Download Slide 1 - Clayton State University

Polycyclic Aromatic Hydrocarbons In
Gasoline and Their Applications to Arson
Investigations
By Kathleen Barbosa
Forensic Chemistry
• Arson Investigations
• Components of ignition and combustion
reaction
–
–
–
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Fuel
Oxidizing Agent
Heat
Uninhibited Chemical Chain Reaction
• Identify Ignitable Liquid Residues (IRLs)
– Fire Accelerant vs IRLs
Identifying IRLs
• Specific Polycyclic Aromatic Hydrocarbons
(PAHs) in gasoline
– Ability to extract and identify these compounds even when
sample is significantly evaporated
• soot
– 19 specific compounds in gasoline soot
– Ability to differentiate from pyrolysis residues of carrier objects
Laboratory Analysis
• Common methods
– Solid Extraction
• Solids suspended in liquid
– Headspace extraction
• Gas above sample in vial
– Adsorption Extraction
• Many techniques
• GC-MS
• Comparison of known ignitable liquids
– Database
– Must be from same instrument
PAHs in Gasoline
• 19 compounds
• Most abundant
– Naphthalene
– 2-Methylnaphthalene
– 1-Methylnaphthalene
– Biphenyl
– Acenaphthylene
PAHs (or lack there of)
in Diesel
• Higher number of alkenes
• Pattern differences
– Petrol refineries/oil
• Abundance of compounds
– Dodecane
– Tridecane
– 2-Methylnaphthalene
– Tetradecane
GC-MS Data
Gasoline
Diesel
What’s The Point?
• Identification of Arson
– Use of accelerants common
– Pour Patterns
– Localized Burning
• Seized Sample Comparison
• Matching to specific station??
– Class evidence
• The future!
– Hydrocarbon Sniffers
• Trained by chemists!
– Insurance Fraud
Written Component
• Crime Prevention Pamphlet
Hot On Your Heels!
How Forensic Chemistry Helps Convict Arsonists
References
Chih-Ming Huang, et al. "Identification Of Gasoline Soot In Suspect Arson
Cases By Using Headspace Solid Phase Microextraction–GC/MS."
Analytical Letters 37.7: 1373-1384. Academic Search Complete, 2004.
Chordas, L. (2011). No bones about it: State Farm's Arson Dog Program trains
and funds accelerant-detection dogs to sniff out fraud. Best's Review, (7).
104.
Stauffer, E., Dolan, J., Newman, R. (2008). "Extraction of Ignitable Liquid
Residues from Fire Debris". Fire Debris Analysis. Academic Press. pp. 387–
426.
Wu, C., Chen, C., Huang, C., Lee, M., & Huang, C. (2004). Identification of
Gasoline Soot in Suspect Arson Cases by Using Headspace Solid Phase
Microextraction–GC/MS. Analytical Letters, 37(7), 1373-1384.
doi:10.1081/AL-120035904
Zhi, Y., Zong, R., Guangxuan, L., Liu, H., & Jialei, T. (2013). The source
identification and classification study of soot after combustion. Fire &
Materials, 37(3), 246-256. doi:10.1002/fam.2132
BURNING QUESTIONS?