SWIPE EXPERIMENTS FOR IMPROVED EXPLOSIVES DETECTION –
THE ROUTE TO BETTER SAMPLING OF PARTICLES
Raya Zach1, Eli Diga2, Edi Kaufman2, Zvi Goldbart2 and Yehuda Zeiri1
1
Department of Biomedical Engineering Ben-Gurion University, Beer-Sheva 84105, Israel and Division
of Chemistry, Nuclear Research Center, Negev, P.O. Box 9001 Beer-Sheva 84190, Israel
2
Rotem Industries Ltd, Analytical chemistry Services, Rotem Industrial Park, D.N. Arava 86800, Israel
Raya970@gmail.com; yehuda@bgu.ac.il
The low vapor pressure of most explosives lead to the requirement to detect them in their solid phase.
Numerous analytical methods have been developed for the detection of trace amounts of explosives,
including: ion mobility spectrometry (IMS), liquid chromatography (HPLC and LC-MS), mass
spectrometry (MS), desorption electron spray ionization mass spectrometry (DESI-MS) and others. The
detection limit in most methods is far below the one required by the present sampling methods. Hence,
improvement of sampling techniques is the main requirement to achieve more reliable detection of trace
amounts of explosives. One of the most widely used detection methods is based on IMS measurements
of samples collected by swipe. The swipe material, usually supplied by the manufacturer of the IMS,
consist of soft material (cloth) whose composition and texture is developed and optimized by the
manufacturer and supplier of the IMS.
The goal of the research described here is to examine the relationship between swipe material
composition and its ability to adsorb explosive molecules as well as to collect explosive particles. The
adsorption experiments were performed by exposure of polymeric membranes with different level of
hydrophobic nature to vapor of different explosives. Following the exposure, the adsorbed explosive was
extracted by a suitable solvent and its concentration was measured using HPLC. To examine collection
efficiency of explosive particles, 100 uL of explosive solution were placed on various substrates and the
solvent was evaporated. The swipe experiments, using as swipe materials the membranes described
above, was carried out using constant force. In this case too, the amount of explosive collected during the
swipe was determined by solvent extraction and the use of an HPLC. The preliminary results of these
experiments are described.
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