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Updated: May 5, 2026

Characterization of Synthetic Polymers via Matrix Assisted Laser Desorption Ionization Time of Flight MALDI-TOF Mass Spectrometry
Published on: June 10, 2018
Gas-Phase cationization and protonation of neutrals generated by matrix-assisted laser desorption
B H Wang1, K Dreisewerd, U Bahr
1Institute of Medical Physics and Biophysics, University of Muenster, Muenster, Germany.
Abstract:
The ionization mechanisms involved in matrix-assisted ultraviolet laser desorption/ionization (MALDI) were studied with a time-of-flight mass spectrometer. When protonated or cationized quasimolecular ions generated by MALDI are not extracted promptly, their abundance is a function of the delay time between laser irradiation and ion extraction, maximizing at an optimum delay time (DTM) of a few hundred nanoseconds. The ion abundance at DTM exceeds that of prompt extraction by a factor of 2 or more. Increasing the cation density near the sample surface reduces the DTM, whereas increasing the desorption laser irradiance has the opposite effect. The enhancement suggests extensive gas-phase ion-molecule reactions after irradiation by the desorption laser has ceased.
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