title: Experimental evaluation and optimization of structures for lossless ion manipulations for ion mobility spectrometry with time-of-flight mass spectrometry.
abstract: We report on the performance of structures for lossless ion manipulation (SLIM) as a means for transmitting ions and performing ion mobility separations (IMS). Ions were successfully transferred from an electrospray ionization (ESI) source to the TOF MS analyzer by means of a linear SLIM, demonstrating lossless ion transmission and an alternative arrangement including a 90° turn. First, the linear geometry was optimized for radial confinement by tuning RF on the central "rung" electrodes and potentials on the DC-only guard electrodes. Selecting an appropriate DC guard bias (2-6 V) and RF amplitude (≥160 V(p-p) at 750 kHz) resulted in the greatest ion intensities. Close to ideal IMS resolving power was maintained over a significant range of applied voltages. Second, the 90° turn was optimized for radial confinement by tuning RF on the rung electrodes and DC on the guard electrodes. However, both resolving power and ion transmission showed a dependence on these voltages, and the best conditions for both were >300 V(p-p) RF (685 kHz) and 7-11 V guard DC bias. Both geometries provide IMS resolving powers at the theoretical limit (R ~ 58), showing that degraded resolution from a "racetrack" effect from turning around a corner can be successfully avoided, and the capability also was maintained for essentially lossless ion transmission.
authors.affiliation: Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory , 3335 Innovation Ave. (K8-98), P.O. Box 999, Richland, Washington 99352, United States.
authors.forename: Ian K
authors.initials: IK
authors.lastname: Webb
authors.forename: Sandilya V B
authors.initials: SV
authors.lastname: Garimella
authors.forename: Aleksey V
authors.initials: AV
authors.lastname: Tolmachev
authors.forename: Tsung-Chi
authors.initials: TC
authors.lastname: Chen
authors.forename: Xinyu
authors.initials: X
authors.lastname: Zhang
authors.forename: Randolph V
authors.initials: RV
authors.lastname: Norheim
authors.forename: Spencer A
authors.initials: SA
authors.lastname: Prost
authors.forename: Brian
authors.initials: B
authors.lastname: LaMarche
authors.forename: Gordon A
authors.initials: GA
authors.lastname: Anderson
authors.forename: Yehia M
authors.initials: YM
authors.lastname: Ibrahim
authors.forename: Richard D
authors.initials: RD
authors.lastname: Smith
mesh_terms: D004560:Electricity; D004566:Electrodes; D007477:Ions / Q000737:chemistry; D011846:Radio Waves; D021241:Spectrometry, Mass, Electrospray Ionization / Q000295:instrumentation* / Q000379:methods
chemical_list: D007477:Ions