Browsing by Author "White, Garry"

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    The development of a novel adsorbent for collecting ignitable liquid residues from a fire scene.
    (Elsevier, 2016-09-22) Hall, Sarah; Gautam, Lata; White, Garry
    Different ad-hoc materials are being used to recover ignitable liquid residues (ILRs) when direct sampling is difficult at a fire scene. Our investigations have shown that these are unable to recover all target compounds specified in the ASTM method for the positive identification of ILRs. A novel adsorbent (limestone and British Fuller’s earth; 10:1 w/w) has been developed that is capable of recovering all of the target compounds, applicable to a wide range of ignitable liquids. It does not interfere with the analysis and can easily be used on different surface types. The novel adsorbent was also tested at a cold fire scene where all ILRs were identified. This investigation has proved that ad-hoc materials used by fire investigators are not fit for purpose and could lead to the misinterpretation of evidence in court. Here we propose an inexpensive, innovative and universal adsorbent that could be adopted by fire investigators globally.
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    Ignitable Liquid identification using household adsorbents
    (2012-01) Hall, Sarah; White, Garry; Gautam, Lata
    The standard practice for the separation and identification of ignitable liquids is well established in fire debris analysis. A recent study by The Netherlands Forensic Institute identified passive headspace adsorption as the predominant technique currently in use by its participating laboratories across Europe and subsequent analysis is carried out by gas the use of gas chromatography and a mass spectrometer (GC-MS). Whilst it is accepted that GC-MS is the best tool for the analysis, the passive headspace stage is not without problems. If samples being analysed are regarded as evidence samples, then it is imperative that the sample is not subjected to any undue contamination and that the separation and identification process employed is simplistic, rugged and repeatable. Activated charcoal in a passive headspace environment is often the sorbent of choice to adsorb volatile ignitable liquids. However, activated charcoal has an affinity towards chemically charged species and therefore will adsorb these compounds in preference to long chain neutrally charged compounds, such as heavy alkanes. Ignitable liquid mixtures containing heavy alkane chains such as biodiesel fuel, fuel oil and diesel fuel will not have all of their compounds adsorbed by a charcoal strip. Also, the use of solvents to elute the analyte from the charcoal strip has been discussed many times with regard to health issues, and because it is an extra step in analyte separation from fire debris it also carries the risk of contamination. This study has led to improvements to the passive headspace technique and also the analytical method when using an automated thermal desorber with GC-MS (ATD-GC-MS). The improved separation process still uses passive headspace diffusion in an oven, but takes advantage of the adsorption properties of Tenax TA to adsorb heavy alkanes. Tests show that oven times are reduced when compared to current techniques and there is no solvent step in the procedure, thus reducing the risk of undue contamination.
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    Improvements to sampling and instrumentation for fire debris analysis using Tenax TA® and ATD-GC-MS.
    (2012-08) Hall, Sarah; White, Garry; Gautam, Lata
    The standard practice for the separation and identification of ignitable liquids is well established in fire debris analysis. A recent study by The Netherlands Forensic Institute identified passive headspace adsorption as the predominant technique currently in use by its participating laboratories across Europe and subsequent analysis is carried out by gas the use of gas chromatography and a mass spectrometer (GC-MS). Whilst it is accepted that GC-MS is the best tool for the analysis, the passive headspace stage is not without problems. If samples being analysed are regarded as evidence samples, then it is imperative that the sample is not subjected to any undue contamination and that the separation and identification process employed is simplistic, rugged and repeatable. Activated charcoal in a passive headspace environment is often the sorbent of choice to adsorb volatile ignitable liquids. However, activated charcoal has an affinity towards chemically charged species and therefore will adsorb these compounds in preference to long chain neutrally charged compounds, such as heavy alkanes. Ignitable liquid mixtures containing heavy alkane chains such as biodiesel fuel, fuel oil and diesel fuel will not have all of their compounds adsorbed by a charcoal strip. Also, the use of solvents to elute the analyte from the charcoal strip has been discussed many times with regard to health issues, and because it is an extra step in analyte separation from fire debris it also carries the risk of contamination. This study has led to improvements to the passive headspace technique and also the analytical method when using an automated thermal desorber with GC-MS (ATD-GC-MS). The improved separation process still uses passive headspace diffusion in an oven, but takes advantage of the adsorption properties of Tenax TA to adsorb heavy alkanes. Tests show that oven times are reduced when compared to current techniques and there is no solvent step in the procedure, thus reducing the risk of undue contamination.
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    A novel adsorbent for the recovery and positive identification of ignitable liquids using GC-MS-ATD
    (2015-09) Hall, Sarah; White, Garry; Gautam, Lata
    Through survey results and personal communication with Fire and Scene Investigators it has been reported that non-standard and various adsorbent methods are being used for the recovery of Ignitable Liquid Residues (ILRs) from solid surfaces in a fire scene. Their application is a useful alternative to ‘digging up’ of surfaces, which isn’t always possible. An adsorbent can be left on a suspected area of ILR and then easily recovered for later laboratory analysis. The current adsorbents reported (flour, sanitary products, cat litter and garden lime) have had little research carried out on their ability to aid in the later identification of ILRs. This research provides an additional novel adsorbent which has been compared to those currently described using a standard method and utilising Extracted Ion Gas Chromatography-Mass Spectrometry-Auto Thermal Desorption. The method requires the presence and detection of target molecules in different distillates for a positive identification of the ignitable liquid. A 50:50, petrol/diesel mix was used to cover a range of distillates and both are commonly used to accelerate fire spread. Results have found that none of the presently used adsorbents were able to give a positive identification. However, the novel adsorbent from this research did result in a positive identification of petrol and diesel. Further blind trials and a test burn also resulted in all the ILRs being identified and currently the novel adsorbent is under a patent application as a universal adsorbent for recovery of a wide range of ILRs from a fire scene.