Periodic field focusing ion mobility spectrometer
AssigneesThe Texas A&M University System, Ionwerks, Inc.
InventorsKent J. Gillig, David H. Russell
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Abstract
This invention is generally in the field of improved ion mobility spectrometry. The improvement lies in the use of periodic focusing electric fields that minimize the spatial spread of the migrating ions by keeping them in a tight radius about the axis of travel. The resulting enhancement in sensitivity is accomplished without a concomitant loss in resolution as would normally be expected when non-linear fields are used.
Claims27
An apparatus for separating and analyzing ions, comprising:
- an ion source to generate ions;
- an ion mobility chamber positioned to receive the ions from the ion source and capable of producing a periodic focusing electric field wherein the ion mobility chamber comprises:
- a plurality of outer ring electrodes;
- a plurality of outer ring inter-electrode gaps coupled to the outer ring electrodes;
- a plurality of inner ring electrodes coaxial with the outer ring electrodes and equally spaced to form an inner drift tube wherein the ratio of the drift tube diameter to the electrode width of any individual inner ring electrode is less than four;
- and,
- a resistor chain coupled to the outside of the ion mobility chamber to apply a potential to both the outer and inner ring electrodes;
- an endplate coupled to the ion mobility chamber, the endplate having an ion aperture to expel the ions;
- a plurality of lenses coupled to the ion aperture;
- a plurality of electrostatic steering plates coupled to the lenses;
- and,
- a detector coupled to the lenses.
An apparatus for separating and analyzing ions, comprising:
- an ion source to generate ions;
- an ion mobility chamber positioned to receive the ions from the ion source and capable of producing a periodic focusing electric field wherein the ion mobility chamber comprises:
- a plurality of ring electrodes equally spaced to form a drift tube;
- a plurality of inter-electrode gaps adjacent to the ring electrodes wherein the ratio of the drift tube diameter to the electrode width of any individual ring electrode is less than four;
- and,
- a resistor chain coupled to the outside of the ion mobility chamber to apply a potential to the ring electrodes;
- an endplate coupled to the ion mobility chamber, the endplate having an ion aperture to expel the ions;
- a plurality of lenses coupled to the ion aperture;
- a plurality of electrostatic steering plates coupled to the lenses;
- and,
- a detector coupled to the lenses.
A method of separating and analyzing ions in the presence of a gas comprising the steps of:
- generating ions from an ion source;
- separating ions in terms of their mobility using an ion mobility chamber capable of producing a periodic focusing electric field, wherein the ion mobility chamber comprises a plurality of inner ring electrodes coaxial with a plurality of outer ring electrodes and equally spaced to form an inner drift tube wherein the ratio of the drift tube diameter to the electrode width of any individual inner ring electrode is less than four;
- and,
- detecting the ions.
A method for transporting ions in the presence of a gas comprising:
- transporting ions in a periodic focusing electric field;
- said field being formed in an ion mobility chamber, said ion mobility chamber comprising a plurality of inner ring electrodes coaxial with a plurality of outer ring electrodes and equally spaced to form an inner drift tube wherein the ratio of the drift tube diameter to the electrode width of any individual inner ring electrode is less than four;
- increasing the transmission efficiency of the ions from a high pressure source to high vacuum.
Dependencies are inferred from the claim text.