Ionization effects in molecular depth profiling of trehalose films using buckminsterfullerene (C60) cluster ions

C. Lu, A. Wucher, Nicholas Winograd

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Salts play a mysterious role in desorption mass spectrometry, especially in biological samples.1 We used trehalose films doped with a peptide as a well defined model system to investigate the ionization effects in organic molecular depth profiling. Sodium salts at 1% level were added into the solution used to produce the trehalose films, and depth profiles were obtained with a C 60 ion source. The results show that the protonated molecular ion signal from the peptide and the quasimolecular ion signal of trehalose are significantly suppressed by the addition of salts, whereas the signals representing salt clusters and salt adducts of trehalose are formed in both positive and negative modes. The formation of protonated molecular ions is found to correlate with the ratio between protonated and bare water ions, suggesting that the latter can be used as an indicator for the accumulation of protons liberated by the ion bombardment. In experiments where no salt was added, it is shown that the surface variation of the protonated molecular ion signal strongly depends upon the water content of the trehalose film.

Original languageEnglish (US)
Pages (from-to)99-102
Number of pages4
JournalSurface and Interface Analysis
Volume43
Issue number1-2
DOIs
StatePublished - Jan 1 2011

Fingerprint

buckminsterfullerene
Fullerenes
Trehalose
Depth profiling
Ionization
Salts
Ions
salts
ionization
molecular ions
ions
Peptides
peptides
Ion sources
Protein Sorting Signals
Ion bombardment
ion sources
Water content
adducts
moisture content

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

Cite this

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abstract = "Salts play a mysterious role in desorption mass spectrometry, especially in biological samples.1 We used trehalose films doped with a peptide as a well defined model system to investigate the ionization effects in organic molecular depth profiling. Sodium salts at 1{\%} level were added into the solution used to produce the trehalose films, and depth profiles were obtained with a C 60 ion source. The results show that the protonated molecular ion signal from the peptide and the quasimolecular ion signal of trehalose are significantly suppressed by the addition of salts, whereas the signals representing salt clusters and salt adducts of trehalose are formed in both positive and negative modes. The formation of protonated molecular ions is found to correlate with the ratio between protonated and bare water ions, suggesting that the latter can be used as an indicator for the accumulation of protons liberated by the ion bombardment. In experiments where no salt was added, it is shown that the surface variation of the protonated molecular ion signal strongly depends upon the water content of the trehalose film.",
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Ionization effects in molecular depth profiling of trehalose films using buckminsterfullerene (C60) cluster ions. / Lu, C.; Wucher, A.; Winograd, Nicholas.

In: Surface and Interface Analysis, Vol. 43, No. 1-2, 01.01.2011, p. 99-102.

Research output: Contribution to journalArticle

TY - JOUR

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AU - Lu, C.

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AB - Salts play a mysterious role in desorption mass spectrometry, especially in biological samples.1 We used trehalose films doped with a peptide as a well defined model system to investigate the ionization effects in organic molecular depth profiling. Sodium salts at 1% level were added into the solution used to produce the trehalose films, and depth profiles were obtained with a C 60 ion source. The results show that the protonated molecular ion signal from the peptide and the quasimolecular ion signal of trehalose are significantly suppressed by the addition of salts, whereas the signals representing salt clusters and salt adducts of trehalose are formed in both positive and negative modes. The formation of protonated molecular ions is found to correlate with the ratio between protonated and bare water ions, suggesting that the latter can be used as an indicator for the accumulation of protons liberated by the ion bombardment. In experiments where no salt was added, it is shown that the surface variation of the protonated molecular ion signal strongly depends upon the water content of the trehalose film.

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