Abstract
Mass selective axial ejection of ions from linear quadrupoles with added octopole fields is described. Quadrupoles with 2.0% and 2.6% added octopole fields have been tested and compared with a conventional quadrupole. The effects of trapping ions at different q values, excitation voltage, scan direction, balanced and unbalanced rf voltages on the rods, and dc applied between the rods have been investigated. The highest scan speeds and best resolution are obtained with resonant excitation and ejection at high q (q=0.8). With axial ejection, the quadrupole with a 2.0% added octopole field provides mass resolution and ejection efficiencies similar to a conventional rod set. Quadrupole, dipole, and simultaneous dipole—dipole excitation between the x and y rod pairs were compared, and no advantage was found with quadrupole or dipole—dipole excitation. The effects of scan speed were investigated and a resolution at half height of about 1600 is possible at scans speed up to 5000 Th/s.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Church, D. A. Storage-Ring Ion Trap Derived from the Linear Quadrupole Radiofrequency Mass Filter. J. Appl. Phys. 1969, 40, 3127–3134.
Douglas, D. J.; Frank, A. J.; Mao, D. M. Linear Ion Traps in Mass Spectrometry. Mass Spectrom. Rev. 2004, 23, 1–29.
Hager, J. W. Performance Optimization and Fringing Field Modifications of a 24-mm Long RF-Only Quadrupole Mass Spectrometer. Rapid Commun. Mass Spectrom. 1999, 13, 740–748.
Hager, J. W. A New Linear Ion Trap Mass Spectrometer. Rapid Commun. Mass Spectrom. 2002, 16, 512–526.
Wang, Y.; Franzen, J.; Wanczek, K. P. The Nonlinear Resonance Ion Trap. 2: A General Theoretical Analysis. Int. J. Mass Spectrom. Ion Processes. 1993, 124, 125–144.
Wang, Y.; Franzen, J. The Nonlinear Ion Trap. 3: Multipole Components in Three Types of Practical Ion Trap. Int. J. Mass Spectrom. Ion Processes. 1994, 132, 155–172.
Sudakov, M.; Douglas, D. J. Linear Quadrupoles with Added Octopole Fields. Rapid Commun. Mass Spectrom. 2003, 17, 2290–2294.
Michaud, A. L.; Frank, A. J.; Ding, C.; Zhao, X. Z.; Douglas, D. J. Ion Excitation in a Linear Quadrupole Ion Trap with an Added Octopole Field. J. Am. Soc. Mass Spectrom. 2005, 16, 835–849.
Ding, C. F.; Konenkov, N. V.; Douglas, D. J. Quadrupole Mass Filters with Octopole Fields. Rapid Commun. Mass Spectrom. 2003, 17, 2495–2502.
Campbell, J. M.; Collings, B. A.; Douglas, D. J. A New Linear Ion Trap Time-of-Flight System with Tandem Mass Spectrometry Capabilities. Rapid Commun. Mass Spectrom. 1998, 12, 1463–1474.
Sudakov, M.; Konenkov, N.; Douglas, D. J.; Glebova, T. Excitation Frequencies of Ions Confined in a Quadrupole Field with Quadrupole Excitation. J. Am. Soc. Mass Spectrom. 2000, 11, 10–18.
Hager, J. W.; Londry, F. System and Method for Modifying the Fringing Field of a Radio Frequency Multipole; US Patent 7019290, 2006.
Dawson, P. H. Principles of Operation. In Quadrupole Mass Spectrometry and Its Applications; Dawson, P. H., Ed.; AIP Press: Woodbury, N.Y., 1995, p 21.
Douglas, D. J.; Glebova, T. A.; Konenkov, N. V.; Sudakov, M. Y. Spatial Harmonics of the Field in a Quadrupole Mass Filter with Circular Electrodes. Tech. Phys. 1999, 44, 1215–1219.
Goeringer, D. E.; Whitten, W. B.; Ramsey, J. M.; McLuckey, S. A.; Glish, G. L. Theory of High-Resolution Mass-Spectrometry Achieved Via Resonance Ejection in the Quadrupole Ion Trap. Anal. Chem. 1992, 64, 1434–1439.
Williams, J. D.; Cox, K. A.; Cooks, R. G.; McLuckey, S. A.; Hart, K. J.; Goeringer, D. E. Resonance Ejection Ion-Trap Mass-Spectrometry and Nonlinear Field Contributions—the Effect of Scan Direction on Mass Resolution. Anal. Chem. 1994, 66, 725–729.
Author information
Authors and Affiliations
Corresponding author
Additional information
Published online November 12, 2007
Rights and permissions
About this article
Cite this article
Moradian, A., Douglas, D.J. Mass selective axial ion ejection from linear quadrupoles with added octopole fields. J. Am. Soc. Spectrom. 19, 270–280 (2008). https://doi.org/10.1016/j.jasms.2007.10.025
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1016/j.jasms.2007.10.025