Jehuda Yinon

Field detection and monitoring of explosives

Detection of explosives in situ is of major importance in several applications: finding hidden explosives in airport luggage and in mail; screening of personnel for concealed explosives; environmental monitoring of explosives-contaminated sites; and, detection of buried landmines. Mobile and hand-held detectors have been developed for the various applications. They can be sub-divided into three classes: vapor and particle detectors; radiation detectors; and, biochemical detectors. An overview of the various explosives detectors and their principles of operation is presented.

Identification of nitrate ester explosives by liquid chromatography-electrospray ionization and atmospheric pressure chemical ionization mass spectrometry.

Liquid chromatography-mass spectrometry (LC-MS) with electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI), in the negative-ion mode, was investigated for the analyses of three widely used nitrate ester explosives, pentaerythritol tetranitrate, nitroglycerin and ethylene glycol dinitrate, as well as six additional nitrate esters, using post-column additives. In ESI, ammonium nitrate, sodium nitrite, propionic acid and ammonium chloride promoted formation of characteristic adduct ions of the respective nitrate esters. In APCI, chlorinated agents, dichloromethane, chloroform, carbon tetrachloride and ammonium chloride, were employed, fanning chloride attachment adduct ions. Three forensic samples, Booster DYNO, Semtex and Smokeless Powder, were analyzed to demonstrate the validity of the developed LC-MS methods.

Characterization and origin identification of 2,4,6-trinitrotoluene through its by-product isomers by liquid chromatography-atmospheric pressure chemical ionization mass spectrometry

The by-products of industrial 2,4,6-trinitrotoluene (TNT), including isomers of trinitrotoluene, dinitrotoluene, trinitrobenzene and dinitrobenzene were investigated using liquid chromatography-mass spectrometry (LC-MS), in order to build a profile for the characterization of TNT samples from various origins. LC-MS with atmospheric pressure chemical ionization, in the negative-ion mode, was found to be the most suitable method for this study. The characterization of TNT by the by-product profile was demonstrated on a variety of TNT samples.

Analysis of Explosives

I. INTRODUCTION The analysis of explosives is of major importance in several analytical fields: 1. Forensic identification of explosives is a major problem in the criminalistic investigation of a bombing which involves connecting the type of explosive used with the suspect. The detection and identification of explosive residues in debris material constitutes a highly difficult task. The thermal instability of most explosives, along with the requirements of high sensitivity of the analysis, limit the number of analytical techniques which can be used in such determinations. 2. The detection of explosives concealed in airline baggage or in mail is an extremely relevant analytical problem which requires a highly sensitive as well as a specific method for its solution. Highly specific monitors are expected to identify and detect the presence of molecules of explosive material in the sampled air environment in the suspected baggage or mail. 3. The accurate determination of the composition of explosives is very ...

Forensic identification of dyes extracted from textile fibers by liquid chromatography mass spectrometry (LC-MS)

LC-MS is used for the identification of dyes extracted from textile fibers and the utility of the method for forensic trace analysis is demonstrated. The technique is shown to provide a high degree of chemical structural information, making dye identification highly specific in comparison to optical and/or chromatographic methods of dye analysis. A UV-visible absorbance detector, placed in series before the MS detector, facilitates monitoring the elution of dyes in the presence of other non-dye components extracted from colored textile fibers. In this way, dye identification becomes practical, even when a dye standard is not available for comparison. A set of 22 reference dyestuffs and 10 dyes extracted from textile fibers were analyzed to demonstrate the utility of the method. Six of the extracted dyes corresponded to dyes also contained in the set of 22 reference dyestuffs. Reference dyestuffs were not available for four of the extracted dyes. Triethylamine (TEA) was shown to increase the electrospray ionization-mass spectrometry (ESI-MS) response of dyes containing multiple sulfonated groups.

Tracking the Terrorists: Identification of Explosive Residues in Post-Explosion Debris by LC/MS Methods

In order to identify the type and origin of explosives in post-explosion debris, several groups of explosives, including TNT, RDX, nitroglycerin, PETN, EGDN, ammonium nitrate and some other inorganic oxidizers, were studied using LC/MS with electrospray and APCI ionization, and MS/MS for further confirmation of identified ions.

Summary of the Workshop

Eighteen papers and two posters were presented by scientists from eight different countries during the two days of the NATO ARW.