Post-source decay production studies of aniline and methylaniline adducts of deoxyguanosine Original Research Article

Matrix-assisted laser desorption ionization (MALDI) and post-source decay (PSD) are used to study the product ion formation processes of the BH2+ ions of three different arylamine adducts of deoxyguanosine; N-(deoxyguanosin-8-yl)-aniline, N-(deoxyguanosin-8-yl)-2,4-dimethylaniline, and 6-(deoxyguanosin-N2-yl)-2,4-dimethylaniline. Both C8-substituted adducts fragment to lose the guanine C8 carbon and the aniline group to give an ion at m/z 140, whose formation is specific for C8-substituted adducts of guanine. The BH2+ ion derived from N-(deoxyguanosin-8-yl)-2,4-dimethylaniline fragments to form an m/z 165 ion, composed of the guanine base and the nitrogen atom of 2,4-dimethylaniline, specific for guanine attachment to the amine nitrogen. The BH2+ ion derived from N-(deoxyguanosin-8-yl)-aniline does not form m/z 165 because it is not energetically favorable. 6-(deoxyguanosin-N2-yl)-2,4-dimethylaniline fragments to lose the guanine-N2 nitrogen and the 2,4-dimethylaniline group to give an ion at m/z 135, whose formation is a signature for aniline substitution at the N2 position of guanine. Isomers are differentiated with approximately 200 femtomoles of analyte introduced into the TOFMS. The product ion formation processes of these aniline and methylaniline adducts are contrasted with those of other C8- and N2-substituted arylamine adducts of guanine acquired with different MS methods as well.