Quadrupole ion traps

Abstract

The extraordinary story of the three-dimensional radiofrequency quadrupole ion trap, accompanied by a seemingly unintelligible theoretical treatment, is told in some detail because of the quite considerable degree of commercial success that quadrupole technology has achieved. The quadrupole ion trap, often used in conjunction with a quadrupole mass filter, remained a laboratory curiosity until 1979 when, at the American Society for Mass Spectrometry Conference in Seattle, George Stafford, Jr., of Finnigan Corp., learned of the Masters' study of Allison Armitage of a combined quadrupole ion trap/quadrupole mass filter instrument for the observation of electron impact and chemical ionization mass spectra of simple compounds eluting from a gas chromatograph. Stafford developed subsequently the mass-selective axial instability method for obtaining mass spectra from the quadrupole ion trap alone and, in 1983, Finnigan Corp. announced the first commercial quadrupole ion trap instrument as a detector for a gas chromatograph. In 1987, confinement of ions generated externally to the ion trap was demonstrated and, soon after, the new technique of electrospray ionization was shown to be compatible with the ion trap.

Experimental Characterization of Secular Frequency Scanning in Ion Trap Mass Spectrometers

“…Methods of scanning quadrupole-based analyzers can be deduced from the Mathieu parameters a u and q u , which describe the stability of ions in a quadrupolar field [3,4]:…”

A Short Overview of the Components in Mass Spectrometry Instrumentation for Proteomics Analyses

“…The main function of a mass analyzer is to separate the ions according to their m/z ratio [38], basically by their behavior in electric or magnetic fields [39]. Nowadays, there are few types of analyzers widely used analyzers in tandem mass spectrometry experiments, for proteomics analyses: quadrupole, quadrupole ion trap, time of flight and orbitrap.…”

“…Basically it consists of four roods assembled in two pairs, as shown in figure 2A. The first two opposite roods have the same applied voltage, which is different from that of the second two opposite roods establishing a two dimensional quadrupole field in the x-y plane ( Figure 2A) [38]. The mass analysis depends on the radio frequency, and direct current voltages which are applied to the four roods [1].…”

“…Considering the ion population being injected in a quadrupole analyzer, a selection can be made according to their m/z ratio, making some ions to have a stable trajectory in the analyzer, while a considerable number of other ions will not go all the way through (Figure 2A, arrows). The ion path occurs in the z direction, while the attraction and repulsion are occurring simultaneously in the x and y direction ( Figure 2A) [38,42]. If the oscillations of an ion are stable, the ion will continue to drift down the rod assembly and reach the detector.…”

Resonant excitation of trapped molecules in a molecular synchrotron

“…It is a well-established technique for investigating and manipulating the motion of trapped ions and electrons [1][2][3][4] and is used on a regular basis to characterize the trap frequencies of magnetic and optical dipole traps of neutral atoms, including ring traps [5][6][7][8][9]. In this technique, the fields used for confinement are superimposed with a small external field.…”