Objective: To develop a rapid

reliable and sensitive method of UPLC-MS/MS with an atmospheric-pressure chemical ionization(APCI) source for determination of tanshinone ⅡA and salvianolic acid B in rat plasma after oral administration of Yindan Xinnaotong soft capsules. Method: UPLC-MS/MS was employed to measure plasma concentration at different time after ig administration of Yindan Xinnaotong soft capsules with 2.4 g·kg-1.Analysis was detected by APCI in multiple reaction monitoring (MRM) mode.Detection of tanshinone ⅡA and salvianolic acid B was using following transitions of m/z 295.0-249.0 for tanshinone ⅡA

m/z 717.1-519.0 for salvianolic acid B and m/z 271.1-122.8 for baicalein.DAS 2.1.1 software was used to calculate pharmacokinetic parameters. Result: Calibration curve ranges were 1-100 and 5-500 μg·L-1 for tanshinone ⅡA and salvianolic acid B

respectively.Mean recovery of them ranged from 72.43% to 93.92%

intra-day and inter-day precisions were in the range of 2.73%-9.87% and accuracies were between 92.65% to 106.26%.Cmax of tanshinone ⅡA and salvianolic acid B were (38.34±17.35)

(32.00±15.43) μg·L-1

Tmax of them were (0.25±0.23)

(0.75±0.18) h. Conclusion: This method developed in the present study using UPLC-MS/MS is highly sensitive

accurate

rapid and suitable for pharmacokinetic study of tanshinone ⅡA and salvianolic acid B from Yindan Xinnaotong soft capsules in rats.