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US 6,486,469 B1Granted
Dielectric capillary high pass ion filter
AssigneeAgilent Technologies, Inc.
InventorsSteven M. Fischer, Robert K. Crawford, Charles W. Russ, IV
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AssigneeAgilent Technologies, Inc.
InventorsSteven M. Fischer, Robert K. Crawford, Charles W. Russ, IV
Estimating the term…
For delivery of ions from a higher pressure ion source to a mass analyzer operating at high vacuum, high pass ion filtration is effected within a dielectric capillary interface between the higher pressure ionization chamber and the lower pressure environment of a mass analyzer, by application of electrical potentials to end electrodes and to at least one electrode associated with the dielectric capillary between the ends, to create an end-to-end electric field generally opposing gas flow-assisted movement of ions from the upstream end to the downstream end, and to create a steeper voltage gradient along an upstream portion than along a downstream portion of the capillary. The voltage gradient along the steeper upstream portion of the capillary is sufficiently steep to cause ions having drift velocities below a lower limit to stall within the capillary. The respective potentials may be adjusted to increase the steepness of the upstream voltage gradient to increase the drift velocity lower limit.
A conduit for transporting ions from a higher pressure ion source to a mass analyzer at high vacuum in mass spectrometry apparatus, comprising a tube constructed of a dielectric material and defining a capillary bore extending from end to end, wherein the tube has an end electrode associated with each end and at least one additional electrode associated with the tube between the ends, and wherein the electrodes are connected to a source of electrical potential,
A method for delivering ions from a higher pressure ionization chamber to a mass analyzer operating at high vacuum employs a conduit that includes a tube constructed of a dielectric material and defining a capillary bore from end to end and having an electrode associated with each end and at least one additional electrode associated with the tube between the ends, the method comprising applying electrical potentials to the electrodes to generate an end-to-end electric field having a voltage gradient that is steeper along an upstream portion of the conduit than along a downstream portion of the conduit such that:
A method for effecting high pass ion filtration within a dielectric capillary interface between a higher pressure ionization chamber and the lower pressure environment of a mass analyzer in mass spectrometry apparatus, the method comprising applying electrical potentials to end electrodes and to at least one electrode associated with the dielectric capillary between the ends to create an end-to-end electric field generally opposing the gas flow-assisted movement of ions from the upstream end to the downstream end, and to create a steeper voltage gradient along an upstream portion than along a downstream portion of the capillary, whereby the voltage gradient along the steeper upstream portion of the capillary retards the downstream movement within the capillary of ions having drift velocities below a selected lower limit.
Dependencies are inferred from the claim text.