Date of Award

Fall 2013

Degree Type


Degree Name

Doctor of Philosophy (PhD)



First Advisor

Scott A. McLuckey

Committee Chair

Scott A. McLuckey

Committee Member 1

Mary J. Wirth

Committee Member 2

Mingji Dai

Committee Member 3

David H. Thompson


Gas-phase ion/ion chemistry involves the interaction of oppositely charged ions inside of the mass spectrometer. During this gas-phase chemistry, particle transfer (i.e., proton and electron) or synthesis can occur at rapid reaction rates. Particle transfer represents a mature area of ion/ion chemistry, while selective covalent modification represents a fairly new area of gas-phase chemistry. Gas-phase covalent chemistry is based on traditional solution phase organic chemistry.

The work demonstrated in this dissertation greatly involves gas-phase covalent and non-covalent Schiff base chemistry on peptide and protein ions. The reagent dianion, 4-formyl 1,3-benzene disulfonic acid, has been used to covalently modify unprotonated primary amines present in peptide and protein ions. In addition, strong non-covalent interactions have also been observed with arginine-containing peptides ions. Studies of their dissociation behavior as well as the nature of their interaction (i.e., covalent versus non-covalent) have been investigated. Application of this Schiff base ion/ion chemistry has been demonstrated on matrix assisted laser desorption/ionization (MALDI)-derived peptide ions. Such Schiff base ion/ion chemistry, whether electrospray or MALDI-derived, can produce complementary or even an increase in structural information. Multiple covalent modifications within one ion/ion encounter have been demonstrated on peptide and protein cations via Schiff base cluster anions. This dissertation also highlights the gas-phase transformation of phosphatidylcholine cations into demethylated phosphatidylcholine anions, which provides an increase in structural information upon activation. As a whole, gas-phase covalent and non-covalent ion/ion chemistry represents a promising new area for identifying and characterizing biological analytes.