Trapping-type analyzers

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. " ... 

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). 

Trapping-type instrument capable of tandem-in-time experiments and can be configured to analyze fragments generated externally (e.g., QqFTICR or LIT-FTICR). 

For the neutral loss scan, the first mass analyzer (Qj) scans all the masses (Figure 7(d)). The second mass analyzer (Q3) also scans, but at a fixed offset from the first mass analyzer. This offset corresponds to a neutral loss that is commonly observed for a particular class of compounds for example, the loss of 44 u (C02) from [M — H] ions will be indicative of carboxylic acids. Alkyl loss (C H2b+i) will be seen in the loss of 15, 29, or 43, etc. and the loss of 18 u (H20) will be indicative of a primary alcohol. A comprehensive table of common neutral fragments may be found in McLafferty and Turecek.32 The mass spectrum is then a record of all precursor ions that lose the specified neutral fragment. Again, neutral loss scans cannot be performed with trap-type MS instruments or with ToF analyzers. However, postacquisition analysis software can be used to search for the specified neutral loss. 

XRF analyses have been performed with a Philips PW 1400 spectrometer to get an indication of the amount of copper present in different trap types. Five traps were analyzed. 

Tbe reader new to mass spectrometry is advised to consult an appropriate introductory text [2-9]. A few mass spectrometric terms will be explained here by way of background and to outline the principles of choosing a flame ionization detector, ions are produced in the mass spectrometric detector, but the mass spectrometer is able to analyze these ions further according to their molecular weights or rather, mass-to-charge ratios (m/z, see below) to provide a mass spectrum. Different principles are employed to achieve this in a variety of types of mass spectrometer. The instruments most commonly used in GC—MS are known as magnetic sector, quadrupole and ion trap mass spectrometers. Their differences are not further described here. Bench-top systems are of the quadrupole or ion trap type. 

Fourier-transform (FT) mass analyzers belong to a special class of mass analyzer that detects ions non-destructively and periodically. Therefore, FT mass analyzers are trapping-type instruments. Because periodic and long detection times facilitate accurate ion recognition, FT mass analyzers offer the highest mass resolving power and accuracy of all instruments [23]. The concept of FT-MS was first described by Comisarow and Marshall in the 1970s [24]. The most important types of FT instruments available in the market include ion cyclotron resonance (ICR) [23] and orbital ion trap (orbitrap) [25] mass analyzers. 

Because the ion trap contains ions of all values of m/z at the same time (as well as neutral molecules that were not ionized prior to entering the trap), ion trap mass analyzers are also sensitive to overload and ion-molecule collisions that complicate the resulting spectrum. Recall that not all of the sample molecules get ionized—many remain uncharged. These neutral species move in a random path in the ion trap, resulting in collisions with ions as the ions oscillate in their stable trajectories. These collisions result in chemical ionization-type ionization events (Equation 3.20). This is sometimes referred to as self-CI. 

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. 

Instruments are available that can perform MS/MS type experiments using a single analyzer. These instruments trap and manipulate ions in a trapping cell, which also serves as the mass analyzer. The ion trap and fourier transform ion cyclotron resonance (FT-ICR) mass spectrometers are examples. 

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