Simultaneous determination of trace elements in soils and sediments by polarizing energy dispersive X-ray fluorescence spectrometry

Abstract

Possibilities of polarizing energy dispersive X-ray fluorescence (EDXRF) spectrometry were fully explored to materialize rapid trace element determinations of soil and sediment samples. The pressed powder pellet technique was adopted for sample preparation because of its simplicity. The trace elements examined were V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Sn, Cs, Ba, La, Ce, Pr, Nd, Pb, and Th. The instrument was calibrated by using 26 reference materials. Compton scatter radiation was used as an internal standard to compensate any matrix effects and operating characteristics of the instruments. The correlation coefficients of the calibration lines were greater than 0.98, with the exception of Co and Pr. The results obtained by the proposed EDXRF spectrometry were compared with those obtained by other methods for around 450 samples. Out of the 20 trace elements examined, the results for 10 elements (Ni, Cu, Zn, Rb, Sr, Nb, Cs, Ba, La, Ce and Nd) obtained by the proposed EDXRF spectrometry compared favorably with those determined through conventional wet chemical methods. In contrast, the results for 5 elements (Cr, Co, Zr, Sn, and Pr) exhibited poor agreements with those obtained by the chemical methods. Among these elements, poor agreements of Cr, Zr and Sn were attributable to incomplete dissolution and/or volatilization losses during chemical treatments based on an acid attack, and therefore we concluded that results obtained by EDXRF are superior over those by chemical methods. In the case of Co, however, overlapping of the Fe Kβ line is responsible for the lower correlation coefficient. Although the results of the other 4 analytes (V, Y, Pb and Th) 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 acid digestion pretreatments. © 2011 The Japan Society for Analytical Chemistry.