Orbitrap

An orbitrap is an ion trap mass analyzer consisting of an outer barrel-like electrode and a coaxial inner spindle-like electrode that traps ions in an orbital motion around the spindle. The image current from the trapped ions is detected and converted to a mass spectrum using the Fourier transform of the frequency signal.

History

The orbitrap is a modification of the ion trap developed by Kingdon in the early 1920s. The Kingdon trap consists of a thin central wire and an outer cylindrical electrode. A static applied voltage results in a radial logarithmic potential between the electrodes. In 1981, Knight introduced a modified outer electrode that included an axial quadrupole term that confines the ions on the trap axis. Neither the Kingdon nor the Knight configurations were reported to produce mass spectra. Invention of Orbitrap analyzer and its proof-of-principle by Makarov at the end of 1990-s started a sequence of technology improvements which resulted in a commercial introduction of this analyzer by Thermo Fisher Scientific as a part of hybrid LTQ Orbitrap instrument in 2005.