Determination of radiocarbon in water by gas or liquid scintillation couting

Two methods of radiocarbon assay in natural water are described: gas counting of synthesized methane in a proportional counter and liquid scintillation counting of synthesized benzene. A method of sample collection in the field is described in which carbonates are precipitated in a special sampler. Highly mineralized water must be treated with acid for carbon dioxide evolution. A comparison of the two counting methods showed the superiority of benzene synthesis and liquid scintillation counting where accuracy better than +- 1% of modern radiocarbon is easy to obtain even for small samples. (author)