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

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-dimethylanile and 6-(deoxyguanosin -N-2-yl)-2,4-dimethylanile. Both C8-substituted adducts fragment to lose th e 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 d erived from N-(deoxyguanosin-8-yl)-2,4-dimethylaniline fragments to form an mit 165 ion, composed of the guanine base and the nitrogen atom of 2,4-dim ethylaniline, specific for guanine attachment to the amine nitrogen; The BH 2+ ion derived from N-(deoxyguanosin-8-yl)- aniline does not form mit 165 b ecause it is not energetically favorable. 6-(deoxyguanosin-N-2-yl)-2,4-dime thylaniline fragments to lose the guanine-N-2 nitrogen and the 2,4-dimethyl aniline group to give an ion at m/z 135, whose formation is a signature for aniline substitution at the N-2 position of guanine. Isomers are different iated with approximately 200 femtomoles of analyte introduced into the TOFM S. The product ion formation processes of these aniline and methylaniline a dducts are contrasted with those of other C8- and N-2-substituted arylamine adducts of guanine acquired with different MS methods as well. (C) 1999 El sevier Science B.V. All rights reserved.