Human and non-human bone identification using FTIR spectroscopy.

Area of Science:

• Forensic Science
• Anthropology
• Analytical Chemistry

Background:

• Traditional bone identification methods are subjective and time-consuming.
• Accurate species identification of skeletal remains is crucial in forensic and anthropological investigations.
• Developing objective and efficient methods is essential for forensic casework.

Purpose of the Study:

• To evaluate Fourier transform infrared (FTIR) spectroscopy combined with chemometrics for differentiating human and non-human bone species.
• To assess the method's effectiveness across various bone conditions (fresh, boiled, decomposed).
• To identify spectral markers indicative of species and postmortem changes.

Main Methods:

• Fourier transform infrared (FTIR) spectroscopy was used to analyze bone samples.
• Chemometric techniques, including Principal Component Analysis (PCA) and Partial Least Squares Discriminant Analysis (PLS-DA), were applied.
• Bones from humans, pigs, goats, and cows, in fresh, boiled, and decomposed states, were analyzed.

Main Results:

• PCA indicated pig bones are highly sensitive to environmental factors, making them less suitable as human bone proxies.
• PCA showed clear separation between fresh human and non-human bones, but struggled with boiled/decomposed samples.
• PLS-DA achieved high classification accuracy (99.72% internal, 99.53% external validation).
• Spectral variations were primarily attributed to stable inorganic components like carbonates and phosphates.

Conclusions:

• FTIR spectroscopy is a reliable tool for bone species determination.
• The method demonstrates significant potential for application in real-world forensic investigations.
• The stability of inorganic bone components contributes to the method's robustness under varying conditions.