Comparative Evaluation of Ignitable Liquid Residue Detection by GC/MS and DART-MS

Description:
Ignitable liquids (ILs) are commonly used as accelerants in arson attacks to initiate and intensify fires. The identification and accurate determination of the ignitable liquid residues (ILR) are critical to providing an evidentiary link between the arson and the suspect. In forensic labs, gas chromatography coupled with mass spectrometry (GC/MS) is used for the identification and classification of the unknown ILR from fire debris by following the American Society for Testing and Materials (ASTM) methods (e.g., E1618). The GC/MS is capable of analyzing the volatile components in the ILR; however, it is necessary to characterize the non-volatile or less volatile components for the identification of the ILs. Recently, our group has developed direct analysis in real-time mass spectrometry (DART-MS) method for the detection of ILs and found unique less volatile marker compounds in ILs, which are not commonly observed with GC/MS methods. The spectral profiles for ILs from DART-MS analysis have shown high resistance to the weathering process, and the detection of the less volatile marker compounds, such as polyisobutylene succinimides and polyether amines in gasoline and glycol ether derivatives in paint thinner, could have a significant value for the detection of ILR because they are more likely to be retained after weathering or even burns. Both GC/MS total ion chromatogram (TIC) and DART-MS data produce discriminative data profiles for IL classification, and DART-MS can be complementary to the existing GC/MS method for the identification of ILs.
In this presentation, we will compare the chemical profiles of ILs from both GC/MS and DART-MS analysis and discuss the unique capability of DART-MS for the detection of compounds specific or unique for each type of ILs. In addition, a sorbent tube-based versatile sampling strategy will be introduced to reduce the matrix interference from the substrates and fire debris.

Speaker: Mengliang Zhang - Middle Tennessee State University