Aerosol MALDI with a Reflectron Time-of-Flight Mass Spectrometer.

Aerosol matrix-assisted laser desorption/ionization (MALDI) has been combined with a reflectron time-of-flight mass spectrometer for improved mass resolution. A methanol solution of matrix and analyte was sprayed directly into a reflectron time-of-flight mass spectrometer, and the aerosol particles were irradiated and ionized with a frequency-tripled Nd:YAG laser at 355 nm. Mass resolution of over 300 was observed for the peptides bradykinin, angiotensin II, and gramicidin D and for vitamin B(12). This represents a resolution enhancement of approximately 10-fold over that previously reported for aerosol MALDI with a linear time-of-flight instrument.