Enantioseparation of phenylsuccinic acid by high speed counter-current chromatography using hydroxypropyl-β-cyclodextrin as chiral selector.

High speed counter-current chromatography (HSCCC) was successfully applied to resolution of phenylsuccinic acid (PSA) with hydroxypropyl-β-cyclodextrin (HP-β-CD) as chiral selector (CS). The two-phase solvent system composed of n-hexane-methyl tert-butyl ether-0.1 mol L⁻¹ phosphate buffer solution with pH=2.51 (0.5:1.5:2, v/v/v) was selected. Influence factors involved in the chiral separation were investigated, including the concentration of chiral selector, pH value of the aqueous phase, the separation temperature, and the thermodynamic parameters of inclusion complex were calculated. The complex formation constants were determined using analytical instrument. Two HSCCC elution modes were studied and peak resolution equation was discussed. Under optimum separation conditions, 712 mg of PSA racemate was separated using preparative apparatus. The purities of both of the fractions including (+)-PSA and (-)-PSA from the preparative CCC separation were over 98.5% determined by HPLC and enantiomeric excess of (+)-PSA and (-)-PSA reached 97.6% and 98.6%, respectively. Recovery for the target compounds from the CCC fractions reached 80-82% yielding 285 mg of (+)-PSA and 292 mg of (-)-PSA.