Simultaneous quantification of eight major constituents in Herba Siegesbeckiae by liquid chromatography coupled with electrospray ionization time-of-flight tandem mass spectrometry.

A simple and reliable high-performance liquid chromatography coupled with electrospray ionization time-of-flight tandem mass spectrometry method was developed and validated for the determination of the major diterpenoids and flavonoids in the aerial parts of Herba Siegesbeckiae, including Kirenol, hythiemoside B, ent-16β,17,18-trihydroxy-kauran-19-oic acid, ent-17,18-dihydroxy-kauran-19-oic acid, ent-16β,17-dihydroxy-kauran-19-oic acid, 16α-hydro-ent-kauran-17,19-dioic acid, Rhamnetin, 3',4'-dimethoxy quercetin. The separation of eight compounds was performed on a Waters Symmetry Shield TM RP18 column (250mm×4.6mm i.d., 5μm) with gradient elution using a mobile phase consisting of 0.1% aqueous formic acid and acetonitrile containing 0.1% formic acid in selected ion monitoring mode. All calibration curves showed good linearity (r>0.999) within the test ranges. The precision was evaluated by intra- and inter-day tests, which revealed relative standard deviation (RSD) values less than 3.7%. The recoveries for the quantified compounds were between 97.4 and 101.2% with RSD values below 2.4%. According to the literatures, this study represents the first investigation of the simultaneous analysis of multiple components and the method can be applied to determine the amounts of the major compounds in Herba Siegesbeckiae.