电感耦合等离子体质谱法测定白云鄂博矿石中15种稀土元素总量及其分量

白云鄂博矿物为典型的晶格型矿物,含有铌、锆、钛等难溶金属的矿物,常规酸溶法处理难以将其溶解完全。采用氢氧化钠和过氧化钠碱熔融分解白云鄂博矿石样品,热水浸取,碱分离后,用盐酸和过氧化氢破坏滤纸和溶解沉淀,以1%盐酸为测定介质,通过控制基体质量浓度不大于0.5 g/L和采用Cs内标进行校正以消除基体效应,建立了电感耦合等离子体质谱法(ICP-MS)测定白云鄂博矿石中包括镧、铈、镨、钕、钐、铕、钆、铽、镝、钬、铒、铥、镱、镥、钇在内的15种稀土元素含量及其总量的方法。实验表明,各稀土元素在质量浓度为5.00~100.0 ng/mL(以氧化物计,下同)范围内和稀土元素与内标元素的强度比呈良好的线性关系,相关系数均不小于0.999 6。方法检出限为0.010~0.034 ng/mL,定量限为0.030~0.10 ng/mL。按照实验方法对白云鄂博矿石样品中稀土元素总量及其分量进行测定,测定结果与电感耦合等离子体原子发射光谱法或X射线荧光光谱法基本一致;相对标准偏差(RSD,n=6)在1.0%~4.9%之间,加标回收率在95%~105%之间。将实验方法应用于稀土矿石成分分析标准物质中稀土元素总量及其分量的测定,结果与认定值基本一致。

Determination of total amount of fifteen rare earth elements and its component in Bayan Obo ore by inductively coupled plasma mass spectrometry

Bayan Obo ores are typical lattice minerals, containing insoluble minerals such as niobium, zirconium, and titanium, which are difficult to be completely dissolved by conventional acid solution treatment. In experiments, Bayan Obo ore sample was melted and decomposed by sodium hydroxide and sodium peroxide. After leaching with hot water and alkali separation, the filter paper and the precipitate were destroyed and dissolved with hydrochloric acid and hydrogen peroxide. 1% hydrochloric acid was used as the measurement medium. The mass concentration of the matrix was controlled below 0.5 g/L. Cs was selected as internal standard to eliminate the matrix effect. Accordingly, the determination of total amount of fifteen rare earth elements (including lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and yttrium) and its component in Bayan Obo ore by inductively coupled plasma mass spectrometry (ICP-MS) was established. The experiments showed that the mass concentration of each rare earth element in range of 5.00-100.0 ng/mL (in oxide, similarly hereinafter) had a good linear relationship with the intensity ratio between rare earth element and internal standard. The correlation coefficients were not less than 0.999 6. The limits of detection were in range of 0.010-0.034 ng/mL, and the limits of quantification were in range of 0.030-0.10 ng/mL. The total amount of fifteen rare earth elements and its component in Bayan Obo ore were determined according to the experimental method. The found results were basically consistent with those obtained by inductively coupled plasma atomic emission spectrometry or X-ray fluorescence spectrometry. The relative standard deviations (RSD, n=6) were between 1.0% and 4.9%. The spiked recoveries ranged from 95% to 105%. The proposed method was applied for the determination of total amount and its component of rare earth elements in certified reference materials. The measured results were basically consistent with the certified values.