电感耦合等离子体质谱法测定金属矿中稀土和稀散元素

金属矿中稀土和稀散元素的测定对其综合利用具有重要意义。难溶元素Nb、Ta、Zr、Hf采用酸溶法处理时较难溶解完全,Nb、Ta采用碱熔法处理后再用王水浸取存在不稳定的问题。实验采用偏硼酸锂熔融样品,酒石酸体系浸取,解决了上述Nb、Ta等元素测定中遇到的难题。通过选择待测同位素和干扰校正方法在线校正,以10 μg/L¹⁸⁵Re和10 μg/L¹⁰³Rh为混合内标,采用电感耦合等离子体质谱法(ICP-MS)对浸取液进行测定,实现了对金属矿中La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、Y共15种稀土元素,及Nb、Ta、Zr、Hf、Ga、Rb、Cd、Cs、In、Tl共10种稀散元素的测定。方法校准曲线的线性相关系数均大于0.999 7,方法检出限为0.03～0.85 μg/g,定量限为0.09～2.55 μg/g。将实验方法应用于铅矿石、钨矿石、钽矿石和锆矿石标准物质中稀土和稀散元素的测定,结果的相对误差(RE)为-5.33%～6.67%,相对标准偏差(RSD,n=12)不大于9.8%。采用实验方法对洛宁铅锌多金属矿区的样品进行测定,结果的相对标准偏差(n=5)不大于9.3%。

Determination of rare earth and scattered elements in metallic ores by inductively coupled plasma mass spectrometry

The determination of rare earths and scattered elements in metallic ores is of great significance for the comprehensive utilization of metallic ores. It is difficult to completely decompose the insoluble elements including Nb, Ta, Zr and Hf in acid dissolution treatment. If Nb and Ta are treated by alkali fusion followed by leaching with aqua regia, there is the problem of instability. The sample was fused with lithium metaborate followed by leaching with tartaric acid system in experiments, solving the problems in determination of Nb and Ta mentioned above. The testing isotopes and interference correction methods were selected for online correction. 10 μg/L ¹⁸⁵Re and 10 μg/L ¹⁰³Rh were used as mixed internal standards. The leaching solution was determined by inductively coupled plasma mass spectrometry (ICP-MS), realizing the determination of 15 rare earths (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y) and 10 scattered elements (Nb, Ta, Zr, Hf, Ga, Rb, Cd, Cs, In and Tl) in metallic ores. The correlation coefficients of calibration curves in proposed method were all higher than 0.999 7. The limits of detection were between 0.03 μg/g and 0.85 μg/g, and the limits of quantification were between 0.09 μg/g and 2.55 μg/g. The proposed method was applied for the determination of rare earths and scattered elements in certified reference materials of lead ore, tungsten ore, tantalum ore and zirconium. The relative errors (RE) of results were between -5.33% and 6.67%. The relative standard deviations (RSD, n=12) were not more than 9.8%. The lead-zinc metallic ore samples from Luoning were determined according to the experimental method, and the RSDs of results were not more than 9.3%.