Patent ID: 7838821
Filing Date: 2010-11-23
Classification: G01N

Abstract:
1. An ion mobility spectrometer instrument comprising: a drift tube partitioned into a plurality of cascaded drift tube segments each defining an ion inlet at one end and an ion outlet at an opposite end, the plurality of cascaded drift tube segments further defining an ion elimination region between an ion outlet of each drift tube segment and an ion inlet of an adjacent drift tube segment, an ion source coupled to the ion inlet of a first one of the plurality of cascaded drift tube segments, a number, M, of electric field activation sources each operatively connected to one or more of the plurality of drift tube segments such that, when activated, each establishes a repulsive electric field in a different one of the first M ion elimination regions and in every following Mth ion elimination region, and also establishes an electric drift field in all remaining ion elimination regions and in all of the plurality of cascaded drift tube segments, and a control circuit configured to sequentially activate each of the number, M, of electric field activation sources for a time duration while deactivating the remaining number, M, of electric field activation sources a number of times to thereby cause only ions generated by the ion source that have a predefined ion mobility or range of ion mobilities to traverse the drift tube.