Orbitrap or orbitrap ( English Orbitrap , orbital ion trap) is a special ion trap that uses a fundamentally new concept of mass analysis, implemented only in the 2000s.
- 1 principle of operation
- 2 History
- 3 Advantages of the method
- 4 disadvantages of the method
- 5 notes
- 6 References
Principle of Operation
The difference from other types of ion traps is the presence of a central electrode of a special shape, to which a negative potential is applied, as well as the absence of magnetic fields (as in double-focusing MS and ion-cyclotron resonance) and radio frequencies (as in a quadrupole or quadrupole ion traps).
The method is based on a symmetric static electric field between the external and internal electrodes.
Ions are introduced at a relatively high speed perpendicular to the central electrode and begin to oscillate around it with a constant path. The oscillation frequency can in principle be used to control the ratio of mass to charge of circulating ions. Although the radial and angular frequencies depend on m / z, the harmonic oscillation of ions along the axis of the electrode is independent of these frequencies. When the voltage across the electrode changes, ions with a specific m / z value are ejected from the ion trap and detected by an electron multiplier, or their mass spectrum is recorded.
Ions also oscillate in the z direction, like ion cyclotron resonance. Unlike the latter, for Orbitrap it is not necessary to detect ions in the z direction.
Accordingly, there are two types of mass analysis:
a) Fourier transform mode — the ion flux is induced towards the external electrode (perpendicular to the central electrode). Ions are detected by the induced image of the current on the external electrodes (as in the ion-cyclotron resonance MS), using the Fourier transform, frequencies corresponding to different m / z are extracted and converted to the mass spectrum.
b) mass selective instability mode: by means of an applied voltage, ions move along the axis of the central electrode. In this case, only ions with a specific mass to charge ratio are detected.
In the Russian version, this method is also called the "Orbital ion trap."
The theory of this mass analyzer was developed by a group of employees of the SPbSPU of the Radio Physics Department under the guidance of prof. Yuri Konstantinovich Golikov, and the technical implementation of the device was carried out by Russian physicist Alexander Makarov , working in Germany, in Bremen, at Thermo Fisher Scientific. Orbitrap devices have been available for commercial use since 2005.
- high resolution - up to 1,000,000 FWHM   (due to the accuracy of installation and stability of the electric field).
- compatible with continuous separation methods
- Detected mass range up to 50,000
- High accuracy: 1-2ppm
- Non-destructive determination of ions
- Possibility of tandem mass spectrometry
- High ion capacity => greater measurement accuracy, wider dynamic range and m / z range
- The need to maintain very low pressure 10 -10 Torr
- The most stable power supply
- Orbitrap Fusion ™ Tribrid ™ Mass Spectrometer . Date of treatment March 26, 2016.
- Eduardo M. Schmidt, Marcos A. Pudenzi, Jandyson M. Santos, Celio FF Angolini, Rosana CL Pereira. Petroleomics via Orbitrap mass spectrometry with resolving power above 1,000,000 at m / z 200 // RSC Advances. - 2018 .-- Vol. 8 , iss. 11 . - P. 6183-6191 . - ISSN 2046-2069 . - DOI : 10.1039 / c7ra12509g .