Problems and methods of dating low-activity samples by liquid scintillation counting

The important problem of contamination of old samples by younger 14C necessitates treatment of organic and carbonate samples to ensure more complete removal of contaminating carbon. Here we present studies of chemical procedures for the liquid scintillation method of 14C dating undertaken since 1960 in the former USSR. We discuss new procedures such as lithium carbide synthesis from charred organic samples and benzene synthesis on a catalyst, as well as memory effect in the carbide synthesis procedure and characteristics of two homemade counters.