US 5,420,424 AGranted

Ion mobility spectrometer

AssigneeMine Safety Appliances Company

InventorsByron L. Carnahan, Alexander S. Tarassov

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Abstract

An ion mobility spectrometer having a housing with an analyzer positioned therein. The analyzer includes first and second longitudinally spaced apart electrodes which are preferably cylindrical in configuration. The space between the electrodes defines an analytical gap which is in communication with a source of carrier gas. An ionization source such as a .beta.-emitter or corona discharge is juxtaposed with the analytical gap and source of sample media and includes an ion aperture for ions to enter said gap. The spectrometer includes an ion detector for measuring ions. An electrical controller connected to the first and second electrodes for impressing a first direct potential and second periodic asymmetrical potential capable of creating a transverse electrical field therebetween during the flow of carrier gas in the analytical gap. Preferably, a third low voltage ripple potential is impressed in series with the first two potentials. A third electrode, normally the ionization source, for electrically migrating the ions formed by the source into the analytical gap is positioned proximate to the ion aperture.

Claims18

Dependent claims

An ion mobility spectrometer comprising:

a. a housing having at least one inlet for communication with a sample media and at least one outlet,
b. an analyzer positioned within said housing comprising:
i. at least first and second longitudinally spaced apart electrodes, said space between said electrodes defining a longitudinal analytical gap, said gap being in communication with a source of carrier gas for flow therethrough,
ii. an ionization source juxtaposed with said analytical gap and in communication with said inlet for ionization of sample media,
iii. an ion aperture defining an opening between said ionization source and said analytical gap,
iv. a third electrode positioned proximate to said ion aperture,
v. at least one outlet aperture from said analytical gap remote from said ion aperture,
vi. an ion detector for measuring ions from said analytical gap and spaced from said electrodes, and
vii. an electrical controller connected to said electrodes for impressing:
A. direct current potentials to said first, second and third electrodes, and
B. a periodic asymmetrical potential to said first and second electrode, said potentials capable of creating a transverse electric field therebetween during the flow of carrier gas in the analytical gap.

8 more elements

Dependencies are inferred from the claim text.