QUANTITATIVE ELECTRON-PROBE MICROANALYSIS OF METALLIC OXIDE MIXTURES APPLYING AN EMPIRICAL CALIBRATION TECHNIQUE

An analytical procedure is proposed for the independent quantitative c hemical analysis of each element in the presence of other elements in the matrix of a sample by Energy Dispersive Electron Probe Microanalys is. For this purpose, an empirical calibration technique (which we sha ll call here the JABO method), which studies the variation of the X-ra y intensities in terms of the analyte concentration in a chemical syst em with a complex matrix, is established. The methodology consists of the modification of the unknown sample by addition of a diluent, an in ternal standard and the analyte itself (dilution-addition method). A m athematical model is proposed to calculate the K parameters for the an alyte (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 experi mental 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 con centration range. This allows us to use them for the calculation of th e component concentrations of the unknown sample, as reproducing mathe matical expressions between X-ray intensity and analyte concentration are obtained. An algorithm is proposed to calculate the component conc entration in a sample with a complex matrix where components exist wit h a strong interelemental interaction effect. The method has been appl ied satisfactorily to the determination of titanium (accuracy 3%) and zinc (accuracy 0.5%) in the presence of a large proportion of zirconiu m which acts as interferent. (C) 1997 Elsevier Science B.V.