Hybrid instrument

Hybrid time-of-flight mass spectrometers make use of a TOP analyser placed orthogonal to a beam of ions. Ions are deflected at right angles into the TOP analyser by a pulsed electrical potential from an electrode placed alongside the beam. 

By having a quadrupole analyser as a gate in conjunction with an orthogonal TOP analyser, a full mass spectrum of aU ions from an ion source may be obtained if the gate is open. Alternatively, precursor ions can be selected for MS/MS so as to give a fragment ion spectrum characteristic of the precursor ions chosen, which gives stractural information [39]. 

This family of instruments should nevertheless be developed, especially for fast routine analyses. 

In analogy with the techniques of coupling GC and LC to a mass spectrometer for the identification of the components of a mixture, McLafferty and co-workers [106a,173] designated as MS/MS the method of detecting fragmentations outside the source, as discussed previously. 

the mixture M,- analyzed is first ionized to obtain a set of molecular ions 

The energy spectrum recorded is thus used as a fingerprint to identify the molecular ion studied. In the case of GC (or LC)/MS, the traditional spectrum is used to determine the structure of the ion studied. 

Concerning the linked scan detection technique, the methodology remains the same, since in this case an ion may also be studied independently of other ions in the source (the decompositions measured are those produced in the first FFR). 

As anticipated in the sections on linear ion traps (Chap. 4.4.6), modem Fourier transform-ion cyclotron resonance (Chap. 4.7.11), and LIT-orbitrap mass spectrometers (Chap. 4.8.4), our instrumeaitation may efficiently be constructed by combining different types of mass analyzers and ion-gitiding devices in a single so-called hybrid instrument [219,220]. The driving force to do so is the desire to obtain mass spectrometers that unite the advantageous properties of each mass 

Geometries composing of an oaTOF as MS2 bear the advantage that advanced TOFs offer accurate mass measurements close the the accuracy of magnetic sector instruments. Currently, QqTOF systems can be regarded as the commercially most successful hybrid. While the linear quadrupole serves as MSI in MS/MS experiments, it is operated in RF-only mode when tandem MS is not intended, because 

The next higher level of performance can be achieved by replacing the oaTOF MS2 with an FT-ICR analyzer while employing a linear ion trap (Thermo Electron LTQ-FT) or a quadmpole as MSI (Bruker Daltonik APEX-Q). 

Note Besides accommodating to their versatility, there is nothing new to understand with hybrid instruments. Though exotic at a first glance, hybrids are governing today s market of mass spectrometers. 

Note Ion counting detectors also give signals upon impact of energetic neutrals, electrons, or photons. Therefore, care has to be taken, not to allow other particles than the mass-analyzed ions to hit the detector. 

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. 

Initially, most combinations of electromagnetic sectors with quadrupoles have been proposed. The first hybrids described were instruments of type BEqQ but several other 

Common combinations of electric (E) and magnetic (B) sectors, quadrupoles (Q) and collision cells (C). The lowercase q indicates a focusing quadrupole. 

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This chapter provides brief descriptions of analyzer layouts for three hybrid instruments. More extensive treatments of sector/TOF (AutoSpec-TOF), liquid chromatography/TOF (LCT or LC/TOF with Z-spray), and quadrupole/TOF (Q/TOF), are provided in Chapters 23, 22, and 21, respectively. 

Operation of the Combined Magnetic and TOF Sectors as a Hybrid Instrument... 

For some kinds of analyses, it is convenient to have two combined mass spectrometers. This combination naturally increases costs therefore purchase of such hybrid instruments tends to require much... 

Scanning techniques are carried out differently with such hybrid instruments as the triple quadrupole analyzer, the Q/TOF (quadrupole and time-of-flight), and double magnetic-sector instruments. 

In mass spectrometers, ions are analysed according to the ml7. (mass-to-charge) value and not to the mass. While there are many possible combinations of technologies associated with a mass-spectrometry experiment, relatively few forms of mass analysis predominate. They include linear multipoles, such as the quadrupole mass filter, time-of-flight mass spectrometry, ion trapping forms of mass spectrometry, including the quadrupole ion trap and Fourier-transform ion-cyclotron resonance, and sector mass spectrometry. Hybrid instruments intend to combine the strengths of the component analysers. 

Various tandem MS instrument configurations have been developed, e.g. sector instruments, such as CBCE, CBCECB or CECBCE, and hybrid instruments, e.g. BCECQQ (B = magnetic sector analyser, E = electrostatic analyser, C = collision cell, Q = quadrupole mass spectrometer), all with specific performance. Sector mass spectrometers have been reviewed [168],... 

TOF analyzers are especially compatible with MALDI ion sources and hence are frequently coupled in aMALDI-TOF configuration. Nevertheless, many commercial mass spectrometers combine ESI with TOF with great success. For proteomics applications, the quadrupole TOF (QqTOF) hybrid instruments with their superior mass accuracy, mass range, and mass resolution are of much greater utility than simple TOF instruments.21,22 Moreover, TOF instruments feature high sensitivity because they can generate full scan data without the necessity for scanning that causes ion loss and decreased sensitivity. Linear mode TOF instruments cannot perform tandem mass spectrometry. This problem is addressed by hybrid instruments that incorporate analyzers with mass selective capability (e.g., QqTOF) in front of a TOF instrument. 

Fig. 11.27. (a) NanoESI-CID-MS/MS spectrum of the [M-H] ion, m/z 2246.9, of a modified nonasaccharide obtained in a Q-TOF hybrid instrument and (b) proposed structure with fragments indicated. Reproduced from Ref. [137] by permission. Elservier Science, 2001. 

Note SRM is preferably performed on triple quadrupole, quadrupole ion trap, and Q-TOF hybrid instruments due to their ease of setting up the experiment and to their speed of switching between channels if monitoring of multiple reactions plays a role. 

Place the covered slides on a PCR thermal cycler with slide blocks or a hybridization instrument. 

Figure 1.3.A shows the scheme for another analytical information hierarchy that is complementary to the previous ones. Thus, gravimetries, titrimetries, classical qualitative analyses and sensors provide onedimensional information of the form F = where x is the signal concerned. On the other hand, instrumental techniques provide two-dimensional information that can be of two types depending on whether the signal (x) is combined with an instrumental parameter (y), time (f) or space (s). Some modem analytical techniques (several of which use hybrid instruments) furnish three-dimensional information by combining signals with one or two instrumental parameters (y, z), time and space. The great...

In the last decade, LC-MS system manufacturers have commercialized hybrid instruments that can operate in the ESI or the APCI mode with just a few simple modifications. Such instrumentation, based on Bajic s first prototype [49], is able to protonate compounds in the ESI mode together with those yielding characteristic APCI signature. Castoro [50] and Fischer et al. [51] first provided the utility of the dual atmospheric pressure ionization source. 

Fig. 8.1.1 Simple illustrations of a various mass spectrometers, a The triple-quadrupole tandem mass spectrometer (top panel). The middle set of quadrupoles are part of the collision cell (CC) and do not perform mass separation. MSI and MS2 indicate the first and second quadrupole mass separation devices, respectively. The bold arrow shows the path of ions, b Ion-trap mass spectrometer (middle left). The charged sections of the ion trap are not elliptical as drawn, but rather hyperbolic. The diagram is also two-dimensional, whereas the ion trap is three-dimensional. The ion path is such that ions enter the device and are trapped until a specific voltage ejects these ions, c Time of Flight mass spectrometer with a Reflectron (middle left). Ions are separated by the time it takes to pass through the instrument. The Reflectron improves/focuses the ions, d Hybrid Tandem mass spectrometer (bottom). The diagram shows that a quadrupole instrument can be combined with a different type of mass spectrometer, forming a tandem hybrid instrument...

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