粉末压片-X射线荧光光谱法测定富硅土壤和沉积物样品中的5种重金属元素

X射线荧光光谱法测定土壤和沉积物中的重金属具有简便、快速、准确等优点，但现有的环境行业标准方法不适用于SiO2含量大于80%的土壤和沉积物。为提高X射线荧光光谱法测定土壤和沉积物中的重金属在环境监测领域中的适用性，建立基于粉末压片-X射线荧光光谱法测定富硅土壤和沉积物中重金属的分析方法。通过选取富硅的土壤和沉积物标准物质提高校准曲线的测量范围以及优化各元素的测量条件，探讨基体效应和谱线重叠干扰、研究压片制样的最佳压力等途径，测定富硅土壤和沉积物中的Pb、Cr、Cu、Ni、Zn。结果表明在已优化的测定条件下，通过延长校准曲线的测量上限，保证待测元素含量在校准曲线范围内，同时采用经验系数法和康普顿散射内标法校正基体效应，可进一步提高方法的准确度和精密度。方法比对结果显示该方法的测定结果与原子吸收光谱法的测定结果无显著性差异。选用2种不同的富硅标准物质进一步验证方法的精密度和准确度，Pb、Cr、Cu、Ni、Zn的测定结果与标准物质认定值的对数误差为0.002~0.08，相对标准偏差为1.0%~4.6%。该方法的精密度和正确度满足土壤和水系沉积物环境监测分析的技术要求，具有良好的应用前景。

Determination of 5 Kinds of Heavy Metal Elements in Silicon-rich Soils and Sediments by X-ray Fluorescence Spectrometry with Pressed Powder Pellet

X-ray fluorescence spectrometry has the advantages of simple, rapid and accurate determination of heavy metals in soils and sediments. However, the existing environmental standard method is not suitable for the determination of soils and sediments, when the content of SiO2 is more than 80%. In order to improve the applicability of determination of heavy metals in soils and sediments by X-ray fluorescence spectrometry in environmental monitoring, a method based on X-ray fluorescence spectrometry with pressed powder pellet was estabished for the determination of heavy metals in silicon-rich soil and sediment samples. Pb, Cr, Cu, Ni and Zn in silicon-rich soils and sediments were determined by selecting silicon-rich standard materials to improve the range of calibration curve, optimizing measurement conditions, discussing the correction of matrix and spectral line overlap interference, studying the optimal pressure of sample preparation. The results showed that under the optimized measurement conditions, the accuracy and precision of the method could be further improved by extending the measurement upper limit of the calibration curve to ensure that the content of the elements were within the range of the calibration curve, meanwhile the empirical coefficient method and compton scattering internal standard method were adopted to correct the matrix effect. There was no significant difference between the measurement results of this method and that of atomic absorption spectrometry. Two different silicon-rich standard materials were used to verify the precision and accuracy of the method. The logarithmic error between the measured results and the certified results of standard materials was 0.002~0.08 and the relative standard deviation was 1.0%~4.6%. The precision and accuracy of the method meet the analysis requirements of soil and stream sediment in environmental monitoring area, and has a good application prospect.