Instrumentation trapping-mass spectrometer

The Mass Spectrometer Module houses the vacuum system, capillary interface assembly, and ion-trap mass spectrometer in approximately half of the module. Also included are the reagent gas and calibration gas subassembly (a temperature-controlled housing that ensures consistent gas pressures). The other half contains the electronic printed circuit boards, power supplies, and instrument control computer. 

Figure 6.1. Mass spectra of synthetic peptide, FLFQPQRF-NH2. Both spectra were recorded on an ESI ion trap mass spectrometer at different instrument settings (modifications of ion optics and ion-trap parameters).

There are two kinds of Type (2) ion trap mass spectrometers the quadrupole ion trap and the ion cyclotron resonance instruments. 

Fig. 5.9 Design of the chip-based enzyme ESI-MS assay. MS instrument Ion-trap mass spectrometer (LCQ Deca, Thermo Electron). I Sample components/inhibitors injected by flow injection or eluting from capillary HPLC column. E Infusion pump delivering the enzyme cathepsin B. S infusion pump delivering the substrate Z-FR-AMC. Micro-chip design Vrije Universiteit Amsterdam. Micro-chip production Micronit Microfluidics BV (Enschede, The Netherlands).

Fig. 5.15 Analytical set-up for on-line label-free assay based on ESI-MS. MS instrument Ion-trap mass spectrometer (LCQ Deca, Thermo Electron). PI Carrier/HPLC pump. P2 HPLC pump delivering receptor solution. P3 HPLC pump delivering dissociation solution. PA HPLC pump for final LC-MS analysis of released ligands. 1 Mixing union. 2 Microcoil reactor. VI injection valve.

Fig. 5.17 Demonstration of MS-based bioassay functionality using a plant extract. MS instrument Ion-trap mass spectrometer (LCQ Deca, Thermo Electron), (a) MS analysis of pure extract by direct injection onto restricted-access column 2 in the absence of affinity protein, (b) Analysis of the same natural extract spiked with digoxin using the label-free MS assay method as shown in Fig. 5.15.

Fig. 8.1.1 Simple illustrations of a various mass spectrometers, a The triple-quadrupole tandem mass spectrometer (top panel). The middle set of quadrupoles are part of the collision cell (CC) and do not perform mass separation. MSI and MS2 indicate the first and second quadrupole mass separation devices, respectively. The bold arrow shows the path of ions, b Ion-trap mass spectrometer (middle left). The charged sections of the ion trap are not elliptical as drawn, but rather hyperbolic. The diagram is also two-dimensional, whereas the ion trap is three-dimensional. The ion path is such that ions enter the device and are trapped until a specific voltage ejects these ions, c Time of Flight mass spectrometer with a Reflectron (middle left). Ions are separated by the time it takes to pass through the instrument. The Reflectron improves/focuses the ions, d Hybrid Tandem mass spectrometer (bottom). The diagram shows that a quadrupole instrument can be combined with a different type of mass spectrometer, forming a tandem hybrid instrument...

A new generation of linear ion trap mass spectrometers has been developed and exhibits increased performance compared to traditional three-dimensional (3D) ion traps (Hopfgartner et al., 2003 Douglas et al., 2005). A further evolution of the triple-quadrupole family and ion trap class of instruments is the production of the hybrid triple-quadrupole/linear ion trap (QQQ/LIT) platform. Hybrid instruments of this nature allow for operation in space and not just in time when performing MS/MS analysis. This feature allows for increased performance compared to classical ion traps. A powerful combination possible on a hybrid LIT/QQQ instrument is the ability to use highly sensitive and selective precursor ion, constant neutral loss, and multi-MRM as a survey scan for dependent LIT MS/MS. Compared to a simple MS experiment, these comprehensive triple-quadrupole and LIT modes can be more complex to setup. 

As mentioned in the previous section, triple-quadrupole instruments are very good at finding low levels and structurally related compounds in the presence of biological matrices as well as being the gold standard technique for quantitation. Ion trap mass spectrometers, on the other hand, have the capabilities to obtain high-sensitivity full-scan MS and MS/MS spectra therefore, they are widely used for qualitative analysis, such as structural elucidation and unknown identification. For complete metabolite identification, it is important to have both the sensitivity and selectivity of triple-quadrupole instruments and the full-scan data quality of ion traps. 

Similar experiments have previously been performed separately using a triple-quadrupole or an ion trap mass spectrometer for quantitation followed by accurate mass measurements with a Q-TOF mass spectrometer. With the introduction of the LTQ-FTMS instruments, all the data can be gathered quickly and easily with one experimental setup, and the variations in observed metabolic profiles introduced by... 

Mass analyzer is the term given to the part of the mass spectrometer that discriminates between ions on the basis of their mass-to-charge ratios (m/z). The most common instruments currently in use with MALDI and ESI sources for the analysis of carbohydrates are quadrupole-based instruments, TOF mass spectrometers, and ion-trapping instruments (ion cyclotron resonance and quadrupole ion-trap designs). 

A significant difference between the two types of trapping instruments is that in the ion trap mass spectrometers, ions are expelled from the trap to be analysed. Hence they can be observed only once at the end of the process. In FTMS, they can be observed non-destructively, and hence measured at each step in the sequential fragmentation process. 

Another MS/MS instrument, the Q-TRAP mass spectrometer, merges a triple quadrupole with an IT mass spectrometer, combining high sensitivity with high selectivity (Le Blanc et ah, 2003). Q-TRAP instruments have been used to characterize, and in some cases quantify, ellagitannins in red wine (Stark et ah, 2010), anthocyanins in red... 

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