Validation method and uncertainty evaluation for determination of major and minor constituents in soils and sediments by WDXRF technique

The validation of analytical methods is a very important aspect for all the analytical chemistry activities and is also a basic requirement in the system of quality of a laboratory. In the method validation process is necessary to consider the all sources of uncertainty associated with the measurements. In this work, Na2O, Mg O, Al2O3, SiO2, P2O5, K2O, Ca O, MnO, Fe2O3, V, Cr, Co, Ni, As, Zn, Ga, Sr, Y, Pb and Zr in soils samples were determined by wavelength dispersive x-ray fluorescence technique (WDXRF). The statistical tests were applied for the validation of the fundamental parameters method. A procedure of the sample preparation in the powder pellets is presented, which one eliminate the sources of uncertainty proceeding from the weight, particle size, density and humidity. The accuracy of the method was evaluated by JB2, JP1 and JG1a geological certified materials from Geological Survey of Japan and Buffalo River Sediment, SRM 2704, from NIST. The results presented the Z-score values between -2 < z < 2 for all the elements, except for Na O determination, that presented a value between 3 < z < 3, proving the validity of the fundamental parameters method for soils and sediments analysis. (author)