Sample requirements and design of an inter-laboratory trial for radiocarbon laboratories

An on-going inter-comparison programme which is focused on assessing and es tablishing consensus protocols to be applied in the identification, selecti on and sub-sampling of materials for subsequent C-14 analysis is described. The outcome of the programme will provide a detailed quantification of the uncertainties associated with C-14 measurements including the issues of ac curacy and precision. Such projects have become recognised as a fundamental aspect of continuing laboratory quality assurance schemes, providing a mec hanism for the harmonisation of measurements and for demonstrating the trac eability of results. The design of this study and its rationale are described. In summary, a sui te of core samples has been defined which will be made available to both AM S and radiometric laboratories. These core materials are representative of routinely dated material and their ages span the full range of the applied C-14 time-scale. Two of the samples are of wood from the German and Irish d endrochronologies, thus providing a direct connection to the master dendroc hronological calibration curve. Further samples link this new inter-compari son to past studies. Sample size and precision have been identified as being of paramount import ance in defining dating confidence, and so several core samples have been i dentified for more in-depth study of these practical issues. In addition to the core samples, optional samples have been identified and prepared speci fically for either AMS and/or radiometric laboratories. For AMS laboratorie s, these include bone, textile, leather and parchment samples. Participatio n in the study requires a commitment to a minimum of 10 core analyses, with results to be returned within a year. (C) 2000 Elsevier Science B.V. All r ights reserved.