One preowned Smith Detection Model 400B-LS, Mfg 2006; Icon Mobility Spectrometry (IMS) a solid or liquid sample is introduced to the analyzer by thermal desorption or direct injection. The resultant vapors are swept in through the inlet by the carrier gas and ionized. The product ions are gated into the drift tube and accelerated by an electric field toward the detector. Air flows through the drift tube in a direction counter to the electric field. Drift times depend on the size, shape, and mass of the analyze and range from about 3 to 50 milliseconds.