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  • Gas chromatography  (280)
  • Springer  (280)
  • American Chemical Society
  • 2005-2009
  • 1985-1989  (172)
  • 1980-1984  (108)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 34 (1983), S. 20-26 
    ISSN: 1570-7458
    Keywords: Dioryctria abietella ; Cone pyralid ; Lepidoptera ; Pyralidae ; Sex pheromone, (Z,E)-9,11-tetradecadienyl acetate ; Single sensillum recordings ; Electroantennography ; Gas chromatography ; Mass spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé L'analyse en chromatographie gazeuse associée à une détection électroantennographique a montré que l'acétate (Z,E)-9,11-tétradécadiényle (Z,E)-9,11–14:Ac est l'un des composants de la phéromone de Dioryctria abietella Schiff (Lepid.: Pyralidae). Couplage chromatographie en phase gazeuse spectrometrie de masse a montré la présence d'acétate tétradécadiényle avec un spectre de masse et un indice de rétention identiques au Z,E-9,11–14:Ac Un récepteur cellulaire sensible à la fois au Z,E-9,11–14:Ac et à un extrait de la femelle a été identifié sous l'antenne du mâle. Les analyses des antennogrammes et de la cellule isolée ont étayé la caractérisation du composant de la phéromone comme étant Z,E-9,11–14:Ac. Un récepteur cellulaire additionnel sensible à l'acétate (Z.)-9-tétradécadiényle et à l'acétate (Z.E.)-9,12-tétradécadiényle a été trouvé sur l'antenne du mâle, mais il n'était pas activé par l'extrait de la femelle. Sur le terrain Z,E-9,11–14:Ac, présenté seul, attirait des nombres importants de mâles de D. abietella. L'addition de l'acétate (Z)-9-tétradécényle a inhibé l'attraction des mâles par les pièges.
    Notes: Summary Gas chromatographic analyses coupled with electro-antennographic detection indicated that (Z,E)-9,11-tetradecadienyl acetate (Z,E-9, 11–14:Ac) is a pheromone component of the cone pyralid Dioryctria abietella. Gas chromatographic-mass spectrometric analyses confirmed the presence of a tetradecadienyl acetate with mass spectrum and retention index identical to Z,E-9,11–14:Ac. A receptor cell sensitive to both Z,E-9,11–14:Ac and the female extract was identified on the male antenna. An additional receptor cell sensitive to (Z)-9-tetradecenyl acetate and (Z,E)-9,12-tetradecadienyl acetate was found on the male antenna but was not activated by the female extract. In the field Z,E-9,11–14:Ac presented alone attracted significant numbers of male D. abietella. Addition of (Z)-9-tetradecenyl acetate inhibited the attraction of males to traps.
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  • 2
    ISSN: 1432-1432
    Keywords: Primordial terrestrial atmospheres ; CH4, C2H2, CO2 ; Prebiotic synthesis ; High-frequency discharge ; Hydrocarbons ; Gas chromatography ; Mass Spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Various hydrocarbons were synthesized by high-frequency discharge in a primordial terrestrial model atmosphere. The products were extracted by benzene or methanol and analyzed by GC-MS. The mean carbon chain length of the hydrocarbons formed by the discharge through pure CH4 gas was less than 6. Benzene was also obtained. Some isomers were obtained for each of the hydrocarbons containing a given number of carbons. When a small amount of C2H2 was added to the CH4, longer chain compounds were formed, as compared with discharge in CH4 only. However, when the amount of C2H2 was increased, unextractable high molecular weight compounds were produced. The amounts of products decreased as the mixing ratio of CO2 to CH4 increased. No hydrocarbons were detected when the ratio of CO2/CH4 exceeded 1.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Trees 1 (1987), S. 94-101 
    ISSN: 1432-2285
    Keywords: Monoterpenes ; Abies alba Mill ; Resin ; Seeds ; Gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Using gas-chromatographic methods, the variability of the contents of monoterpene hydrocarbons (α-pinene, β-pinene, Δ3carene and limonene) in the resin of silver fir seeds (Abies alba Mill.) was studied. Resin cavities were characterized according to their position on the seed surface. It was estabilished that the terpene content of the resin of cavities localized on the abaxialadaxial surfaces of the seed differs significantly, creating a gradient of resin composition around the circumference of the seed. The differences between various resin cavities of single seeds were greater than the differences between different seeds of a single cone and between seeds of various cones on a single tree. An accurate definition of the resin cavity location on the seeds appears to be a fundamental condition for the collection of a sample representing the resin composition of individual trees. Resin biosynthesis in the course of organogenesis and the control of terpene contents in the resin of various locations on the seed and the cone are discussed.
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  • 4
    ISSN: 1432-0878
    Keywords: Preputial glands ; Nude mice ; Ultrastructure ; Gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The preputial glands of male nude (nu/nu) mice were analyzed by a combination of electron microscopy and gas chromatography to determine whether or not they are affected, like developing hairs and nails, by the nu/nu genotype. Results of the analyses revealed no differences between the glands of nude and normal male mice in either their ultrastructural characteristics or lipid secretory products.
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  • 5
    Electronic Resource
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    Springer
    Chromatographia 13 (1980), S. 203-206 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Carrier gas purity ; Sample stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The amount of oxygen which may be present in the gas volume corresponding to a peak is investigated and compared to the sample amounts. It is shown that even with high purity carrier gases one may have a significant excess of oxygen present at low sample amounts. Attention is drawn to the possibility of impurity build-up by diffusion e.g. through the septum.
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  • 6
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    Springer
    Chromatographia 13 (1980), S. 263-270 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Metal complexes ; Enantiomers ; Isotopic composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The high selectivity of complexation gas chromatography has been employed for enantiomer resolution and isotope separation. Thus, a chiral olefin, 3-methylcyclopentene, has been resolved analytically on optically active dicarbonyl-rhodium(I)-3-trifluoroacetyl-1R-camphorate in squalane. The deuterated ethylenes C2H4−nDn have been separated on the same rhodium(I)-containing stationary phase. The chiral aliphatic oxiranes epoxypropane andtrans-2,3-epoxybutane have been resolved on optically active nickel(II)-bis-3-trifluoroacetyl-1R-camphorate in squalane.
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  • 7
    ISSN: 1612-1112
    Keywords: Gas chromatography ; On-column abstraction ; Aliphatic aldehydes ; Amine antioxidants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The selective on-column abstraction of aliphatic aldehydes by gas chromatographic stationary phases containing N-iso-propyl N′-phenyl-p-phenylenediamine is described.
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  • 8
    Electronic Resource
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    Chromatographia 14 (1981), S. 19-22 
    ISSN: 1612-1112
    Keywords: Teflon columns ; Chemically modified teflon ; Gas chromatography ; Capillary columns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Wall-coated open tubular columns prepared from chemically modified teflon tubing have been developed for gas chromatography. Chemical reaction of the inner walls of teflon tubing allows bonding of an adhesive layer on which a variety of stationary phaes can be coated. Test mixtures of alkanes and alcohols were used to investigate the chromatographic properties of these columns and the stability and mixing of the adhesive and stationary phae layers. the results in dicate that mixing of the layers is negligible and that the column is stable for a long period of time.
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  • 9
    ISSN: 1612-1112
    Keywords: Teflon capillary columns ; Chemically modified teflon ; Gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The preparation of teflon capillary columns employing direct coating of the stationary phase to the chemically modified teflon surface and the role of the chemically modified teflon in the separation mechanism are described. Two types of contributions from the modified teflon have been observed: nonspecific adsorption of the carbon surface and specific interactions of polar groups in the carbon skeleton. The use of polar liquid phases can eliminate adsorption due to the presence of polar groups in the modified teflon.
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  • 10
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    Chromatographia 14 (1981), S. 55-66 
    ISSN: 1612-1112
    Keywords: Capillary columns, glass ; Gas chromatography ; Column preparation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Kapillar-Gas-Chromatographie ist heute das sich am stärksten entwickelnde Gebiet der Gas-Chromatographie. Es gibt viele komplexe, neue Fragestellungen in der Analytik, welche den Einsatz spezieller Kapillarsäulen erfordem. Glücklicherweise gibt es aber auch eine große Zahl von Herstellungsverfahren für Kapillarsäulen, welche — noch mehr als bei der Herstellung von gepackten Säulen — eine Anpassung an die gestellten Aufgaben ermöglichen. In diesem Artikel werden die Herstellungsverfahren für Kapillarsäulen zusammengestellt und Anregungen gegeben, wie aufgaben-orientierte Säulen erreicht werden.
    Notes: Summary Glass capillary column chromatography is the most rapidly growing part of gas chromatography. There are many complex new analytical tasks and they require special capillary columns, Fortunately there is a wide range of column preparation methods available, and they make the preparation of glass capillary columns a more varied job than that of packed columns. In this paper these methods are reviewed and suggestions are given for making task-oriented columns.
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  • 11
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Urea herbicides ; Catalytic hydrolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the rapid catalytic hydrolysis of phenylurea herbicides on silica gel at elevated temperatures. After derivatisation of the anilines produced with heptafluorobutyric acid anhydride final analysis is done on a gas chromatograph equipped with an electroncapture detector. Detection limits are in the 1–5 picogram range. The method has successfully been applied to residue analysis of water samples at the 1 ppb level. The determination of free anilines present in water samples and the potential of various techniques to be used to discriminate between free anilines and parent herbicides are also discussed.
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  • 12
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Graphitised carbon black ; Phenols ; Water pllutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The fractionation of eleven phenols which may be contaminants in drinking water has been accomplished by using acid-washed graphitised carbon black modified with trimesic acid and PEG 20 M.
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  • 13
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    Springer
    Chromatographia 14 (1981), S. 447-451 
    ISSN: 1612-1112
    Keywords: Headspace analysis ; Gas chromatography ; Residual analysis of polyethylene terephthalate ; Acetylene reduction assay ; Ethylene evolution in germinating seed ; Acetaldehyde generation in polyester resin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary New application areas for headspace gas chromatography in agricultural and polymer degradation research are described. Specific examples are drawn from the various forms of headspace analysis with emphasis on the automated static equilibrium method.
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  • 14
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    Chromatographia 13 (1980), S. 35-39 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Nitromethane ; Nitroalkanes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Impurities in commercially available nitromethane have been determined by gas-liquid chromatography using six different column packings. Besides nitromethane, 1-nitropropane, 2-nitropropane, acetonitrile, methanol, small amounts of ethanol and acetaldehyde have been detected. The presence of formaldehyde, ethyl acetate and acetone is probable. Mixtures containing comparable amounts of the four nitroalkanes could be separated on all columns, but plots of logarithms of the retention times vs. carbon number or boiling points of the nitroalkanes or column temperatures were linear only in case of columns packed with Porapak R and Q.
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  • 15
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    Chromatographia 16 (1982), S. 60-62 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Amines ; Derivatization ; Chloroformate esters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The gas chromatographic analysis of amines after conversion to electron capture sensitive carbamates in two-phase systems has been studied. Hydrophilic compounds, for instance methylamine, are reacted with 2,2,2-trichloro-tert. butyl chloroformate. Quantitation below 10−7 M can be made by thermionic or electron capture detection. A hydrophobic amine, namely N,N-dimethyl-n-octylamine, was derivatized with 2,4,6-tribromophenyl chloroformate with addition of iodide ion to the aqueous phase. The favorable effect of iodide ion as well as the choice of pH and chloroformate ester is discussed.
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  • 16
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    Chromatographia 16 (1982), S. 98-102 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Rectangular channel ; Efficiency ; Capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Gas chromatographic experiments have been performed in a truly rectangular channel with a 60∶1 cross-sectional aspect ratio, constructed according to the field-flow fractionation technology. It is shown that the peak broadening is controlled by the thickness of the channel while the maximum load is determined by the largest cross-sectional dimension. However, even with its elongated configuration, the side walls contribute significantly to the band broadening of solutes with a high diffusivity. Good agreement is found between the experimental plate height data and the recent theoretical calculations of Golay [13] taking into account the side-wall effect.
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  • 17
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Stationary liquid, choice of ; Physico-chemical data
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A table of data for acidity, basicity, polarity and London potential for stationary phases is given. These provide guidance in choosing a stationary phase for a given task from the 26 substances listed. The indices are calculated from infra-red shifts of 1-chlorobutane and the visible wavelength shifts of l2 when they are dissolved in the stationary phases, from NMR estimates of acidity and basicity and from relative retention data. They replace the less reliable data of Burns and Hawkes. Methods of determining the indices are suggested that require only a gas chromatograph and can be applied by technicians with no specialized understanding of solution parameters. An attempt to add electron donoracceptor indices to the table was unsuccessful. A further table is given of the slopes of the log plots d(logt′)/dC for use in extrapolating from one homologue to another on these stationary phases.
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  • 18
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    Chromatographia 20 (1985), S. 343-346 
    ISSN: 1612-1112
    Keywords: Thermosorb ; Tenax GC ; Environmental Analysis ; Trace Organics ; Gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A preliminary study has been carried out to evaluate a new adsorbent, Thermosorb, for trace level organic contaminants. For this purpose, a comparison was made with a well-characterized adsorbent, Tenax GC, using a prepared aqueous solution of trace organic components. In addition, a comparison was made of chromatograms of air contaminants obtained using both of these adsorbents, under equivalent conditions. The results clearly indicated the potential of this thermally stable, inorganic adsorbent for many trace organic substances of environmental interest.
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  • 19
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    Chromatographia 20 (1985), S. 371-375 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Flame photometric detector ; Sulphur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of experimental conditions such as gas flow rates, detector and column temperatures on sulphur response are discussed. It is concluded that the response of the flame photometric detector is affected by the O/H ratio and the total gas flow. Column temperature has an important influence upon S2 emission. It is shown that the sulphur response of the FPD is dependent on the compound containing the sulphur.
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  • 20
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    Chromatographia 17 (1983), S. 269-284 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Liquid chromatography ; Phenols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Gas and high-performance liquid chromatographic methods in the analysis of phenols are reviewed. Among the great number of phenolic compounds analyzed, alkylphenols, chlorophenols, dihydroxy- and trihydroxybenzenes and biphenols are chiefly considered. The advantages and drawbacks of the methods are discussed, quoting the most important work. Relationships between the structural characteristics of phenols, the stationary phase structure, the mobile phase composition and the retention data are treated. Typical examples of the conditions for GC and HPLC analysis are summarized in tables. The literature comprises over 270 references, most of them recent.
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  • 21
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Average molecular polarizability ; Retention index ; Polycyclic aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The Kováts retention indices of 10 polycyclic aromatic hydrocarbons were determined on SE-30, OV-101, SE-52, OV-7 and OV-17 stationary phases. A significant correlation has been found between the retention indices and the average molecular polarizabilities of the analyzed substances. Equations were derived for the direct determination of the average molecular polarizabilities from the retention index values. The influence of the temperature on this relationship is also indicated.
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  • 22
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Flame ionisation detection ; Cyanogen ; Cyanogen chloride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The response of a flame ionisation detector (FID) to cyanogen ((CN)2) and cyanogen chloride (CNCI) has been studied. The lower limits of detection for (CN)2 and CNCl were 6×10−12 moles and 2×10−11 moles respectively. In a comparative study a thermal conductivity detector gave as its lower limit of detection for both (CN)2 and CNCl 4×10−11 moles. Both detectors showed excellent linearity over the range 0 to 10 micromoles. The ratio of the gradients of the FID calibrations (CN)2/CNCI were found to be approximately two suggesting the response depended on the cyanide group. The response and stability of the FID was investigated as a function of air and hydrogen flow-rates. The response increased with increasing air flow-rate for both (CN)2 and CNCI up to 300cm3min−1, thereafter no significant increase was observed. On raising the hydrogen flow from 10 to 25cm3min−1 only a slight increase in the sensitivity of the FID towards both (CN)2 and CNCI was observed. At higher flow rates the response for (CN)2 increased markedly whereas at the same flow rates the response for CNCI increased only slightly.
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  • 23
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    Chromatographia 21 (1986), S. 214-218 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Behaviour of metal acetylacetonates ; Adsorption isotherms ; Heat of solution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Specific retention volumes, adsorption isotherms, molar heats of solution and changes of the entropy were determined from chromatographic data, which was obtained by the gas chromatographic separation of metal acetylacetonates. The retention data for Cr(III), Co(III) and Al(III) acetylacetonates were measured at different temperatures and different flow rates. From the retention data other values associated with adsorption and solution phenomena were calculated.
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  • 24
    ISSN: 1612-1112
    Keywords: Esterification in aqueous solution ; iso butyl esters of C1–C20 fatty acids ; Gas chromatography ; Fatty acid analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary C1–C20 carboxylic acids have been esterified in aqueous solutions with i-butanol. Gas chromatographic analyses have been performed from a single chromatogram. It has been established that esterification in the concentration range of [H2O]/[i-BuOH]=0.01–10.3 can be utilized for the quantitative determination of these carboxylic acids. The presence of water does not interfere in the range of [H2O]/[i-BuOH]=0.01–1.03. In the cases of [H2O]/[i-BuOH]〉1.03, anhydrous sodium sulfate has been used for binding the water, in an amount of [Na2SO4]anh./[H2O]≥0.2.
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  • 25
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Capillary columns ; Immobilized stationary phase ; Carbowax-type stationary phase ; Cross-linked polyurethane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The preparation of an immobilized stationary phase based on Carbowax 20M is described. The stationary phase cross-linking was carried out with Desmodur N 75 or Desmodur L 75, pluriisocyanates. The properties of the prepared stationary phases are compared.
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  • 26
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Esterification in aqueous solution ; n-Butyl esters of C2−C16 dicarboxylic acids ; Dicarboxylic acid analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary C2−C16 dicarboxylic acids were esterified in aqueous solution in the presence of sulfuric acid. Esterification in water/n-butanol mixtures with mole ratios between 0.02 and 2.53 can be utilized for the quantitative determination of the dicarboxylic acids by gas chromatography. The presence of water does not interfere at water/n-butanol mole ratios below 0.27. For mole ratios above 0.27 anhydrous sodium sulfate has been used for binding the water. The mole ratio range was 0.25–0.75 for anhydrous sodium sulfate/water, and 0.32–1.3 for sulfuric acid/anhydrous sodium sulfate.
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  • 27
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    Chromatographia 18 (1984), S. 663-667 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Gas solubilities ; Enthalpies of solution ; Polar solutions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The gas-liquid chromatographic method has been used to determine the solubilities and partial molar enthalpies of solution of the gases H2S, CO2 and COS in four polar solvents. The results agree well with literature values obtained using conventional techniques, with the one exception of H2S in N-methyl-2-pyrrolidinone. In this case there is some evidence for the occurrence of adsorption at the gas-liquid interface.
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  • 28
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Esterification in aqueous solution ; n-Butyl esters of aromatic polycarboxylic acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The direct esterification and gas chromatographic analysis of aromatic carboxylic acids as n-butyl esters is described. Derivatization is performed in aqueous solution with n-butanol in the presence of sulfuric acid. The butyl esters of benzoic, phthalic, hemimellitic, trimellitic, trimesic and pyromellitic acids permit their gas chromatographic separation from each other and from fatty acids and alipatic dicarboxylic acids. At mole ratios of [H2O]/ [n-BuOH]≤0.04 the water present does not interfere with the esterification reaction. At mole ratios above 0.04 anhydrous sodium sulfate is used for binding the water, at mole ratios of [Na2SO4 anh.]/[H2O]=0.25–0.75.
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  • 29
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Volatile nitrosamines ; Fused silica capillary columns ; Linear indices
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Fused silica capillary columns of different diameters and polarities are linked to a thermal energy analyzer and a flame ionisation detector for comparison. Extra column effects are discussed. Unsymmetrical homologue nitrosamines are applied in order to assign the volatile nitrosamines most often to be determined by their linear indices rather than by their overall retention times.
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  • 30
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Thermionic detector ; Flame-forming agents ; CO2 and water gas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of carbon monoxide were suggested as the flame-forming agent in the thermionic detector (TID). The main characteristics of this detector were studied. It was shown that the optimum flow rate of carbon monoxide is 40 ml/min at an air flow rate of 400–550 ml/min. The response increases twice with the positive potential on the collector. Molar responses of TID were compared with those obtained when using carbon monoxide and hydrogen. For instance, for phosphorus containing compounds they are approximately the same (∼102), while for nitrogen containing compounds in the case of carbon monoxide, there is a 2–5 fold increase in the response. The linear dynamic range for methaphose and azobenzene is 103.
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  • 31
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Metal complexes ; Chemically bonded phase ; Specific interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Packings consisting of chemically bonded diphenylphosphine complexes with CuCl2 and CuBr2 were synthesized and their retention parameters determined. The packings investigated are capable of specific interactions with electron-donating compounds and are characterized by particularly high selectivity in relation to cis and trans isomers allowing their complete separation.
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  • 32
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    Chromatographia 23 (1987), S. 818-824 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Selective sampling ; On-line fractionation ; Essential oil analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The paper describes the possibilities of on-line selective sampling as an on-line fraction technique for the analysis of essential oils. Selective sampling is a micro-separation method, on-line with on-column injection, carried out directly in the syringe body by means of a selective elution of the sample through a fraction cartridge. The paper reports a method of both preparing and standardizing silica gel cartridges, and illustrates through some examples the results of some elution series of solvents on different essential oils.
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  • 33
    ISSN: 1612-1112
    Keywords: Organic pollutants determination ; Gas chromatography ; Thermal desorption
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    Topics: Chemistry and Pharmacology
    Notes: Summary The problem of the separation of 34 volatile organic chlorinated compounds is solved by using three different GC columns selected according to the needs of the particular separation required. The effect of water vapor contained as moisture in the trapped air on the retention of some characteristic compounds is studied. The influence of dead volumes on trap injection is also studied.
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  • 34
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    Chromatographia 23 (1987), S. 888-892 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Calculation of temperature programmed ; Retention indices
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    Topics: Chemistry and Pharmacology
    Notes: Summary A new method is presented for the calculation of the retention indices under linear temperature programming with or without an initial isothermal period. The data calculated by the method are in good agreement with the isothermal retention indices.
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  • 35
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Esterification in aqueous solution ; n-Propyl esters of aromatic polycarboxylic acids
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    Topics: Chemistry and Pharmacology
    Notes: Summary The direct esterification and gas chromatographic analysis of aromatic carboxylic acids as n-propyl esters is described. Derivatization is performed in aqueous solution with n-propanol in the presence of sulfuric acid. The n-propyl esters of benzoic, phthalic, trimellitic and pyromellitic acids permit their gas chromatographic separation from each other and from fatty acids and aliphatic dicarboxylic acids. At mode ratios of [H2O]/[n-PrOH]≤0.03 the water present does not interfere with the esterification reaction. At mole ratios above 0.03 anhydrous sodium sulfate is used for binding the water, at mole ratios of [Na2SO4anh.]/[H2O]=0.51–1.52 and of [H2SO4]/[Na2SO4anh.]=0.43–1.28, respectively.
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  • 36
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Micropacked columns ; Quantitation ; Fermentation products
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    Topics: Chemistry and Pharmacology
    Notes: Summary A new method is proposed for the analysis by gas chromatography of volatile compounds found in alcoholic and acetic fermentation samples. The method represents a suitable choice for the accurate and precise determination of 19 compounds (including Methanol) by direct injection onto a single column. Chromatograms of synthetic mixtures as well as actual samples show the capabilities of the micropacked column used.
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  • 37
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    Chromatographia 18 (1984), S. 202-204 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Polysiloxane stationary phases ; Heat of adsorption ; Heat of solution
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    Topics: Chemistry and Pharmacology
    Notes: Summary The changes in the heat of solution of polar compounds and xylene isomers in methylsilicone fluid OV-101 deposited on Chromosorb W AW DMCS were studied. It was shown that the heat of solution increases with an increase of the percentage loading of the OV-101 up to 10%. Solution and adsorption thermodynamic characteristics of the studied system are briefly discussed.
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  • 38
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Metal complexes ; Chemically bonded phase
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    Topics: Chemistry and Pharmacology
    Notes: Summary Packings consisting of diphenylphosphine complexes with CoCl2 and CoBr2, chemically bonded to the silica surface, were synthesized and their retention parameters determined. The packings are capable of specifically interacting with electron-donating compounds by forming π-complexes. The interaction is considerably stronger in the case of CoBr2-containing packing than in the case of CoCl2-containing packing.
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  • 39
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    Chromatographia 18 (1984), S. 234-238 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Open-tubular columns ; On-column injection ; Stopped-flow operation
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    Topics: Chemistry and Pharmacology
    Notes: Summary A simple, inexpensive, on-column injector of the septum moving-needle kind is described for quantitative analysis using open-tubular columsn. when operated in the stopped-flow mode an improvement incolumn efficiency is observed combined wit a diminished tendency to produce split-top peaks, particularly for late eluting peaks. Using electronic integration a relative error of about 2.7% was observed for peaks spanning a wide range of sample concentrations and volatilities.
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  • 40
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    Chromatographia 18 (1984), S. 243-248 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Carrier gas ; Viscosity ; Influence of temperature
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The vicosity-temperature relationship of the three gases (helium, nitrogen and hydrogen) most frequenly used as the carrier gas in gas chromatography is studied. Based on available data, equaitions are derived to describe this relationship. Using these equations viscosity data are tabulated for the chromatographically important temperature range.
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  • 41
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    Chromatographia 18 (1984), S. 260-264 
    ISSN: 1612-1112
    Keywords: Parabens and their dissolution ; Pharmaceutical dosage forms ; Derivatization ; Gas chromatography
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    Topics: Chemistry and Pharmacology
    Notes: Summary A specific, sensitive and general applicabla gas chromatographic method is described for the determination of parabens in various liquid pharmaceutical preparations: propylparaben and butylparaben in a liquid antacid dosage form (I); methylparaben, ethylparaben and propylparaben in a syrup (II); methylparaben and propylparaben in a solution for injection (III). Each time one of the parabens is used as internal standard. The parabens are extracted with diethylether and derivatized by silylation. Different columns are used for the analysis of the parabens: 3% SE-30 column, a 3% QF-1 column for different selectivity, a 2% OV-1 column for isothermal operation. Special attention is attributed to the standard: the parabens are dissolved in a minimal amount of 0.1 M sodium hydroxide and extracted in the same way as the pharmaceutical dosage form.
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  • 42
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Configuration ; Resolution ; Alcohols
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    Topics: Chemistry and Pharmacology
    Notes: Summary The study of the resolution of sixteen secondary aliphatic alcohols by gas chromatography on (+)-dodecyl (2R, 3R)-tartrate, trapping the ascending part of the peak from a conventional filled column, has allowed the determination in a single operation of the sign and order of emergence of enantiomers. A correlation between the configuration of these secondary alcohols and their order of emergence has been established.
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  • 43
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    Chromatographia 18 (1984), S. 309-312 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Carboxylic acids ; Acetonyl derivatives
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    Topics: Chemistry and Pharmacology
    Notes: Summary The preparation of the acetonyl esters of nine aliphatic carboxylic acids is described, the general formula of the derivatives being RCOOCH2COCH3 where R=alkyl or H. The derivatives show good chromatographic properties on both packed and capillary columns. The electron impact and chemical ionisation mass spectra of the derivatives are discussed.
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  • 44
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    Chromatographia 23 (1987), S. 195-198 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Structure-retention relationships ; Polarity parameters ; Retention index
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    Topics: Chemistry and Pharmacology
    Notes: Summary The possibility of evaluation of the parameters representing the dispersive solute-solvent interactions is presented. BN and Bs values can be used to describe the liquid phase polarity and to predict the retention indices of alcohols when the model polyxyethylene glycol dialkyl ethers and their sulphur analogs are used as stationary phases. The possibility of the first ionization potentials estimation is also presented.
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  • 45
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Thermodynamic relationships ; Retention index ; Peak identification
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    Topics: Chemistry and Pharmacology
    Notes: Summary A thermodynamic criterion, ΔQ, is suggested which permits to estimate the difference in the functional group energy of interactions for two different stationary phases. The linear dependence of ΔQ on the homolog number m of any series Rm X can be used as the thermodynamic criterion for the identification of substances by GC analysis.
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  • 46
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    Chromatographia 18 (1984), S. 477-488 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Open tubular (capillary) columns ; Sample capacity ; Column comparison ; Film thickness ; Column diameter
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    Topics: Chemistry and Pharmacology
    Notes: Summary Wall-coated, open-tubular (capillary) columns prepared from different diameter tubing, with different liquid phase film thickness, are compared with each other and with packed and support-coated open-tubular columns. The comparison is based on the variation of the phase ratio and the capacity factor, and includes column efficiency (HETP, theoretical plate number), resolution, retention time, and sample capacity. Problems associated with the evaluation of the sample capacity are outlined. The influence of temperature on column performance is discussed in detail. Finally, the possibilities of short, wide-bore open-tubular columns prepared with a thick liquid-phase film are demonstrated.
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  • 47
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Prediction of retention volume ; Porous polymers coated with liquid phases
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    Topics: Chemistry and Pharmacology
    Notes: Summary A new expression which permits the prediction of the net retention volumes in gas chromatography with column packings of coated porous polymers is reported. The porous polymers Chromosorb 101 and Chromosorb 102 were used as supports and squalane, Ethofat and Carbowax 20M as stationary phases at three different column temperatures of 80°C, 100°C and 150°C. Several organic compounds of various polarity were used as test compounds and the net retention volumes, VNtheor, have been calculated according to this new expression. The VNtheor values were compared with the experimental net retention volumes, VNexp, and it was found that the difference between these two values is dependent on the type of compound and column packing. Nevertheless, the elution order could be predicted in most cases.
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  • 48
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    Chromatographia 23 (1987), S. 499-501 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Packed+capillary GC switching system ; Precolumn construction, oven and connector
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    Topics: Chemistry and Pharmacology
    Notes: Summary The constractional details of precolumns, its oven and connector have been given with two types of multiflow control modules. Two types of phases made in China, a silanized pellicular beads and a non silanized pellicular silica beads, with an optimum particle size of 20μm to 30μm were packed in the precolumn 20mm in length with the column efficiency of 4620 plates/meter at column temperature of 49°C. A 25m×0.22mm i.d. capillary column coated with bonded methylsilicone phase from Chrompack connected with the precolumn (250°C) has an efficiency of 5376 plates/meter for n-octane. But it decreased to 3149 plates/meter by decreasing the precolumn temperature to 130°C.
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  • 49
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Capillary columns ; Immobilized Carbowax-type stationary phases ; Free fatty acids analysis
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    Topics: Chemistry and Pharmacology
    Notes: Summary Capillary columns coated with acid-modified poly-(ethylene glycol)-type immobilized stationary phases have been studied. The thermostability and chromatographic behaviour of the columns and the stability of the coated films after washing with different solvents were investigated.
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  • 50
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Fourier transform IR detection ; Headspace sampling ; Solvents of abuse
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    Topics: Chemistry and Pharmacology
    Notes: Summary After experimental intoxication of rats, gas chromatography — Fourier transform infrared spectrometry with headspace sampling (HS/GC/FT-IR) was used to identify solvents of abuse in biological material (blood, liver, lungs and brain). Limits of detection were measured for acetone, 2-butanone, ether, toluene and trichlorethylene with standard solutions. All the solvents have been identified in the organs of the intoxicated rats. For blood samples a salting-out effect was obtained with potassium carbonate. HS/GC/FT-IR allowed the identification of metabolites of acetone (isopropanol) and of 2-butanone (2-butanol) in blood and organs.
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  • 51
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Simultaneous distillation-extraction ; Cheese volatiles
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    Topics: Chemistry and Pharmacology
    Notes: Summary A simultaneous distillation-extraction apparatus proposed by Godefroot has been used for the GC study of volatile components of cheese. 5–10 g of cheese provide a fraction that can be directly injected into a GC or a GC/MS. Two capillary columns (SE-30 and SP-1000) were evaluated, the second one being adequate for quantitative determinations. Camphor was used as internal standard. The coefficients of variation ranged from 1.4 to 11.8. The technique can be used as a fast method for the characterization of cheeses from their volatile component concentrations.
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  • 52
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    Chromatographia 25 (1988), S. 1087-1088 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Log plot ; Homologous series
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    Topics: Chemistry and Pharmacology
    Notes: Summary The slope of the log plot of the adjusted retention time of a homologous series usually varies from that of the n-alkane series by no more than 2%, though with unusual interactions between the functional group and the stationary phase the difference may be as high as 7%.
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  • 53
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Preparative scale separations ; Plate model
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    Topics: Chemistry and Pharmacology
    Notes: Summary Two close-boiling materials, diethyl ether (DEE) and dichloromethane (DCM), were separated to investigate the effects of the pure components and the mixture on elution in preparative gas-liquid chromatography. Nitrogen was used as the carrier gas, and the chromatographic column (1 cm I.D. and 0.75m length) was packed with Chromosorb A with different quantities of dinonyl phthalate stationary phase and particle sizes. Below ca. 7% (by wt.) of feed concentration, the experimental elution curves of pure DEE and DCM were almost the same as those of the mixture, and the theoretical plate model can be used successfully to predict the elution curves.
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  • 54
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    Chromatographia 25 (1988), S. 404-408 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Silica surface modification ; Hexamethylcyclotrisilazane ; Hexamethyldisilazane ; Support materials
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    Topics: Chemistry and Pharmacology
    Notes: Summary The paper is concerned with the structure of an organic layer bonded to the silica surface modified with silazanes. The changes of the retention volumes of hydrocarbons is studied for the silicas modified with hexamethylcyclotrisilazane, hexamethyldisilazane and their mixtures. It is shown that most of the carbon in the layer after hexamethylcyclotrisilazane modification is bonded to the surface by Si−O−Si bonds. This fact supports the assumption of a fragmentation of the cyclosilane used for modification.
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  • 55
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Statistical criteria ; Non-linear models ; Constants for n-alkane retention curve ; Multiparametric least-squares adjustment
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    Topics: Chemistry and Pharmacology
    Notes: Summary Multiparametric, least-squares, regression treatment of G.C. data is extended to describe deviations from the usual linear model. Through statistical evaluation of results, four parameters models are generally found adequate and the use of higher degree empirical models is discouraged.
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  • 56
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    Chromatographia 25 (1988), S. 539-542 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Temperature programming ; Retention index
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    Topics: Chemistry and Pharmacology
    Notes: Summary A method is presented for the calculation of retention indices at an assigned temperature from temperature-programmed data. If the retention times at two different program rates for the solutes and the n-alkanes are known, the retention indices at an assigned temperature can be calculated directly.
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  • 57
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    Chromatographia 22 (1986), S. 183-186 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; C2−C5 hydrocarbons ; Pre-Concentration on silica gel ; Sorption efficiency
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    Topics: Chemistry and Pharmacology
    Notes: Summary A short stainless steel column packed with silica gel is cooled to −78°C and atmospheric hydrocarbons are preconcentrated from 3 I of air on it. Desorption to the analytical column is by heating for 10 min to 200°C. Analysis is by GC on OPN-Poracil C at 27°C. The sorption efficiencies were nearly 100% for most of the light hydrocarbons.
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  • 58
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    Chromatographia 26 (1988), S. 125-132 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Non-equilibrium frontal chromatography ; Nonlinear isotherms ; Variable velocity ; Multicomponent mixtures
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    Topics: Chemistry and Pharmacology
    Notes: Summary The paper presents a classification of various theoretical models for multicomponent gas chromatography at u=var for high concentrations of the mixture components with consideration of the major distinctive features of the interphase mass exchange inside the porous grains of the adsorbent and outside them within the porous medium of the chromatographic column. It has been shown that the conditions determining a given front behaviour of multicomponent gas mixture at u=var depend on: theoretical models for the kinetics and dynamics of adsorption; the values of mass exchange parameters inside the porous grains and in the porous medium. Formulae have been derived for calculating the values of the quantities characterising the frontal behaviour in the stage of adsorption and desorption of multicomponent mixture at u=var.
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  • 59
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Physico-chemical properties ; Retention indices ; Cycloolefins
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    Topics: Chemistry and Pharmacology
    Notes: Summary The retention indices of mono and polycycloolefins with endo or exo double bonds, on squalane or polypropylenglycol 425 are related to their physico-chemical properties such as boiling point, molar volume, molar refraction, and refractive index. Equations have been empirically obtained, from which accurate retention indices of these compounds can be predicted. Unknown boiling points of some of these compounds can also be calculated from their lineal relation with the retention index on squalane.
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    Chromatographia 23 (1987), S. 839-843 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Stationary phases ; Porous polymer beads ; Polarity ; Adsorbents ; Breakthrough volume
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    Topics: Chemistry and Pharmacology
    Notes: Summary The breakthrough volume of ådsorbent traps made with porous polymer beads Porapak N, P. Q, R, S was evaluated by analysis of polarity reference substances proposed by Rohrschneider (ethanol, methyl ethyl ketone, nitrometane, benzene, pyridine) by McReynolds (butanol, methyl propyl ketone) and of the first term of some homologous series: alcohols, aldehides, carboxilic acids, nitrocompounds, iodoalkanes and nitriles. Adjusted retention times of the compounds were measured at 200°C and correlated with the physical properties and with polarity class according to Ewell. Trapping efficiency of the various Porapak types was evaluated and the theoretical breakthrough volumes at 25°C was calculated for the used test substances.
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    Chromatographia 23 (1987), S. 850-855 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Capillary columns ; Bacterial cellular fatty acids ; Stationary phase selectivity ; Solid phase preseparation
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    Topics: Chemistry and Pharmacology
    Notes: Summary The importance of selectivity in the capillary gas chromatographic analysis of the cellular fatty acids of micro-organisms is underestimated. The analysis on apolar silicone phases can lead to erratic elucidation of the fatty acid structure. Qualitative errors have been detected in commercially available standards on which computer matching identification techniques are based. Using highly polar capillary columns of the cyanopropyl silicone type, the errors could be elucidated. The exact identification of the hydrolysis products of bacteria is a must for chemotaxonomic studies applying chromatographic techniques. The fatty acid methyl ester profiles can also contain other chemical components which are very important taxonomic markers. Fatty aldehydes, for example, are main components in someClostridium species. Fractionation techniques are described for selective enrichment of fatty aldehydes and hydroxy fatty acids.
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    Chromatographia 27 (1989), S. 37-43 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Methylbromide ; Charcoal tubes ; Pollution
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    Topics: Chemistry and Pharmacology
    Notes: Summary Air sampling of methylbromide using 900 mg HBr-treated activated charcoal tubes, followed by solvent desorption and FID or ECD chromatographic analysis, makes it possible to evaluate concentrations ranging from 0.2 ppm (1 mg×m−3) to 250 ppm (1g×m−3) at ambient temperature even with a high hygrometric level. Thermal desorption does not lead to satisfactory results.
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    Chromatographia 27 (1989), S. 60-66 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Mass loadability ; Stationary phase capacity ; Capillary columns
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    Topics: Chemistry and Pharmacology
    Notes: Summary In GLC the mass load can be normalized with respect to the amount of stationary phase in one plate. This quantity can be used for a specified solute-liquid phase combination in any capillary or packed column, irrespective of the column dimensions or the number of plates. For each individual solute in a given stationary phase a unique factor β″ can be found, which accounts for the specific shape of the isotherm of this particular combination. this factor β″ corresponds well with the activity coefficients of the solutes in the stationary phase, by which a fairly good approximation of the mass loadability of the column at hand can be made without need for experiment.
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    Chromatographia 23 (1987), S. 215-219 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Liquid chromatography ; Thermodynamic equilibria ; Solution and adsorption thermodynamics ; Gas adsorption isotherms
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    Topics: Chemistry and Pharmacology
    Notes: Summary After a brief recall of the chromatographic principles, the different applications of gas chromatographic measurements of thermodynamic equilibria were reviewed. Gas and liquid chromatographies are now well known and elegant methods for measuring the physicochemical properties and phase equilibrium thermodynamic constants. Although fundamentally a dynamical method and mostly known as a powerful separation technique, chromatography can be schematized by a sucession of equilbria of a chemical species partitioning between a mobile phase and a fixed liquid or solid stationary phase. It can be operated in either infinite dilution or finite concentration conditions and permits to collect a large number of data for calculating molecular interactions for solutes which are either rare or available at the trace level. Gas chromatography permits the measurement of gas adsorption isotherm, gas-liquid equilibria, molecular diffusion and interaction virials. The modelization of successive partition equuilibria occuring in the chromatographic column leads to rather simple expression of differential enthalpy, entropy, free energy of adsorption or solution, variation of heat capacity, complexation constant, second virial coefficients, gas-solid and gasliquid isotherm and also binary or ternary equilibria. The possibilities of High Performance-Liquid Chromatography to investigate adsorption from solutions and chemical equilibria are also discussed.
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    Chromatographia 13 (1980), S. 686-692 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Micropacked columns in GC ; Microparticles
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    Topics: Chemistry and Pharmacology
    Notes: Summary Porous silica microparticles designed for modern liquid chromatography have proven effective in gas chromatography. Columns of 35–50 cm gave plate heights as low as 3.3 particle diameters and speeds of 2400 theoretical plates per second or 500 effective theoretical plates per second. Inlet pressures up to 70 atmospheres were required using hydrogen as carrier gas. The particles as received were too retentive for fast chromatography and gave asymmetric peaks. A coating of fluorosilicone oil overcame both problems. Other coatings were less effective. Bonded phases proved less satisfactory on both counts and also gave substantially less efficient columns and greater flow resistance. Column efficiency and flow resistance were sharply dependent on physical properties of the particles. The most efficient packing was clearly spherical particles of 5–10 μm diameter with narrow size distribution, pore diamters about 50 nm, BET surface areas of 25–50 m2/g and surfaces modified with trifluoropropyl silicone. A six-component hydrocarbon sample was separated in 33 s with a resolution of 4 for the most difficult pair and in 2.6 s with a minimal resolution. Performance was limited by end effects and by available pressure so that much better performance can be expected from longer columns and higher pressures.
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    Chromatographia 13 (1980), S. 752-754 
    ISSN: 1612-1112
    Keywords: Xylenol isomers ; Gas chromatography ; Polyols and polyethers as stationary phase ; Hydrogen bonding
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    Topics: Chemistry and Pharmacology
    Notes: Summary Xylenol isomers can be resolved on most polyols (sugars or sugar alcohols) and polyethers (polyethylene glycol or polypropylene glycol) with hydrogen-bonding interaction. They are separated on vinical polyols which have more hydroxy hydrogen than tetrol, and even on vicinal triol when its hydroxy hydrogen is acidic (stronger proton donor). The stronger is the hydrogen bonding interaction between xylenols and the liquid phase, the better is the separation of 2,4- and 2,5-xylenol, and the poorer the separation of 2,4-and 2,3-xylenol.
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    Chromatographia 13 (1980), S. 651-660 
    ISSN: 1612-1112
    Keywords: Capillary columns, glass ; Gas chromatography ; Column preparation
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    Topics: Chemistry and Pharmacology
    Notes: Summary Glass capillary column chromatography is the most rapidly growing part of gas chromatography. There are many complex new analytical tasks and they require special capillary columns. Fortunately there is a wide range of column preparation methods available, and they make the preparation of glass capillary columns a more varied job than that of packed columns. In this paper these methods are reviewed and suggestions are given for making task-oriented columns.
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    Chromatographia 13 (1980), S. 73-84 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Gas hold-up time ; Dead time
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    Topics: Chemistry and Pharmacology
    Notes: Summary The two approaches used for the calculation of the gas hold-up time and thus, the adjusted retention time are outlined, first for the restricted case when the carbon numbers of the three homologues used for the calculation are evenly spaced (c3−c2=c2−c1) and then, for the general case when (c3−c2) differs from (c2−c1). The basic difference in the philosophy of the two approaches is shown.
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  • 69
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    Chromatographia 14 (1981), S. 576-578 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Tortuosity factor
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    Topics: Chemistry and Pharmacology
    Notes: Summary The relationship between the obstructive factor γ and velocity was restudied. The dependence of the obstructive factor on velocity was verified. The effects of diffusion coefficient and particle-to-column diameter ratio on the obstructive factor-velocity relationship were investigated. The results are consistent with Hawkes' hypothesis that values of γ at low velocities are averages over tightly packed and loosely packed domains while at high velocities they are weighted in favour of the loosely packed domains where there is more flow.
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  • 70
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    Chromatographia 14 (1981), S. 648-652 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Gas-liquid adsorption ; Bulk solution ; Mixed stationary phases
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    Topics: Chemistry and Pharmacology
    Notes: Summary It is shown that the blending of some retention effects can make the resolution of complex mixtures on short classical columns as effective as on capillary columns.
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  • 71
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    Chromatographia 14 (1981), S. 699-703 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Headspace analysis ; Aromatic hydrocarbons ; Water analyses
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    Topics: Chemistry and Pharmacology
    Notes: Summary The possibilities of using headspace analysis of aromatic hydrocarbon traces in aqueous solutions with changing values of the partition coefficients are discussed. A variant of headspace analysis of the simplest aromatic hydrocarbon in natural and waste water is described. It involves two-step gaseous extraction of a sample in vessels of varying volume before and after the equilibrium phase is replaced with a pure gas (air or nitrogen). This method permits to analyse 5–50 ml water samples with benzene and toluene contents varying from the ppb to the ppm range within an error not exceeding 155. The analysis time is about 1.5 h. The presence of non-volatile organic or mineral substances does not influence the determination. This method is unsuitable to heterogeneous systems (aqueous oil emulsions): before carrying out the analysis for the hydrocarbon content these systems have to be homogenized first.
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  • 72
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Open tubular (capillary) columns ; Glass columns ; Fused-silica columns ; Column testing
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    Topics: Chemistry and Pharmacology
    Notes: Summary Column characteristics affecting the chromatographic behavior of glass and siliceous glass (“fused silica”) capillary columns include the dimensional uniformity of the column, the physical and chemical characteristics of the column wall and the characteristics of the liquid phase. In the case of the coated column the uniformity and thickness of the liquid phase film are the most important criteria affecting column reproducibility. The paper discusses these factors and their influence on column performance.
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  • 73
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    Chromatographia 14 (1981), S. 203-211 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Quantitative analysis ; Copper oxide converter ; Inorganic gas analysis ; Determination of fluorine and oxygen ; Hydrocarbon analysis ; Wine analysis
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    Topics: Chemistry and Pharmacology
    Notes: Summary A review of past activities concerning selected industrial analytical problems is given. This includes the following question: preparation of pure gas mixtures to be used for calibration, catalytic conversion of ester and pyridin samples to carbon dioxide and a one-point calibration method using peak heights, both for quantitative analysis, analysis of gas mixtures containing fluorine and inorganic fluorine compounds and the determination of the oxygen and fluorine content of the sample, separation and identification of hydrocarbons in shale oil and petroleum fraction samples, and analysis of wine.
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  • 74
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    Chromatographia 15 (1982), S. 704-706 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Isopropyliden-sorboses ; TMS-derivatives ; GC-MS combined technique ; Mass spectra
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    Topics: Chemistry and Pharmacology
    Notes: Summary A method has been developed using gas chromatography — electron impact mass spectrometry for the determination of the di-0-isopropylidene-sorbofuranose and mono-0-isopropylidene-sorbofuranose. The compounds are separated as their trimethylsilyl derivatives on a capillary column coated with the stationary phase SE-52. The mass spectra show that the silylation reaction is quantitiative and that the isopropylidene groups does not change.
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  • 75
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    Chromatographia 15 (1982), S. 183-185 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Analysis of ethylbenzene hydroperoxide ; Time normalization method
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    Topics: Chemistry and Pharmacology
    Notes: Summary A gas chromatographic method, based on the time normalization technique, is described for the analysis of ethylbenzene hydroperoxide in mixtures containing ethylbenzene, acetophenone, 1-phenylethanol, benzaldehyde and phenol. Different liquid phases were tested and the best results were obtained with tricresyl phosphate and neopentyl glycol sebacate. The influence of the support, the liquid loading and the gas velocity are discussed.
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  • 76
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    Chromatographia 15 (1982), S. 625-630 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Open-tubular (capillary) columns ; Comparison of liquid phases ; Influence of temperature ; Retention index data
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    Topics: Chemistry and Pharmacology
    Notes: Summary The influence of temperature and liquid phase film thickness of open-tubular (capillary) columns on the retention index values of hydrocarbons on methylsilicone liquid phases is discussed. Data obtained on methylsilicones and squalane are compared. Retention index values of 43 hydrocarbons between 40 and 70 °C on OV-101 liquid phase are listed.
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  • 77
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    Chromatographia 15 (1982), S. 351-354 
    ISSN: 1612-1112
    Keywords: Supported catalysts ; Reserved-flow GC ; Drying step ; Gas chromatography
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    Topics: Chemistry and Pharmacology
    Notes: Summary Application of reversed-flow gas chromatography to study the drying step in the preparation of supported catalysts is proposed. It is demonstrated that this technique can be applied to investigate the kinetic law followed, as well as to obtain kinetic parameters of drying (rate constants, activation energies and frequency factors). Amaterial illustrating this application is γ-Al2O3 impregnated with usual organic solvents (n-C5H12,n-C6H14,n-C7H16, CH3COCH3 and CH3CH2OH). It was found that in all cases above a simple first-order law based onone kind of active site is followed. Moreover, it was observed that the activation energyE a of the drying process increases almost linearly with the relative molecular mass of the solvent, whereas for the same solventE a increases with the amount used. The operation of a kinetic compensation effect suggests “similar” activated complexes of the various solvents used.
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  • 78
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Fused silica capillaries ; New polar phases: OV-1701 and RSL-310 ; Immobilization
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    Topics: Chemistry and Pharmacology
    Notes: Summary The possibilities of OV-1701 and RSL-310, two new stationary phases, have been evaluated for capillary gas chromatography in fused silica columns. OV-1701 is a cyanopropylphenyldimethyl polysiloxane of moderate polarity possessing excellent chromatographic characteristics. The phase exhibits high coating and chromatographic efficiencies, high temperature stability and is suitable for cross-linking. RSL-310 is a polar liquid stationary phase yet to be permanently bonded in a capillary column. The selectivity of both phases extends the applicability of fused silica columns.
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  • 79
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Aqueous samples ; Direct injection ; Traces of ketones and halogenated hydrocarbons ; Environmental analysis
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    Topics: Chemistry and Pharmacology
    Notes: Summary Procedures for the quantitative analysis of industrial effluents which involve concentration by solvent extraction or the purge-and-trap method are time-consuming, labor-intensive, and prone to error. Direct aqueous injection gas chromatography using an electron-capture detector for the analysis of volatile halocarbons at the ppb level is in routine use in many laboratories. We now discuss the development of a similar protocol for the analysis of volatile polar organics such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and tretrahydrofuran using a flame-ionization detector.
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  • 80
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Nitrogen-specific detector ; Flash methylation ; Barbital and pentobarbital ; Blood analysis
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    Topics: Chemistry and Pharmacology
    Notes: Summary A sensitive and simplified method is described for the determination of barbital (B) and pentobarbital (PB) in blood using gas chromatography with a nitrogen-specific flame ionization detector. After a simple one-step extraction, B and PB were reconstituted in trimethylanilinium hydroxide and introduced directly into the gas chromatograph. Lower limits of detection was 0.14 μg/ml for B and PB in either water or blood solutions. The recoveries for B from water and blood were 90 and 88%, respectively; for PB they were essentially complete. The average between-run and within-run coefficients of variation for B from water and blood were lower than 7.8%, whereas those of PB were lower than 3.0%. The scale and sensitivity of detection for B and PB were found to be suitable for use in pharmacokinetic studies in the rat.
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  • 81
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    Chromatographia 23 (1987), S. 423-426 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Complexation ; Mercaptosilane chemically bonded phase ; Transition metal complexes ; Olefinic π-complexes
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    Topics: Chemistry and Pharmacology
    Notes: Summary A column packing containing thiol groups chemically bonded to the silica surface was synthesized. The thiol functional groups were used as ligands capable of forming stable complexes with Cu(II). The prepared material was characterized by gas chromatography using unsaturated linear and branched hydrocarbons as well as cyclic and aromatic hydrocarbons. The occurrence of specific metal—olefin interactions resulting from the formation of π-complexes during the chromatographic process was observed.
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  • 82
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Backflushing, peak-cutting technique ; Trace analysis
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    Topics: Chemistry and Pharmacology
    Notes: Summary A backflusing, peak-cutting method was developed for the analysis of trace components present in the tail of a major component peak. Using a helium-ionization detector, the minimum detectable concentration (MDC) was: oxygen in hydrogen, 0.5ppm; nitrogen in oxygen or argon, 1ppm; and methane and carbon monoxide in nitrogen, 1ppm. The corresponding MDC values for the conventional single-column method were 7.2ppm, 8.3ppm, and 14 and 5ppm, respectively. Equations used to predict the retention time are given. The accuracy of the predicted retention time is about two percent compared to experimental results.
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  • 83
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Alkylthiazoles ; Energy contributions of the alkyl groups ; Retention indices
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    Topics: Chemistry and Pharmacology
    Notes: Summary Retention indices and their energy equivalents were determined for ten alkylthiazoles analysed on the stationary phases Apiezon L, Triton X-305 and Carbowax 1000. It was found that the energy contributions of identical alkyl groups to the partial molar free energy of sorption of a molecule are not equivalent. Smaller energy contribututions are due to the α-position of alkyl groups with respect to the heteroatoms in the thiazole ring (α-effect). This effect was most pronounced for 2-alkylthiazoles. Higher sorption energies were found for dimethylthiazoles with two methylgroups in a vicinal position. The retention indices were predicted for ten other di- and tri-substituted methyl, ethyl and propyl thiazoles on the basis of the so-called α- and ortho-effects. The predicted values are in good agreement with the experimentally determined values.
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  • 84
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Liquid crystal ; Capillary columns ; Retention data ; Stationary phase film thickness ; Column surface quality
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    Topics: Chemistry and Pharmacology
    Notes: Summary Glass capillary columns were prepared from non-deactivated and deactivated glass and coated with (2-methyl-4-[trans-4-n-propyl-cyclohexylcarbonyloxy]-benzoic acid-[4-n-heptyloxy-phenylester]) as the liqud phase, in different film thicknesses. The columns were tested using substances of different structures and polarities. It was verified that the capacity factors, retention indices and selectivity significantly depend on the thickness of the liquid crystalline stationary phase film and the quality of the tube, particularly in the case of columns with thin films. Trasition temperatures (melting and clearing point) of the liquid crystal are also dependent on these two factors.
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    Chromatographia 25 (1988), S. 21-24 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Sample concentration ; Chromatographic evaporation ; Solvent effect
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    Topics: Chemistry and Pharmacology
    Notes: Summary Several micro-techniques for the removal of solvent from dilute solutions of volatile compounds have been compared. Large solute losses were experienced when the conventional blow-down technique was applied. Better yields could be obtained with static evaporation procedures, as long as an effective reflux was maintained. However, careful optimization of the vessel design and operating conditions is necessary. The most efficient volume reduction technique was shown to be chromatographic evaporation. Quantitative recoveries were obtained for the compounds tested and the process was significantly faster than static concentration. Moreover, operating conditions (gas flow, temperature) are less critical. With modifications, the principle can be used for the concentration of large sample volumes down to a few microliters.
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  • 86
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Esterification in aqueous solution ; n-Butyl esters of amino acids
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    Topics: Chemistry and Pharmacology
    Notes: Summary Amino acids have been esterified with n-butanol and isobutanol in the presence of perchloric acid. It has been established that in the concentration range of [H2O]/[n-BuOH]=0.10–0.40 esterification can be utilized for the determination of alanine, glycine, valine, leucine, proline, methionine, aspartic acid, phenylalanine, tyrosine, glutamic acid, lysine, arginine, histidine and cystine. In the case of [H2O]/[i-BuOH] =0.05–0.20 the esterification yield decreases from 100% to 70%, in proportion to the water content.
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    Chromatographia 20 (1985), S. 681-682 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Geothermal gases ; Molecular sieves ; Low temperature separations
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    Topics: Chemistry and Pharmacology
    Notes: Summary The gases evolved from geothermal fields, after condensation of H2O, CO2, H2S and NH3 in caustic solution, contain He, H2, Ar, O2, N2, CH4 and higher hydrocarbons. The analysis for the major components in these residual gas mixtures can be achieved by use of two simple gas chromatographs in parallel, and using 5Å molecular sieve. The separation of He and H2 to baseline is achieved by using low temperatures (30°C) coupled with a relatively long column; and the difficult separation of Ar and O2 is achieved by use of a cryogenically cooled column. The use of switching valves to backflush and bypass columns ensures that a minimum time for analysis can be achieved whilst retaining baseline separations of the He/H2 and Ar/O2 pairs.
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    Chromatographia 20 (1985), S. 685-688 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Fuming sulphuric acid-ethanol esterification ; Ethyl and methyl esters of herbicides
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    Topics: Chemistry and Pharmacology
    Notes: Summary A fuming sulphuric acid-ethanol esterification method has been applied to chlorophenoxy acids and some other herbicides. This method is compared with esterification by iodoethane and diazomethane. The chlorophenoxy acids studied were: 2,4-D, dichlorprop, MCPA, MCPB, mecoprop and 2,4,5-T. Other herbicides studied were: benazolin, bentazone, bromophenoxime, bromoxynil, chlorthal, dicamba, 3,6-dichloropicolinic acid, dinoseb, ethephon, fluroxypyr, glyphosate, haloxyfop, ioxynil, picloram, 2,3,6-TBA and triclopyr. Fuming sulphuric acid-ethanol esterification can be successfully applied to chlorophenoxy acids, benazolin, 3,6-dichloropicolinic acid, dinoseb, fluroxypyr, haloxyfop, picloram and triclopyr. The reproductibility of the method is ±5%.
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  • 89
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Stationary phase polarity ; Polarity parameters ; Structure-retention relationships
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    Topics: Chemistry and Pharmacology
    Notes: Summary The new stationary phase polarity parameters BN and BS evaluated from the concept of the electric intermolecular interactions are used to describe the polarity of polyoxyethylene glycol dialkyl ethers and their sulphur analogs. Relations between the discussed parameters and accepted measures of surfactants' polarity are presented and discussed. The considered parameters are correlated with the compound structures. Structural increments for characteristic fragments of the molecule are calculated and use to predict BN and BS values.
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  • 90
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    Chromatographia 25 (1988), S. 134-138 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Sulfur ; n-Octane adsorption
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    Topics: Chemistry and Pharmacology
    Notes: Summary From the adsorption isotherms of n-octane on the surface of sulfur at 29.8°C and 40.6°C some thermodynamic functions were determined. On the basis of these data the structure of the adsorbed layer of n-octane is postulated. The molecular interactions and adsorption mechanism are also discussed. It is stated that both quasi-liquid and quasi-sold layers may be formed on the surface of sulfur depending on the surface coverage with n-octane.
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  • 91
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Step profile method ; Adsorption isotherm ; Water film pressure ; Surface free energy
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    Topics: Chemistry and Pharmacology
    Notes: Summary Investigation of water adsorption by the step profile method (Glueckauf method) was carried out with the help of a modified gas chromatography equipped with thermal-conductivity detector. On the basis of the adsorption isotherm obtained, the water film pressure and the polar component of the surface free energy of quartz were calculated. The calculated value of the polar component of the surface free energy of quartz agrees with analogous values obtained by other methods.
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    Chromatographia 25 (1988), S. 313-318 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Retention index ; Slope of log plot ; Homologous series ; Partition coefficient
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    Topics: Chemistry and Pharmacology
    Notes: Summary The slope of the n-alkane log plot dt′R/dnc (t′R=adjusted retention time; nc=carbon number) for a stationary phase can be used to obtain the retention index of an unidentified substance in a chromatogram containing only one peak with a known retention index, or to predict the retention time of a substance from that of a different homolog in the same series. It can also be used to translate retention indices into relative retention time, partition coefficient or specific retention volume. Published values of the slope are collected and critically evaluated. Equations are deduced that predict its approximate value at a specified temperature given the value at only one other temperature.
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  • 93
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    Chromatographia 25 (1988), S. 393-396 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Separation of optical isomers ; Chirasil-Val capillary columns ; Amino acid esters
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    Topics: Chemistry and Pharmacology
    Notes: Summary D,L-amino acids were derivatized with (+), (±)-2-butanol or N-trifluoroacetyl-L-prolyl chloride (L-TPC) and then chromatographed. Four optical isomers were separated on a Chirasil-Val capillary column. By this method, the concentration of optical impurities arising from the commercial optically active reagents can be determined. The observed abnormal elution orders of enantiomeric amino acid esters may be caused by a selective intermolecular force.
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  • 94
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Essential oils ; Evaporation rate ; Perfume composition
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    Topics: Chemistry and Pharmacology
    Notes: Summary A simple method was developed for the determination of the evaporation rate of essential oils and perfumery composition using gas chromatography with temperature programming. The volatility of 19 essential oils and 17 perfumery composition was evaluated. The method is useful for different comparative measurements.
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  • 95
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    Chromatographia 25 (1988), S. 598-602 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Capillary columns ; Steroid profiles
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    Topics: Chemistry and Pharmacology
    Notes: Summary Steroid conjugates are hydrolysed enzymatically using β-glucuronidase after extraction from urine using a solid phase extraction cartridge. After hydrolysis the free steroids are removed from the matrix, again utilising solid phase extraction. Derivatisation of the free hydroxyl groups using Hydrox-Sil AQ produces the respective TMS ethers which are extracted into hexane, in which solvent they are stable for many days. Capillary GC analysis with flame ionisation detection produces a profile of the steroids present in the sample. This technique is suitable for following changes in the urinary excretion profiles of patients undergoing investigation for a variety of steroid production-related diseases.
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  • 96
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    Chromatographia 25 (1988), S. 609-612 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gas chromatography ; Triglyceride composition of grapes ; Identification system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The triglyceride composition of the Tempranillo grape (Vitis vinifera) has been examined by a combination of HPLC and GLC. To identify the triglycerides, equations were applied relating log k′ with the molecular variables: equivalent carbon number, chain length and number of double bonds in each of the fatty acids in the glycerides. Ten triglycerides were found, the principal ones being trilinolein (35.75%), dilinoleyl-olein (21.03%) and dilinoleyl-palmitin (17.02%).
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    Chromatographia 25 (1988), S. 655-658 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Structure-retention relationships ; Connectivity indices, topological indices ; Alkenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Retention indices of different alkenes are correlated with connectivity and topological parameters. The appropriate statistically valid relations hips are derived and discussed.
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  • 98
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    Chromatographia 25 (1988), S. 735-736 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; α,ω-diiodoperfluoroalkanes ; Separation ; identification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of α,ω-diiodoperfluoralkanes on a glass capillary column coated with OV-101 methylsilicone was investigated. Retention indices were determined at three temperatures (140, 150 and 160°C). The correlation between the retention indices and the boiling points of the investigated compounds was studied.
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    Chromatographia 25 (1988), S. 731-734 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Retention Index (l) ; Temperature dependence of Retention Index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A linear dependence of (T−T1)/[1(T)−1(T1)] on temperature (considering the retention index 1(T1) at temperature T1 as a standard value) is derived. Both ther retention index at an assigned temperature and the temperature dependence of the retention index can be calculated from retention data measured at two temperature-programing rates.
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    Chromatographia 26 (1988), S. 171-177 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; GC/MS analysis ; Polycyclic aromatic hydrocarbons ; Bituminous coal ; Brown coal ; Plant waxes ; Thermodesorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Polycyclic aromatic hydrocarbons (PAH) today are ubiquitous detectable constituents of recent sediments. The compounds are adsorbed on particulate emissions and are thus transferred to the environment. To date the analysis of PAH in sediments, dust samples and plant material is based mainly on the application of solvent-extraction methods followed by liquid chromatography and/or gas chromatographic separation of the extracts. An alternative approach for the analysis of PAH in solid samples such as coal, sediments, dust samples and plant waxes is shown in this contribution. A commercially available device for the analysis of volatile compounds present in solid matter is connected on-line to a GC/MS system. The device enables the thermal desorption of hydrocarbons at a temperature of 320°C. Subsequently, the hydrocarbons trapped on the initial part of the capillary column are analyzed by GC/MS. The application of mass chromatography provides the possibility of detection and quantitation of PAH in complex mixtures even when they coelute with other compounds. The sample amount required varies between 1 and 10 mg depending on the hydrocarbon content.
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