T02_P26

Using XAD resin to remove synthetic contamination from archaeological bone prior to radiocarbon dating

van der Sluis L^1,2,  Zazzo A¹, Thil F³, Pétillon J⁴

¹Archéozoologie, Archéobotanique, Sociétés, Pratiques et Environnements (AASPE) UMR 7209, Muséum national d’Histoire naturelle, CNRS, Paris, France, ²Department Of Evolutionary Anthrpology, University of Vienna, Vienna, Austria, ³Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL UMR 8212, CEA-CNRS-UVSQ, Université Paris Saclay, F-91198 , Gif-sur-Yvette, France, ⁴Travaux et Recherche Archéologiques sur les Cultures, les Espaces et les Sociétés (TRACES) UMR 5608, Toulouse,  France

Extraction protocols for radiocarbon dating bone collagen samples are continuously being tested and improved. Contamination can originate from the burial environment as well as post-excavation treatments, involving conservation treatments using synthetic consolidants. While most contamination can be removed using the ABA method, this is not the case for cross-linked contamination. The most suitable method to remove contamination from especially small bone samples seems to be the XAD method.

The XAD protocol was implemented at the MNHN radiocarbon laboratory and tested using known age bone samples and a Palaeolithic bone sample that had been consolidated and produced an anomalous peak in the FTIR-ATR spectra at 1725 cm^-1.

To test the functionality of the XAD resin, samples of known age were consolidated with shellac or Paraloid and artificially aged in a climate chamber for a month. Samples were then treated with or without the XAD resin and radiocarbon dated. The Hollis bone blank showed that XAD resin was able to remove young carbon from shellac, which was not the case for the ABA-only method. Results from VIRI I were more variable and VIRI F was possibly too young to show the effects of the consolidants. Four radiocarbon dates on the Palaeolithic bone after XAD treatment are statistically the same, while a sample without XAD treatment was significantly older, suggesting that the contaminant was not fully removed by the classical ABA treatment. This study demonstrates the interest of the XAD treatment to clean heritage bone samples stored in museums prior to geochemical analyses.