Q Trap

LITs capable of scanning, axial or radial excitation of ions, and precursor ion selection for MS/MS experiments [118,134-136] have lately been incorporated in commercial mass spectrometers (Fig. 4.39). The replacement of Q3 in a QqQ instrument with a scanning LIT, for example, enhances its sensitivity and offers new modes of operation (Applied Biosystems Q-Trap). Introduction of a scanning LIT [118,135] as MSI in front of an FT-ICR instrument (Thermo Electron LTQ-FT) shields the ultrahigh vacuum of the FT-ICR from collision gas and decomposition products in order to operate under optimum conditions. In addition, the LIT accumulates and eventually mass-selects ions for the next cycle while the ICR cell is still busy with the previous ion package. 

Hopfgartner, G. Zell, M. Q trap MS a new tool for metabolite identification, in Using Mass Spectrometry for Drug Metabolism Studies, ed. Korf-macher, W. A., CRC Press, 2004. 

In another investigation, the volatile compounds were isolated [19] using a Porapack Q trap by vacuum for 2 h and were then eluted with hexane. The esters were the chemical class of compounds that predominated in the samples among 21 volatile compounds detected. Ethyl butanoate, ethyl 2-methylbutano-ate, 1-butanol, ethyl hexanoate, 3-hydroxy-2-butanone, ethyl octanoate, acetic acid, linalool, palmitic acid, and oleic acid were identified in cupuacu pulp by solid-phase extracton [15]. 

Experimental. PRODAN was purchased from Molecular Probes and the purity checked by reverse phase HPLC. There were no detectable impurities. Stock solutions (1 mM) were prepared in absolute ethanol and stored in the freezer. CF3H was purchased from Matheson and passed through a single adsorptive Q trap (Matheson) prior to entering the pumping system. According to the manufacturer this gives an 02 level < 5 ppm. 

Linear Range The concentration range where increasing concentrations of an analyte have a proportional increase in LC-MS response. Overall QqQ-type mass spectrometers (triple quadmpoles, Q-TRAPS) are superior in terms of linearity. Most common causes for nonlinear response include MS detector saturation, dimmer/adduct formation, API droplet/vapor saturation at high concentrations, and space charge effects. 

Figure 15 The kinetic scheme illustrating the interplay between exciton (S) and charge carrier (q) trapping by crystal defects (S0t)-The PL spectrum of the crystal contains the excitonic emission (kr, hvm) and the trap center emission (kj., hi ). the latter being controlled by the number of the defect sites available for excitation. The exciton capture process (yst) competes directly with charge carrier trapping (yqt). The defects filled with charge reduce the emission resulting from radiative relaxation of the excited states produced at defect sites. For further explanations, see text.

Le Blanc, j. C., Hager, ).W., Ilisiu,A. M., Hunter, C Zhong, F., Chu, I. (2003). Unique scanning capabilities of a new hybrid linear ion trap mass spectrometer (Q TRAP) used for high sensitivity proteomics applications. Proteomics 3, 859-869. 

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... 

A third type of MS/MS instruments is a hybrid of tandem-in-space and tandem-in-time devices, including the Q-trap (QQ-2D-linear trap) [45] and the ion trap-FT-ICR (2D-linear ion trap-FT-ICR) [46]. The Q-trap takes the configuration of triple quadrupole, with the third quadrupole replaced by a 2D-linear ion trap. The uniqueness of this design is that the 2D-linear ion trap component can be used to perform either (a) a normal quadrupole scan function in the RF/DC mode or (b) a trap scan function by applying the RF potential to the quadrupole. It is well-suited for both qualitative and quantitative studies. In the case of ion Trap-FT-ICR, it combines ion accumulation and MS" features of a 2D-linear ion trap with excellent mass analysis capability (mass resolution, mass accuracy, and sensitivity) of FT-ICR. 

K. Sandra, B. Devreese, J. Van Beeumen, I. Stals, M. Claeyssens, The Q-trap MS, a novel tool in the study of protein glycosylation, J. Am. Soc. Mass Spectrom., 15... 

Wen B, Fitch WL (2009) Screening and characterization of reactive metabolites using glutathione ethyl ester in combination with Q-trap mass spectrometry. J Mass Spectrom 44 90-100... 

Ion Trap (IT) Similar to Q, traps have a Low cost instruments 100 4000 4,000... 

Commercial LITs were introduced in 2002 as either a stand-alone mass spectrometer (LTQ) [318] or as part of a triple quadrupole (Q-Trap) [319] or in 2005 as part of hybrid tandem mass spectrometers (LTQ-Orbitrap and LTQ-FTICR) [88,90], Application of LTQ-FTICR for metabolism studies has been reviewed by Shipkova et al. [90], In comparison to other mass analyzer types, FTICR-based mass spectrometers are not very popular for metabolite identification studies due to availability of less expensive and more user-friendly LTQ-Orbitrap and Q-TOF-based systems. Another limitation associated with the FTICR-based hybrid mass spectrometers is the TOF effect, which results in efficient trapping of only the high-mass ions [90],... 

King et al. [164] used Q-Trap to simultaneously quantify an NCE and collect information about circulating metabolites, dosing vehicle, interfering matrix components, and co-eluting metabolites. The ability to operate the LIT in the enhanced MS (EMS) mode with a scan speed of 4000 Th/s allowed the combined SRM transitions (parent/IS) and the full scans to be completed in 0.31 s. The quantification data... 

Xia et al. [328] demonstrated the utility of IDA approach to collect maximum amount of information with the minimum number of analytical runs during the course of identification of in vitro formed metabolites of gemfibrozil. The Q-Trap tandem mass spectrum contained fragment ions at mlz 113 and 85 and they were absent in the MS/MS spectrum generated using a 3D iontrap due to inherent low mass cutoff. With the 3D trap, fragment ions with mlz values lower than approximately one-third of the precursor ion were not detected. 

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... 

Hager, J.W. and Yves Le Blanc, J.C., Product ion scanning using a Q-q-Q linear ion trap (Q TRAP) mass spectrometer, Rapid Commun. Mass Spectrom., 17(10), 1056, 2003. 

FIGURE 6.4 Detection and characterization of the GSH adduct of acetaminophen using the API 4000 Q Trap instrument. A mixture of labeled and nonlabeled GSH was used to trap the reactive metabolite of acetaminophen (lOOmM) incubated with rat liver microsomes. (a) The ion chromatogram obtained from the NL experiment, (b) The precursor protonated molecular ions detected for the peak at 9.2min. (c) An MS/MS spectrum of the precursor ion at m/z 457. (From Mutlib, A. et al., Rapid Commun. Mass Spectrom., 19, 3482, 2005. With permission.)... 

Figure 7 IS-CID-MS analysis of O-PS (1.0 pg pr ) from Salmonella riogrande 0 40. The experiments were performed using a 4000 Q-Trap mass spectrometer (Applied Biosystems/Sciex, Concord, Ontario, Canada) via a CE-MS interface. A sheath solution (isopropanol-methanol, 2 1) was delivered at a flow rate of 1 plmin The orifice voltage was set at +400 V. Separations were obtained on approximately 90 cm length of bare fused-silica capillary using 15 mmol ammonium acetate...

Gradient reverse phase HPLC with mass spectrometric detection is used to confirm Caribbean or Pacific CTX-1 in the fish tissue extracts. Identification is based on mass and retention time equivalent to C-CTX-1 or P-CTX-1 reference materials. The concentration of reference standard used is 10 ng/mL. The LC/MS/MS system consists of an LC system (Agilent Technologies Model 1100, Palo Alto, CA) coupled to a 4000 Q Trap mass spectrometer (Applied Biosystems, Foster City, CA). LC separations are performed on a Luna C8 (2) column (2.0 x 150 mm, 5 pm, Phenomenex, Torrance, CA) at a column temperature 40°C. Mobile phase is water (A) and acetonitrile (B) in a binary system, with 0.1% formic acid as additive. The elution gradient is 35% B for 2 min, linear gradient to 80% B at 30 min, 95% B at 35 min, hold at 95% for 10 min, return gradient to 35% B at 50 min, and hold for 10 min before the next injection. 

Figure 11.11 Indinavir phase I in vitro metabolites identified with a Q-TRAP instrument matched with the Meteor (version 7) prediction.

Overall, the use of a Q-TRAP Instrument with IDA demonstrated powerful capabilities of high throughput quality data acquisition. APEX metabolite identification examines the isotope patterns of the targeted ions to give more accurate results, increasing the confidence level of the automation. Meteor showed satisfactory prediction abilities that could be improved with more knowledge about more complicated or combined biotransformation pathways. In fact, in Meteor (version 12, the current version), version, M3 is predicted, albeit via the reverse mechanism to the one proposed i.e. aromatic ring... 

---