Development of an explosive information system for the chemical composition profile of explosives

Abstract

Analysis of post-blast residues collected from a crime scene is of great importance to forensic investigators in determining the nature of explosives used. The result of the analysis can be used as ultimate evidence in court to link a suspect with the crime. The traditional manual matching of explosive sample for case and control samples are often laborious and inefficient. The scarcity of standard explosives further aggravates the routine work of a forensic analyst. This study was therefore undertaken to develop a novel forensic explosive database information system for rapid and efficient data retrieval and matching. A total of 22 pre- and post-blast samples were collected including military explosives, improvised explosive devices and pyrotechnic explosive samples. All samples were subjected to spot test analysis prior to instrumental analysis. High performance liquid chromatography with diode array detector (HPLC-DAD) and gas chromatography tandem mass spectrometry (GC-MS/MS) were used for chemical profiling of high explosives with limits of detection (LOD) in the range of 0.02-4.35 mg/L and 0.30-10.89 ng/L, respectively. Ion chromatography (IC) was employed for chemical profiling of anionic (LOD: 0.07-0.26 mg/L) and cationic (LOD: 0.08-0.28 mg/L) content of inorganic low explosives. This study revealed that each sample displayed different chromatographic profile that could discriminate from one to another. Nitroexplosive compounds of PETN and tetryl were detected in GC-MS/MS analysis via the presence of degradation products of 1,3-propanediol,2,2-dimethyl-,dinitrate and 2,4,6-trinitro-N-methyl-aniline, respectively. Methods developed for IC, HPLC and GC-MS/MS were proposed as standard methods for the generation of results to be incorporated in the explosive database. A total of 52 data information was stored in the database using Microsoft SQL Server. MyForensic Explosive Database (MyFED) graphical user interface was developed using Microsoft Visual Studio. The database incorporated details of the explosives, results of spot test analysis, retention factor and chromatographic profile of each analyte for data searching, retrieval and matching with unknown explosive samples. The user interface involved spot test analysis comparison, followed by chromatogram searching with retention factor comparison. The administrator page allowed access only to the administrator for viewing, inserting, editing and deleting information. The developed MyFED information system supported easy matching of unknown explosive samples with known samples stored in the database. Although the database contained a limited number of explosives data, its capability of easily upgradable to handle more explosive information renders MyFED an attractive and promising start of a Malaysian database system available for use to forensic investigators in Malaysia as well as in the Asian region.