Laboratory intercomparison of Pleistocene bone radiocarbon dating protocols

Since its invention in the late 1940’s, radiocarbon dating has become an important tool for absolute dating. A prerequisite for the acceptance of this method is consistency between, and compatibility of, radiocarbon dates from different laboratories. To meet these requirements, international laboratory intercomparison studies with different sample materials are frequently performed (e.g. TIRI, FIRI, VIRI and, most recently, SIRI). Intercomparison is especially relevant and difficult for samples close to the dating limit of ~50 kBP, not least for bone samples. A radiocarbon intercomparison study between the Leibniz-Laboratory in Kiel (Germany), the Centre for Isotope Research (CIO) in Groningen (The Netherlands), and the Oxford Radiocarbon Accelerator Unit (ORAU; United Kingdom) was performed on three Pleistocene (MIS3) mammal bone samples from the Brick Quarry site Coenen (BQC) in Germany. The comparison of individually prepared and measured bone collagen radiocarbon activities, results from shared collagen measurements, and respective background signatures and correction points to the latter as the main factor responsible for observed differences in final given radiocarbon estimates.