| US 7,601,952 B2 | ||
| Method of operating a mass spectrometer to provide resonant excitation ion transfer | ||
| Jim Hager, Mississauga (Canada); and Bruce Thomson, Toronto (Canada) | ||
| Assigned to MDS Analytical Technologies, a business unit of MDS Inc., Concord, Ontario (US); and Applied Biosystems, Inc., Framingham, Mass. (US) | ||
| Filed on Jul. 17, 2007, as Appl. No. 11/778,954. | ||
| Claims priority of provisional application 60/807779, filed on Jul. 19, 2006. | ||
| Prior Publication US 2008/0017789 A1, Jan. 24, 2008 | ||
| Int. Cl. H01J 49/00 (2006.01) | ||
| U.S. Cl. 250—292 [250/290; 250/288; 250/282; 250/281] | 31 Claims |
| 1. A method of operating a mass spectrometer having a rod set, the rod set having a first end, a second end opposite to the
first end, and a longitudinal axis extending between the first end and the second end, the method comprising:
a) admitting ions into the rod set;
b) trapping at least some of the ions in the rod set by i) producing a first barrier field at a first end member adjacent
to the first end of the rod set, ii) producing a second barrier field at a second end member adjacent to the second end of
the rod set, and iii) providing an aggregate field comprising an RF field between the rods of the rod set;
c) selecting a first selected mass to charge ratio of a first group of ions in the ions;
d) determining a first excitement level of a selected characteristic of the aggregate field for the first group of ions;
e) adjusting the selected characteristic of the aggregate field to the first excitement level to resonantly excite the first
group of ions to mass selectively eject the first group of ions axially from the rod set past the barrier field; and,
f) maintaining the selected characteristic of the aggregate field at the first excitement level during an excitement time
interval wherein the excitation time interval is at least 1 millisecond.
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