Preconcentration of vapors of low-volatile explosives for ion mobility spectrometry

The issue of civil security and prevention of terrorist attacks in public places is becoming more and more actual every year. In this regard, increased attention is paid to detection of explosives. Of particular interest are methods to detect trinitrotoluene (TNT), hexogen (RDX), penthrite (PETN), octogen (HMX). Recently, gas-analytical, nuclear-physical, electromagnetic, terahertz, and biological detection methods have been developed. The lowest detection limit was achieved using gas-analytical methods, namely the non-linear ion mobility spectrometry method, with a limit of detection of 5.10-15 g/cm(3). However, the question of feasibility of using these methods in real conditions is increasingly raised. There is an opinion that it is much more effective to detect explosives by traces than by vapor. In this work we investigated the possibility of detecting vapors of pure explosives with low saturated pressure of vapors. By the example of pure and fa.tory hexogen, using the method of thermal-programmed desorption and mass spectrometry, it was shown that it is hexogen vapor, and not technological impurities or additives with saturated vapor pressure exceeding the saturated vapor pressure of hexogen, that are registered in the gas phase by ion mobility spectrometry. A technique was developed and proposed to concentrate RDX vapors. Using temperature-programmed desorption, the minimal time of concentration and surface fill factor were determined.