Electromagnetic Fields Linear Ion-Trap Quadrupole LTQ Analyzers

Interaction with electromagnetic fields linear ion-trap quadrupole (LTQ) analyzers 

As discussed earlier, in the conventional way of quadrupole operation the ions are not trapped in between the rods but fly alongside them. However, it is also possible to trap ions in between the quadrupole rods for a certain amount of time and detect them by radial ejection (Fig. 23) [44], The relatively large volume of ion 

Storage allows more ions to be trapped than in a conventional 3D-IT instrument (see the following text). This, together with the axial ion detection, significantly increases the sensitivity of ion detection. Therefore, LTQ mass analyzers are more and more often used in areas where sensitivity is a crucial issue, such as pharmacokinetics and proteomics (including, e.g., posttranslational modification studies). 

Interaction with electromagnetic fields three-dimensional quadrupole ion trap (3D QIT) analyzers 

The 3D QIT instruments have played and still play a revolutionary role in high-throughput mass spectral analyses. They are literally work horses that can operate in a 24/7 mode. Instrument maintenance is easy and not time-consuming. Qne disadvantage is that usually oidy unit resolution is achievable, but this drawback is overshadowed by the easy use for tandem MS/MS experiments (i.e., structural investigation, including, e.g., peptide sequencing that is fundamental for proteomics studies). 

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