Enantioseparation of the prodrug of chloramphenicol by capillary zone electrophoresis with electrochemical detection

Chiral separation of the enantiomers of threo-2-amino-1-(4-nitrophenyl)-1,3-propanediol, namely the prodrug of chloramphenicol (PCP), was carried out by capillary zone electrophoresis with electrochemical detection employing beta-cyclodextrin (beta-CD) as a chiral additive in strong alkaline solutions. The analytes were detected by electrochemistry using a copper disk electrode at +675 mV versus Ag/AgCl reference electrode. Both the free enantiomers and the enantiomer-cyclodextrin inclusion complexes could be detected using this approach, although the complexed forms gave lower oxidation currents than the uncomplexed ones. Factors affecting the chiral CE separation of the analytes, such as concentration of running buffer and beta-CD, applied voltage, were extensively investigated. Under the optimum conditions, baseline separation of the enantiomers could be accomplished in less than 18 min. In addition, an attempt was made to elucidate the plausible mechanism of the chiral recognition.