Rapid simultaneous multi-element determination of soils and environmental samples with polarizing energy dispersive X-ray fluorescence (EDXRF) spectrometry using pressed powder pellets

Abstract

A rapid simultaneous multi-element analysis method for soils and environmental samples has been established using polarizing energy dispersive X-ray fluorescence (EDXRF) spectrometry. The pressed powder pellet technique was adopted because it is simple and requires no specialized skills for sample preparation. The analytes examined were: Na2O, MgO, Al2O3, SiO2, P2O5, K2O, CaO, TiO2, MnO, Fe2O3, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Sn, Sb, Cs, Ba, La, Ce, Pr, Nd, Pb and Th. Twenty-six reference samples were used for the calibrations. Compton scatter radiation was used as an internal standard to compensate for variations in the sample matrix, particle size, packing density and operating characteristics of the instrument. The correlation coefficients of the linear regression lines were >0.98, with the exception of Na2O, MgO, Al2O3, SiO2, P2O5, Co, Pr and Nd. The values obtained using the proposed EDXRF spectrometry were compared with the values obtained using other methods. Out of the 31 analytes examined, the results for 12 compounds (CaO, K2O, TiO2, MnO, Fe2O3, Ni, Zn, Rb, Sr, Cs, Ba and Ce) obtained by the proposed EDXRF spectrometry compared favorably with those determined through conventional wet chemical methods. In contrast, the results for eight compounds (Na2O, MgO, Cr, Co, Zr, Sn, Sb and Pr) obtained by the proposed EDXRF spectrometry exhibited poor agreements with those obtained using chemical methods. Among these analytes, the poor agreements of Cr, Zr and Sn were attributable to incomplete dissolution and/or volatilization losses during the chemical treatments based on an acid attack. It can be concluded, therefore, that there is a high possibility of underestimating the concentrations of these elements if wet chemical methods are used. Although the results of the other 11 analytes were not as good as those of the first group, they still appeared to be of practical use, considering the time consuming and potentially hazardous wet chemical pretreatment.