Simultaneous separation and determination of four uncaria alkaloids by capillary electrophoresis using dual cyclodextrin system

The purpose of this study was to develop a simple, quick and precise capillary zone electrophoresis method (CZE) for the separation and determination of uncaria alkaloids using dual cyclodextrins as additives for the separation. The four analytes were baseline separated within 15 min at the applied voltage of 15 kV with a running buffer (pH 5.7) consisting of 40.0 mM phosphate buffer, 161.7 mM 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) and 2.21 mM mono-(6-ethylenediamine-6-deoxy)-β-cyclodextrin (ED-β-CD). Under the optimum conditions, a good linearity was achieved with correlation coefficients from 0.9989 to 0.9992. The detection limits and the quantitation limits ranged from 0.63 to 0.98 μg/mL and from 2.08 to 3.28 μg/mL, respectively. Excellent accuracy and precision were obtained. Recoveries of the analytes varied from 97.1 to 103.2%. This method was suitable for the quantitative determination of these alkaloids in the stem with hook of Uncaria rhynchophylla and the formulations of Uncaria rhynchophylla.