DISSOCIATIVE IONIZATION OF THREONINE MOLECULE BY LOW-ENERGY ELECTRONS

Abstract.

Purpose. Present paper aims at obtaining new data on the threonine molecule (C4H9NO3) fragmentation, i.e. formation of ionized products under the influence of low- (<100 eV) energy electrons. Methods. The method of mass spectrometry has been applied using the technique of crossed electron and molecular beams. A magnetic mass spectrometer MI 1201 has been utilized as the mass analyzer allowing the ions to be separated dependent of their mass-to-charge (m/z) ratio. Results. The new data of the threonine molecule (C4H9NO3) electron-impact fragmentation have been obtained. The mass spectrum of the above amino acid molecule has been measured experimentally, the appearance energies for two most intense ion fragments with the m/z=57 and m/z=75 masses have been obtained. Conclusions. Two most stable threonine molecule conformers Thr1 and Thr2 have been analyzed. The possibility of production of the zwitterion ionized molecule has been taken into account. It has been shown that Thr2 ionization results in the initial molecule decay producing the C2H4NO2+ (m/z=74) and C2H5O+ (m/z=45) fragments with the zwitterion form

Keywords: threonine, amino acid, electron, ion, mass spectrum, conformer, dissociation, appearance energy

https://doi.org/10.24144/2415-8038.2020.47.94-102