Application of verification and validation procedures depending on the method used

Abstract

An ICP-AES method with Concentration Ratio Calibration (calibration in relative concentrations) makes it possible to improve significantly the metrological characteristics of certified reference materials (metals, alloys, technical and geological materials). The main reasons for this improvement are the advantages of the ICP-AES in combination with the advantages of the Concentration Ratio Calibration. The errors of sample weighting and the uncertainty of final volume, as well as the error attributed to the addition internal standard aliquot are excluded from the total error of analysis. Lithium hydroxide fusion in silver crucibles has been developed for the complete transfer of the ilmenite and zirconium concentrates, as well as Mg- and Cr- based refractories into solution. Compared with fusion with lithium metaborate in platinum crucibles, the proposed method is advantageous for a significantly lower cost of crucibles, higher solubility of the melt, and possibility of boron determination as an impurity in the analyzed materials. When certifying the reference samples, it is necessary to use the main principle of Concentration Ratio Calibration, i.e., the total amount of certified mass fractions and positive errors of the components to be determined should not exceed 100 % even when the ICP-AES method is not used. While conventional calibration methods use one-dimensional space and one-dimensional traceabihty the concentration ratio calibration works in re-dimensional space and provides higher accuracy of results due to n-dimensional traceabihty It is necessary to develop a theory of re-dimensional traceabihty which will provide a more reliable certification of reference samples in practice than the one-dimensional traceabihty that exists today.