Orbitrap

The concept of electrostatically trapping ions in an orbit around a central spindle was developed by Kenneth Hay Kingdon in the early 1920s.

In 1981, Knight introduced a modified outer electrode that included an axial quadrupole term that confines the ions on the trap axis.

[5] Golikov later remarked "Based on my ideas, analytical instruments with record parameters were built, but unfortunately not in Russia, but abroad.

"[6][8] Alexander Makarov's effort in commercializing Orbitrap analyzer at the end of the 1990s[1] required a number of innovations such as image current detection,[9] C-trap for ion injection,[10] and other technology improvements which resulted in the commercial introduction of this analyzer by Thermo Fisher Scientific as a part of the hybrid LTQ Orbitrap instrument in 2005.

In addition, the ions also move back and forth along the axis of the central electrode so that their trajectories in space resemble helices.

All commercial Orbitrap mass spectrometers utilize a curved linear trap for ion injection (C-trap).

In principle, coherent axial oscillations of ion rings could be excited by applying RF waveforms to the outer electrode as demonstrated in[13] and references therein.

Axial oscillations of ion rings are detected by their image current induced on the outer electrode which is split into two symmetrical pick-up sensors connected to a differential amplifier.

The Orbitrap differs from FTICR-MS by the absence of a magnetic field and hence has a significantly slower decrease of resolving power with increasing m/z.

[14] The Orbitrap analyzer can be interfaced to a linear ion trap (LTQ Orbitrap family of instruments), quadrupole mass filter (Q Exactive family) or directly to an ion source (Exactive instrument, all marketed by Thermo Fisher Scientific).