Optimization of Determination of Betulin in Betula platyphylla Bark by HPLC

[Objective] The determination of betulin in Betula platyphylla bark by HPLC was optimized. [Method] Using uniform design,betulin content in Betula platyphylla bark at different height above ground was determined. [Result]The result showed that the betulin content was the highest of 17. 56% at the height of 1. 5 m,and the lowest was 14. 51% at the height of 4. 0 m within the range of 0. 5-4. 0 m above ground,but there was no significant difference among different positions. [Conclusion] The optimal conditions for betulin extraction were explored to be ultrasonically extracted by absolute alcohol at 70 ℃(40 Hz,150 W) for 60 min.