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US 5,847,386 AGranted
Spectrometer with axial field
AssigneeMDS Inc.
InventorsBruce A. Thomson, Charles L. Jolliffe
Life of this patent
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AssigneeMDS Inc.
InventorsBruce A. Thomson, Charles L. Jolliffe
Estimating the term…
In a mass spectrometer, typically a quadrupole, one of the rod sets is constructed to create an axial field, e.g. a DC axial field, thereon. The axial field can be created by tapering the rods, or arranging the rods at angles with respect to each other, or segmenting the rods, or by providing a segmented case around the rods, or by providing resistively coated or segmented auxiliary rods, or by providing a set of conductive metal bands spaced along each rod with a resistive coating between the bands, or by forming each rod as a tube with a resistive exterior coating and a conductive inner coating, or by other appropriate methods. When the axial field is applied to Q0 in a tandem quadrupole set, it speeds passages of ions through Q0 and reduces delay caused by the need to refill Q0 with ions when jumping from low to high mass in Q1. When used as collision cell Q2, the axial field reduces the delay needed for daughter ions to drain out of Q2. The axial field can also be used to help dissociate ions in Q2, either by driving the ions forwardly against the collision gas, or by oscillating the ions axially within the collision cell.
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For use with an elongated set of conductive rods defining an elongated volume therebetween, said volume having a longitudinal axis, and a gas in said volume, a method of controlling fragmentation of ions in said volume comprising applying RF to said rods to control transmission of ions axially through said volume, establishing an axial electric field along at least a portion of said axis, and oscillating said axial electric field to cause fragmentation of ions in said volume.
For use with an elongated set of conductive members defining an elongated volume therebetween, said volume having a longitudinal axis, and an ion source for injecting ions into said volume with an axial velocity, a method of controlling passage of ions along said axis comprising applying RF to said elongated members to control transmission of ions axially through said volume, directing ions from said volume into a Time-of-Flight drift tube oriented at right angles to said axis, establishing an axial electric field along at least a portion of said axis, utilizing said axial electric field to reduce the axial velocity of said ions in said volume to approximately zero, and when said axial velocity has been reduced to approximately zero, then directing said ions into said Time-of-Flight drift tube.
For use with an elongated set of conductive members defining an elongated volume therebetween, said volume having a longitudinal axis, and a gas in said volume, a method of controlling fragmentation of ions in said volume comprising applying RF to said elongated members to control transmission of ions axially through said volume, and establishing an axial electric field along at least a portion of said axis, and controlling said axial field to drive said ions through said gas to dissociate ions in said volume.
For use with an elongated set of conductive members defining an elongated volume therebetween, said volume having a longitudinal axis and entrance and exit ends, and a drift gas in said volume, a method of providing mobility separation of ions in said volume comprising injecting ions into said entrance end of said volume, establishing an axial electric field along at least a portion of said axis to cause said ions to drift within said gas at velocities dependent on their mass to charge ratio while reducing diffusional loss of ions from said volume in the radial direction by collisional focussing in said gas, thereby producing separated groups of ions at said exit end, and mass analyzing desired ones of said separated groups of ions, thus to provide improved specificity to such mass analysis.
A method of mass analyzing a sample comprising:
Dependencies are inferred from the claim text.