能量色散X射线荧光光谱法测定大气颗粒物中无机元素应用程序的建立、评估与维护

用能量色散X射线荧光光谱法(ED-XRF)测定大气颗粒物滤膜样品中Na、Mg、Al、Si、P、S、Cl、K、Ca、Ti、V、Cr、Mn、Fe、Co、Ni、Cu、Zn、As、Pb、Sr、Ba等无机元素,不需要样品前处理,分析方法具有快速、准确的特点,方法标准已颁布实施。基于多年的应用经验,总结出建立应用程序时的要点如下:存在干扰时,应采用全谱图拟合方式对重叠谱峰进行解析,可扣除或减小干扰峰的影响,得到目标元素特征谱峰强度;为保证Na-Kα、Mg-Kα、l-Kα、Si-Kα的谱线拟合,参与拟合的谱线中应去掉位于相同或相近位置上的Lα谱线;存在干扰或相互干扰的元素如As-Pb、Fe-Co、Ti-V-Ba、Fe-Mn、Mn-Cr等,必须在相同分组条件下同时测定;滤光片的合理使用有利于提高信噪比,降低背景值,特别是对于低含量元素,背景扣除是否准确对结果影响很大;校准曲线回归后参数截距设置为0,可有效避免薄膜标样支撑膜上杂质对后续样品检测结果影响;市场上缺乏颗粒物滤膜标样时,不同分析技术、不同仪器测试结果及多家实验室间对相同颗粒物样品测试结果比对,可有效发现应用程序存在的问题。多年应用经验表明,国产模拟颗粒物滤膜标准样品和轻元素X射线荧光强度再校准样品尽快进入市场,对于有效监控荧光强度波动性,保证样品测试结果的一致性和不同实验室间相同样品测试结果的可比性具有重要意义。

Determination of inorganic elements in atmospheric particles by energy dispersive X-ray fluorescence spectrometry: establishment,evaluation and maintenance of the application program

During the determination of inorganic elements (Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Pb, Sr and Ba) in filtration membrane of atmospheric particles by energy dispersive X-ray fluorescence spectrometry (ED-XRF), the pretreatment of sample is not required. The analysis method is rapid and accurate, and the standard method has been issued and implemented. Based on many years of application experience, the following key points for the establishment of application program are included: (1) The overlapping spectral peaks should be analyzed by full spectrum fitting method when there is interference to deduct or reduce the influence of interference peaks and to obtain the characteristic peak intensity of the target element; (2) In order to ensure the spectral fitting of Na-K, Mg-K, Al-K and Si-K, the Lα lines with same or similar positions should be removed from the spectral lines which participate in the fitting; (3) Elements with interference or mutual interference, such as As-Pb, Fe-Co, Ti-V-Ba, Fe-Mn and Mn-Cr, must be determined simultaneously under the same grouping conditions; (4) The rational use of filters is helpful to improve the signal-to-noise ratio and reduce the background value. The accuracy of determination results is greatly affected by background subtraction especially for low content elements; (5) The setting of parameter intercept at 0 after regression of calibration curve can effectively avoid the influence of impurities on the support film of standard sample on the subsequent sample detection results; (6) When there is a lack of particulate filter standards in the market, the results of different analysis techniques, different instrument testing, and comparison between many laboratories for the same particulate samples in filter media can effectively find out the problems in application program. The experiences in many years indicate that, the study and commercial product of simulated particulate matter standard on filter media and recalibration samples for light element X-ray fluorescence intensity in domestic is of great significance for effectively monitoring the intensity fluctuations, ensuring the consistency of sample test results at the same instrument and the comparability of test results of the same samples between different laboratories.