Triple quadrupole mass spectrometers limitations

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. 

Detection of imatinib is performed by triple quadrupole mass spectrometer with an electrospray ionization (ESI) interface operated in positive ion mode [103, 104, 106,107,109,110]. Except the methods published by Parise et al. for imatinib and its main metabolite [108], and for nilotinib [111], where a single quadrupole mass spectrometer was used, most TKIs are analyzed in plasma by atmospheric pressure ionization (electrospray or turbo ion spray) coupled to triple stage mass spectrometer. Expectedly, higher limit of quantifications for imatinib (30 ng/ml) [108], and nilotinib (5 ng/ml) [111], are obtained for the assays using single quadrupole MS (see Table 2). 

The identity of the defined peptides was confirmed by electrospray mass spectrometry [13,62] and the purity of defined peptides was higher than 80% as determined by HPLC. The amino acid composition of selected peptide libraries and of the sublibraries was determined by pool sequencing [14] (Fig. 11.1) and amino acid analysis. Deviations from equimolar representation of the amino acids in randomized sequence positions were found to be within the error limits of the analytical methods [12]. Electrospray mass spectrometry for pattern analysis of peptide libraries differing in the position of the defined amino acid was carried out with a triple quadrupole mass spectrometer (Fisons, Manchester, UK) (Fig. 11.2). 

Impressed by the information provided by Py-FIMS, another research group developed pyrolysis-molecular beam mass spectrometry (Py-MBMS) by coupling a quartz pyrolysis chamber to the inlet of a triple-quadrupole mass spectrometer. This group wished to study the organic matrix of forest soils and saw two limitations for the application of Py-FIMS to their study first, that the very small sample used in Py-FIMS might not be representative of the macro soil sample, and second, that the time required for each sample analysis by Py-FIMS was relatively long if one wished to examine and compare a large number of soil samples. 

The uptake of HRMS instrumentation into metabolite identification laboratories points to future developments and uses for these types of mass analyzers. From a hardware perspective, developments in TOF and Orbitrap technology will be needed to address lingering issues specific to these analyzers. In the TOF area, current commercial systems just coming to the market have addressed historical limitations of resolution, dynamic range, and mass accuracy. It remains to be seen if these specifications are sufficient or if further gains are needed. These instruments are not yet as sensitive as high-end triple quadrupole mass spectrometers, and improvements are needed in this area. For Orbitrap-based systems, the main limitations are scan speed and sensitivity. As... 

HPLC-MS has now become the analytical method of choice for the quantitation of stilbenoids in the grapevine and wine. Buiarelli et al. developed a method for the quantitation of several stilbenoid monomers E and Z forms of resveratrol, piceid, piceatannol, and astringin) in 19 red and 3 white Italian wines by HPLC-MS-MS using a triple quadrupole mass spectrometer without the need for sample preparation [53]. The detection limits were about 50 ng mL for all these monomers. 

Waters Acquity UPLC with micro-titer well-plate auto-sampler (Waters Corp., Milford, MA, USA) and Waters Premier XE triple quadrupole mass spectrometer (Waters Corp., MicroMass UK Limited). 

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