18 Questions
What is the purpose of comparing the chromatographic pattern of an unknown sample to known petroleum products?
Identifying the source of the unknown sample
Where can a forensic analyst find a searchable library to compare the chromatograms of accelerant standards?
ILRC website
What technique can simplify complex chromatographic patterns in forensic analysis?
Gas chromatography/mass spectrometry
What is the characteristic nature of explosives that distinguishes them from other substances?
Rapid oxidation reaction
Which of the following is an example of a low explosive used widely?
Black powder
What is the term for the speed of decomposition exhibited by low explosives confined to containers?
Deflagration
What is the purpose of placing a charcoal strip in the airtight debris container during heating?
To absorb much of the vapors for recovery of accelerant residues.
How are the volatile residues in fire-scene debris trapped during the laboratory recovery process?
By heating the airtight container and capturing the vapor in its airspace.
Why is a syringe used after heating the container during laboratory recovery of flammable residues?
To remove the trap vapor for injection into a gas chromatograph.
What role does the solvent play in the vapor concentration technique?
Recovering accelerant vapors absorbed by a charcoal strip.
Why is gas chromatography considered a sensitive and reliable instrument for detecting and characterizing flammable residues?
It separates hydrocarbon components and produces characteristic chromatographic patterns.
How can a forensic analyst identify the accelerant used in an arson case using gas chromatography?
By comparing gas chromatographic peaks from fire-scene debris to known flammable liquids.
What is the purpose of using the ion mobility spectrometer mentioned in the text?
Identifying explosive residues in materials collected for laboratory examination
Why is it essential to collect and preserve loose soil and debris from the interior of a crater at the origin of an explosion?
To analyze the debris by gas chromatography/mass spectrometry
What is the purpose of rinsing recovered debris with organic solvents in forensic analysis?
To identify accelerants used in the explosion
Why is it important to use sealed air-tight containers for materials collected for laboratory examination?
To prevent contamination of nearby containers by diffusing explosives
What type of testing procedure is NOT mentioned as part of the analysis conducted on recovered debris?
Vapor concentration technique
Why are confirmatory identification tests performed on unexploded materials?
To confirm the presence of explosives in the unexploded materials
Learn about the procedure for recovering accelerant residues from fire-scene debris in a laboratory setting. Understand how volatile residues are driven off, trapped, and analyzed using gas chromatography.
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