LA-ICP-MS微区原位准确分析含水硅酸盐矿物主量和微量元素

通过描述一种利用LA-ICP-MS准确测定含水硅酸盐矿物主量元素和微量元素含量的多外标、无内标分析方法.总结出该方法基于矿物化学计量式计算含水硅酸盐矿物中挥发分的相对含量，再将全部分析元素归一化到总金属氧化物含量(100%减含水量)的原理，利用多种天然成分的岩石标准玻璃(如MPI-DING玻璃和USGS玻璃)作为外标进行校正计算.利用该方法对角闪石、绿帘石、电气石和透闪石等含水硅酸盐矿物进行了分析，并与利用电子探针和微钻(直径300 μm)取样溶液-ICP-MS分析的结果进行了对比研究.研究结果表明:对于组成均一的主量元素的分析结果与电子探针分析数据一致，相对偏差集中在5%以内.除了那些分布异常不均一的元素(在300 μm尺度上)，对微量元素的分析结果与溶液-ICP-MS分析结果具有很好的一致性，二者之间的相对偏差大部分集中在10%以内.研究结论为采用归一化校正策略，选择MPI-DING和USGS玻璃作为外标，利用LA-ICP-MS微区分析方法可以准确测定含水硅酸盐矿物中的主、微量元素含量. 

In Situ Analysis of Major and Trace Element Compositions of Hydrous Silicate Minerals by LA-ICP-MS

This paper presents a calibration strategy for LA-ICP-MS accurate analysis of major and trace elements of hydrous silicate minerals, which is internal standard-independent and applies multiple reference materials for external calibration. The total content of the volatile components in the hydrous silicate minerals was firstly calculated based on the mineral constant stoichiometry. Then, major and trace elements were quantified by calibrating against multiple reference materials (e.g., MPI-DING and USGS glasses) combined with normalization of all metal oxides to the sum of 100% minus the total volatile components. Analyses of amphibole, tremolite, tourmaline as well as epidote by LA-ICP-MS using the calibration strategy match the results of electron microprobe analyses within 5% uncertainty for the major elements which are homogeneous in samples. The results are consistent with the analysis of solution-ICP-MS combined with microsampling (diameter=300 μm) within generally 10% uncertainty for trace elements, except for those elements distributed heterogeneously in the samples. The results show that major and trace elements of hydrous silicate minerals can be accurately analyzed by LA-ICP-MS without applying internal standardization when using MPI-DING and USGS reference glasses as multiple reference materials for calibration.