Characterization of SCR-DENOx materials by ICP-MS and ICP-AES: Comparison with XRF and NAA

A procedure for the determination of eleven macro constituents by ICP-AES and several trace elements by ICP-MS was developed to give quantitative accurate analytical information on a large number of ceramic catalyst samples used for the denitrification of flue gas from a power plant. The determination of macro and trace elements was done on the same solution derived from the lithium tetraborate (LTB) fusion of the sample. The accuracy of the proposed procedure was evaluated by analyzing the samples by X-Ray fluorescence (XRF) and by Neutron Activation Analysis (NAA). The results obtained by ICP-AES and XRF were compared by two different statistical models: the least squares linear regression (LR) and maximum-likelihood fitting of a functional relationship (MLFR). The examples reported in the present paper show that the application of an incorrect statistical model can lead to erroneous conclusions regarding the accuracy of the tested methods. The MLFR function assures the best fit for the experimental data allowing a realistic evaluation of the accuracy of all methods.