Ijims_6_2003_2.book

Jennifer L Neves, Paul E Haigh, , Ching Wu, William J McGann GE Ion Track, 205D Lowell Street, Wilmington, MA 01887, USA Introduction
electrospray interface. The ITMS detector wassheared off at the Faraday collector plate and detected commercial explosives such as TNT explosives, such as smokeless powders, have modified ITMS detector was mounted to the presented detection challenges. As seen in API1 assembly in place of the electrospray needle assembly block via a custom machined substances have been characterized using a mounting plate. A GE Ion Track VaporTracer was modified to supply the voltages required Itemiser 3 heated desorber was attached to negative mode using ITMS, but the identities of the detected ions were not determined. An ITMS detector interfaced to a commercially region were drawn through a heated capillary available quadrupole mass spectrometer (MS) (150° C) into the API1 interface, which was was used to analyze the ions detected for a differentially pumped to approximately 450 mTorr. A series of lenses and an octapole ion degradation products were seen for many of guide conveyed the ions to the ion lenses at the entrance to the quadrupole region. The differentiate between the various explosives.
The improvised explosives Bluedot smokeless approximately 4.9 x10-6 Torr. In order to produce an ITMS plasmagram for a particular nitroglycerin, TNT, and RDX were analyzed via generate an analog signal from the electron multiplier of the MS. The electron multiplierresponse was pre-amplified and read on an Experimental
oscilloscope that was triggered by the ITMS mass spectrometer by way of a Finnigan API1 fifteen nanograms of TNT, RDX, andWinchester and Bluedot smokeless powderswere introduced into the Itemiser 3 and ITMS- 1. Neves, J.L., Haigh, P., McGann, W.: Expanding the Capabilities of IMS Explosive Trace Detection. IJIMS Table 1: Difference Between Itemiser and ITMS-MS Ion Mobility Received for review July 8, 2003, Accepted July 25, 2003 2 - ITMS-MS Analysis of Smokeless Powder
by an M+2 peak, which confirms thatRDX formed a chlorinated speciesduring ionization. The ITMS-MSplasmagram for RDX is shown in Fig.
2.
62 for nitroglycerine (MW = 227)indicates a NO3 breakdown product. and Winchester smokeless powderswere: nitrocellulose, nitroglycerin,diphenyl-amine, ethyl centralite, rosinand poly-ester. The nitrocellulose andnitroglycerin are the explosivecomponents; the diphenylamine and Figure 3: MS Signal of RDX + Cl (close up) sample swabs as methanol solutionthat was allowed to evaporate. in the ion appearance time wasobserved on the ITMS-MS withrespect to the ion appearance timeobserved on a standard ITMSdetector (Itemiser 3) operating atthe same temperature (200° C)(Table 1). This is due to the time offlight between the capillary interfaceof the ITMS and the MS electronmultiplier.
m/z = 225.5 for TNT (MW = 227)(Fig. 1). It is assumed that TNTionized by proton abstraction, whichwould indicate a calibration offset ofm/z 0.5.
(MW = 222) at m/z 257. As seen infigure 3, the RDX MS peak is followed Copyright 2003 by International Society for Ion Mobility Spectrometry ITMS-MS Analysis of Smokeless Powder - 3
peak at 3.890 ms and a positive modepeak at 7.447 ms when introduced intoan Itemiser 3. for each smokeless powder was identicalto that for nitroglycerine. The positivemode MS peak for smokeless powderwas observed at m/z = 269 (Fig. 4).
The ITMS-MS plasmagram peakobserved for the m/z = 269 ion tailedextensively and had a poorly definedmaximum (Fig. 5). centralite (MW = 268) was introducedinto the Itemiser 3. The same positivemode peak appeared on the Itemiser(Fig 6) as was observed for thesmokeless powders, confirming ethyl detector to a mass spectrometer as a tool for the confirmatory identification of plasmagram The identification of ethyl centralite as Conclusion
the compound detected in positive modeITMS for smokeless powders could help to detection of common explosives has relied on from other explosives that are identified by a the use of empirically correlating plasmagram peaks to substances of interest. This workdescribes the first coupling of an ITMS Copyright 2003 by International Society for Ion Mobility Spectrometry

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