Target preparation for radiocarbon dating by tandem accelerator mass spectrometry

Techniques of sample preparation of milligram-sized samples for ¹⁴C determinations by tandem accelerator mass spectrometry are reported. Precisions of better than ±2% in measurement of ¹⁴C/¹³C on a single target, an iron-carbon bead containing about a milligram of carbon can be achieved in about one hour's actual measurement time on the target. Standard materials with known ¹⁴C/¹³C ratios are measured in the same way. High precision data can be achieved by much longer counting times up to 4 h, often on several targets. Higher count rates could be achieved by use of graphite targets and preliminary studies of graphitization of small samples are also reported.