Psorospermum febrifugum was examined using tandem ms for the presence of 3',4'-deoxypsorospermin-4'-chloro-3'-ol and psorospermin. Collision-induced dissociation at both high and low energy is used to bring about fragmentation. Daughter spectra were interpreted to reveal characteristic fragmentations for both compounds. Examination of the authentic compounds, various extracts of the plant root, and the plant root material itself established that psorospermin occurs naturally in the plant. The data also suggest the presence of the chlorohydrin in the root, as well as establishing its presence in the root extracts. The detection of neutral compounds in complex mixtures by tandem ms is facilitated if comparisons can be made between spectra resulting from different methods of ionization and excitation.