Progressive dehydration in decomposing bone: a potential tool for forensic anthropology
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Progressive dehydration in decomposing bone: a potential tool for forensic anthropology Steven J. Walden1 · Sam L. Evans2 · Jacqui Mulville3 · Karen Wilson4 · Scott Board4 Received: 17 November 2018 / Accepted: 31 July 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract The aim of this pilot study was to determine whether collagen and/or water content of bone vary during soft tissue putrefaction by thermogravimetric analysis with a view to eventually developing a possible forensic application to determine postmortem interval. Porcine bone decomposed in a shallow burial showed an approximate difference in average mass loss of 15 ± 8% when heated between 22 and 100 °C, compared to 14 ± 3% for porcine bone decomposed in a surface deposition, equating to water loss. Mass loss showed peaks at 0, 250–500 and 1200–1500 cumulative cooling degree days’ (CCDD) deposition for the experimental porcine bone. Should these measurements prove consistent in future studies on a wider variety of porcine and eventually human skeletal elements, they may have potential to be corroborated with other data when determining post-mortem interval, especially with disarticulated bones. A downward trend in mass loss was apparent within shallow burial and surface deposition scenarios (inclusive of freeze-dried controls) for the thermolysis of collagen (and other proteins) between 220 and 650 °C during thermogravimetric analysis. This was inconsistent within the time frame examined (0–1450 cumulative cooling degree days), and so demonstrates less potential as an indicator of post-mortem interval during soft tissue putrefaction. Keywords Forensic · Anthropology · Bone · Dehydration · Collagen · Decomposition
Introduction During thermogravimetric analysis, mass loss at a particular temperature over a given period of time illustrates the thermal decomposition of specific molecules and is thus indicative of the chemical composition of the substance [8]. Jong Jin Lim’s 1975 [9] paper ‘Thermogravimetric Analysis of Human Femur Bone’ (Journal of Biological Physics) is arguably the first use of thermogravimetric analysis that is applicable to forensic anthropology. Lim thermally decomposed a 2 mm3 sample of 20 year old human femur bone in air in
* Steven J. Walden [email protected] 1
School of Engineering and School of History, Archaeology, and Religion, Cardiff University, Cardiff, Wales
2
School of Engineering, Cardiff University, Cardiff, Wales
3
School of History, Archaeology, and Religion, Cardiff University, Cardiff, Wales
4
European Bioenergy Research Institute, Aston University, Birmingham, England
the temperature range of 25–1000 °C, for which the differential primary loss curve yielded four distinct peaks. Drawing on previous data from tendon collagen, and known values for water, Lim identified the first mass loss peak between 25 and 200 °C as dissociation of water from collagen, the second significant mass loss peak occurred between 200 and 400 °C and was identified as resulting from the thermal decomposit
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