Determination of the plumbagin content in the stems of Plumbago zeylanica during different months in Guilin

The plumbagin content in stems of Plumbago zeylanica was determined during different months in Guilin,China,using RP-HPLC,methanol and H 2 O(70:30) as mobile phase and UV detection at 254nm.Linear range over 0.00048-0.0240mg.mL-1 of plumbagin was obtained.Recovery rate was within 96.9%-100.0%.The content in stems of P.zeylanica was the highest in October when the plant was the most thriving and biggest in size.It was therefore considered that October was the best time for collecting stems.