Pyrotechnic Residues Analysis – Detection and Analysis of Characteristic Particles by Sem-eds

Many of the improvised explosive devices received at the Forensic Explosives Laboratory (FEL) contain pyrotechnic or home-made explosive mixtures as the explosive charge. Pyrotechnic residues contain a complex mixture of combustion products and unconsumed material. It has been reported that pyrotechnic residues comprise characteristic particles, similar to the formation of gunshot residue particles. In this study a number of pyrotechnic compositions were initiated, both confined and unconfined, and the residues analysed by scanning electron microscopy with energy dispersive spectroscopy for characteristic particles. Spheroid particles were observed in residues from both the unconfined and confined burning studies. Residues from the unconfined burning studies of flash powders and coloured fire comprised spheroid particles with an elemental composition characteristic of the original material, as did residues from the confined burning of the coloured fire compositions. Confined burning of the flash powders yielded residues whose spheroid particles were mainly comprised of elements from the metal fuel plus iron from the steel confinement pipe.