Characterization of aconitine‐type alkaloids in the flowers of Aconitum kusnezoffii by electrospray ionization tandem mass spectrometry

The fragmentation mechanism of aconitine‐type alkaloids in the flowers of Aconitum kusnezoffii (FAK) was investigated using electrospray ionization tandem mass spectrometry (ESI‐MS n ) firstly. The analysis of the collision‐induced dissociation (CID) spectra of three purified aconitine standards and six previously reported aconitines indicated that the fragmentation of the protonated aconitines at low‐energy CID follows a similar pathway. The elimination of a C 8 ‐substituent such as an acetic acid or a fatty acid is the dominant fragmentation mode in MS2. Successive losses of CH 3 COOH, CH 3 OH, H 2 O, BzOH, and CO are the main fragmentation pathways of aconitine‐type alkaloids in MS 3 spectra. Based on these features, a rapid method for the direct detection and characterization of alkaloids from an ethanolic extract of FAK is described. All the known aconitum alkaloids are detected and a series of lipo‐aconitines has been found for the first time in this plant. Copyright © 2003 John Wiley & Sons, Ltd.