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Some problems concerning the efficiency of temperature gradient chromatography as compared to that of isothermal chromatography have been investigated. The following expression has been derived for temperature-gradient chromatography: where beta is the separation coefficient, alpha(1) and alpha(2), are the partition coefficients of two substances to be separated, R(f)(1) is the retardation factor for the substance with alpha(1)v is the volume of the eluent in the column, Deltav is the Supplementary volume of the eluent passing through the column owing to evaporation caused by the temperature-gradient, A(M). is the cross-sectional area of the mobile phase and d is the distance between the mid-points of the spots on the chromatogram. It has been shown that under the influence of the temperature gradient Deltav can be large enough for separation of two substances with an alpha(1)/alpha(2), ratio very close to 1. For this reason temperature-gradient chromatography with an open column is the most efficient means of separation so far known.
Liteanu
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Chaire de Chimie analytique, Université de Cluj, Cluj, RoumanieFrance.
Gocan
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