Multiple reaction monitoring triple quadrupole mass analyzers

Various analyzers have been used to analyze phenolic compounds. The choice of the MS analyzer is influenced by the main objective of the study. The triple quadrupole (QqQ) has been used to quantify, applying multiple reaction monitoring experiments, whereas the ion trap has been used for both identification and structure elucidation of phenolic compounds. Moreover, time-of-flight (TOF) and Fourier-transform ion cyclotron resonance (FT-ICR) are mainly recommended for studies focused on obtaining accurate mass measurements with errors below 5 ppm and sub-ppm errors, respectively (Werner and others 2008). Nowadays, hybrid equipment also exists, including different ionization sources with different analyzers, for instance electrospray or atmospheric pressure chemical ionization with triple quadrupole and time-of-flight (Waridel and others 2001). 

ToF analyzers as well as hybrid instruments that combine two or more mass-resolving components, such as quadrupole-ToF (Q-ToF), ion-mobility ToF, and ion-trap-ToF, as well as the high-resolving Fourier transform (FT) analyzer Orbitrap and ion cyclotron resonance (ICR). For targeted analysis, a multiple-reaction monitoring instrument based on triple-quadrupole technologies (QQQ) has provided unrivaled sensitivity for MSI of pharmaceuticals, yet its targeted nature renders it unsuitable for discovery-based research. 

Triple quadrupole instruments (Section 6.4.3) have not previously been considered suitable for use with MALDl sources in view of their nature as scanning analyzers (serial recording of a mass spectrum resulting in very low duty cycle in full spectral acquisitions) with a limited miz range. However, for the present purpose of small molecule quantitation by MALDl, neither of these limitations applies. In particular, if the so-called multiple reaction monitoring (MRM) mode of tandem mass spectrometry is... 

Figure 13.7 Setup for mass specirrmietry-based quantitative real-time analysis. The outlet flow of a cwtinuous stirred enzyme membrane reactor (EMR) is continuously analyzed by multiple reaction monitoring in an electrospray ionization triple quadrupole mass spectrometer after flow reduction (SI), dilution (T) and another flow reduction (S2) (S6j. Reprinted by permission from Macmillan Publishers Ltd Nature Chemical Biology [Bujara, M., SchumperU, M., Pellaux, R., Heinemann, M., Panke, S. (2011) Optimization of a Blueprint f

First, if a multiple mass analyzer instrument is used, the pseudomolecular ion can be colHded with a stream of gas to generate collisionally induced dissociation (CID) and the formation of structurally significant fragment ions. MS/MS with selected reaction monitoring in a triple quadrupole is the method of choice for quantitation. Structure determination or confirmation is done by means of any of the available MS/MS fragmentation techniques triple quadrupole, ion trap, quadrupole-TOF, or FT-ICR. 

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