QIT mass spectrometer

Doroshenko, V.M. Cotter, R.J. Losses of Ions During Forward and Reverse Scans in a QIT Mass Spectrometer and How to Reduce Them. J. Am. Soc. Mass Spectrom. 1997, 8,1141-1146. 

Schwartz, J.C. Jardine, I. High-Resolution Parent-Ion Selection/-Isolation Using a QIT Mass Spectrometer. Rapid Commun. Mass Spectrom. 1992,6,313-317. 

FIGURE 4.5 The five mass spectrometers commonly used for proteomic research, (a) ESI triple-stage quadrupole mass spectrometer (b) ESI quadrupole ion trap (QIT) mass spectrometer (c) MALDI time-of-flight mass spectrometer. 

The quadrupole ion trap (QIT) mass spectrometer consists of three hyperbolic-shaped electrodes arranged in a cylindrical geometry (see Fig. 2.14). By considering its axial geometry, we can move from the classical Cartesian coordinates to the polar ones. In fact, each point of the space inside the trap can be defined by the value of its axial (z) and radial (r) coordinates. If a potential U + Vcos cot is applied at the intermediate electrode and the two end caps are grounded, a mathematical treatment analogous to that done for quadrupole mass filter can be employed. In this case, a and q values can be defined again as... 

In this chapter, we present details of how the compilation of ion-manipulation methodologies in QIT mass spectrometers can eliminate many of the restrictions that limit currently large molecule mass spectrometry. Specifically, we highlight three MS" interrogation schanes that show genuine promise to enable whole protein analysis (i) ETD coupled with CDD (ii) CID and ETD coupled with Proton Transfer and (iii) lA coupled with CID. 

Like quadrupole mass filters, QIT mass spectrometers are compact, simple to operate, relatively inexpensive, and have high scan speed. Because of their small size and low pumping requirements, these instruments have gained wide acceptance for field applications. High efficiency and sensitivity are other hallmarks of ion-trap instruments. An ion trap is also a useful device to conduct multistage MS experiments (MS" with n = 12 has been envisioned) and gas-phase ion-molecule reactions. It can serve as an effective detector for high-resolution... 

The quadrupole ion trap is a device that utilizes ion path stability of ions to separate them by their mass-to-charge ratio (March, 2000). The quadrupole ion trap and the related quadrupole mass filter were invented by Paul and Steinwedel (1953). Quadrupole ion trap (QIT) mass spectrometer operates with a three-dimensional (3D) quadrupole field. The QIT is formed by three electrodes a ring electrode with a donut shape placed symmetrically between two end cap electrodes (Fig. 8.13). 

Figure 9.34 Cross section of a QIT mass spectrometer. This schematic shows a gas-phase sample intro-duoed from a GC and ionized inside the trap by electrons from the filament. (From Niessen, W.M.A. and van der Greet, J., Liquid Chromatography-Mass Spectrometry, Marcel Dekker, Ino., New York, 1992. Used with permission.)...

Fig. 5. Representative peptide mass fingerprint for the 33.2 and 66.6 kDa proteins resulting from an in-gel digestion of the 66.6 kDa gel band obtained by MALDI-TOF mass spectrometry. Peptides marked with an asterisk result from autodigestion products of recombinant trypsin. Peptides labeled with a diamond were selected for MS/MS experiments carried out on a MALDI-QIT/RTOF and a nano-ESI-QIT mass spectrometer.

Summary of the 12 peptides and their amino acid sequences revealed after MS/MS experiments obtained either on a MALDI-QfT/RTOF or on an off-hne nano-ESl-QIT mass spectrometer... 

Isolation of electrosprayed ions may also occur outside of the QIT. Jonscher and Yates built a hybrid linear QMF/QIT mass spectrometer. The QMF was used to filter out all but a 10-Th mass window of ions which contains the analyte miz of interest. The 10-Th mass window of ions was then injected into the QIT. Preliminary results showed a reduction in space-charge effects for the analysis of peptides by using this prefiltering technique. MDS Sciex has taken advantage of this coupling scheme and built a 4000 QTRAP with... 

Several laboratories successfidly coupled the ESI source to a QIT mass spectrometer in the 1990s.Van Berkel, Ghsh, and McLuckey at Oak Ridge National Laboratory were the first to couple an ESI ion source to a QIT in 1990. In 1992, Mordehai and co-workers at Cornell University coupled their own ESI source to the first bench-top QIT (Saturn II , Varian Instruments, Palo Alto, CA, USA) for use in LC and CE studies. Bruker-Franzen of Germany also introduced an ESI/QIT instmment (ESQUIRE ) at that time. ThermoFisher Corporation introduced an ESI/QIT mass spectrometer (LCQ ) in 1995. In 2002, Hager at MDS Sciex described the first ESI LQIT system. ... 

Figure 9.12. (a) External MALDI/QIT mass spectrometer with fiber-optic delivery of the laser light. (Reprinted with permission from Jonscher, K. Currie, G. McCormack, A. L. Yates, J.R. HI. Rapid Common. Mass Spectrom. 1993, 7, 20-26.) (b) Schematic of aerosol generator, matrix applicatm, and aerosol ion trap mass spectrometer. (Reprinted with permission from Harris, W. A. Reilly, P. T. A. and Whitten, W. B. Anal. Chem, 2005, 77,4042.) (c) A dual ESI and MALDI LQIT mass spectrometer. (Reprinted with permission from Smith, F. A. Blake, T. A. Ifa, D. R. Cooks, R. G. Ouyang, Z. J. Proteome Res. 2007, 6, 837 45.)... 

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