Using solid phase microextraction and gas chromatography/mass spectrometry when analyzing fire debris for pseudoephedrine, a prescursor drug in clandestine methamphetamine production
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The production of methamphetamine in clandestine laboratories presents a particular hazard due to the environmental hazards it poses. In addition to the dangers associated with using caustic and reactive solvents, these clandestine laboratories also have to potential to cause a fire or explosion. This danger has caused some states to redefine arson to include fires caused by the illicit manufacture of drugs. Arson investigation can be challenging due to the destructive nature of the crime. Much of the evidence that existed prior the fire can be consumed and evidence that does survive can be difficult to identify in the rubble. Despite these difficulties, methods have been developed to determine the types of accelerants present in addition to identifying illicit substances such as methamphetamine and the precursor drug pseudoephedrine. This study was designed to determine if solid phase microextraction combined with gas chromatography/mass spectrometry could be used to analyze burned samples of wood to which pseudoephedrine had been applied. In addition, an experiment was designed to determine what concentration of pseudoephedrine must be present before a fire in a controlled laboratory setting, for a detectable amount to remain. Samples were created by adding pseudoephedrine hydrochloride, either in powder form or dissolved in methanol, to blocks of Douglas Fir and exposing the surface to a flame for two minutes. Additional samples were created by adding trace amounts, i.e. microliter quantities, of pseudoephedrine standard to blocks of wood before placing them in a fire for ten minutes. A thermal degradation product of pseudoephedrine was detected in samples containing more than 15 mg of the drug. To verify that the detected product was a result of thermal degradation, 10 mg of pseudoephedrine were heated at 200 °C for one hour. The product of the thermal degradation study and the product detected following two minutes of exposure to a flame had the same retention time and mass spectrum. Therefore, it was concluded that the detected thermal degradation product may be used to indicate the presence of pseudoephedrine in a fire.