样品量的大小对铜锌同位素测定值的影响  

Effects of Sample Size on Cu and Zn Isotope Ratio Measurements

作　　者：闫斌[1,2] 朱祥坤[2] 陈岳龙[1] 

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]中国地质科学院地质研究所国土资源部同位素重点实验室,北京100037

出　　处：《岩矿测试》2011年第4期400-405,共6页Rock and Mineral Analysis

基　　金：国家自然科学基金(40973037;40921001);中国地质调查局地质调查项目(1212010911046;1212010711815)

摘　　要：利用多接收电感耦合等离子体质谱法测定铜、锌同位素比值时,样品量的大小对其同位素测定值存在一定的影响。本研究中使用不同量的实验室标准溶液(CAGS-Cu、CAGS-Zn)过柱,并以该标准溶液为基准,采用标准-样品交叉法测定铜、锌同位素比值。结果表明,当铜、锌的样品量小到一定程度时,其同位素测定值偏离真值;当铜、锌的样品量足够大时,其同位素测定值趋于真值。流程本底对同位素测定值的影响可忽略不计,同时也不存在同质异位素干扰,说明这一现象极可能来自所用试剂和离子交换树脂的杂质组分产生的基质效应。在本文报道的实验条件下,当铜的样品量≥4μg、锌的样品量≥1μg时才能够确保铜、锌同位素测定结果的准确性。这一现象是否在其他同位素体系的测试过程存在,是个值得注意的问题。Using multi-collector inductively coupled plasma mass spectrometry（MC-ICP-MS） to measure copper and zinc isotopes,the sample weighting can influence the measurements of copper and zinc isotopic ratios.Different amounts of copper and zinc laboratory reference solutions（CAGS-Cu,CAGS-Zn） were loaded and passed through a column of ion exchange resin.The sample-standard bracketing technique was applied for the measurements of Cu and Zn.The measured data were corrected using certified values of laboratory reference solutions.The results showed δ66Cu and δ66Zn deviate from true values for small sample weighting of copper and zinc;conversely,the isotopic value tends to the true values for large sample weighting.Procedure blank and isobaric interferences can be ignored for the isotopic values,which seems to indicate that the problem lies with the matrix effect from the Ion Exchange Resin and reagents.Therefore,using values for sample weighting of 4 μg for copper and 1 μg for zinc,accurate isotopic ratios can be guaranteed under these experimental conditions.

关 键 词：铜同位素 锌同位素 样品量 基质效应 多接收器等离子体质谱 

分 类 号：P575.9[天文地球—矿物学]