Simultaneous HPLC Determination of Five Flavonoids in Flos Inulae

A simple and accurate reversed-phase high-performance liquid chromatographic (RP-HPLC) method has been developed for simultaneous determination of five flavonoids, spinacetin, quercetin, luteolin, 6-methoxyluteolin, and isorhamnetin, in an extract of the flowers of Inula britannica L., an important Traditional Chinese Medicine (TCM). Samples were extracted with 80% ethanol. Optimum separation and detection were achieved on an ODS-3 column with a methanol–acetonitrile gradient containing 0.49% (v/v) citric acid as mobile phase. The flow rate was 1.0 mL min⁻¹ and detection was at 360 nm. All calibration plots revealed linearity was good (r ² = 0.999) within the concentration ranges tested. Repeatability was evaluated by performing intra-day and inter-day assays; relative standards deviations (RSD) were less than 2.8%. Recovery of the five flavonoids was between 91.5 and 103.6%, with RSD less than 6.5%. The method was successfully used for analysis of seven samples of Flos Inulae from different parts of China and was found to be simple and efficient.