UPLC-MS/MS determination of paeoniflorin, naringin, naringenin and glycyrrhetinic acid in rat plasma and its application to a pharmacokinetic study after oral administration of Si-Ni-San decoction.

A UPLC-MS/MS method was developed for the simultaneous determination of paeoniflorin, naringin, naringenin and glycyrrhetinic acid in rat plasma. A Waters BEH C(18) column was used with a gradient mobile phase system of methanol-water containing 2 mM ammonium acetate. The analysis was performed on a positive ionization electrospray mass spectrometer via multiple reaction monitoring (MRM). One-step protein precipitation with acetonitrile was used to extract the analytes from plasma. The limits of quantification were 9.800 ng/ml for paeoniflorin, 5.100 ng/ml for naringin, 5.200 ng/ml for naringenin and 10.60 ng/ml for glycyrrhetinic acid, respectively. The intra- and inter-day precision (relative standard deviation, RSD) ranged 4.9-12% and 2.8-13%, respectively. The accuracy (relative error, RE) was from -7.3% to 7.5% at all quality control (QC) levels. The validated method was applied to a pharmacokinetic study in rats after oral administration of Si-Ni-San decoction. Crown