碱熔共沉淀-电感耦合等离子体质谱法测定橄榄岩中的稀土元素  

Determination of Rare Earth Elements in Peridotite by Inductively Coupled Plasma-Mass Spectrometry after Alkali Fusion and Mg(OH)_2 and Fe(OH)_3 Coprecipitation

作　　者：黎卫亮[1] 程秀花[1] 李忠煜[1] 王鹏 

机构地区：[1]中国地质调查局西安地质调查中心,陕西西安710054 [2]中国地质大学(武汉)材料与化学学院,湖北武汉430074

出　　处：《岩矿测试》2017年第5期468-473,共6页Rock and Mineral Analysis

摘　　要：橄榄岩的稀土元素特征对研究岩石成因、岩浆作用过程具有重要的意义。橄榄岩中的稀土元素含量低(∑REEs=0.1~1μg/g),且存在镁、铁等基体元素的干扰,难以准确测定。前人通常利用高压密闭酸溶-离子交换法处理样品,将稀土元素与镁、铁等基体元素分离,达到了预富集的效果,但耗时长(消解时间接近7天)、操作步骤繁多,不利于大批量样品的分析。本文建立了过氧化钠碱熔、Fe(OH)_3和Mg(OH)_2共沉淀的样品前处理方法,通过离心使溶液与沉淀分离,从而实现了稀土元素与镁、铁等基体元素的快速分离,再采用电感耦合等离子体质谱法测定稀土元素含量。方法检出限为0.17~2.18 ng/g,加标回收率为95%~101%,国家标准物质(GBW07101和GBW07102)的测定值与标准值的相对误差小于20%,相对标准偏差(RSD,n=11)小于10%。该方法既减少了分步沉淀过程中带来的损失,也缩短了分析周期(消解时间仅需一天),操作简便,分析效率高。Characteristics of REEs in peridotite is significant for studying petrogenesis and magmatic processes.Due to the serious interference of matrix elements such as Mg and Fe,it is difficult to determine the low contents of REEs in peridotite (∑REEs = 0.1-1 μg/g) accurately.The previous method was sealed acid digestion at high pressure combined with ion-exchange which was used to separate REEs and matrix elements of Mg and Fe and preconcentrate REEs.However,due to the long digesting time (almost 7 days) and various operating steps,it is not conducive to the analysis of lots of samples.In this study,the sample was decomposed by Na_2O_2 alkali fusion,and coprecipitated with Mg(OH)_2 and Fe(OH)_3.Then,the solution was separated from precipitation by centrifuging for a rapid separation of REEs from matrix elements of Mg and Fe.Contents of REEs are determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS).For this method,the detection limits of REEs range from 0.17 to 2.18 ng/g,and the recoveries are 95%-101%.This method was used to analyze the national standard reference materials GBW07101 and GBW07102.The relative error between analytical results and recommended values is less than 20%,and the relative standard deviation (RSD,n = 11) is less than 10%.The method not only reduces the losses caused by stepped precipitation,but also shortens the analysis period (only one day for sample-digestion).It is simple to operate,and efficient in analysis.

关 键 词：橄榄岩 稀土元素 碱熔 共沉淀 电感耦合等离子体质谱法 

分 类 号：O614.33[理学—无机化学] O657.63[理学—化学]