粉末压片-X射线荧光光谱法在地球化学标准物质均匀性检验中的应用研究

均匀性是标准物质三大特性之一。X射线荧光光谱法（XRF），精密度高，可实现多元素同时分析，是地球化学标准物质均匀性检验重要方法之一。目前，应用XRF对标准物质进行均匀性检验还存在争议。由于均匀性检验要求称样量为最小取样量，一般地球化学标准物质的最小取样量为0.1 g，而采用粉末压片-XRF进行均匀性检验时称样量为4 g左右，得到的结果在理论上不足以支撑样品在最小取样量条件下是否均匀。本研究改变了以往压片模具的大小，采用0.1 g样品粉末压片法制样，在对仪器条件进行优化的基础上，选取了3个土壤（GBW07425，GBW07428，GBW07388）和3个水系沉积物（GBW07375，GBW07378，GBW07379）标准物质，每个标准物质取15瓶，每瓶取样2份，共制样片30个，对SiO₂，Al₂O₃，TFe₂O₃，MgO，CaO，Na₂O，K₂O，Mn，Ti和P共10个主量组分进行了均匀性检验，根据单因素方差分析的F值、测定值的标准偏差（s）和相对标准偏差（RSD）综合判定样品的均匀性。通过理论计算，在样品照射半径为5 mm的条件下，所测10个主量组分的最小取样量小于0.1 g。0.1 g压片测定结果表明，本研究中的方法准确度高，相对误差小于16%，精密度高，相对标准偏差不超过4.3%，F值小于临界值，标准物质的均匀性良好。在最小取样量为0.1 g的条件下，应用X-射线荧光光谱法进行均匀性检验，不仅能够解决地球化学标准物质均匀性检验中长期存在的争议问题，还可为X-射线荧光光谱法在其他领域的应用提供技术支持。

Homogeneity Test of Geochemical Certified Reference Materials by X-Ray Fluorescence Spectrometry With Pressed-Powder Pellets

Homogeneity is one of the three characteristics of reference materials.X-Ray Fluorescence Spectrometry has lots of strengths,like simplicity,high precision,and multiple elements simultaneous analysis.So X-Ray Fluorescence Spectrometry is one of the important methods to test the homogeneity of reference materials.At present,the application of X-Ray Fluorescence spectrometry to test the homogeneity of reference materials is still controversial.The homogeneity test requires that the sample weight is the minimum,and the general geochemical reference materials minimum sample weight is 0.1 g.The sample weight is about 4 g when the XRF is used for the homogeneity test;the obtained result is theoretically insufficient to support whether the sample is homogeneous under the condition of the minimum sampling weight.Based on the optimization of instrument parameters,this study changed the size of the previous pelleting mold to make the sampling weight 0.1 g,using pressed powder pellets,selected three soil(GBW07425,GBW07428,GBW07388)and three stream sediment(GBW07375,GBW07378,GBW07379)certified reference materials,each reference material taken from 15 bottles,sampling 2 from each bottle,the number of the total samples is 30,choosing SiO₂,Al₂O₃,Fe₂O₃,MgO,CaO,Na₂O,K₂O,Mn,Ti and P 10 components to test.According to the single factor analysis of variance of F values and measured values of the standard deviation(S)and the relative standard deviation(RSD)comprehensive to evaluate the homogeneity of reference materials.Through theoretical calculation showed that the minimum sample weight of 10 main components was less than 0.1 g under the condition that the radiation radius of the sample was 5 mm.The results with 0.1 g pressed powder pellets showed that the accuracy of the method in this study was high,the relative errors were less than 16%,the precision was high,the relative standard deviations were no more than 4.3%,the F values were less than the critical values,and the homogeneity of soil and sediment certified reference materials was good.X-Ray Fluorescence Spectrometry is applied for determination under the condition that the minimum sampling amount is 0.1 g,which can not only solve the long-standing dispute in the homogeneity test of geological reference materials but also provide technical support for the application of X-Ray Fluorescence Spectrometry in other fields.