Ion Chromatography (IC)
Definition
An analytical technique that separates and quantifies anions and cations in solution. In post-blast residue analysis, IC detects nitrate, nitrite, ammonium, and chlorate ions that are characteristic of specific explosive formulations, particularly ANFO and potassium chlorate mixtures.
- Primary use in forensics
- Detects inorganic ionic residues in post-blast debris
- Key ions detected
- Nitrate, nitrite, ammonium, chlorate, perchlorate, carbonate, sulfide
- Best for
- ANFO devices, black powder, chlorate mixes, urea nitrate formulations
Common questions
What does ion chromatography actually detect in bomb debris?+
IC separates and identifies specific ions left behind by explosives, like nitrate, ammonium, nitrite, chlorate, and perchlorate. These ionic signatures are telltale markers of which explosive type was used, whether ANFO, black powder, urea nitrate, or chlorate-based mixes.
Why is ion chromatography the preferred method for ANFO residues?+
ANFO contains ammonium ions and nitrate ions that need to be separated from each other and detected precisely. IC with suppressed conductivity detection is the only practical instrument that can reliably identify and measure these specific ions together.
Can other techniques replace ion chromatography for post-blast analysis?+
For inorganic ionic residues like nitrate and perchlorate, IC is the primary analytical technique. Other methods can detect organic explosives, but when the explosive is black powder or AN-based, IC is the go-to choice because it targets the exact ions these devices leave behind.
Related terms
- ANFO
- Ammonium nitrate fuel oil: 94% ammonium nitrate prills + 6% diesel fuel oil. Detonation velocity approximately 4,500-4,800 m/s. The most widely used...
- ANFO (Ammonium Nitrate Fuel Oil)
- A low-sensitivity bulk explosive mixture of prilled ammonium nitrate (94 per cent by weight) and fuel oil (6 per cent). The primary...
- Blast Seat
- The origin point of an explosion, characterised by a crater (in contact detonations), radiating damage patterns, and the highest concentration of explosive...
- Brisance
- The shattering power of a detonating explosive, distinct from heave (bulk displacement). Measured by the Trauzl lead block test. High-brisance explosives (RDX,...
- Commercial Pyrotechnic Powder
- Low explosives (black powder and flash powder) extracted from commercially available fireworks. Used in the Boston Marathon bombing devices. Not subject to...
- Daubert Standard
- The US federal evidentiary standard (Daubert v. Merrell Dow Pharmaceuticals, 1993) requiring that expert testimony be based on scientifically valid methods with...
- Deflagration
- A subsonic combustion front propagating through an explosive by thermal conduction. Characteristic of low explosives such as black powder and smokeless powder;...
- Deflagration-to-Detonation Transition (DDT)
- The acceleration of a deflagrating burn front to supersonic detonation velocity, triggered by confinement. Relevant to understanding how improvised devices using low...
- Detonation
- A supersonic shock wave coupled to a chemical reaction front, propagating through a high explosive at velocities between approximately 4,500 and 9,100...
- Diphenylamine Test
- Color test for nitrates and nitro groups. Diphenylamine in conc. H2SO4 turns deep blue with oxidising NO3-/NO2-. Also a primer-residue test, which...
- Forensic Explosives Laboratory (FEL)
- The DSTL-operated laboratory at Fort Halstead, Kent (UK), responsible for explosives identification and device analysis in UK terrorism cases. UKAS-accredited for post-blast...
- GC-TEA
- Gas chromatography with a Thermal Energy Analyser. Pyrolytic cleavage of the nitro group to NO followed by chemiluminescent reaction with ozone. Nitro-specific,...
Explained in these topics
- Explosives Classification: Low, High, Primary, Secondary, TertiaryThe primary analytical technique for detecting inorganic ionic residues (nitrate, nitrite, carbonate, sulfide, chlorate, perchlorate) in post-blast debris, par...
- Forensic Analysis of Explosives and Post-Blast ResiduesAnion / cation separation with suppressed conductivity detection. The only practical instrument for ANFO (NH4+, NO3-), urea nitrate and chlorate / perchlorate...
- Major Bombing Casework: Oklahoma, Mumbai, 7/7, Boston, ManchesterAn analytical technique that separates and quantifies anions and cations in solution. In post-blast residue analysis, IC detects nitrate, nitrite, ammonium, an...