地质样品中27项元素的粉末压片法x射线荧光光谱测定

DETERMINATION OF 27 ELEMENTS IN PRESSED POWDER PELLET SAMPLES OF GEOLOGICAL MATERIALS BY X-RAY FLUORESCENCE SPECTROMETRY

本文报导了用x射线荧光光谱法—次粉末压片制样同时测定Na. Mg. Al. Si.P. S. K. Ca. Ti. V. Cr. Mn. Fe. Co. Ni. Cu. Zn. Rb. Sr. Y. Zr. Nb. Ba. Hf. Pb. Th. U等27项元素的快速分析方法。从理论上提出了新的基体效应学校正模式,首次引入了非荧光分析的物质(筒称NFAM)的新概念;并计算了理论α系数,使理论α系数在粉末压片法x射线荧光分析中获得了应用。本方法测定的对象可以是岩石,土壤和水系沉积物等地质样品。

In this paper, a. method of X-Ray Fluorescence Analysis(XRFA) for accurately and rapidly determination of 27 major, minor and trace (Na, Mg, Al, Si, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Y. Zr, Nb, Ba, Hf, Pb, Th, U) elements in samples of geological materials was studied. We derived the calculation formulas of theoretical Alpha coefficients of multi-clement system. Matrix effects for the analysis of major and minor elements were corrected by using theoretical Alpha coefficients calculated by us with D · J model in the XR-14 AN and UP Software. In order to obtain better analytical results, we introduced, first in XRFA field, NFAM theory. A matrix correction component, which is called as 'Non-Fluorescence Analysis Material' (NFAM) was introduced into the calculation method of the theoretical Alpha coefficients, NFAM component is consists of binder, ignition loss (CO2, H2O) and materials not analysed by XRFA(F-.Cl-and so on). Matrix effects for the analysis of the trace elements were corrected by using Compton Scattering and empirical Alpha coefficients obtained from regression analysis by DJ model. Background corrections of the analysis of the trace elements are also very important, so we introduced the Two-Stcp Background Correclion(TSBC) theory and method. When using TSBC theory, background measurements became unnecessary, so this method could decrease time of measurement. All the samples analysed were prepared in form of pressed powder pellets, which were made of 2.0 g of sample powder (250-300 mesh) and 1.0 g of microcrystalline cellulose, carefully mixed and homogenized in agate mortar and pressed at 15-20 ton for 1 min. Pressed powder pellets were analysed by PHILIPS PW1400 automatic XRF Spectrometer with On-Line computer P851(32K). The optimun determination conditions were selected experimentally. Using this method, we determined international geochemical reference samples from Canada and Japan and domestic geochemical reference samples, and obtained very good results. The accuracy, pricision and determination limit of this method were satisfactory, therefor, this method is very suitable to rapidly copmrehensive analysis for the major, minor and trace elements in geological and geochemical materials.