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Topic: Gas liquid chromatography

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Chromatography - Wikipedia, the free encyclopedia Gas-liquid chromatography is based on a partition equilibrium of analyte between a liquid stationary phase and a mobile gas. Chromatography is a separation method that exploits the differences in partitioning behavior between a mobile phase and a stationary phase to separate the components in a mixture. Chromatography is a family of analytical chemistry techniques for the separation of mixtures. en.wikipedia.org /wiki/Chromatography   (2346 words)

Gas-liquid chromatography - Wikipedia, the free encyclopedia Gas-liquid chromatography (GLC), or simply gas chromatography (GC), is a type of chromatography in which the mobile phase is a carrier gas, usually an inert gas such as helium or nitrogen, and the stationary phase is a microscopic layer of liquid on an inert solid support. One example of the use of gas chromatography is in the study of the selectivity of Fischer-Tropsch synthesis catalysts. Although the carrier gas sweeps the analyte molecules through the column, this motion is inhibited by the adsorption of the analyte molecules either onto the column walls or onto packing materials in the column. en.wikipedia.org /wiki/Gas_chromatograph   (786 words)

gas liquid chromatography Gas-liquid chromatography (GC) was in invented by James and Martin and is a chromatography separation technique in which the mobile phase is a gas (usually helium or nitrogen) and the stationary phase is a liquid. Martin and Synge recommended that the liquid mobile phase used in liquid chromatography could be replaced by a suitable gas. Early Gas Chromatography Detectors The first GC detector was invented by James and Martin [4] in 1952, and used for the separation of some fatty acids. www.chromatography-online.org /topics/gas/liquid/chromatography.html   (1044 words)

Gas chromatography - Analytical methods AGA Region Europe North Gas-liquid chromatography is useful for separating ions or molecules that are dissolved in a solvent. Gas chromatography is also used to monitor industrial processes automatically: gas streams are analyzed periodically and manual or automatic responses are made to counteract undesirable variations. Chromatography is a technique for separating chemical substances that relies on differences in partitioning behavior between a flowing mobile phase and a stationary phase to separate the components in a mixture. hiq.aga.se /International/Web/LG/DK/likelgspgdk.nsf/DocByAlias/anal_gaschrom   (997 words)

GAS-LIQUID CHROMATOGRAPHY In gas-liquid chromatography, GLC, the chemical compounds are carried through a column using an inert carrier gas as nitrogen, helium or hydrogen. Chromatography is a technique for separating and determining the components of a mixture. The retardation of the compounds is achieved by the stationary phase that is immobilised on the inner surface of the column. www.nada.kth.se /~henrry/DomainGenerator/WSP/WSP00/Hans2first.html   (314 words)

Gas Chromatography Gas chromatography - specifically gas-liquid chromatography - involves a sample being vapourised and injected onto the head of the chromatographic column. A non-selective detector responds to all compounds except the carrier gas, a selective detector responds to a range of compounds with a common physical or chemical property and a specific detector responds to a single chemical compound. The choice of carrier gas is often dependant upon the type of detector which is used. www.shu.ac.uk /schools/sci/chem/tutorials/chrom/gaschrm.htm   (940 words)

BISC 429 In gas chromatography, the mobile phase is a gas that is moved through the column, while the stationary phase is a liquid film that coats the column filling (in packed columns) or the column wall (in capillary columns). Gas chromatography is a very sensitive method for the separation and quantification of chemicals, and it is perfect for the analysis of fatty acid components. Compounds must be present in the gas phase so that partition between the gaseous mobile phase and the liquid stationary phase is possible. www.sfu.ca /bisc/bisc-429/GLC.html   (2762 words)

Supercritical Fluid Chromatography Gas and Liquid Chromatography are arguably two of the most useful analytical techniques in both academia and industrial chemistry. This technique truly appears to be a hybrid of gas and liquid chromatography aimed at improving some of the shortcomings of each of the other techniques. For instance, the general resolution obtained through standard gas chromatography is far superior to that obtained from liquid chromatography. franklin.chm.colostate.edu /kimball/teaching/c531/Essays/Schnarr.htm   (641 words)

Chromatographic analysis of hydrocarbon mixtures - Patent 4384471 In gas-liquid chromatography, a mobile phase, such as a gaseous stream of nitrogen or helium containing a mixture of solutes is passed over a stationary phase of a nonvolatile liquid which is evenly distributed as a thin layer on a noninteracting solid support. Following separation by compound type, each group is resolved and identified by gas liquid chromatography. This affinity is referred to as the partition coefficient and is the ratio of the concentration of a species in the stationary (liquid) phase to its concentration in the mobile (gas) phase. www.freepatentsonline.com /4384471.html   (6281 words)

Organic_Labs_1.doc Gas-liquid chromatography is a method for separation of volatile material, using a special separating column. Intro: In this experiment, the nucleophilicities of bromide and chloride ions were measured by Gas-Liquid Chromatography analysis of their reaction on 1-butanol catalysed by sulphuric acid. Separation is effected using differences in the partition coefficient of the material to be separated, the partition being between liquid and gas Procedure: As opposed to the method described in the manual, the correct concentration of sulphuric acid was provided and this was used. www.maths.tcd.ie /~pwalsht/labs/Organic_Labs_1.doc   (454 words)

UNODC - Bulletin on Narcotics - 1984 Issue 1 - 002 Gas chromatography can only analyse compounds in the gaseous phase; the compounds to be analysed have to be volatile in nature or derivatized into volatile agents. Until recently, gas chromatography was the best and most widely used method for the quantification of heroin and other opiate drugs in illicit traffic on a routine basis. Analysis of drugs and metabolites by gas chromatography, mass spectrometry. www.unodc.org /unodc/fr/bulletin/bulletin_1984-01-01_1_page003.html   (2684 words)

ScienceDaily: Quantum Cascade Lasers Key To Handheld Gas And Liquid Sensors As with the gas devices, the quantum cascade lasers vastly increase the sensitivity of liquid phase chemical detection at the surface of this waveguide. Liquid -- A liquid is one of the three ordinary phases of matter. A colorless noble gas, krypton occurs in trace amounts in the atmosphere, is isolated by fractionating liquefied air, and is... www.sciencedaily.com /releases/2005/08/050805105409.htm   (1477 words)

Liquid Chromatography Clue Next Liquid Chromatography Assets An apparatus for liquid chromatography comprises a liquid chromatography separation column on a substrate, wherein the separation column is coupled to a heater on the substrate. A chip-based temperature controlled liquid chromatography device comprises a substrate, a thermal isolation zone, and a separation column thermally isolated from the substrate by... A liquid ejection apparatus comprises a liquid cartridge for storing a liquid, a liquid ejection head for ejecting the liquid toward a target, a liquid supply path for guiding the liquid to the liquid ejection head from the liquid cartridge, and a capping device for drawing the liquid from the... liquidchromatography.seisliquid.com   (1077 words)

Gas Chromatography Much of the early work in gas chromatography involved separating hydrocarbon mixtures such as gasoline on columns in which the liquid phase was a silicone oil. Because the mobile phase is gas, solubility in the mobile phase is not really a factor, but volatility (vapor pressure) of the components being analyzed is a close equivalent. The liquid (coating) is now very often a polymer that resists bleeding and decomposition, and which may improve selectivity for certain types of molecules. www.dyerlabs.com /chemistry/gas.html   (1850 words)

gas chromatography --  Encyclopædia Britannica Gas chromatography employing a gaseous fluid as the mobile phase, called the carrier gas, is subdivided into gas-solid chromatography and gas-liquid chromatography. The mobile phase may be either a liquid or a gas, while the stationary phase is either a solid or a liquid. in analytical chemistry, technique for separating chemical substances in which the sample is carried by a moving gas stream through a tube packed with a finely divided solid that may be coated with a film of a liquid. www.britannica.com /eb/article-9036136   (705 words)

Coupled assay of sphingomyelin and ceramide molecular species by gas liquid chromatography -- Vieu et al. 43 (3): 510 -- Journal of Lipid Research Gas liquid chromatography was performed on a Restek 50 capillary column as described in Materials and Methods. gas liquid chromatography (GLC), or HPLC (12) (13) (14) (15) Gas liquid chromatogram of the neutral lipid molecular species of plasma (40 µl) before (A) and after (B) mild alkaline treatment of lipids. www.jlr.org /cgi/content/full/43/3/510   (5620 words)

JAIC 1998, Volume 37, Number 3, Article 4 (pp. 294 to 311) Her research focused on development and application of gas and high performance liquid chromatographic methods for identification of artists' proteinaceous and natural gum binding media, ultimate aim of project being study of late-18th- and early-19th-century works by artists such as William Blake, J.M.W. Turner, and D. Rossetti. Preparation and gas chromatography of highly volatile trifluoroacetylated carbohydrates using N-methyl bis[trifluoroacet-amide]. A gas chromatographic method for the determination of aldose and uronic acid constituents of plant cell wall polysaccharides. aic.stanford.edu /jaic/articles/jaic37-03-004_appx.html   (1259 words)

The clinical value of gas-liquid chromatography in the detection of intra-amniotic microbial invasion -- Romero et al. 72 (1): 44 -- Obstetrics & Gynecology Short-chain organic acids are byproducts of bacterial metabolism, and their detection by gas-liquid chromatography (GLC) in amniotic fluid has been proposed as a rapid, sensitive, and specific method for the diagnosis of infection. This study was conducted to determine whether GLC analysis of amniotic fluid would be helpful in a population of women in whom the Gram stain examination was negative. In group 3, the sensitivity of GLC was 28.5% and the specificity was 55.5%. www.greenjournal.org /cgi/content/abstract/72/1/44   (240 words)

Chromatography Research in the Siepmann Group Gas-liquid and reversed-phase liquid chromatography are the principal methods for the analysis and separation of organic and biological molecules, as evidenced by their extensive use throughout the scientific community. A molecular simulation study of the bonded-phase structure in reversed-phase liquid chromatography with neat aqueous solvent The main goals of our research on retention mechanisms in chromatography are to provide microscopic-level insight into chromatographic separation processes and to predict retention times using novel simulation techniques and transferable force fields. www.chem.umn.edu /groups/siepmann/research/chrom.php   (539 words)

Chem2O06 - 1997/98 - Experiment 4A: Nucleophilic Substitution and Gas Liquid Chromatography Part A: Nucleophilic Substitution and Gas Liquid Chromatography. The carrier gas (mobile phase) is usually nitrogen (but sometimes argon, helium, or hydrogen) and passes continuously through the column throughout its operation. Be very careful inserting your thermometer into the glass-to-rubber adaptor; use a little glycerol as lubricant and grasp the thermometer close to the adaptor as you push it in. www.chemistry.mcmaster.ca /~chem2o6/labmanual/expt4/exp4a-p.html   (1361 words)

Determination of Atmospheric Atrazine and Alchlor Concentrations by Reverse Phase Liquid Chromatography and Gas Chromatography Mass Spectrometry Both high performance liquid chromatography with ultraviolet detection (HPLC/UV) and gas chromatography with mass spectrometric detection (GC/MS) were used for identification and quantification of atmospheric herbicide concentrations. Determination of Atmospheric Atrazine and Alachlor Concentrations By Reverse Phase Liquid Chromatography and Gas Chromatography Mass Spectrometry Determination of Atmospheric Atrazine and Alchlor Concentrations by Reverse Phase Liquid Chromatography and Gas Chromatography Mass Spectrometry carbon.cudenver.edu /~landerso/97ra12203.htm   (5165 words)

UNODC - Bulletin on Narcotics - 1985 Issue 1 - 005 Gas-liquid chromatography separations are found to be complicated by the instability of two diastereoisomers (allococaine and allopseudococaine). As mentioned earlier, if cocaine is to be quantified by gas-liquid chromatography the sample should be converted to the free base prior to injection to minimize decomposition in the injection port [ 73]. Analysis of the alkaloids extracted from leaves has been accomplished by gas-liquid chromatography in combination with mass fragmentography and stable isotope dilution [ 16], and by gas-liquid chromatography alone [ 17] [ 18] [ 19]. www.unodc.org /unodc/fr/bulletin/bulletin_1985-01-01_1_page006.html   (5736 words)

Biotech Bunny: Liquid Chromatography High performance liquid chromatography (HPLC) is similar to reverse phase, only in this method, the process is conducted at a high velocity and pressure drop. They are reverse phase, high performance and size exclusion liquid chromatography, along with supercritical fluid chromatography. Reverse phase chromatography is a powerful analytical tool and involves a hydrophobic, low polarity stationary phase which is chemically bonded to an inert solid such as silica. www.rpi.edu /dept/chem-eng/Biotech-Environ/CHROMO/chromliquid.html   (293 words)

Used and refurbished high quality gas and liquid chromatography systems, HPLC, GC. High pressure liquid chromatography was developed in the mid-1970's and quickly improved with the development of column packing materials and the additional convenience of on-line detectors. During this time, pressure liquid chromatography began to be used to decrease flowthrough time, thus reducing purification times of compounds being isolated by column chromatogaphy. In the late 1970's, new methods including reverse phase liquid chromatography allowed for improved separation between very similar compounds. www.gclctoronto.com   (554 words)

Advisory Opinion: Gas Chromatography Field Analysis Gas chromatography is used to separate a mixture of closely-related compounds into the individual compounds for measurement. One of two common techniques are used to move the contaminants from a liquid (either a water sample or the liquid from soil extraction) into the gaseous phase: static headspace or purge and trap. The stationary phase is an organic liquid compound that is either coated on or covalently bonded to the silica surface of a capillary column. www.newmoa.org /Newmoa/htdocs/cleanup/advisory/gc.htm   (4848 words)

125GCAlc.htm In gas-liquid chromatography, separation is done by partitioning the components of a chemical mixture between a mobile phase and a stationary liquid phase held in a column. Quantitative chromatography is based upon the comparison of the area of the analyte peak with that of one or more standards. The sample is vaporized immediately and transported onto the column by the carrier gas. www.accd.edu /nvc/areas/chem/Chem125/125GCAlc.htm   (870 words)

LIQUID CHROMATOGRAPHY In Liquid-Liquid Chromatography the stationary solid surface is coated with a 2nd liquid (the Stationary Phase) which is immiscible Gel-Permeation Chromatography is a mechanical sorting of molecules based on the size of the molecules in solution. Separation in Ion-exchange Chromatography is based on the competition of different ionic compounds of the sample for the active sites on the ion-exchange resin (column-packing). class.fst.ohio-state.edu /fst601/Lectures/Liqchr.htm   (321 words)

Evaluation of Data for the Gas-Liquid Chromatography The net retention time is a measure of the partition of the solute between the gas (mobile) phase and the stationary phase (solvent). In order to examine the presence of adsorption effects, it is necessary to vary the relative amount of stationary phase (liquid loading) or the sample volume of injected solutes. the following informations are required: the net retention time of the solute, the temperature, column inlet and outlet pressure, the carrier gas flow rate, and the amount of the stationary phase on the solid support. www.uni-oldenburg.de /tchemie/Exp_GLC_Data_Eval.html   (314 words)

Gas Chromatography Services - Worldwide Gas and liquid chromatography specialists for service, validation and consumables. Greyhound Chromatography and Allied Chemicals was established in 1981 to serve the chromatography industry as a single source supplier of products from the worlds leading manufacturers of chromatography consumables and certified reference standards. Today, Greyhound Chromatography and Allied Chemicals - known in the industry as 'Greyhound' - offers the broadest range of chromatography products, chemicals and chemical reference standards available from any single source. www.kellysearch.com /qz-product-124439.html   (741 words)

D1983-90(1995)e1 Standard Test Method for Fatty Acid Composition by Gas-Liquid Chromatography of Methyl Esters (Withdrawn 2003) Fatty acids-general; Gas chromatography (GC)-paints/related coatings/materials; Methyl esters; fatty acid composition, by gas-liquid chromatography of methyl esters,; test,; Fatty acids content; fatty acid composition, by gas-liquid chromatographyof methyl esters,; test; 87.060.20 WITHDRAWN STANDARD: D1983-90(1995)e1 Standard Test Method for Fatty Acid Composition by Gas-Liquid Chromatography of Methyl Esters (Withdrawn 2003) The use of the polyester liquid phase facilitates the separation of both the saturated and various unsaturated fatty acid methyl esters on the chromatogram obtained. www.astm.org /DATABASE.CART/REDLINE_PAGES/D1983.htm   (315 words)

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