An approach for optimizing in situ cosmogenic Be-10 sample preparation

摘要

Optimizing sample preparation for the isotopic measurement of Be-10 extracted from quartz mineral separates has a direct positive effect on the accuracy and precision of isotopic analysis. Here, we demonstrate the value of tracing Be throughout the extraction process (both after dissolution and after processing), producing pure Be (by optimizing ion exchange chromatography methods and quantifying quartz mineral separate and final Be fraction purity), and minimizing backgrounds (through reducing both laboratory process blanks and B-10 isobaric interference). These optimization strategies increase the amount of Be-10 available for analysis during accelerator mass spectrometry (AMS), while simultaneously decreasing interference and contamination, and ensuring that sample performance matches standard performance during analysis. After optimization of our laboratory's extraction methodology, Be-9(3+) ion beam currents measured during AMS analysis, a metric for sample purity and Be yield through the extraction process, matched the Be-9(3+) beam currents of AMS standards analyzed at the same time considering nearly 800 samples. Optimization of laboratory procedures leads to purer samples that perform better, more consistently, and more similarly to standards during AMS analysis, allowing for improved precision and accuracy of measurements used for dating and quantification of Earth surface processes. (C) 2016 Elsevier B.V. All rights reserved.