ION MOBILITY SPECTROMETER COMPRISING TWO DRIFT CHAMBERS

摘要

An ion mobility spectrometer has two drift chambers (11) and (12) and a c ommon, doped reaction region (2). Each drift chamber includes an ion modifie r (14) and (24), such as one that fragments the doped ions by a high electri cal field. One of the drift chambers (11) is doped and the other (12) is und oped. In this way, the dopant adducts are removed by the modification proces s b.mu.t then recombine with dopant only in the doped chamber.(11) so that d ifferent outputs are produced by the two drift chambers.