Browsing Radiocarbon, Volume 43, Number 2A (2001 by Authors
Automatic AMS Sample Combustion and CO2 CollectionAerts-Bijma, A. T.; van der Plicht, J.; Meijer, H. A. J. (Department of Geosciences, The University of Arizona, 2001-01-01)In Groningen, all organic samples for accelerator mass spectrometry (AMS) are combusted in an automatic Elemental Analyzer, coupled to an Isotope Ratio Mass Spectrometer and Cryogenic Trapping System. The Gas Chromatographic (GC) column, part of the Elemental Analyzer system, appeared to be the main cause for memory effects. Therefore we modified the Elemental Analyzer, such that the trapped CO2 no longer passed the GC column. Our system modification reduced the memory effect significantly, as shown by lower radiocarbon concentration values for anthracite backgrounds, and a much smaller spread in these values. Our modified system can perform up to 40 combustions unattended in about 6 hr.
Dating of Cremated BonesLanting, J. N.; Aerts-Bijma, A. T.; van der Plicht, J. (Department of Geosciences, The University of Arizona, 2001-01-01)When dating unburnt bone, bone collagen, the organic fraction of the bone, is used. Collagen does not survive the heat of the cremation pyre, so dating of cremated bone has been considered impossible. Structural carbonate in the mineral fraction of the bone, however, survives the cremation process. We developed a method of dating cremated bone by accelerator mass spectrometry (AMS), using this carbonate fraction. Here we present results for a variety of prehistoric sites and ages, showing a remarkable success rate for this method.
Is Comparability of 14C Dates an Issue?: A Status Report on the Fourth International Radiocarbon IntercomparisonBryant, C.; Carmi, I.; Cook, G. T.; Gulliksen, S.; Harkness, D. D.; Heinemeier, J.; McGee, E.; Naysmith, P.; Possnert, G.; Scott, E. M.; et al. (Department of Geosciences, The University of Arizona, 2001-01-01)For more than 15 years, the radiocarbon community has participated in a series of laboratory intercomparisons in response to the issue of comparability of measurements as perceived within the wider user communities (Scott et al. 1990; Rozanski et al. 1992; Gulliksen and Scott 1995; Scott et al. 1997). In this report, we provide an update on the current 14C laboratory intercomparison and reflect on future issues linked to the laboratory intercomparison program, not least those resulting from a significant growth in the number of accelerator mass spectrometry (AMS) facilities providing routine dating of small samples (milligram size).