This article describes a novel and simple method to measure ultra-trace ²²⁶Ra in river water samples at fg L⁻¹ (mBq L⁻¹) levels as a means for surveying ²²⁶Ra in an unintended contamination in river water. To simplify the procedure, a single column was used for separation and purification; 10 mL of AG 50W-X8 resin was packed into a 10 mL Eppendorf pipette tip, which was used as a separation column. A 500 mL sample solution was loaded, and interfering elements were removed with 80 mL 4 M HCl in 20% ethanol. Subsequently, Ra together with Ba was eluted by 20 mL 5 M HNO₃ prior to SF-ICP-MS analysis; this allows the naturally existing Ba in water samples to be employed as a yield tracer for ²²⁶Ra analysis. Using the medium mode of SF-ICP-MS, the instrumental detection limit of 380 fg L⁻¹ (10 mBq L⁻¹) was obtained. An extremely low method detection limit of 0.46 fg L⁻¹ (0.02 mBq L⁻¹) was achieved with 500-fold pre-concentration. Finally, the developed technique was applied to analyze natural water samples collected from Japanese rivers, in which the ²²⁶Ra concentrations varied in the range of 0.7–49.6 fg L⁻¹ (0.03–1.82 mBq L⁻¹).

本文介绍了一种新颖，简单的方法来测量fg L ^-1（mBq L ^-1）水平的河水样本中的超痕量²²⁶ Ra，作为测量河水中意外污染物²²⁶ Ra的一种方法。为了简化程序，使用一根色谱柱进行分离和纯化。将10 mL的AG 50W-X8树脂装入10 mL的Eppendorf移液器吸头中，用作分离柱。加载500 mL样品溶液，并用20％乙醇中的80 mL 4 M HCl除去干扰元素。随后，在进行SF-ICP-MS分析之前，用20 mL 5 M HNO ₃洗脱Ra和Ba 。这使得水样品中天然存在的Ba可用作²²⁶的产量示踪剂Ra分析。使用SF-ICP-MS的中等模式，仪器检测极限为380 fg L ^-1（10 mBq L ^-1）。预浓缩500倍，可实现0.46 fg L ^-1（0.02 mBq L ^-1）的极低方法检测限。最后，将开发的技术应用于分析从日本河流收集的天然水样，其中²²⁶ Ra浓度在0.7–49.6 fg L ^-1（0.03–1.82 mBq L ^-1）范围内变化。