Linear trap quadrupole mass

One of the latest mass analyzer is the linear-trap quadrupole (LTQ) Orbitrap mass spectrometer. In this, the commercial LTQ is coupled with an ion trap, developed by Makarov [73, 74]. Due to the resolving power (between 70000 and 800000) and the high mass accuracy (2-5 ppm), Orbitrap mass analyzers, for example, cab be used for the identification of peptides in protein analysis or for metabolomic studies. In addition, the selectivity of MS/MS experiments can be greatly improved. However, the coupling is not useful with UHPLC for rapid chromatographic pre-separation, as the data acquisition rate is too low for a reproducible integration of the narrow signals produced with UHPLC. 

TABLE 16.2 ESI and APCI Method Parameters for Linear and Ion Trap Quadrupole Mass Spectrometer Analysis by Direct Infusion... 

In mass spectrometers, ions are analysed according to the ml7. (mass-to-charge) value and not to the mass. While there are many possible combinations of technologies associated with a mass-spectrometry experiment, relatively few forms of mass analysis predominate. They include linear multipoles, such as the quadrupole mass filter, time-of-flight mass spectrometry, ion trapping forms of mass spectrometry, including the quadrupole ion trap and Fourier-transform ion-cyclotron resonance, and sector mass spectrometry. Hybrid instruments intend to combine the strengths of the component analysers. 

Farre M, Perez S, Gajda-Schrantz K, Osorio V, Kantiani L, Ginebreda A, Barcelo D (2010) First determination of C60 and C70 fullerenes and N-methylfulleropyrrolidine C60 on the suspended material of wastewater effluents by liquid chromatography hybrid quadrupole linear ion trap tandem mass spectrometry. J Hydrol 383(l-2) 44-51... 

QqLIT-MS-MS Quadrupole linear ion trap tandem mass spectrometer... 

One of the best tools for metabolite profiling is the hybrid QTRAP MS/MS system (Applied Biosystems).119-121 While the hybrid QTRAP MS/MS was initially considered a premier tool for metabolite identification, it has more recently been seen as a tool for quantitation and metabolite profiling. Li et al.122 described the use of a hybrid QTRAP MS/MS system for discovery PK assays plus metabolite profiling in the same analytical procedure. Because QTRAP MS/MS may be used as a triple quadrupole MS system, it can be used as part of a quantitative HPLC/MS/MS system. Because QTRAP MS/MS also has linear ion trap capabilities, it can be used for metabolite screening and characterization—essentially it combines the capabilities of a triple quadrupole mass spectrometer and a linear ion trap mass spectrometer. 

Principle. The cylindrical quadrupole ion trap is based on the same principle as the quadrupole mass filter, but the geometry is different (Fig. 2.16). The cylindrical QIT, or Paul trap, was developed almost simultaneously with the quadrupole mass filter [232, 233]. Recently, a variant of the theme has emerged, the linear quadrupole ion trap [236], which is a device built like a quadrupole mass filter with extra trapping end electrodes for the axial direction. Under stable conditions, ions moving around inside such traps will ideally continue to do that forever. 

In the triple quadrupole linear ion trap, tandem MS is performed in space where the LIT serves only as a trapping and mass-analyzing device. Figure 1.25 illustrates the difference between quadrupole CID spectra and trap CID spectra for trocade. 

Another recent innovation is the QTrap mass spectrometer. The QTrap MS system combines the capabilities of a triple quadrupole mass spectrometer and a linear ion trap mass spectrometer into one MS system. Initially, the QTrap MS was used primarily as a tool for metabolite identification studies [34, 35, 38]. As reported by Li et al. [138], the QTrap MS can also be used as an excellent system for the quantitative analysis of discovery PK samples. The advantage of the QTrap MS system for quantitative analysis is that it can be used to look for plasma metabolites of the NCE and provide an easy way to monitor them while providing the quantitative data on the NCE. 

Since the analytical point of view most of current analytical methods are based on LC-MS/MS, but for some classes of pesticides GC-MS continues being the technique of choice. The use of quadrupole ion trap (QIT) to analyze multiple pesticide residues is limited to several multiclass pesticides in fruit [162], because of the limited number of ions that can be isolated at the same time. For this reason, the use of several time windows is required and this is indeed a strong limitation in practice. The use of hybrid triple quadrupole linear ion trap (QqLlT) mass spectrometer has provided significant contribution to the development of high-sensitive multiresidue analytical methods for pesticide control. An example of application is the method reported by Hernando et al. for the analysis of pesticide residues in olive oil [65]. 

Essentially, the ion storage trap is a spherical configuration of the linear quadrupole mass filter. The operations, however, differ in that the linear filter passes the sorted ions directly through to the detector, whereas the ion trap retains the unsorted ions temporarily within the trap. They are then released to the detector sequentially by scanning the electric field. These instruments are compact (benchtop), relatively inexpensive, convenient to use, and very sensitive. They also provide an inexpensive method to carry out GC/MS/MS experiments (Section 2.2.7) (GC is gas chromatography). 

LIT The linear ion trap (LIT) (also referred to as a two-dimensional, or 2D, trap) is a variation on the transmission quadrupole mass analyzer. In the LIT, the quadmpole is constructed such that either ions can be analyzed immediately or, ions can be trapped and held in the quadrupole region and then analyzed (Hager, 2002 Schwartz et al., 2002). Various types of MS/MS can be performed, as described in Chapter 3. 

The two-dimensional (2-D) or linear ion trap (LIT) emerged in the 2000s as an effective alternative to the 3-D trap. Before 1995, linear traps were used primarily as ion storage/transfer/ion-molecule reaction devices in combination with FTICR (Senko et al., 1997 Belov et al., 2001), TOF (Collings et al., 2001), 3D ion trap (Cha et al., 2000), and triple-quadrupole (Dolnikowski et al., 1988) mass spectrometers because LITs offer better ion storage efficiencies in comparison to 3D quadrupole ion traps of the same dimensions (Hager, 2002 Schwartz et al., 2002). In 2002, commercial LITs were introduced as either stand-alone mass spectrometers (Schwartz et al., 2002) or as part of a triple quadrupole mass spectrometer (Hager, 2002). 

The LIT introduced as part of a triple-quadrupole mass spectrometer is marketed under the name QTRAP. As shown in Fig. 1.26, the ion path and the differentially pumped region of QTRAP are similar to a triple quadrupole (API 3000, API 4000, and API 5000), except the Q3 is capable of functioning as a linear trap. QTRAP and its capabilities are described in detail in Chapter 3. Table 1.2 compares some of the advantages and limitations of QTRAP and LTQ mass spectrometers. 

Macek, B., Waanders, L. F., Olsen, J. V., and Mann, M. (2006). Top-down protein sequencing and MS3 on a hybrid linear quadrupole ion trap-orbitrap mass spectrometer. Mol. Cell. Proteomics 5 949-958. 

For abbreviation of analyte names see Sect. Abbreviations . ACN acetonitrile, APCI atmospheric pressure chemical ionization, dial, microdialysis samples, ESI electrospray ionization, FA formic acid, iso isocratic, IT ion trap, lin range linear range, MeOH methanol, MRM multiple reaction monitoring, MS full scan mass spectrometry, n.s. not specified, OAc acetate, QqQ triple quadrupole mass spectrometer, SIM selected ion monitoring, Solv HPLC solvent, SQ single quadrupole mass spectrometer, T temperature Ratios given as v/v... 

The quadrupole ion trap is a three dimensional analogue of the linear quadrupole mass analyzer [71,72]. It consists of a cylindrical ring electrode and two end-cap electrodes. Both end-cap electrodes contain a whole for injecting and ejecting ions into and out of the ion trap (Fig. 8.11). A relatively high pressure of helium damping gas (about 0.1-0.4 Pa) is present in the ion trap in order to kinetically cool the trapped... 

The linear trap with axial ejection was invented by Hager, from MDS Sciex, in 2002 [20], Figure 2.31 displays a scheme of such an ion trap included in the ion path of a triple quadrupole mass spectrometer. 

View of the linear trap included in a triple quadrupole at q2. This instrument can be operated as a regular triple quadrupole or with a trap. Reproduced from Hager J.W., Rapid Comm. Mass Spectrom., 16, 512-526, 2002, with permission. 

Linear trap with slots cut in two opposite rods. Sizes are 12 mm for sections A and C and 37 mm for B. Detectors D are placed off-line and ions are attracted by the conversion dynodes. The slots are 30 x 0.25 mm. Drawn according to the data from Schwartz J.C., Senko M.W. and Syka J.E.P., A Two-Dimensional Quadrupole Ion Trap Mass Spectrometer , Proceedings of the 50th ASMS Conference on Mass Spectrometry and Allied Topics, Orlando, Florida, 2002. 

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