Zinc reduction as an alternative method for AMS radiocarbon dating: Process optimization at CIRCE

The pretreatment of samples for radiocarbon measurements, transforming a variety of materials into graphite solid targets, represents a critical point in the accelerator mass spectrometry (AMS) procedure. We describe the new, state-of-the-art CIRCE AMS preparation laboratory, particularly the setup and optimization of an alternative method, the zinc reduction method, for graphite target production, compared to the more common hydrogen reduction method. Measured 14C values on standard and blank samples reduced via zinc reaction revealed mean background levels, accuracy, and sensitivity comparable to those obtained by our conventional hydrogen reaction lines. Zinc line reduction at the CIRCE laboratory represents an effective and powerful alternative to the conventional hydrogen reduction, ensuring higher sample throughput with lower costs at a comparable performance level. © 2008 by the Arizona Board of Regents on behalf of the University of Arizona.