全自动石墨消解-电感耦合等离子体质谱法测定土壤和水系沉积物中稀土元素

稀土元素由于化学性质稳定，均一化程度高，常作为地球化学示踪剂，为揭示岩石、矿物成因、成岩成矿的地球化学条件以及物质来源和岩浆分异演化等提供重要信息，因此，建立快速、准确地测定地质样品中稀土元素含量的方法非常重要。地质样品因基体复杂，大部分的样品前处理需要酸溶，酸溶试剂用量大，溶样过程中产生的酸雾易对实验人员造成伤害，且批量样品前处理劳动强度大。基于此，本文建立了以全自动石墨消解仪消解样品，“加酸—消解—赶酸—定容—摇匀”全程用软件控制，以Rh和Re为内标，电感耦合等离子体质谱法（ICP-MS）测定土壤和水系沉积物中La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、Y等15个稀土元素的方法。通过12个土壤和水系沉积物国家一级标准物质对消解程序、消解混合酸及方法精密度、准确度和检出限进行研究。结果表明：按照优化后的消解程序消解土壤和水系沉积物，混合酸用量为4mL，稀土各元素测定值与标准值一致，相对误差（RE）绝对值在0～6.67%之间，ΔlgC绝对值在0～0.028之间，相对标准偏差（RSD）在0.97%～4.62%之间。全自动石墨消解因自动化操作，操作条件一致，温度均匀，精度更高，各元素的RSD值均小于电热板消解的元素RSD值。本方法精密度、准确度和检出限满足《地质矿产实验室测试质量管理规范》的要求，混合酸用量远低于常用的电热板消解法，相应的环境污染也减少；方法精密度优于常用的电热板消解法。前处理时只需要称样后将消解管置于石墨消解仪中，溶样全过程自动完成，自动化程度高，适用于批量样品的测试。

Determination of Rare Earth Elements in Soil and Stream Sediment by Inductively Coupled Plasma-Mass Spectrometry with Automatic Graphite Digestion

BACKGROUNDRare earth elements were used as geochemical tracers usually to provide important information for revealing the genesis of rocks and minerals, geochemical conditions of diagenesis and mineralization, material sources and magmatic differentiation and evolution, due to their stable chemical properties and high degree of uniformity. Therefore, it was very important to develop a method for rapidly and accurately determining the contents of rare earth elements in geological samples. In addition, due to the complex matrix of geological samples, most samples needed to be acid-dissolved in pre-treatment, and the amount of acid-dissolved reagents was large. The acid mist generated in the process of sample dissolution was harmful to the experimental personnel and the labor intensity of batch sample pretreatment was high.