Simultaneous determination of phenolic acids by UPLC–MS/MS in rat plasma and its application in pharmacokinetic study after oral administration of Flos Lonicerae preparations

•Simultaneous analysis of phenolic acids as isomers in vivo was studied firstly.•The method was fully validated and applied to the pharmacokinetic study.•There were significant differences of isomers in the pharmacokinetic parameters.•Caffeoylquinic acids and dicaffeoylquinic acids as isomers needed to be separated. The current study aims to investigate the pharmacokinetic study of five phenolic acids (neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid, 3,5-dicaffeoylquinic acid and 3,4-dicaffeoylquinic acid) following oral administration of Flos Lonicerae preparations in rats. A rapid and sensitive ultra performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method was developed to simultaneously determine the five phenolic acids in rat plasma. After mixing with the internal standard (IS) tinidazole, plasma samples were pretreated by liquid–liquid extraction with ethyl acetate/n-hexane (9:1, v/v). The separation was performed on an Acquity UPLC BEH C18 column (100mm×2.1mm, 1.7μm) at a flow rate of 0.4mlmin−1, and acetonitrile/methanol (4:1, v/v)-0.4% formic acid was used as mobile phase. The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM) via electrospray ionization (ESI) source with positive ionization mode. All calibration curves had good linearity (r>0.991) over the concentration ranges of 0.74–378ngml−1 for neochlorogenic acid, 0.50–1030ngml−1 for chlorogenic acid, 1.9–250ngml−1 for cryptochlorogenic acid, 0.74–380ngml−1 for 3,5-dicaffeoylquinic acid, and 5.1–328ngml−1 for 3,4-dicaffeoylquinic acid. The intra-and inter-day precision were within 15% and the accuracy ranged from 86.2% to 114.1%.