Quadrupole mass spectrometer linear

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. 

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. 

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. 

The MALDI triple-quadrupole mass spectrometer generates calibration curves with linearity and dynamic ranges similar to those typically expected from a triple-quadrupole mass spectrometer. In most cases, linearity is established over three orders of magnitude with suitable accuracy and precision. Figure 11.5 depicts calibration curves obtained for some common drugs using neat standards. 

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 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. 

Many similar applications of quadrupole linear ion trap instruments have been reported [320-322,329,330], As discussed above, the Q-Trap is a triple quadrupole mass spectrometer capable of performing QMF type and 2D ion trapping experiments. This mass spectrometer can be operated exclusively in the QMF mode, as with a conventional QMF, or it can be operated exclusively in the ion trapping mode similar to a conventional 2D ion trap mass spectrometer. Advantages of using a Q-Trap mass spectrometer over a conventional QMF mass spectrometer come into play when one is attempting to perform both quantitative and qualitative metabolite detection/identification experiments from a single injection rather than separate... 

Temperature programmed hydrogenation of toluene was studied with the AMI-100 equipped with a quadrupole mass spectrometer (Balzers MSC 200 Thermo-Cube). A gas mixture of hydrogen, argon and toluene was fed into the reactor (a U-tube) in which the catalyst sample was loaded, and the temperature of the sample was raised linearly from 373 to 473 K. The exiting gas stream was analysed by the mass spectrometer utilising Quadstar 421 software. The conversion was calculated from the toluene molar flows. 

The triple quadrupole mass spectrometer consists of a linear combination of three quadrupole mass analyzers. Figure 9.15 [2,56,111]. Only the first and third quadrupole have scan capability. The middle quadrupole, which is sometimes a multipole device of higher order, is a radio frequency-only, gas-filled collision cell with ion focusing properties. All ions above a certain threshold m/z value are transmitted by the middle quadrupole. An offset voltage between the ion source and collision cell can be adjusted to allow the collision energy to be varied between zero and about 200 eV. Inert gases (e.g. He, Ar, Xe) at a pressure of about 2-4 mTorr are commonly used as targets to... 

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