Separation of Nd from geological samples by a single TODGA resin column for high precision Nd isotope analysis as NdO+ by TIMS
Separation of Nd from geological samples by a single TODGA resin column for high precision Nd isotope analysis as NdO+ by TIMS
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通过单个 TODGA 树脂柱从地质样品中分离 Nd，通过 TIMS 进行高精度 Nd 同位素分析（NdO）
DOI：
10.1039/c9ja00200f
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发表时间：
2019-10-01
影响因子：
3.4
通讯作者：
Guo, Jing-Hui
中科院分区：
文献类型：
--
作者：
Chu, Zhu-Yin;Wang, Meng-Jie;Guo, Jing-Hui
用热电离质谱(TIMS)可以将NdO+电离为NdO+的5-10倍。然而，使用NdO+方法时，Ce和Pr必须与Nd2+完全分离，以减少Ce+和Pr+对NdO+的等压干扰(例如(NdO+)-Nd143-O-16上的(PRO+)-Pr-141-O-18)。用以前报道的方法，虽然可以实现完美的Sm-Nd分离，但很难实现有效的Pr-Nd分离。本研究建立了一种基于TODGA树脂的单柱快速分离地质样品中稀土元素的方案(树脂床体积为1毫升，粒径为50-100微米)。包括柱清洗步骤在内的总分离时间约为8h，该方法不仅可以有效地从样品基质中分离出Nd和Sm，而且可以实现Nd与Ce、Pr和Sm的完美分离。Nd和Sm的回收率分别大于90%和95%。此外，由于只涉及单个TODGA柱分离步骤，因此可以获得较低的程序空白(Sm<；5pg；Nd<；10pg)。因此，该方法特别适用于从地质样品中分离出低水平的NdO+，以供TIMS进行同位素分析。最后，对不同柱负荷的BCR-2、BHVO-2、BIR-1a和UB-N等岩石标准物质进行了分析，验证了化学方法的可靠性，分析结果与Nd143/Nd144同位素比值和Sm、Nd值的推荐值吻合较好。
Nd can be ionized to NdO+ about 5-10 fold more efficiently than to Nd+ by thermal ionization mass spectrometry (TIMS). However, with the NdO+ method, Ce and Pr must be separated from Nd as completely as possible to reduce CeO+ and PrO+ isobaric interferences on NdO+ (e.g.(PrO+)-Pr-141-O-18 on (NdO+)-Nd-143-O-16). With previously reported methods, it is difficult to achieve an efficient Pr-Nd separation although a perfect Sm-Nd separation can be achieved. In this study, a rapid, single column scheme for the separation of Nd and Sm from geological samples, based on TODGA resins (1 mL resin bed volume, 50-100 mu m particle size), was developed. The total column separation time, including column cleaning steps, was about 8 h. With this method, not only Nd and Sm could be efficiently separated from the sample matrix, but also a perfect separation of Nd from Ce, Pr and Sm could be obtained. The recovery yield was greater than 90% for Nd and 95% for Sm. Furthermore, since only a single TODGA column separation step was involved, low procedural blanks (Sm < 5 pg; Nd < 10 pg) could be achieved. Therefore, the method is particularly useful for the separation of low levels of Nd from geological samples for isotope analysis as NdO+ by TIMS. Finally, several rock reference materials, including BCR-2, BHVO-2, BIR-1a and UB-N, with different column loads, were analyzed to verify the reliability of the chemical procedure, and the analytical results show good agreement with the recommended values for the Nd-143/Nd-144 isotopic ratios and Sm and Nd concentrations.