Multi-element Determination in Geological Materials by Bench-top Polarized Energy Dispersive Xray Fluorescence Spectrometer Coupled with Direct Powder Sample Preparation

A benchtop type Polarized Energy dispersive X-ray fluorescence spectrometer coupled with direct powder sample preparation technique has been used to analyze silicate rocks, soils and sediments. About 50 elements can be simultaneously monitored, among which 20 elements (including K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, As, Rb, Sr, Y, Zr, Nb, Ba, Pb, Th) can be quantified in accordance with the regulation on mulitipurpose geochemical survey (1∶250000) issued by China Geological Survey and about 10 more elements can also be determined with less accuracy. Repeated sampling experiments showed that the analysis precisions for major elements were better than 2%(RSD) and mainly affected by sample preparation. For trace elements, the analysis precisions were generally better than 5%(RSD) and would be worse (up to 20%RSD) for very low concentrations. Generally, sample preparation contributed more than 50% to the total analysis variations. And this contribution increased with lower atomic numbers and higher concentrations. Different sampling mass would cause obvious result changes for such elements as Sn and Ba whose high energy K lines were used for measurements, but would not when sampling mass exceeded 1 g for elements with analysis line energies less than that of the Compton lines of Mo Ka which was used as the internal standard. Sampling mass need not be controlled if ensured to exceed 5 g. The method is suited for onsite geochemical analysis for its simplicity and its powerful measurement capability.