the LSER model to predict the retention times of solutes under chromatographic conditions at which these solutes have never been studied is also examined by means of three data sets of analytes consisting of non-polar compounds to polar compounds with a variety of functional groups. PMID:22771057

Nikitas, P; Pappa-Louisi, A; Tsoumachides, S; Jouyban, A

2012-08-17

268

Hydrophilic interaction liquid chromatography--mass spectrometry for the analysis of paralytic shellfish poisoning (PSP) toxins.  

PubMed

Hydrophilic interaction liquid chromatography (HILIC) was examined for the separation of paralytic shellfish poisoning (PSP) toxins using the stationary phase TSK-gel Amide-80. The parameters tested included type of organic modifier and percentage in the mobile phase, buffer concentration, pH, flow rate and column temperature. Using mass spectrometric (MS) detection, the HILIC column allowed the determination of all the major PSP toxins in one 30 min analysis with a high degree of selectivity and sensitivity. The high percentage of organic modifier in the mobile phase and the omission of ion pairing reagents, both favored in HILIC, provided limits of detection (LOD) in the range 50-100 nM in selected ion monitoring (SIM) mode on a single quadrupole LC-MS system. LOD in selected reaction monitoring (SRM) mode on a sensitive triple quadrupole system were as low as 5-30 nM. Excellent linearity of response was observed. PMID:16038209

Dell'Aversano, Carmela; Hess, Philipp; Quilliam, Michael A

2005-07-22

269

Identification of gas\\/liquid two-phase flow regime through ERT-based measurement and feature extraction  

Microsoft Academic Search

Gas\\/liquid two-phase flow is of great importance in various industrial processes. As the most important characteristic of a two-phase flow, the flow regime not only characterizes the flow condition in an explicit way, but also determines the measurement model in each measuring method. Based on the application of Electrical Resistance Tomography (ERT) to a gas\\/liquid two-phase flow on a vertical

Chao Tan; Feng Dong; Mengmeng Wu

2007-01-01

270

Application of electrical resistance tomography for slug flow measurement in gas\\/liquid flow of horizontal pipe  

Microsoft Academic Search

It is important to study the slug flow in a gas\\/liquid flow to achieve an in-depth understanding of the mixture flow and optimization of industrial processes. This paper presents a study of the slug flow measurement in gas\\/liquid flow of horizontal pipe. The application of ERT for slug flow measurement is demonstrated and described, including the visualization of slug size

Yanbin Xu; Huaxiang Wang; Ziqiang Cui; Feng Dong

2009-01-01

271

[Analysis of cis-9, trans-11-conjugated linoleic acid in milk fat by capillary gas chromatography].  

PubMed

Conjugated linoleic acid (CLA) is a term representing a mixture of positional and geometric isomers of octadecadienoic acid with a conjugated double bond system. Conjugated linoleic acid has attracted a great deal of interest among nutritionists because it is a natural fat component that appears to have a number of health improvement properties. The cis-9, trans-11-CLA is the major CLA isomer found in dairy products accounting for 75% to 90% of the total CLA in milk fat. A capillary gas chromatographic method equipped with a flame ionization detector for the analysis of the cis-9, trans-11-CLA in milk fat was developed. The cis-9, trans-11-CLA was extracted with hexane-isopropanol, methylated with methanol-sodium methylate and cis-9, trans-11-CLA was separated and quantified using gas chromatography. Retention time of the peaks was used for qualitative analysis, while external standard method was used for quantitative analysis. The recovery of the cis-9, trans-11-CLA was 100.26%. The relative standard deviation was 1.9% (n = 6). This method presented is advantageous for high precision, high sensitivity analysis with smaller sample size and simpler pretreatment. It would be of significance for analyzing the contents of other fatty acids in the milk and milk products. PMID:17288153

Wang, Xiaojing; Shen, Xiangzhen; Han, Hangru; Zhao, Ruqian; Chen, Jie

2006-11-01

272

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

PubMed

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

Maia, Miguel; Nunes, Fernando M

2013-01-15

273

ANALYSIS OF SEVEN CAPSAICINOIDS IN PEPPERS AND PEPPER-CONTAINING FOODS BY LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY  

Technology Transfer Automated Retrieval System (TEKTRAN)

Diverse procedures have been reported for the separation and analysis of secondary metabolites called capsaicinoids, pungent compounds in the fruit of various species of the Capsicum (Solanaceae) plant. To further improve the usefulness of high-performance liquid chromatography (HPLC) and liquid-ch...

274

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...

275

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

276

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

ERIC Educational Resources Information Center

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

Bailey, Leonard C.

1979-01-01

277

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...

278

RAPID ANALYSIS OF CYNANURIC ACID IN SWIMMING POOL WATERS BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY USING POROUS GRAPHITIC CARBON COLUMN  

EPA Science Inventory

An innovative approach is presented for reducing analysis times of cyanuric acid in swimming pool waters by high performance liquid chromatography (HPLC). The HPLC method exploits the unique selectivity of porous graphitic carbon (PGC) to fully resolve cyanuric acid from other p...

279

RAPID ANALYSIS OF CYANURIC ACID IN SWIMMING POOL WATERS BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY USING POROUS GRAPHITIC CARBON  

EPA Science Inventory

An innovative approach is presented for reducing analysis times of cynuric acid in swimming pool waters by high performance liquid chromatography (HPLC). The HPLC method exploits the unique selectivity of porous graphitic carbon (PGC) to fully resolve within 10 minutes cyanuric ...

280

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

281

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...

282

Comparison of ultra-high performance supercritical fluid chromatography and ultra-high performance liquid chromatography for the analysis of pharmaceutical compounds.  

PubMed

Currently, columns packed with sub-2 ?m particles are widely employed in liquid chromatography but are scarcely used in supercritical fluid chromatography. The goal of the present study was to compare the performance, possibilities and limitations of both ultra-high performance liquid chromatography (UHPLC) and ultra-high performance supercritical fluid chromatography (UHPSFC) using columns packed with sub-2 ?m particles. For this purpose, a kinetic evaluation was first performed, and van Deemter curves and pressure plots were constructed and compared for columns packed with hybrid silica stationary phases composed of 1.7 and 3.5 ?m particles. As expected, the kinetic performance of the UHPSFC method was significantly better than that of the UHPLC. Indeed, the h(min) values were in the same range with both strategies and were between 2.2 and 2.8, but u(opt) was increased by a factor of >4 in UHPSFC conditions. Another obvious advantage of UHPSFC over UHPLC is related to the generated backpressure, which is significantly lower in the presence of a supercritical or subcritical fluid. However, the upper pressure limit of the UHPSFC system was only ?400 bar vs. ?1000 bar in the UHPLC system, which prevents the use of highly organic mobile phases at high flow rates in UHPSFC. Second, the impact of reducing the particle size (from 3.5 to 1.7 ?m) was evaluated in both UHPLC and UHPSFC conditions. The effect of frictional heating on the selectivity was demonstrated in UHPLC and that of fluid density or decompression cooling was highlighted in UHPSFC. However, in both cases, a change in selectivity was observed for only a limited number of compounds. Third, various types of column chemistries packed with 1.7 ?m particles were evaluated in both UHPLC and UHPSFC conditions using a model mixture of acidic, neutral and basic compounds. It has been shown that more drastic changes in selectivity were obtained using UHPSFC columns compared to those obtained by changing UHPLC columns. In addition, there was a good complementarity between the two separation modes. Finally, by combining the use of small particles with supercritical fluids as a mobile phase, it was possible to achieve the analysis of pharmaceutical compounds in less than 1 min or to attain a peak capacity of more than 250 in approximately 40 min, both with a high degree of repeatability. PMID:23092872

Grand-Guillaume Perrenoud, Alexandre; Veuthey, Jean-Luc; Guillarme, Davy

2012-11-30

283

Extending the range of compounds amenable for gas chromatography-mass spectrometric analysis.  

PubMed

Gas chromatography-mass spectrometry (GC-MS) suffers from a major limitation in that an expanding number of thermally labile or low volatility compounds of interest are not amenable for analysis. We found that the elution temperatures of compounds from GC can be significantly lowered by reducing the column length, increasing the carrier gas flow rate, reducing the capillary column film thickness and lowering the temperature programming rate. Pyrene is eluted at 287 degrees C in standard GC-MS with a 30 m x 0.25 mm I.D. column with 1-microm DB5ms film and 1-ml/min He column flow rate. In contrast, pyrene is eluted at 79 degrees C in our "Supersonic GC-MS" system using a 1 m x 0.25 mm I.D. column with 0.1-microm DB5ms film and 100-ml/min He column flow rate. A simple model has been invoked to explain the significantly (up to 208 degrees C) lower elution temperatures observed. According to this model, every halving of the temperature programming rate, or number of separation plates (either through increased flow rate or due to reduced column length), results in approximately 20 degrees C lower elution temperature. These considerably lower elution temperatures enable the analysis of an extended range of thermally labile and low volatility compounds, that otherwise could not be analyzed by standard GC-MS. We demonstrate the analysis of large polycyclic aromatic hydrocarbons (PAHs) such as decacyclene with ten fused rings, well above the current GC limit of PAHs with six rings. Even a metalloporphirin such as magnesiumoctaethylporphin was easily analyzed with elution temperatures below 300 degrees C. Furthermore, a range of thermally labile compounds were analyzed including carbamates such as methomyl, aldicarb, aldicarbsulfone and oxamyl, explosives such as pentaerythritol tetranitrate, Tetryl and HMX, and drugs such as reserpine (608 a.m.u.). Supersonic GC-MS was used, based on the coupling of a supersonic molecular beam (SMB) inlet and ion sources with a bench-top Agilent 6890 GC plus 5972 MSD. The Supersonic GC-MS provides enhanced molecular ion without any ion source related peak tailing. Thus, the lower GC separation power involved in the analysis of thermally labile and low volatility compounds is compensated by increased separation power of the MS gained from the enhanced molecular ion. Several implications of these findings are discussed, including our conclusion that slower chromatography leads to better analysis of thermally labile compounds. PMID:12741601

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

2003-04-01

284

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

PubMed

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

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

2015-02-01

285

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

286

Quantitative determination of triterpenes from Amphiptherygium adstringens by liquid chromatography and thin-layer chromatography and morphological analysis of cuachalalate preparations.  

PubMed

Amphiptherygium adstringens (Anacardiaceae/Julianaceae), local name "cuachalalate," is used in folk medicine for the treatment of cholelithiasis, fevers, fresh wounds, hypercholesterolemia, gastritis, gastric ulcers, and cancer of the gastrointestinal tract. The development of column high-performance liquid chromatography-photodiode array detector (LC-PDA) and high-performance thin-layer chromatography (HPTLC)-densitometry methods for the determination of masticadienonic acid and 3-hydroxymasticadienonic acid in cuachalalate preparations is described in this paper. Good separation of the compounds could be achieved by both methods. Either might be preparable depending on the requirements. The LC separation was performed on a Phenomenex Synergi MAX-RP 80A reversed-phase column operated at 40 degrees C with detection at 215 nm. The plant materials were extracted with methanol by sonication. The triterpenes present in the plant material and commercial extracts were separated with an acetonitrile-water reagent alcohol isocratic system. The limit of detection was 0.1-0.2 microg/mL. The relative standard deviation values for the determination of triterpenes in plant extracts were less than 1.00%. This is the first report of an analytical method developed for the quantitative analysis of triterpenes from Amphiptherygium adstringens by LC-PDA and HPTLC. The stem bark showed higher amounts of triterpenes, and low amounts in root and stem root. The microscopic description of the crude drug of cuachalalate was also provided. PMID:16512221

Navarrete, Andres; Avula, Bharathi; Joshi, Vaishali C; Ji, Xiuhong; Hersh, Paul; Khan, Ikhlas A

2006-01-01

287

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

288

Enhancing concentration and mass sensitivities for liquid chromatography trace analysis of clopyralid in drinking water.  

PubMed

A theoretical treatment was developed and validated that relates analyte concentration and mass sensitivities to injection volume, retention factor, particle diameter, column length, column inner diameter and detection wavelength in liquid chromatography, and sample volume and extracted volume in solid-phase extraction (SPE). The principles were applied to improve sensitivity for trace analysis of clopyralid in drinking water. It was demonstrated that a concentration limit of detection of 0.02?ppb (?g/L) for clopyralid could be achieved with the use of simple UV detection and 100?mL of a spiked drinking water sample. This enabled reliable quantitation of clopyralid at the targeted 0.1?ppb level. Using a buffered solution as the elution solvent (potassium acetate buffer, pH 4.5, containing 10% of methanol) in the SPE procedures was found superior to using 100% methanol, as it provided better extraction recovery (70-90%) and precision (5% for a concentration at 0.1?ppb level). In addition, the eluted sample was in a weaker solvent than the mobile phase, permitting the direct injection of the extracted sample, which enabled a faster cycle time of the overall analysis. Excluding the preparation of calibration standards, the analysis of a single sample, including acidification, extraction, elution and LC run, could be completed in 1?h. The method was used successfully for the determination of clopyralid in over 200 clopyralid monoethanolamine-fortified drinking water samples, which were treated with various water treatment resins. PMID:22180193

Gu, Binghe; Meldrum, Brian; McCabe, Terry; Phillips, Scott

2011-12-19

289

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

290

Analysis of petroleum-contaminated soils by thin-layer chromatography with flame ionization detection  

SciTech Connect

Thin-layer chromatography with flame ionization detection (TLC-FID) offers a rapid and accurate method for the analysis of non-volatile organic materials. If the instrument is properly calibrated and the operational parameters are standardized, TLC-FID permits a rapid and accurate quantification of total petroleum hydrocarbons (TPH), and offers the possibility of separation and quantification of the major types of components in petroleum and petroleum products. Petroleum hydrocarbons from contaminated soil were extracted overnight with a mixture of chloroform:methanol. The analysis method consisted of spotting a small volume of the samples on silica-coated quartz rods followed by three chromatographic developments in solvent systems of increasing polarities. This series of chromatographic steps resulted in the complete separation of aliphatic hydrocarbons, aromatic hydrocarbons, resins and asphaltenes, starting from mixtures of the materials. This method also allows the quantification of aromatic and aliphatic hydrocarbons without interference from biogenic lipids present in the soil. A simplified version of this method allowed excellent separation of aliphatics plus aromatics (forming a single peak) from resins and asphaltenes. The instrument provides the complete analysis of 10 samples in about one hour after extraction. This rapid analytical tool is especially suited for synoptic studies or for the screening of a large number of samples prior to the consideration of more detailed and costly analyses.

Napolitano, G.E.; Richmond, J.E. [Oak Ridge National Lab., TN (United States)

1995-12-31

291

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

292

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

293

A simple ion chromatography method for inorganic anion analysis in edible seaweeds.  

PubMed

A new, simple, fast and sensitive ion chromatography (IC) method, for the simultaneous analysis of fluoride, chloride, nitrite, bromide, nitrate, phosphate and sulphate in edible seaweeds was developed and reported for the first time. The validation of the analytical method was studied in terms of linearity, sensitivity, precision and accuracy. All standard calibration curves showed very good correlation between anion peak area and concentration (r>0.999). Limits of detection and quantitation ranged between 0.002-0.05 mg/L and 0.01-0.1mg/L, respectively and indicated the high sensitivity of the method. Relative standard deviation values of repeatability and inter-day precision for standard anions with the same sample were less than 2%. Anion recoveries ranged from 97 to 113% for chloride and from 87 to 105% for sulphate, respectively and showed the fairly good accuracy of the method. The method was applied to the analysis of inorganic anions in brown and red edible seaweeds. Brown seaweeds were characterized by higher chloride content up to 33.7-36.9%, while red seaweeds were characterized by higher sulphate content (45-57%). Sulphate content in seaweeds is related to the presence of sulphated polysaccharides of biological importance. The method developed was well applicable to mineral anion analysis in edible seaweeds and shows suitability and reliability of use in other food samples of nutritional importance. PMID:20801334

Gómez-Ordóñez, Eva; Alonso, Esther; Rupérez, Pilar

2010-09-15

294

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

295

Combination of TLC blotting and gas chromatography-mass spectrometry for analysis of peroxidized cholesterol.  

PubMed

We have established a sensitive and convenient method for analysis of cholesterol hydroperoxides (Chol-OOHs) as trimethylsilyloxyl derivatives using diphenylpyrenylphosphine (DPPP)-thin-layer chromatography (TLC) blotting and gas chromatography-electron ionization-mass spectrometry/selected-ion monitoring (GC-EI-MS/SIM). Chol-OOH standards were prepared by photosensitized oxidation and azo radical-induced peroxidation of cholesterol. Trimethylsilyloxyl derivatives of cholesterol 5alpha-hydroperoxide (Chol 5alpha-OOH), cholesterol 7alpha-hydroperoxide (Chol 7alpha-OOH), and cholesterol 7beta-hydroperoxide (Chol 7beta-OOH) could be separated from one another in the SIM chromatogram using a fragment ion with elimination of trimethylsilanol from the molecular ion. This method was used to characterize peroxidized cholesterol from azo radical-exposed human low-density lipoprotein and UVA-irradiated human keratinocytes in the presence of hematoporphyrin. Finally, we succeeded in the quantification of each Chol-OOH isomer present in hairless mouse skin with and without UVA irradiation by use of beta-sitosterol hydroperoxide as internal standard. The accumulation of Chol 5alpha-OOH with Chol 7alpha/betaOOH in the skin indicates that singlet molecular oxygen ((1)O(2)) participated in the peroxidation of skin cholesterol, because Chol 5alpha-OOH is known to be a (1)O(2) specific cholesterol peroxidation product. We concluded that the combination of DPPP-TLC blotting and GC-EI-MS/SIM is useful for quantifying peroxidized cholesterol in biological samples and confirming the participation of (1)O(2) in oxidative stress. PMID:17701239

Minami, Yuko; Yokoi, Sayuri; Setoyama, Mari; Bando, Noriko; Takeda, Sayaka; Kawai, Yoshichika; Terao, Junji

2007-11-01

296

Glycomic Analysis by Glycoprotein Immobilization for Glycan Extraction and Liquid Chromatography on Microfluidic Chip  

PubMed Central

Glycosylation is one of the most common protein modifications and profoundly regulates many biological processes. Aberrant glycosylation is reported to associate with diseases such as cancers, human immunodeficiency virus, and immune disorders. It is considerably important to study protein glycosylation and the associated glycans for diagnostics and disease prognostics. Unlike other protein modifications, glycans attached to proteins are enormously complex. Therefore, the comprehensive analysis of glycans from biological or clinical samples is an unmet technical challenge. Development of the high-throughput method will facilitate the glycomics analysis. In this study, we developed a novel method for the high-throughput analysis of N-glycans from glycoproteins using glycoprotein immobilization for glycan extraction (GIG) coupled with liquid chromatography (LC) in an integrated microfluidic platform (chipLC). The separated glycans were then analyzed by mass spectrometry. Briefly, proteins were first immobilized on a solid support. Glycans on immobilized glycoproteins were modified on solid phase to increase the detection and structure analysis. N-Glycans were then enzymatically released and subsequentially separated by porous graphitized carbon particles packed in the same device. By applying the GIG-chipLC for glycomic analysis of human sera, we identified N-glycans with 148 distinct N-glycan masses. The platform was used to analyze N-glycans from mouse heart tissue and serum. The extracted N-glycans from tissues indicated that unique unsialylated N-glycans were detected in tissues that were missing from the proximal or distal serum, whereas common N-glycans from tissues and serum have mature and sialylated structures. The GIG-chipLC provides a simple and robust platform for glycomic analysis of complex biological and clinical samples. PMID:24111616

Yang, Shuang; Eshghi, Shadi Toghi; Chiu, Hanching; DeVoe, Don L.; Zhang, Hui

2013-01-01

297

Analysis of polychlorinated biphenyls in transformer oils by automated on-line coupling reversed phase liquid chromatography-gas chromatography using the through oven transfer adsorption desorption (TOTAD) Interface  

Microsoft Academic Search

An automated method for the direct analysis of polychlorinated biphenyls (PCBs) in transformer oil is presented. The proposed method uses the TOTAD (through oven transfer adsorption desorption) interface for the on-line coupling of reversed phase liquid chromatography and gas chromatography (RPLC-GC). In this fully automated system, the oil is injected directly with no sample pre-treatment step other than dilution with

José Manuel Cortés; Juan C. Andini; Rosa M. Toledano; Carlos Quintero; Jesús Villén; Ana Vázquez

2012-01-01

298

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

299

Hydrodynamic Chromatography  

NASA Astrophysics Data System (ADS)

Hydrodynamic chromatography (HDC) has experienced a resurgence in recent years for particle and polymer characterization, principally because of its coupling to a multiplicity of physical detection methods. When coupled to light scattering (both multiangle static and quasi-elastic), viscometric, and refractometric detectors, HDC can determine the molar mass, size, shape, and structure of colloidal analytes continuously and as a function of one another, all in a single analysis. In so doing, it exposes the analytes to less shear force (and, hence, less potential for flow-induced degradation) than in, for instance, size-exclusion chromatography. In this review, we discuss the fundamental chromatographic underpinnings of this technique in terms of retention, band broadening, and resolution, and we describe the power of multidetector HDC with examples from the recent literature.

Striegel, André M.; Brewer, Amandaa K.

2012-07-01

300

Gas Chromatography  

NASA Astrophysics Data System (ADS)

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

Qian, Michael C.

301

Rapid, quantitative analysis of americium, curium and plutonium isotopes in Hanford samples using extraction chromatography and precipitation plating  

Microsoft Academic Search

Recently developed methods for the rapid, quantitative analysis of americium (Am), curium (Cm), and plutonium (Pu) isotopes in Hanford soil, sludge, and waste-tank samples are described. After dissolution, dilutions are made as necessary based on alpha-energy analysis of a small aliquot of the original solution. Isotopic tracers are then added and Am-Cm and Pu are separated by extraction chromatography, coprecipitated

J. H. Kaye; R. S. Strebin; R. D. Orr

1995-01-01

302

Two-column sequential injection chromatography--new approach for fast and effective analysis and its comparison with gradient elution chromatography.  

PubMed

This work presents novel approach in low-pressure chromatography flow systems--two-column Sequential Injection Chromatography (2-C SIC) and its comparison with gradient elution chromatography on the same instrument. The system was equipped with two different chromatographic columns (connected to selection valve in parallel design) for isocratic separation and determination of all components in composed anti-inflammatory pharmaceutical preparation (tablets). The sample was first injected on the first column of length 30 mm where less retained analytes were separated and then the sample was injected on the second column of length 10 mm where more retained analytes were separated. The SIC system was based on a commercial SIChrom manifold (8-port high-pressure selection valve and medium-pressure syringe pump with 4 mL reservoir) (FIAlab, USA) with two commercially available monolithic columns the "first column" Chromolith Flash RP-18e (25 mm x 4.6 mm i.d. with guard column 5 mm x 4.6 mm i.d.) and the "second column" Chromolith RP-18e (10 mm x 4.6 mm i.d.) and CCD UV-vis detector USB 4000 with micro-volume 1.0 cm Z flow cell. Two mobile phases were used for analysis (one for each column). The mobile phase 1 used for elution of paracetamol, caffeine and salicylic acid (internal standard) was acetonitrile/water (10:90, v/v, the water part of pH 3.5 adjusted with acetic acid), flow rate was 0.9 mL min(-1) (volume 3.0 mL of mobile phase per analysis). The mobile phase 2 used for elution of propyphenazone was acetonitrile/water (30:70, v/v); flow rate was 1.2 mL min(-1) (volume 1.5 mL of mobile phase per analysis). Absorbance was monitored at 210 nm. Samples were prepared by dissolving of one tablet in 30% acetonitrile and 10 microL of filtered supernatant was injected on each column (2 x 10 microL). The chromatographic resolution between all compounds was >1.45 and analysis time was 5.5 min under the optimal conditions. Limits of detection were determined at 0.4 microg mL(-1) for paracetamol, at 0.5 microg mL(-1) for caffeine and at 0.7 microg mL(-1) for propyphenazone. The new two-column chromatographic set-up developed as an alternative approach to gradient elution chromatography shows evident advantages (time and solvent reduction more than one-third) as compared with single-column gradient SIC method with Chromolith Flash RP-18 (25 mm x 4.6 mm i.d. with guard column 5 mm x 4.6 mm i.d.). PMID:20457303

Chocholous, Petr; Satínský, Dalibor; Sklenárová, Hana; Solich, Petr

2010-05-23

303

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

304

[A liquid chromatography technique for routine determination of urinary estriol in human pregnancy (author's transl)].  

PubMed

A liquid chromatography procedure for routine determination of urinary estriol concentrations is described. After enzymic hydrolysis of a 1 ml sample, automatic extraction with chloroform/ethyl acetate, purification by chromatography on a disposable "minicolumn" of AG 1-X2, urinary estrogens are separated with normal phase column and isocratic elution with isooctane/ethyl acetate/methanol/water and the optical density at 280 nm is measured. The specificity is assessed by comparison of liquid chromatography with fluorometry and gas liquid chromatography. The technique is simple, rapid and quite suitable for routine determination. PMID:7258750

Habrioux, G

1981-01-01

305

Rapid liquid chromatography for paralytic shellfish toxin analysis using superficially porous chromatography with AOAC Official Method 2005.06.  

PubMed

The bioaccumulation of paralytic shellfish toxins in mussels, oysters, cockles, hard clams, razors, and king scallops is monitored in England, Scotland, and Wales by AOAC Official Method 2005.06 LC-with fluorescence detection (FLD). One of the commonly perceived disadvantages of using this method is the long turnaround time and low throughput in a busy laboratory environment. The chromatographic analysis of each sample typically utilizes a 15 min cycle time to achieve toxin oxidation product separation and column equilibration prior to subsequent analysis. A standard RP C18 analytical column, used successfully in recent years, achieves good separation with a long column lifetime. The analysis of a 40 sample qualitative screening batch takes approximately 18 h, including blanks, standards, and other QC samples. The availability of superficially porous column technology has offered the potential to reduce analysis time while retaining column performance on existing hardware. In this study, AOAC Official Method 2005.06 with LC-FLD was transferred to two different commercially available superficially porous columns, and the method performance characteristics were evaluated. Both columns separated all toxins adequately with cycle times less than half that of the existing method. Linearity for each toxin was acceptable up to two times the European maximum permitted limit of 800 microg di-HCl saxitoxin equivalent/kg flesh. LOD and LOQ values were substantially improved for the majority of toxins, with gonyautoxin 1&4 and neosaxitoxin showing up to a two- and fourfold improvement, respectively, depending on the column used. Quantification results obtained from parallel analysis of contaminated samples were acceptable on both columns. Comparative screen results gave a slight increase in the occurrence of contaminated samples, which was attributed to the improved detection limit for most toxins. Issues with rapidly increasing back pressure, however, were identified with both columns, with a limit of around 500 injections. This compares to the >3000 cycles routinely obtained with the standard RP-C18 HPLC columns currently in use. Overall, the gain achieved with these columns through shorter analysis time and improved analytical sensitivity is potentially of benefit in a high-throughput environment. For the routine high-throughput screening of shellfish samples, however, an improved column lifetime is desirable. PMID:22970577

Hatfield, Robert G; Turner, Andrew D

2012-01-01

306

Quantitative endogenous formate analysis in plasma using headspace gas chromatography without a headspace analyzer.  

PubMed

The objective was to develop a simple routine method for quantitative measurement of endogenous formic acid in plasma and whole blood using headspace gas chromatography-flame ionization detection. (GC-FID). Two-hundred microliters of sample was placed in a 1-mL glass vial. Fifty microliters of aqueous ethanol (10%) was added as an internal standard and a derivatizing agent. Ethylformate formation was enhanced by addition of 200 microL concentrated sulfuric acid as a catalyst. The vials were then sealed immediately and placed in a water bath for 15 min at 60 degrees C. One milliliter of this headspace gas was siphoned using a gas-tight syringe and injected into a GC-FID fitted with a capillary column. Ethanol eluted at approximately 3.0 min, and ethylformate eluted around 4.7 min. The limit of quantitation for ethylformate was 0.026 mmol/L, and the limit of detection was 0.020 mmol/L. Imprecisions for spiked plasma samples at 0.25 and 1 mmol/L were 10% and 9%, respectively and recoveries were at 100% and 108%, respectively. A simple, reliable, and highly specific headspace analysis method for quantifying endogenous formate without the use of a headspace analyzer was developed. This method enables the routine clinical analysis of formate in plasma and whole blood samples. PMID:17725880

Sokoro, AbdulRazaq; Lehotay, Denis; Eichhorst, Jeff; Treble, Ronald

2007-01-01

307

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

PubMed

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

Schaumlöffel, Dirk

2007-01-01

308

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

PubMed

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

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

2009-05-01

309

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

PubMed

Derivatization of steroids is typically required before analysis by gas chromatography/mass spectrometry (GC/MS); nevertheless, the derivatization process can often be time-consuming and irreproducible. Although several strategies have been employed to enhance this process, few have the potential of microwave-accelerated derivatization (MAD) to be more efficient than traditional thermal derivatization methods. MAD using a synthesis microwave system was evaluated and compared to traditional thermal derivatization methods in terms of yield, reproducibility, and overall analysis time. Parameters affecting MAD, including reaction temperature, time, and power, were systematically optimized for several silyl reagents (BSTFA with TMCS, MSTFA, and BSA) and other derivatization procedures (MOX reagent and MTBSTFA). MSTFA was found to derivatize best with the microwave, as demonstrated by the enhanced relative response factors (RRFs). BSTFA with TMCS, on the other hand, did not couple as well, but RRF values improved significantly upon addition of polar solvents. The rapid (1 min) derivatization reactions associated with MAD had comparable RRFs for all reagents with those obtained with thermal heating (>30 min). This study highlights the best methods for analyzing a comprehensive variety of steroids and also provides ideal strategies for MAD of steroids on an individual or class level. PMID:19606839

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

2009-08-15

310

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

311

Column chromatography analysis of brain tissue: an advanced laboratory exercise for neuroscience majors.  

PubMed

Neurochemical analysis of discrete brain structures in experimental animals provides important information on synthesis, release, and metabolism changes following behavioral or pharmacological experimental manipulations. Quantitation of neurotransmitters and their metabolites following unilateral drug injections can be carried out using standard chromatographic equipment typically found in most undergraduate analytical laboratories. This article describes an experiment done in a six session (four hours each) component of a neuroscience research methods course. The experiment provides advanced neuroscience students experience in brain structure dissection, sample preparation, and quantitation of catecholamines using high performance liquid chromatography (HPLC) and protein analysis using ultraviolet spectroscopic methods. The students are exposed to useful laboratory techniques such as standard solution preparation and calibration curve construction, centrifugation, quantitative pipetting, and data evaluation and graphical presentation. Typically, only students that participate in independent neuroscience research are familiar with these types of quantitative skills. The usefulness of this type of experimental design for understanding behavioral or pharmacological effects on neurotransmitter systems is emphasized through a final report requiring a comprehensive literature search. PMID:23492882

Church, William H

2005-01-01

312

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

313

Proteomic Analysis of the Organ of Corti Using Nanoscale Liquid Chromatography Coupled with Tandem Mass Spectrometry  

PubMed Central

The organ of Corti (OC) in the cochlea plays an essential role in auditory signal transduction in the inner ear. For its minute size and trace amount of proteins, the identification of the molecules in pathophysiologic processes in the bone-encapsulated OC requires both delicate separation and a highly sensitive analytical tool. Previously, we reported the development of a high resolution metal-free nanoscale liquid chromatography system for highly sensitive phosphoproteomic analysis. Here this system was coupled with a LTQ-Orbitrap XL mass spectrometer to investigate the OC proteome from normal hearing FVB/N male mice. A total of 628 proteins were identified from six replicates of single LC-MS/MS analysis, with a false discovery rate of 1% using the decoy database approach by the OMSSA search engine. This is currently the largest proteome dataset for the OC. A total of 11 proteins, including cochlin, myosin VI, and myosin IX, were identified that when defective are associated with hearing impairment or loss. This study demonstrated the effectiveness of our nanoLC-MS/MS platform for sensitive identification of hearing loss-associated proteins from minute amount of tissue samples. PMID:22942697

Peng, Hong; Liu, Miao; Pecka, Jason; Beisel, Kirk W.; Ding, Shi-Jian

2012-01-01

314

Analysis of folinic acid in human serum using high-performance liquid chromatography with amperometric detection.  

PubMed

An assay for the separation and quantification of folinic acid in serum was developed using high-performance liquid chromatography with electrochemical detection. Folinic acid was extracted from serum using a C18 minicolumn treated with dibasic ammonium phosphate. The drug was eluted from this column with methanol, which was evaporated under a nitrogen stream at 50 degrees. The mobile phase, pH 3.5 ammonium phosphate buffer-methanol-acetonitrile (93:4:3), was pumped at a flow rate of 3.0 ml/min. The recovery of folinic acid added to human serum was 101.11 +/- 8.5% (mean +/- SD). A plot of folinic acid peak height as a function of concentration was linear over the range of 2.5 X 10(-7) to 2.5 X 10(-6) M. Neither methotrexate nor other reduced folates interfered with the analysis of folinic acid. Sample preparation and analysis can be completed within 2 min of sample collection. PMID:6606033

Birmingham, B K; Greene, D S

1983-11-01

315

High-resolution fractionation after gas chromatography for effect-directed analysis.  

PubMed

This research presents an analytical technology for highly efficient, high-resolution, and high-yield fractionation of compounds after gas chromatography (GC) separations. The technology is straightforward, does not require sophisticated cold traps or adsorbent traps, and allows collecting large numbers of fractions during a GC run. The technology is based on direct infusion of a carrier solvent at the end of the GC column, where infusion takes place in the GC oven. Pentane and hexane used as carrier solvent showed good results. Acetonitrile also showed good results as a more polar carrier solvent. Development and optimization of the technology is described, followed by demonstration in a high-throughput effect directed analysis setting toward dioxin receptor bioactivity. The GC fractionation setup was capable of collecting fractions in the second range. As a result, fractionated compounds could be collected into one or two fractions when 6.5 s resolution fractionation was performed. Subsequently, mixtures containing polycyclic aromatic hydrocarbons, of which some are bioactive toward the dioxin receptor, were profiled with a mammalian gene reporter assay. After fractionation into 96-well plates, we used our new approach for direct cell seeding onto the fractions prior to assaying which allowed dioxin receptor bioactivity to be measured directly after fractionation. The current technology represents a great advance in effect directed analysis for environmental screening worldwide as it allows combining the preferred analytical separation technology for often non-polar environmental pollutants with environmentally relevant bioassays, in high resolution. PMID:23919657

Pieke, Eelco; Heus, Ferry; Kamstra, Jorke H; Mladic, Marija; van Velzen, Martin; Kamminga, Dik; Lamoree, Marja H; Hamers, Timo; Leonards, Pim; Niessen, Wilfried M A; Kool, Jeroen

2013-09-01

316

Interfacing multistage mass spectrometry with liquid chromatography or ion mobility separation for synthetic polymer analysis.  

PubMed

Synthetic polymers are naturally mixtures of homologs, even in pure form. More complexity is introduced by the presence of different comonomers, end groups and/or macromolecular architectures. The analysis of such systems is substantially facilitated by interfacing mass spectrometry (MS), which disperses based on mass, with an additional level of separation involving either interactive liquid chromatography (LC) or ion mobility (IM) spectrometry, both of which are readily coupled online with electrospray ionization and MS detection. IM-MS separates in the gas phase, post-ionization and, therefore, is ideally suitable for labile and reactive polymers. Its usefulness is illustrated with the characterization of non-covalent siloxane-saccharide complexes, metallosupramolecular assemblies and an air- and moisture-sensitive inorganic polymer, poly(dichlorophosphazene). Conversely, LC-MS which separates in solution phase, before ionization, is most effective for the analysis of polymeric mixtures whose components differ in polarity. Interactive LC conditions can be optimized to disperse by the content of hydrophobic units, as is demonstrated for amphiphilic polyether copolymers and sugar-based nonionic surfactant blends. Both LC-MS and IM-MS can be extended into a third dimension by tandem mass spectrometry (MS(2)) studies on select oligomers, in order to obtain insight into individual end groups and isomeric architectures, comonomer sequences and degree of substitution, for example, by hydrophobic functionalities. PMID:22641724

Scionti, Vincenzo; Katzenmeyer, Bryan C; Solak, Nilüfer; Li, Xiaopeng; Wesdemiotis, Chrys

2012-01-01

317

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. PMID:24420979

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

2014-11-01

318

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

NASA Astrophysics Data System (ADS)

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

Brauer, H.; Gaebelein, W.

1984-07-01

319

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

320

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

321

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

322

LETTER TO THE EDITOR: Ionic fluids: charge and density correlations near gas liquid criticality  

NASA Astrophysics Data System (ADS)

The correlation functions of an ionic fluid with charge and size asymmetry are studied within the framework of the random phase approximation. The results obtained for the charge-charge correlation function demonstrate that the second-moment Stillinger-Lovett (SL) rule is satisfied away from the gas-liquid critical point (CP) but not, in general, at the CP. However, in the special case of a model without size asymmetry the SL rules are satisfied even at the CP. The expressions for the density-density and charge-density correlation functions valid far from and close to the CP are obtained explicitly.

Patsahan, Oksana; Mryglod, Ihor; Caillol, Jean-Michel

2005-06-01

323

Ionic fluids: charge and density correlations near gas-liquid criticality.  

PubMed

The correlation functions of an ionic fluid with charge and size asymmetry are studied within the framework of the random phase approximation. The results obtained for the charge-charge correlation function demonstrate that the second-moment Stillinger-Lovett (SL) rule is satisfied away from the gas-liquid critical point (CP) but not, in general, at the CP. However, in the special case of a model without size asymmetry the SL rules are satisfied even at the CP. The expressions for the density-density and charge-density correlation functions valid far from and close to the CP are obtained explicitly. PMID:21690686

Patsahan, Oksana; Mryglod, Ihor; Caillol, Jean-Michel

2005-06-29

324

Identification of atmospheric organic sources using the carbon hollow tube-gas chromatography method and factor analysis  

SciTech Connect

Atmospheric organics were sampled and analyzed by using the carbon hollow tube-gas chromatography method. Chromatograms from spice mixtures, cigarettes, and ambient air were analyzed. Principal factor analysis of row order chromatographic data produces factors which are eigenchromatograms of the components in the samples. Component sources are identified from the eigenchromatograms in all experiments and the individual eigenchromatogram corresponding to a particular source is determined in most cases. Organic sources in ambient air and in cigaretts are identified with 87% certainty. Analysis of clove cigarettes allows the determination of the relative amount of clove in different cigarettes. A new nondestructive quality control method using the hollow tube-gas chromatography analysis is discussed.

Cobb, G.P.; Braman, R.S.; Gilbert, R.A. (Univ. of South Florida, Tampa (USA))

1989-04-15

325

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

326

Direct analysis of mannitol, lactulose and glucose in urine samples by high-performance anion-exchange chromatography with pulse amperometric detection. Clinical evaluation of intestinal permeability in human immunodeficiency virus infection.  

PubMed

Clinically, the ratio of lactulose/mannitol excretion in urine after administration of these non-metabolized sugars has been used to evaluate the extent of malabsorption and intestinal permeability disruption in several infections and nutritional diseases, including human immunodeficiency virus (HIV) infection. A range of methodologies have been reported to determine the lactulose/mannitol ratio, including enzymatic assay, gas-liquid chromatography (GC), thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). Most published methods involve tedious sample preparations, rendering them unsuitable for routine or automated clinical laboratory testing. We describe in this paper a method in which weak anion-exchange high-performance liquid chromatography in conjunction with a pulsed amperometric detector was used. It requires very simple sample preparation and avoids interference by other components present in the urine. The linear range of determination for mannitol, lactulose and glucose are up to 10 nmol, in a single injection. The limits of detection are 8, 12, 47 and 52 pmol, respectively, for mannitol, glucose, lactose and lactulose. The separation and quantification using this method are highly reproducible, yielding standard errors of less than 2.5% for retention times and less than 3.5% for quantitation. The ratios of lactulose/mannitol recovery in controls and in HIV-infected subjects with and without diarrhea showed striking differences, which are in close agreement with the published results derived with similar HPLC methods. PMID:8930758

Bao, Y; Silva, T M; Guerrant, R L; Lima, A M; Fox, J W

1996-10-11

327

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

328

Analysis of anthocyanins in commercial fruit juices by using nano-liquid chromatography-electrospray-mass spectrometry and high-performance liquid chromatography with UV-vis detector.  

PubMed

Nano-LC and conventional HPLC techniques were applied for the analysis of anthocyanins present in commercial fruit juices using a capillary column of 100 ?m id and a 2.1 mm id narrow-bore C(18) column. Analytes were detected by UV-Vis at 518 nm and ESI-ion trap MS with HPLC and nano-LC, respectively. Commercial blueberry juice (14 anthocyanins detected) was used to optimize chromatographic separation of analytes and other analysis parameters. Qualitative identification of anthocyanins was performed by comparing the recorded mass spectral data with those of published papers. The use of the same mobile phase composition in both techniques revealed that the miniaturized method exhibited shorter analysis time and higher sensitivity than narrow-bore chromatography. Good intra-day and day-to-day precision of retention time was obtained in both methods with values of RSD less than 3.4 and 0.8% for nano-LC and HPLC, respectively. Quantitative analysis was performed by external standard curve calibration of cyanidin-3-O-glucoside standard. Calibration curves were linear in the concentration ranges studied, 0.1-50 and 6-50 ?g/mL for HPLC-UV/Vis and nano-LC-MS, respectively. LOD and LOQ values were good for both methods. In addition to commercial blueberry juice, qualitative and quantitative analysis of other juices (e.g. raspberry, sweet cherry and pomegranate) was performed. The optimized nano-LC-MS method allowed an easy and selective identification and quantification of anthocyanins in commercial fruit juices; it offered good results, shorter analysis time and reduced mobile phase volume with respect to narrow-bore HPLC. PMID:21246720

Fanali, Chiara; Dugo, Laura; D'Orazio, Giovanni; Lirangi, Melania; Dachà, Marina; Dugo, Paola; Mondello, Luigi

2011-01-01

329

Wall-to-Bulk Mass Transfer in Co-current Gas Liquid Upflow Bubble Column Using Hourglass Promoters  

NASA Astrophysics Data System (ADS)

Limiting current measurements made at the point electrodes fixed flush with the inner wall of outer cylinder of an electrochemical cell with co-current gas-liquid upflow. The mass transfer coefficients were computed from the measured limiting currents. The system chosen was an electrolyte as liquid phase and nitrogen as gaseous phase. An equimolar solution of 0.01 N of potassium ferricyanide and ferrocyanide with 0.5 N sodium hydroxide was used as the liquid electrolyte. Data were obtained in the presence of an hourglass promoter internal with varied characteristic length and pitch values. The rod diameter was chosen as 1 cm. A longitudinal variation of mass transfer coefficient has been observed along the length of the test section. Therefore, average values of the kL were obtained and used. The kL values were found to increase with increasing gas and liquid velocities. An increase in pitch decreased the mass transfer coefficient. The characteristic length had no effect of kL. The data were correlated in terms of a jD-Re format of equation using regression analysis.

Suresh, S.; Murty, M. S. N.; Srinivas, B.; Ramesh, K. V.

2013-09-01

330

Measurement of bubble size distribution in a gas-liquid foam using pulsed-field gradient nuclear magnetic resonance.  

PubMed

Pulsed-field gradient nuclear magnetic resonance, previously used for measuring droplet size distributions in emulsions, has been used to measure bubble size distributions in a non-overflowing pneumatic gas-liquid foam that has been created by sparging propane into an aqueous solution of 1.5g/l (5.20mM) SDS. The bubble size distributions measured were reproducible and approximated a Weibull distribution. However, the bubble size distributions did not materially change with position at which they were measured within the froth. An analysis of foam coarsening due to Ostwald ripening in a non-overflowing foam indicates that, for the experimental conditions employed, one would not expect this to be a significant effect. It is therefore apparent that the eventual collapse of the foam is due to bubble bursting (or surface coalescence) rather than Ostwald ripening. This surface coalescence occurs because of evaporation from the free surface of the foam. An analytical solution for the liquid fraction profile for a certain class of non-overflowing pneumatic foam is given, and a mean bubble size that is appropriate for drainage calculations is suggested. PMID:20832808

Stevenson, Paul; Sederman, Andrew J; Mantle, Mick D; Li, Xueliang; Gladden, Lynn F

2010-12-01

331

Colloidal gas-liquid transition: tuning nucleation and growth by Critical Casimir forces  

NASA Astrophysics Data System (ADS)

The nucleation and growth of the liquid phase has been well studied in simulations, but direct experimental observations remain challenging. Here we present a detailed study of the colloidal gas-liquid transition induced by Critical Casimir forces that allow direct control over particle interactions via temperature-dependent solvent fluctuations. We show that with the direct control over particle interactions we can ``freeze'' a dilute colloidal gas into a dense colloidal liquid. By using dynamic light scattering to follow the evolution of liquid aggregates we observe three clearly distinct regimes: nucleation, interface limited- and diffusion limited growth. We elucidate these regimes directly in real space by using confocal microscopy. In the nucleation regime, we determine the Gibbs free energy, interfacial tension and chemical potential of the liquid aggregates directly from their size distribution. In the growth regime, we can directly follow the attachment of particles, and the collapse of liquid aggregates to large drops. Our critical Casimir colloidal system allows us to control all stages of nucleation and growth with temperature, thereby providing unprecedented insight into this gas-liquid transition.

Nguyen, Duc; Schall, Peter

2012-02-01

332

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

333

Experimental Study of Gas-Liquid Two-Phase Flow in Glass Micromodels  

NASA Astrophysics Data System (ADS)

To estimate the most important flow variables in reservoir engineering, such as the relative permeability, it is required to know with high precision, other variables such as saturation, pressure drop of each phase, and porous media data such as porosity and absolute permeability. In this study, experimental tests were performed inside a glass micromodel using gas-liquid two-phase flow in steady-state conditions. The liquid-phase flow and the pressure drop of the porous media were determined. Additionally, the flow development inside the porous media was visualized using a high-speed video camera system. These pictures were recorded at 500 fps, and they were used to compute the phase saturation and the gas velocity in the glass micromodel. The visualization was performed in three regions of the glass micromodel demonstrating that saturation gradients were not present. The effect of the capillary number was studied over the gas-liquid relative permeability curves and on the flow mechanisms. It was concluded that high flow rates minimize edge effects, that the capillary number modifies the relative permeability values and the flow patterns inside the micromodel, and that the high-speed visualization is an efficient and accurate technique to determine saturation values and to study the flow patterns in transparent porous media such as glass micromodels.

Gutiérrez, B.; Juarez, F.; Ornelas, L.; Zeppieri, S.; de Ramos, A. López

2008-12-01

334

Calibration of solid-phase micro-extraction for quantitative analysis by gas chromatography.  

PubMed

Calibration of SPME by the injection of liquid standard solution is a common method for SPME quantitative analysis by gas chromatography. The feasibility of this calibration method relies on the assumption that sample transfer efficiencies are the same for both the liquid injection and the SPME fiber injection. Sample transfer efficiencies for liquid injection and SPME fiber injection were studied in this paper. The results showed that the sample transfer efficiency for liquid injection was affected by several factors, such as the dimensions of the liner, the presence of the wool, and the temperature of the injector. The sample transfer efficiency for SPME fiber injection was affected by the cross-sectional area of the space between the column and the liner, the carrier gas flow rate, and the length of the column inside the liner. An equation was proposed to estimate the sample loss rate for SPME injection. It was found that the use of a direct injection (DI) liner and program temperature vaporizing provides high sample transfer efficiencies, for both liquid injection and SPME fiber injection. When a common SPME straight liner is used, large outer diameter (o.d.) pre-column will help to achieve high sample transfer efficiency. PMID:16298180

Ouyang, Gangfeng; Chen, Yong; Setkova, Lucie; Pawliszyn, Janusz

2005-12-01

335

Direct analysis of several Fusarium mycotoxins in cereals by capillary gas chromatography-mass spectrometry.  

PubMed

A method for qualitative and quantitative analysis of Fusarium mycotoxins by gas chromatography-mass spectrometry (GC-MS) using cold on-column injection was improved. Eight typical mycotoxins, including deoxynivalenol (DON), 3-acetyldeoxynivalenol (3ADN), fusarenon-X (FX), diacetoxyscirpenol (DAS), 15-monoacetylscirpenol (15MAS), T-2 toxin (T-2), scirpentriol (SCT), and zearalenone (ZEA) were subjected to GC-MS without chemical derivatization by means of the on-column injection technique. Chromatographic separation of the toxins extracted from barley was achieved as a single peak, and the specific EI mass spectra of each toxin were obtained. The fatty acids in the extract that interfere with measurements of the toxins on the gas chromatogram were removed by precipitation as an insoluble metal soap with zinc acetate. Additional clean-up was accomplished using a Bond Elut Florisil cartridge. The quantitative detection limit in barley ranged from 0.1 to 0.5 micrograms/g. The average recoveries of 93.1% for DON, 3ADN, 15MAS, DAS, T-2 and ZEA, and 46.0% for FX and SCT added to barley at the level of 1 microgram/g were obtained. PMID:9718707

Onji, Y; Aoki, Y; Tani, N; Umebayashi, K; Kitada, Y; Dohi, Y

1998-07-31

336

Simultaneous analysis of serotonin, melatonin, piceid and resveratrol in fruits using liquid chromatography tandem mass spectrometry.  

PubMed

An analytical method was developed for the simultaneous quantification of serotonin, melatonin, trans- and cis-piceid, and trans- and cis-resveratrol using reversed-phase high performance liquid chromatography coupled to mass spectrometry (HPLC-MS) with electrospray ionization (ESI) in both positive and negative ionization modes. HPLC optimal analytical separation was achieved using a mixture of acetonitrile and water with 0.1% formic acid as the mobile phase in linear gradient elution. The mass spectrometry parameters were optimized for reliable quantification and the enhanced selectivity and sensitivity selected reaction monitoring mode (SRM) was applied. For extraction, the direct analysis of initial methanol extracts was compared with further ethyl acetate extraction. In order to demonstrate the applicability of this analytical method, serotonin, melatonin, trans- and cis-piceid, and trans- and cis-resveratrol from 24 kinds of commonly consumed fruits were quantified. The highest serotonin content was found in plantain, while orange bell peppers had the highest melatonin content. Grape samples possessed higher trans- and cis-piceid, and trans- and cis-resveratrol contents than the other fruits. The results indicate that the combination of HPLC-MS detection and simple sample preparation allows the rapid and accurate quantification of serotonin, melatonin, trans- and cis-piceid, and trans- and cis-resveratrol in fruits. PMID:21570690

Huang, Xin; Mazza, Giuseppe

2011-06-24

337

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

PubMed

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

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

2014-11-01

338

[Honey adulteration detection using liquid chromatography/ elemental analysis-isotope ratio mass spectrometry].  

PubMed

A new method for honey adulteration detection using liquid chromatography/elemental analysis-isotope ratio mass spectrometry (LC/EA-IRMS) was developed. Based on the individual delta13C values detected for 38 authentic honey samples, the limits for the authentic honey samples were proposed: the delta13C difference between protein and honey (Deltadelta13C(P-H)) should be higher or equal to than -0.95 per thousand, the delta13C difference between fructose and glucose (Deltadelta13C(F-G)) should be from -0.64 per thousand to 0.53 per thousand, and the maximum difference of delta13C values between all the components (Deltadelta13Cmax) should be lower than 2.09 per thousand. Based on the above criteria, the 58 positive samples spiked with C4 or C3 plant sugar syrup were confirmed by LC/EA-IRMS method from 150 commercial honey samples, while only 7 samples spiked with C4 plant sugar syrup were confirmed by the official EA-IRMS method. The proposed method represents a significant improvement in comparing with the official EA-IRMS method. PMID:21574394

Fei, Xiaoqing; Wu, Bin; Sehn, Chongyu; Ding, Tao; Li, Lihua; Lu, Ying

2011-01-01

339

Purification and analysis of mono-PEGylated HSA by hydrophobic interaction membrane chromatography.  

PubMed

We discuss the purification of mono-PEGylated HSA by hydrophobic interaction membrane chromatography. The hydrophobicity difference between the different fractionated species was induced by the addition of a lyotropic salt that caused phase transition of PEG (hydrophilic under normal condition) to a mildly hydrophobic form. The HSA PEGylation reaction mixture was mixed with lyotropic salt and passed through a stack of hydrophilized polyvinylidene fluoride membrane discs. Unmodified HSA was obtained in the flow through, while the PEGylated forms of the protein bound to the membrane and could be eluted by reducing the salt concentration. Among the three major PEGylated forms of HSA present in the feed (i.e. mono-, di-, and tri-), mono-PEGylated HSA was eluted first and could be resolved from the others. The purified material was analyzed by SDS-PAGE, dynamic light scattering, and SEC combined with multi-angle light scattering. All these analytical techniques indicated the presence of species that has a molar mass consistent with mono-PEGylated HSA. A scaled-down version of the membrane chromatographic methods could be used for the rapid and sensitive analysis of PEGylated proteins. PMID:24106126

Shang, Xiaojiao; Wittbold, William; Ghosh, Raja

2013-12-01

340

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

PubMed Central

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

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

2014-01-01

341

Analysis of the estrogenic components in kudzu root by bioassay and high performance liquid chromatography.  

PubMed

The estrogenic activity of the Chinese herb kudzu root was investigated by a recombinant yeast screening assay (YES). Isoflavones are the main components in the plant, of which puerarin is the most abundant one. The kudzu root extract was separated into four fractions according to the polarity. The crude extract and its sub-fractions, except the water fraction, showed clear estrogenic activity and the potencies were in the range of 10(-3) to 10(-1)g/l. The ligand potency was used to compare the estrogenic activity of these fractions. The crude extract and its sub-fractions were further analyzed by high performance liquid chromatography (HPLC) to correlate the activity and the active components. Bioassay and chemical analysis showed that theoretical estrogenic activity expressed as equivalent 17beta-estradiol concentration or the cumulative effects are comparable to that experimentally determined by YES. The results showed that the high content of isoflavones as well as the high estrogenic activity could make kudzu root extract an interesting candidate for hormone replacement therapy. PMID:15857757

Zhang, Yan; Chen, Jiping; Zhang, Chunzhi; Wu, Wenzhong; Liang, Xinmiao

2005-03-01

342

Gas chromatography with mass spectrometry analysis of phosphoserine, phosphoethanolamine, phosphoglycerol, and phosphate.  

PubMed

A new, rapid, sensitive, robust, and reliable method has been developed for the qualitative analysis of phosphoserine, phosphoethanolamine, phosphoglycerol, and phosphate using gas chromatography with mass spectrometry and two-step trimethylsilylation. The method employs hexamethyldisilazane for silylation of the phosphate and hydroxyl groups in the first phase and bis(trimethylsilyl)trifluoroacetamide for silylation of the less-reactive amino groups in the second phase. This order is of key importance for the method because of the different reactivities of the two reagents and the mechanism of derivatization of the active groups of the analytes. Trimethylsilylated derivatives of the analytes were identified on the basis of their retention times and mass spectra. The probable structures of the major fragments were identified in the spectra of the trimethylsilylated derivatives and characteristic m/z fragments were selected for each analyte. Fragments with m/z 73 and 299 occurred in the spectra of all the analytes. The characteristic retention data were employed to calculate the retention indices of the individual silylated phosphorylated substances in the hydrocarbon range C12 -C19 for the DB-5ms column. The method was employed to measure the polar fraction of the hydrolysate of the cytoplasmic membrane of Bacillus subtilis. The detection limits vary between 5 ?g/mL (trimethylsilylated phosphate) and 72 ?g/mL (trimethylsilylated phosphoethanolamine). PMID:25359098

Bierhanzl, Václav Mat?j; ?abala, Radomír; Ston, Martin; Kubinec, Róbert; Szabó, Alexandra Hengerics; Podolec, Peter

2015-01-01

343

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

PubMed

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

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

2009-08-15

344

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

345

Simultaneous Determination of Diethylstilbestrol, Testosterone, and 17?-Estradiol Residues in Meat and Meat Products Using Gas–Liquid Chromatography  

Microsoft Academic Search

A gas-chromatographic procedure was developed for the simultaneous determination of hormones (diethylstilbestrol, testosterone, and 17ß-estradiol) as heptafluorobutyric anhydride derivatives. A mid-polarity HP-50 capillary column (silicone liquid phase containing 50% phenyl groups) and an electron-capture detector were used. The detection limits were 0.3–0.6 mg in a sample of 2 µL. The applicability of this procedure for the determination of hormone residues

E. N. Barkatina; S. V. Volkovich; O. N. Venger; V. I. Murokh; N. D. Kolomiets; O. V. Shulyakovskaya

2001-01-01

346

Kinetic study of the mutarotation of D-glucose in concentrated aqueous solution by gas-liquid chromatography  

Microsoft Academic Search

Growth is the most important step of industrial seeded crystallisation. The overall laws that govern ?-D-glucose monohydrate crystal growth should depend upon mutarotation. This parameter could become a limiting factor, as it is the case for diffusion or the integration of molecules at the surface of crystal. Consequently, it was considered essential to obtain additional information on mutarotation kinetics, under

N Le Barc'H; J. M Grossel; P Looten; M Mathlouthi

2001-01-01

347

Investigations on 1-Azabicyclic Compounds. 25. Stereochemistry, Hydrogen Bonds, and Gas-Liquid Chromatography of Pyrrolizidine Alcohols  

Microsoft Academic Search

Data have been summarized of several studies on the separation of isomeric pyrrolizidine alcohols by GLC using liquid polar stationary phases. It was shown that the order of emergence of isomers from the chromatographic column is determined to a significant extent by competition of intermolecular hydrogen bonds formed in the sorbate-sorbent systems and intramolecular hydrogen bonds in the molecules of

I. M. Skvortsov

2003-01-01

348

Simultaneous determination of soluble sugars and organic acids as their trimethylsilyl derivatives in apricot fruits by gas-liquid chromatography  

Microsoft Academic Search

The aim of this study was to determine a reliable procedure for the quantification of organic acids, alcohol soluble sugars and sugar alcohols in fruit fresh by means of a rapid GLC method, without resorting to methoximation of sugars and employing apricot as a model. The use of two internal standards, an accurate derivatization and a proper calibration of the

Francesco Bartolozzi; Gianpaolo Bertazza; Daniele Bassi; Graziella Cristoferi

1997-01-01

349

Evaluation of a commercial gas chromatography/matrix isolation-infrared spectrometer for quantitative analysis of priority pollutants  

SciTech Connect

Gas chromatography/matrix isolation-infrared spectrometry (GC/MI-IR) is being applied to many analyses normally done by gas chromatography/mass spectrometry. Qualitatively, the infrared spectra of matrix-isolated compounds contain much information about their structure. The information obtained from the infrared spectrum is complementary to the information obtained from mass spectrometry. The technique of GC/MI-IR should also be useful as a quantitative detector. In this study, the utility of a commercial GC/MI-IR for quantitative trace organic analysis was evaluated. Results indicate that the reproducibility of the commercial instrument is only suitable for semiquantitative analysis. The precision of the commercial instrument might be improved by redesign of its open-split interface. 12 refs., 39 figs., 9 tabs.

Schneider, J.F.; Schneider, K.R.; Spiro, S.E.

1989-10-01

350

Analysis of atmospheric aerosols by particle-induced X-ray emission, instrumental neutron activation analysis, and ion chromatography  

NASA Astrophysics Data System (ADS)

Particle-induced X-ray emission (PIXE), ion chromatography (IC), and occasionally also instrumental neutron activation analysis (INAA) were used in combination for the analysis of atmospheric aerosol samples that were collected on Nuclepore polycarbonate filters. A comparison of the results enabled us to evaluate the matrix effects (i.e., particle size effects) of the PIXE analysis for the light elements and to assess the water-solubility and/or speciation of a number of elements (e.g., S, K, Ca). Results are presented from several measurement campaigns at urban and forested sites in Europe, whereby PM10 or PM2.5 filter samples were taken. From the PIXE and IC results for a 2003 summer campaign at the K-puszta site in Hungary, it was estimated that organosulphates could be responsible for 20% of the total sulphur concentration and 30% of the organic aerosol in PM10. The comparison of the IC and PIXE data for K and Ca from the various sites indicated that most of the Ca was water-soluble (the mineral dust Ca was presumably mostly present as calcite, and perhaps also in part as gypsum); in contrast, for K, only half of it was typically water-soluble, indicating that it was to a large extent associated with insoluble mineral dust. Exceptions, with almost fully water-soluble K, were found for samples that were substantially impacted by biomass burning.

Maenhaut, Willy; Raes, Nico; Wang, Wan

2011-11-01

351

A rapid and simplified method of analysis by thin-layer chromatography using microchromatoplates  

Microsoft Academic Search

Summary A simple procedure is described for thin-layer chromatography on small lantern slides and microscope slides. By using microscope cover slips, analyses of organic mixtures may be completed within three to five minutes.

James J Peifer

1962-01-01

352

CHROMATOGRAPHY B: BIOMEDICAL APPLICATIONS  

E-print Network

JOURNAL OF CHROMATOGRAPHY B: BIOMEDICAL APPLICATIONS ELSEVIER Journal of Chromatography B, 653 Republic blnstitute of Forensic Medicine, University of Verona, Verona, Italy (First received October 8th on the analysis of drugs in animal 0378~4347/94/$07.00 0 1994 Elsevier Science B.V. All rights reserved SSDZ 0378

Miksik, Ivan

353

Advanced proteomic liquid chromatography  

SciTech Connect

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

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

2012-10-26

354

Analysis and screening for mycotoxins and other secondary metabolites in fungal cultures by thin-layer chromatography and high-performance liquid chromatography  

Microsoft Academic Search

Methods for the screening of fungal cultures for toxic secondary metabolites are reviewed. Thin layer Chromatography (TLC) and high-performance liquid Chromatography (HPLC) are good general analytical methods for secondary metabolites in unpurified extracts. The combination of normal phase TLC using different chemical spray reagents with reversed phase HPLC, using alkylphenone retention indices and diode array detection, is a powerful technique

Jens C. Frisvad; Ole Filtenborg; Ulf Thrane

1989-01-01

355

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

EPA Science Inventory

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

356

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

Microsoft Academic Search

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

M. A. Poirier; A. E. George

1982-01-01

357

Analysis of small droplets with a new detector for liquid chromatography based on laser-induced breakdown spectroscopy  

Microsoft Academic Search

The miniaturization of analytical techniques is a general trend in speciation analytics. We have developed a new analytical technique combining high pressure liquid chromatography (HPLC) with laser-induced breakdown spectroscopy (LIBS). This enables a molecule-specific separation followed by an element-specific analysis of smallest amounts of complex samples. The liquid flow coming from a HPLC pump is transformed into a continuous stream

Christoph Janzen; Rüdiger Fleige; Reinhard Noll; Heinrich Schwenke; Wilhelm Lahmann; Joachim Knoth; Peter Beaven; Eckard Jantzen; Andreas Oest; Peter Koke

2005-01-01

358

Analysis of sucralose and other sweeteners in water and beverage samples by liquid chromatography\\/time-of-flight mass spectrometry  

Microsoft Academic Search

A methodology for the chromatographic separation and analysis of three of the most popular artificial sweeteners (aspartame, saccharin, and sucralose) in water and beverage samples was developed using liquid chromatography\\/time-of-flight mass spectrometry (LC\\/TOF-MS). The sweeteners were extracted from water samples using solid-phase extraction (SPE) cartridges. Furthermore, several beverages were analyzed by a rapid and simple method without SPE, and the

Imma Ferrer; E. Michael Thurman

2010-01-01

359

Evaluation of the lipophilicity of bile acids and their derivatives by thin-layer chromatography and principal component analysis  

Microsoft Academic Search

The lipophilic character of bile acids and their glyco- and tauro-conjugates was studied. The classical RMo values were measured by means of reversed thin-layer chromatography using a mixture of methanol–water as the solvent system and compared with the factors scores obtained by principal component analysis based also onto the TLC-retention data. The reliability of the factor scores values as lipophilic

Costel Sârbu; Ksenija Kuhajda; Slavko Kevresan

2001-01-01

360

Analysis of low molecular mass organic acids in natural waters by ion exclusion chromatography tandem mass spectrometry  

Microsoft Academic Search

A sensitive and selective method for the analysis of aliphatic low molecular mass organic acids (LMMOAs) in natural waters is presented. The method is based on separation with ion exclusion chromatography and detection with electrospray ionization tandem mass spectrometry (LC–MS\\/MS). The extra selectivity gained by applying MS\\/MS allows for a minimum of sample preparation and the use of a sub-optimal

Dan Bylund; Sara H. Norström; Sofia A. Essén; Ulla S. Lundström

2007-01-01

361

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

Microsoft Academic Search

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

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

1998-01-01

362

Thermal Degradation Behavior of Waste Video Cards Using Thermogravimetric Analysis and Pyrolysis Gas Chromatography\\/Mass Spectrometry Techniques  

Microsoft Academic Search

The thermal degradation characteristics of a printed circuit board assembly (PCBA), specifically video cards from waste computers, was studied using pyrolysis-gas chromatography-mass spectrometry (Py-GC\\/MS) and thermogravimetric analysis (TGA). The video-card waste was dismantled into substrate, integrated circuits (ICs), and plastic slots for comparable investigation. The results by TGA revealed that the initial temperature at which degradation began was 300 °C

Huabo Duan; Jinhui Li; Jyh-Feng Hwang; Wang Chen; Elisabeth Gilmore; Peter Adams; Lester Lave; Weifeng Jia; Violeta Mugica; Sara Hernandez; Miguel Torres; Rocio García; Antton Melendez; Estibaliz García; Pedro Carnicer; Egoitz Pena; Miren Larrion; Juan Legarreta; Cristina Gutierrez-Canas; Parikhit Sinha; William Schew; Aniket Sawant; Kyle Kolwaite; Sarah Strode; Stephanie Weber; Jill Engel-Cox; Raymond Hoff; Ana Prados; Hai Zhang; Valerie Garcia; Kristen Foley; Edith Gego; David Holland; S. Rao; Sundar Christopher; Pawan Gupta; Chengwen Wang; Yujue Wang; Yanqi Zhang; Qi Zhao; Ran Wang; Christian Murray; Frederick Lipfert; Jung-Nan Hsu; Hsunling Bai; Shou-Nan Li; Chuen-Jinn Tsai

2010-01-01

363

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

364

Analysis of free amino acids in natural waters by liquid chromatography-tandem mass spectrometry.  

PubMed

This paper reports a new analytical method for the analysis of 18 amino acids in natural waters using solid-phase extraction (SPE) followed by liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS) operated in multiple reaction monitoring mode. Two different preconcentration methods, solid-phase extraction and concentration under reduced pressure, were tested in development of this method. Although concentration under reduced pressure provided better recoveries and method limits of detection for amino acids in ultrapure water, SPE was a more suitable extraction method for real samples due to the lower matrix effects for this method. Even though the strong cation exchange resin used in SPE method introduced exogenous matrix interferences into the sample extracts (inorganic salt originating from the acid-base reaction during the elution step), the SPE method still incorporates a broad sample clean-up and minimised endogenous matrix effects by reducing interferences originating from real water samples. The method limits of quantification (MLQ) for the SPE LC-MS/MS method in ultrapure water ranged from 0.1 to 100 ?g L(-1) as N for the different amino acids. The MLQs of the early eluting amino acids were limited by the presence of matrix interfering species, such as inorganic salts in natural water samples. The SPE LC-MS/MS method was successfully applied to the analysis of amino acids in 3 different drinking water source waters: the average total free amino acid content in these waters was found to be 19 ?g L(-1) as N, while among the 18 amino acids analysed, the most abundant amino acids were found to be tyrosine, leucine and isoleucine. PMID:25454138

How, Zuo Tong; Busetti, Francesco; Linge, Kathryn L; Kristiana, Ina; Joll, Cynthia A; Charrois, Jeffrey W A

2014-11-28

365

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

366

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

PubMed Central

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

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

2009-01-01

367

Gas-liquid Flow Pattern Recognition Based on Wavelet Packet Energy Entropy of Vortex-induced Pressure Fluctuation  

NASA Astrophysics Data System (ADS)

Here we report a novel flow-pattern map to distinguish the gas-liquid flow patterns in horizontal pipes at ambient temperature and atmospheric pressure. The map is constructed using the coordinate system of wavelet packet energy entropy versus total mass flow rate. The wavelet packet energy entropy is obtained from the coefficients of vortex-induced pressure fluctuation decomposed by the wavelet packet transform. A triangular bluff body perpendicular to the flow direction is employed to generate the pressure fluctuation. Experimental tests confirm the suitability of the wavelet packet energy entropy as an ideal indicator of the gas-liquid flow patterns. The overall identification rate of the map is 92.86%, which can satisfy most engineering applications. This method provides a simple, practical, and robust solution to the problem of gas-liquid flow pattern recognition.

Sun, Zhiqiang; Shao, Shuai; Gong, Hui

2013-04-01

368

APPLICATIONS OF INFORMATION THEORY AND PATTERN RECOGNITION TO GAS CHROMATOGRAPHY-MASS SPECTROMETRIC ANALYSIS OF TOXIC ORGANIC COMPOUNDS IN AMBIENT AIR  

EPA Science Inventory

The number of information channels contained in the gas chromatographic, mass spectrometric, and combined gas chromatography-mass spectrometric analysis of 78 toxic organic compounds has been determined. The toxic compounds are those routinely monitored in ambient air samples usi...

369

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

370

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

371

Volatile compounds of rehydrated French beans, bell peppers and leeks. Part II. Gas chromatography\\/sniffing port analysis and sensory evaluation  

Microsoft Academic Search

The flavours of rehydrated diced French beans, red bell peppers and leeks were characterised by gas chromatography\\/sniffing port analysis (GC\\/SP) of volatile compounds released in a mouth model system, and by descriptive sensory analysis. Volatile compounds were identified by combined gas chromatography\\/mass spectrometry. In French beans, bell peppers and leeks, respectively, 10, 16 and 22 compounds possessed detectable odours. A

Saskia M. Van Ruth; Jacques P. Roozen; Jan L. Cozijnsen; Maarten A. Posthumus

1995-01-01

372

Adsorption of anionic nanosheets from their dilute colloidal suspensions onto gas-liquid interfaces with and without a Langmuir film of cationic surfactant.  

PubMed

The adsorption of [(Ca(2)Nb(3)O(10))(-)](n) (CNO) polyanionic nanosheets from their dilute colloidal suspensions onto gas-liquid interfaces with and without a cationic [N(CH(3))(2)(C(18)H(37))(2)](+) (DOA) surfactant film has been experimentally investigated. Our concern has been focused particularly on their dynamical aspects, which can be observed owing to the long specific time of the adsorption. The theoretical framework of the Langmuir adsorption model has enabled a quantitative analysis of the observed data, and that analysis has indicated that the presence of a positively charged Langmuir film enhances the ratio of the adsorption and desorption rate constants by approximately 30 times. Furthermore, the experimental results have shown that a "balanced" hybrid Langmuir film, in which both organic and inorganic constituents are densely packed, can be prepared. PMID:20141206

Ikegami, Keiichi; Tetsuka, Hiroyuki; Hoshi, Yasushi; Ebina, Takeo; Takashima, Hiroshi

2010-02-16

373

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

374

Multiresidue analysis of pesticides with hydrolyzable functionality in cooked vegetables by liquid chromatography tandem mass spectrometry.  

PubMed

It would be preferable for pesticide residues substituted by hydrolyzable functionality to be analyzed after cooking because their structures are apt to degrade during boiling and/or heating. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantitative determination of 44 pesticide residues with hydrolyzable functional group in five typical vegetable widely consumed in Republic of Korea is described. The sample clean-up was carried out according to the method of Food Code No. 83 established by the Korea Food and Drug Administration (KFDA). Zorbox XDB-C(18) column was selected for the analysis because of the best peak separation. The LC mobile phase consisted of water and 5 mm methanolic ammonium formate, which resulted in a peak shape with good symmetry at each run. Tandem mass spectroscopic (MS/MS) experiments were performed in ESI positive mode and the multiple reaction monitoring modes. A conventional matrix effect was modified to more comprehensive form 100gamma(ij) (%). A high matrix effect (<-30%) was detected for the seven polar pesticides, namely thiamethoxam, clothianidin, acetamiprid, aldicarb, thiacloprid, pirimicarb and methabenzthiazuron. The limits of detection were in the range of 0.1-8.1 microg/kg, indicating a good sensitivity. Most of the recoveries ranged from 70 to 131% with RSDs

Lee, Sung Joong; Park, Semin; Choi, Jin Young; Shim, Jae-Han; Shin, Eun-Ho; Choi, Jeong-Heui; Kim, Soo Taek; Abd El-Aty, A M; Jin, Jong Sung; Bae, Dong Won; Shin, Sung Chul

2009-07-01

375

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

376

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

SciTech Connect

Hydrocarbon-type fractions (saturates, aromatics, polynuclear aromatics, and polar compounds) from heavy crude oils and synthetic fuels were separated by thin layer chromatography (TLC) on chromarods, using an Iatroscan TH-10 analyzer. The best results were obtained on a silica gel chromarod when nhexane, 10 percent benzene in n-hexane, and 5 percent ethyl acetate in benzene were used as developing solvent. A complete analysis of six samples takes 60 min and requires only 60 mg of sample. Separation was applied to pure hydrocarbon mixtures as well as hydrocarbon-type concentrates isolated from Athabasca bitumen by liquid chromatography. The method is applicable to middle distillates, b.p. 200 to 350/sup 0/C, as well as to deasphaltened fractions (malthenes) boiling higher than 350/sup 0/C. Seven samples of malthenes (penthane-solubles) were analyzed by this method. Repeatability of the results was compared with that of the USBM-API procedure.

Poirier, M.A.; George, A.E.

1983-01-01

377

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

NASA Astrophysics Data System (ADS)

Recent advances in the coupling of gas chromatography (GC) and high performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometry (ICP MS) and their role in trace element speciation analysis of environmental materials are presented. The discussion is illustrated with three research examples concerning the following topics: (i) development and coupling of multicapillary microcolumn GC with ICP MS for speciation of organotin in sediment and biological tissue samples; (ii) speciation of arsenic in marine algae by size-exclusion-anion-exchange HPLC-ICP MS; and (iii) speciation of cadmium in plant cell cultures by size-exclusion HPLC-ICP MS. Particular attention is paid to the problem of signal identification in ICP MS chromatograms; the potential of electrospray MS/MS for this purpose is highlighted.

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

2000-07-01

378

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

379

Effect of impeller geometry on gas-liquid mass transfer coefficients in filamentous suspensions.  

PubMed

Volumetric gas-liquid mass transfer coefficients were measured in suspensions of cellulose fibers with concentrations ranging from 0 to 20 g/L. The mass transfer coefficients were measured using the dynamic method. Results are presented for three different combinations of impellers at a variety of gassing rates and agitation speeds. Rheological properties of the cellulose fibers were also measured using the impeller viscometer method. Tests were conducted in a 20 L stirred-tank fermentor and in 65 L tank with a height to diameter ratio of 3:1. Power consumption was measured in both vessels. At low agitation rates, two Rushton turbines gave 20% better performance than the Rushton and hydrofoil combination and 40% better performance than the Rushton and propeller combination for oxygen transfer. At higher agitation rates, the Rushton and hydrofoil combination gave 14 and 25% better performance for oxygen transfer than two Rushton turbines and the Rushton and hydrofoil combination, respectively. PMID:18576095

Dronawat, S N; Svihla, C K; Hanley, T R

1997-01-01

380

Foam formation and mitigation in a three-phase gas-liquid-particulate system.  

PubMed

Foaming is of great concern in a number of industrial processes involving three-phase gas-liquid-finely divided solid systems such as those encountered in the vitrification of highly radioactive nuclear waste slurries and sludges. Recent work has clearly shown that the surface properties of the particles such as hydrophilicity, hydrophobicity or biphilicity (i.e. partially wetted by water) are the cause of foamability and foam stability. The literature data on particles causing foaminess and foam stability in the absence of any surfactant are rather scarce. This paper presents experimental observations on aqueous foams with polyhedral structures containing over 90% air generated due to the presence of irregularly-shaped fine crystalline particles of sodium chloride which were modified into amphiphilic particles by physical adsorption of a cationic surfactant. Cross-polarized light microscopy was used to visualize the physical adsorption of the surfactant on the crystal surface. It is shown that these biphilic or amphiphilic particles attach to the air bubble surface and prevent the coalescence of bubbles, thereby extending the life of the foam. The foaming power of solid particles increases with an increase in the concentration of amphiphilic particles, and a maximum in foaminess is observed which is due to two competing effects. Amphiphilic particles promote foamability by attachment to the bubble surfaces as individual particles and foam inhibition due to the clustering or flocculation of particles in the bulk at high particle concentrations. We studied the adsorption of amphiphilic particles at a planar air-water surface and found that the degree of foamability correlates well with the particle coverage (i.e. adsorption density) at the air-liquid surface. An exploratory study was also conducted using an antifoam recently developed by IIT researchers to mitigate foaming in particle-laden gas-liquid systems. PMID:16997269

Vijayaraghavan, Krishna; Nikolov, Alex; Wasan, Darsh

2006-11-16

381

Determination of the 15N/14N ratio of ammonium and ammonia in aqueous solutions by equilibrium headspace-gas chromatography-combustion-isotope ratio mass spectrometry.  

PubMed

A method for determination of the 15N/14N ratio of total ammoniacal nitrogen (TAN; ammonium and ammonia) in aqueous solutions was developed, primarily intended for use with soil extracts, which have a high TAN level, e.g. from recently fertilised agricultural soils. Ammonium was converted to ammonia by addition of NaOH, followed by nitrogen isotopic analysis of the headspace by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) where complete separation of TAN from the matrix was not necessary. The ammonia concentration in the gas phase was maximised by increasing the temperature and salt concentration and by decreasing the gas liquid ratio in the headspace vials. Isotopic equilibrium was reached after less than 1 h at 80 degrees C. The measured isotopic ratio was constant for solutions containing 30-200 mM NH4-N, corresponding to 950-7000 ng NH3-N detected with the IRMS. The integrated area response at m/z 28 increased linearly with the ammonium ion concentration in the interval 10-200 mM NH4-N. The fractionation factor between the liquid and gas phases was 1.0054 +/- 0.0007 within the linear range, which is in agreement with values reported in the literature, but with a higher precision. Changes in temperature, gas:liquid ratio or salt concentration did not affect the measured ratio, demonstrating the robustness of the developed method. PMID:12146904

Norlin, Elin; Irgum, Knut; Anders Ohlsson, K E

2002-06-01

382

Qualitative and Quantitative Analysis of Lipid Classes in Fish Oils by Thin?Layer Chromatography with an Iatroscan Flame Ionization Detector (TLC?FID) and Liquid Chromatography with an Evaporative Light Scattering Detector (LC?ELSD)  

Microsoft Academic Search

Combined effects of hydrogen and air flow rates on the peak response of selected neutral lipid classes (triacylglycerol, diacylglycerol, monoacylglycerol, free fatty acids, and ethyl esters) were studied to optimize and calibrate the Iatroscan Mk?6s Chromarod system for the qualitative and quantitative analysis of lipid classes by thin?layer chromatography (TLC) with flame ionization detection in fish oil during the transesterification

W. M. Indrasena; K. Henneberry; C. J. Barrow; J. A. Kralovec

2005-01-01

383

Purification of dinosterol for hydrogen isotopic analysis using high-performance liquid chromatography–mass spectrometry  

Microsoft Academic Search

A semi-preparative normal-phase high-performance liquid chromatography–mass spectrometry (HPLC–MS) method is presented for the purification of various alcohol fractions from total lipid extracts derived from sediments, for the purpose of hydrogen isotopic measurement by gas chromatography–isotope ratio mass spectrometry (GC–IRMS). 4-Methylsterols, including the dinoflagellate-specific marker dinosterol (4,23,24-trimethylcholestan-22-en-3?-ol), were successfully separated from notoriously co-eluting plant-derived pentacyclic triterpenoid alcohols and alkyl alcohols. We

Rienk H. Smittenberg; Julian P. Sachs

2007-01-01

384

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

385

Estimation of the uncertainty associated with the results based on the validation of chromatographic analysis procedures: application to the determination of chlorides by high performance liquid chromatography and of fatty acids by high resolution gas chromatography.  

PubMed

This article presents a model to calculate the uncertainty associated with an analytical result based on the validation of the analysis procedure. This calculation model is proposed as an alternative to commonly used bottom-up and top-down methods. This proposal is very advantageous as the validation of the procedures and the estimation of the uncertainty of the measurement are part of the technical requirements needed in order to obtain the ISO 17025:2005 accreditation. This model has been applied to the determination of chloride by liquid chromatography in lixiviates and in the determination of palmitic acid and stearic acid by gas chromatography in magnesium stearate samples. PMID:22227361

Quintela, M; Báguena, J; Gotor, G; Blanco, M J; Broto, F

2012-02-01

386

Trace analysis of organic compounds by high-performance liquid chromatography with photoionization detection.  

PubMed

Photoionization detection (PID) has now been successfully interfaced with modern high-performance liquid chromatography (HPLC) to provide a new "hyphenated" technique, HPLC-PID. This method is compatible with reversed-phase HPLC solvents and conditions, as well as with certain organic solvents used in normal-phase liquid chromatography. The HPLC-PID interface consists of a variable-ratio eluent splitter, operated inside a heated oven, which vaporizes both analytes and mobile phase prior to introduction into the detector. Depending on the energy (eV) of the photoionization detector lamp, most of the solvents commonly used in reversed-phase liquid chromatography are compatible with long-term, on-line, real-time, continuous photoionization detector operation. Virtually all organic classes now detectable by gas chromatography-PID can also be detected by HPLC-PID, but with somewhat poorer detection limits. In certain instances, minimum detection limits are in the 5-500 ng/injection range. The HPLC-PID system appears ideal for aromatic or aliphatic amines, substituted hydrocarbons, and certain other classes of organic compounds. Various applications of HPLC-PID, under reversed-phase conditions are illustrated and discussed. PMID:6501505

Driscoll, J N; Conron, D W; Ferioli, P; Krull, I S; Xie, K H

1984-10-19

387

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...

388

(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...

389

SURVEY ANALYSIS OF PHENOLIC COMPOUNDS IN INDUSTRIAL EFFLUENTS BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY  

EPA Science Inventory

Analyzing industrial effluents for phenolic compounds involves a number of problems both in the separation of these compounds from the aqueous medium and in the chromatography of the extracted compounds. Use of continuous liquid-liquid extractor improved the recovery of phenolic ...

390

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...

391

ANALYSIS OF TRIGLYCERIDES AND RELATED COMPOUNDS IN FOOD USING LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY TECHNIQUES  

Technology Transfer Automated Retrieval System (TEKTRAN)

The most common ionization sources available today to couple liquid chromatography (LC) with mass spectrometry (MS) are atmospheric pressure ionization (API) sources that form ions at ambient pressure and sample them into the high vacuum region of the mass analyzer. The two most popular API sources...

392

Optimization of Analysis Method of Kudzu Root Crude Extract by High Performance Liquid Chromatography  

Microsoft Academic Search

Kudzu root is an important traditional Chinese herb. Its crude extract has been used in the treatment of hypertension and angina pectoris in China. Several parameters for high performance liquid chromatography (HPLC) analytical method for kudzu root extract, including HPLC model, mobile phase, additive and gradient conditions, have been optimized. The HPLC retention parameters a and c, and the peak

Yan ZHANG; Xingya XUE; Qing XU; Feifang ZHANG; Xinmiao LIANG

2006-01-01

393

Analysis of Peppermint Leaf and Spearmint Leaf Extracts by Thin-Layer Chromatography  

ERIC Educational Resources Information Center

In this inquiry-based activity, the usefulness of thin-layer chromatography (TLC) to visualize the difference between spearmint and peppermint is explored. The experiment may be used in any class where TLC is discussed from high school to college. We have used this activity with science majors in an organic chemistry laboratory, with non-science…

Pelter, Libbie S. W.; Amico, Andrea; Gordon, Natalie; Martin, Chylah; Sandifer, Dessalyn; Pelter, Michael W.

2008-01-01

394

Current trends in green liquid chromatography for the analysis of pharmaceutically active compounds in the environmental water compartments.  

PubMed

Green analytical chemistry is an aspect of green chemistry which introduced in the late nineties. The main objectives of green analytical chemistry are to obtain new analytical technologies or to modify an old method to incorporate procedures that use less hazardous chemicals. There are several approaches to achieve this goal such as using environmentally benign solvents and reagents, reducing the chromatographic separation times and miniaturization of analytical devices. Traditional methods used for the analysis of pharmaceutically active compounds require large volumes of organic solvents and generate large amounts of waste. Most of them are volatile and harmful to the environment. With the awareness about the environment, the development of green technologies has been receiving increasing attention aiming at eliminating or reducing the amount of organic solvents consumed everyday worldwide without loss in chromatographic performance. This review provides the state of the art of green analytical methodologies for environmental analysis of pharmaceutically active compounds in the aquatic environment with special emphasis on strategies for greening liquid chromatography (LC). The current trends of fast LC applied to environmental analysis, including elevated mobile phase temperature, as well as different column technologies such as monolithic columns, fully porous sub-2?m and superficially porous particles are presented. In addition, green aspects of gas chromatography (GC) and supercritical fluid chromatography (SFC) will be discussed. We pay special attention to new green approaches such as automation, miniaturization, direct analysis and the possibility of locating the chromatograph on-line or at-line as a step forward in reducing the environmental impact of chromatographic analyses. PMID:25476373

Shaaban, Heba; Górecki, Tadeusz

2015-01-15

395

Foundations of retention in partition chromatography.  

PubMed

The connection between the observable output in column chromatography (retention time, retention volume, retention factor, separation factor, etc.) and system properties (hold-up volume, pressure, temperature, isotherm behavior, etc.) is discussed from a practical and mechanistic perspective for gas-liquid chromatography, reversed-phase liquid chromatography, supercritical fluid chromatography, micellar electrokinetic chromatography, and capillary electrochromatography. The unifying feature of these techniques is that retention can be described by a partition model, although not always exclusively. When over simplistic system models are used to explain variation in retention parameters they frequently mask the true reasons for poor repeatability and difficulties in transfer between system. Methods employing relative retention afford higher precision but may contain residual uncorrected errors. For those systems with several separate mechanisms contributing to retention the effective retention parameters can no longer be interpreted by simple partition models. The broadly based and practically focused material in this article affords an illustration of the often complicated relationship between system properties and retention, and the dangers that lurk in simplified retention models if the validity of their underlining approximations is not appropriate for the system under study. PMID:19013576

Poole, Colin F; Poole, Salwa K

2009-03-01

396

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

397

Analysis of selective androgen receptor modulators by gas chromatography-microchip atmospheric pressure photoionization-mass spectrometry.  

PubMed

A gas chromatography-microchip atmospheric pressure photoionization-mass spectrometric (GC-microAPPI-MS) method was developed and used for the analysis of three 2-quinolinone-derived selective androgen receptor modulators (SARMs). SARMs were analyzed from spiked urine samples, which were hydrolyzed and derivatized with N-methyl-N-(trimethylsilyl)trifluoroacetamide before analysis. Trimethylsilyl derivatives of SARMs formed both radical cations (M(+*)) and protonated molecules ([M + H](+)) in photoionization. Better signal-to-noise ratios (S/N) were obtained in MS/MS analysis using the M(+*) ions as precursor ions than using the [M + H](+) ions, and therefore the M(+*) ions were selected for the precursor ions in selected reaction monitoring (SRM) analysis. Limits of detection (LODs) with the method ranged from 0.01 to 1 ng/mL, which correspond to instrumental LODs of 0.2-20 pg. Limits of quantitation ranged from 0.03 to 3 ng/mL. The mass spectrometric response to the analytes was linear (R > or = 0.995) from the LOQ concentration level up to 100 ng/mL concentration, and intra-day repeatabilities were 5%-9%. In addition to the GC-microAPPI-MS study, the proof-of-principle of gas chromatography-microchip atmospheric pressure chemical ionization-Orbitrap MS (GC-microAPCI-Orbitrap MS) was demonstrated. PMID:20004589

Luosujärvi, Laura; Haapala, Markus; Thevis, Mario; Saarela, Ville; Franssila, Sami; Ketola, Raimo A; Kostiainen, Risto; Kotiaho, Tapio

2010-02-01

398

Direct numerical simulation of the near-field dynamics of annular gas-liquid two-phase jets  

NASA Astrophysics Data System (ADS)

Direct numerical simulation has been used to examine the near-field dynamics of annular gas-liquid two-phase jets. Based on an Eulerian approach with mixed fluid treatment, combined with an adapted volume of fluid method and a continuum surface force model, a mathematical formulation for the flow system is presented. The swirl introduced at the jet nozzle exit is based on analytical inflow conditions. Highly accurate numerical methods have been utilized for the solution of the compressible, unsteady, Navier-Stokes equations. Two computational cases of gas-liquid two-phase jets including swirling and nonswirling cases have been performed to investigate the effects of swirl on the flow field. In both cases the flow is more vortical at the downstream locations. The swirling motion enhances both the flow instability resulting in a larger liquid spatial dispersion and the mixing resulting in a more homogeneous flow field with more evenly distributed vorticity at the downstream locations. In the annular nonswirling case, a geometrical recirculation zone adjacent to the jet nozzle exit was observed. It was identified that the swirling motion is responsible for the development of a central recirculation zone, and the geometrical recirculation zone can be overwhelmed by the central recirculation zone leading to the presence of the central recirculation region only in the swirling gas-liquid case. Results from a swirling gas jet simulation were also included to examine the effect of the liquid sheet on the flow physics. The swirling gas jet developed a central recirculation region, but it did not develop a precessing vortex core as the swirling gas-liquid two-phase jet. The results indicate that a precessing vortex core can exist at relatively low swirl numbers in the gas-liquid two-phase flow. It was established that the liquid greatly affects the precession and the swirl number alone is an insufficient criterion for the development of a precessing vortex core.

Siamas, George A.; Jiang, Xi; Wrobel, Luiz C.

2009-04-01

399

Multiresidue analysis of pollutants as their trimethylsilyl derivatives, by gas chromatography-mass spectrometry.  

PubMed

This paper reports a multiresidue analysis procedure which permits the identification and quantification of sixty-three water-soluble pollutants. Subsequent to their solid-phase extraction (SPE) enrichment, analyses of species have been carried out from one solution, by a single injection, as their trimethylsilyl-oxime ether/ester derivatives, by gas chromatography-mass spectrometry, within 31min. Based on our optimized extraction, derivatization and mass fragmentation studies separation have been performed in the total ion current mode, identification and quantification of compounds have been carried out on the basis of their selective fragment ions. Including various pharmaceuticals, benzoic acid, its substituted species, different aromatic carboxylic acids, cholic acids, unsaturated and saturated fatty acids, aliphatic dicarboxylic acids, as well as synthetic pollutants of various origins (2,4-di-tert-butylphenol, different phthalates). Standard compounds were added to 500 mL effluent wastewater samples, at three concentrations (1-5 microg/L, 5-10 microg/L and 10-20 microg/L). Recoveries, using the Waters Oasis cartridges performing extractions at pH 2, pH 4 and pH 7 proved to be the optimum at pH 4 (average recoveries (94.5%), except for cholesterol (10%), paracetamol (18%) and 2,5-dihydroxybenzoic acid (25%). Carbamazepine could be recovered at pH 7, only. Responses, obtained with derivatized standards proved to be linear in the range of 4-80 microg/L levels. Limit of quantitation values varied between 0.92 ng/L (4-hydroxyphenylacetic acid) and 600 ng/L (dehydrocholic acid) concentrations. One of the most important messages of this work is the confirmation of the origin of blank values. It was shown that contaminants, mainly 2,4-di-tert-butylphenol, different phthalates and fatty acids, are sourced both from the reagents and mainly from the SPE procedure, independent on the cartridge applied. Reproducibilities, characterized with the relative standard deviations (RSDs) of measurements, varied between 0.71% and 10%, with an average of 4.38% RSD. The practical utility of the method was shown by the identification and quantification of the pollutant contents of Hungarian influent and effluent wastewaters (for six consecutive months and that of the Danube River for 2 months). PMID:19201001

Sebok, A; Vasanits-Zsigrai, A; Helenkár, A; Záray, Gy; Molnár-Perl, I

2009-03-20

400

Analysis of chemical profiles of insect adhesion secretions by gas chromatography-mass spectrometry.  

PubMed

This article reports on the chemical analysis of molecular profiles of tarsal secretions of the desert locust Schistocerca gregaria (Forsskål, 1775) by gas chromatography hyphenated with quadrupol mass spectrometry (GC-MS) as well as (1)H-nuclear magnetic resonance ((1)H NMR) spectroscopy. Special focus of this study was to elaborate on sampling methods which enable selective microscale extraction of insect secretions in a spatially controlled manner, in particular tarsal adhesive secretions and secretions located on cuticle surfaces at the tibia. Various solvent sampling procedures and contact solid-phase microextraction (SPME) methods were compared in terms of comprehensiveness and extraction efficiencies as measured by signal intensities in GC-MS. Solvent sampling with water as extraction solvent gave access to the elucidation of chemical profiles of polar compound classes such as amino acids and carbohydrates, but is extremely tedious. Contact SPME on the other hand can be regarded as a simplified and more elegant alternative, in particular for the lipophilic compound fraction. Many proteinogenic amino acids and ornithine as well as carbohydrate monomers arabinose, xylose, glucose, and galactose were detected in tarsal secretions after acid hydrolysis of aqueous extracts. Qualitatively similar but quantitatively significantly different molecular profiles were found for the lipid fraction which contained mainly n-alkanes and internally branched monomethyl-, dimethyl-, and trimethyl-alkanes in the C23-C49 range as well as long chain fatty acids and aldehydes. Especially, hydrocarbons with >C40 carbon numbers have previously been rarely reported for insect secretions. The results suggest that the investigated insect secretions are complex emulsions which allow the attachment of tarsi on various otherwise incompatible materials of smooth and rough surfaces. The solid consistence of the established alkanes at ambient temperatures might contribute to a semi-solid consistence of the adhesive, amalgamating partly opposing functions such as slip resistance, tarsal release, desiccation resistance, and mechanical compliance. The methods developed can be extended to other similar applications of studying compositions of insect secretions of other species. PMID:25479867

Reitz, Manuela; Gerhardt, Heike; Schmitt, Christian; Betz, Oliver; Albert, Klaus; Lämmerhofer, Michael

2015-01-01

401

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.

402

Off-line two-dimensional liquid chromatography with maximized sample loading to reversed-phase liquid chromatography-electrospray ionization tandem mass spectrometry for shotgun proteome analysis.  

PubMed

We demonstrate a strategy of maximizing the performance of reversed-phase (RP) liquid chromatography (LC) tandem mass spectrometry (MS/MS) for efficient shotgun proteome analysis by optimizing the sample loading to the instrument in an off-line two-dimensional (2D) LC tandem MS platform. To determine the quantity of peptides present in a proteome digest or fractionated peptides from strong-cation exchange (SCX) separation, an automated system based on RPLC with a rapid step solvent gradient for peptide elution and ultraviolet (UV) detection was developed. This system also allowed the purification of the peptides by removing salts and other impurities present in a sample. It was found that controlling the amount of peptides injected into a RPLC MS/MS system was critical to achieve the maximum efficiency in peptide and protein identification. With the use of off-line 2D-LC-MS/MS, peptide fractions from the first dimension of separation were desalted and quantified, followed by injecting the optimal amount of the sample into RPLC-MS/MS for peptide sequencing. The application of this strategy was demonstrated in the proteome profiling of breast cancer MCF-7 cells. From the analysis of 28 SCX fractions with each injecting 1 microg of sample into a 75 mum x 100 mm C18 column interfaced to a quadrupole/time-of-flight mass spectrometer, a total of 2362 unique proteins or protein groups were identified with a false positive peptide identification rate of 0.19%, as determined by target-decoy proteome sequence searches. Replicate 2 h runs of individual fractions with the exclusion of precursor ions of peptides already identified in the first runs resulted in the identification of an additional 549 unique proteins or protein groups with a false positive identification rate of 0.60%. This example illustrated that off-line 2D-LC-MS/MS, with maximal sample injection to the RPLC-MS, is an effective method for shotgun proteome analysis. Finally, the advantages and limitations of this method, compared to other methods, are discussed. PMID:19178338

Wang, Nan; Xie, Chuanhui; Young, J Bryce; Li, Liang

2009-02-01

403

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

SciTech Connect

This work describes a rapid method for hydrocargon-type analysis applying thin layer chromatography (TLC) to the pentane-soluble fraction *malthenes) of the petroleum and synthetic fuels boiling above 200/sup 0/C. The principal component types encountered in this paper are saturates (SA), aromatics (AR), (mono and di together) polynuclear aromatics (PNA) and polar material (PO). The method uses a Iatroscan TLC pyrolyzer which combines the resolution capabilities of TLC with the possibility of quantification by using a flame-ionization detector (FID). Comparison of the results with those obtained by the API-60 procedure is presented.

Poirier, M.A.; George, A.E.

1982-09-01

404

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

405

Flow Chemistry: Intelligent Processing of Gas-Liquid Transformations Using a Tube-in-Tube Reactor.  

PubMed

Conspectus The previous decade has witnessed the expeditious uptake of flow chemistry techniques in modern synthesis laboratories, and flow-based chemistry is poised to significantly impact our approach to chemical preparation. The advantages of moving from classical batch synthesis to flow mode, in order to address the limitations of traditional approaches, particularly within the context of organic synthesis are now well established. Flow chemistry methodology has led to measurable improvements in safety and reduced energy consumption and has enabled the expansion of available reaction conditions. Contributions from our own laboratories have focused on the establishment of flow chemistry methods to address challenges associated with the assembly of complex targets through the development of multistep methods employing supported reagents and in-line monitoring of reaction intermediates to ensure the delivery of high quality target compounds. Recently, flow chemistry approaches have addressed the challenges associated with reactions utilizing reactive gases in classical batch synthesis. The small volumes of microreactors ameliorate the hazards of high-pressure gas reactions and enable improved mixing with the liquid phase. Established strategies for gas-liquid reactions in flow have relied on plug-flow (or segmented flow) regimes in which the gas plugs are introduced to a liquid stream and dissolution of gas relies on interfacial contact of the gas bubble with the liquid phase. This approach confers limited control over gas concentration within the liquid phase and is unsuitable for multistep methods requiring heterogeneous catalysis or solid supported reagents. We have identified the use of a gas-permeable fluoropolymer, Teflon AF-2400, as a simple method of achieving efficient gas-liquid contact to afford homogeneous solutions of reactive gases in flow. The membrane permits the transport of a wide range of gases with significant control of the stoichiometry of reactive gas in a given reaction mixture. We have developed a tube-in-tube reactor device consisting of a pair of concentric capillaries in which pressurized gas permeates through an inner Teflon AF-2400 tube and reacts with dissolved substrate within a liquid phase that flows within a second gas impermeable tube. This Account examines our efforts toward the development of a simple, unified methodology for the processing of gaseous reagents in flow by way of development of a tube-in-tube reactor device and applications to key C-C, C-N, and C-O bond forming and hydrogenation reactions. We further describe the application to multistep reactions using solid-supported reagents and extend the technology to processes utilizing multiple gas reagents. A key feature of our work is the development of computer-aided imaging techniques to allow automated in-line monitoring of gas concentration and stoichiometry in real time. We anticipate that this Account will illustrate the convenience and benefits of membrane tube-in-tube reactor technology to improve and concomitantly broaden the scope of gas/liquid/solid reactions in organic synthesis. PMID:25611216

Brzozowski, Martin; O'Brien, Matthew; Ley, Steven V; Polyzos, Anastasios

2015-02-17

406

Drop tower experiment for performance evaluation of gas-liquid equilibrium thruster for small spacecraft  

NASA Astrophysics Data System (ADS)

JAXA/ISAS is developing the gas-liquid equilibrium thruster for a small spacecraft. In small spacecrafts, the thruster system must be simple and its weight must be light. This thruster system uses HFC-134a (1,1,1,2-tetrafluoroethane) , a kind of liquefied gas, as propellant because of its harmlessness and ease of handling. And this thruster stores propellant as liquid in the tank and ejects propellant as gas using the gas-liquid equilibrium pressure to produce thrust, so the propellant tank only needs to resist the vapor pressure of propellant. In this thruster system, the porous metal is also equipped in the tank for the following performance advantages: (1) liquid fuel retention: The porous metal reduces sloshing problems which cause bad effects on spacecraft attitude by retaining liquid propellant inside the porous metal: (2) vapor-liquid separation: The porous metal also helps propellant separate gas from liquid by advancing propellant vaporization on its large surface area and retaining liquid propellant using its surface tension. In last autumn, we carried out the experiment to evaluate these two advantages of porous metal under micro gravity condition using 50 meters drop tower in Hokkaido, Japan. The system of this experiment divides into two different systems. The first one evaluates liquid propellant retention performance by adding disturbance to liquid propellant absorbed in porous metal. The disturbance is centrifugal force and angular acceleration worked on the liquid propellant by rotating propellant tank controlled by motor. A high speed camera records the behavior of the liquid propellant. The other one evaluates the ability of gas-liquid separation on the case of propellant ejection. In this evaluation, the parameters are full filling porous metal or some ullage in the tank, nozzle diameters and the filling ratio of liquid propellant in the tank. As for (1) liquid fuel retention, in all conducted cases without propellant ejection, liquid propellant was retained in the porous metal. It is obvious that the porous metal is effective for decreasing of sloshing problems. We evaluated this effectiveness analytically based on head pressure worked on liquid propellant as centrifugal force and angular acceleration. As for (2)vapor-liquid separation, liquid propellant retained inside the porous metal started to boil right after propellant ejection occurred and propellant was ejected mixed with liquid. And after propellant ejection, it takes some time to recover tank pressure into saturated vapor pressure. To obtain stable thrust force, it is required to halt the propellant ejection just before the tank pressure reaches to the break point pressure and to take enough ejection intervals to recover the tank pressure. From these experiments, for practical use of this thruster system, that is, to avoid liquid propellant ejection, it is important to ensure adequate ullage volume of tank to achieve mission requirement.

Motooka, Norizumi; Yamamoto, Takayuki; Mori, Osamu; Okano, Yoshinobu; Kishino, Yoshihiro; Kawaguchi, Junichiro

407

Trace mycotoxin analysis in complex biological and food matrices by liquid chromatography-atmospheric pressure ionisation mass spectrometry.  

PubMed

Mycotoxins are toxic secondary metabolites produced by filamentous fungi that are growing on agricultural commodities. Their frequent presence in food and their severe toxic, carcinogenic and estrogenic properties have been recognised as potential threat to human health. A reliable risk assessment of mycotoxin contamination for humans and animals relies basically on their unambiguous identification and accurate quantification in food and feedstuff. While most screening methods for mycotoxins are based on immunoassays, unambiguous analyte confirmation can be easily achieved with mass spectrometric methods, like gas chromatography/mass spectrometry (GC/MS) or liquid chromatography/mass spectrometry (LC/MS). Due to the introduction of atmospheric pressure ionisation (API) techniques in the late 80s, LC/MS has become a routine technique also in food analysis, overcoming the traditional drawbacks of GC/MS regarding volatility and thermal stability. During the last few years, this technical and instrumental progress had also an increasing impact on the expanding field of mycotoxin analysis. The aim of the present review is to give an overview on the application of LC-(API)MS in the analysis of frequently occurring and highly toxic mycotoxins, such as trichothecenes, ochratoxins, zearalenone, fumonisins, aflatoxins, enniatins, moniliformin and several other mycotoxins. This includes also the investigation of some of their metabolites and degradation products. Suitable sample pre-treatment procedures, their applicability for high sample through-put and their influence on matrix effects will be discussed. The review covers literature published until July 2006. PMID:17087969

Zöllner, Peter; Mayer-Helm, Bernhard

2006-12-15

408

Quantitative statistical analysis of standard and human blood proteins from liquid chromatography, electrospray ionization, and tandem mass spectrometry.  

PubMed

It will be important to determine if the parent and fragment ion intensity results of liquid chromatography, electrospray ionization and tandem mass spectrometry (LC-ESI-MS/MS) experiments have been randomly and independently sampled from a normal population for the purpose of statistical analysis by general linear models and ANOVA. The tryptic parent peptide and fragment ion m/z and intensity data in the mascot generic files from LC-ESI-MS/MS of purified standard proteins, and human blood protein fractionated by partition chromatography, were parsed into a Structured Query Language (SQL) database and were matched with protein and peptide sequences provided by the X!TANDEM algorithm. The many parent and/or fragment ion intensity values were log transformed, tested for normality, and analyzed using the generic Statistical Analysis System (SAS). Transformation of both parent and fragment intensity values by logarithmic functions yielded intensity distributions that closely approximate the log-normal distribution. ANOVA models of the transformed parent and fragment intensity values showed significant effects of treatments, proteins, and peptides, as well as parent versus fragment ion types, with a low probability of false positive results. Transformed parent and fragment intensity values were compared over all sample treatments, proteins or peptides by the Tukey-Kramer Honestly Significant Difference (HSD) test. The approach provided a complete and quantitative statistical analysis of LC-ESI-MS/MS data from human blood. PMID:22316523

Bowden, Peter; Thavarajah, Thanusi; Zhu, Peihong; McDonell, Mike; Thiele, Herbert; Marshall, John G

2012-04-01

409

Comparison of different amino acid derivatives and analysis of rat brain microdialysates by liquid chromatography tandem mass spectrometry.  

PubMed

The efficiencies of three derivatisation reagents that react with either the amine (9-fluorenylmethyl chloroformate (FMOC)) or the carboxylic acid group (butanol) of amino acid or with both types of functional groups (propyl chloroformate) were compared in the analysis of amino acids by liquid chromatography-electrospray-tandem mass spectrometry (LC-ESI-MS/MS). Separation of 20 amino acids derivatised with these three reagents was studied on reversed-phase chromatography. Linearity, repeatability and limits of detection of the LC-ESI-MS/MS method were determined by analysing FMOC-, butanol- and propyl chloroformate-derivatised lysine, beta-aminobutyric acid, threonine and glutamic acid. The limits of detection for the derivatised amino acids (7.5-75fmol) were as much as 2-60 times lower than those of the corresponding underivatised molecules. The best linearity was observed for amino acids derivatised with propyl chloroformate or butanol (r(2)=0.996-0.999, range=100-8500nmolL(-1)). Propyl chloroformate was the best suited of the reagents tested for the analysis of amino acids with LC-MS/MS and was used for the analysis of amino acids in rat brain microdialysis samples. PMID:19166726

Uutela, Päivi; Ketola, Raimo A; Piepponen, Petteri; Kostiainen, Risto

2009-02-01

410

[Analysis of C4 fluoride compounds in alkylation materials by gas chromatography/flame ionization detection (GC/FID)].  

PubMed

A method for the analysis of C4 fluoride compounds in alkylation materials was developed by GC/FID. In order to confirm the presence of C4 fluoride compounds in alkylation materials, 1-fluorobutane, 2-fluorobutane and 2-fluoro-2-methylpropane were synthesized and analysed by GC/FID, gas chromatography/atomic emission detection (GC/AED) and gas chromatography/mass spectrometry (GC/MS). The results showed that only 2-fluoro-2-methylpropane existed in the alkylation materials. Based on the properties of element response on GC/AED, the calibration factors of C4 fluoride compounds on GC/FID were calculated. The analysis was performed on OV-225 (50 m x 0.25 mm i. d. x 0.25 microm) and SE-54 (44 m x 0.22 mm i. d. x 0.25 microm) columns, which were connected in series. FID was used as the detector. In quantitative analysis of the alkylation materials the methods of calibration normalization and indirect external standard were suggested. The calibration curves were linear (r = 0.992) in the concentration range of 156 - 700 microL/L. The minimum detection limit of 2-fluoro-2-methylpropane in real samples was 150 microL/L (S/N = 3). The method is simple, reproducible and easy to be applied. The other components in the alkylation materials can also be analyzed if the calibration normalization method is used. PMID:15706940

Han, Jianghua; Yang, Haiying

2004-09-01

411

Isolation of naturally occurring aluminium ligands using immobilized metal affinity chromatography for analysis by ESI-MS.  

PubMed

Aluminium (iii) is one of the most abundant metal ions found in soil. Typically, Al(+3) is bound to minerals, but its bioavailability and toxicity toward vascular plants increases with increasing soil acidity. Ectomycorrhizal fungi, which live symbiotically on the roots of numerous woody plants, often confer Al(+3) resistance to host plants by reducing metal availability to the plant by unknown mechanisms. A potential mechanism of detoxification is binding of the Al(+3) by organic compounds that are exuded by the fungi into the surrounding soil and solution. A novel method has been developed to purify and characterize Al(+3) binding ligands from Pisolithus tinctorius exudate solutions using Al(+3) immobilized metal affinity chromatography (IMAC), reversed phase chromatography, and mass spectrometry. Fungal exudates produced by P. tinctorius exhibit a strong binding capacity for Al(+3), allowing their selective enrichment and collection using this IMAC method. Elution of the ligands requires the use of high pH. RP-HPLC separation and elemental analysis of the IMAC elutent indicates that the Al(+3) and the exudate ligands both elute from the column but are not bound in a complex. Thus, reversed phase HPLC at pH 10 is used for separation of the ligands and Al(+3) prior to MS analysis. The strongest binding IMAC fraction is analyzed by electrospray ionization mass spectrometry in positive and negative ion modes. This report provides new methods for the direct purification and analysis of naturally occurring ligands that bind hard metal ions. PMID:15724160

Baldwin, Carson; Cumming, Jonathan; Timperman, Aaron T

2005-03-01

412

Thin-layer chromatography and colorimetric analysis of multi-component explosive mixtures  

DOEpatents

A thin-layer chromatography method for detection and identification of common military and peroxide explosives in samples includes the steps of provide a reverse-phase thin-layer chromatography plate; prepare the plate by marking spots on which to deposit the samples by touching the plate with a marker; spot one micro liter of a first standard onto one of the spots, spot one micro liter of a second standard onto another of the spots, and spot samples onto other of spots producing a spotted plate; add eluent to a developing chamber; add the spotted plate to the developing chamber; remove the spotted plate from the developing chamber producing a developed plate; place the developed plate in an ultraviolet light box; add a visualization agent to a dip tank; dip the developed plate in the dip tank and remove the developed plate quickly; and detect explosives by viewing said developed plate.

Pagoria, Philip F.; Mitchell, Alexander R.; Whipple, Richard E.; Carman, M. Leslie

2014-08-26

413

Analysis of lipids from cooked beef by thin-layer chromatography with flame-ionization detection  

Microsoft Academic Search

Lipids were extracted from cooked ground beef with methylene chloride\\/methanol (2:1). The lipids were separated on a silicic\\u000a acid column, into neutral and polar fractions by elution with methylene chloride, followed by methanol. These fractions were\\u000a analyzed by Iatroscan thin-layer chromatography with flame-ionization detection instrumentation on Chromarods S-III (silica\\u000a gelcoated quartz rods). Comparison of cooked beef stored for 0, 4

Allen J. St. Angelo; Charles James

1993-01-01

414

Triglyceride analysis by gas chromatography in assessment of authenticity of goat milk fat  

Microsoft Academic Search

The triglyceride (TG) composition of 35 samples of milk collected at different times of year from five herds of goats was\\u000a analyzed using short capillary column-gas chromatography. The distribution of TG in goat milk fat was unimodal, peaking at\\u000a C40 (12.6%); the sum of TG from C38 to C44 accounted for about 50%, whereas the three classes of TG from

J. Fontecha; V. Díaz; M. J. Fraga; M. Juárez

1998-01-01

415

The quantitative analysis of triglyceride mixtures by thin layer chromatography on silica impregnated with silver nitrate  

Microsoft Academic Search

The paper describes a procedure involving thin layer chromatography on silica impregnated with silver nitrate, which makes\\u000a possible the separation of synthetic and natural glyceride mixtures into classes according to their degree of unsaturation,\\u000a and within those classes the resolution of certain isomeric unsaturated glycerides. The separations depend upon the ability\\u000a of compounds having an olefinic double bond to form

C. B. Barrett; M. S. J. Dallas; F. B. Padley

1963-01-01

416

Counter-current chromatography based analysis of synergy in an anti-tuberculosis ethnobotanical  

Microsoft Academic Search

The crude extract of an Alaskan ethnobotanical plant, Oplopanax horridus, was subjected to counter-current chromatography (CCC), and the selected active regions were evaluated for their synergistic effects with an in vitro model of anti-tubercular efficacy. CCC as a support-free high-resolution separation method was employed to preclude potential irreversible absorption to a solid stationary phase. The microplate Alamar blue assay and

Taichi Inui; Yuehong Wang; Shixin Deng; David C. Smith; Scott G. Franzblau; Guido F. Pauli

2007-01-01

417

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

418

Multiresidue pesticide analysis of fruits by ultra-performance liquid chromatography tandem mass spectrometry  

Microsoft Academic Search

Ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC–MS–MS) has been used for screening and quantification\\u000a of 32 pesticides and metabolites in two fruit matrices. The compounds investigated belonged to different chemical families\\u000a of insecticides, acaricides, fungicides, and herbicides; several metabolites were also included. Quantification was conducted\\u000a using matrix-matched standards calibration; response was a linear function of concentration in the

O. J. Pozo; M. Barreda; J. V. Sancho; F. Hernández; J. Ll. Lliberia; M. A. Cortés; B. Bagó

2007-01-01

419

Signal analysis of NEMS sensors at the output of a chromatography column  

NASA Astrophysics Data System (ADS)

This article introduces a joined Bayesian estimation of gas samples issued from a gas chromatography column (GC) coupled with a NEMS sensor based on Giddings Eyring microscopic molecular stochastic model. The posterior distribution is sampled using a Monte Carlo Markov Chain and Gibbs sampling. Parameters are estimated using the posterior mean. This estimation scheme is finally applied on simulated and real datasets using this molecular stochastic forward model.

Bertholon, François; Harant, Olivier; Jutten, Christian; Bourlon, Bertrand; Gerfault, Laurent; Grangeat, Pierre

2015-01-01

420

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

421

Studies of Wavy Films in Vertical Gas-Liquid Annular Flows  

NASA Astrophysics Data System (ADS)

Annular gas-liquid flow is encountered in many industrial applications such as wetted-wall absorbers, falling-film reactors, condensers and evaporators and transport of oil and gas mixtures from offshore pipelines. Experimental observations show that the presence of waves on the liquid film increases the transport rates of momentum, heat and mass by 100 to 300% over those expected from the flat film. Previous modeling efforts to predict this transport enhancement have largely been unsuccessful as they were limited to very low Reynolds numbers. This work presents a new model for describing the evolution of large amplitude waves on laminar falling wavy films at high Reynolds numbers (Re > 100). The model is based on second-order boundary layer theory and includes the pressure variation across the film as well as higher order viscous terms. The consistency and accuracy of the model is verified by comparing the linear stability results with the classical Kapitza's boundary layer model and Orr-Sommerfeld studies of the two-dimensional Navier-Stokes equations. The asymptotic behavior of the model is investigated by transforming it to a traveling wave coordinate. Numerical integration of the traveling wave simplification of the model predicts the existence of chaotic large amplitude, non-periodic waves as observed in the experiments. The computed wave statistics such as wave celerities, rms values of film thickness, probability density functions and film thickness power spectra using the model are in good agreement with those measured on naturally excited fully developed flows at Re > 100. The present model also overcomes the main deficiency of the classical boundary layer models (namely, negative wall shear stress) predicts large amplitude waves (with peak to substrate ratios of 3 to 4) and better agreement with data. The model developed for free falling film is also extended to countercurrent gas-liquid flow and it is shown that an increase in the gas flow rate increases the average film thickness, peak to substrate ratio and wave velocities. The model also predicts the existence of recirculation regions within the large waves which are responsible for the observed enhancement in the transport rates.

Yu, Li-Qun

1995-01-01

422

High-pressure liquid chromatography analysis and single-dose disposition of tobramycin in human volunteers.  

PubMed Central

A sensitive and specific fluorometric high-pressure liquid chromatography technique was developed to measure both tobramycin and an internal standard (gentamicin C2). The assay utilizes direct extraction of the o-phthalaldehyde derivatives from serum and urine. Coefficients of variation were 7.9% (serum) and 6.0% (urine) at a tobramycin concentration of 1.0 microgram/ml. The lower limit of assay sensitivity was 0.2 microgram/ml. Results obtained from high-pressure liquid chromatography were in excellent agreement with those from radioimmunoassay for both serum (r = 0.97) and urine (r = 0.91). No other aminoglycoside antibiotics and no other antibiotics that were tested caused interfering peaks. Tobramycin (1 mg/kg intravenous bolus) was administered to three healthy volunteers. Tobramycin concentrations were detectable for 10 h in serum and for 240 h in urine after a 1-mg/kg intravenous dose. A two-compartment pharmacokinetic model was required to describe the tobramycin disposition. Urinary recovery of tobramycin over a 10-day period accounted for 95.8, 94.3, and 83.1% of the administered dose. High-pressure liquid chromatography methodology is sufficiently sensitive to determine single-dose, two-compartment tobramycin pharmacokinetics from urinary excretion data, thus verifying the prolonged excretion of tobramycin after a single dose. The analytical methodology and pharmacokinetic techniques described may be useful in studying other aminoglycosides. PMID:7396455

Haughey, D B; Janicke, D M; Adelman, M; Schentag, J J

1980-01-01

423

Simultaneous Analysis and Quantification of Markers of Manjisthadi Churna Using High Performance Thin Layer Chromatography  

PubMed Central

Manjisthadi churna has been traditionally used in the Ayurvedic system of medicine and by traditional medical practices of India to treat hyperlipidemia. A rapid, simple and accurate method with high performance thin layer chromatography has been developed to standardised Manjisthadi churna using rubiadin, sennoside and ellagic acid as markers. Methanol extract of Manjisthadi churna were used for high performance thin layer chromatography on silica gel plates. The Rf of rubiadin, sennoside-A and ellagic acid were found to 0.48, 0.23 and 0.72, respectively with densitometric scanning at 280 nm and the calibration plot were linear in the range of 100-600 ng of markers. The correlation coefficients were higher than 0.99 were indicative of good linear dependence of peaks area on concentration. The rubiadin, sennoside-A and ellagic acid contents in Manjisthadi churna were found to be 0.014, 0.038 and 0.534% w/w, respectively. This method permits reliable quantification of rubiadin, sennoside-A and ellagic acid with good resolution and separation of the same from other constitutes of the extract of Manjisthadi churna. Recovery value from 95.66-102.33% showed the reliability and reproducibility of the method. The proposed high performance thin layer chromatography method for simultaneous quantification of markers in Manjisthadi churna can be used for routine quality testing. PMID:23901170

Patel, V. R.; Patel, R. K.

2013-01-01

424

Headspace Single-Drop Microextraction Gas Chromatography Mass Spectrometry for the Analysis of Volatile Compounds from Herba Asari  

PubMed Central

A rapid headspace single-drop microextraction gas chromatography mass spectrometry (SDME-GC-MS) for the analysis of the volatile compounds in Herba Asari was developed in this study. The extraction solvent, extraction temperature and time, sample amount, and particle size were optimized. A mixed solvent of n-tridecane and butyl acetate (1?:?1) was finally used for the extraction with sample amount of 0.750?g and 100-mesh particle size at 70°C for 15?min. Under the determined conditions, the pound samples of Herba Asari were directly applied for the analysis. The result showed that SDME-GC–MS method was a simple, effective, and inexpensive way to measure the volatile compounds in Herba Asari and could be used for the analysis of volatile compounds in Chinese medicine. PMID:23607049

Wang, Guan-Jie; Tian, Li; Fan, Yu-Ming; Qi, Mei-Ling

2013-01-01

425

Analysis of kerogens by pyrolysis-gas chromatography-mass spectrometry using selective ion monitoring. III. Long-chain alkylbenzenes  

NASA Astrophysics Data System (ADS)

Analysis of the 3 principal kerogen types by pyrolysis-gas chromatography-mass spectrometry (P-GC-MS) has been undertaken using the mass spectrometer as a selective ion detector. By monitoring the fragment ions with {m}/{e} values of 91, 105 and 119 information has been obtained concerning differences in the content of long-chain alkylbenzenes in the kerogen pyrolysates, thus implying differences in the kerogen structures. Simulated maturation of the kerogens followed by specific ion ( {m}/{e} 105) gas chromatographic-mass spectrometric (GC-MS) analysis of the extracted liquid products, and specific ion ( {m}/{e} 105) GC-MS analysis of 3 crude oils is also described. The use of long-chain alkylbenzenes for geochemical correlation studies is discussed.

Solli, H.; Larter, S. R.; Douglas, A. G.

426

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

427

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

428

High Sensitivity Quantitative Lipidomics Analysis of Fatty Acids in Biological Samples by Gas Chromatography-Mass Spectrometry  

PubMed Central

Historically considered to be simple membrane components serving as structural elements and energy storing entities, fatty acids are now increasingly recognized as potent signaling molecules involved in many metabolic processes. Quantitative determination of fatty acids and exploration of fatty acid profiles have become common place in lipid analysis. We present here a reliable and sensitive method for comprehensive analysis of free fatty acids and fatty acid composition of complex lipids in biological material. The separation and quantitation of fatty acids is achieved by capillary gas chromatography. The analytical method uses pentafluorobenzyl bromide derivatization and negative chemical ionization gas chromatography-mass spectrometry. The chromatographic procedure provides base line separation between saturated and unsaturated fatty acids of different chain lengths as well as between most positional isomers. Fatty acids are extracted in the presence of isotope-labeled internal standards for high quantitation accuracy. Mass spectrometer conditions are optimized for broad detection capacity and sensitivity capable of measuring trace amounts of fatty acids in complex biological samples. PMID:21787881

Quehenberger, Oswald; Armando, Aaron M.; Dennis, Edward A.

2011-01-01

429

Analysis of cyanobacterial hepatotoxins in water samples by microbore reversed-phase liquid chromatography-electrospray ionisation mass spectrometry.  

PubMed

A method based on liquid chromatography coupled to mass spectrometry with positive electrospray ionisation was developed for the analysis of cyanobacterial hepatotoxins in environmental samples. The chromatographic separation was performed using two microbore columns, 2 mm and 1 mm I.D. columns, which allowed the coupling of liquid chromatography to mass spectrometry with no flow splitting. Analytes were eluted using two different water-acetonitrile, both acidified with formic acid gradients. Mass spectrometric parameters were optimised in order to maximise sensitivity. Detection limits for the 2 mm I.D. column ranged from 0.077 to 2.057 ng in full scan and from 0.021 to 1.153 ng in SIM mode. However, limits of detection as low as 60-340 pg in full scan and 6-72 pg in SIM mode were achieved for the 1 mm I.D. column. Finally, the proposed method was applied to the analysis of microcystins and nodularins in real samples. PMID:12141535

Barco, Mónica; Rivera, Josep; Caixach, Josep

2002-06-14

430

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

431

An Ultra-Trace Analysis Technique for SF6 Using Gas Chromatography with Negative Ion Chemical Ionization Mass Spectrometry.  

PubMed

Sulfur hexafluoride (SF6) is widely used as a tracer gas because of its detectability at low concentrations. This attribute of SF6 allows the quantification of both small-scale flows, such as leakage, and large-scale flows, such as atmospheric currents. SF6's high detection sensitivity also facilitates greater usage efficiency and lower operating cost for tracer deployments by reducing quantity requirements. The detectability of SF6 is produced by its high molecular electronegativity. This property provides a high potential for negative ion formation through electron capture thus naturally translating to selective detection using negative ion chemical ionization mass spectrometry (NCI-MS). This paper investigates the potential of using gas chromatography (GC) with NCI-MS for the detection of SF6. The experimental parameters for an ultra-trace SF6 detection method utilizing minimal customizations of the analytical instrument are detailed. A method for the detection of parts per trillion (ppt) level concentrations of SF6 for the purpose of underground ventilation tracer gas analysis was successfully developed in this study. The method utilized a Shimadzu gas chromatography with negative ion chemical ionization mass spectrometry system equipped with an Agilent J&W HP-porous layer open tubular column coated with an alumina oxide (Al2O3) S column. The method detection limit (MDL) analysis as defined by the Environmental Protection Agency of the tracer data showed the method MDL to be 5.2 ppt. PMID:25452581

Jong, Edmund C; Macek, Paul V; Perera, Inoka E; Luxbacher, Kray D; McNair, Harold M

2014-12-01

432

Analysis of Essential Oil in Jerusalem Artichoke (Helianthus tuberosus L.) Leaves and Tubers by Gas Chromatography-Mass Spectrometry  

PubMed Central

Purpose: To investigate, for the first time, the chemical composition of essential oil of the tubers and leaves of Jerusalem artichoke (Helianthus tuberosus L.), a species of sunflower native to eastern North America, growing in Ukraine. Methods: A hydrodistillation apparatus was used for the extraction of volatile components and then it was analysed by gas chromatography equipped with a split-splitless injector (split ratio, 1:50) and flame ionization detector (FID). The oil was analyzed under linear temperature programming applied at 4°C/min from 50°C - 340°C. Temperatures of the injector and FID detector were maintained at 280°C and 300°C, respectively. The chemical analysis of the oil was carried out using gas chromatography coupled to mass spectrometry (GC-MS), to determine the chemical composition of the volatile fraction. Results: The essential oils content ranged from 0.00019 to 0.03486 and 0.00011 to 0.00205 (g/100g), in leaves and tubers, respectively. The qualitative and quantitative analysis led to the identification of 17 components in both species samples. The major component found in leaves and tubers was (-)-?-bisabolene with 70.7% and 63.1%, respectively. Conclusion: Essential oil profile of Jerusalem artichoke species showed significant differences between leaves and tubers species. Additionally, the leaves of Jerusalem artichoke are a promising source of natural ?-bisabolene.

Helmi, Zead; Al Azzam, Khaldun Mohammad; Tsymbalista, Yuliya; Ghazleh, Refat Abo; Shaibah, Hassan; Aboul-Enein, Hassan

2014-01-01

433

Wall-To-Bulk Mass Transfer in a Gas Liquid Upflow Bubble Column  

NASA Astrophysics Data System (ADS)

Experiments have been carried out to investigate the effect of liquid and gas velocities, viscosity and gas hold-up on wall-to-bulk mass transfer coefficient in a gas-liquid upflow bubble column using limiting current technique. The system chosen was an electrolyte as liquid phase and inert nitrogen as gas phase. The electrolyte was an equimolar solution of potassium ferricyanide and potassium ferrocyanide of 0.01 N with 0.5 N sodium hydroxide as indifferent electrolyte. To vary the viscosity carboxy methyl cellulose sodium salt (CMC) in 0.1, 0.2 and 0.4 wt% was added to the electrolyte. The reaction considered was the reduction of ferricyanide ion. The experiments were carried out at constant temperature of 25 °C at which the physical property values of the electrolyte were known from literature. The mass transfer coefficient was computed from the measured limiting current. It was found that the mass transfer coefficient was relatively independent of liquid velocity with in the range covered in the present experiment. The kL increased with increasing gas velocity and gas holdup. The kL was observed to decrease with increasing CMC concentration. The entire experimental data have been correlated in terms of Colburn j-factor, Reynolds number and modified Froude number.

Raju, G. M. J.; Ramesh, K. V.; Sarma, G. V. S.

2013-09-01

434

A computational study of axial dispersion in segmented gas-liquid flow  

NASA Astrophysics Data System (ADS)

Axial dispersion of a tracer in a two-dimensional gas-liquid flow is studied computationally using a finite-volume/front-tracking method. The effects of Peclet number, capillary number, and segment size are examined. At low Peclet numbers, the axial dispersion is mainly controlled by the convection through the liquid films between the bubbles and channel walls. In this regime, the computational results are found to be in a very good agreement with the existing model due to Pedersen and Horvath [Ind. Eng. Chem. Fundam. 20, 181 (1981)]. At high Peclet numbers, the axial dispersion is mainly controlled by the molecular diffusion, with some convective enhancement. In this regime, a new model is proposed and found to agree well with the computational results. These Peclet number regimes are shown to persist for different slug lengths. The axial dispersion is found to depend weakly on the capillary number in the diffusion-controlled regime. Finally, computational simulations are performed for the cases of six bubbles to mimic bubble trains, and results are compared with the theoretical models.

Muradoglu, Metin; Günther, Axel; Stone, Howard A.

2007-07-01

435

Dynamic QM/MM: a hybrid approach to simulating gas-liquid interactions.  

PubMed

In this chapter we describe molecular dynamics simulation methods in which the system being studied is divided into a region where quantum mechanics (QM) is used to determine forces for doing Born-Oppenheimer direct dynamics calculations (i.e., doing electronic structure calculations on the fly to determine energies and forces) and another region where empirical potentials that are commonly used in molecular mechanics (MM) calculations are used to determine forces. The two regions are linked through an embedding process that may or may not involve the possibility that atoms can be passed back and forth between regions at each time step. The idea with this dynamic QM/MM methodology is that one uses QM calculations to define the potential surface in portions of the system where reaction occurs, and MM to determine forces in what is typically a much larger region where no reaction occurs. This approach thereby enables the description of chemical reactions in the QM region, which is a technology that can be used in many different applications. We illustrate its use by describing work that we have done with gas-liquid reactions in which a reactive atom (such as an oxygen or fluorine atom) reacts with the surface of a liquid and the products can either remain in the liquid or emerge into the gas phase. Applications to hydrocarbon and ionic liquids are described, including the characterization of reaction mechanisms at hyperthermal energies, and the determination of product branching and product energy distributions. PMID:21506003

Yockel, Scott; Schatz, George C

2012-01-01

436

Abnormal microchannel convective fluid flow near the gas-liquid critical point  

NASA Astrophysics Data System (ADS)

This article deals with a CO2 critical microchannel convective flow with heat applied from two side walls. Fluid near its gas-liquid critical point is very dense and much expandable; meanwhile, the thermal diffusivity tends to zero when it goes near the critical point. In microchannels, the effect of natural convection becomes negligible and the boundary thermal-mechanical effects will dominate the convection and thermal equilibrium processes. We numerically simulate the convection behaviours of near-critical fluids confined in microchannels by solving the Navier-Stokes equations together with conservative equations of mass and energy. Due to the thermal-mechanical effects of critical fluid, abnormal convection-onset structures and transient micro-scale vortex/mixing evolution modes have been found. The thermal-mechanical/acoustic perturbation source identified here contributes to a new type of Kelvin-Helmholtz instability when gravity is suppressed. The thermal-mechanical oscillations in the boundaries serve as the origin of current vortex phenomena from fast boundary expansion and density stratification. The abnormal microchannel vortex evolution and instability mechanisms/threshold are also discussed in detail in this article.

Chen, Lin; Zhang, Xin-Rong; Okajima, Junnosuke; Maruyama, Shigenao

2014-03-01

437

Design and Development of Gas-Liquid Cylindrical Cyclone Compact Separators for Three-Phase Flow  

SciTech Connect

The objective of this five-year project (October 1997--September 2002) was to expand the current research activities of Tulsa University Separation Technology Projects (TUSTP) to multiphase oil/water/gas separation. This project was executed in two phases. Phase I (1997--2000) focused on the investigations of the complex multiphase hydrodynamic flow behavior in a three-phase Gas-Liquid Cylindrical Cyclone (GLCC) Separator. The activities of this phase included the development of a mechanistic model, a computational fluid dynamics (CFD) simulator, and detailed experimentation on the three-phase GLCC. The experimental and CFD simulation results will be suitably integrated with the mechanistic model. In Phase II (2000--2002), the developed GLCC separator will be tested under high pressure and real crude conditions. This is crucial for validating the GLCC design for field application and facilitating easy and rapid technology deployment. Design criteria for industrial applications will be developed based on these results and will be incorporated into the mechanistic model by TUSTP.

Mohan, R.S.; Shoham, O.

2001-01-10

438

Effect of impeller geometry on gas-liquid mass transfer coefficients in filamentous suspensions  

SciTech Connect

Volumetric gas-liquid mass transfer coefficients were measured in suspensions of cellulose fibers with concentrations ranging from 0 to 20 g/L. The mass transfer coefficients were measured using the dynamic method. Results are presented for three different combinations of impellers at a variety of gassing rates and agitation speeds. Rheological properties of the cellulose fibers were also measured using the impeller viscometer method. Tests were conducted in a 20 L stirred-tank fermentor and in 65 L tank with a height to diameter ratio of 3:1. Power consumption was measured in both vessels. At low agitation rates, two Rushton turbines gave 20% better performance than the Rushton and hydrofoil combination and 40% better performance than the Rushton and propeller combination for oxygen transfer. At higher agitation rates, the Rushton and hydrofoil combination gave 14 and 25% better performance for oxygen transfer than two Rushton turbines and the Rushton and hydrofoil combination, respectively. 8 refs., 11 figs., 1 tab.

Dronawat, S.N.; Svihla, C.K.; Hanley, T.R. [Univ. of Louisville, KY (United States)

1997-12-31

439

Effects of Gravity on Cocurrent Two-Phase Gas-Liquid Flows Through Packed Columns  

NASA Technical Reports Server (NTRS)

This work presents the experimental results of research on the influence of gravity on flow pattern transitions, pressure drop and flow characteristics for cocurrent gas-liquid two-phase flow through packed columns. The flow pattern transition data indicates that the pulse flow regime exists over a wider range of gas and liquid flow rates under reduced gravity conditions compared to normal gravity cocurrent down-flow. This is illustrated by comparing the flow regime transitions found in reduced gravity with the transitions predicted by Talmor. Next, the effect of gravity on the total pressure drop in a packed column is shown to depend on the flow regime. The difference is roughly equivalent to the liquid static head for bubbly flow but begins to decrease at the onset of pulse flow. As the spray flow regime is approached by increasing the gas to liquid ratio, the effect of gravity on pressure drop becomes negligible. Finally, gravity tends to suppress the amplitude of each pressure pulse. An example of this phenomenon is presented.

Motil, Brian J.; Balakotaiah, Vemuri; Kamotani, Yasuhiro

2001-01-01

440

Gas-liquid Phase Distribution and Void Fraction Measurements Using the MRI  

NASA Technical Reports Server (NTRS)

We used a permanent-magnet MRI system to estimate the integral and spatially- and/or temporally-resolved void-fraction distributions and flow patterns in gas-liquid two-phase flows. Air was introduced at the bottom of the stagnant liquid column using an accurate and programmable syringe pump. Air flow rates were varied between 1 and 200 ml/min. The cylindrical non-conducting test tube in which two-phase flow was measured was placed in a 2.67 kGauss MRI with MRT spectrometer/imager. Roughly linear relationship has been obtained for the integral void-fraction, obtained by volume-averaging of the spatially-resolved signals, and the air flow rate in upward direction. The time-averaged spatially-resolved void fraction has also been obtained for the quasi-steady flow of air in a stagnant liquid column. No great accuracy is claimed as this was an exploratory proof-of-concept type of experiment. Preliminary results show that MRI a non-invasive and non-intrusive experimental technique can indeed provide a wealth of different qualitative and quantitative data and is especially well suited for averaged transport processes in adiabatic and diabatic multi-phase and/or multi-component flows.

Daidzic, N. E.; Schmidt, E.; Hasan, M. M.; Altobelli, S.

2004-01-01

441

Generating Singlet Oxygen Bubbles: A New Mechanism for Gas-Liquid Oxidations in Water  

PubMed Central

Laser-coupled microphotoreactors were developed to bubble singlet oxygen [1O2 (1?g)] into an aqueous solution containing an oxidizable compound. The reactors consisted of custom-modified SMA fiber-optic receptacles loaded with 150-?m silicon phthalocyanine glass sensitizer particles, where the particles were isolated from direct contact with water by a membrane adhesively bonded to the bottom of each device. A tube fed O2 gas to the reactor chambers. In the presence of O2, singlet oxygen was generated by illuminating the sensitizer particles with 669-nm light from an optical fiber coupled to the top of the reactor. The generated 1O2 was transported through the membrane by the O2 stream and formed bubbles in solution. In solution, singlet oxygen reacted with probe compounds (either 9,10-anthracene dipropionate dianion, trans-2-methyl-2-pentanoate anion, N-benzoyl-D,L-methionine, and N-acetyl-D,L-methionine) to give oxidized products in two stages. The early stage was rapid and showed that 1O2 transfer occurred via bubbles mainly in the bulk water solution. The later stage was slow, it arose only from 1O2-probe molecule contact at the gas/liquid interface. A mechanism is proposed that involves 1O2 mass transfer and solvation, where smaller bubbles provide better penetration of 1O2 into the flowing stream due to higher surface-to-volume contact between the probe molecules and 1O2. PMID:22260325

Bartusik, Dorota; Aebisher, David; Ghafari, BiBi

2012-01-01

442

Measuring holdup in gas-liquid two-phase flow with ultrasonics  

SciTech Connect

The authors investigated the feasibility of using ultrasonic measurements to determine the volume fraction of gas (void fraction) in vertical upwards gas/liquid bubble flow in pipe. The measurements were performed with standard immersion-type ultrasonic transducers mounted on special traversing arms and facing each other across the inside diameter of the 7.25 in. ID acrylic pipe used in the study. The measurements were observed to be very sensitive to changes in void fraction; the ultrasonic extinction showed an exponential decay with increasing void fraction so that the signal intensity diminished by twelve orders of magnitude as the void fraction increased from 0 to about 13% in flow loop experiments and about five to eight orders of magnitude for the same range of void fractions for air bubbling through a stagnant water column. The change in extinction was found to be systematic and repeatable in both systems, but the rate of change with varying void fraction was different for each system. The different responses for the different systems are attributed to variations in bubble-size distributions and are predicted by the various theories of wave propagation in random media.

Maher, T.F. [Shell Offshore, New Orleans, LA (United States); Hill, A.D.; Morriss, S.L. [Univ. of Texas, Austin, TX (United States). Dept. of Petroleum and Geosystems Engineering

1996-09-01

443

Two-dimensional gas chromatography with heart-cutting for isotope ratio mass spectrometry analysis of steroids in doping control.  

PubMed

The accuracy and precision of gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS) measurements are highly dependent on analyte purity. Reliable analysis of urinary steroids for doping control therefore requires extensive and time-consuming sample preparation (i.e. liquid chromatography fraction collection) prior to GC-C-IRMS analysis. The use of two-dimensional GC (GC-GC) with heart-cutting (Deans Switch) as a possible approach to reduce the sample purification required for IRMS analysis is described herein. The system uses a low thermal mass oven (LTM) incorporated into an existing GC-C-IRMS system. GC-GC allowed the use of a cyanopropyl/phenyl column in the first dimension to optimize the separation of underivatized steroids, while a phenyl-methylpolysiloxane column in the second dimension focuses the selectively cut analytes into narrower peaks for more sensitive and reliable MS analysis. In addition, to confirm analyte identity, eluent from the second GC was split, with 20 % entering a scanning MS, and 80 % flowing to the IRMS. As a proof concept, the developed method was then used to analyze a single spot urine (5 ml) from an individual receiving T therapy (2 × 50 mg sachets of Testogel(®)). The T delta value (-27.8 ‰, [T]?= 38 ng/ml) was clearly distinct from 11-ketoetiocholanolone (-22.5 ‰) (used as an endogenous reference compound (ERC)), indicating T as being of exogenous origin. The simultaneous analysis by the scanning MS yielded a full scan mass spectrum of the same chromatographic peak, thus confirming the peak to be T. PMID:22761127

Brailsford, A D; Gavrilovi?, I; Ansell, R J; Cowan, D A; Kicman, A T

2012-12-01

444

Ultra-Trace Analysis of Nine Macrolides, including Tulathromycin A (Draxxin), in Edible Animal Tissues with Mini-Column Liquid Chromatography Tandem Mass Spectrometry  

Technology Transfer Automated Retrieval System (TEKTRAN)

Analysis of 9 macrolides is presented, including tulathromycin A (Draxxin), in beef, poultry and pork muscle with a simple multi-residue extraction and analysis method using high performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry. The extraction method inv...

445

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

446

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.

447

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

448

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

449

[Application of turbulent flow chromatography in the analysis of biological samples].  

PubMed

The complexity of biological fluids makes the sample preparation necessary in the analytical process. The traditional techniques, such as liquid-liquid extraction and solid-phase extraction, are time-consuming and labor-intensive. Turbulent flow chromatography (TFC), as an on-line direct injection technique, possesses the advantages of reducing sample preparation steps and enabling the effective pre-concentration and clean-up of biological fluids. Therefore, it is a high-throughput and high-selectivity technique for biological sample pretreatment. In this review, the theory, advantages, characteristics and current status of TFC in bioanalysis are introduced and summarized. PMID:20556956

Liu, Peng; Zhou, Jianliang; An, Jingjing; Li, Ping

2010-02-01

450

Rapid Fc glycosylation analysis of Fc fusions with IdeS and liquid chromatography mass spectrometry  

PubMed Central

We developed a rapid method to analyze Fc glycosylation of Fc fusion proteins, especially those with mutated Fc hinge regions. Fc fusion proteins were digested with IdeS, an IgG specific protease with exosites for substrate recognition and cleavage. The resultant fragments were directly analyzed through liquid chromatography mass spectrometry. The structures and relative quantities of Fc glycans were deduced from their masses and intensities. The separated substrate recognition and cleavage property of IdeS makes this method applicable to a broad range of Fc fusion proteins having either standard or non-canonical hinge regions. PMID:23839239

Lynaugh, Heather; Li, Huijuan; Gong, Bing

2013-01-01

451

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

452

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

453

Background correction for fluorescence detection in thin-layer chromatography using factor analysis and the adaptive Kalman filter  

SciTech Connect

A method is proposed that corrects for variable background signals. This technique has been applied to the analysis of polyaromatic hydrocarbons using high-performance thin-layer chromatography with fluorescence detection. The fluorescent background from thin-layer plates was found to be highly variable, and simple background subtraction yielded imprecise and inaccurate concentration estimates. The method proposed here is based on the assumption that variable background signals can be modeled by the abstract spectra obtained from factor analysis of several background spectra, and the appropriate weighting factors can then be calculated by using the adaptive Kalman filter. It was found that the best models were obtained by selecting spectra from random locations across the thin-layer plate, as opposed to spectra from a blank lane or spectra adjacent to the analyte zone. This approach gave concentration estimates with improved accuracy and precision, in most cases, when compared to simple subtraction.

Gerow, D.D.; Rutan, S.C.

1988-05-01

454

Floral classification of honey using liquid chromatography-diode array detection-tandem mass spectrometry and chemometric analysis.  

PubMed

A high performance liquid chromatography-diode array detection-tandem mass spectrometry (HPLC-DAD-MS/MS) method for the floral origin traceability of chaste honey and rape honey samples was firstly presented in this study. Kaempferol, morin and ferulic acid were used as floral markers to distinguish chaste honey from rape honey. Chromatographic fingerprinting at 270 nm and 360 nm could be used to characterise chaste honey and rape honey according to the analytical profiles. Principal component analysis (PCA), partial least squares (PLS), partial least squares-discrimination analysis (PLS-DA) and soft independent modeling of class analogy (SIMCA) were applied to classify the honey samples according to their floral origins. The results showed that chaste honey and rape honey could be successfully classified by their floral sources with the analytical methods developed through this study and could be considered encouraging and promising for the honey traceability from unifloral or multifloral nectariferous sources. PMID:24128567

Zhou, Jinhui; Yao, Lihu; Li, Yi; Chen, Lanzhen; Wu, Liming; Zhao, Jing

2014-02-15

455

Analysis of nitrofuran metabolites in food by high-performance liquid chromatography with tandem mass spectrometry detection.  

PubMed

A reliable and sensitive procedure is presented for the analysis of nitrofuran metabolite residues in foods of animal origin, like poultry and shrimp. The method is based on a one-step extraction/derivatization, followed by solid-phase extraction clean-up with polymeric phase cartridges. The separations were carried out by liquid chromatography coupled with tandem mass spectroscopy detection. Results from the full validation of the procedure and from a survey of food available from the Swiss market, with the analysis of 236 samples of shrimp, poultry, fish and rabbit, are presented and demonstrate that this method is satisfactory in order to control nitrofuran residues in foods of animal origin. PMID:14708885

Edder, Patrick; Vargas, Sandra; Ortelli, Didier; Corvi, Claude

2003-12-01

456

Application of electrical resistance tomography system to monitor gas\\/liquid two-phase flow in a horizontal pipe  

Microsoft Academic Search

The Electrical Resistance Tomography (ERT) technique possesses great potential in monitoring widely exiting industrial two\\/multi-phase flow. For vertical pipe flow and inclined pipe flow, some application studies with exciting results have been reported, but there is rarely a paper regarding the application of ERT to horizontal gas\\/liquid pipe flow. This paper addresses this issue and proposes a smart method, Liquid

Yixin Ma; Zhichu Zheng; Ling-an Xu; Xiaoping Liu; Yingxiang Wu

2001-01-01

457

Gas\\/Liquid Two-Phase Flow Regime Recognition Based on Adaptive Wavelet-Based Neural Network  

Microsoft Academic Search

Flow regime recognition of two-phase flow is of great importance in industrial process. In this paper, a new method is brought forward to recognize the gas\\/liquid two-phase flow regime. The information of the method that provided by electrical resistance tomography (ERT) is the measured data in horizontal pipe. A new adaptive wavelet-based neural network was introduced and it combines the

Jun Han; Feng Dong; Yaoyuan Xu

2008-01-01

458

An investigation on near wall transport characteristics in an adiabatic upward gas–liquid two-phase slug flow  

Microsoft Academic Search

The near-wall transport characteristics, inclusive of mass transfer coefficient and wall shear stress, which have a great\\u000a effect on gas–liquid two-phase flow induced internal corrosion of low alloy pipelines in vertical upward oil and gas mixing\\u000a transport, have been both mechanistically and experimentally investigated in this paper. Based on the analyses on the hydrodynamic\\u000a characteristics of an upward slug unit,

Donghong Zheng; Defu Che

2007-01-01

459

Experimental investigation on gas–liquid two-phase slug flow enhanced carbon dioxide corrosion in vertical upward pipeline  

Microsoft Academic Search

The carbon dioxide corrosion behavior of API N80 grade steel enhanced by gas–liquid two-phase vertical upward slug flow has been both mechanistically and experimentally investigated. It is found that the hydrodynamic characteristics of slug flow, such as the direction alternated wall shear stress, the fluctuation of wall normal stress, and the mass transfer near the wall, have significant effects on

Donghong Zheng; Defu Che; Yinhe Liu

2008-01-01

460

Prediction of the transition from stratified to slug flow or roll-waves in gas–liquid horizontal pipes  

Microsoft Academic Search

In stratified gas–liquid horizontal pipe flow, growing long wavelength waves may reach the top of the pipe and form a slug flow, or evolve into roll-waves. At certain flow conditions, slugs may grow to become extremely long, e.g. 500 pipe diameter. The existence of long slugs may cause operational upsets and a reduction in the flow efficiency. Therefore, predicting the

U. Kadri; R. F. Mudde; R. V. A. Oliemans; M. Bonizzi; P. Andreussi

2009-01-01