Assessment of oxygen plasma ashing as a pre-treatment for radiocarbon dating

Abstract

This study investigates the potential of low-temperature oxygen plasma ashing as a technique for decontaminating charcoal and wood samples prior to radiocarbon dating. Plasma ashing is demonstrated to be rapid, controllable and surface-specific. Different organic materials clearly ash at different rates, however, the ability of plasma ashing to selectively ash different organic components is limited in heterogeneous sample matrices. This is because oxidation is confined to the immediate sample surface. Comparison of radiocarbon dates obtained from identical aliquots of contaminated ancient charcoal pre-treated by acid–base–acid (ABA), acid–base-oxidation-stepped combustion (ABOx-SC) and plasma ashing suggests that the technique performs as well as the ABA pre-treatment but does not remove as much contamination as the ABOx-SC technique. Plasma ashing may be particularly useful in cases where sample size is limiting.