Mass Spectrometry in Systems Biology - Systems Biology: Networks, Models, and Applications - page 5

Figure 1.1 ( continued ) (c) Quadrupole ion trap constrains ions into the mass
analyzer that are then ejected to a detector based on their m / z values.
Essentially a single mass analyzer, ion trap can also function as a tandem
instrument by successively concentrating, fragmenting, and analyzing ions
(a process called tandem-in-time) in the physical mass analyzer. (d) In an ion
cyclotron resonance cell, trapped ions rotate with a specific frequency that is
proportional to their mass-to-charge ratio. (Reprinted, with permission, from
the Annual Review of Biophysics and Biomolecular Structure, vol. 33, © 2004
Annual Reviews, www.annualreviews.org.)
opposite polarity. Quadrupole mass filter operates in a mass-selective
stability mode: by varying the amplitudes of RF and DC potentials,
quadrupole selects only the m / z value that will have a stable trajectory
through the filter and arrive at the detector, while all the other m / z
values will have unstable trajectories and be removed from the filter.
Usually, quadrupole mass analyzer has a mass accuracy of 300 ppm.