Abstract
In arson attacks the detection of ignitable liquid residues (ILRs) at fire scenes provides key evidence since ignitable liquids, such as gasoline, are commonly used to initiate the fire. In most forensic laboratories gas chromatography-mass spectrometry is employed for the analysis of ILRs. When a fire occurs, suppression agents are used to extinguish the fire and, before the scene is investigated, the samples at the scene are subjected to a variety of processes such as weathering, which can significantly modify the chemical composition and thus lead to erroneous conclusions. In order to avoid this possibility, the application of chemometric tools that help the analyst to extract useful information from data is very advantageous. The study described here concerned the application of a headspace-mass spectrometry electronic nose (HS-MS eNose) combined with chemometric tools to determine the presence/absence of gasoline in weathered fire debris samples. The effect of applying two suppression agents (Cafoam Aquafoam AF-6 and Pyro-chem PK-80 Powder) and delays in the sampling time (from 0 to 48 h) were studied. It was found that, although the suppression systems affect the mass spectra, the HS-MS eNose in combination with suitable pattern recognition chemometric tools, such as linear discriminant analysis, is able to identify the presence of gasoline in any of the studied situations (100% correct classification).
Highlights
In many criminal activities that lead to fire, such as arson or bomb attacks, ignitable liquids (ILs) such as gasoline or diesel are commonly used as accelerants
The results showed thefor resulting spectrasamples changed markedly after six spectrum (TIMS) was evaluated by the HS-MSthat eNose neat gasoline poured onto different hours of weathering
The present study was designed to investigate the effect of two fire suppression agents (FSAs) (Cafoam Aquafoam AF-6 and Pyro-chem PK-80 Powder) and delayed sampling times for the identification of gasoline in fire debris samples by HS-MS eNose in conjunction with chemometric tools
Summary
In many criminal activities that lead to fire, such as arson or bomb attacks, ignitable liquids (ILs) such as gasoline or diesel are commonly used as accelerants. An investigation must be carried out and this includes the observation and collection of evidence at the scene. Samples collected from fire scenes are analyzed in a laboratory to determine the presence/absence of ignitable liquid residues (ILRs). The detection of an accelerant at the fire scene can be the difference between classifying a fire as accidental or as arson [1]. Arson is an illegal activity and fire investigation is considered as a forensic science that covers knowledge from various fields [2]. Gasoline is Sensors 2018, 18, 1933; doi:10.3390/s18061933 www.mdpi.com/journal/sensors
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