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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
journal contribution
posted on 2020-12-23, 00:14 authored by Evgeny Nikolaev, Anton LioznovFT 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.