IMS
Definition
Ion Mobility Spectrometry. Drift-tube separation of gas-phase ions at ambient pressure. Smiths IONSCAN 500DT and Sabre 5000 give 5-second field screening on swabs.
- Full name
- Ion Mobility Spectrometry
- Principle
- Drift-tube separation of gas-phase ions
- Field speed
- About 5 seconds per swab
- Example instruments
- Smiths IONSCAN 500DT, Sabre 5000
Common questions
What causes a false positive in IMS explosive screening?+
Common substances such as certain hand lotions, cleaning agents, or pharmaceuticals can produce ions with similar drift times to target explosives, which is why positive field alerts are typically confirmed by laboratory methods such as GC-MS.
Why is IMS favoured for field checkpoints over laboratory methods?+
Its drift-tube separation works at ambient pressure with no vacuum system, giving results in seconds directly on a swab sample, a speed and portability laboratory GC-MS or LC-MS cannot match.
Related terms
- 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...
- 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,...
- Ion Chromatography (IC)
- An analytical technique that separates and quantifies anions and cations in solution. In post-blast residue analysis, IC detects nitrate, nitrite, ammonium, and...
- Janowski Test
- Color test for nitroaromatics. Sample plus DMSO plus alcoholic KOH gives a violet Meisenheimer complex. Positive for TNT, picric acid, tetryl and...
- Modified Griess Test
- A contact-transfer colour chemistry test for nitrite-containing propellant combustion residue. Sulphanilic acid undergoes diazotisation with nitrous acid (from NO2 on the target...
- Post-Blast Residue (PBR)
- Unconsumed explosive plus reaction by-products left at the seat of an explosion, on debris, on fragments and on the hands or clothing...
- VBIED
- Vehicle-Borne Improvised Explosive Device. Pulwama 2019 is the recent Indian reference case (RDX plus ammonium nitrate).