Abstract
Focusing and transmission are important characteristics of ion transportation in mass spectrometric applications. An ion guide device is an essential component in a mass spectrometer, especially when chemical ionization is employed. We present a conical octopole ion guide and its comparison with a parallel counterpart for simulating the ion trajectories through the ion guide and the quadrupole mass analyzer. Ion trajectory simulations using SIMION 8.0 were performed to evaluate the performance of both conical and parallel octopole ion guides and the overall ion transmission through combining the octopole ion guide and the quadrupole mass analyzer in the mass spectrometer. Through the simulations, parameters that control the ion guide were optimized for the focus and transport of weakly bonded cluster ions, including the DC bias voltage, the frequency and the amplitude of the sine wave applied to the guide. The results from ion trajectory simulations showed that the ion beam can be highly focused from initially 10mm down to 2mm in diameter for the conical octopole ion guide. The transmission efficiencies are dependent on the mass of the ion, the frequency and amplitude of the radiofrequency waveform applied to the octopoles. The simulated overall transmission efficiencies of the conical ion guide are consistent with the observed sensitivities from the previously reported calibration experiments in the low-mass region but are much higher than those in the high-mass region (i.e., masses greater than 400amu). The simulations showed that the conical octopole ion guide can efficiently transport ions with high focusing through differentially pumped vacuum chambers. However, the overall transmission efficiencies of the conical octopole ion guide are in general lower than the parallel one when combined with the quadrupole mass analyzer based on the assumed exponential pressure gradient along the axial of the octopole ion guide.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
