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  • 1
    Electronic Resource
    Electronic Resource
    A thermodynamic criterion for the identification of the functional group of aliphatic compounds by gas chromatography (1984)
    Springer
    Chromatographia 18 (1984), S. 449-455 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Thermodynamic relationships ; Retention index ; Peak identification
    Source: Springer Online Journal Archives 1860-2000
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262976
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  • 2
    Electronic Resource
    Electronic Resource
    Universal system for liquid stationary phase classification on the basis of thermodynamical data (1979)
    Springer
    Chromatographia 12 (1979), S. 533-538 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Sorbents: liquid phases, supports, adsorbents ; Thermodynamical classification ; Polarity and selectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Equations modifying Rohrschneider's relationship between ΔI and thermodynamical characteristics values are derived. Polarity in chromatography is discussed as a possibility of stationary phases or absorbents to enter into intermolecular interactions and is determined on the basis of the partial molar free energies of solution (ΔG) of six test substances. A simple method for the calculation of stationary phase polarity in terms of ΔG from retention indices and McReynolds constants is given. Equations are presented for the calculation of stationary phase selectivity utilizing ΔG data tabulated for selected test substances. The thermodynamical basis of selecting a reference phase for a unified system expressing the selectivity of stationary phases which can also be applied for adsorbents is suggested. The energy equivalent to an index unit, ΔGi.u., is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02265469
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  • 3
    Electronic Resource
    Electronic Resource
    Calculation of the thermondynamic values of alkylthiazoles from the Kovats retention indices on the basis of the non-linear additivity principle (1987)
    Springer
    Chromatographia 23 (1987), S. 595-598 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Alkylthiazoles ; Energy contributions of the alkyl groups ; Retention indices
    Source: Springer Online Journal Archives 1860-2000
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02324871
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  • 4
    Electronic Resource
    Electronic Resource
    The reason for non-linear variation of specific retention volumes and retention indices for members of homologous series of organic compounds (1983)
    Springer
    Chromatographia 17 (1983), S. 613-622 
    Details
    ISSN: 1612-1112
    Keywords: Gas Chromatography ; Retention index ; Thermodynamic relationships
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Universal equations have been obtained for aliphatic homologous series permitting the calcualtion of the specific retention volume, retention index, partial free energy of sorption and the change in the energy contribution of a methylene unit depending on the length of the carbon chain. Possible reasons for the violation of the linearity principle of additivity of energy contributions of the free energy of sorption are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02261945
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  • 5
    Electronic Resource
    Electronic Resource
    Thermodynamic evaluation of the intermolecular interactions of potassium fluoride crystal dihydrate in gas chromatography (1989)
    Springer
    Chromatographia 28 (1989), S. 179-182 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; KF·2H2O as stationary phase ; Alcohols ; Organic bases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Potassium fluoride crystal dihydrate is used as the stationary phase for the rapid analysis of polar compounds in aqueous solutions. KF·2H2O is compared with some conventional stationary phases, organic salts and molten crystal hydrates of inorganic salts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02319643
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  • 6
    Electronic Resource
    Electronic Resource
    A method of calculating the specific retention volumes of substances from their retention indices and specific retention volumes of n-alkanes (1983)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 6 (1983), S. 269-272 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Retention indices ; Specific retention volumes ; n-Alkanes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The choice of stationary phase for gas chromatography is dictated by the nature of the analytes. Polarity and selectivity are known to play an important role. This paper suggests equations for calculation of specific retention volumes of any compounds from their retention indices.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240060509
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  • 7
    Electronic Resource
    Electronic Resource
    Intra- and intermolecular interactions in the first members of homologous series of carbonyl containing compounds in gas chromatography (1990)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 13 (1990), S. 47-51 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary columns, glass ; Packed columns ; Free energy of sorption ; Intramolecular interactions ; Intermolecular interactions ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Variation of the values of free energy of sorption of the methylene unit has been studied in the homologous series of n-alkyl methyl ketones, n-alkyl butyl ketones, n-alkyl acetates, and methyl esters of carboxylic acids, depending on the homologue number and the temperature of analysis. The experiment was carried out on a capillary column with a thick film of immobilized Silicone SE-54 and on packed columns with OV-210 and Silar-10C. An intramolecular donor-acceptor interaction between neighboring CH3— and C=O groups is assumed to be the reason for anomalously high values of free energy of sorption of the first CH2 unit in the series: RmC(O)OCH3, RmC(O)CH3, and RmC(O)C4H9. The anomaly disappeared in stationary phases containing strongly electronegative —CF3 and —CN groups because of specific inter molecular interactions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240130110
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  • 8
    Electronic Resource
    Electronic Resource
    GC behaviour of symmetrical n-dialkyl sulphides under isothermal and temperature programming conditions (1981)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 4 (1981), S. 6-10 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Retention index calculation by correlation techniques ; Use of n-dialkyl sulphides as standards ; Use of selective detectors ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Retention indices were determined for a homologous series of n-dialkyl sulphides on three stationary phases (SE-30, OV-17 and XE-60) under isothermal and linear temperature programming conditions. Under these two different GC conditions, equations were derived for each of the three stationary phases which showed the dependence of retention index on the number of carbon atoms and the boiling points for a homologous series of n-dialkyl sulphides. The equation for the correlation isothermal retention index was shown to be applicable to the identification of n-dialkyl sulphides using linear temperature programming. It was found that the GC behaviour of n-dialkyl sulphides makes these compounds suitable for use as a standard series instead of n-alkanes for the calculation of retention indices in GC analysis in which detectors insensitive to n-alkanes are employed. The use of the homologous series of n-dialkyl sulphides for the calculation of sulphide retention indices can be great practical importance in the microanalysis of natural compounds. We have used this method successfully in the analysis of pesticides containing S-atoms.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240040103
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