标准加入法在激光剥蚀电感耦合等离子体质谱测定粉末样品中的应用

Application of standard addition method in the determination of powder samples by LA-ICP-MS

采用固体混合制样方法研究了标准加入法在激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)测定粉末样品中的应用。以汽车尾气催化剂中贵金属元素为研究对象,选择具有2,4-二巯基-1,3,5-三嗪官能团的硅胶(DMT)定量吸附不同含量的贵金属元素,与汽车尾气催化剂混合均匀后,制备成薄片,使用LAICP-M S方法测定各元素强度,以强度为纵坐标,硅胶中待测元素为横坐标绘制工作曲线,通过标准加入法计算汽车尾气催化剂中贵金属元素含量。讨论了不同官能团硅胶的选择,pH对贵金属吸附的影响,制样方式对均匀性的影响。结果表明,使用DMT硅胶在pH 3.85时吸附贵金属,将硅胶与样品研磨均匀后制备的样品均匀性与重复性较好。将该方法用于汽车尾气催化剂分析用标准样品的测试,3种贵金属元素测定结果与标准样品认定值一致。

The application of standard addition method in the determination of powder samples by laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS)was studied by the solid-solid mixing sample preparation method.Taking precious metals in automobile exhaust catalyst as the target,silica gel(DMT)with 2,4-dimercapto 1,3,5-triazine functional group was selected to adsorb different contents of precious metals,and then mixed with automobile exhaust catalyst to press the mixed powder into disc.Intensity of each element was measured by LA-ICP-MS,and the content of precious metal in the automobile exhaust catalyst was calculated by standard addition method.The selection of silica gel with different functional groups,the influence of pH value on the adsorption of precious metals,and the influence of sample preparation methods on the uniformity of the sample were discussed.Results showed that the optimal pH value for adsorption of precious metals was 3.85,and the uniformity and repeatability of grinding samples were better.This method was used in the determination of certified reference materials for the analysis of automobile exhaust catalysts,and the results are consistent with the certified values.