Potential of soil organic matter molecular chemistry determined by pyrolysis-gas chromatography/mass spectrometry for forensic investigations

Abstract

Wetlands near urban centers may be more isolated areas and can be chosen for the disposal of bodies or used as a crime scene. The predominant soils in these areas usually have a high content of organic matter (OM), classified as Histosols. Soil organic matter (SOM) is composed of many different compounds that can be identified by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The study aimed to use Py-GC/MS to classify small amounts of organic soil in a forensic context. We sampled Histosols from five representative sites of Curitiba, Brazil. The molecular composition of the samples was determined by byPy-GC/MS. The factor analysis was carried out, and the factor scores showed a clear differentiation between the sites. Compounds indicative of relatively fresh plant material was separated from more recalcitrant and charred material. Py-GC/MS has the potential to be a useful tool to study the composition of SOM in Histosols to track the trace sample collected from a crime suspect.

Keywords: Factor analysis; Fingerprint of soil; Histosol; Trace sample; Wetlands.