Precise measurement of chlorine stable isotopic ratios by thermal ionization mass spectrometry
Precise measurement of chlorine stable isotopic ratios by thermal ionization mass spectrometry
复制标题
通过热电离质谱法精确测量氯稳定同位素比
DOI：
10.2343/geochemj.35.89
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发表时间：
2001
影响因子：
0.8
通讯作者：
T. Gamo
中科院分区：
文献类型：
--
作者：
M. Numata;N. Nakamura;N. Nakamura;T. Gamo
本文研究了一种改进的Cs_2Cl ~+热电离质谱氯同位素分析方法，以精确测定少量样品的~（37）Cl/~（35）Cl同位素比值。有机和无机样品中的氯以AgCl形式回收，用金属Mg和Cs型离子交换树脂转化为CsCl。将CsCl（含有2 μg Cl）与石墨粉末一起负载在Ta细丝上。使用Cs2 Cl+离子用多个法拉第杯（静态模式）进行37 Cl/35 Cl比率测量，每次运行80-100分钟。海水和实验室标准品（CsCl试剂）的重复分析得到300-400个比值的运行内精密度为0.1-0.2‰（2σm），外部精密度为0.1-0.2‰（1σSD）。该方法已在多种化学试剂上进行了测试，包括金属氯化物、盐酸和氯化有机溶剂。结果发现，人造氯化合物的37 Cl/35 Cl比率（相对于标准平均海洋氯化物的总范围为-5至+3‰）因制造工艺而异。我们建议，在这项工作中建立的高灵敏度和精度的技术将使我们能够检测到少量的天然样品，如陆地材料（矿物/岩石，沉积物，地下水等，以及环境材料），陨石和其他行星材料中的氯的同位素变化。
An improved method for chlorine isotopic analysis by thermal ionization mass spectrometry of Cs2Cl+ has been investigated for precise measurement of 37Cl/35Cl isotopic ratios for small amount of samples. Chlorine in organic and inorganic samples was recovered as AgCl and converted to CsCl with metallic Mg and Cs-form ion exchange resin. The CsCl (containing 2 μg of Cl) was loaded on a Ta filament together with graphite powder. The 37Cl/35Cl ratio measurement was carried out using Cs2Cl+ ions with multi Faraday cup (static mode) for 80–100 min each single run. Replicate analysis of ocean water and laboratory standard (CsCl reagent) yield the in-run precision of 0.1–0.2‰ (2σm) for 300–400 ratios and external precision of 0.1–0.2‰ (1σSD). This method has been tested on a variety of chemical reagents including metal chlorides, hydrochloric acid and chlorinated organic solvents. It was found that the artificial chlorine compound show large variations of 37Cl/35Cl ratio (total ranges from −5 to +3‰ relative to standard mean ocean chloride) depending upon manufacturing processes. We suggest that the high sensitivity and precision technique established in this work would allow us to detect small isotopic variations of chlorine in small amounts of natural samples such as terrestrial materials (minerals/rocks, sediments, groundwater, etc, as well as environmental materials), meteorites and other planetary materials.