电感耦合等离子体串联质谱法测定 高纯氧化镁粉中金属杂质元素

基于电感耦合等离子体串联质谱(ICP-MS/MS)法建立了准确可靠分析高纯氧化镁粉中金属杂质元素的新方法。ICP-MS/MS通过启用新的质量过滤装置,在氧化镁基质的金属杂质元素测定过程中,能有效减少多原子干扰。采用He为碰撞气,O₂以及NH₃/He混合气为反应气,对比了在单四极杆(SQ)模式和串联四极杆(MS/MS)模式下消除干扰的效果。采用He碰撞模式无法消除一些特殊的质谱干扰,特别是双电荷离子干扰;然而,将分析物转移为氧化物离子或团簇离子,能实现待测元素的无干扰分析,并能获得极低的检出限,通过加标回收实验评估了方法的准确性。结果显示,方法的检出限为0.46~65.9ng/L。各元素的线性相关系数(R²)均不小于0.9998,真实样品的加标回收率为93%~108%,相对标准偏差为1.6%~4.4%。方法完全能用于高纯氧化镁粉中金属杂质元素的实时监控。

Determination of metal impurity elements in high purity magnesium oxide powder by inductively coupled plasma tandem mass spectrometry

The new analysis method of metal impurity elements in high purity magnesium oxide powder with good accuracy and reliability was established based on inductively coupled plasma tandem mass spectrometry (ICP-MS/MS). New mass filtering device was adopted in ICP-MS/MS to effectively reduce the polyatomic interference during determination of metal impurity elements in magnesium oxide matrix. Helium was used as collision gas, while O₂ and NH₃/He mixture was used as reaction gas. The elimination effect of interference was compared at single quadrupole (SQ) mode and tandem quadrupole (MS/MS) mode. It was found that some special MS interference could not be eliminated by helium collision mode, especially for the double charge ion interference. However, the conversion of analyte to oxide ion or cluster ion could realize the non-interference analysis of testing elements. Moreover, the detection limit was very low. The accuracy of method was evaluated by spiked recovery experiments. The results showed that the detection limit was 0.46-65.9ng/L. The linear correlation coefficients (R²) of elements were not less than 0.9998. The recoveries of actual samples were between 93% and 108%. The relative standard deviations (RSD) were between 1.6% and 4.4%. The proposed method could be applicable for the real-time monitoring of metal impurity elements in high purity magnesium oxide powder.