运用 MC-ICP-MS 测定天然样品的锂同位素组成

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	运用 MC-ICP-MS 测定天然样品的锂同位素组成
	汪齐连
学位类型	硕士
导师	赵志琦
	2006
学位授予单位	中国科学院大学
学位授予地点	中国科学院地球化学研究所
关键词	锂同位素提纯最佳实验条件 mc-icp-ms 低含量样品
摘要	自然界锂同位素分馏强烈，这使得它在很多方面都得到了应用，如地球化学、天体化学和核工业等。所有这些领域都要求精确地测定6 Li/7 Li的比值。但由于锂是微量元素，而且在测试过程中还存在明显的干扰，因此在进行锂同位素比值测定之前必须对样品进行前处理，将锂分离、富集、提纯。本文以锂元素标准样品和钾、钠、钙、镁元素标准样品的混合溶液为主要研究对象，采用阳离子交换树脂AG-50W-X8 来分离富集锂，探索在不同淋洗介质（包括盐酸、硝酸以及与甲醇、乙醇的混合）条件下锂分离纯化的最佳介质条件。初步得出以下结论： 1、本次研究建立了相对简单、高效的锂同位素分离方法。用单一的柱子分离、提纯样品锂；用低浓度的盐酸（0.15M HCl）直接作为淋洗介质，操作过程简单。 2、对锂同位素比值测定产生影响的潜在因素，如基体效应、回收率、流程空白等进行了实验研究，证实这些影响因素对于本次研究所建立的方法来说都是可以忽略不计的。 3、用 MC-ICP-MS 测定锂同位素组成，分析结果的准确度和精度与现阶段报道数据相同。测定海水的锂同位素组成（+31.6±1.0‰，2σ）与前人测定结果的平均值（+31.2‰）接近，与 Tomoscak 等（+31.8±1.9‰，2σ）的分析值相近。天然样品分析测定的误差为 0.8‰（2σ），与 TIMS 的测定结果相似。 4、该方法也适用于低锂含量的样品。我们分离并测定了部分海水、岩石、土壤、河水等样品的锂同位素组成，样品含量在 0.064µg/g 和 132 µg/g 之间，说明该方法也同样适用于低含量地质样品的分析测定。
其他摘要	The relative large lithium isotopic fractionation in natural samples has useful application in the fields of geochemistry, cosmo-chemistry and nuclear chemistry. All these fields require precise measurement of the 7 Li/6 Li ratio. There are visible interferers in the process of measurement due to trace element, so we must prepare the natural samples before determination of lithium isotopic composition, including separation, enrichment and purification. In this thesis, the solution of Chinese reference materials including lithium, potassium, calcium, sodium, magnesium, was used to evaluate analytical methods applied. Lithium was enriched in different eluents (hydrochloric acid, nitric acid and mixture with ethanol or methanol) by cation exchange resin AG 50W-X8, and the optional experimental conditions were studied. Some main conclusions are listed as follows: 1、Setting up a rapid and valid method which separate lithium from other elements by one column. This method only uses 0.15M HCl as eluent, and operation is very simple. 2、The influence of potential sources of error for acquisition of lithium isotopic data introduced during the separation, such as matrix effects and isotopic fractionation due to incomplete recovery, were examined by using artificial mixed solution. The examinations demonstrated that our protocol suffered from negligible isotopic fractionation. 3、MC-ICP-MS was applied to lithium isotopic measurements. Based on multiple duplicate and replicate measurements, the precision of this method is conservatively estimated to be 0.8‰ (2σ), which is similar to the precision of other method by TIMS. The δ7 Li value determined for sea water is +31.8‰, which agree well with those of previously reported datum. 4、This method can be applied to some samples having low concentration of lithium. We determined lithium isotope of some seawater, rock and soil samples in which concentration of lithium rang from 0.064µg/g to 132µg/g，so the method is fit for low lithium reservoirs.
语种	中文
文献类型	学位论文
条目标识符	http://ir.gyig.ac.cn/handle/42920512-1/10788
专题	研究生
推荐引用方式 GB/T 7714	汪齐连. 运用 MC-ICP-MS 测定天然样品的锂同位素组成[D]. 中国科学院地球化学研究所. 中国科学院大学,2006.

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