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Research Center of Radioisotopes at University of Osaka Prefecture Radiocarbon Dates I

Published online by Cambridge University Press:  18 July 2016

Setsuko Shibata ,
Eiko Kawano  and
Takeshige Nakabayashi
Setsuko Shibata
Affiliation:
Research Center of Radioisotopes, Research Institute for Advanced Science and Technology, University of Osaka Prefecture, 1–2, Gakuen-cho, Sakai, Osaka, Japan
Eiko Kawano
Affiliation:
Research Center of Radioisotopes, Research Institute for Advanced Science and Technology, University of Osaka Prefecture, 1–2, Gakuen-cho, Sakai, Osaka, Japan
Takeshige Nakabayashi
Affiliation:
Research Center of Radioisotopes, Research Institute for Advanced Science and Technology, University of Osaka Prefecture, 1–2, Gakuen-cho, Sakai, Osaka, Japan
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The radiocarbon dating laboratory has been in operation since 1984 at the Radiation Center of Osaka Prefecture (OR), predecessor of the Research Center of Radioisotopes, University of Osaka Prefecture. We use liquid scintillation counting (LSC), following sample conversion to methanol through combustion and LiAlH4 reduction. This method was developed by Yamada et al. (Yamada, Higashimura and Shidei 1966; Yamada and Kobashigawa 1986). In cooperation with Yamada, we somewhat modified their procedure: 1) sample charcoal is burned at 700° in the presence of CuO needles and Sulfix grains to remove sulfur and halogen compounds produced during the combustion; 2) the combustion is carried out by using N2-O2 mixed gas of minimized O2 content and stopped when a small amount of the charcoal still remains unchanged, because precise investigation of methanol preparation revealed that O2 gas stimulates byproduct formation during LiAlH4 reduction (Shibata et al. 1985; Shibata et al. 1993). Usually, methanol is prepared directly from sample charcoal in a reaction apparatus (“direct method”). When the sample quantity is insufficient, generated CO2 is isolated as CaCO3 and diluted with inactive commercial CaCO3 if necessary (< 40 g of CaCO3 yield). Then CaCO3 is hydrolyzed with HCl to CO2 for methanol preparation in the usual way (“separate method”). We use standard oxalic acid SRM 4990C (HOxII) for determination of modern 14C (Stuiver 1983). The acid is oxidized to CO2 using the wet method of Valastro, Land and Valera (1977) followed by methanol preparation in the same manner as for unknown samples.

Type
Date Lists
Information
Radiocarbon , Volume 39 , Issue 1 , 1997 , pp. 79 - 87
Copyright
Copyright © The American Journal of Science 

References

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