Identification of Accelerants in Fire Residues by Capillary Column Gas Chromatography

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Abstract
Since the early 1960s, gas chromatography has been used as a means of determining the presence of hydrocarbons in fire residues. Early investigators relied on packed columns and thermal conductivity detectors. Their results proved that the hydrocarbons could be detected in fire residue [1]. Later work [2] explored the recovery of many different accelerants from various types of fire residues. The method of Ettling's experiments [2] is questionable, and the equipment lacked the resolving power of capillary columns of the support-coated open-tubular type. The burning conditions and time element were not related to typical arson field investigation conditions. In the conclusions of the 1968 study [2], residues were analyzed by comparing a residue chromatogram to a chromatogram of a blank. The blank was a fire residue from materials not ignited by any accelerant. The chromatographic peaks that appeared on the sample chromatogram but not in the blank were attributed to the accelerant. Accelerants were not detected in several residues that had burned for more than 2 min. This conclusion is not fully supported by the present results. We find that residues from fir are more difficult to identify than those from pine. The heat intensity of burning fir volatilizes more accelerant than is characteristic of burning pine, for example. The present study was designed to expand on previous work, to build a file of representative chromatographs, to explore techniques in hydrocarbon determination, and to develop a rapid means of identifying accelerants in fire residues.