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Analysis of Explosives (LC-MS/MS (BEST TECHNIQUE, At room temp- there is…
Analysis of Explosives
Organic Chemical Extractions
Organic explosives best extracted in
acetonitrile
Resins from pyrotechnic devices in
isopropanol
Fuel oils (in ANFO) and waxes in plastic explosive in
hexane
TLC
Spotted onto a plate w/ known standards and placed in a tank.
Visualised using UV light, then sprayed with
Griess Reagent
to visualise- appear pink
Rf values obtained are comparable w/ known standards
Not confirmatory- further testing required
GC
Some explosives may not be volatile- need to use controlled temp
Adsorption of highly polar explosives- affect elution
High temps- decomposition of thermally liable explosives e.g. nitramines and nitrate esters (must be derivitised)
GC Thermal Energy Analyzer
Analysing compounds containing N-NO or NO2 groups
conc of NO is proportional to the nitro compound
GC compounds are eluted into a pyrolyzer which emits light
GC-TEA
Is a detector which ONLY on pyrolysis compounds give rise to NO
and species that interact with ozone
TEA detector- for
nitroaromatic, nitrate ester and nitramine explosives
GC-MS
Characteristic chromatograms of different explosives
structural elucidation technique used for identification
LC-MS/MS
BEST TECHNIQUE
At room temp- there is not decomposition of thermally liable explosives
Tandem MS - has a collision cell (where a collision gas is introduced)
Ionised by a soft ionisation electro spray ionisation (ESI)
Produces both a parent ion (for structural elucidation) and then subsequent daughter ions- fingerprint
Inorganic Chemical Extractions
Oxidising agents and inorganic post-explosion residues extracted in
DI Water
Surfaces are rinsed- collected- filtered- instrimental analysis
Sulphur, stabilisers & plasticisers best extracted in
chloroform
Metals in
10% HCl solution
Inorganic Ion Chromatography
Separation and detection of ions such as Cl-, NO2-,NO3-, SO42-, ClO3-, ClO4-, Na+, K+, NH4+ & Ca2+
Separates ion by charge
Done at room temp
ICP-AES
Presence of
metals
(metal cations in oxidising agents and fuels) ,
phosphorus
and
sulphur
in explosive mixtures .
Each spectral line are
characteristic
of the elements in the sample.
Intensity is proportional to conc