Major element analysis of geological samples with wavelength Dispersive X-ray Fluorescence (WDXRF) spectrometry using glass disks and pressed powder pellets

Abstract

ABSTRACTA rapid and accurate method for total analysis of major elements in soils, sediments and rock samples has been established by wavelength dispersive X-ray fluorescence spectrometry (WDXRF) using fused glass disks and pressed powder pellets. Thirty geological standard reference materials were used for the construction of the calibration lines. Whereas the widely adopted devices for glass disk preparation were using a high frequency heating furnace and Pt dish for fusion as well as for casting, an electric furnace and Pt crucible were used in this experiment and the molten mixture was finally poured into Pt mold. Although this extended the time needed for disk preparation, the mixing of samples with the borate flux and the dissolution of samples were more complete in this method. The correlation coefficients of the linear calibration lines ranged from 0.9981 (SiO2) to 0.9999 (K2O and CaO). Linear regression analyses between the recommended and calculated values obtained by using the above calibration lines had revealed that the slope is very close to unity, with the exception of P2O5, and the intercept is negligibly small for all constituents. In contrast, the correlation coefficients of the calibration lines obtained by using the pellets ranged from 0.9595 (Al2O3) to 0.9989 (CaO). Despite of these somewhat disappointing results, however, the pellet method with WDXRF is still appeared to be an attractive technique for making rapid semi-quantitative determinations of elemental composition of samples, especially for K2O, CaO, TiO2, MnO and Fe2O3, when considering its easier pre-treatments and faster measurements.

Keywords

• Wavelength dispersive X-ray fluorescence spectrometry (WDXRF)
• geological samples
• major elements
• glass disks
• Inductively coupled plasma atomic emission spectrometry(ICP-AES)