Simultaneous Determination of Six Flavonoid Compounds in Lotus Leaves by High Performance Liquid Chromatography

To simultaneously determine the contents of six flavonoids (rutin, hyperoside, astragalin, quercetin, kaempferol and isorhamnetin) in lotus leaves and related tea products, eight lotus leaf samples from different companies were detected by HPLC. The prepared samples were separated by Agilent TC-C18(2) (150 mm × 4.6 mm, 5 μm) at 25℃ with a step linear gradient using 0.5% formic acid-water (A) and 0.1% formic acid-acetonitrile (B) at a flow rate of 1.0 mL/min. The detection wavelength was 360 nm. Results showed that the concentration ranges of rutin, hyperoside, astragalin, quercetin, kaempferide and isorhamnetin were 1.6-160, 1.8-180, 2.16-216, 1.4-140, 2.12-212 and 1.6-160 μg/mL, respectively. Between these ranges, the linearity of the six flavonoids were well-presented (R² > 0.9992) in a certain concentration range. The RSD values for the stability, repeatability, intra-day and inter-day precisions and recovery rates were all less than 2%. Eight lotus leaf samples from different companies were detected by the above method. The content of quercetin was the highest among the six flavonoids, and was highest in Batch No. 130802 from Company G. The method used in this study accurately detected the contents of six flavonoids in lotus leaves and tea products, and provided an effective way in which to determine the functional components and quality of lotus leaf products.