Design and Implementation of a New Electrodynamic Ion Funnel
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- 作者：Taeman Kim ; Aleksey V. Tolmachev ; Richard Harkewicz ; David C. Prior ; Gordon Anderson ; Harold R. Udseth ; Richard D. Smith ; Thomas H. Bailey ; Sergey Rakov ; and Jean H. Futrell
- 刊名：Analytical Chemistry
- 出版年：2000
- 出版时间：May 15, 2000
- 年：2000
- 卷：72
- 期：10
- 页码：2247 - 2255
- 全文大小：177K
- 年卷期：v.72,no.10(May 15, 2000)
- ISSN：1520-6882
文摘
A new electrodynamic (rf) ion funnel has been developedand evaluated for use in the interface regions (at ~1-10Torr) of atmospheric pressure ion sources (e.g., electrospray ionization (ESI) for mass spectrometry). The ionfunnel consists of a ring electrode ion guide with decreasing i.d. and with a superimposed dc potential gradientalong the ring stack. The thicknesses of the ring electrodesand the spacings between them were reduced to 0.5 mmfrom 1.59 mm compared to those used for previousdesigns. The new ion funnel displays a significant improvement in low-mass transmission (m/z >200) andsensitivity compared to previous designs. The transmission efficiencies for electrosprayed peptides and proteins(ranging in mass from 200 to 17 000 Da) were typically50-60% of total incoming currents from a heated capillary inlet. The transmitted ion currents were a factor of30-56 greater than those of the standard interface forpeptide samples and a factor of 18-22 greater than thosefor protein samples. The sensitivity gains realized at theMS detector were somewhat lower, possibly due to spacecharge effects in the octapole ion beam guide followingthe ion funnel. The improved ion transmission propertiesresult primarily from the use of reduced spacings betweenring electrodes. We also show that the ion funnel can beoperated in two different modes, one using low-rf-amplitude scans, allowing fragile noncovalent complexes(as well as generally undesired adducts) to be transmitted,and the other using high-rf-amplitude scans, providinggreater collisional activation and more effective adductremoval (or the dissociation of lower m/z species).