05-02-2013, 02:31 PM
HEADSPACE ADSORPTION
[attachment=49705]
The flammable liquid vapour is adsorbed onto a suitable medium such as charcoal.
It require sample to be heated may be passive or dynamic
It is very sensitive method,simpler and more rapid than steam and vapour distillation.
It generally favour recovery of bioling point hydrocarbon components.
Solvent extraction
Applied to small samples of fire debris and require the sample to be immersed in a suitable volatile solvent its demerits is it can’t extract many pyrolysis product ,dyes and oter chemical .
Can be used for both solid and liquid.
Clean-up
Refer to the process of cleaning a sample or extract to prepare it for analysis.
Filtration:- used to remove suspended solids from a neat liquid sample
Acid stripping:- used to remove oxygenated or nitrogenated compound that arise from a combustion of synthetic material
These compounds interfere with the analysis of flammable and combustile liquid
Addition of small quantity of mineral acid,extraction is possible.
Gas chromatography
It is a method used to seperates components of mixture of volatile compounds.
Normally, the seperation are made to identify or quantitise the constituents in a sample mixture but in some application the seperation are made for preparatives purposes.
Insturementation
A carrier which is maintain at high pressure.
A sample injector system.
A seperator coloumn .
one or more detectors.
An amplification and recorder system.
Gas chromatografy/mass spectrometry(GC/MS)
GC/MS uses the same components seperation process as GC .
In the case of single components products, this may be regarded as a positive identification.
MS is an effective method to determine the molecular weight and structure compound
It is advantagenous to other method of analysis in its ability to separate and analyse mixture of compounds.
It is sensitive tecnique with current level of accuracy within the range of one mass unit.
Microscopy/scanning electron microscopy
Applied in analysis of debris and fire scenes.
An unidentified object and unknown material can be identified by examination using a low power microscope.
May permit recognition of components of incendiary devices, of details of paper or material used as fuel, physical match of evidence found at scene or suspect house.
[attachment=49705]
The flammable liquid vapour is adsorbed onto a suitable medium such as charcoal.
It require sample to be heated may be passive or dynamic
It is very sensitive method,simpler and more rapid than steam and vapour distillation.
It generally favour recovery of bioling point hydrocarbon components.
Solvent extraction
Applied to small samples of fire debris and require the sample to be immersed in a suitable volatile solvent its demerits is it can’t extract many pyrolysis product ,dyes and oter chemical .
Can be used for both solid and liquid.
Clean-up
Refer to the process of cleaning a sample or extract to prepare it for analysis.
Filtration:- used to remove suspended solids from a neat liquid sample
Acid stripping:- used to remove oxygenated or nitrogenated compound that arise from a combustion of synthetic material
These compounds interfere with the analysis of flammable and combustile liquid
Addition of small quantity of mineral acid,extraction is possible.
Gas chromatography
It is a method used to seperates components of mixture of volatile compounds.
Normally, the seperation are made to identify or quantitise the constituents in a sample mixture but in some application the seperation are made for preparatives purposes.
Insturementation
A carrier which is maintain at high pressure.
A sample injector system.
A seperator coloumn .
one or more detectors.
An amplification and recorder system.
Gas chromatografy/mass spectrometry(GC/MS)
GC/MS uses the same components seperation process as GC .
In the case of single components products, this may be regarded as a positive identification.
MS is an effective method to determine the molecular weight and structure compound
It is advantagenous to other method of analysis in its ability to separate and analyse mixture of compounds.
It is sensitive tecnique with current level of accuracy within the range of one mass unit.
Microscopy/scanning electron microscopy
Applied in analysis of debris and fire scenes.
An unidentified object and unknown material can be identified by examination using a low power microscope.
May permit recognition of components of incendiary devices, of details of paper or material used as fuel, physical match of evidence found at scene or suspect house.