Mass analyzer ion trap

Different types of mass analyzers have been used for anthocyanin analysis single or triple quadrupole mass analyzers, TOP mass analyzer,ion trap mass analyzers,and the combination of analyzers cited above. " ... 

Figure 2.11 Three dimensional (a) and linear (b) ion trap mass analyzers. Arrows indicate the entrance of ions from the source. Detectors are depicted as plates...

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]... 

QqLIT Triple quadrupole-linear ion trap mass analyzer... 

Figure 3.10 HPLC/MS/MS tandem mass spectrum of 3-Glc-28-Glc medicagenic acid obtained using an ion-trap mass analyzer. The spectrum illustrates the successive loss of two hexoses, the deprotonated aglycone, and a characteristic ftagment ion associated with medicagenic acid saponins.

The ion trap mass analyzer is similar to the quadrupole but with the important distinction that it can isolate and trap ions in an electrical field. Notably, the ion trap differs significantly from quadrupoles in design and operation in that triple quadrupoles perform tandem mass analysis on ions as they pass through an analyzer ion traps are capable of isolating and retaining specific ions for fragmentation upon collision with an inert gas in the same cell. An ion trap is about the size of a tennis ball and consists of a donut-shaped electrode and two perforated disk-like end-cap electrodes. 

What is one of the significant advantages of a linear (2D) ion trap mass analyzer when compared to a 3D (Paul) ion trap (increased ion capacity, which leads to improved sensitivity). 

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). 

Figure 2 Ion trap mass analyzer (Reproduced from http //www.wpi.biz/initiatives/2002/ 20020903.asp. With permission fromVarian, Inc.).

Various mass spectrometer configurations have been used for the detection of explosives, such as ion traps, quadrupoles and time-of flight mass analyzers and combinations as MS/MS systems. The ionization method is usually APCI with corona discharge [24, 25]. An example is given in Figure 20, which shows the schematic diagram of an explosive mass spectrometer detector [25]. It is based on an ion trap mass analyzer, an APCI source with corona discharge and a counter-flow introduction (CFI) system. The direction of the sample gas flow introduced into the ion source is opposite to that of the ion flow produced by the ion source. 

An ion trap mass analyzer has a variety of differing physical arrangements of its electrodes, but the primary objective remains the same to allow the ions to enter and then to trap them in space between the electrodes. Unlike the fly-through mass analysis scheme of a quadrupole, the ion trap mass analyzer stores the ions. They are then ejected to the detector as a function of the mass-to-charge ratio, typically by scanning the rf voltage. 

Fig. 8.11. Schematic illustration of a quadrupole ion trap mass analyzer with electrospray ion source.

The ion trap mass analyzer [2] (Fig. 2) consists of two end-cap electrodes, held at ground potential, and an interposed ring electrode, to which DC and RF voltages are applied. The ring electrode is a single surface formed by a hyperboloid of rotation. The end-caps are complementary hyperboloids having the same conical asymptotes z is an axis of... 

The majority of LC/MS systems use either quadruple or ion-trap mass analyzers. Because of the general paucity of fragment ions under routine operating conditions, instruments with true MS/MS capability, which allow CID of selected ions, have a clear advantage for identification and in providing low limits of detection. 

The operating principle of a quadrupole ion trap mass analyzer is similar to that of a standard quadmople but the geometry is different. A trap consists of three hyperbolic electrodes comprising a ring and two endcap electrodes. Applying voltages to these electrodes, results... 

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