ION TRAP MASS-SPECTROMETRY

Enhanced trajectory control in the quadrupole ion trap, in the presence of helium buffer gas, has brought about enormous improvements in mass range (mass limits in excess of 70 000 Da have been achieved), mass resolution (full width at half-maximum, 1 130000 at m/z 3510), and multistage tandem mass spectrometry (MS)n where n less-than-or-equal-to 13. The compatibility of the ion trap with external ion sources, such as electrospray and atmospheric pressure discharges, has greatly extended the range of application of the ion trap. Brief descriptions of the diagrammatic representation of ion trajectory stability and ion trapping theory precede a review of axial modulation, mass-selective axial ion ejection, ion isolation, collision-induced dissociation, tandem mass spectrometry and dynamically programmed scans. The progress made during the past 3 years in all aspects of ion trap mass spectrometry is reviewed.