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On the statistical independence of various column contributions to band broadening. Part 1: Second moment contributions from statistically independent, longitudinal diffusion in both phases

✍ Scribed by Nilsson, Olle

Publisher: John Wiley and Sons
Year: 1982
Tongue: English
Weight: 615 KB
Volume: 5
Category: Article
ISSN: 0935-6304
DOI: 10.1002/jhrc.1240050107

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✦ Synopsis

The total length-based second moment contribution from longitudinal sample diffusion in both phases on a column, o$,, is derived by adding individual partial differential contributions to a partial differential equation accounting for the longitudinal diffusion processes only. Although each diffusion-dispersed sample part is equilibrated between two phases, the resulting o&, (= 2k,f, + 2Rf,) can be interpreted as the sum of two independent contributions in accordance with the variance addition rule. (6, and 6, are the mean diffusion coefficients and f,and f, the mean residence times of the sample in the mobile and stationary phases, respectively.) The same expression is derived from the random walk model of Giddings by treating the diffusional process in each phase as statistically independent of the other processes. Under these conditions the broadening contribution from longitudinal diffusion in themobile phase is shown to be independent of the velocity profile.

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