波长与能量色散复合型X射线荧光光谱仪测定海洋沉积物、水系沉积物、岩石和土壤样品中15种稀土元素

摘要

单独采用波长色散型X射线荧光光谱仪(WDXRF)或者能量色散型X射线荧光光谱仪(EDXRF)测定稀土元素时不仅存在谱线干扰问题,而且WDXRF分析稀土元素也存在灵敏度低的问题.为解决上述问题,实验采用粉末压片制样,使用最新型研发的波长与能量色散复合式X射线荧光光谱仪(WD-EDXRF)对海洋沉积物、水系沉积物、岩石和土壤样品中La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、Y 15种稀土元素进行测定.重点研究了波长色散和能量色散各自要分析稀土元素的测量条件.对于Dy、Eu和 T b使用分辨率高的WDXRF分析,其他12种稀土元素使用灵敏度高的EDXRF分析.采用45个海洋沉积物标样、水系沉积物标样、岩石和土壤标样,建立校准曲线.用经验系数法和散射线内标法校正基体效应,并用多元回归扣除稀土元素谱线重叠干扰.采用实验方法测定海洋沉积物、水系沉积物、岩石和土壤样品中稀土元素其检出限在0.01~2.8 μg/g之间,较WDXRF降低了约一个数量级.对水系沉积物标样 GBW07313进行精密度考察,各稀土元素测定结果的相对标准偏差(RSD,n=5)在0.10% ~6.1% 之间.对4类样品进行正确度考察,分析结果与认定值符合.%During the determination of rare earth elements by wavelength dispersion X-ray fluorescence (WDXRF)spectrometer or energy dispersion X-ray fluorescence spectrometer(EDXRF),the problem of spectral interference exists.Moreover,the sensitivity of WDXRF analysis is also low.In order to solve these problems,the sample was prepared by pressed powder pellet,and then 15 rare earth elements(in-cluding La,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Ho,Er,Tm,Yb,Lu and Y)in ocean sediment,stream sediment,rock and soil samples were determined by the recently developed wavelength dispersion-energy dispersion combined type X-ray fluorescence spectrometer.The measuring conditions of wavelength disper-sion and energy dispersion for analysis of rare earth elements were separately studied.For the determina-tion of Dy,Eu and Tb,the WDXRF analysis with high resolution were recommend,while EDXRF analy-sis with high sensitivity could be employed for the determination of other 12 rare earth elements.The cali-bration curves were established using 45 standard samples of ocean sediment,stream sediment,rock and soil.The matrix effect was corrected by empirical coefficient method and using scattered radiation as the internal standard.Moreover,the spectral overlapping interference of rare earth elements was deducted by multiple regression method.The rare earth elements in ocean sediment,stream sediment,rock and soil samples were determined according to the experimental method,and the detection limits were in range of 0.01-2.8 μg/g,which was about one order of magnitude lower than that of WDXRF.The precision test was conducted using the standard sample of stream sediment(GBW07313).The relative standard devia-tions(RSD,n=5)of measured results for rare earth elements were between 0.10% and 6.1%.The accu-racy was investigated using four types of samples,and the analytical results were consistent with the certi-fied values.