AN IMPROVED ION GUIDE FOR EXTERNAL ION INJECTION IN GLOW-DISCHARGE FOURIER-TRANSFORM ION-CYCLOTRON RESONANCE MASS-SPECTROMETRY

To improve the existing ion transport optics of our glow discharge (GD )-Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometer , we simulated several ion trajectories between the GD source region a nd the ICR analyzer cell. These calculations suggested that a number o f simple improvements, including the use of an ion flight tube and an electrically isolated conductance limit, would increase the efficiency of ion transfer through the fringing fields of the FT-ICR superconduc ting magnet and into the ICR analyzer cell. Ion beam intensity was mon itored as a function of the distance between the GD source and the ana lyzer cell before and after implementing these improvements. A twentyf old improvement in the transport efficiency, as well as a fifteenfold enhancement in detected FT-ICR signals, was observed.