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

Abstract

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.

Geometry optimization for the cylindrical ion trap: field calculations, simulations and experiments

“…1 and it is expected that changing any of these parameters would cause a variation in the electric field strength inside the CIT. The geometry of CIT-0 as listed in Table 1 has been shown to give optimum performance [19]. Using the CIT-0 geometry as the basis, variations in the quadrupolar (A 2 ), octapolar (A 4 ) and dodecapolar (A 6 ) field contributions are calculated for a 10% increase of each geometrical parameter of the CIT-0.…”

“…One mass analyzer which has been miniaturized for fieldable instruments, the cylindrical ion trap (CIT), was originally used as an ion storage device [17], then developed as a mass analyzer [18], miniaturized to smaller sizes [9,13,19], and then implemented in a portable ion trap mass spectrometer [14,20]. A large amount of effort has been expended on the optimization of the CIT geometry to achieve unit or better mass resolution [13,15,16,18].…”

“…A large amount of effort has been expended on the optimization of the CIT geometry to achieve unit or better mass resolution [13,15,16,18]. Although a new geometry ion trap, the rectilinear ion trap (RIT), has been recently demonstrated to provide improved sensitivity [21], the CIT remains easier to fabricate, miniaturize and multiplex [15,19,22], and it represents the only simplified geometry ion trap to be commercialized.…”

Performance Evaluation of a Loeb-Eiber Mass Filter at 1 Torr

“…In contrast to TOFs, linear quadrupoles, and magnetic sectors [19], ion traps enjoy the ability to perform tandem mass spectrometry with a single mass analyzer [20]. The simplified geometry of a cylindrical ion trap in comparison to 3D ion traps has led to a significant research investment in the miniaturization of ion traps [21][22][23][24][25][26] and micro-fabricated ion trap arrays [27][28][29]. Lammert [30,31] and Austin [32][33][34] have studied toroidal ion traps of various geometries in an attempt to expand the quantitative dynamic range of ion traps in miniature and portable instruments.…”

Development of a palm portable mass spectrometer

“…For example, Whitten et al [12] have demonstrated a submillimeter size ion trap that resolves the isotope ratio of xenon, while Cooks et al have developed a micron size cylindrical ion trap [13]. Small size also reduces trapping capacity because of ion repulsion forces, and a multi-array of micro ion traps in various dimensions has been proposed to compensate for this loss of sensitivity [14,15].…”