Initial results from a new, fully automated in situ cosmogenic 14C extraction, purification, and graphitization system at PRIME Lab

Nathaniel Lifton1,2, Jim Wilson3, Alexandria Koester1, Marc Caffee2

1Purdue University, Depth Earth, Atmospheric, and Planetary Sciences, West Lafayette, United States, 2Purdue University, Dept Physics and Astronomy, PRIME Lab, West Lafayette, United States, 3Aeon Laboratories, LLC, Tucson, United States

Extracting in situ cosmogenic ¹⁴C (in situ ¹⁴C) from quartz is a challenging endeavor: minute quantities of ¹⁴C must be extracted and purified from quartz samples while maintaining scrupulous isolation from ubiquitous atmospheric/organic ¹⁴C. These extraction and purification procedures are ripe for automation, as they are time-consuming, and labor-intensive when done manually. Lifton et al. (2015) presented results from the initial automated in situ ¹⁴C extraction and purification systems at the Purdue Rare Isotope Measurement Laboratory (PRIME Lab), reconfigured and retrofitted from our original glass systems at the University of Arizona. While these automated systems increased throughput and reproducibility over our original purely manual systems, they also required manual transfer of sample gas between separate extraction, purification, and (manual) graphitization systems. Ultimately they proved less reliable than hoped, pointing to limitations in the retrofitting of Lifton’s original designs.

We thus recently purchased and installed a customized Carbon Extraction and Graphitization (CEGS) system from Aeon Laboratories, LLC, modified to accommodate our two individually vacuum-pumped tube furnaces. The largely stainless-steel system (except for specific sections requiring glass or fused-quartz components) incorporates more reliable valves and improved actuator designs, as well as a more reliable and efficient liquid nitrogen distribution system. The new system, controlled by a flexible and extensible modular software package written in C# (developed by Aeon), follows a similar procedure to that of Lifton et al. (2015), using a degassed LiBO₂ flux to dissolve the quartz sample in an ultra-high-purity oxygen atmosphere. However, all sections of the new system are connected, so that one can extract all evolved carbon species as CO₂ from a quartz sample, purify and precisely measure the resulting gas yield, and convert the CO₂ to graphite for AMS analysis – all without human intervention. We will present baseline results from the now fully operational system, including process blanks and analyses of established intercomparison materials, for both single-use high-purity aluminum oxide and reusable Pt/10%Rh sample boats.

Lifton, N., Goehring, B., Wilson, J., Kubley, T., and Caffee, M., 2015, Progress in automated extraction and purification of in situ ¹⁴C from quartz: Results from the Purdue in situ ¹⁴C laboratory: Nucl. Inst. Meth. Phys. Res. B, 361, 381–386, doi:10.1016/j.nimb.2015.03.028.


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Date

Nov 08 - 19 2021