REACTIVE COLLISIONS IN QUADRUPOLE CELLS .3. H D EXCHANGE-REACTIONS OFPROTONATED AROMATIC-AMINES WITH ND(3)/

The H/D exchange reactions of a variety of protonated aromatic amines with ND3 in the collision cell of a hybrid BEqQ tandem mass spectromet er have been studied. The MH+ ions were prepared by CH4, i-C4H10, and NH3 chemical ionization (CI) and, for some amines, by fast-atom bombar dment (FAB). Evidence is presented that the kinetic energy of the inci dent ion as well as its internal energy must be dissipated by nonexcha nging collisions before exchange occurs; once deactivated the MH+ ions exchange efficiently, which leads, in most cases, to [MH]+ d(x) ions in which all active hydrogens have been exchanged. The MH+ ion of 1,3- phenylenediamine formed by gas-phase CI exchanges only very slightly w ith ND3 whereas a significant fraction of the MH+ ions formed by FAB e xchange efficiently. This difference is rationalized in terms of domin ant formation of the ring-protonated species in gas-phase CI reactions and significant formation of the N-protonated species by FAB with onl y the N-protonated species exchanging efficiently. Similar, although l ess pronounced, differences are observed for the MH+ ion of m-anisidin e. In a number of cases apparent exchange of aromatic hydrogens also i s observed. Evidence is presented for the interchange of ring and amin e hydrogens in protonated aromatic amines and it is suggested that onl y the N-protonated species undergoes significant exchange with ND3.