The Identification of Traces of Explosives by Field Spot Tests

The detection and identification of traces of explosives by means of colorimetric spot tests performed upon an adhesive tape substrate have been examined. The adhesive tape serves as a very effective means of collecting a sample, either from suspect material, a working surface, or from the skin of a suspect. Nineteen explosives were examined, these being chosen as representative of military, commercial and amateur explosives. Nineteen different tests were examined, and with the exception of ammonium perchlorate all the explosives considered were found to give a positive response to some, but not all tests. A scheme of analysis was devised that would separate all the candidate explosives. While the investigation has greatly increased the number of spot tests known to be suitable for colorimetric reactions on an adhesive tape substrate, consideration has shown that a multiplicity of tests is not necessarily suitable for use by non-scientists for field testing. Limited, but adequate identification of most explosives may be obtained using only two of the tests. In the course of the investigation a new colorimetric test for RDX and HMX was discovered, and one for perchlorates; in addition, the suitability of an existing test for cyanides for the detection of nitroaromatics was exploited.