| 概要 |
Analytical techniques for X-ray fluorescence analysis for 9 trace elements (Zr, Y, Sr, Rb, Zn, Cu, Ni, V and Ba) in silicate rocks were investigated by using fused rock samples. The method to make gla...ss disks was the same as that developed for major element analysis (NAKADA et al., 1985). The disks were made from 1 g of a powdered rock sample, 5 g of flux (Li_2 B_4 O_7) and about 30 mg of lithium bromide. To make standard samples for the calibration, pure chemical reagents of trace elements were diluted by flux, and, then, mixed with synthetic rock sample which was also made from chemical reagents. X-ray intensity of a trace element is proportional to its concentration and inversely proportional to the mass absorption coefficient of the glass disk. Background intensities at 2θ=17° and 33° of glass disks were found to be a function of the mass absorption coefficients. This relation was used for the estimation of the mass absorption at a wavelength of X-ray radiated from a trace element. This method is effective for the elements with the absorption edges shorter than Fe-Kα. Glass disks of various compositions, but without any interference of spectral lines, were prepared to estimate interference effects of spectral lines (Sr-Kβ on Zr-Kα, Rb-Kβ on Y-Kα, Br-Kβ on Rb-Kα, Ti-Kα on V-Kα, and Ti-Kα on Ba-Lα). Although the intensity of Y-Kα was corrected twice for spectral interference of Br-Kβ and Rb-Kβ, the correlation between the intensity and the concentration is good, as well as for the other trace elements. The detection limits are about 10 ppm for most trace elements. The analytical results of inter-laboratory geochemical standards are in good agree with their recommended values.続きを見る
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