A reversed-phase high-performance liquid chromatographic method was developed for the first time to simultaneously determine six major sesquiterpene lactones in Inula britannica L, that is, britannilactone, 1-O-acetylbritannilactone, hydroxylantolactone, 8-epi-ivangustin, 6-isobutylbritannilactone and 1,6-O,O-diacetylbritannilactone. The chromatographic separation was achieved with a linear gradient of acetonitrile in water with a flow rate at 1.0 mL min−1 using an Inertsil ODS-3 column (250 × 4.6 mm, 5.0 μm). Detection was carried out using a photodiode array detector at 210 nm. The calibration curves for the determination of all analytes showed good linearity over the investigated ranges (R2 > 0.999). Repeatability was evaluated by intra-day and inter-day assays and RSD values were less than 3.0%. The recoveries were between 93.9 and 104.6%. This developed method can be used for quality control purposes and allows for the differentiation between Inula britannica L., Inula hupehensis Ling., and Inula japonica Thunb.
