Secondary ion mass spectrometry (SIMS) for biomolecular analysis is greatly enhanced by the instrumental combination of orthogonal extraction time-of-flight mass spectrometry with massive gold cluster primary ion bombardment. Precursor peptide molecular ion yield enhancements of 1000, and signal-to-noise improvements of up to 20, were measured by comparing SIMS spectra obtained using Au+ and massive Au4004+ cluster primary ion bombardment of neat films of the neuropeptide fragment dynorphin 1-7. Remarkably low damage cross-sections were also measured from dynorphin 1-7 and gramicidin S during prolonged bombardment with 40 keV Au 4004+. For gramicidin S, the molecular ion yield increases slightly as a function of Au4004+ beam fluence up to at least 2 × 1013 Au4004+/cm 2. This is in marked contrast to the rapid decrease observed when bombarding with ions such as Au5+ and Au9 +. When gramicidin S is impinged with Au5+, the molecular ion yield decreases by a factor of 10 after a fluence of only 8 × 1012ions/cm2. Comparison of these damage cross-sections implies that minimal surface damage occurs during prolonged Au4004+ bombardment. Several practical analytical implications are drawn from these observations.
|Original language||English (US)|
|Number of pages||6|
|Journal||Rapid communications in mass spectrometry : RCM|
|State||Published - 2004|
ASJC Scopus subject areas
- Analytical Chemistry