GAU-Radioanalytical, National Oceanography Centre, Southampton, European Way, Southampton SO14 3ZH, UK.
Anal Chem. 2009 Mar 1;81(5):1901-6. doi: 10.1021/ac802225a.
The routine application of liquid scintillation counting to (41)Ca determination has been hindered by the absence of traceable calibration standards of known (41)Ca activity concentrations. The introduction of the new IRMM (41)Ca mass-spectrometric standards with sufficiently high (41)Ca activities for radiometric detection has partly overcome this although accurate measurement of stable Ca concentrations coupled with precise half-life data are still required to correct the certified (41)Ca:(40)Ca ratios to (41)Ca activity concentrations. In this study, (41)Ca efficiency versus quench curves have been produced using the IRMM standard, and their accuracy validated by comparison with theoretical calculations of (41)Ca efficiencies. Further verification of the technique was achieved through the analysis of (41)Ca in a reactor bioshield core that had been previously investigated for other radionuclide variations. Calcium-41 activity concentrations of up to 25 Bq/g were detected. Accelerator mass spectrometry (AMS) measurements of the same suite of samples showed a very good agreement, providing validation of the procedure. Calcium-41 activity concentrations declined exponentially with distance from the core of the nuclear reactor and correlated well with the predicted neutron flux.
常规应用液体闪烁计数法来测定（41）Ca 一直受到缺乏可溯源的具有已知（41）Ca 活度浓度的校准标准的限制。新的 IRMM（41）Ca 质谱标准的引入部分克服了这一问题，尽管仍然需要准确测量稳定的 Ca 浓度并结合精确的半衰期数据，以将经认证的（41）Ca：（40）Ca 比值校正为（41）Ca 活度浓度。在这项研究中，使用 IRMM 标准生成了（41）Ca 效率与淬灭曲线，并通过与（41）Ca 效率的理论计算进行比较来验证其准确性。通过分析先前已经针对其他放射性核素变化进行过研究的反应堆生物屏蔽核心中的（41）Ca 进一步验证了该技术。检测到高达 25 Bq/g 的（41）Ca 活度浓度。对同一组样品的加速器质谱（AMS）测量结果非常吻合，为该程序提供了验证。从核反应堆核心的距离呈指数下降，与预测的中子通量相关性很好。
