Definition of major terms ( forensic terrorism, explosives and explosion). History of explosives. Classifications of explosives. Chemical structures of some explosives. Forensic analysis of explosives. Case study.

1. FORENSIC TERRORISM:
DETECTION OF
EXPLOSIVES
MOSES JEDIDAH O. (B.SC.)
(170000140)
BCH 819
COVENANT UNIVERSITY

2. Outline
 Definition of major terms ( forensic terrorism, explosives and explosion).
 History of explosives.
 Classifications of explosives.
 Chemical structures of some explosives.
 Forensic analysis of explosives.
 Case study.

3. Definition of terms
 Forensic terrorism is the application of forensic science in analyzing incidents
of terrorism.
 An explosion is an event that generates a pressure wave as a result of a
sudden increase in volume. It involves burning and detonations. It transcends
just chemical explosion but steam explosion (Bell, 2013).
 An explosive generates the increase in volume by production of gas, through
a chemical reaction or a nuclear reaction (Bell, 2013).

4. History of explosives
 Gun powder was first invented in china about 850AD.
 It was used for fireworks by the Chinese and later used by Europeans as a
weapon of war.
 Gun powder was used exclusively for about 500 years.
 In 1856, Italian chemist, Ascanio Sobero invented the first modern explosive,
nitroglycerin.
 In 1859, Swedish inventor, Alfred Nobel invented the dynamite.
• Dynamite- safe package of nitroglycerin (nitroglycerin + kieselguhr)

5. Classifications of explosives (1 of 3)
 The United States department of transportation classifies explosives into three
categories, for determination of safe shipping (Bell, 2013).
• Class A: Detonation hazard/ maximum hazard. Examples include nitroglycerin and lead
azide.
• Class B: Flammable hazard. Examples include many propellants and pyrotechnic powders.
• Class C: contain A and B explosives as part of the formulation, but in small quantities.

6. Classifications of explosives (2 of 3)
 Classification based on chemical structure and function.
• Nitric compounds (TNT).
• Aromatic nitramines (Tetryl).
• Nitrate esters (Nitroglycerin).
• Peroxides (TATP).
• Initiating explosives (Lead Styphnate).
• Salt formulation (Urea nitrate).
• Fuel/Oxidant formulation (Ammonium fuel oil, or ANFO).

7. Classifications of explosives (3 of 3)
 Classification by forensic analysts (Bell, 2013).
Explosives
High explosives
Primary explosives
Lead styphanate,
mercury fulminate etc.
Secondary explosives
Military
TNT, RDX, HMX, PETN
Industrial
ANFO, dynamite
Propellants
Fig 1: A schematic diagram showing the classification of explosives

8. Primary high explosives
 Primary explosives are more sensitive than secondary explosives.
 They easily detonate by sparks, shock, mechanical force and flames.
 They are often used to detonate secondary high explosives.
Fig 2: Mercury fulminate
Source:https://commons.wikimedia.org/wiki/File:Mercury-
fulminate.png
Fig 3 : Lead styphnate
source:https://commons.wikimedia.org/wiki/File:Bleistyphnat.png

9. Secondary high explosives
 Secondary high explosives are relatively insensitive.
 They detonate when initiated by a primary high explosive.
 They can be mixed with oil or wax to become like clay (plastic explosives).
 They can be pressed flat to fit into an envelope (letter bomb).
Fig 4: Trinitrotoluene (TNT)
Source: https://sv.wikipedia.org/wiki/Fil:Trinitrotoluene.png
Fig 5: pentaerythritol tetranitrate (PETN)
Source: https://commons.wikimedia.org/wiki/File:PETN-semistructural-formula-2D.png
Fig 6: Three stick dynamite
Source: https://en.wikipedia.org/wiki/Explosive_device
Fig 7: Nitroglycerin
Source: https://commons.wikimedia.org/wiki/File:Nitroglycerin.svg

10. Low explosives
 Characterized by the fact that they burn only at their surface.
 Slow combustion is preferred in guns and artillery because rapid explosion
could cause the weapon to blow up.
 Examples of a low explosive are fireworks, black powder, smokeless powder
etc.
Fig 8: 2013 bastille day fireworks over Paris, Francis.
Source: https://en.wikipedia.org/wiki/Fireworks

11. How can explosives be detected?
 Field screening methods.
• Immunoassay and biosensors.
• Ion mobility spectrometry.
 Laboratory methods.
• Spectroscopy (IR and Raman)
• Chromatography
• Mass spectrometry

12. Immunoassay and Biosensor
 Immunoassay is biochemical test based on antibody/antigen interaction for qualitative and
quantitative analysis.
 Biosensors are devices that sense a binding event with high specificity and selectivity.
Fig 9: a scheme showing how the immunoassay works

13. Ion mobility spectrometry
 Ion-mobility spectrometry (IMS) is an analytical technique used to separate and identify
ionized molecules in the gas phase based on their mobility in a carrier buffer gas. (Wikipedia)
 It is used to sense vapors in a stand-off mode or as a direct sensor through thermal
desorption of wipes.
 Most explosive detection work is conducted in the negative ion mode, in which nitrate and
nitrite groups are targeted.
 When a sample is introduced into IMS, a soft ionization occurs via interactions with beta
particles emitted by a 63Ni source.
 Molecules in air form clusters of ions or molecules, and in the negative-ion mode.
 Recently, IMS has been coupled to an electrospray ionization source (ESI) with promising
results for homemade explosives.
 IMS has been successfully used to detect peroxide based-explosives.

14. Ion mobility spectrometry
Fig 10: Schematic diagram of a typical ion mobility spectrometry
Source: https://www.smithsdetection.com/index.php?option=com_k2&view=item&layout=item&id=40&Itemid=638

15. Raman spectroscopy
 Raman spectroscopy is a spectroscopic technique used to observe vibrational, rotational,
and other low-frequency modes in a system (Wikipedia).
 It is commonly used in chemistry to provide a structural fingerprint by which molecules can
be identified.
 It is used for direct and stand-off detection purposes.
 It has the ability to probe through many types of containers.
Fig 11: a schematic diagram describing the principle of the Raman Spectrometry
Source: www.analytical-science.de

16. Infrared spectroscopy
 Fourier transform infrared (FTIR) spectroscopy is a measurement technique
that allows one to record infrared spectra. Infrared light is guided through
an interferometer and then through the sample (or vice versa). A moving
mirror inside the apparatus alters the distribution of infrared light that passes
through the interferometer. The signal directly recorded, called an
"interferogram", represents light output as a function of mirror position
(Wikipedia)
 It can be used to detect pure explosives and aqueous solutions.
 It can also be used to detect reaction products after explosions e.g.
carbonates, thiocynates.

17. Headspace Gas chromatography/ mass
spectrometry (HS-GC/MS)
 Volatile compounds are separated according to their partitioning behavior between mobile
gas and stationary phase in the column.
 Identification of the analyte happens at the mass spectrometer detector.
Fig 12: digram showing the principle of the HS-GC/MS
Source: www.analytical-science.de

18. Other examples of detection
technologies

19. A case study in forensic chemistry: The Bali
bombings (Royds, et al., 2005)
 the bombing occurred in Bali on the 12th of October 2002.
 It occurred around 11pm.
 Two other bombs were detonated after the first bomb.
 People had different stories to the explosion
• Gas cylinder explosion

20. Things found in the scene
 Structural damages, burning motor, vehicles and buildings.
 Tiny fragments of tartan fabrics.
 Connective tissues and spatter marks were visible on the ceiling above the epicenter.
 A dismembered head and two lower legs.
 Foot print in an aluminum dust on a black gelatin life.
 Barely visible footprint on the surface of a newspaper.

21. The Bali bombing
Fig 13: Water filled crater outside the Sari Club
(Royd et al, 2005).
Fig 14: the newspaper with a barely visible footprint
on its surface (Royd et al, 2005).
Fig 15: the footprint in aluminum dust on a black gelatin life
(Royd et al, 2005).

22. Actions carried out to detect explosives
used
 Investigative and forensic officers were deployed to the scene immediately.
 A nearby motel room was cleared and prepared for the installation of some instruments :
• Microscope
• Camera
• Ion mobility spectrometer (IMS)
• Portable infra-red spectrometer (FT-IR)
• Reagents
• Spot tests.
 The rationale behind a mobile laboratory was to produce tentative findings for the
investigators whilst reducing the number and volume of samples to be sent to the main
laboratory for more exhaustive confirmatory analyses.
 Samples from the scene were also taken to a comprehensive chemical laboratory to carry out
further analysis

23. Results after series of investigations
 At the end of the series of investigations:
• It was identified that a the bomb was detonated by a suicide bomber.
• The location of the production of the explosive was discovered.
• The major component of the bomb (trinitrotoluene) was discovered.
• By the use of DNA fingerprinting the culprits were discovered and the result was used to trace their
source.
• As a result of the forensic investigation, a major explosion was also averted.

24. Conclusion
Explosives are extreme examples of combustion in which hot gases and
pressure are exploited for damage. Several analytical methods have been
employed in the detection of these explosives. More technologies are been
developed to better analyze these explosives.

25. References
 Bell, S. (2013). Forensic Chemistry. Second edition. Pearson Education Inc.
ISBN 978-0-321-81687-0.
 www.analytical-science.de
 Royds, D., Lewis, S. W. and Taylor, A. M. (2005). A case study in forensic
chemistry: the Bali bombing. Talanta 67: 262-268.
 en.wikipedia.org