Characterisation of skeletal remails using field portable Fourier Transform Infrared (FTIR) spectroscopy in an Australian temperate environment

Abstract

Estimation of time since death is imperative in forensic investigations, yet it is one of the most challenging and unresolved aspects. Currently, anthropologists are often given the task of differentiating human from non-human bone and assessing postmortem interval (PMI) based on skeletonised remains alone, which is difficult, especially with fragmented bone or lack of typical bony features. An accurate PMI estimation can aid in determining an accurate timeframe, differentiating between peri- and most-mortem activities, narrowing down the search for missing persons and improving the safety of investigators. This study aimed to determine whether portable Fourier Transform Infrared (FTIR) spectroscopy was an appropriate and efficient method for analysing skeletal remains in the field. Human remains were compared to non-human remains to ascertain whether differences were seen based on species differentiation or PMI. This study utilised several skeletonised pig carcasses, placed on a soil surface, and eight human cadavers donated to the Australian Facility for Taphonomic Experimental Research (AFTER). One femur and one rib from each individual were used in this study. Spectra produced by Smiths HazMatID 360 System portable FTIR showed consistent results across all femur and rib samples with well-defined bands in the area of interest according to published literature. The results obtained in this study for amide I, 𝜈3(CO32-), 𝜈3(PO43-), 𝜈1(PO43-) and 𝜈2(CO32-) infrared (IR) bands were all visually similar to published research on pig and human remains. Six-monthly PMI intervals are probably too narrow to provide an accurate PMI estimation using field portable FTIR spectroscopy, however, potential is shown for longer time intervals of 1.5 years. This research shows a clear difference between pigs and humans for all IR bands within the area of interest (1800-650 cm-1). This may be attributed to species differentiation and/or PMI. Consistent patterns in skeletal remains with the strongest phosphate (PO3-) band being at 1015 cm-1 in human remains and 1020 cm-1 in pig remains, shows a promising result to distinguish human from non-human remains and/or PMI estimation using portable FTIR.

Date of Award	2023
Original language	English
Awarding Institution	Western Sydney University
Supervisor	Hayley Green (Supervisor)