[Study of energy characteristics of 5-fluorouracil analogs by photoionization mass-spectrometry].

The fragmentation pathways of N-1-alkoxyalkyl derivatives of 5-fluorouracil and various analogues of an antitumor drug ftorafur have been examined using a mass-spectrometry technique. The ionization and appearance energies for major ions of the compounds under study have been determined on the basis of the ionization efficiency curves obtained using photoionization mass-spectrometry. Different transport forms of 5-fluorouracil have been demonstrated to be similar in the stability of their pseudoglycosidic C-N bond.