Concentrating mass spectrometer ion guide, spectrometer and method
AssigneeIonics Mass Spectrometry Group Inc.
InventorsGholamreza Javahery, Lisa Cousins, Charles Jolliffe, Ilia Tomski
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Abstract
An ion guide includes multiple stages. An electric field within each stage guides ions along a guide axis. Within each stage, amplitude and frequency, and resolving potential of the electric field may be independently varied. The geometry of the rods maintains a similarly shaped field from stage to stage, allowing efficient guidance of the ions along the axis. In particular, each rod segment of the ith of stage has a cross sectional radius ri, and a central axis located a distance Ri+ri from the guide axis. The ratio ri/Ri and is substantially constant along the guide axis, thereby preserving the shape of the field.
Claims68
An ion guide, comprising n stages extending along a guide axis, each of said n stages comprising a plurality of opposing elongate conductive rod segments arranged about said guide axis,
- each of said elongate conductive rod segments of the ith of said n stages having a length li, a cross sectional radius ri, and a central axis a distance Ri+ri from said guide axis;
- a voltage source, providing a voltage having an AC component between two adjacent ones of said plurality of opposing elongate conductive rod segments of each of said stages to produce an alternating electric field to guide ions along said guide axis;
- wherein ri/Ri and is substantially constant along said guide axis and Ri for at least two of said stages are different.
An ion guide comprising a plurality of opposing elongate, at least partially conductive rod segments arranged about a guide axis to produce an alternating electric field therebetween, each of said elongate rod segments having a substantially circular cross-section having radius r(x) and centered at a position r(x)+R(x) from said guide axis, wherein x represents a position x along said guide axis, and wherein r(x)/R(x) is substantially constant for values of x along said guide axis.
A method of guiding ions of selected m/z ratios within an ion guide along a guide axis, said method comprising:
- providing a plurality of guide stages arranged along said guide axis;
- within each of said plurality of guide stages, generating an alternating electric field that guides said ions along said guide axis, and confines ions of selected m/z ratios within a radius about said guide axis in each of said stages,
- wherein the radius is sequentially reduced from stage to stage along said guide axis, and
- wherein at least one of the amplitude and frequency of said electric field within each stage, varies from the amplitude, frequency, and axial and resolving potential within an adjacent stage.
Dependencies are inferred from the claim text.