United Kingdom fire investigators use ad hoc adsorbents to investigate the suspected use of ignitable liquids and their residues (ILR) at fire scenes. It was unknown whether these materials adsorb all ignitable liquid target compounds specified by ASTM methods, or if they interfered with such analysis and therefore prevented the positive identification of ignitable liquids. This research has ascertained that adsorbents such as clay based cat litter, montmorillonite, limestone, Tampax®, Tenalady®, talc; sand and the use of a squeegee tool cannot adsorb the full range of ASTM target compounds in common ignitable liquid residues by themselves. However, some can adsorb a limited range of target compounds. For example, cat litter can adsorb C3 and C4 alkylbenzenes and other molecules for the identification of petrol, but cannot adsorb heavy alkanes such as those found in diesel fuel. In contrast, limestone can adsorb heavy alkanes but not all aromatic target compounds present in petrol. This study has found that when limestone was mixed with Fuller’s Earth (10:1 w/w) that a range of common ignitable liquids and their associated target compounds could be adsorbed and identified. Furthermore, the instrumentation and separation methods used with an automated thermal desorption-gas chromatography-mass spectrometer (ATD-GC-MS) and Tenax TA® were improved and it is hoped that these would form a basis for a new standard method. Limestone and Fuller’s Earth as well as the limestone/Fuller’s Earth mixture were characterised with Fourier-Transform Infra-Red spectroscopy and X-ray Diffraction. The results showed that mixing the components together did not alter the chemical composition of the adsorbent mixture and that the major phases in the mixture were identified as calcite, quartz and palygorskite. The performance of the adsorbents was assessed using a combination of a standard ASTM method for analysis using GC-MS and an improved oven separation time of six to nine hours. The ATD method was improved for real fire debris samples by setting the split flow valves to 40 mL/min to minimise instrument overloading. The adsorbents were subjected to evaluation in the laboratory using blind tests and also a field blind test at a real fire scene. The laboratory analysis and fire scene evaluation revealed that the limestone/Fuller’s Earth mixture adsorbed all ignitable liquid target compounds from different ignitable liquids and as a result were identified from extracted ion chromatograms. This is the first reported use of this novel mixture as a universal adsorbent for common ignitable liquids.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:694699 |
| Date | January 2014 |
| Creators | White, Garry |
| Publisher | Anglia Ruskin University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://arro.anglia.ac.uk/700895/ |
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