ABSTRACT
Chemical analysis of evidence collected from the scene of a fire presents some unique problems. First, the nature of the sample is not standard, and the sample itself can vary greatly in makeup (type of analytes, type of substrate background, size of sample, and target analyte concentrations). Second, the collection of the sample is also not standard in that there is usually some degradation to the target analytes (the ignitable liquid residues used to accelerate a fire). The safety of individuals and the protection of property takes priority over the preservation of evidence; hence, samples are water soaked or sometimes totally consumed in a fire. The target analytes within the sample are volatile or semivolatile, and therefore the collection process is time sensitive. As shown in the preceding chapters, there are adequate laboratory procedures to detect, identify, and classify ignitable liquid residue (ILR) evidence from the fire scene. The major weakness in the process of evidence analysis during a fire investigation is related to the sampling and the sample preparation step. Finally, it is very straightforward to determine either (1) high quantities of analytes in the presence of a complex and possibly interfering matrix or (2) low levels of analytes in a sample devoid of interfering species.
