Simultaneous determination of danshensu, rosmarinic acid, cryptotanshinone, tanshinone IIA, tanshinone I and dihydrotanshinone I by liquid chromatographic–mass spectrometry and the application to pharmacokinetics in rats

A sensitive and specific liquid chromatography–tandem mass spectrometry method (LC–MS) was developed and validated for the separation and simultaneous determination of danshensu, rosmarinic acid and tanshinone compounds including cryptotanshinone, tanshinone I, dihydrotanshinone I and tanshinone IIA in rat plasma. Chromatographic separation of the analytes was successfully achieved on a C18 column using a mobile phase composed of acetonitrile–water containing 0.5% glacial acetic acid. This method demonstrated good linearity and did not have endogenous material interfering with the active compounds and I.S. peaks. The limit of quantification of danshensu, rosmarinic acid, cryptotanshinone, dihydrotanshinone I, tanshinone I and tanshinone IIA were 5, 0.75, 0.1, 0.1, 1 and 0.5 ng/mL. The average extraction recoveries of these analytes from rat plasma were all over 60%. The precisions determined from five days were all within 10%. This method has been successfully applied in the simultaneous quantification and the pharmacokinetic studies of these six compounds in animals which were orally administered with danshen preparations.