电感耦合等离子体质谱法测定硒时多元素干扰的碰撞/反应研究及其在地质样品中的应用

Study on collision/reaction for multielement interference in determination of selenium by inductively coupled plasma mass spectrometry and its application to geological sample

采用电感耦合等离子体质谱仪(ICP-MS)在常规模式下测定硒时,由等离子体中大量氩原子所形成的多原子离子干扰不容忽视,使得硒的准确测定成为难题。控制碰撞气流量为4.5mL/min,载气流量为0.85L/min,ICP功率为1 300 W,采用碰撞/反应模式,以氢氦(体积比为7∶93)混合气为碰撞气体,80Se为测定同位素,降低了多原子离子的干扰,建立了一种电感耦合等离子体质谱法测定地质样品中硒的分析方法。在优化的实验条件下,方法检出限为0.08μg/g。采用实验方法对地质样品标准物质GBW07106、GBW07401、GBW07404及实际样品中的硒进行测定,结果与认定值或标准方法 NY/T1104—2006测定值基本一致,相对标准偏差(RSD,n=5)不大于6.0%。

The interference of polyatomic ions generated from a lot of argon in plasma could not be neglected during the determination of selenium by inductively coupled plasma mass spectrometry（ICP-MS）under normal mode.As a result,the accurate determination of selenium became a difficult problem.The collision gas flow rate was controlled at 4.5mL/min,the carrier gas flow rate was controlled at 0.85mL/min,and the ICP power was 1 300 W.The collision/reaction mode was adopted,and the interference of polyatomic ions was reduced with hydrogen-helium mixture（volume ratio of 7∶93）as collision gas and 80 Se as determination isotope.Consequently,a method was established for determination of selenium in geological samples by ICP-MS.The detection limit of method was 0.08μg/g under optimal experimental conditions.The content of selenium in geological certified reference materials（including GBW07106,GBW07401 and GBW07404）and actual samples was determined according to the experimental method.The results were basically consistent with the certified values or those obtained by standard method NY/T1104-2006.The relative standard deviations（RSD,n=5）were less than 6.0%.