title: Study on the redox reactions for organic dyes and S-nitrosylated peptide in electrospray droplet impact.
abstract: Reduction of analytes in ionization processes often obscures the determination of molecular structure. The reduction of analytes is found to take place in various desorption/ionization methods such as fast atom bombardment (FAB), secondary ion mass spectrometry (SIMS), matrix-assisted laser desorption/ionization (MALDI) and desorption ionization on porous silicon (DIOS). To examine the extent of the reduction reactions taking place in electrospray droplet impact (EDI) processes, reduction-sensitive dyes and S-nitrosylated peptide were analyzed by EDI. No reduction was observed for methylene blue. While methyl red has a lower reduction potential than methylene blue, the reduction product ions were detected. For S-nitrosylated peptide, protonated molecule ion [M + H](+) and NO-eliminated molecular ion [M - NO + H](+*) were observed but reduction reactions are largely suppressed in EDI compared with that in MALDI. As such, the analytes examined suffer from little reduction reactions in EDI.
authors.affiliation: Clean Energy Research Center, University of Yamanashi, Takeda-4-3-11, Kofu 400-8511, Japan.
authors.forename: Daiki
authors.initials: D
authors.lastname: Asakawa
authors.forename: Kenzo
authors.initials: K
authors.lastname: Hiraoka