Performance of Orbitrap Mass Analyzer at Various Space Charge and Non-Ideal Field Conditions: Simulation Approach

Abstract

The orbital trap mass analyzer provides a number of unique analytical features along with inevitable limitations as an electrostatic instrument operating in high space charge regimes resulting in systematic measured frequency errors as an effect of stored ion clouds on the trap field and each other effect of non-ideal machining the trap electrodes, effect of injection slot, effect of real versus theoretical trap dimensions, etc. This paper deals with determining the influence of the space charge effect and imperfection of the electrostatic field on the motion of ion ensembles in the orbital trap. We examine effects of theoretically modeled non-harmonicity of the electrostatic potential and the number of confined ions on stability of coherent ion motion in the trap that determines the frequency shifts of axial ion oscillation. Three different Orbitrap geometries were considered: geometry close to preproduction Orbitrap, close to standard Orbitrap, close to high field Orbitrap. Frequency shifts for m/z=500 and for charge state +23 of cytochrome c isotopic cluster particles with 10 4 -6*10 6 elemental charges in the trap were considered. Refined spectra were calculated using the filter diagonalization method proposed by Mandelshtam et al. and applied to mass spectrometry by O'Connor and Aizikov.

Preliminary Figures of Merit for Isotope Ratio Measurements: The Liquid Sampling-Atmospheric Pressure Glow Discharge Microplasma Ionization Source Coupled to an Orbitrap Mass Analyzer

“…Likewise, in all forms of trapping MS, sensitivity is limited when non-analyte ions make up a large fraction of the ion population; limiting the number of analyte ions that can be effectively trapped and analyzed (i.e., space charge effects) [28][29][30][31][32][33]. Finally, regardless of the resolving power of the mass analyzer, it is always beneficial to remove species that simply add spectral complexity.…”

“…The potential deleterious effects of high ion densities in trapping-type mass analyzers are well documented [28][29][30][31][32][33]36]. Space-charge effects due to overfilling of traps can result in suppression of anticipated signal levels and corresponding intra-species ratios, broadening in the mass/ frequency domains, and shifts in apparent ion masses.…”

Fast image–charge calculations for multi-particle simulations in FT-ICR analyzer cells of arbitrary geometry

“…Multi-particle simulations provide a useful approach for studying collective ion motion in an FTICR analyzer cell, and to accurately model the influence of subtle effects such as spacecharge and ion-image charge interactions [1][2][3][4][5]. Simulations provide the ability to test the effects of parameters that are difficult to control experimentally such as the precise number and spatial distribution of ions in an analyzer cell [6].…”

Accelerated Simulation Study of Space Charge Effects in Quadrupole Ion Traps Using GPU Techniques

“…Its influence on ion cloud spatial distribution and mass shift in 3D quadrupole ion traps have been studied using laser tomography methods [23][24][25]. The relationships between space charge effects and ion trapping capacity, isolation efficiency, fragmentation efficiency, mass discrimination and MS resolution have also been investigated in linear ion traps [21,22,26,27], as well as in a digital ion trap [28,29], Fourier transform ion cyclotron resonance (FT-ICR) cells [17,[30][31][32] and Orbitraps [8,[33][34][35].…”

“…With the help of parallel computation techniques, the interactions among 1024 ions in a FT-ICR cell have been simulated [51,52]. Particle-in-cell approaches have also been introduced to model the coulombic ion-ion interactions and their effect on image charges for relatively large number of ions in FT-ICR cells [46,53] and Orbitrap [35]. The accuracy of this method was claimed to be limited by the ion density and the cell dimension [53].…”