Characterization of a serial array of miniature cylindrical ion trap mass analyzers

Two small (5 mm internal radius) cylindrical ion traps (CITs) are arranged in series and operated using a single ion source, detector and radio frequency (rf) trapping signal. Ions are trapped in the first CIT and later transferred to the second by applying a direct current (dc) pulse to the endcap electrode of the first trap. This process is facilitated if a second, appropriately timed, retarding dc pulse is applied to the exit endcap electrode of the second trap. Mesh endcaps are used for the CITs to increase the number of ionizing electrons entering the trap and to maximize the transfer efficiency and detected signal. The transfer efficiency is dependent on the amplitude of the dc potential applied to eject the ions from the first trap, the amplitude of the dc potential applied to retain the ions in the second trap, and the period during which the retarding potential is applied. The amplitude and phase of the rf also affect the transfer process. Ions that readily dissociate upon collision have low transfer efficiencies; more stable ions can be transferred with up to 50% efficiency. Copyright 1999 John Wiley & Sons, Ltd.