Detection Of Ignitable Liquid Residues Research Articles

Detection of gasoline residues on household materials up to 60 days: Comparison of two extinguishing methods

Detection of ignitable liquid residues in a fire scene is essential for determining the origin. Although studies are focused on the detection of residues of accelerants depending on time or matrices, the time-dependent effect of the water extinguishing method in a fire has not yet been investigated. Experimental studies are needed to determine how long ignitable liquid residues can be detected in water-extinguished evidence compared to the smothering method. In this study, the effects of both extinguishing methods on gasoline residues were investigated after burning of carpet, sofa fabric, tablecloth, and towel by Solid Phase Micro Extraction- Gas Chromatography/Mass Spectrometry (SPME-GC/MS) technique. Four mandatory and 14 additional compounds were considered to prove the gasoline residue after the monitoring of possible interferences. Results showed that gasoline residues on the burned carpet and sofa fabric samples were successfully detected in both extinguishing methods up to 60 and 30 days after fire exposure, respectively due to multi-layered structures of related substrates. Additionally, the prolonged detection time of the water-extinguishing method made it particularly beneficial for single-layered products like tablecloths, where gasoline residues were found after an hour in this substrate. This is the first study investigating the effects of the extinguishing methods depending on time for textile products, which are the most used materials in houses. In addition, the fact that acrylamide-containing sofa fabric was investigated for the first time and that gasoline residues in carpet samples can be detected up to 60 days makes this study stand out.

Developing a Method for the Collection and Analysis of Burnt Remains for the Detection and Identification of Ignitable Liquid Residues Using Body Bags, Dynamic Headspace Sampling, and TD-GC×GC-TOFMS

In cases of suspected arson, a body may be intentionally burnt to cause loss of life, dispose of remains, or conceal identification. A primary focus of a fire investigation, particularly involving human remains, is to establish the cause of the fire; this often includes the forensic analysis of fire debris for the detection of ignitable liquid residues (ILRs). Commercial containers for the collection of fire debris evidence include metal cans, glass jars, and polymer/nylon bags of limited size. This presents a complication in cases where the fire debris consists of an intact, or partially intact, human cadaver. This study proposed the use of a body bag as an alternative sampling container. A method was developed and tested for the collection and analysis of ILRs from burnt porcine remains contained within a body bag using dynamic headspace sampling (using an Easy-VOC™ hand-held manually operated grab-sampler and stainless steel sorbent tubes containing Tenax TA) followed by thermal desorption comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (TD-GC×GC-TOFMS). The results demonstrated that a body bag containing remains burnt with gasoline tested positive for the presence of gasoline, while blank body bag controls and a body bag containing remains burnt without gasoline tested negative. The proposed method permits the collection of headspace samples from burnt remains before the remains are removed from the crime scene, limiting the potential for contamination and the loss of volatiles during transit and storage.

Effects of Fire Suppression Agents and Weathering in the Analysis of Fire Debris by HS-MS eNose.

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).

Field test kits for collection of ignitable liquids and ignitable liquid residues used by the NSW fire scene investigators

The detection of ignitable liquid residues (ILR) on samples related to fire scenes provides investigators with important information. Field test kits were developed as an alternative procedure to swabbing using cotton wool and cotton tip applicators for situations where direct sampling is not possible. Central to the kits is a piece of white absorbent non-woven material consisting of polypropylene fibres (cloth). Experiments were carried out in our laboratory using the polypropylene cloths and cotton wool for collection of burnt and unburnt petrol residues from porous and non-porous surfaces. Every aspect of this new procedure was validated, involving more than 200 analyses of fire debris samples, where the polypropylene cloth was used to sample ILR comprising all common accelerants. The use of field test kits for collection of petrol and medium petroleum distillate (MPD) residues from hands was validated on the hands of 11 volunteers. The polypropylene cloth was found to be suitable for application in field test kits for the collection and recovery of petroleum-based liquids and liquid residues from both fire scenes and hands.

Preliminary evaluation of a next-generation portable gas chromatograph mass spectrometer (GC-MS) for the on-site analysis of ignitable liquid residues

The detection of ignitable liquid residues (ILRs) at a fire scene can be valuable evidence to indicate if the fire may have been deliberately set. In this study, a commercially-available portable GC-MS, the TRIDION-9, was evaluated for the purpose of on-site fire debris analysis. The instrument, which incorporates a low thermal mass capillary GC and a miniaturised toroidal ion trap mass spectrometer, is designed to use solid-phase microextraction (SPME) as the default sampling method. Four ignitable liquids (petrol, mineral turpentine, kerosene and diesel) and seven substrates (nylon, polypropylene and wool carpet, rubber and foam underlay, untreated pine and polyurethane) were considered. After method optimisation, substrates were burned and spiked with 0.1 μL of ignitable liquid (mineral turpentine, kerosene, diesel fuel, and both neat and weathered unleaded petrol). Sampling was performed via passive headspace SPME adsorption over 3 min immediately followed by analysis using the TRIDION-9 (analysis time < 2 min). Field trials were performed on fire debris samples collected from an accelerated structural fire. The data from the portable GC-MS analyses permitted the detection and correct classification of ILRs in the majority of samples analysed. Overall, the TRIDION-9 was found to be well-suited to the field-based analysis of fire debris samples as a preliminary screen to provide rapid presumptive results for fire investigators.

Application of an HS–MS for the detection of ignitable liquids from fire debris

In arson attacks, accelerants such as ignitable liquids are commonly used to initiate or accelerate a fire. The detection of ignitable liquid residues at fire scenes is therefore a key step in fire investigations. The most widely used analytical technique for the analysis of accelerants is GC–MS. However, pre-concentration of the ignitable liquid residues is required prior to the chromatographic analysis. The standard method, ASTM E1412, involves passive headspace concentration with activated charcoal strips as a method to isolate the ignitable liquid residues from fire debris and these residues are subsequently desorbed from the carbon strip with solvents such as carbon disulfide.In the work described here, an alternative analytical technique based on an HS–MS (headspace mass spectrometry) has been developed for the thermal desorption of the carbon strips and analysis of different ignitable liquid residues in fire debris. The working conditions for the HS–MS analytical procedure were optimized using different types of fire debris (pine wood burned with gasoline and diesel). The optimized variables were desorption temperature and desorption time. The optimal conditions were 145°C and 15min.The optimized method was applied to a set of fire debris samples. In order to simulate post burn samples several accelerants (gasoline, diesel, citronella, kerosene, paraffin, and alcohol) were used to ignite different substrates (wood, cotton, cork, paper, and paperboard). chemometric methods (cluster analysis and discriminant analysis) were applied to the total ion spectrum obtained from the MS (45–200m/z) to discriminate between the burned samples according to the accelerant used. The method was validated by analyzing all samples by GC–MS according to the standard methods ASTM E1412 and ASTM E1618. The results obtained on using the method developed in this study were comparable to those obtained with the reference method. However, the newly developed HS–MS method is faster, safer, and more environmental friendly than the standard method.

A New Method for the Detection of Ignitable Liquid Residues on Arsonist Suspects Hands

In most investigations the investigator focuses on the circumstances under which a fire breaks out. In cases of arson the investigator has another significant task—to link the suspect to the fire and scene of crime. One method is to examine the suspect’s palms for flammable residue consistent with the substance used at the crime scene. In the past several methods were suggested to sample hands. These methods, however, all have a shortcoming: either they suffer from low sensitivity, or they are impractical to use under field conditions. This article presents a new and innovative method with high sensitivity and simple to use in the field. The method is based on passive adsorption using a charcoal strip placed on hands that are placed into a sealed bag for an hour. This is done in the field or in a police station immediately after the arrest of a suspect. The charcoal strip is sent to the laboratory for examination to determine if flammable traces are present. This method was introduced into use in Israel in 2010 and has led to positive results in numerous cases.

98/04297 Method and device for detecting unburnt carbon in fly ashes from coal firing boiler by using micro wave

The detection of ignitable liquid residues (ILR) on samples related to fire scenes provides investigators with important information. Field test kits were developed as an alternative procedure to swabbing using cotton wool and cotton tip applicators for situations where direct sampling is not possible. Central to the kits is a piece of white absorbent non-woven material consisting of polypropylene fibres (cloth). Experiments were carried out in our laboratory using the polypropylene cloths and cotton wool for collection of burnt and unburnt petrol residues from porous and non-porous surfaces. Every aspect of this new procedure was validated, involving more than 200 analyses of fire debris samples, where the polypropylene cloth was used to sample ILR comprising all common accelerants. The use of field test kits for collection of petrol and medium petroleum distillate (MPD) residues from hands was validated on the hands of 11 volunteers. The polypropylene cloth was found to be suitable for application in field test kits for the collection and recovery of petroleum-based liquids and liquid residues from both fire scenes and hands.