A MODEL FOR THE CALCULATION OF THEORETICAL INTENSITIES IN X-RAY-FLUORESCENCE OBTAINED BY THE LIMIT DILUTION METHOD AND FOR THE ELIMINATION OF THE MATRIX EFFECT

The correction factors obtained via the limit dilution method (LDM) as the operating mode are defined. A simple mathematical model is used t o obtain equations for the calculation of the correction coefficients H, M, Y and Y/H from experimental measurements of the sample's fluores cence intensity, measured at two different dilutions. The model can be used to calculate the theoretical fluorescence intensity for any dilu tion, which, when applied, shows and justifies the decreased matrix ef fect when dilution is increased; this facilitates the choice of the op timum degree or real dilution for a given matrix error. This paper pro poses an algorithm for the calculation of the analyte concentration in samples with a complex matrix. The method is applied to the determina tion of calcium and iron in silicoaluminates. The results obtained sho w satisfactory accuracy with a theoretical dilution factor f = 0.05.