ISSN:
1612-1112
Keywords:
Gas chromatography
;
Chemical potential of solutes
;
Ideal dilute solutions
;
Effect of size of solvent molecule
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Summary Gas-liquid chromatography allows the rapid experimental determination of the Henry coefficient of molecular probes if a number of precautions are taken. From a knowledge of the temperature dependence of the related standard chemical potential, the standard partial molar enthalpy, entropy and the mean heat capacity difference can be calculated. These functions determine the retention behaviour of the probe over a temperature range of more than 100 K with a precision better than 1%. They also give the necessary information to verify and to develop models for ideal dilute solutions and for the calculation of interaction forces. The choice of specific solvents is examined and justified and the experimental determination of retention data is discussed especially with reference to the precautions to observe in order to measure retention governed by gas-liquid partition only. Calculation of the standard chemical potential related to the molal Henry coefficient is advocated and the dependence of the standard chemical potential on size and shape of the solvent molecule based on data collected on paraffinic stationary phases is examined. This latter function is shown to depend linearly on the inverse of the molar mass of the solvent. Comparison with literature data demonstrates the general validity of this finding and that the shape of the solvent molecule is of less importance.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02269794
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