Departmental Bulletin Paper ガラスビード法による蛍光X線分析装置(XRF)を用いた珪酸塩岩石の主・微量成分分析
Major and Trace Element Analysis of Silicate Rocks using Fused Glass Beads with an X-ray Fluorescence Spectrometer

外西, 奈津美  ,  安田, 敦  ,  中田, 節也

Quantitative analytical method was established for X-ray Fluorescence Spectrometer (XRF) using a fused glass bead of silicate rock powder diluted with lithium-tetraborate at a ratio of 1 : 5. It takes approximately 80 minutes to measure 10 major and 18 trace elements on one glass bead. Calibration lines constructed with 26 reference rock standards provide good accuracy and precision for elements with the exception of La. To confirm the quality of this analytical method, four reference rock standards (JA-2, JB-1 a, JG-1 a, and JR-2), which are not used for constructing the calibration lines, are measured as unknown samples. The analytical results agree well with recommended values. The stability of the instrument is evaluated by repeating measurements of the glass beads, JB-1 a and JG-1 a. The standard deviation of the results of 10 repeated measurements reveals fluctuations were below 0.02 wt. % for all major elements except SiO2. The standard deviation for SiO2 is slightly higher, i.e. 0.09- 0.12 wt. %, but the coefficient of variation for SiO2 is 0. 2%, which is small compared to other major elements. Analytical results for trace elements of the four reference rock standards agree well with their reported values, with the exception of Ba. Low precision and stability of Ba measurement derive from low X-ray intensity (L-spectrum) of Ba at the analytical conditions applied.

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