OPTICAL RESOLUTION OF RACEMIC ALPHA-AMINO-ACIDS ON A DYNAMIC CHIRAL STATIONARY-PHASE DERIVED FROM (S)-LEUCINOL BY LIGAND-EXCHANGE CHROMATOGRAPHY

A dynamic chiral stationary phase (CSP 7) for resolving racemic alpha- amino acids have been prepared by hydrophobically loading (S)-N,N-carb oxymethyl dodecyl leucinol monosodium salt onto a commercial reverse p hase octadecyl silica gel column. CSP 7 was successfully employed in r esolving various racemic alpha-amino acids. The chromatographic result s for resolving various racemic alpha-amino acids on CSP 7 have been f ound to be generally better as expected from the chiral recognition mo del proposed than those on the previously reported dynamic CSP (2), (R )-N,N-carboxymethyl dodecyl alaninol monosodium salt which is hydropho bically bound onto a commercial reverse phase octadecyl silica gel col umn. Especially, CSP 7 seems to be more attractive than CSP 2 in that CSP 7 shows reasonably good resolving ability for the broad range of r acemic alpha-amino acids at the high content of organic modifier (20 % CH3CN) in the aqueous mobile phase while CSP 2 shows very poor resolv ing ability.