AVS 50th International Symposium
    Applied Surface Science Wednesday Sessions
       Session AS-WeP

Paper AS-WeP8
The Systematic Study of Ga TOF SIMS High Mass Molecular Ion Registration, Composition and Fragmentation of Selected Peptide Hormones on Silver Substrate

Wednesday, November 5, 2003, 11:00 am, Room Hall A-C

Session: Poster Session
Presenter: A. Wilkerson, College of William and Mary
Authors: H Chen, College of William and Mary and Incogen, Inc.
A. Wilkerson, College of William and Mary
D. Malyarenko, College of William and Mary and Incogen, Inc.
E. Tracy, Applied Research Center and College of William and Mary
D. Manos, Applied Research Center and College of William and Mary.
Correspondent: Click to Email
This paper reports the use of Ga+ SIMS to provide imaging simultaneously with high sensitivity and specificity for peptide hormone registration. Although this technique is developed for high molecular weight organic polymers on silver and gold, no similar systematic quantitative studies are reported for biopolymers. We report high resolution spectra obtained by ToF-SIMS for molecular ions of Vasopressin II, Human Angiotensin and Somatostatin adsorbed on silver substrate. Characteristic positive high-mass parent peaks and adducts have been identified. The mass resolution exceeds 2000 for all three peptides. The dependence of the yield for the parent peak on solution concentration has been studied for Angiotensin. Parent peak intensities comprise from 1 to 15 % of the intensity for identifiable fragments. Images confirm that the fragmentation is associated with multi-layer formation. Parent peak adducts reproducibly display the anticipated quantitative isotope ratios and are skewed toward high masses. Sodium contamination adducts are registered as well. The images of surface coverage are reported at the parent masses. Unlike MALDI, no multiply charged species, ladder fragmentation or dimers are observed in the intermediate mass range. The low molecular weight peaks (below 200 Da) have characteristic signatures of the amino acid content for the peptides.