T03_P09

One-pot processing of tree-ring samples for ¹⁴C analysis on cellulose

PHOUYBANHDYT B^1,4, DU BOISGUEHENEUC D^1,2,4, DAUX V¹, NOURY C¹, PIERRE M¹, STIEVENARD M¹, THIL F¹, HATTÉ C^1,3

¹Laboratoire des Sciences du Climat et de l'Environnement, Gif-sur-Yvette, France, ²Archéozoologie, Archéobotanique : Sociétés, Pratiques et Environnements, Paris, France, ³Silesian University of Technology, Gliwice, Poland, ⁴These authors contributed equally to this work, ,

Analyzing the radiocarbon fraction in tree rings is fundamental to the radiocarbon method in order to calibrate ¹⁴C years into calendar years. The increasing interest in measuring ¹⁴C at annual resolution implies an even larger number of tree-ring samples to be pretreated. And this, focusing on latewood cellulose to ensure that the carbon originates from only one year and has not been exchanged since formation.

To put ourselves on a battle footing for several projects we are involved in and that require large series of measurements, we confronted our protocol to others available in literature. We finally settled on an adaptation of the protocol used for stable isotopes measurements at LSCE that derives from the original protocol of Leavitt and Danzer (1993). We also considered some advice of Southon and Magana (2010) and added our own “touch”.

The chemistry is done in a 1.5 L Erlenmeyer flask in which the samples and standards are pooled, packed in an individual Teflon bag. The protocol is divided into three main steps: removal of water-soluble compounds, removal of lignin by a two-step oxidative delignification and removal of hemicellulose by alkaline extraction.

Our protocol allows the preparation of up to fifteen samples and five standards at the same time, without cross-contamination, saving thus time in handling and reducing chemical consumption. We present here the results we obtained on blanks and reference materials of different ages. They clearly indicate that this protocol allows to obtain results as accurate as with individual treatments.