Abstract: The purposes of this study were to establish an enantiomeric separation method for aleuritic acid by high performance liquid chromatography with evaporative light-scattering detection (HPLC-ELSD) and to explore the thermodynamic pattern of the chiral resolution process. The optimum chromatographic conditions were determined by investigated the effect of mobile phase composition and column temperature. The best separation was achieved on a DAICEL CHIRAL PAK IF column (25 cm × 0.46 cm i.d., 5 μm) held at 30 ℃ using a mobile phase composed of a mixture of 0.1% formic acid solution and acetonitrile (40:60, V/V) at a flow rate of 0.5 mL/min. The optimum parameters of ELSD were determined as 70 ℃, 60 ℃ and 1.6 L/min for evaporator temperature, drift tube temperature and carrier gas (high purity nitrogen) flow rate, respectively. The results showed that aleuritic acid obtained by strong alkali saponification was a mixture of two threo-enantiomers (65.5:34.5) with an enantiomeric excess (ee) value of 31%. Thermodynamic analysis indicated that there was a good linear relationship between lnα, lnk1 and lnk2 and 1/T with correlation coefficients (R2) of 0.997 2, 0.995 1 and 0.998 0, respectively. The difference of enthalpy change (ΔΔH) between two enantiomers was ?3 453.0 J/mol and the difference of entropy change (ΔΔS) was ?7.677 6 J/mol, suggesting that the resolution process was controlled by entropy change.

Key words: aleuritic acid, enantiomer, HPLC-ELSD, enantiomeric separation, thermodynamics