Forensic Analysis of Inorganic Anions from Post–Blast Pyrotechnic Residues

Abstract

Increase bombing activities in recent years have raised much awareness amongst forensic scientists of the importance of post–blast investigation. Analysis of post blast bomb residues is useful in identification of explosives and establishing link to its origin. The use of pyrotechnic in homemade explosives has emerged as a new threat to society. In this study, pre and post–blast inorganic anions from pyrotechnic residues were analyzed using ion chromatography with conductivity detection. Inorganic anions were separated using Metrosep A SUPP 5 anion column with NaHCO₃ – Na2CO₃ eluent. Eight anions (fluoride, chloride, nitrite, chlorate, nitrate, phosphate, sulfate and thiocyanate) were successfully separated within 40 min. Good linearity of calibration graph and LOD ranged from 4.8 to 21.0 ppb were achieved. Chemical anionic constituents of the fireworks were found to differ from each other. However, they were found to be common in nitrate and chlorate as oxidizer. Ratio of oxidizer was also found to be much higher than other anions. Post–blast samples showed drastic reduction in oxidizer concentration.