| Popis: |
Central Forensic Science Laboratory, Government of India, 30, Gorachand Road, Kolkata-700 014, India E-mail : bagchiseema@gmail.com, sujitclahiri@yahoo.com Fax : 91-33-22849442 Geological Survey of India, Government of India, Kolkata-700 069, India E-mail : cashu@rediffmail.com Chemical Examination Laboratory, Excise Department, Government of West Bengal, Kolkata-700 046, India E-mail : kuiladk@rediffmail.com More than 1650 pre blast and post blast exhibits were analyzed using routine analytical procedures supplemented by advanced analytical techniques like Ion-Chromatography (IC) (mainly), Scanning Electron Microscope with Energy Dispersive X-ray Analyzer (SEM-EDXA), Fourier Transforms Infrared Spectroscopy (FTIR), Atomic Absorption Spectrometer (AAS) (for a number of samples) for inorganic constituents and High Performance Liquid Chromatography (HPLC), High Performance Thin Layer Chromatography (HPTLC), Gas Chromatograph-Mass Spectrometer (GC-MS), UV-Visible Spectrophotometer, Fourier Transform Infrared Spectroscope (FTIR), Liquid Chromatography-Tandem Mass Spetrometry (LC/MS/MS) for organic constituents. Results of the investigations suggested that high explosives like nitroglycerine, di and tri nitrotoluene (DNT and TNT), tetryl, cyclonite (RDX), pentaerythritol tetranitrate (PETN) were rarely used except in mortars and detonators. Common easily available unrestricted chemicals like potassium nitrate/ chlorate (KNO3/KClO3), arsenic sulphide (As2S3), sulphur, aluminium powder of different mesh size and sodium, calcium, magnesium, barium, strontium (Na+, Ca+, Mg+, Ba+, Sr+) nitrate with varying compositions along with splinters were used. But there were perceptible changes in the modus operandi of the terrorists. There had been a spurt in the use of different types of ammonium nitrate (AN) based explosives like AN, AN+Al, ANFO (ammonium nitrate and fuel oil/ diesel/kerosene), AN+wax, AN based gel/emulsion/slurry explosives with other ingredients. Urea nitrate was also obtained. The article contains a brief description of works on AN+wax, AN based emulsion and uranium nitrate based explosives sent to CFSL and examined in the laboratory of CFSL. Aspects relating to ascertain the trace of the origin of the explosives by determining the ‘isotopic signature’ of the elements (C, N, O, H) in the explosives and biomarker fingerprinting of the petroleum products in the explosives were discussed. Figures relating to the quantitative estimation of the compounds of the explosives and some experimental figures related to the validation of the experimental findings have been incorporated. However, in view of increased terrorist activities and development of new arsenals, it is desirable to make on spot examination of explosive residues using high sensitive explosive detection system (EDS) and explosive trace detection (ETD) techniques. Restriction and proper monitoring of the explosivematerials and the desirability of undertaking counter terrorism or preventive forensic protocols to limit terrorist activities are needed. |
