Method to Determine 226Ra in Small Sediment Samples by Ultralow Background Liquid Scintillation

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• 作者：Joan-Albert Sanchez-Cabeza ; Laval Liong Wee Kwong ; Maria Betti
• 刊名：Analytical Chemistry
• 出版年：2010
• 出版时间：August 15, 2010
• 年：2010
• 卷：82
• 期：16
• 页码：6847-6853
• 全文大小：260K
• 年卷期：v.82,no.16(August 15, 2010)
• ISSN：1520-6882

文摘

²¹⁰Pb dating of sediment cores is a widely used tool to reconstruct ecosystem evolution and historical pollution during the last century. Although ²²⁶Ra can be determined by γ spectrometry, this method shows severe limitations which are, among others, sample size requirements and counting times. In this work, we propose a new strategy based on the analysis of ²¹⁰Pb through ²¹⁰Po in equilibrium by α spectrometry, followed by the determination of ²²⁶Ra (base or supported ²¹⁰Pb) without any further chemical purification by liquid scintillation and with a higher sample throughput. Although γ spectrometry might still be required to determine ¹³⁷Cs as an independent tracer, the effort can then be focused only on those sections dated around 1963, when maximum activities are expected. In this work, we optimized the counting conditions, calibrated the system for changing quenching, and described the new method to determine ²²⁶Ra in small sediment samples, after ²¹⁰Po determination, allowing a more precise determination of excess ²¹⁰Pb (²¹⁰Pb_ex). The method was validated with reference materials IAEA-384, IAEA-385, and IAEA-313.