Analysis of selected stilbenes in Polygonum cuspidatum by HPLC coupled with CoulArray detection.

The roots of three varieties of Polygonum cuspidatum were analyzed for resveratrol and its analogs. The powder of the dried roots was extracted with aqueous ethanol (60% v/v) and the extracts obtained were analyzed using RP HPLC with coulometric detection. A simple HPLC method with a multichannel CoulArray detector was developed for the determination of four stilbenes: resveratrol, its glucoside piceid, piceatannol, and its glucoside astringin. Analyses were carried out on a LiChrospher C18 (125 x 4.6 mm id, particle size 5 microm) column with a mobile phase of ammonium acetate (pH 3) and ACN in gradient mode. Four compounds were monitored by a CoulArray electrochemical detector. Potentials of eight electrochemical cells in series were set in the range of 200-900 mV. Optimization of the mobile phase pH was performed. Calibration curves showed good linearity with correlation coefficients (r(2))--more than 0.9975.