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Infrared laser desorption and ionization of polypeptides from a polyacrylamide gel
Author(s) -
BaltzKnorr Michelle,
Ermer David R.,
Schriver Kenneth E.,
Haglund Richard F.
Publication year - 2002
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.295
Subject(s) - chemistry , analyte , desorption , ionization , picosecond , analytical chemistry (journal) , infrared , matrix assisted laser desorption electrospray ionization , matrix assisted laser desorption/ionization , mass spectrometry , soft laser desorption , laser , ion , electron ionization , chromatography , adsorption , optics , organic chemistry , physics
We observed direct desorption and ionization of angiotensin II and bovine insulin from a frozen polyacrylamide gel without the addition of an exogenous matrix, using picosecond pulses from a tunable, mid‐infrared free‐electron laser tuned to strong absorption bands of the gel. At 5.7, 5.9, 6.1 and 6.3 µm we were able to desorb and ionize both analyte molecules, with the strongest analyte signal generated at 5.9 µm. However, no analyte signal was observed at 5.5 µm. Consistent with a previous report, we did not observe ions of either polypeptide at 2.9 µm, in spite of strong overall absorption. We discuss the implications of this wavelength‐dependent ionization, including possible ablation mechanisms and energy partitioning between competing vibrational modes. Copyright © 2002 John Wiley & Sons, Ltd.