Quadrupole ion trap analyzer

It is certainly desirable to have at least sufficient resolution to resolve isotopic patterns to their nominal mass contributions. However, not every mass analyzer is capable of doing so with any ion it can pass through. Such conditions often occur when ions of several thousand u are being analyzed by quadrupole, time-of-flight or quadrupole ion trap analyzers, and hence it is useful to know about the changes in spectral appearance and their effect on peak width and detected mass. [42]... 

Please note that analytes introduced to GC columns need to be volatile and amenable to detection using the detector at the column outlet. To render less volatile compounds amenable to analysis by GC-MS, derivatization is often conducted by reacting sample components with a generic or specific reagent. While derivatization is normally conducted off-line, in principle, it can be done on-line. In one smdy, a system was developed in which analytes were first separated in an LC column followed by on-line derivatization, and introduction of the resulting mixture to a GC column for further separation and detection by MS using an electron ion source and a quadrupole ion trap analyzer [11]. 

A quadrupole ion trap analyzer produces a three-dimensionally rotationally symmetrical quadrupole field capable of storing ions at selected mass-to-charge ratios [28,29]. The system is relatively inexpensive, simple in design with moderate scan rates (>0.2 s/scan). However, it is limited to a low mass range ( 2000 Da) and only has unit mass resolution. 

Photoionizalion Muss analyzer Magnetic sector Quadrupolc analyzer Quadrupole ion trap analyzer Timc-of-flighl MS Fourier transform MS Electrical detection Data statitms... 

Almost any type of analyzer could be used to separate isotopes, so their ratios of abundances can be measured. In practice, the type of analyzer employed will depend on the resolution needed to differentiate among a range of isotopes. When the isotopes are locked into multielement ions, it becomes difficult to separate all of the possible isotopes. For example, an ion of composition CgHijOj will actually consist of many compositions if all of the isotopes ( C, C, H, H, 0, O, and 0) are considered. To resolve all of these isotopic compositions before measurement of their abundances is difficult. For low-molecular-mass ions (HjO, COj) or for atomic ions (Ca, Cl), the problems are not so severe. Therefore, most accurate isotope ratio measurements are made on low-molecular-mass species, and resolution of these even with simple analyzers is not difficult. The most widely used analyzers are based on magnets, quadrupoles, ion traps, and time-of-flight instruments. 

Ion trap analyzer. A mass-resonance analyzer that produces a three-dimensional rotationally symmetric quadrupole field capable of storing ions at selected mass-to-charge (m/z) ratios. 

Different mass analysers can be combined with the electrospray ionization source to effect analysis. These include magnetic sector analysers, quadrupole filter (Q), quadrupole ion trap (QIT), time of flight (TOF), and more recently the Fourrier transform ion cyclotron resonance (FTICR) mass analysers. Tandem mass spectrometry can also be effected by combining one or more mass analysers in tandem, as in a triple quadrupole or a QTOF. The first analyzer is usually used as a mass filter to select parent ions that can be fragmented and analyzed by subsequent analysers. 

For the characterization of compounds extracted from plants, wool and dye baths, acquisition in the NI mode is used. The main signals in the mass spectra of each colourant are attributed to deprotonated molecular ions [M H]. More detailed studies can be performed by ESI MS" with a quadrupole ion trap mass analyzer, and such a set-up was used e.g. for the investigation of photo-oxidation processes of components of weld and onion skins.[29]... 

Mass analyzers interrogate and resolve ions produced by an ion source based on their m/z ratios. Several types of mass analyzers are utilized for proteomic analysis including time-of-flight (TOF) quadrupoles, ion traps, and Fourier transform ion cyclotron resonance (FTICR). Mass analyzers may be assembled in hybrid configurations. MS instruments such as quadrupole TOF and quadra-pole ion trap-FTICR facilitate diversified applications and achieved great success. 

Figure 2.17. Schematic of a linear quadrupole ion trap (QIT). This type of analyzer consists in principle of a quadrupole analyzer with electrodes at the ends to block ion passage in the z-direction.

Three-dimensional quadrupole ion trap Quadrupole (RF) ion traps are the newest of the commercially available mass analyzers, despite having been invented at about the same time as the quadrupole mass filter, nearly 50 years ago. The Paul ion trap... 

Perhaps the simplest mass analyzer of all, the TOF mass spectrometer [46] has experienced a reemergence in the past several years. Like the 3D quadrupole ion trap, the TOF analyzer has come to commercial prominence several decades after its initial introduction. The limitations of electronic components in the 1960s constrained the capabilities of the instrument, limiting its mass range and resolving power. The TOF analyzer operates in a pulsed mode, requiring either a pulsed ion... 

With the advent of linear quadrupole analyzers the full width at half maximum (FWHM) definition of resolution became widespread especially among instruments manufacturers. It is also commonly used for time-of-flight and quadrupole ion trap mass analyzers. With Gaussian peak shapes, the ratio of / fwhm to Rio% is 1.8. The practical consequences of resolution for a pair of peaks at different m/z are illustrated below (Fig. 3.17). 

Note With the exception of the quadrupole ion trap, which uses buffer gas to damp ion trajectories, a reduced background pressure, i.e., better vacuum, is also beneficial for all other types of mass analyzers. 

The operation of magnetic sector (Chap. 4.3), linear quadrupole (Chap. 4.4), or quadrupole ion trap (Chap. 4.5) mass spectrometers in the repetitive scanning mode is useful for the identification of the components of a mixture. If quantitation is a major issue (below), selected ion monitoring (SIM) is preferably employed the term multiple ion detection (MID) and some others are also in use. [33] In the SIM mode, the mass analyzer is operated in a way that it alternately acquires only the ionic masses of interest, i.e. it jumps from one m/z value to the next. [34-39] The information obtained from a SIM trace is equivalent to that from a RIC, but no mass spectra are recorded. Thus, the scan time spent on a diagnostically useless m/z range is almost reduced to zero, whereas the detector time for the ions of interest is increased by a factor of 10-100. [40] An analogous improvement in sensitivity (Chap. 5.2.3) is also observed. 

The TOF mass analyzer has a low duty cycle, and the combination with an ion accumulation device such as an ion trap is therefore very advantageous. It offers also MS capabilities with accurate mass measurement. In all acquisition modes, the ions are accelerated into the time of flight for mass analysis. Various other hybrid mass spectrometers with TOF have been described, including quadrupole ion trap [70] and linear ion trap [58]. High energy tandem mass spectrometry can be performed on TOF-TOF mass spectrometers [71, 72]. 

Since the analytical point of view most of current analytical methods are based on LC-MS/MS, but for some classes of pesticides GC-MS continues being the technique of choice. The use of quadrupole ion trap (QIT) to analyze multiple pesticide residues is limited to several multiclass pesticides in fruit [162], because of the limited number of ions that can be isolated at the same time. For this reason, the use of several time windows is required and this is indeed a strong limitation in practice. The use of hybrid triple quadrupole linear ion trap (QqLlT) mass spectrometer has provided significant contribution to the development of high-sensitive multiresidue analytical methods for pesticide control. An example of application is the method reported by Hernando et al. for the analysis of pesticide residues in olive oil [65]. 

The quadrupole ion trap, time-of-flight (QitTofMS) analyzer was first developed by Lubman [12,13] and co-workers. QitTofMS components were first sold commercially by R. M Jordan Company and a full commercial instrument first... 

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