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.