Elucidation of the dissociation pathways of electro-ionized estrone

With the future aim of using gas chromatography coupled with mass spectrometry to characterize the transformation products of estrone submitted to UV-photolysis or to waste water treatment plants, an interpretation of the electron impact mass spectrum of estrone is presented. Fragmentation mechanisms are proposed on the basis of high-resolution measurements performed with a magnetic sector analyzer. Multiple-stage mass spectrometry experiments were carried out using an ion trap mass spectrometer. The structures proposed for product ions were confirmed by the m/z shifts observed in the estrone-d₄ and estrone methyl ether electron ionization mass spectra. If the formation of some of the most abundant ions may easily be explained by α-cleavages and retro-Diels-Alder type re-arrangements, complex mechanisms need to be considered to rationalize the formation of others. Isotope labelling allows discrimination of isobaric ions.