Ion trajectories through the input ion optics of an inductively coupled plasma-mass spectrometer

A commercial program (MacSimion) has been used to model the einzel lens and bessel box input lens system of an inductively coupled plasma-mass spectrometer (ICP-MS). A number of plots are presented illustrating the effect of various lens voltages on ion trajectories. The trajectories are dependent on ion kinetic energy and since ion kinetic energy is mass dependent in ICP-MS, these plots clarify the mass dependence of ion lens voltage settings. Plots are also presented illustrating the interdependence of some lens voltage settings and how, in fact, different lens voltage settings can result in similar ion throughput. The model can be used to predict relative signal intensities for a range of ion masses as a function of lens potentials and these are shown to agree with experimentally measured data.