US 6,661,003 B2 · Dielectric capillary high pass ion filter

Abstract

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.

Claims24

Dependent claims

A conduit for transporting ions from an ionization chamber containing gas at relatively high pressure to a mass analyzer chamber containing gas at a relatively low pressure, comprising:

(a) a tube of dielectric material, having an upstream end adjacent said ionization chamber and a downstream end adjacent said mass analyzer chamber, an upstream opening at said upstream end, a downstream opening at said downstream end and a bore extending from said upstream opening to said downstream opening, said bore enabling a gas flow assisted movement of ions to pass from said ionization chamber to said mass analyzer chamber;
(b) a first electrode at said upstream end;
(c) a second electrode at said downstream end;
(d) a third electrode located between said upstream end and said downstream end;
and
(e) a source of electric potential connected to each of said first, second and third electrodes for creating an electric field having a first portion between said first electrode and said second electrode and a second portion between said second electrode and said third electrode, said first portion having a voltage gradient that is steeper than that of said second portion, whereby said electric field is capable of opposing said gas flow assisted movement of ions within said bore and the steeper voltage gradient along said first portion is capable of retarding downstream movement of ions having drift velocities below a selected lower limit through and out from said bore.

3 more elements

A mass spectrometer comprising:

(a) an ionization chamber containing gas at relatively high pressure;
(b) a mass analyzer chamber containing gas at a relatively low pressure;
(c) a tube of dielectric material extending from said ionization chamber to said mass analyzer chamber, said tube having an upstream end adjacent said ionization chamber, a downstream end adjacent said mass analyzer chamber, an upstream opening at said upstream end, a downstream opening at said downstream end and a bore extending from said upstream opening to said downstream opening, said bore enabling a gas flow assisted movement of ions to pass from said ionization chamber to said mass analyzer chamber;
(d) a first electrode at said upstream end;
(e) a second electrode at said downstream end;
(f) a third electrode between said upstream and downstream ends;
and
(g) a source of electric potential connected to each of said first, second and third electrodes for creating an electric field having a first portion between said first electrode and said second electrode and a second portion between said second electrode and said third electrode, said first portion having a voltage gradient that is steeper than that of said second portion, whereby said electric field is capable of opposing said gas flow assisted movement of ions within said bore and the steeper voltage gradient along said first portion is capable of retarding downstream movement of ions having drift velocities below a selected lower limit through and out from said bore.

5 more elements

Dependencies are inferred from the claim text.

Dielectric capillary high pass ion filter

Life of this patent

Dielectric capillary high pass ion filter

Life of this patent

Abstract

Claims24