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Polycyclic Aromatic Hydrocarbons In Gasoline and Their Applications to Arson Investigations By Kathleen Barbosa.

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Presentation on theme: "Polycyclic Aromatic Hydrocarbons In Gasoline and Their Applications to Arson Investigations By Kathleen Barbosa."— Presentation transcript:

1 Polycyclic Aromatic Hydrocarbons In Gasoline and Their Applications to Arson Investigations By Kathleen Barbosa

2 Forensic Chemistry Arson Investigations Components of ignition and combustion reaction – Fuel – Oxidizing Agent – Heat – Uninhibited Chemical Chain Reaction Identify Ignitable Liquid Residues (IRLs) – Fire Accelerant vs IRLs

3 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

4 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

5 PAHs in Gasoline 19 compounds Most abundant – Naphthalene – 2-Methylnaphthalene – 1-Methylnaphthalene – Biphenyl – Acenaphthylene

6 PAHs (or lack there of) in Diesel Higher number of alkenes Pattern differences – Petrol refineries/oil Abundance of compounds – Dodecane – Tridecane – 2-Methylnaphthalene – Tetradecane

7 GC-MS Data GasolineDiesel

8 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

9 Written Component Crime Prevention Pamphlet Hot On Your Heels! How Forensic Chemistry Helps Convict Arsonists

10 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: Academic Search Complete, 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) 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), doi: /AL 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), doi: /fam.2132

11 BURNING QUESTIONS?


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