Liquid chromatographic electrospray mass spectrometric analysis of Coptidis Rhizoma

Seven protoberberine alkaloids from Coptidis Rhizoma were separated on a Cosmosil 5C18-MS column (5 mu m, 250x4.6 mm I.D.) using ammonium acetate buffer (isocratic) or ammonium acetate-sodium dodecyl sulfate buffer (gradient) with UV and electrospray ionization mass spectrometric (ESI-MS) detection. Selected-ion monitoring was used to resolve the compounds in an overlapped peak and collision-induced dissociation reaction was used to obtain structural infomation of individual components. By use of this LC-UV-ESI-MS method, these protoberberine alkaloids (berberine, palmatine, coptisine, epiberberine, jatrorrhizine, columbamine and berberastine) in a crude extract of Coptidis Rhizoma can be easily separated and identified within 50 min.