Exposure, Epidemiology, and Risk Program, Department of Environmental Health, Harvard School of Public Health , Boston, Massachusetts 02215, United States.
Environ Sci Technol. 2014 Oct 21;48(20):12150-6. doi: 10.1021/es502989j. Epub 2014 Oct 2.
There is growing concern about the accuracy of trace elemental analysis of ambient particulate matter (PM) samples. This has become important because ambient PM concentrations have decreased over the years, and the lower filter loadings result in difficulties in accurate analysis. The performance of energy-dispersive X-ray reflectance spectrometry was evaluated at Harvard School of Public Health using several methodologies, including intercomparison between two other laboratories. In reanalysis of standard films as unknown samples following calibration, the HSPH ED XRF measurements represented good performance: 2% errors in precision and 4% errors in accuracy. Replicate analysis of ambient air filters with low PM2.5 levels indicated that S, K, Fe, and Ca showed excellent reproducibility, most other quantifiable elements were below 15% error, and the elements with larger percent of flagged measurements had less in precision. Results from the interlaboratory comparison demonstrated that most quantifiable elements, except Na and Al, were quite comparable for the three laboratories. Na performance could be validated from the stoichiometry of Na to Cl of indoor PM2.5 filter samples.
人们越来越关注环境颗粒物 (PM) 样品中微量元素分析的准确性。这一点变得很重要，因为近年来环境 PM 浓度有所下降，而较低的滤膜负荷导致分析的准确性出现困难。哈佛公共卫生学院采用了多种方法对能量色散 X 射线反射光谱法的性能进行了评估，包括与另外两个实验室之间的相互比较。在对标准滤膜进行重新分析作为校准后的未知样品时，HSPH ED XRF 测量结果表现出良好的性能：精密度误差为 2%，准确度误差为 4%。对 PM2.5 水平较低的环境空气滤膜进行重复分析表明，S、K、Fe 和 Ca 表现出极好的重现性，大多数其他可量化元素的误差在 15%以下，而标记测量元素的百分比较大的元素的精密度较低。来自实验室间比较的结果表明，除了 Na 和 Al 之外，三个实验室的大多数可量化元素都非常相似。Na 的性能可以通过室内 PM2.5 滤膜样品中 Na 与 Cl 的化学计量关系来验证。
