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The Effect of Laser Power Density on the Observed Products of Combustion of Gasoline Using Laser-Induced Thermal Desorption with Fourier Transform Mass Spectrometry


  • Supported by the Jan Bashinski Grant from the Forensic Sciences Foundation.
  • Presented in part at the 62nd Annual Meeting of the American Academy of Forensic Sciences, February 22-27, 2010, in Seattle, WA.

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Donald P. Land, Ph.D.

University of California

Department of Chemistry

One Shields Avenue

Davis, CA 95616



Layered soot analysis is explored as a potential indicator of gasoline in a fire. Current techniques lack the ability to analyze layered soot samples without the destruction of the layered information. Laser-induced thermal desorption (LITD) coupled with Fourier transform mass spectrometry (FTMS) is developed as a method for analyzing soot samples. Samples of soot on glass from the free combustion of gasoline are collected and analyzed using LITD-FTMS, and the effect of power density on the resulting chemical profile is reported. At higher power densities, a distribution of low m/z products is observed. At lower power densities, the products observed shift to higher molecular weights, with peaks attributable to the tropyllium ion, naphthalene, and pyrene. Results at low power densities suggest that LITD-FTMS is a viable method for the analysis of soot, with potential for use with layered soot samples. Peaks potentially useful for fuel differentiation of gasoline are identified.