封闭压力酸溶-盐酸提取-电感耦合等离子体质谱法测定地质样品中的多元素

Quantification of Multi Elements in Geological Samples by Inductively Coupled Plasma-Mass Spectrometry with Pressurized Decomposition-Hydrochloric Acid Extraction

高温、高压封闭压力酸溶可有效分解岩石、土壤、沉积物等地质样品,采用电感耦合等离子体质谱法(ICP-MS)进行测定,大部分元素可得到满意的回收率;但Zr、Hf、REEs、Rb、Th、U等元素用硝酸复溶困难,测定结果不准确。本文对传统的封闭压力酸溶方法进行改进,用盐酸复溶提取代替硝酸复溶提取,ICP-MS法测定岩石、土壤、沉积物等国家一级标准物质中Li、Be、Cr、Mn、Co、Ni、Cu、Zn、Ga、Rb、Sr、Mo、Cd、In、Cs、Ba、Ti、Zr、Nb、Sn、Sb、W、Hf、Ta、Tl、Pb、Bi、Th、U以及稀土元素(REEs)等46个元素。将原方法中的称样量25 mg加大至100 mg,溶样时间由12 h延长至48 h,有效地解决了取样代表性及HNO3复溶提取时Rb、Sr、REEs等元素测定结果偏低的问题。分析结果表明,除元素As和V在电感耦合等离子体质谱测定中存在Cl的干扰不能准确测定之外,其他44个元素的测定值与标准值基本一致。改进后的方法测定下限为0.01～0.85μg/g,精密度(RSD,n=10)为0.73%～13.1%,准确度小于<10%。方法准确、可靠,适用于各种不同种类地质样品的分析。

Rock,soil,sediments and other geological samples can be effectively decomposed by acid under high temperature and pressure,and be measured by Inductively Coupled Plasma-Mass Spectrometry（ICP-MS）.The recoveries of most elements were satisfactory,except for the results of Zr,Hf,REEs,Rb,Th,and U.In this paper,the traditional pressurized acid digestion method has been improved as the sample was extracted by hydrochloric acid instead of nitric acid.46 elements in the National Standard Materials of rock,soil and sediments can be accurately determined by this improved method.Sample weight was increased from 25 mg to 100m and digestion time was extended from 12 h to 48 h,which effectively resolved the problems including the representation of the samples and inadequate results for Rb,Sr,REEs and other elements dissolved by HNO3.The results of many experiments showed that the 44 elements measured were consistent with standard values except for As and V elements,according to Cl interference in ICP-MS.Detection limits of the improved method were 0.01-0.85 μg/g,with a precision RSD（n=10） of 0.73%-13.1% and an accuracy RE（n=10）of less than 10%.The improved method is accurate,reliable and suitable for a variety of different types of geological samples.