Orbitrap tandem

With recent instrumental development, such as fast LC, fast GC and two-dimensional gas chromatography (GCxGC) and advanced tandem hybrid MS detection systems (i.e., QqTOF, QqLIT, Orbitrap) the analysis of complex mixtures... 

Recent innovations in mass spectrometry have provided incorporation of two, three, and four analyzers into commercially available tandem instruments. In addition, different mass analyzers may be combined to form a hybrid mass spectrometer such as the quadrupole-TOF (Q-TOF). Various types of tandem mass spectrometers include the quadruopole-TOF, time-of-flight-time-of-hight (TOF-TOF), triple-quadrupole, and Orbitrap-FTICR configurations. 

Besides this spatial separation method using successive analysers, tandem mass spectrometry can also be achieved through time separation with a few analysers such as ion traps, orbitrap and FTICR, programmed so that the different steps are successively carried out in the same instrument. This method was described in the case of the ion traps and FTMS in Chapter 2. The maximum practical number of steps for these instruments is seven to eight. In these instruments the proportion of ions transmitted is high, but at each step the mass of the fragments becomes lower and lower. 

From the time of the second edition published in 2001 until now, much progress has been achieved. Several techniques have been improved, others have almost disappeared. New atmospheric pressure desorption ionization sources have been discovered and made available commercially. One completely new instrument, the orbitrap, based on a new mass analyser, has been developed and is now also available commercially. Improved accuracy in low-mass determination, even at low resolution, improvements in sensitivity, better detection limits and more efficient tandem mass spectrometry even on high-molecular-mass compounds are some of the main achievements. We have done our best to include them is this new edition. 

Vallverdu-Queralt, A. Jauregui, O. Medina-Remon, A. Andres-Lacueva, C. Lamuela-Raventos, R.M. 2010. Improved characterization of tomato polyphenols using liquid chromatography/electrospray ionization linear ion trap quadrupole Orbitrap mass spectrometry and liquid chromatography/electrospray ionization tandem mass spectrometry. Rapid Comm. Mass Spectrom. 24 2986-2992. 

Trapping-type instrument capable of tandem-in-time experiments and can be linked to ToF analyzer (QIT-ToF). h Trapping-type instrument capable of tandem-in-time experiments and can be linked to Q, FTICFt, or Orbitrap analyzers (e.g., QqLrT-FTICFt, and LIT-Orbitrap). 

Mass spectrometers are composed of three main components the ionization source, the mass analyzer, and the detector. With the development of different mass analyzers, the choice of mass spectrometer for a specific analysis becomes critical (53), for example, if the analysis is to quantitatively profile all proteins in a sample or quantify a preselected set of protein targets. One or a combination of mass analyzers, such as time of flight (TOF), quadrupole (Q), ion trap (IT), ion cyclotron resonance, and Orbitrap , can be implemented in MS or tandem MS (MS/MS). 

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],... 

Various hybrid tandem mass spectrometers, which combine two or more distinct types of mass analyzers, have been developed to maximize analytical performance and functionality. From the standpoint of ion/ion reactions, the incorporation of an electrodynamic ion trap into a hybrid instrument allows for the physical separation of the three basic steps involved in an ion/ion reaction experiment, that is, ionization, ion/ion reaction, and mass analysis of reaction products. The separation of these processes provides for the highest degree of flexibility and minimal compromises in the optimization of each step. To date, three major types of hybrid instrnments have been described for ion/ion reaction studies using an electrodynamic ion trap as the reaction vessel. The three major types of hybrid instruments are (i) quadrupole/TOF tandem mass spectrometer (ii) Orbitrap and (iii) LIT /FT-ICR. 

The fundamental process of MS/MS (in a tandem mass spectrometer) is that a particular precursor ion is fragmented (decomposed) into a smaller product ion accompanied by the loss of a neutral fragment. The precursor ion is usually selected in the first analyzer, reacted by some means in a specialized chamber (see below) to produce product ions that are then separated in a second analyzer, hence the terms mass spectrometry/mass spectrometry and tandem mass spectrometry. As discussed later, precmsor and product ion analyses can be separated in space, using sequential analyzers that are either of the same type or in hybrid configurations, or separated in time in the latter the two analytical processes are carried out sequentially, within the same analyzer. There are several MS/MS instrument combinations, including QqQ, QIT, LIT, TOF/TOF, QTOF, LlT-orbitrap, and LIT-FT-ICRMS. 

In tandem-in-space MS/MS a collision cell is placed between two analyzers that may be the same, e.g., QqQ or TOF/TOF, or a combination of different types, e.g QTOF or LT-orbitrap. The analyzers are separated in space in all such instruments. 

Linear Ion Trap-Orbitrap Mass Spectrometer A recent addition to the family of hybrid tandem mass spectrometers is a linear ion trap (LTQ)-orbitrap mass spectrometer [69,70]. Conceptually, this instrument is similar to the LTQ/FT-ICR tandem mass spectrometer discussed above but uses an orbitrap in place of a Penning trap, thus avoiding the complexity and cost of a superconducting magnet. The working principle of an orbitrap was described in Section 3.9 [71,72]. A schematic diagram of the LTQ/orbitrap mass spectrometer is shown in Figure 4.14. This hybrid tandem mass spectrometer consists of an... 

Figure 4.14. Schematic diagram of the LTQ/orbitrap hybrid tandem mass spectrometer a, transfer octopole b, C-trap c, front gate electrode d, rear trap electrode e, ion optics f, inner orbitrap electrode g, outer orbitrap electrode. (Reproduced from ref. 69 by permission of the American Chemical Society, Washington, DC, copyright 2006.)...

A variety of mass analyzers have been used in MSI experiments such as TOP, quadrupole ion trap (QIT), linear ion trap (LIT), QqQ, Fourier transform ion cyclotron resonance (FTICR), and Orbitrap. Also, various tandem configurations of these mass analyzers such as QqTOF, QqLIT, and TOF/TOF have been used. Due to the many possible interferenees from endogenous compounds or from the matrix, the use of tandem mass speetrometry (MS/MS or MS") or the ability to perform high-resolution and aeeurate mass measurements for the analysis of drugs by MALDI is essential. An overview of some of the established instrumentation and their respeetive eapabilities is presented below. 

Tandem mass spectrometry (MS/MS) is very useful for the amino acid sequencing of peptides, and has been used widely in both protein biochemistry and pro-teomics to identify proteins, to deduce the sequence of a peptide, and to detect and locate post-translational modifications. Until around a decade ago, the concept of amino acid sequencing by MS-technologjes was synonymous with ESI-MS/MS, but today MALDI-MS/MS techniques are implemented in high-performance instruments such that the quality of MALDI tandem mass spectra is comparable with that of ESI-MS/MS spectra. Currently, MALDI tandem mass spectrometers exist in a number of geometries, including TOF-TOF, Q-TOF, ion trap and orbitrap analyzers that each provide unique analytical features for the sequencing of peptides and proteins by MS/MS (details of the instrumentation for different types of MS/MS are provided in Chapter 2). 

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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