Explosives detection using differential ion mobility spectrometry
System for control of ion species behavior in a time-varying filter field of an ion mobility-based spectrometer to improve species identification for explosives detection.
1. A method for identifying an analyte with explosive characteristics in a differential mobility spectrometer (DMS), comprising:
supplying at least one analyte with explosive characteristics to a flow channel of the DMS;
selecting at least one dopant having an electron affinity;
delivering an ionized flow of the at least one analyte and the at least one dopant to the flow channel;
applying an asymmetric RF voltage and a compensation voltage to filter electrodes located on or in the flow channel;
detecting at least one signal corresponding to the ionized flow passing between the filter electrodes; and
identifying said analyte based on the at least one detected signal.
2. The method of claim 1 , and further comprising the step of selecting an analyte and adjusting the operating pressure in the flow channel according to the selection.
3. The method of claim 1 , wherein the electron affinity of the at least one dopant is smaller than an electron affinity of the analyte to be identified.
4. The method of claim 1 , wherein the at least one analyte passes through a gas chromatograph (GC) before being supplied to the flow channel.
5. The method of claim 1 , wherein the dopant is selected from the group consisting of methylene bromide (CH 2 Br 2 ), methylene chloride (CH 2 Cl 2 ), chloroform (CHCl 3 ), water (H 2 O), methanol (CH 3 OH), and isopropanol.
6. The method of claim 1 , wherein the analyte is selected from the group consisting of HMX, Tetryl, PETN, RDX, NG, TNT, EGDN, DNT, o-MNT, p-MNT, DMNB, TATP, HMTD and AN.