Variations in Ignitable Liquid Residue Components with Collection and Storage Conditions

gnitable liquid residues are essential evidence in fire investigations, serving as critical clues for determining both arson and accidental fires as well as for interpreting fire causes. However, in practice, the lack of dedicated storage containers, delays in evidence collection, and long-term storage often pose the risk of compound loss. In this study, samples were prepared by combining different flooring materials, storage containers, collection times, and storage durations. The samples were then analyzed using gas chromatography–mass spectrometry to evaluate the residual levels of ignitable liquid compounds. The results showed that glass bottles preserved the major components well, even during long-term storage, whereas most compounds were lost when stored in polyethylene zipper bags. In particular, samples collected three days after a fire incident, instead of immediately, exhibited rapid compound loss under exposure, demonstrating that delayed collection has the greatest impact on preservation. Substrate comparisons further revealed that carpets and wooden flooring exhibited relatively high compound retention owing to their structural characteristics. By contrast, gasoline, diesel, kerosene, and thinners commonly failed to retain detectable ignitable liquid residues when stored for long periods in zipper bags. This study provides scientific evidence for the management of ignitable liquid residues and is expected to support improvements in field investigation guidelines and institutional practices.