LC-MS/MS
Definition
Liquid chromatography coupled to tandem mass spectrometry. The preferred confirmatory method for non-volatile organic explosives (PETN, RDX, TNT, NG) because it avoids thermal decomposition at GC injector temperatures and achieves picogram sensitivity with high selectivity.
- Full name
- Liquid chromatography tandem mass spectrometry
- Targets
- PETN, RDX, TNT, nitroglycerin
- Advantage over GC
- Avoids thermal decomposition
- Sensitivity
- Picogram-level detection
Common questions
Why can't GC-MS reliably confirm PETN or nitroglycerin?+
These explosives can decompose at the high injector temperatures a gas chromatograph uses to vaporise a sample, producing breakdown products instead of the intact molecule. LC-MS/MS separates and ionises the compound without heating it, preserving it for accurate identification.
What does 'tandem' mean in LC-MS/MS?+
It means two stages of mass analysis are linked: the first isolates an ion of a specific mass, which is then fragmented and the resulting fragment masses are measured. Matching both the parent and fragment masses gives much higher confidence than a single mass measurement alone.
Related terms
- ASTM E2998
- Standard Guide for Sampling Improvised Explosive Devices and Post-Blast Debris for Explosive Residue Analysis. Specifies cotton swabs, isopropanol or methanol pre-wetting, swabbing...
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- Friction Lid
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- Ion Mobility Spectrometry (IMS)
- A field-deployable analytical technique that separates ions by their mobility in an electric field at atmospheric pressure. Used for trace explosive detection...
- Mahazar
- The formal seizure list used in Indian criminal procedure (BNSS 2023) to document the collection of physical evidence at a scene. Prepared...
- Passive Headspace Concentration (PHC)
- ASTM E1412 extraction method. The sealed evidence container is heated at 60-80°C; volatilised hydrocarbons adsorb onto an activated charcoal strip suspended in...
- Selected Ion Monitoring (SIM)
- A GC-MS operating mode in which the mass spectrometer monitors only a set of pre-selected diagnostic m/z values, rather than scanning the...
- Tamper-Evident Sticker
- A self-adhesive label applied across the lid-rim or closure interface of an evidence container. Any disturbance of the container after sealing leaves...
- Unlined Metal Can
- The standard evidence container for fire debris analysis. 'Unlined' refers to the absence of internal plastic or epoxy coating, which would contribute...