DIFFERENTIATION OF ISOMERIC C8-SUBSTITUTED AND N2-DEOXYGUANOSINE ADDUCTS OF 2-ACETYLAMINOFLUORENE BY FAST-ATOM-BOMBARDMENT AND TANDEM MASS-SPECTROMETRY

Product-ion studies of source-produced ions corresponding to acetylated and nonacetylated N2- and C8-substituted aminofluorene adducts of deoxyguanosine were conducted to identify specific fragmentation pathways differentiating the isomers and to determine the influence of the acetyl group on the fragmentation of the arylamide modified deoxyguanosine adducts. The collision-induced dissociation spectra of the BH2+ ion and other significant source-produced ions showed no evidence to suggest that ketene loss (deacetylation) resulted in significant alteration of the structure of the adducts. However, other significant ion formation processes, particularly loss of water from the N2-substituted arylamide did appear to require rearrangement, likely involving bond formation between the carcinogen moiety (acetyl group) and the N1 or N2 position of the guanine base. The combined loss of ketene and water constitute a fragmentation pattern specific for the N2-arylamide, 3-(deoxyguanosin-N2-yl)-2-acetylaminofluorene.