Enantioseparation Of Amino Acids And Ofloxacin By Chiral Ligand Exchange Countercurrent Chromatography

Amino acids are important chemical raw materials and pharmaceutical intermediates.The research on chiral separation of amino acid enantiomers is of great significance.Chromatographic resolution is one of the most effective methods for chiral separation,and chiral ligand exchange chromatography is the most effective method for the resolution of underivatized amino acids in chromatography.Separation of amino acids by chiral ligand exchange countercurrent chromatography has potential application prospect.The paper concentrates mainly on the enantioseparation a series of racemic amino acids by chiral ligand exchange countercurrent chromatography,including 15 kinds of α-amino acids,β-phenylalanine,indoline-2-formic acid and ofloxacin.An equilibrium model for enantioseparation of phenylalanine was proposed.For the successful enantioseparation of racemic amino acids in high speed countercurrent chromatography,the enantioselective liquid-liquid extraction was performed to determine the distribution ratio of phenylalanine and to investigate the effects of influence factors,including separation temperature,aqueous pH,kinds of transitional metal ions,type and concentration of chiral ligand and metal ion on distribution ratio and enantioseparation factor,and the optimum conditions for the separation were obtained.Phenylalanine、leucine、norleucine、isoleucine、valine、indoline-2-formic acid were successfully baseline enantioseparated by analytical high speed countercurrent chromatography with an optimized solvent system.The two-phase solvent system was composed of n-hexane-n-butanol-water,to which N-n-dodecyl-L-proline,N-n-dodecyl-L-hydroxyproline or N,N-didodecyl-L-isoleucine was added in the organic phase as chiral ligand and cupric acetate was added in the aqueous phase as transitional metal ion.Based on partition equilibria of phenylalanine in biphasic solvent system,dissociation equilibria,ligand exchange equilibria and mass conservation principle,an equilibrium model was proposed in enantioseparation of phenylalanine by chiral ligand exchange high speed countercurrent chromatography,which could provide a theoretical basis for optimization in enantioseparation by chiral ligand exchange countercurrent chromatography.