Three Dimensional Many Particle Simulation for Peak Coalescence and Ion Loss Resulting from Coulomb Interactions between Ions in an FT-ICR Mass Spectrometer

Abstract

A three dimensional many particle model is proposed for computer simulation of Fourier transform ion cyclotron resonance (FT-ICR) mass spectra. The model is relatively simple and includes Coulomb interactions between ions in an FT-ICR cell. FT-ICR mass spectra of CO⁺ and C₂H₄⁺ mixtures are simulated at CO⁺:C₂H₄⁺=1:1, 2:1, and 1:2 for low, medium, and high ion density. The Coulomb interaction at CO⁺:C₂H₄⁺=1:1 appears to be the most significant from the results on peak coalescence phenomenon. The simulation performance is estimated through comparison with Mitchell's simulation model. Ion loss due to the space charge effect during detection period is investigated for ions of the same (C₂H₄⁺), two different (C₂H₄⁺: m/z 50.0=1:1) and two closely spaced (CO⁺:C₂H₄⁺=1:1) mass-to-charge ratios as a function of initial ion population. In the case of different m/z ions, particularly for closely spaced m/z ions, the ion loss ratio increases considerably with initial ion population. On the other hand, for the same m/z ions no significant ion loss occurs even at a large initial ion population.