Introduction to the Quadrupole Ion Trap

The quadrupole ion trap (QIT) creates a three-dimensional RF quadrupole field to store ions within defined boundaries. Its invention goes back to 1953, [103-105] however, it took until the mid-1980s to access the full analytical potential of quad-mpole ion traps. [137-140] The first commercial quadmpole ion traps were incorporated in GC-MS benchtop instruments (Finnigan MAT ITD and ITMS). Electron ionization was effected inside the trap by admitting the GC effluent and a beam of electrons directly into the storage volume of the trap. Later, external ion sources became available, and soon a large number of ionization methods could be 

Note Paul himself preferred to call the device lonenkdfig (ion cage) rather than the nowadays accepted term quadmpole ion trap because it does not actively act to catch ions from outside. The acronym QUISTOR derived from quadrupole ion store was also widespread in use. 

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