A method to determine concentrations of 15 rare earth elements in soil and sediments by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) with microwave digestion is reported in this paper. Experimental conditions such as sample dissolution reagents, microwave digestion procedure, standard solution preparation, mass spectrum interferences and internal standards were studied. The samples were dissolved completely by the addition of HF acid. The dissolving rate of rare earth elements (REEs) was improved by using mix HNO3-HF-H2O2 reagent. The interference effects among REEs can be minimized by using matched calibration solutions with a similar composition to soil and sediments. Polyatomic ions inferences were calibrated by equivalent concentrations, calculated by the measured ratios of MO+/M+ and MOH+/M+ of individual La, Ce, Pr, Nd and Ba solution. 103Rh was selected as an internal standard to calibrate the analytical signal drift. The detection limits for the method were 1.2 -7. 1 ng/g, the relative standard deviation (RSD, n=6) was less than 5. 3% and recoveries were 86. 1% - 110. 1%. The accuracy and precision of the method were validated by reference materials and the results were consistent with the certified values. This method is simple, rapid, has good reproducibility and wide linearity, all of which meets the requirements for the analysis of large batches.%建立了微波消解-电感耦合等离子体质谱法测定土壤和沉积物中15种痕量稀土元素的分析方法.研究了溶样试剂、微波消解程序、标准溶液配制、质谱干扰与内标元素对稀土元素测定的影响.加入氢氟酸能有效打开样品,以HNO3 -HF- H2O2混合酸溶解样品,稀土元素的溶出率较高.采用模拟土壤、沉积物中稀土元素天然组成比值的校正溶液,对稀土元素间的干扰具有明显的抑制作用.通过测定单个La、Ce、Pr、Nd和Ba的氧化物及氢氧化物产率,计算出等效干扰浓度,进而校正多原子离子干扰.利用103Rh内标校正系统,有效地抑制了分析信号的动态漂移.方法检出限为1.2 ～7.1 ng/g,精密度(RSD)≤5.3％(n=6),加标回收率为86.1％～110.1％.使用土壤、沉积物标准物质进行验证,测定结果与标准值相符.建立的方法样品处理程序简单快速、线性范围宽、分析重现性好、结果准确,适用于大批量地质样品的分析.
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