Objective: To develop UPLC-MS/MS for determination of 8-O-acetyl shanzhiside methyl ester and shanzhiside methyl ester in rat plasma and their pharmacokinetics study. Method: Plasma was precipitated with acetonitrile

mobile phase was consisted of acetonitrile and 0.1% formic acid solution with gradient elution pumped at a flow rate of 0.4 mL·min-1.Analysis was detected with positive electrospray ionization in multiple reaction monitoring (MRM) mode and rutin was used as internal standard. Result: Excellent linear calibration curves of 8-O-acetyl shanzhiside methyl ester and shanzhiside methyl ester were obtained in the concentration range of 1-250 μg·L-1

their lower limits of quantification were 0.2 μg·L-1.Intra-day and inter-day relative standard deviations of low

medium and high quality control samples were all less than 8.8%;Average recovery of 8-O-acetyl shanzhiside methyl ester were (103.89±9.18)%

(99.34±6.63)% and (95.88±3.69)%

while average recovery of shanzhiside methyl ester were (105.33±8.64)%

(101.55±1.22)% and (96.89±5.42)%

respectively. Conclusion: This method is simple

rapid and sensitive

which is suitable for pharmacokinetics analysis of 8-O-acetyl shanzhiside methyl ester and shanzhiside methyl ester in rat plasma.