Infrared laser isolation of ions in Fourier transform mass spectrometry

A new method for isolating ions for tandem mass spectrometry analyses in Fourier transform mass spectrometry is illustrated. The method employs an infrared laser to dissociate completely the undesired ions. The selected ions are excited to an orbit away from the degradative portion of the laser beam. Ion isolation was accomplished and tandem mass spectrometry experiments were performed on model oligosaccharides and compounds from biological samples.