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...

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.