绿松石成分的EDXRF方法研究

Study on EDXRF Method of Turquoise Composition

利用激光剥蚀电感耦合等离子体质谱仪(LA-ICP-MS)测试方法对来自湖北的26块表面相对干净、颜色均匀的绿松石样品进行定值,每个样品表面按照"田字格"的方式逐一测试9个点,用于评价绿松石成分的均匀性。数据结果显示,绿松石样品中Al,P,K,Cu,Fe,V,Cr和Zn的平均变异系数在5.4%以下,而CaO和SiO2的平均变异系数分别为34.8%和16.2%,说明绿松石中Si和Ca元素存在明显的不均匀性。选取其中的21个样品作为参考标准样品,5个作为未知样品,采用能量色散型X射线荧光光谱仪(EDXRF)建立绿松石的工作曲线,用于测定绿松石的成分。研究结果显示主量元素Al,P和Cu工作曲线的相关系数在92.3%~94.3%之间,平均相对误差在4.6%~9.7%;微量元素Fe,Cr和Zn的相关系数达到0.990以上,K和V元素工作曲线的相关系数分别为0.939和0.972,这五种元素平均相对误差范围在7.2%~13.9%;而Si和Ca元素工作曲线的相关系数分别为0.958和0.866,且在5个未知样品中,Si和Ca元素的平均相对误差分别为348%和27.8%,这与绿松石中Si和Ca元素的含量低和不均匀性,以及仪器方法的检出限等影响因素有关。重复性实验显示Al,P,Cu,Fe和Zn元素的相对标准偏差(RSD)均在1%以内,精密度较高;V,Cr,K,Ca和Si元素的RSD在1.34%~10.17%之间。该研究为快速、准确、无损地定量测定绿松石中Al,P,Cu,Fe,Cr,Zn,V和K等元素的含量提供了一种新思路和新方法,可运用于实验室的绿松石检测鉴定。

LA-ICP-MS was used to calibrate 26 turquoise samples with relatively clean and uniform color on each surface.We selected 9 points on each sample to test the homogeneity of their chemical composition.The results showed that the average error coefficients of Al,P,K,Cu,Fe,V,Cr and Zn in turquoise samples are below 5.4%,while the average error coefficients of CaO and SiO2 are 34.8% and 16.2% respectively,suggesting that the elements of Si and Ca in turquoise were heterogeneity.The turquoise working curve can be established by the energy dispersive X-ray fluorescence spectrometer（EDXRF）.We used 21 samples as the standard sample for reference and 5 as unknown samples to determine the composition of turquoise.Results showed that the correlation coefficients of Al,P and Cu of the main element are between 92.3% and 94.3%,with an average relative error of 4.6%-9.7%.The correlation coefficients of Fe,Cr,Zn micro-elements are more than 0.990,while the correlation coefficients of both K and V elements are 0.939 and 0.972.And the average relative error of those five micro-elements ranges from 7.2%to 13.9%.However,the correlation coefficients of Si and Ca are 0.958 and 0.866,the average relative error of which is 348% and 27.8%in the five unknown turquoise samples.The high average relative errors of Si and Ca may be influenced by the low content and the heterogeneity of Si and Ca in turquoise,also related to the detection limit of this instrument method.The repeatability test showed that the relative standard deviations（RSDs）of Al,P,Cu,Fe,Zn elements are within1%,suggesting that the accuracy of the test results is respectively high.While the RSDs of V,Cr,K,Ca,Si elements range from 1.34%to 10.17%.The study provides a new idea and method for determining the quantify of the elements of Al,P,Cu,Fe,Cr,Zn and V in turquoise quickly,accurately and losslessly,which can be applied to test and identify turquoise in laboratory.