The precise determination of radium-226 (²²⁶Ra) in environmental samples is challenging due to its low concentration. Seawater typically contains between 0.03 and 0.1 fg g^{−1 226}Ra. Thus, this work addresses the need for an easy and precise methodology for ²²⁶Ra determination in seawater that may be applied routinely to a large number of samples. For this reason, a new analytical approach has been developed for the quantification of ²²⁶Ra in seawater via inductively coupled plasma mass spectrometry (ICP-MS). Analysis by single collector sector-field ICP-MS was shown to be convenient and reliable for this purpose once potential molecular interferences were excluded by a combination of chemical separation and intermediate mass resolution analysis. The proposed method allows purification of Ra from the sample matrix based on preconcentration by MnO₂ precipitation, followed by two-column separation using a cation exchange resin and an extraction chromatographic resin. The method can be applied to acidified and unacidified seawater samples. The recovery efficiency for Ra ranged between 90% and 99.8%, with precision of 5%, accuracy of 95.7% to 99.9%, and a detection limit of 0.033 fg g⁻¹ (referring to the original concentration of seawater). The method has been applied to measure ²²⁶Ra concentrations from the North Sea and validated by analyzing samples from the central Arctic (GEOTRACES GN04). Samples from a crossover station (from GEOTRACES GN04 and GEOTRACES GN01 research cruises) were analyzed using alternative methods, and our results are in good agreement with published values.

中文翻译：

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单收集器扇形场ICP-MS同位素稀释法分析1升海水中的226Ra

由于其浓度低，因此准确测定环境样品中的镭226（²²⁶ Ra）具有挑战性。海水通常含有0.03至0.1 fg g ^{-1 226} Ra。因此，这项工作满足了一种简便，精确的方法来确定海水中²²⁶ Ra的需要，该方法可以常规应用于大量样品。因此，开发了一种新的分析方法来定量分析²²⁶通过电感耦合等离子体质谱法（ICP-MS）测定海水中的Ra。一旦通过化学分离和中等质量分辨率分析相结合排除了潜在的分子干扰，就证明了通过单收集器扇形场ICP-MS进行的分析既方便又可靠。所提出的方法允许基于通过MnO ₂沉淀进行的预浓缩从样品基质中纯化Ra ，然后使用阳离子交换树脂和萃取色谱树脂进行两柱分离。该方法可用于酸化和未酸化的海水样品。Ra的回收率在90％至99.8％之间，精度为5％，精度为95.7％至99.9％，检出限为0.033 fg g ^-1（指的是海水的原始浓度）。该方法已应用于测量北海的²²⁶ Ra浓度，并通过分析北极中心地区（GEOTRACES GN04）的样品进行了验证。使用替代方法分析了交叉站（来自GEOTRACES GN04和GEOTRACES GN01研究巡航）的样本，我们的结果与已发表的值非常吻合。