Determination of quinolizidine alkaloids in Sophora medicinal plants by capillary electrophoresis

A new capillary electrophoresis (CE) method for the determination of quinolizidine alkaloids in Sophora medicinal plants was developed. A total of seven alkaloid components (cytisine, sophocarpine, matrine, lehmannine, sophoranol, oxymatrine and oxysophocarpine) were separated within 15 min. The running buffer was a 50 mM phosphate buffer containing 1%HP-(beta)-CD and 3.3% isopropanol. The linear calibration ranges were 5.50–88.0 (mu)g ml^-1 for cytisine and lehmannine, 5.00–88.0 (mu)g ml^-1 for sophocarpine and sophoranol, 5.60–89.6 (mu)g ml^-1 for matrine and oxysophocarpine, and 24.0–384 (mu)g ml^-1 for oxymatrine. The recoveries of the seven alkaloids were 96.0–102.9% with relative standard deviations from 1.50 to 3.00% (n = 5). The method was successfully applied to different Sophora medicinal plants including Sophora flavescens, Sophora tonkinensis and Sophora alopecuroides.