Analysis of isoquinoline alkaloids in medicinal plants by capillary electrophoresis mass spectrometry

The technique of capillary electrophoresis - mass spectrometry (CE-MS) was applied for determination of isoquinoline alkaloids in crude methanolic ext racts of medicinal plants. For the CE separations ammonium formate buffer s olutions (70 or 100 nM, pH 3.0 or 4.0) containing 10% methanol or 20-60% ac etonitrile as additives were used. The applied voltage was 25 kV, the therm ostating temperature was kept constant at 25 degrees C. Coupling with the m ass spectrometer was performed via an atmospherical pressure ionization (AP I) interface and the electrospray ionization technique (ESI). As sheath Liq uid 5 mM formic acid in acetonitrile at a flow rate of 3 mu L/min was used. The spray voltage was 4.5 kV and the temperature of the heated capillary w as chosen to be 200 degrees C. Detection in the positive ionization mode re sulted in mass spectra showing either the molecular ions [M](+) or the prot onated molecular ions [M+H](+). The presented method allows detection and i dentification of isoquinoline alkaloids in crude methanolic extracts of med icinal plants as Eschscholzia californica CHAM. (Papaveraceae), Hydrastis c anadensis L. (Ranunculaceae), Berberis vulgaris L. (Berberidaceae), Jateorh iza palmata (LAM.) MIERS (Menispermaceae) and Chelidonium majus L. (Papaver aceae).