Orbitrap systems

The FT-ICR method described in Section 2.3.4 suffers only from one weak point It requires magnetic fields with intensities > (or =) 3 Tesla. Consequently, cryomagnets are required, with high costs either for acquirement or for maintenance. The commercial availability of mass spectrometers exhibiting high performances, but low initial cost, modest maintenance cost, and reduced size, is surely of great interest, and the Orbitrap system (Hu et al., 2005) is the answer to this need. 

Moreover, ions could travel much faster in vacuum than in a gas where their velocity is restricted by collisions. For example, ions fly through an evacuated tube of standard TOF MS systems in 20-100 ps, or 1000 times faster than through an IMS drift tube of similar length ( 100 cm). Of course, the feasibility of rapid ion travel in MS does not imply that any MS process must be quick analyses in FTICR, quadrupole trap, and orbitrap systems where ions are stored in circular orbits often last >100 ms, i.e., longer than typical IMS separations. However, the existence of MS techniques placing the usual duration of IMS analyses is (on a logarithmic scale) about halfway between those of MS and condensed-phase methods have crucial implications for practical utility of IMS. 

One of the main applications of both Orbitrap systems and their MALDl ion sources is for the imaging of biological specimens. The Thermo Fisher Scientific... 

The Thermo Scientific ion source can be retrofitted to the LTQ Orbitrap XL line of instruments, while the TransMIT ion source can be retrofitted to the Exactive series instrumentation. The MassTech AP MALDI PDF+ ion source has also been adapted to both hybrid Orbitrap devices, as well as to bench-top Orbitrap systems. 

Li, A.C., Ding, J., Jiang, X., et al. (2009) Two-injection workflow for a liquid chromatography/LTQ-Orbitrap system to complete in vivo biotransformation characterization demonstration with buspirone metabohte identification. Rapid Communications in Mass Spectrometry, 23,3003-3012. 

An Orbitrap system was used with 30 ppm peptide mass tolerance, 0.5 Da MS/MS tolerance, one missed tryptic cleavage for all DB searches. Oxidation on methionine and deamidation on glutamine and asparagine were chosen as a possible modification. 

Amelia Peterson et al, University Wisconsin, Prof Josh Coon group, published first results on the implementation of an EI/CI interface on a hybrid Orbitrap system for ultra-high resolution GC-MS using a GC-Quadrupole-Orbitrap configuration for full scan, SIM, MS/MS and SRM (selected reaction monitoring) at the ASMS conference. 

Figure 4.19 ESI product ion mass spectra of the protonated molecules [M+H]+ of (a) GW1516 (mol wt = 453), and (b) 5-amino-4-imidazolecarboxamLde ribonucleoside (AICAR, mol wt = 258) recorded on an LTQ-Orbitrap system.

Figure 5.13 ESI product ion mass spectrum of the three-fold charged precursor ions [M-i-3H] of m/z 1118 of Geref, measured on an LTQ-Orbitrap system.

Figure 5.15 ESI product ion mass spectra of (a) the six-fold charged precursor ion [M-I-6H] of tn/z 1275 of IGF-1, and (b) the six-fold charged precursor ion [M-r6H] of m/z 1228 of des(l-3)IGF-l, both measured on an LTQ-Orbitrap system.

With recent instrumental development, such as fast LC, fast GC and two-dimensional gas chromatography (GCxGC) and advanced tandem hybrid MS detection systems (i.e., QqTOF, QqLIT, Orbitrap) the analysis of complex mixtures... 

Fig. 1.30 Schematic of the linear ion trap (LIT)-orbitrap (LTQ orbitrap, Thermo). One of the specificities of the system is that the LIT has two detectors. Therefore the LIT can perform various experiments at the same time. Adapted with permission from reference [76].

The Orbitrap-based systems have emerged as the newest option for LC-HRMS. When configured as hybrid linear trap-Grbitrap (LTQ-Orbitrap), the systems are conceptually similar to Q-TOF in that mass analyzer 1 is nominally a unit mass analyzer, and mass analyzer 2 is capable of high resolution. These systems are capable of either LC-HRMS or LC-MS/HRMS operation. A new variant on the commercial Orbitrap, the Exactive, is expected to be released in late 2008. This system, which consists only of the single mass analyzer, has shown promising results in early assessment of quantitation by LC-HRMS (Bateman et al., 2008). 

Commercial LITs were introduced in 2002 as either a stand-alone mass spectrometer (LTQ) [318] or as part of a triple quadrupole (Q-Trap) [319] or in 2005 as part of hybrid tandem mass spectrometers (LTQ-Orbitrap and LTQ-FTICR) [88,90], Application of LTQ-FTICR for metabolism studies has been reviewed by Shipkova et al. [90], In comparison to other mass analyzer types, FTICR-based mass spectrometers are not very popular for metabolite identification studies due to availability of less expensive and more user-friendly LTQ-Orbitrap and Q-TOF-based systems. Another limitation associated with the FTICR-based hybrid mass spectrometers is the TOF effect, which results in efficient trapping of only the high-mass ions [90],... 

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