Abstract
In a fire investigation the rapid detection of the presence of ignitable liquids like gasoline is of great importance as it allows appropriate treatment of the remains, the identification of prevention methods and detects the possible presence of an arsonist. In some cases, analysts cannot access the fire scene in the first few hours due to the dangers involved in the situation and, as a consequence, phenomena such as weathering start. Ignitable liquid weathering is an evaporation process that results in an increase in the abundance of non-volatile compounds relative to volatile compounds, and this process changes the chemical composition. In the present work, the weathering of samples of gasoline at different times (from 0 h to a month) has been studied using an electronic nose (eNose). The influence of the volume used (40 µL and 80 µL) and the type of support (cork, wood, paper and cotton sheet) has been studied. Chemometric tools have been used with the aim of ascertaining the weathering time for which the developed method is capable of detecting the presence of gasoline. The eNose was able to discriminate samples of weathered gasoline. The support used for the samples did not seem to have an influence on the detection and the system.
Highlights
Fires around the world and the consequent material and human damage are becoming a significant problem in our society, given that human activity is responsible for most cases
The most common ignitable liquids used as accelerants in arson attacks are gasoline, diesel and kerosene; especially the former due to it is ready availability and its more rapid combustion when compared to ignitable liquids [2,3,4]
The porosity of the material used did not appear to make any difference in the weathering process, that is, the nature of the supporting material for the sample was unimportant, as the electronic nose (eNose) system had the same capability to discriminate between similar groups
Summary
Fires (mainly forest fires) around the world and the consequent material and human damage are becoming a significant problem in our society, given that human activity (accidentally or intentionally) is responsible for most cases. The eNose has been successfully optimized and validated for the analysis of ignitable liquids in fire debris and has provided characteristic fingerprints [37,38], for thermal desorption of ILR from carbon strips [1], for the discrimination of gasoline samples with different RON (Research Octane Number) [39,40], and for the characterization of neat ignitable liquids [41]. This technique has never been applied to the analysis of ignitable liquids after weathering. The objective of the work described here was to study the evolution/modification of the eNose gasoline fingerprint after an evaporation weathering process for different times (from 0 h to 1 month) using different volumes and substrates of different natures in order to check the capacity of the eNose in the identification of weathered IL samples
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