Carius tube digestion for low-blank rhenium-osmium analysis
Carius tube digestion for low-blank rhenium-osmium analysis
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DOI：
10.1021/ac00109a036
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发表时间：
1995-07
影响因子：
7.4
通讯作者：
S. Shirey;R. Walker
中科院分区：
文献类型：
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作者：
S. Shirey;R. Walker
在Re-Os同位素分析之前，已开发出一种相对高温的王水氧化消解方法，可用于0.1-5g大小的各种岩石样品，包括硅酸盐、硫化物和金属。反应在240C和加压∼12h下在密封的厚壁Prex管(Carius管)中完成。这种消化技术溶解铂族元素矿物、金属和硫化物，并明显地与硅酸盐充分反应，释放硅酸盐基质中包含的大部分或全部Re和Os。该过程还导致Re和Os的氧化到其最高价态，从而促进了样品Re和Os与添加用于同位素稀释分析的Re和Os的浓缩同位素的完全化学平衡。样品消解平衡后，用常规的硫酸双蒸馏分离Os，再用阴离子交换层析分离Re。对不同地质样品的常规聚四氟乙烯容器消化法和Carius管消化法的比较表明，Carius管消化法既能从大多数基质中释放出更多的O，也是一种更可靠的重复性测量样品同位素组成的方法。
A relatively high-temperature oxidizing digestion using aqua regia has been developed for <0.1-5 g size samples of various types of rocks including silicates, sulfides, and metals prior to Re-Os isotopic analysis. Reactions are accomplished in sealed, thick-walled Pyrex tubes (Carius tubes) at 240 °C and elevated pressures for ∼12 h. This digestion technique dissolves platinum-group element minerals, metals, and sulfides and evidently sufficiently reacts with silicates to release most or all Re and Os contained in a silicate matrix. The procedure also leads to the oxidation of Re and Os to their highest valences and, therefore, promotes the complete chemical equilibration of sample Re and Os with enriched isotopes of Re and Os that are added for isotope dilution analysis. Once sample digestion and equilibration are complete, subsequent Os separation is accomplished by conventional double distillation from sulfuric acid, and Re is separated by anion exchange chromatography. Comparison of conventional Teflon vessel digestions and Carius tube digestions for a diverse suite of geological samples shows that the Carius tube digestion both liberates more Os from most matrices and also is a much more robust method for reproducibly measuring the isotopic composition of a sample.