Determination of biogenic amines in decomposition odor using gas chromatography mass spectrometry

WCU Author/Contributor (non-WCU co-authors, if there are any, appear on document)
Mackenzie Renee Wisor (Creator)
Western Carolina University (WCU )
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Nuwan Perera

Abstract: In a forensic investigation of missing persons or a suspected murder the detection of the corpse is often the most important piece of evidence. Human remain detection dogs (HRD) are the most common method used in locating human remains. Although these dogs are useful in distinguishing between animal and human remains little is known about how they are able to do this. The HRD dog’s ability to detect human remains depends on volatile organic compounds (VOCs) that are emitted during decomposition. Previous studies reported that a variety of different compounds including acids, alcohols, ketones, sulfides, and nitrogen containing compounds are present in decomposition odor. Although these researchers found a variety of compounds they do not report the presence of biogenic amines like putrescine and cadaverine. These amines are produced during the decomposition process through decarboxylation of amino acids and is responsible for the distinct odor released by decomposing corpses. Our hypothesis is that these biogenic amines are not being detected due to the limitation of the analytical methods used by other researchers. Primary amines often have high basicity, high polarity, and low volatility compared to other VOCs, they tend to absorb and decompose in the GC column, sample vessels, and injection system making them hard to detect in low concentrations and difficult to analyze using GC-MS. To obviate this problem, our goal is to develop an analytical method to analyze these amines by derivatizing them before the introduction into the GC system. Reacting with a suitable derivatization agent these amines can be converted into more volatile and less polar derivatives making analysis by GC-MS a feasible method. Several derivatization methods were used. One was a method that used tetrafluoroacetylacetone (FAA) in a Schiff base reaction and another used pentafluoroproponic anhydride (PFPA) in an acylation reaction and neither produced the results that was desired so a different method was used. The current reaction is formation of carbamates using chloroformates. This reaction is particularly used on primary, secondary, tertiary amines, and is generally less reactive with water. To use a chloroformate derivatizing agent it has to be in a pH controlled environment to complete the reaction. To extract them for analysis via liquid-liquid extraction toluene is used. Isobutyl chloroformate was the specific derivatizing agent used and was chosen for its higher peak response with the derivatives. This has yielded clear and constant data that has indicated that the amines are being derivatized by the isobutyl chloroformate and that they can be detected in the GC-MS reliably. A calibration curve was made to fulfill the second goal of derivatization which is to quantify the amines. This method was also used on various soil samples and pseudo scent products to explore the practical application of this derivatization method. Amines were found in most of the practical samples tested and were quantified.

Additional Information

Language: English
Date: 2021
amines, decomposition, derivatization, GC-MS, pseudo corpse, soil
Gas chromatography
Mass spectrometry

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