Solid-phase microextraction analysis of volatile organic compounds in the headspace of decomposing bodies

Abstract

Introduction: The ability to find human remains as well as locating surfaces that previously have been exposed to human remains, is essential for crime solving and is widely known throughout the whole forensic community to be a complex process.

Background: Human bodies will undergo a decomposition process that generates volatile organic compounds (VOCs). The scientific community has been evaluating existing methods to detect these compounds, such as the use of canines and gas sensors. Unfortunately, these methods have limitations that reduce their reliability.

Aim(s): The aim of this study is to explore the feasibility of achieving repeatable sampling of volatile organic compounds (VOCs) from decomposed tissue using headspace solid-phase microextraction (HS-SPME), focusing on concentration and identification profiles. The collected samples will undergo analysis using gas chromatography-mass spectrometry (GC/MS).

Methods: A PDMS fiber was used to trap VOCs from a chemical mixture and from a decomposing chicken. Extracted VOCs were analyzed by GC/MS.

Results: Significant variability is observed across all generated data. Nevertheless, successful extraction of chemicals from decomposed chicken was accomplished, although only one of these chemicals could be conclusively identified.

Conclusion: HS-SPME combined with GC/MS shows potential as a method for collecting and analyzing volatile organic compounds (VOCs) from decomposed tissue. However, further experiments are essential to tackle issues related to poor precision.

Popular Abstract

It is important to be able to identify surfaces where corpses have been in order to solve crimes. When a person dies, a decomposition process begins that releases various volatile organic compounds (chemicals) into the surrounding environment. These chemicals also stick to surfaces, and therefore the chemicals can be used to connect a surface to a body. However, the methods currently available to locate these surfaces are not that reliable. The long-term aim of this project is therefore to develop a new scientific method to detect surfaces exposed to corpses.

To make this possible, an instrument containing something that looks like a small thin needle, a so-called fiber, is used. The various chemicals from the environment can stick to such a fiber. The fiber is then injected into another instrument, the chemicals are detached from the fiber and enter the instrument which separates the chemicals from each other. The chemicals then go into a third instrument that helps identify which chemicals are involved. Depending on a number of parameters such as humidity, time, temperature etc. different patterns of chemicals are generated from the surface. Therefore, one also wants to use the information obtained from the instruments to create a model that describes how these patterns change depending on these different parameters. This model can then be helpful for the identification of the corpse.

This is a large project that requires a longer period of work and therefore this report aims to describe the improvement of the precision of the method, i.e., the ability of the method to always provide consistent results. While the described technique shows promise as a method for analyzing surfaces exposed to corpses, the drawn conclusion emphasizes the need for additional work to enhance the precision of the method.

• author: Bäckström, Isabelle
• supervisor: Peter Spégel
• organization: Department of Chemistry; Computational Chemistry
• course: KEMR20 20231
• year: 2024
• type: H2 - Master's Degree (Two Years)
• subject: Chemistry
• keywords: Cadaver, GC/MS, SPME, VOCs, analytical chemistry
• language: English
• id: 9148660
• date added to LUP: 2024-02-19 08:53:45
• date last changed: 2024-02-19 08:53:45