SEPARATION OF OFLOXACIN ENANTIOMERS BY EXTRACTION WITH SOLVENT CONTAINING CHIRAL SELECTOR

AIMDistribution behavior of ofloxacin enantiomers was examined in the aqueous and organic solvent of a two-phase system containing a chiral selector, and the theory was provided for separation of racemic mixtures by solvent extraction. METHODSAlcohol containing 0.25 mol·L^-1 L-dibenzoyltartaric acid (L-DBTA), was used as organic phase, and Na₂HPO₄ buffer solution containing 0.14 g·L^-1 ofloxacin, was used as aqueous phase. The influence of pH on partition coefficient (K) and separation factor (α), was investigated in aqueous-organic phases. Significant enantioselectivity was observed with alcohols of different carbon number as solvents. Ofloxacin enantiomers were separated with hollow fiber membrane. RESULTSThe values of K for R and S enantiomers were all above 4.7, and α was up to 1.18, when racemic ofloxacins were extracted with L-DBTA in decanol at pH 6.86; the optical purity of the product in the outflow is above 90% through 11 hollow fiber membrane modules with 22 cm length. CONCLUSION L-DBTA in alcohol solvents is of strong enantioselectivity for racemic ofloxacins in Na₂HPO₄ buffer solution. pH and alcohol solvents are of big influence on K and α, and decanol and pH 6.86 are good for separation; a different degree of separation can be obtained by adjusting transfer unit numbers.