混合酸敞开或高压密闭溶样-ICPMS测定地质样品中稀土元素

测定地质样品中的稀土元素时，用碱熔法处理样品过程繁琐，混合酸敞开酸溶法的酸种类多，用量较大，而微波消解法批次处理样品少，效率不高。本文比较了7种混合酸敞开酸溶体系、硝酸-氢氟酸高压密闭体系对样品溶样的效果，采用电感耦合等离子体质谱测定15个稀土元素的含量，建立了一套样品前处理体系简单、酸用量少、相对快捷的测定地质样品中稀土元素的方法。通过对59件国家标准物质的测试分析，结果表明硫酸-氢氟酸敞开酸溶和硝酸-氢氟酸高压密闭溶样两套体系的方法检出限、精密度、准确度均能达到地质行业相关标准测试要求。硫酸-氢氟酸敞开酸溶体系对于样品中钡含量较高，或样品量较少时适用；硝酸-氢氟酸高压密闭溶样体系的检出限更低，适用于大批量样品的分析测试。两套体系均不需要进行数学干扰校正，且酸用量少（最多6 mL），分析效率高（平均每日分析测试300件），有较大的推广应用价值。

Quick Determination of Rare Earth Elements in Geological Samples with Open Acid Digestion or High-pressure Closed Digestion by Inductively Coupled Plasma-Mass Spectrometry

Common pretreatment such as alkali fusion, open acid digestion and microwave digestion are unsuitable for the determination of rare earth elements (REEs) in geological samples. The process of the alkali fusion method is complicated. The open acid digestion system often contains 3, or even 5 kinds of acid, and the reagent consumption is large. The microwave digestion pretreatment only treats 8 to 9 samples per batch. A method with the advantages of simple pretreatment, small acid consumption and rapid determination for digestion of geological samples and determination of 15 Rare Earth Elements by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) is proposed here. Seven different acid digestion methods and the pressurized acid digestion method were studied by using 59 national standard reference materials. The analysis results show that the mixed acids of H₂SO₄ and HF under open system and the pressurized acid digestion with HNO₃ and HF method dissolved the samples effectively. The accuracy and precision of the proposed method match well with the geological standard. This method also demonstrates that the results are satisfied without mathematical calibration. The H₂SO₄-HF open acid digestion is suitable for less sample weight or high Ba content samples. The pressurized acid digestion of HNO₃ and HF method with lower detection limit is good for large quantities of samples. Both methods are reliable for REEs determination without mathematical interference correction. The acid consumption is less than 6 mL and up to 300 samples per day can be analyzed.