OBJECTIVE: Develop a chiral mobile phase additive HPLC method to separate and determine drug enantiomers in biological sample. METHODS: p - HPPH, Mephenytoin, Terbutaline, Chlorthalidone and Ofloxacin in biological sample were separated and determined using β - CD and chiral ligand exchange reagent as chiral mobile phase additive(CMPA). RESULTS: The R is 1. 10 ~ 1. 86 and n is 1642 ~ 2022 for four drug enantiomers using β - CD as CMPA. The R is 2.10 and n is 2560 ~ 2600 for oflxacin enantiomers using chiral...