TARTARIC ACID-DERIVATIVES AS CHIRAL SELECTORS IN LIQUID-CHROMATOGRAPHY

Direct separation of enantiomeric amino-alcohols using tartaric acid derivatives as chiral complexing agents in organic stationary or mobile phases is described. Among the tartaric acid derivatives studied, only tartrates having hydroxyl groups attached to the asymmetric carbon atoms (C2) and (C3) free, gave enantioselective retention for ephedrine stereoisomers. (2R,3R)-di-n-butyl tartrate (DBT) dissolved in n-hexane as stationary liquid phase gave higher stereoselectivity than DBT in dichloromethane. Both hydrophilic (Nucleosil CN) and hydrophobic (porous graphitic carbon) solid supports were found to affect the retention and enantioselectivity when using a chiral liquid stationary phase. A retention model is presented and used qualitatively in the study of the effect of DBT concentration, organic solvent, addition of a competing amine and packing material on retention and stereoselectivity.