Quantification of liensinine in rat plasma using ultra-performance liquid chromatography tandem mass spectrometry and its application to a pharmacokinetic study.

An ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed to determine liensinine in rat plasma using carbamazepine as the internal standard (IS). Sample preparation was accomplished through a protein precipitation procedure with acetonitrile to 0.1ml plasma sample. The analyte and IS were separated on an Acquity UPLC BEH C18 column (2.1mm×50mm, 1.7μm) with the mobile phase of acetonitrile and 0.1% formic acid in water with gradient elution at a flow rate of 0.40ml/min. The injection volume was 6μl. The detection was performed on a triple quadrupole tandem mass spectrometer equipped with electrospray ionization (ESI) by multiple reactions monitoring (MRM) of the transitions at m/z 611.6→206.2 for liensinine and m/z 237.1→194.2 for IS. The linearity of this method was found to be within the concentration range of 10-1000ng/ml with a lower limit of quantification of 10ng/ml. Only 3.0min was needed for an analytical run. The matrix effect was 93.8-107.4% for liensinine. The intra- and inter-day precision (RSD %) were less than 9.9% and accuracy (RE %) was within ±10.5%. The recovery ranged from 76.2 to 86.8%. Liensinine was sufficiently stable under all relevant analytical conditions. The method was also successfully applied to the pharmacokinetic study of liensinine in rats. The pharmacokinetic parameters were demonstrated as followed: t1/2 was 8.2±3.3h, Cmax was 668.4±156.9ng/ml, and AUC0→∞ was 1802.9±466.4ng/mlh.