Internal energy of MALDI-generated ions


Ioan Marginean, Guanghong Luo, Louise Ye, and Akos Vertes. Department of Chemistry, George Washington University, 725 21-st Street, N.W, Washington, DC 20052
Using the survival yield method, we have demonstrated that the internal energy transferred from MALDI matrixes to analytes depends on the nature of both. The used thermometer molecules are not typical analytes because they exist as preformed ions in the sample. Extending these measurements to small peptides (e.g., leucine enkephalin) is hindered by the presence of competing reactions. Based on the measured survival yields of the peptide molecular ions, we estimate the rate coefficients for each fragmentation reaction. The rate coefficients are evaluated with RRKM theory for different values of internal energy deposited into the analyte molecular ion. Preliminary results indicate that for small peptides more energy is transferred by CHCA than by DHB, - a clear departure from the results for the ionic thermometer molecules.

7:00 PM-9:00 PM, Sunday, March 23, 2003 Convention Center -- Hall G, Poster

Division of Analytical Chemistry
The 225th ACS National Meeting, New Orleans, LA, March 23-27, 2003