Mass spectrometric studies of selected coumarins and psoralens. I—negative ions

An investigation of the negative‐ion chemistry of 13 coumarin and three psoralen compounds is reported. Negative‐ion chemical ionization was effected using O −˙ and OH − as the reagent ions; it was found that O −˙ leads preferably to [M – H + O] − whereas OH − mainly furnishes [M – H] − . The results of metastable anion fragmentation and collision‐induced dissociation of mass‐selected anions are presented.