Linear-trap quadrupole Orbitrap mass spectrometer

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. 

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. 

Some mass spectrometers combine several types of analysers. The most common ones include two or more of the following analysers electromagnetic with configurations EB or BE, quadrupoles (Q), ion traps (ITs) with Paul ion traps or linear ion traps (LITs), time-of-flight (TOF), ion cyclotron resonance (ICR) or orbitrap (OT). These are named hybrid instruments. The aim of a hybrid instrument is to combine the strengths of each analyser while avoiding the combination of their weaknesses. Thus, better performances are obtained with a hybrid instrument than with isolated analysers. Hybrids are symbolized by combinations of the abbreviations indicated in the order that the ions travel through the analysers. 

Recently introduced tandem mass spectrometers, having both features, such as quad-rupole linear ion trap (QqLIT, LTQ or Q-trap), quadrupole time-of-fiight (QqTOF), LTQ-Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS), and LTQ-Orbitrap, and so on, have allowed for the development of several new methods for acrylamide detection [107,108]. 

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