Differentiating present-day from ancient bones by vibrational spectroscopy upon acetic acid treatment

• Published in: Forensic science international 2023-06, Vol.347, p.111690-111690, Article 111690
• Main Authors: Brandão, A.L.C., Batista de Carvalho, L.A.E., Gonçalves, D., Piga, G., Cunha, E., Marques, M.P.M.
• Format: Article
• Language: English
• Subjects: Acetic Acid; Acids; Archaeology; Body Remains; Bone and Bones - chemistry; Bone composition; Bones; Calcium hydroxide; Carbon dating; Carbonate content; Carbonates; Carbonates - analysis; Chemical composition; Contaminants; Controlled burning; Cremation; Forensic anthropology; Forensic sciences; Fourier transforms; FTIR-ATR spectroscopy; Heat; Human remains; Humans; Hydroxyapatite; Infrared spectroscopy; Iron Age; Morphology; Pollutant removal; Post-mortem interval; Raman spectroscopy; Slaked lime; Spectroscopy; Spectroscopy, Fourier Transform Infrared - methods; Spectrum analysis; Washing
• ISSN: 0379-0738; 1872-6283
• DOI: 10.1016/j.forsciint.2023.111690

Acetic acid treatment for an accurate differentiation between ancient and recent human bones was assessed using Raman and FTIR-ATR spectroscopies. Each set of skeletal samples was analysed by these techniques, prior and after chemical washing, in order to determine the variations in bone´s chemical composition and crystallinity. Bone samples were collected from several independent sources: recent bones burned under controlled experimental conditions or cremated, and archaeological (XVII century and Iron Age). The effect of acetic acid, expected to impact mostly on carbonates, was clearly evidenced in the spectra of all samples, particularly in FTIR-ATR, mainly through the bands typical of A- and B-carbonates. Furthermore, as seen for crematoria and archaeological samples, acetic acid was found to remove contaminants such as calcium hydroxide. Overall, acetic acid treatment can be an effective method for removing carbonates (exogenous but possibly also endogenous) and external contaminants from bone. However, these effects are dependent on the skeletal conditions (e.g. post-mortem interval and burning settings). In addition, this chemical washing was shown to be insufficient for an unequivocal discrimination between recent and archaeological skeletal remains. Based on the measured IR indexes, only cremated bones could be clearly distinguished. [Display omitted] •Optimal experimental conditions were obtained with acetic acid 0.1 M for 4 h.•Acetic acid treatment removed carbonates and calcium oxides from bones.•C/C index distinguished gas-fuelled crematorium samples from other samples.