激光剥蚀-电感耦合等离子体质谱:双外标结合基体归一定量校准策略

Laser Ablation-Inductively Coupled Plasma-Mass Spectrometer:A Quantification Strategy Based on Two Reference Materials and Bulk Normalization as 100%(wt)

定量校准策略是激光剥蚀电感耦合等离子体质谱(AICP-MS)分析技术的重要组成部分,直接影响分析数据的质量。本研究评估了现有玻璃标准物质定值不确定度的相对大小,并探究了NIST、MPI-DING和USGS系列玻璃标准物质之间的基体效应。结果表明,NIST610的定值不确定度优于其它玻璃标准物质,在本实验条件下,NIST、MPI-DING和USGS系列玻璃标准物质之间的基体效应可忽略不计。在此基础上提出了双外标结合基体归一定量校准策略,外标分别为NIST610和St Hs6/80-G。此策略克服了由于NIST610主量成分与地质样品差别大而造成的主量元素准确度差以及St Hs6/80-G中某些微量元素含量低、定值不确定度较大等缺点。对比采用3种定量校准策略(单外标NSIT610基体归一法、单外标St Hs6/80G基体归一法和双外标基体归一法)校准的ML3B-G数据可知,双外标基体归一法有效避免了单外标基体归一法的不足,并提高了分析数据的准确度。采用双外标结合基体归一定量校准策略校准了BCR-2G、CGSG-2和KL-2G中的主量元素和微量元素。结果表明,绝大多数分析数据在定值不确定度范围内,验证了此校准策略的实用性。同时,本研究得到的主量微量元素数据进一步补充了BCR-2G、CGSG-2和KL-2G的定值数据库。

Quantitative calibration strategy as an essential issue in laser ablation ICP-MS plays an important role for the guarantee of analytical accuracy. In this study,uncertainties of reference values in current available glass certified reference materials( NIST,MPI-DING and USGS) as well as the matrix effect among them were systematically evaluated. The results illustrated that NIST610 was better than other reference materials from aspect of reference value uncertainty. The matrix effect among NIST,MPI-DING and USGS reference materials was insignificant under our experimental conditions. A quantification strategy based on two reference materials( NIST610 and St Hs6/80-G) and normalization to 100%( w/w) was proposed to avoid the insufficiency of single reference material strategy,which suffered the very low content and large uncertainty for some elements.The comparision of ML3B-G results obtained from three quantification strategies( single reference material NIST610,single reference material St Hs6/80-G and two refterence materials) illustrated that the proposed strategy improved the analytical accuracy. Three reference materials( BCR-2G,CGSG-2 and KL-2G) were quantified with the proposed strategy,and almost all data matched well with reference value,meanwhile the data reported here could supplement the reference value database.