Enantiomeric enrichments adsorption

Using labeled Z)Z-Ala HCl these results were confirmed by obtaining a differential adsorption of 12-20% (percent adsorption on chloroform solution was studied using ( LC In this case t/-quartz preferentially adsorbed the i-Ala ester and /-quartz the D-Ala ester with enantiomeric enrichments of up to 1.5-12.4%. Such large differential enrichments are very doubtful and can indicate possible artifacts, although these data were eonfirmed later by Furoyama and coworkers by stereoselective adsorption on quartz According to Furoyama and... 

Discrimination between the enantiomers of a racemic mixture is a complex task in analytical sciences. Because enantiomers differ only in their structural orientation, and not in their physico-chemical properties, separation can only be achieved within an environment which is unichiral. Unichiral means that a counterpart of the race-mate to be separated consists of a pure enantiomeric form, or shows at least enrichment in one isomeric form. Discrimination or separation can be performed by a wide variety of adsorption techniques, e.g. chromatography in different modes and electrophoresis. As explained above, the enantioseparation of a racemate requires a non-racemic counterpart, and this can be presented in three different ways ... 

Enrichment of the optical activity of enantiomeric mixtures containing one antipode in excess - without resorting to an external chiral reagent - is well known to be feasible by crystallization, but not in that of adsorption". ... 

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