NEW LOOK AT SOLVENT STRENGTH, SELECTIVITY, AND CONTINUOUS DEVELOPMENT

Extensive studies of adsorption models show that with the usual solute-solvent-adsorbent system, ln [(1 - RF)/RF] varies linearly with solvent strength. The ln [(1 - RF)/RF] versus solvent strength plots of most such systems also diverge mutually with decreasing solvent strength. For the usual systems, then, it can be easily established that selectivity (the center-to-center separation ability of a system) increases exponentially with decrease in solvent strength. The increase can be described simply and quantitatively in terms of RF. At the high selectivities that become available with decreased solvent strengths, the number of theoretical plates required for resolution usually becomes negligible. Spots are then resolved after only very short migrations. Spots so resolved remain essentially as detectable as they were at the origin. Such spots are conveniently developed by continuous development across relatively short beds of the adsorbent. The durations of such developments compare favorably with conventional developments. © 1979.