Abstract: A device for gas detection through ion mobility segregation by mobility ranges includes a flow tube through which a sample of atmospheric air with possible contaminant gases flow. Ions formed of gases in the air and the possible contaminant gases are segregated by ion mobility range in either a first, second or subsequent electric field positioned along the flow tube. The ions are collected on an anode or cathode of each electric field. The ions of the gases striking an anode or cathode by charge transfer induce a detection current, the measure of which indicates the presence of gases of interest. A method for detecting a gas by ion mobility segregation is also described.