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  • Biochemistry and Biotechnology
  • Gas chromatography
  • Life and Medical Sciences
  • Physical Chemistry
  • Wiley-Blackwell  (2)
  • 2000-2004  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 119-126 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; retention volume ; real gas carrier ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The problem of the calculation and interpretation of the net retention volume with a real gas as carrier is revisited. The properties of the carrier are described by a first order virial equation of state. The net retention volume of a solute is related to the mean flow rate of the carrier, therefore determination of the mean flow rate of a real gas carrier is reviewed. It is shown that the mean flow rate cannot be calculated from the mean column pressure. With a real gas carrier the local capacity factor depends on the local pressure of the real gas. The basic relationship between the net retention volume and the function describing this pressure dependence is also reviewed. Precise formulae as well as practical approximations are presented for the calculation of the mean flow rate, of the mean column pressure, and of a representative pressure related to the mean capacity factor.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-193X
    Keywords: Combinatorial chemistry ; Amides ; Gas chromatography ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A symmetric diketopiperazine scaffold 2 has been prepared in a very simple two-step procedure from L-aspartic acid dimethyl ester. This product (a tetracarboxylic acid equally protected at the two symmetric positions) has been employed as a template for the synthesis of mixed amide libraries in the solution phase using the SPSAF (simultaneous addition of functionalities) strategy. By judicious choice of the amines employed, it is possible to prepare parallel libraries containing hundreds of products using just a small number of different amines. We have also developed a simple method for monitoring the required conversion of the acid into amides based on an assay of the amount of iBuOH (determined by GC) formed during the coupling mediated by isobutyl chloroformate. We have observed that a conversion higher than 90% (iBuOH by GC) guarantees correct formation of the desired amides. This indirect method for assessing the conversion in a combinatorial reaction employing mixed reactants (SPSAF) can conveniently be used for the routine determination of libraries prepared in the solution phase. In a broader perspective, the present results contribute as a further step in the development of new and simple systems for monitoring the progress and evolution of combinatorial reactions
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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