Ion mobility spectrometer

Claim 1

An ion mobility spectrometer comprising: a substantially cylindrical spectrometer tube having an ion shutter within said tube defining a reaction chamber and a drift chamber, both of said chambers being at atmospheric pressure, said drift chamber including a plurality of metallic rings concentrically aligned and extending from the ion shutter to a first end of the spectrometer tube, said first end having a collector plate and an inlet in communication with ambient air; detector means in communication with said collector plate for detecting and analyzing the drift velocity of ions arriving at said collector plate; means for applying a potential gradient across the tube; means for applying a potential gradient across said ion shutter; means for producing product ions from a sample within said reaction chamber; and means for causing air to pass through said inlet into said drift chamber and reaction chamber; whereby said air entering through said inlet acts as both a sample and carrier gas that undergoes molecular reactions in the reaction chamber to produce product ions and said air also acting as a drift gas that collides with the product ions passing through said ion shutter into the drift chamber causing said product ions to arrive at the collector plate having a drift velocity detected and analyzed by said detector means.