Determination of quinolizidine alkaloids in traditional Chinese herbal drugs by nonaqueous capillary electrophoresis

A rapid method for the determination of quinolizidine alkaloids by nonaqueo us capillary electrophoresis was developed. A total of 10 alkaloids (matrin e, sophocarpine, oxymatrine, oxysophocarpine, sophoridine, cytisine, sophor amine, aloperine, lehmannine and dauricine) could be easily separated withi n 18 min. A running buffer composed of 50 mM ammonium acetate, 10% tetrahyd rofuran and 0.5% acetic acid in methanol was found to be the most suitable for this separation. Five of these alkaloids were selected for further stud ies. The linear calibration ranges were 2.51-50.1 mu g/ml for sophoridine a nd sophocarpine, 2.71-54.2 mu g/ml for matrine, 3.30-65.9 mu g/ml for oxyma trine, and 3.10-62.0 mu g/ml for oxysophocarpine. The recovery of the five alkaloids was 98.0-101.3% with relative standard deviations from 1.03 to 2. 68% (n=5). The limits of detection for all 10 alkaloids were over the range 0.93-2.31 mu g/ml. The method was successfully applied to the phytochemica l analysis of alkaloid extracts from three commonly used traditional Chines e herbal drugs: Sophora flavescens Ait. (Kushen), S. alopecuroides L. (Kudo uzi or Kugancao) and S. tonkinensis Gapnep (Shandougen). (C) 1999 Elsevier Science B.V. All rights reserved.