Laser-induced desorption of proteins

Laser-induced desorption mass spectrometry has been applied to a number of proteins in the mass range 5000–150 000 u. The beam from an excimer-laser-pumped dye-laser at 266 nm has been focused to a spot of about 50 μm in diameter with irradiances in the 107W/cm2 region. A linear time-of-flight mass spectrometer has been used for mass spectrometric measurements, where positive and negative secondary ions of large proteins have been studied. The effect of different experimental parameters on the protein ion-signal intensities are discussed.