"DART-HRMS and chemometric analysis for applications in forensic entomo" by Amy Marie Osborne

Date of Award

1-1-2023

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School/Department

Department of Chemistry

Content Description

1 online resource (xviii, 956 pages) : illustrations (some color)

Dissertation/Thesis Chair

Rabi A Musah

Committee Members

Jennifer Y Rosati, Mehmet Yigit, Ting Wang

Keywords

Chemometrics, DART-HRMS, Entomology, Forensic, Forensic entomology, High resolution spectroscopy

Subject Categories

Chemistry

Abstract

Forensic entomology, the utilization of insects in the course of legal investigations, is a broad field which encompasses three main branches: medico-legal, stored-product, and urban. This body of research focuses on the first two branches. The first branch, medico-legal forensic entomology, generally applies to death investigations. In death investigations it is imperative to establish the time since death (postmortem interval) and cause of death. Both of these queries can be difficult to assess for remains that are in mid- to late- stages of decay. Carrion insects found on and near the body can assist forensic investigators in this task, as there is a well-established correlation between a given stage of decomposition, and the insect species that colonize the remains. Since the timeline associated in the insect progression through various life stages is heavily documented, knowledge of the species of the retrieved entomological evidence can be used to calculate PMI. Further, since the insects which colonize remains commonly do so in order to use the remains as a primary food source, toxicological information obtained from the analysis of the insects can be used to infer information about the bioaccumulation of illicit substances or other toxins which have come from the body. This is known as entomotoxicology. The conventional approaches used in entomotoxicological analysis, which is still a nascent field, rely on painstaking and/or cumbersome, resource-intensive and time-consuming analyses which require lengthy sample preparation steps, leading to an underutilization of entomological evidence in forensic investigations. Direct analysis in real time-high-resolution mass spectrometry (DART-HRMS) can be used to determine metabolome profiles of the insects, and in turn, this information can be processed through multivariate statistical analysis to determine critical information about the insect evidence. Interspecies differences and intraspecies similarities between insect specimen chemical signatures facilitate determination of insect species identity. While this has been previously established for blow flies (Order: Diptera), Chapter 2 of this work endeavored to expand this application to necrophagous beetles (Order: Coleoptera). Furthermore, the consumption of illicit substances by insects can cause changes to their metabolome profiles in comparison to controls, allowing for the screening of entomological evidence to determine if toxicological information can be inferred from insects. In Chapter 3, chemometric analysis of blow flies in various life stages facilitated the differentiation of insects which fed on fentanyl-derivative-laced liver from those which fed on control liver, which did not contain any fentanyl-based compounds.The second branch of forensic entomology (stored-product entomology) refers to the utilization of insect species identity and life stages to determine the cause and length of infestation in post-harvest agricultural products. Many traditional techniques rely on visual inspection of the products, which is a time-consuming and subjective endeavor. However, insects can leave chemical traces of their presence in stored-products which can be revealed through DART-HRMS analysis of the stored-products under investigation. In Chapter 4, DART-HRMS was utilized to screen milled flour for traces of a common pest, Tribolium castaneum, the red flour beetle. Statistical analysis techniques were used to highlight the important m/z values contributing to the differences in flour samples and differentiate infested and un-infested flour. The results of this research have the potential to lead to rapid techniques by which beetle species can be identified, blow flies can be assessed for toxicological information, and flour and other grains can be tested for insect infestation.

Download

Included in

Chemistry Commons

Share

COinS