3D QIT

Interaction with electromagnetic fields three-dimensional quadrupole ion trap (3D QIT) analyzers... 

The 3D QIT instruments have played and still play a revolutionary role in high-throughput mass spectral analyses. They are literally work horses that can operate in a 24/7 mode. Instrument maintenance is easy and not time-consuming. Qne disadvantage is that usually oidy unit resolution is achievable, but this drawback is overshadowed by the easy use for tandem MS/MS experiments (i.e., structural investigation, including, e.g., peptide sequencing that is fundamental for proteomics studies). 

Fig. 26. Tandem MS/MS spectra of protonated (V-acetyl OMe proline obtained using different ion-activation methods and instruments, such as gas-phase collisional activation in (a) a Thermoelectron (Finnigan) LCQ classic 3D QIT instrument, (b) a Thermoelectron (Finnigan) triple quadrupole (QQQ) instrument, and (c) surface-induced dissociation (SID) in a Micromass Q-TOF instrument.

The ion trap is a device that utilizes ion path stability of ions for separating them by their m/z [53]. The quadrupole ion trap and the related quadrupole mass filter tvere invented by Paul and Steinwedel [57]. A quadrupole ion trap (QITor 3D-IT) mass spectrometer operates with a three-dimensional quadrupole field. The QIT is formed by three electrodes a ring electrode with a donut shape placed symmetrically between two end cap electrodes (Fig. 1.20). 

QIT The quadrupole ion trap (QIT) utilizes a cylindrical ring and two end-cap electrodes to create a three-dimensional (3D) quadrupolar field for mass analysis. These instruments are capable of selectively trapping or ejecting ions and are often used for the sequential fragmentation and analysis experiments of product ion MS/MS. Also known as a 3D trap due to the configuration (March, 1997). 

MS" A series of n steps in which m/z selection is performed. MS" can be conducted by linking a series of mass analyzers, each of which performs one selection step, or more commonly by using ion-trapping instruments such as QITs (2D or 3D) or FTICR. 

Historically, the first ion traps were 3D ion traps. They were made up of a circular electrode, with two ellipsoid caps on the top and the bottom that creates a 3D quadrupolar field. These traps were also named quadrupole ion traps (QITs). To avoid confusion, this term should not be used but should be replaced preferably with Paul ion trap. The acronym QUISTOR derived from quadrupole ion storage is also largely used but not recommended. 

Relatively new mass analyzers with very high resolution include the quadrupole ion trap (QIT) and the Fourier-transform ion cyclotron resonance (FTICR) instruments. In both analyzers, ions are trapped in a 3D field, and are analyzed once trapped. In Table 15.3, the mass analyzers described here are compared. The combination of MS with other analytical techniques is also very common MS has been widely used following chromatographic separations, for mass analysis. 

Although 3D traps have been extensively used, during the early to mid-2000s, for structural elucidation of metabolites, overall a slower scan rate compared to TOF mass analyzers, in combination with limited ion capacity and trapping efficiency are the limitations associated with the QITs for becoming the mass analyzer of choice for quantitative/qualitative bioanalysis. Most importantly, 3D traps can only simulate SRM by acquiring full-scan MS data, true SRM scan modes can only be... 

Ion Trap The first demonstration of full-scan MS/MS data for MALDI imaging was obtained with a three-dimesional (3D) quadrupole ion trap (QIT) (Troendle et al., 1999 Garrett et al., 2005). These experiments were performed on an instrument constructed at the University of Florida and clearly demonstrated the critical role of MS/MS for imaging small molecules in tissue. The use of ion traps for MSI has been reviewed (Garrett and Yost, 2009). The QIT can trap and store ions from a pulsed laser desorption event in contrast, quadrupole mass spectrometers and other scanning instruments are... 

An Agilent 3D CE coupled to a Bruker Esquire 3(X)(F quadrupole ion trap (QIT)-MS with a sulfobutylether-cyclodextrin-ammonium acetate separation buffer at pH 6.9 is used to analyze TNT, TNB, RDX, HMX, and CL-20 [199]. CE coupled to a mass spectrometer with ESI enables better resolution than LC separation and thus enhanced identification of moderate polarity nitra-mine explosives and their degradation products from soil and water samples. 

The 2D- and 3D-Quadrupole Field Ion Trap (QIT) Scan Functions and Timing... 

Figure 9.1. The four mass analyzers discussed in this chapter (a) A 2D-quadrupole field mass filter (QME9. (b)A 3D-quadruople field ion trap (QIT). Parts a and b are ftom Paul, W. Steinwedel, H. German Patent 944,900,1956.

Plotting and overlapping the solutions to the Mathieu equation in a, q) space for the r and z dimensions forms the QIT stability diagram. A portion of the stability diagram including the solutions where = 0 is shown in Figure 9.3b. The Mathieu parameters, a and q, are indicative of the stability and motion of an ion in the 3D-quadrupole field. 

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