Objective:To develop an isocratic HPLC for the simultaneous
determination of all- trans -and 13- cis -retinoic acid(ATRA,13-cRA)in
human serum.Methods:The serum sample(1 mL)was extracted with 5 mL of ether for twice.The extract was analyzed on an μBondapak C 18 (3 9 mm×300 mm)column with a mobile phase consisting of 85 Vols of methanol and 15 Vols of NH 4Ac buffer(pH 6 0)at 22 ℃.The flow rate was 0 8 mL·min -1 .The retinoids were detected at 340 nm and quantitated by
internal standard method,DMAB was used as an internal standard.Results:The linearity of method was in the range of 0 8 to 1 120 μg·L -1 for ATRA and 0 82 to 1 312 μg·L -1 for 13-cRA.The limit of
determination was 0 6 μg·L -1 in serum for both ATRA and 13-cRA.Average recoveries were 98 86%～105 2% for ATRA ,101 6%～101 8% for 13-cRA.Within-day and between-day percision of determination were 0 84%～5 5% for ATRA and 1 4%～5 7% for 13-cRA.Conclusion:This method is sensitive,accurate and good enough to be utilized for the investigation of the clinical pharmacokinetics of ATRA.