高分辨电感耦合等离子体质谱法测定地质样品中稀土元素的氧化物干扰研究  

Characterization of Oxide Interference for the Determination of Rare Earth Elements in Geological Samples by High Resolution ICP-MS

作　　者：王冠[1] 李华玲[2] 任静[1] 杨波[1] 胡志中[1] 

机构地区：[1]成都地质矿产研究所,四川成都610082 [2]南京地质矿产研究所,江苏南京210005

出　　处：《岩矿测试》2013年第4期561-567,共7页Rock and Mineral Analysis

基　　金：成都地质调查中心青年基金资助项目;中国地质大调查项目"云南麻栗坡地区矿产远景调查"(1212010880402)

摘　　要：电感耦合等离子体质谱(ICP-MS)用于测定稀土元素经常会引起M+、MO+、MOH+离子的质谱重叠干扰,其中制约分析准确度和精密度的主要因素是多原子离子干扰,尤其是轻稀土元素的氧化物和氢氧化物对重稀土元素的干扰,以及钡的7个天然同位素形成的氧化物和氢氧化物对轻稀土元素的干扰。本文采用高温高压密闭消解地质样品,高分辨电感耦合等离子体质谱法(ICP-MS)测定其中的痕量稀土元素,研究了低、中、高三种分辨率模式下氧化物的干扰情况,确定了最佳的测定同位素和合适的分辨率。分析结果表明,在低、中分辨率模式下,轻稀土元素Ce、Pr、Nd、Sm的氧化物和Ba的氧化物干扰明显,Gd元素的测定值严重偏离;在高分辨模式下,Ba氧化物对Eu的干扰以及大部分轻稀土元素氧化物对重稀土元素的干扰基本可以消除,无需进行校正,而只有157Gd受到141Pr16O的干扰突出,当样品中Pr/Gd的浓度比值大于100时,Gd的测量值必须进行数学校正。The main factor which limits the analysis accuracy and precision in the determination of rare earth elements （REEs） in geological samples is the interference of polyatomic ions, especially the interferences from oxide and hydroxide of light rare earth elements and natural Ba isotopes. A method for the determination of REEs in geological samples has been developed by using high temperature and pressure digestion and performing measurements using High Resolution Inductively Coupled Plasma-Mass Spectrometry （HR-ICP-MS）. The oxide interferences were studied under low, moderate and high resolution modes, in order to select the best measured isotopes and appropriate resolution. The results show that oxides of light rare earth elements Ce, Pr, Nd, Sm and Ba oxide will produce interferences under low or middle resolution modes, and the value of Gd is seriously deviated. Under high resolution mode, the interference from 157Gd cannot be eliminated completely. When the Pr/Gd ratio is greater than 100, the value of Gd must be mathematically corrected. Meanwhile, interference corrections are unnecessary for light REEs oxide and hydroxide on heavy REEs and Ba on Eu.

关 键 词：地质样品 稀土元素 高分辨电感耦合等离子体质谱法 氧化物干扰 

分 类 号：O614.33[理学—无机化学] O657.63[理学—化学]