A closed ion source with a cylindrical repeller for sensitivity enhancement in quadrupole mass spectrometry

Abstract

Sensitivity improvement has been achieved for a quadrupole mass spectrometer by replacing the flat repeller of a conventional ion source with a cylindrical repeller. Computer simulation of ion trajectories in the ion source demonstrated that ions were focused into the center of the ion lens with the cylindrical repeller but that ions were defocused with the flat repeller. Ion sources with the two repellers were tested for performance comparison using both a laboratory-built mass spectrometer and a commercial mass spectrometer. The cylindrical repeller showed about threefold sensitivity enhancement at lower repeller voltages across the mass range from 69to502m∕z.

Characterization and Improvement of Signal Drift Associated with Electron Ionization Quadrupole Mass Spectrometry

“…The use of a shorter ionization path was investigated by Kuhnke et al in 1994 . The use of a cylindrical repeller shape instead of a flat shape for improved ion beam focusing was reported by Park and Ahn . A new medium for EI, defined as a supermolecular beam interface, was introduced by the group of Amirav.…”