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

Abstract

An on-going inter-comparison programme which is focused on assessing and establishing consensus protocols to be applied in the identi®cation, selection and sub-sampling of materials for subsequent 14 C analysis is described. The outcome of the programme will provide a detailed quanti®cation of the uncertainties associated with 14 C measurements including the issues of accuracy and precision. Such projects have become recognised as a fundamental aspect of continuing laboratory quality assurance schemes, providing a mechanism for the harmonisation of measurements and for demonstrating the traceability of results.The design of this study and its rationale are described. In summary, a suite of core samples has been de®ned which will be made available to both AMS and radiometric laboratories. These core materials are representative of routinely dated material and their ages span the full range of the applied 14 C time-scale. Two of the samples are of wood from the German and Irish dendrochronologies, thus providing a direct connection to the master dendrochronological calibration curve. Further samples link this new inter-comparison to past studies.Sample size and precision have been identi®ed as being of paramount importance in de®ning dating con®dence, and so several core samples have been identi®ed for more in-depth study of these practical issues. In addition to the core samples, optional samples have been identi®ed and prepared speci®cally for either AMS and/or radiometric laboratories. For AMS laboratories, these include bone, textile, leather and parchment samples. Participation in the study requires a commitment to a minimum of 10 core analyses, with results to be returned within a year. Ó 2000 Elsevier Science B.V. All rights reserved. 0168-583X/00/$ -see front matter Ó 2000 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 8 -5 8 3 X ( 0 0 ) 0 0 0 9 8 -7

Why do we need 14 C inter-comparisons?: The Glasgow - 14 C inter-comparison series, a reflection over 30 years

“…The next study in the sequence was FIRI (the Fourth International Radiocarbon Intercomparison) which was completed in 2000 (Scott et al, 1997, Bryant et al, 2000, Boaretto et al, 2002. This again was a single stage study, but some samples were provided in duplicate (this fact was blind to participants).…”

Precision and accuracy in applied 14C dating: some findings from the Fourth International Radiocarbon Inter-comparison

“…The fundamental aims and objectives of FIRI [1] reflect a continuing commitment to the issues of accuracy and precision in basic 14 C research and can be simply summarized:…”

“…As in previous inter-comparisons [3], FIRI has focussed on the use of natural materials, and also implemented a two-stage design, with a set of core samples and a set of optional samples [1,7].…”

A Bayesian approach to an interlaboratory comparison

“…Interlaboratory comparisons, in which aliquots of the same samples are measured at different laboratories and the results compared, serve many important purposes [1, 2, 3]. These purposes range from routine quality control to investigating problems arising in challenging new techniques.…”