APPLICATION NOTE: The Evolution of Ion Trap Mass Spectrometry

摘要

Quadrupole ion trap mass spectrometers, commonly called "ion traps", have a long, rich history as extremely sensitive analytical instruments that identify compounds and their molecular structure based on their molecular weight. The capability to accumulate and manipulate ions in time and subsequently perform selective mass ejection to an external electron multiplier gives ion traps unique abilities and attributes. Perhaps most notably, ion traps can carry out multiple stages of ion dissociation and ion/molecule reactions with very high efficiency, enabling routine detection and identification of low level analytes. In the late 1970's, the development of the first commercially available ion trap detector for gas chromatography, the ITD 700, began at Finnigan Corporation (now Thermo Fisher Scientific). The instrument was a direct result of the insight by George Stafford, who recognized that the previous mode of operating ion traps was inefficient, since the quadrupole ion trap was being utilized as if it was a quadrupole mass filter (QMF). A QMF, the device used in single quadrupole and triple quadrupole mass spectrometers, permits only ions of one mass-to-charge (m/z) ratio to pass through to a detector at any given time. The quadrupole ion trap was being used to selectively accumulate ions in a single region of m/z and pulse them to a detector and then analyze the next m/z region successively until an entire spectrum was constructed. Stafford realized that ions of a range of m/z could be accumulated at the same time and each range of m/z ejected to the detector in a mass-selective fashion, such that an entire spectrum could be acquired in a short period of time [1].