How to Increase Further the Resolving Power of the Ultrahigh Magnetic Field FT ICR Instruments? The New Concept of the FT ICR Cell–the Open Dynamically Harmonized Cell as a Part of the Vacuum System Wall

Abstract

FT ICR mass spectrometry continues to be the leader in the resolving power among all mass spectrometry methods. With the introduction of the dynamically harmonized FT ICR cell, it has become possible to achieve the resolving power of more than 10 million at m/q = 1000 with moderate magnetic fields of about 7 T. A further increase in the mass resolving power is desirable mainly for two reasons: with this we are increasing the number of resolved components in analyses of complex mixtures (like oil and natural organic matter (NOM)) and increasing the number of the mass of molecules for which a fine structure can be resolved. In recent years, some attempts have been made to further increase the mass resolving power by increasing the magnetic field and using the multielectrode detection method. An increase in the magnetic field to 21 T did not show a proportional increase in the mass resolving power. Likely, the reason for this is an insufficiently high vacuum to satisfy the requirement of an increase in the mean free path of ions with the increasing magnetic field power. We offer a new design for the FT ICR cell and the whole mass spectrometer, in which an open, dynamically harmonized FT ICR cell is integrated into a vacuum system with the outer surfaces of the cell electrodes at atmospheric pressure. In this design, the trap electrodes are the walls of the vacuum system and have the minimized active surfaces by combining the vacuum system surface and the cell surface into one. In this design, the pumping process is accelerated, and the factor of insufficient vacuum in FT ICR mass spectrometers with an ultrahigh magnetic field is eliminated.

Proteomes Are of Proteoforms: Embracing the Complexity

“…A high vacuum in the ICR cell is therefore required for optimal function [ 162 , 165 , 166 ]. Recently, a concept was developed for a modified dynamically harmonized cell with a new “zigzag” ion trap configuration, which can improve the vacuum by decreasing the surface area of the cell and incorporating the vacuum tube directly into the working region of the cell however, this has not yet been implemented in an FTICR-MS so the practicality of this new cell remains to be demonstrated [ 167 ]. Additional disadvantages of the FTICR include its extremely high upfront and maintenance cost due to the requirement of cryogenic cooling for its magnets [ 168 ].…”

Generalization of an Open Dynamically Harmonized Cell for Ultrahigh FT ICR Resolution

“…We present a generalization class of “open dynamically harmonized cells”. The electric potential inside these cells can be as close to harmonic as needed, as will be shown from further analysis analysis of the electric field inside such cells analysis of the electric field inside previously presented open DHC as a particular case …”

“…The new cell modification inherits the construction principles from the cell, presented in the previous work. 5 So we first reintroduce this previously described cell and then highlight the idea of the modification and finally show the new construct.…”

“…where I 0 is the modified Bessel function of the first kind and zero order and f ( ) is the Fourier transform defined as (We have described this standard technique in a bit more detail in the Supporting Information for the previous article. 5 ) The Fourier transform for f(x) can be easily taken separately for areas |z| < z 0 , z 0 ≤ |z| < z 1 , |z|≥ z 1 .…”

Molecular Characterization of Fossil and Alternative Fuels Using Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry: Recent Advances and Perspectives

“…From the application point of view, the resolution and the price of the instrument are a contradiction, and a new balance may need to be determined. Improved resolving power is expected with the new design of the ICR cell …”