8,2＇-Diprenylquercetin 3-methyl ether with significant anti-breast cancer activity is the main constituent of Tibetan medicine Sinopodophylli Fructus. In the present study, we developed and validated a rapid and sensitive ultra performance liquid chromatography-tandem mass spectrometry （UPLC-MS/MS） method for the determination of 8,2＇-diprenylquercetin 3-methyl ether in rat plasma. 8-Prenylkaempferol was used as the internal standard. The separation was carried out using Waters ACQUITY UPLC BEH C18 column （2.1 mm×100 ram, 1.7 μm） with a mobile phase consisting of acetonitrile and 0.1% formic acid in water on a gradient program at a flow rate of 0.4 mL＇min-1 and temperature of 30 ℃. Triple quadrupole mass spectrometric detection in negative ion mode was used for multiple-reaction monitoring of the transitions at m/z 451.30→177.25 and m/z 353.25→298.15 for 8,2＇-diprenylquercetin 3-methyl ether and 8-prenylkaempferol, respectively. The calibration curves were linear within the concentration range 0.1-2000 ng/mL （r = 0.9954）. The recoveries were 103%-115%, and the results were consistent across low, middle and high concentration levels. The intra- and inter-day precisions were within 15%, and the bias was between --6%-15%. This method was simple, rapid and sensitive, which could be applied to the determination of 8,2＇-diprenylquercetin 3-methyl ether in plasma and pharmacokinetic study in rats. Pharmacokinetic test indicated that the peak plasma concentration occurred in 2 h after the female rats were intragastrically administered with 8,2＇-diprenylquercetin 3-methyl ether at the dose of 100 mg/kg, and the biological half-life was 6.79 h. The blood drug concentration maintained equal amount for 20 h, which was conducive to the in vivo effects of drugs.
