阳离子树脂交换分离-电感耦合等离子体质谱法测定地球化学样品中硼砷溴钨

在多目标地球化学调查测试的方法中,硼、砷、溴、钨4个元素涉及多种测试方法,分析成本高,且检测效率低。采用氢氧化钠和过氧化钠碱熔法处理样品,用乙醇、沸水提取后,采用732型阳离子树脂进行交换分离以实现Na⁺与目标元素的分离,建立了电感耦合等离子体质谱法(ICP-AES)测定地球化学样品中硼、砷、溴、钨的方法。考察了732型阳离子交换树脂用量、吸附时间对测定的影响,结果表明,选择树脂用量为5 g,吸附时间为1 h时,溶液中Na⁺可控制在0.05 g/L及以下;考察了清洗方法对记忆效应的影响,结果表明,测定完成后用2%氨水清洗2 min可消除记忆效应,对于个别高含量样品,可以适当增加清洗时间至3 min。在优化的实验条件下,硼、砷、溴、钨4种元素校准曲线的线性相关系数均大于0.999,方法检出限为0.12～0.60 μg/g,定量限为0.41～1.99 μg/g。按照实验方法分析了6个水系沉积物和土壤标准物质中的硼、砷、溴、钨,测定值与认定值的对数差(ΔlgC)为-0.043%~0.048%,满足DZ/T 0130—2006《地质矿产实验室测试质量规范》的要求。采用实验方法对地球化学样品中的硼、砷、溴、钨进行测定,与多目标地球化学调查测试方法进行方法比对,结果并无显著性差异,实验方法测定结果的相对标准偏差(RSD,n=12)为2.0%~4.7%。

Determination of boron,arsenic,bromine and tungsten in geochemical samples by cation resin exchange separation-inductively coupled plasma mass spectrometry

In the multi-objective geochemical investigation, several testing methods are involved for the determination of four elements including boron, arsenic, bromine and tungsten. The analysis cost is high, and the detection efficiency is low. The sample was treated by alkali fusion with sodium hydroxide and sodium peroxide in experiments. After extraction with ethanol and boiling water, the 732-cation resin was adopted for exchange separation, realizing the separation of sodium ions from the target elements. A method for the determination of boron, arsenic, bromine and tungsten in geochemical samples by inductively coupled plasma mass spectrometry (ICP-AES) was established. The effect of 732-cation exchange resin dosage and the adsorption time on the determination was investigated. The results showed that Na⁺ in solution could be controlled below 0.05 g/L when the dosage of resin was 5 g and the adsorption time was 1 h. The influence of cleaning method on the memory effect was also studied. The results showed that the memory effect could be eliminated by cleaning with 2% ammonia water for 2 min after determination. For some samples with high contents, the cleaning time could be properly increased to 3 min. Under the optimized experimental conditions, the linear correlation coefficients of calibration curves for four elements were all greater than 0.999. The limits of detection were between 0.12 and 0.60 μg/g, and the limits of quantification were between 0.41 and 1.99 μg/g. The contents of boron, arsenic, bromine and tungsten in six certified reference materials of stream sediment and soil were analyzed according to the experimental method. The logarithmic differences (ΔlgC) between the determination results and certified values were between -0.043% and 0.048%, which could meet the requirements of DZ/T 0130-2006 The specification of testing quality management for geological laboratories. The contents of boron, arsenic, bromine and tungsten in geochemical samples were determined according to the experimental method and compared with the analysis method for multi-objective geochemical investigation. The results had no significant difference. The relative standard deviations (RSD, n=12) of determination results were between 2.0% and 4.7%.