Abstract：
BACKGROUND: Trace metals such as iron, nickel, copper, zinc, and cadmium (Fe, Ni, Cu, Zn, and Cd) are essential micronutrients (and sometimes toxins) for phytoplankton, and the analysis of trace-metal stable isotopes in seawater is a valuable tool for exploring the biogeochemical cycling of these elements in the ocean. However, the complex and often time-consuming chromatography process required to purify these elements from seawater has limited the number of trace-metal isotope samples which can be easily processed in biogeochemical studies. To facilitate the trace-metal stable isotope analysis, here, we describe a new rapid procedure that utilizes automated chromatography for extracting and purifying Ni and Cu from seawater for isotope analysis using a prepFAST-MC™ system (Elemental Scientific Inc.).
RESULTS: We have tested the matrix removal effectiveness, recoveries, and procedural blanks of the new purification procedure with satisfactory results. A nearly complete recovery of Ni and a quantitative recovery of Cu are achieved. The total procedural blanks are 0.33 ± 0.24 ng for Ni and 0.42 ± 0.18 ng for Cu, which is negligible for natural seawater samples. The new procedure cleanly separates Ni and Cu from key seawater matrix elements that may cause interferences during mass spectrometry analysis. When the new procedure was used to purify seawater samples for Ni and Cu stable isotope analysis by multi-collector ICP-MS, we achieved an overall uncertainty of 0.07 ‰ for δ60Ni and 0.09 ‰ for δ65Cu (2 SD). The new purification procedure was also tested using natural seawater samples from the South Pacific, for comparison of δ60Ni and δ65Cu achieved in the same samples purified by traditional hand columns. Both methods produced similar results, and the results from both methods are consistent with analyses of δ60Ni and δ65Cu from other ocean locations as reported by other laboratories.
CONCLUSIONS: This study presents a new rapid procedure for seawater stable-metal isotope analysis by automating the chromatography step. We anticipate that the automated chromatography described here will facilitate the rapid and accurate analysis of seawater δ60Ni and δ65Cu in future studies, and may be adapted in the future to automate chromatographic purification of Fe, Zn, and Cd isotopes from seawater.
RESULTS: We have tested the matrix removal effectiveness, recoveries, and procedural blanks of the new purification procedure with satisfactory results. A nearly complete recovery of Ni and a quantitative recovery of Cu are achieved. The total procedural blanks are 0.33 ± 0.24 ng for Ni and 0.42 ± 0.18 ng for Cu, which is negligible for natural seawater samples. The new procedure cleanly separates Ni and Cu from key seawater matrix elements that may cause interferences during mass spectrometry analysis. When the new procedure was used to purify seawater samples for Ni and Cu stable isotope analysis by multi-collector ICP-MS, we achieved an overall uncertainty of 0.07 ‰ for δ60Ni and 0.09 ‰ for δ65Cu (2 SD). The new purification procedure was also tested using natural seawater samples from the South Pacific, for comparison of δ60Ni and δ65Cu achieved in the same samples purified by traditional hand columns. Both methods produced similar results, and the results from both methods are consistent with analyses of δ60Ni and δ65Cu from other ocean locations as reported by other laboratories.
CONCLUSIONS: This study presents a new rapid procedure for seawater stable-metal isotope analysis by automating the chromatography step. We anticipate that the automated chromatography described here will facilitate the rapid and accurate analysis of seawater δ60Ni and δ65Cu in future studies, and may be adapted in the future to automate chromatographic purification of Fe, Zn, and Cd isotopes from seawater.
摘要：
背景：痕量金属，如铁，镍,铜，锌，和镉(铁，Ni,Cu,Zn,和Cd）是浮游植物必需的微量营养素（有时是毒素），海水中痕量金属稳定同位素的分析是探索海洋中这些元素的生物地球化学循环的宝贵工具。然而,从海水中纯化这些元素所需的复杂且通常耗时的色谱过程限制了痕量金属同位素样品的数量，这些样品可以在生物地球化学研究中轻松处理。为了便于痕量金属稳定同位素分析，在这里，我们描述了一种新的快速程序，该程序利用自动色谱从海水中提取和纯化Ni和Cu，以使用preFAST-MC™系统（ElementalScientificInc.）进行同位素分析。
结果：我们已经测试了基质去除效果，回收，和新纯化程序的程序空白，结果令人满意。实现了Ni的几乎完全回收和Cu的定量回收。总程序空白为Ni为0.33±0.24ng，Cu为0.42±0.18ng，这对于天然海水样品来说是微不足道的。新程序从可能在质谱分析过程中引起干扰的关键海水基质元素中干净地分离Ni和Cu。当新程序用于净化海水样品以通过多收集器ICP-MS进行Ni和Cu稳定同位素分析时，我们对δ60Ni的总体不确定度为0.07‰，对δ65Cu的总体不确定度为0.09‰（2SD）。还使用来自南太平洋的天然海水样品测试了新的净化程序，用于比较在通过传统手柱纯化的相同样品中获得的δ60Ni和δ65Cu。两种方法都产生了相似的结果，两种方法的结果与其他实验室报告的其他海洋位置的δ60Ni和δ65Cu的分析一致。
结论：本研究通过自动化色谱步骤，为海水稳定金属同位素分析提供了一种新的快速程序。我们预计，这里描述的自动色谱将有助于在未来的研究中快速准确地分析海水δ60Ni和δ65Cu，并可能在未来适用于自动化的Fe色谱纯化，Zn,和海水中的Cd同位素。
结果：我们已经测试了基质去除效果，回收，和新纯化程序的程序空白，结果令人满意。实现了Ni的几乎完全回收和Cu的定量回收。总程序空白为Ni为0.33±0.24ng，Cu为0.42±0.18ng，这对于天然海水样品来说是微不足道的。新程序从可能在质谱分析过程中引起干扰的关键海水基质元素中干净地分离Ni和Cu。当新程序用于净化海水样品以通过多收集器ICP-MS进行Ni和Cu稳定同位素分析时，我们对δ60Ni的总体不确定度为0.07‰，对δ65Cu的总体不确定度为0.09‰（2SD）。还使用来自南太平洋的天然海水样品测试了新的净化程序，用于比较在通过传统手柱纯化的相同样品中获得的δ60Ni和δ65Cu。两种方法都产生了相似的结果，两种方法的结果与其他实验室报告的其他海洋位置的δ60Ni和δ65Cu的分析一致。
结论：本研究通过自动化色谱步骤，为海水稳定金属同位素分析提供了一种新的快速程序。我们预计，这里描述的自动色谱将有助于在未来的研究中快速准确地分析海水δ60Ni和δ65Cu，并可能在未来适用于自动化的Fe色谱纯化，Zn,和海水中的Cd同位素。
