Rapid Sample Preparation for ¹⁴C Dating by Using Direct Reaction of Carbonized Sample and Lithium Metal

Abstract

In¹⁴Cdating by LSC system, benzene is usually synthesized from collected samples via several chemical reactions such as pretreatment, carbonization, combustion, carbonating, carbide production, acetylene generation and polymerization. Since a great deal of efforts is required to the sample preparation, we proposed an another rapid process where the carbonized samples reacted to melted lithium metal directly to produce lithium carbide.
Although the yield generating acetylene gas from carbonized samples was low, 52.5±1.5% on average, the yield synthesizing benzene from acetylene was 90% or more in the successive process. Some impurity atoms contained in carbonized samples deteriorate apparently the yield generating acetylene but they did not influence the yield synthesizing benzene from acetylene. This shows that combustion is not indispensable process in¹⁴Csample preparation.
¹⁴Cages for the samples prepared by the proposed method were agreed to those for the same samples prepared by the conventional method within the age variation corresponding to the statistical error of 1σ.Therefore the fractionation effect of carbon isotopes may be low, if any, in the proposed process. Since this method does not contain combustion and the following carbonating process, the sample preparation is fairly shortened.