Preparation and application of a new ligand exchange chiral stationary phase for the liquid chromatographic resolution of α-amino acid enantiomers

A new liquid chromatographic ligand exchange CSP has been prepared by covalently bonding (S)-N,N-carboxymethyl undecyl leucinol monosodium salt onto silica gel and employed in resolving various α-amino acids. The new CSP was quite good in resolving various α-amino acids and the resolution results were dependent on the type and content of organic modifier in the mobile phase. From these results, a chiral recognition model using a lipophilic interaction between the tethering alkyl group of the CSP and the substituent at the chiral center of α-amino acids was proposed. The liquid chromatographic resolution of α-amino acids on the new CSP was also found to be dependent on the Cu(II) concentration in the mobile phase and the column temperature.