The current performance of the in situ 14C extraction line at ETH

We present the new 14 C extraction line at ETH Zurich. This system is designed to extract in situ -produced cosmogenic 14 C from terrestrial quartz samples, and to obtain pure CO 2 gas for analysis with a gas ion source Accelerator Mass Spectrometry (AMS) system. Samples are degassed at 1550–1600 °C without the use of a fluxing agent. Gas purification is achieved by a series of cryogenic traps and passage through hot Ag and Cu wool/mesh. Graphitization and, thus, sample dilution is not required. Tests to determine the CO 2 recovery after gas extraction and cleaning yielded consistently good recovery rates of >99.8% ( n = 7). The 14 C blank contribution from the all-metal tubing system is negligible. Our preliminary procedural blank estimate – deriving mostly from the hot extraction furnace – is 5 14 C atoms. Extraction tests on two quartz samples by stepped-heating show a quantitative separation of atmospheric 14 C at ≤500 °C from the in situ component above 1200 °C. Based on these data, we estimate to achieve a complete 14 C extraction from a quartz sample.