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以不同浓度Li元素标准样品和K、Ca、Na、Mg、Fe单元素标准样品的混合溶液为研究对象,采用3根阳离子交换树脂(AG50 W-X8,200~400目)填充的聚丙烯交换柱和石英交换柱对Li进行分离富集,淋洗液分别为2.8 mol/L HCl、0.15 mol/L HCl以及0.5 mol/L HCl 30%乙醇,淋洗液体积小,仅为38 mL。分离回收率高,均大于97.6%。国际标样AGV-2(相对于IRMM-016)、BHVO-2(相对于IRMM-016)和IRMM-016(相对于L-SVEC)的δ7Li值分别为(5.13±0.94)‰(2σ,n=10)、(4.08±0.60)‰(2σ,n=4)和(0.038±0.73)‰(2σ,n=10),与前人分析结果吻合,分析精度与国际同类实验室水平相当。并对比了马里兰大学同位素实验室和笔者实验室对同种岩石矿物样品的分析结果,在误差范围内具有很好的一致性。此外,对美国地质调查局提供的准标样NKT-1霞石岩(相对于IRMM-016)给出了定值,δ7Li值为(8.71±0.46)‰(2σ,n=4)。因此,本方法可用于测定天然样品的Li同位素组成。
The mixed solution of standard samples with different concentrations of Li and K, Ca, Na, Mg and Fe was used as the research object. The polypropylene filled with three cation exchange resins (AG50 W-X8 and 200-400 meshes) The columns were separated and enriched with quartz and the quartz exchange column. The eluents were 2.8 mol / L HCl, 0.15 mol / L HCl and 0.5 mol / L HCl 30% ethanol, respectively. The eluent volume was only 38 mL. High separation and recovery, both greater than 97.6%. The δ7Li values for the international standard samples AGV-2 (vs. IRMM-016), BHVO-2 (vs. IRMM-016) and IRMM-016 (vs. L-SVEC) were (5.13 ± 0.94) ‰ (4.08 ± 0.60) ‰ (2σ, n = 4) and (0.038 ± 0.73) ‰ (2σ, n = 10), respectively. The results are in good agreement with those of previous studies. The results of the analysis of the same kind of rock mineral samples by the isotope laboratory of Maryland University and the author laboratory are compared and have good consistency within the error range. In addition, the quasi-standard NKT-1 nepheline rock (relative to IRMM-016) provided by the US Geological Survey is given a set of values, with a δ7Li value of (8.71 ± 0.46) ‰ (2σ, n = 4). Therefore, the present method can be used to determine the Li isotope composition of natural samples.