期刊
INTERNATIONAL JOURNAL OF MASS SPECTROMETRY
卷 265, 期 2-3, 页码 237-243出版社
ELSEVIER
DOI: 10.1016/j.ijms.2007.02.013
关键词
surface-induced dissociation; ion soft-landing; ion-surface collisions; peptides; self-assembled monolayers; secondary ion mass spectrometry (SIMS); Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS)
Soft-landing of singly and doubly protonated peptide ions onto three self-assembled monolayer surfaces (SAMs) was performed using a novel ion deposition instrument constructed in our laboratory and a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) specially designed for studying collisions of large ions with surfaces. Modified surfaces were analyzed using in situ 2keV Cs+ secondary ion mass spectrometry or ex situ 15 keV Ga+ time-of-flight-secondary ion mass spectrometry (ToF-SIMS). The results demonstrate that a fraction of multiply protonated peptide ions retain more than one proton following soft-landing on the FSAM surface. It is shown that the [M+2H](2+) ions observed in FT-ICR SIMS spectra are produced by desorption of multiply charged ions from the surface, while re-ionization of singly protonated ions or neutral peptides is a source of [M+2H](2+) ions in ToF-SIMS spectra. Differences in neutralization efficiency of soft-landed ions following exposure of surfaces to laboratory air has a measurable effect on the results of ex situ ToF-SIMS analysis of soft-landed ions on SAM surfaces. (C) 2007 Elsevier B.V. All rights reserved.
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