Quality assurance program for the chemical characterization of soils

A quality assurance program has been developed both to assess and to demonstrate the quality of the results produced by an analytical diagram applied to the chemical characterization of soils. The composition of several soils was determined following procedures based on the methods that are applied to silicate materials. A combination of acid decomposition followed by fusion allows the determination of SiO2, Al, Fe, Ca, Mg, Ti, P, Mn, Cd, Co, Cr, Cu, Ni, Pb and Zn; a specific acid attack was used for Hg analysis and an acid mixture decomposition to analyse Na, K, Li and Sr. Several quality control parameters, namely calibration function characteristics, limits of detection, limits of quantification, quality control standards, duplicate analysis, spike recoveries and certified reference materials analysis, are introduced, evaluated and discussed. The results obtained for the certified reference materials show that the analytical diagram gave acceptable accurate values for the elements applying the quality assurance program proposed.