Orbitrap

Ion trajectories in an Orbitrap mass spectrometer.

The Orbitrap is the latest development in ion trap mass spectrometers with a central, spindle-shaped electrode .

history

Kenneth Hay Kingdon (1894–1982) first considered the measurement concept in the early 1920s. Work on a working prototype of the Orbitrap was published by Alexander Alexejewitsch Makarow in 2000. Technical advancements led to the first commercial device in 2005, which was marketed by Thermo Fisher Scientific as a coupling Linear trap / Orbitrap. The Orbitrap is now available with a linear trap (“LTQ Orbitrap”), quadrupole (“Q Exactive”) or coupled directly to an ion source (“Exactive”).

LTQ Orbitrap

Working principle

A central, spindle-shaped electrode is located in the ion trap . The ions are shot into the orbitrap radially to this electrode and, due to the electrostatic attraction, move in circular paths ( orbits ) around the central electrode. Since the ions are not injected in the center of the chamber, but in a decentralized manner, they vibrate simultaneously along the axis of the central electrode. The frequency of this oscillation generates signals in detector plates, which are converted into the corresponding m / q ratios by Fourier transformation . The principle is therefore similar to the FT-ICR-MS , but works with an electrostatic field instead of a magnetic field. Orbitraps therefore manage without the complex cooling with liquid helium . The mass resolution of orbitraps is only marginally worse than that of an FT-ICR device with a 7 Tesla magnet. The resolution achieved in practice is usually between 80,000 and 280,000.

Web links

Commons : Orbitrap - collection of images, videos and audio files

Planet orbitrap - Homepage of the manufacturer , engl.
Purdue University Orbitrap Page , engl.

Individual evidence

^ KH Kingdon: A Method for the Neutralization of Electron Space Charge by Positive Ionization at Very Low Gas Pressures . In: Physical Review . 21, No. 4, 1923, p. 408. doi : 10.1103 / PhysRev.21.408 .
↑ A. Makarov: Electrostatic Axially harmonic orbital trapping: A high-performance technique of mass analysis . In: Analytical Chemistry . 72, No. 6, 2000, pp. 1156-62. doi : 10.1021 / ac991131p .
^ A. Makarov, E. Denisov, A. Kholomeev, W. Balschun, O. Lange, K. Strupat, S. Horning: Performance evaluation of a hybrid linear ion trap / orbitrap mass spectrometer . In: Analytical Chemistry . 78, No. 7, 2006, pp. 2113-20. doi : 10.1021 / ac0518811 .

[1] KH Kingdon: A Method for the Neutralization of Electron Space Charge by Positive Ionization at Very Low Gas Pressures . In: Physical Review . 21, No. 4, 1923, p. 408. doi : 10.1103 / PhysRev.21.408 .

[Mak1-2] A. Makarov: Electrostatic Axially harmonic orbital trapping: A high-performance technique of mass analysis . In: Analytical Chemistry . 72, No. 6, 2000, pp. 1156-62. doi : 10.1021 / ac991131p .

[Mak2-3] A. Makarov, E. Denisov, A. Kholomeev, W. Balschun, O. Lange, K. Strupat, S. Horning: Performance evaluation of a hybrid linear ion trap / orbitrap mass spectrometer . In: Analytical Chemistry . 78, No. 7, 2006, pp. 2113-20. doi : 10.1021 / ac0518811 .