The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

Validation of bone apatite purification protocols for stable isotope analysis in bioarchaeology by Solid-State Nuclear Magnetic Resonance spectroscopy


1UMR 5199 PACEA Anthropologie des Populations Passées et Présentes, CNRS, Université Bordeaux 1, 2UMR 7209 Archéozoologie, Archéobotanique : sociétés, pratiques et environnements, Muséum National d’Histoire Naturelle, 3UMR 5248 CBMN Institute of Chemistry & Biology of Membranes & Nanoobjects, CNRS, Institut Polytechnique Bordeaux, Université Bordeaux

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Stable isotope analysis is commonly used to study diet and residential mobility of past populations. The reliability of isotopic values of the mineral fraction of bones found in archaeological context is regularly questioned because of potential isotopic effects caused by the diagenetic alterations and the chemical treatments of bone apatite.

The aim of this study was to test the validity of two different apatite purification protocols by solid-state Nuclear Magnetic Resonance spectroscopy (NMR) of hydrogen (1H) and carbon (13C) nuclei that consist on: first, elimination of organic matter in bone by sodium hypochlorite treatment during 48h; and second, elimination of exogenous carbonate by two apatite purification methods using 0.1M acetic acid during 4h versus 1M acetic acid during 1h.

NMR 1H and 13C spectra were obtained under magic angle sample spinning (MAS) for: (1) untreated bone, (2) bone after sodium hypochlorite treatment, (3) bone after 0.1M acetic acid treatment, and (4) bone after 1M acetic acid treatment.

This study was performed on 10 archaeological human samples having different states of preservation: 5 from the catacomb of Saints Peter and Marcellinus (1st-3rd century AD, Rome) and 5 from Saint Benedict cemetery (18th century AD, Prague).

Primary results in 13C NMR spectroscopy showed that, despite the sodium hypochlorite treatment, small amounts of organic residues were still present in some samples. The 1H NMR spectroscopy also showed differences in the elimination of exogenous carbonate according to the protocol used. Isotopic effects were established according to concentration and immersion time of acetic acid.

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