Heat induced changes in bone and its crystal size: A comprehensive analysis by FTIR-ATR and XRD

Skeletal remains play a vital role in forensic investigations, especially in cases involving prolonged decomposition, burning, or mutilation to obscure evidence. Bone is a complex material primarily composed of Hydroxyapatite (a Calcium Phosphate compound) and other minerals, collagen, non-collagenous proteins, lipids, cells and vascular tissue. While previous researches have explored the effects of temperature and duration of burning on bone but they often lack a systematic examination of how these parameters affect the morphology and internal structure of bone mineral. Additionally, most of the previous research have predominantly used animal bone as a sample instead of human bone, which may not accurately represent human bone characteristic under similar conditions. To address this gap, this study acknowledges the difference in the burning characteristics that affects the practicality of the result in forensic cases. and utilizes human femoral bone obtained from unidentified bodies to simulate the burning conditions typical in fire cases. The research examines the impact of temperatures ranging from 200℃ to 1200℃ over durations of 15, 30, 60 and 120 min. Observable changes in bone dimensions and coloration are analyzed, and Fourier Transform Infrared Reflectance (FTIR-ATR) is used to assess changes in mineral composition. Additionally, X-Ray Diffraction (XRD) is used to measure changes in bone crystallinity, revealing a decrease in crystal size due to organic component loss and a spike in crystal size at higher temperatures due to the formation of tricalcium phosphate from hydroxyapatite. These findings provide valuable insights into the thermal degradation of human bones, enhancing the accuracy of forensic investigations involving extreme thermal conditions.