# Proton transfer reagent cations for ion–ion charge state manipulation of high mass negatively-charged analytes in an electrodynamic ion trap

## TL;DR

This paper explores how to use proton transfer reagents to manipulate the charge of large negatively-charged molecules in an ion trap for better analysis.

## Contribution

The study introduces PFDA as a new reagent for efficient and selective proton transfer in ion traps.

## Key findings

- Protonated PFDA is effective for proton transfer to high mass multiply-charged analytes.
- PFDA shows less ion attachment compared to proton sponge in ion/ion reactions.
- Mild collisional heating can remove PFDA adducts from oligonucleotides.

## Abstract

This work summarizes the criteria for a useful reagent for ion/ion proton transfer in an electrodynamic ion trap with specific emphasis on proton transfer to high mass multiply-charged analyte ions. A readily available and ionizable weak base of relatively high mass meets the criteria. The protonated form of an extensively fluorinated 10-carbon primary amine (1H,1H,2H,2H-perfluorodecylamine, PFDA) is demonstrated to serve as a useful reagent for proton transfer to negatively-charged proteins and oligonucleotides. The behavior of protonated PFDA is compared with that of protonated 1,8-bis(dimethylamino)naphthalene (proton sponge) with respect to the tendency for proton transfer versus attachment in ion/ion reactions with a common multiply-deprotonated protein and a common multiply-deprotonated oligonucleotide. Protonated PFDA showed a lesser tendency for ion attachment than the proton sponge in all cases. Both reagent cations showed a greater extent of attachment to the oligonucleotide anions. Mild collisional heating was shown to be able to extensively remove adducted PFDA from the oligonucleotide. The ability to generate low z and high m/z analyte product ions from highly charged precursor analyte ions using protonated PDFA is illustrated with anions derived from β-galactosidase, GroEL, and 30S E. coli ribosome particles.

This work summarizes the criteria for a useful reagent for ion/ion proton transfer in an electrodynamic ion trap with specific emphasis on proton transfer to high mass multiply-charged analyte ions.