1. Evidence

2. Collection Explosion usually followed by fire
Often destroyed by one or other
Dangerous – shards of glass or metal, toxic or flammable vapors, 2nd explosion
Large crater = point of origin

3. Collect soil and debris from inside crater
Test nearby objects for explosive residue or pieces of detonator
Use sieves to sift for small pieces
Follow chain of custody
Package separately in metal containers – label where found

4. Analysis ID types of explosives & mechanisms of detonation
First – preliminary tests, then confirmatory tests

5. Use stereomicroscopy
- examine debris for unexploded material
- look for certain shapes and colors
- look for pieces of wrapper from dynamite, metal from pipe, pieces of wire

6. Chemical Analysis Wash debris w/ acetone to dissolve explosives
Color Spot Test – screens for various explosives
Mix small amount of conc. acetone & explosive solution with a specific reagent – observe

7. Several tests –
- Modified Griess Test – presence of nitrite (NO2-) (orange)
- Alcoholic Potassium Hydroxide (KOH) – presence of TNT (blue or violet)
- Diephenylamine – most explosive residues (not TNT or RDX) (blue or black)

8. Reactions Explosive Modified Griess Test Alcoholic KOH Diphenylamine
Nitrate
None
Blue to Blue-Black
Nitrocellulose
Nitroglycerine
Trinitrotoluene (TNT)
RDX
PETN

9. Reactions Explosive Modified Griess Test Alcoholic KOH Diphenylamine
Nitrate
None
Blue to Blue-Black
Nitrocellulose
Orange
Blue-Black
Nitroglycerine
Trinitrotoluene (TNT)
RDX
PETN

10. Reactions Explosive Modified Griess Test Alcoholic KOH Diphenylamine
Nitrate
None
Blue to Blue-Black
Nitrocellulose
Orange
Blue-Black
Nitroglycerine
Trinitrotoluene (TNT)
RDX
PETN

11. Reactions Explosive Modified Griess Test Alcoholic KOH Diphenylamine
Nitrate
None
Blue to Blue-Black
Nitrocellulose
Orange
Blue-Black
Nitroglycerine
Trinitrotoluene (TNT)
Red to Violet
RDX
PETN

12. Reactions Explosive Modified Griess Test Alcoholic KOH Diphenylamine
Nitrate
None
Blue to Blue-Black
Nitrocellulose
Orange
Blue-Black
Nitroglycerine
Trinitrotoluene (TNT)
Red to Violet
RDX
PETN

13. Reactions Explosive Modified Griess Test Alcoholic KOH Diphenylamine
Nitrate
None
Blue to Blue-Black
Nitrocellulose
Orange
Blue-Black
Nitroglycerine
Trinitrotoluene (TNT)
Red to Violet
RDX
PETN
Blue

14. Chromatography TLC – Thin Layer Chromatography Calculate Rf values
Use cellulose or silica gel plates as stationary phase
Mixture of unknown explosives rinsed w/ solvent
Compared to knowns
Can also use HPLC

15. Confirmatory Tests After prelim ID
Infrared spectroscopy or Gas chrom – Mass spec – confirm ID of organics (TNT, military explosives)
IR spec – IR light passes thru sample and measures amount of energy it absorbs
GC-MS – GC separates compounds in mixture
MS – compounds broken into smaller charged particles – separated by mass & charge

16. Physical Evidence Clues about perpetrator
Pieces of wire, pipe, detonators – fingerprints, explosive residue on clothes, serial number on watch, tool marks on pipe, torn edges of duct tape