Quantitative electron probe microanalysis of metallic oxide mixtures applying an empirical calibration technique

Abstract

An analytical procedure is proposed for the independent quantitative chemical analysis of each element in the presence of other elements in the matrix of a sample by Energy Dispersive Electron Probe Microanalysis. For this purpose, an empirical calibration technique (which we shall call here the JABO method), which studies the variation of the X-ray intensities in terms of the analyte concentration in a chemical system with a complex matrix, is established. The methodology consists of the modification of the unknown sample by addition of a diluent, an internal standard and the analyte itself (dilution-addition method). A mathematical model is proposed to calculate the K parameters for the analyte ( K i) and standard ( K p) in each sample. A series of glass discs for each analyte are prepared which make it possible to obtain experimental values of characteristic X-ray lines. Some new K parameters are defined as K i and K p quotients, which remain constant in a wide concentration range. This allows us to use them for the calculation of the component concentrations of the unknown sample, as reproducing mathematical expressions between X-ray intensity and analyte concentration are obtained. An algorithm is proposed to calculate the component concentration in a sample with a complex matrix where components exist with a strong interelemental interaction effect. The method has been applied satisfactorily to the determination of titanium (accuracy 3%) and zinc (accuracy 0.5%) in the presence of a large proportion of zirconium which acts as interferent.