A liquid chromatography-mass spectrometry method was developed for the simultaneous quantitation of (2R,3R)-Dihydromyricetin and Myricetin in rat plasma samples to facilitate analysis of samples collected after administration of SenDeng-4 medicine. The plasma was subjected to protein precipitation with HCl (containing 10% ascorbic acid) and analyzed using electrospray ionization mass spectrometry in selected ion monitoring mode with Paeoniflorin as an internal standard. Good linearity for the two compounds was observed. The intra- and inter-day precision of analysis was, Author(s): Pu Bai [sup.1] [sup.2] [sup.3], Xin Jia [sup.1] [sup.2] [sup.4], Yu Dong [sup.1] [sup.2], Chula Sa [sup.1], Guoyuan Sun [sup.2] [sup.5], Xiaoling Zhu [sup.2] [sup.5] Author Affiliations: (1) grid.410612.0, [...]