动态反应池-电感耦合等离子体质谱法精确测定配分差异显著的重稀土元素

Determination of heavy rare earth elements of special rare earth ores by inductively coupled plasma mass spectrometry with a dynamic reaction cell

采用微波辅助消解样品,以O_2为反应气,动态反应池-ICP-MS（ICP-DRC-MS）法测定样品中Gd、Tb、Dy、Ho、Er、Tm的含量,在选定的工作条件下,除Tm（81.09%）外,其他元素氧化物的产率均在99%以上,轻稀土元素二氧化物离子产率一般都低于0.3%。研究认为,轻稀土元素（Ce、Pr、Nd）二氧化物离子对重稀土（Gd、Tb、Dy、Ho、Er、Tm）氧化物离子的干扰可有效扣除;只有Gd O＋受到未反应的Yb＋的谱线重叠干扰比较严重。白云鄂博稀土矿石样品中Gd元素含量一般比Yb高几十倍,此干扰也可以利用干扰系数校正法扣除。轻、重稀土元素分离后ICP-MS法的测定结果进一步验证了方法的准确性。该法检出限范围为0.002~0.023μg/g,精密度在0.87%~2.18%,完全能够满足白云鄂博稀土矿石样品中重稀土元素的分析要求。

The rare earth elements（ REE） distribution pattern of Bayan Obo rare earth ores is different significantly,therefore the interference from oxide and hydroxide of light rare earth elements（ LREE） to heavy rare earth elements（ HREE） is serious. The content of HREE can not be determined accurately by Inductively Coupled Plasma Mass Spectrometry（ ICP-MS）. A method for the determination of Gd,Tb,Dy,Ho,Er,Tm is developed by microwave digestion and performing measurements by Inductively Coupled Plasma Mass Spectrometry in a Dynamic Reaction Cell（ ICP-DRC-MS）. Under the selected conditions,the conversion of REE to molecular monoxide ions was nearly quantitative（ 〉99%）,with the exception of Tm（ 81. 09%）. Moreover,the formation of dioxide ions was generally lower than 0. 3%. The result shows that the interferences due to dioxide and un-reacted ions can be deducted effectively,and the un-reacted ytterbium generated significant spectral interferences on Gd O due to the formation of ytterbium oxide is quite limited. Since the content of Gd is generally dozens times higher than Yb,the interference can also be deducted. The accurate determination of Gd,Tb,Dy,Ho,Er,Tm was achieved by ICP-MS for comparison after separation by Ln. Spec resin. The detection limit was 0. 002- 0. 023 μg / g,and the relative standard deviation（ RSD） for all components was between 0. 87%-2. 18%.