Simultaneous determination of seven flavonoids in Epimedium using pressurized liquid extraction and capillary electrochromatography

Herba Epimedii (known as Yinyonghuo in China) is one of the commonly used Chinese medicines. Flavonoids are considered as its active components. In this study, a CEC method was developed for the simultaneous determination of seven flavonoids, including hexandraside E, kaempferol-3-0-rhamnoside, hexandraside F, icariin, epimedin A, B, and C, in Epimedium using baicalein as internal standard (IS). The influence of relevant parmeters such as buffer concentration, pH, and proportion of ACN was investigated and optimized. Baseline separation was obtained using a Hypersil C, capillary (3 pm, 100 mu m/25 cm) with a mixture of 20 mM phosphate buffer (pH 4.0)/ACN (70:30 v/v) as mobile phase running at 30 kV and 25 degrees C in 20 min. All calibration curves showed good linearity (r(2) > 0.9992) within test ranges. The LOD and LOQ were lower than 8.6 and 42.8 mu g/ml,, respectively. The RSDs of intra- and interday for relative peak areas of seven analytes were less than 3.1 and 4.4%, and the recoveries were 95.2-103.3%. Samples of different Epimedium species were analyzed rising the validated method, which is useful for quality control of Epimedium and its medical preparations.