A fire debris analysis is usually conducted to determine the origin, and the cause of the fire. This implies that the debris is often collected from the scene after having established a number of things. First, fire needs fuel and oxygen. This means that there must be oxygen and combustibles, either in arson or accidental fire. In this case, all fire investigations begin with establishing the materials that fuelled the fire. These usually include furniture, carpets, drapes, upholstery among other things. These materials often contain polymers that are similar to those in petroleum products and, therefore, establishing their presence and state is vital in structuring the relevant mode of analysis. This paper delves into the analysis of fire debris from the scene of the fire, all the way into the laboratory.

At the Scene

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At the scene of the fire, it is important to note that fire burns in an upward pattern usually creating a V shape (Stauffer, Dolan and Newman 2008, p. 67). This means that at the source of the fire, the walls are likely to have a V pattern implying that the fire started there. However, Bogusz (2008, p. 71), established that fires that are started intentionally usually have the accelerants poured in various points. This implies that there will be numerous areas of concentration other than the starting point with regards to the accelerants used. To capture this, it is important to look out for different temperature zones where by the highest intensity is symbolic of the presence of an accelerant.

To determine the cause of the fire, debris should be collected from the established source, as well as, the areas that hard the highest fire intensity. This debris should then be examined using a sniffer to affirm the presence of an accelerant (Ubelaker 2013, p.16). The sniffer uses a flame ionization detector or a catalytic oxidation probe as the working mechanisms. This method is better than relying on one's sense of smell due to variations in smell sensitivity and the toxicity of the fire scene in terms of residual fumes (Frysinger and Gaines 2002). However, the sniffer only determines the presence of an accelerant, without really specifying whether it was accidental or intentional.

Upon determining accelerants in the fire debris, the samples are then collected in air tight containers, usually not plastic or polythene to avoid contamination (Tondu 2008, p. 241). The samples are then transported to a laboratory for further analysis. In addition, considering that fire requires oxygen to burn, the accelerants that may have seeped through cracks or tiles may not have been able to burn. Thus, care should be taken while examining such surfaces, as they may not only provide evidence of an accelerant, but also narrow it down to the one that was specifically used in that case.

At the Laboratory

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There are two basic options for analyzing fire debris at the laboratory (Lynch 1986). First of all, it is important to note that the debris has already been affirmed to be containing ignitable compounds, and the laboratory analyst only requires establishing whether the accelerant was a modern substrate or simply a fire starter. This is where cases of arson can be fully detected beyond reasonable doubt (Bibel 2008). Moreover, it is important to have comparison standards for possible compounds used to start the fire, as well as, for the components of the debris, such as, carpets, furniture, drapes, among others. All these will help in the identification and elimination process while narrowing down the suspected compounds list.

The first option is, thus, using a gas chromatography with flame ionization detection (GC/FID). This method is a good option where the suspected compounds are volatile flammables (Almirall and Furton 2004, p. 54). It is not able to narrow the suspects' list to a particular compound, however, since it can only give wide results. This method is, therefore, the best option when dealing with hydrocarbon based accelerants, and it is relatively cheap in terms of work done and expertise required to interpret results.

The second option involves the use of gas chromatography with mass spectromic (GC/MS). This method is not only expensive, but it also requires an extensive mastery of the mass spectrometry in order to perform and interpret the results obtained (Kobilinsky 2012). However, the method enables a thorough analysis as the culprit compound is identified beyond reasonable doubt. All the present compounds are analyzed and compared with the comparison standards to eliminate the residues from modern substrates found in furniture, carpets and other items that may have contributed to the composition of the fire debris aside from the accelerants. After this comparison and elimination, the exact compound that started the fire can be named and traced right to its brand name and thence source.


After determining the source of a fire and picking out samples where the accelerant is most likely to be present, it is important to use a sniffer to ascertain that there exists an ignitable compound before committing to a definitive laboratory analysis. Sniffers are not only highly accurate, they eliminate the danger of sniffing the debris with high levels of toxic compounds. For transporting the debris to the laboratory, plastic containers and polythene bags should be avoided so as not to contaminate the debris. A GC/FID is a relatively cheaper method of determining the presence of hydrocarbon based ignitable compounds in the fire debris, and it is also easy to carry out and interpret. However, for more specified results the more expensive and specialized GC/MS is recommended. For accuracy, comparison standards are recommended so as to ensure that all sources of doubt are eliminated in the final report.

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