Mass spectrometry analyzers orbitrap

In principle, it would be possible to perform multistage mass spectrometry like in an ICR analyzer although with no gas CID would of course not be possible, but other dissociation methods could be employed. There might, however, be technical issues. At the time of writing, fragmentation is performed in the linear QIT preceeding the orbitrap in Thermo Fischer Scientific s instrument. Both pulsed and continuous ion sources can be employed. There are several ion sources that can be employed with Thermo Fischer Scientific s orbitrap. 

Schmid, D. G., Grosche, P., Bandel, H., and Jung, G. (2000). FTICR-mass spectrometry for high-resolution analysis in combinatorial chemistry. Biotechnol. Bioeng. 71 149-161. Scigelova, M., and Makarov, A. (2006). Orbitrap mass analyzer—Overview and applications in proteomics. Proteomics 6 (Suppl. 2) 16-21. 

Recent innovations in mass spectrometry have provided incorporation of two, three, and four analyzers into commercially available tandem instruments. In addition, different mass analyzers may be combined to form a hybrid mass spectrometer such as the quadrupole-TOF (Q-TOF). Various types of tandem mass spectrometers include the quadruopole-TOF, time-of-flight-time-of-hight (TOF-TOF), triple-quadrupole, and Orbitrap-FTICR configurations. 

The fundamental process of MS/MS (in a tandem mass spectrometer) is that a particular precursor ion is fragmented (decomposed) into a smaller product ion accompanied by the loss of a neutral fragment. The precursor ion is usually selected in the first analyzer, reacted by some means in a specialized chamber (see below) to produce product ions that are then separated in a second analyzer, hence the terms mass spectrometry/mass spectrometry and tandem mass spectrometry. As discussed later, precmsor and product ion analyses can be separated in space, using sequential analyzers that are either of the same type or in hybrid configurations, or separated in time in the latter the two analytical processes are carried out sequentially, within the same analyzer. There are several MS/MS instrument combinations, including QqQ, QIT, LIT, TOF/TOF, QTOF, LlT-orbitrap, and LIT-FT-ICRMS. 

Tandem mass spectrometry (MS/MS) is very useful for the amino acid sequencing of peptides, and has been used widely in both protein biochemistry and pro-teomics to identify proteins, to deduce the sequence of a peptide, and to detect and locate post-translational modifications. Until around a decade ago, the concept of amino acid sequencing by MS-technologjes was synonymous with ESI-MS/MS, but today MALDI-MS/MS techniques are implemented in high-performance instruments such that the quality of MALDI tandem mass spectra is comparable with that of ESI-MS/MS spectra. Currently, MALDI tandem mass spectrometers exist in a number of geometries, including TOF-TOF, Q-TOF, ion trap and orbitrap analyzers that each provide unique analytical features for the sequencing of peptides and proteins by MS/MS (details of the instrumentation for different types of MS/MS are provided in Chapter 2). 

It is clear that mass spectrometry imaging has great potential as a comprehensive analysis technique for endogenous peptides, particularly with a hardware configuration as evaluated in this chapter, where MALDI produced ions are analyzed in an ion trap - Orbitrap hybrid instrumentation. A single experiment can provide high mass accuracy data in combination with the spatial distribution of peptides in the tissue sample. With MS/MS experiments the molecular identity (accurate mass measurements complemented with MS" sequence data) can be confirmed firom a single or few scans only and from a few laser shots in total. 

Makarov, A. Theory and practice of the orbitrap mass analyzer. In Proceedings of the 54th ASMS Conference on Mass Spectrometry and Allied Topics, Seattle, WA, May 28-June 1, 2006. 

Thevis, M., Makarov, A.A., Homing, S., and Schanzer, W. (2005) Mass spectrometry of stanozolol and its analogues using electrospray ionization and collision-induced dissociation with quadrupole-linear ion trap and linear ion trap-orbitrap hybrid mass analyzers. Rapid Communications in Mass Spectrometry, 19,3369-3378. 

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