富铀矿岩石样品中痕量镉的精确测量方法

Accurate determination of trace cadmium in uranium-rich rocks samples

由于富铀矿岩石中伴生有大量的钼矿,而电感耦合等离子体质谱法测定痕量镉含量时,钼的氧化物会直接叠加到镉的质谱峰,造成质谱干扰,影响测量镉的正确度及精密度。研究了三种模式电感耦合等离子体质谱(ICP-MS)法测定富铀矿岩石中痕量镉Cd分析方法:膜去溶等离子体质谱(MCN-ICP-MS)法测定富铀矿岩石中痕量镉Cd含量的方法,能够高效降低钼的氧化物产率避免质谱干扰,将镉的灵敏度提高一个数量级,该方法的检出限为0.003μg·g^-1,精密度小于5.52%,正确度为2.31%;以He气为碰撞气的碰撞池等离子体质谱法(KED-ICP-MS)测定富铀矿岩石中痕量镉Cd含量的方法,能够有效减少钼的氧化物干扰,同时也降低了镉的灵敏度,该方法的检出限为0.011μg·g^-1,精密度小于8.63%,正确度为9.71%;氢化物发生等离子体质谱法(HG-ICP-MS)测定富铀矿岩石中痕量镉Cd含量的方法,该方法的检出限为0.003μg·g^-1,精密度小于7.33%,正确度为3.68%。

Because there are a large number of molybdenum ores associated with uranium-rich rocks,the spectral of molybdenum oxides will directly superimpose on the mass spectrum peaks of cadmium which will cause mass spectrum interference and affect the accuracy and precision of cadmium measurement in the content determination of trace cadmium by Inductively Coupled Plasma Mass Spectrometry(ICP-MS). In this paper, three modes of Inductively Coupled Plasma Mass Spectrometry(ICP-MS)were developed for the determination of trace Cadmium in uranium-rich rocks. The first modes is the membrane dissolution plasma mass spectrometry(MCN-ICP-MS). The mode can effectively reduce the yield of molybdenum oxides and avoid the interference of mass spectrometry,and increase the sensitivity of cadmium by one order of magnitude. The detection limit of this method is0.003 μg·g-1, the precision is less than 5.52 %, and the accuracy is 2.31 %. The second mode is the collision pool plasma mass spectrometry( KED-ICP-MS) with He as collision gas, the mode can effectively reduce the interference of molybdenum oxides and reduce the sensitivity of cadmium. The detection limit of this method is 0.011 μg·g-1, the precision is less than 8.63 %, and the accuracy is9.71 %. The third mode is the Hydride Generation Plasma Mass Spectrometry(HG-ICP-MS). The detection limit of this mode is 0.003 μg·g-1, the precision is less than 7.33 % and the accuracy is3.68 %.