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  • Gas chromatography  (172)
  • Springer  (172)
  • American Geophysical Union
  • Copernicus
  • 1985-1989  (172)
  • 1960-1964
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Year
  • 1
    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.
    Type of Medium: Electronic Resource
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  • 2
    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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  • 3
    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.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    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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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    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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  • 6
    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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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    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.
    Type of Medium: Electronic Resource
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  • 8
    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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  • 9
    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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  • 10
    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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