Mass spectrometry with electron ionization and electrospray ionization have been applied to characterize and differentiate the isomeric ortho-, meta- or para-(E)-bromoalkyloxychalcones 1–15. The difference in the values of µ1–µ5 (i.e. the ratio of abundances of the selected fragment ions to those of the molecular ions) in the series of isomeric chalcones studied and the so-called “in-source” fragmentation induced by increasing cone voltage have been found to be important and reliable indicators differentiating the isomers studied.

Keywords: chalcone, electron ionization, electrospray ionization, isomer differentiation