Improvement of the empirical regression type algorithm, based on the well-known canonical form equation by Lachance, for calculations of chemical element concentration and its applications for XRF expressanalysis to control and manage the technological processes on mine manufactures, are considered.

Despite the criticism of regression-type algorithms, because they have no physical sense, they are used successfully in the software of xray quantometers and energy dispersive spectrometers at different plants when it is necessary to analyze the samples with slightly varied matrix for the concentration of the elements of interest very rapidly (2-3 minutes for full analysis of one sample) and with high accuracy (-1% relative error in weight).

Our task was to improve the so-called physics of the algorithm to get the required analytical stability and to account for the random factors which influence measured intensities unexpectedly (heterogeneity of analyzed sample, roughness of its surface, etc.).

The results of the investigations were applied to the samples of apatit-nephelin manufacture. Together with successful solution of the problem, new analytical possibilities for classification of samples according to their mineralogical differences were obtained.

The new XRF empirical regression type algorithm was realized in special software.

The scattering of the primary X-ray tube spectrum on a low Z material in 90°-geometry produces polarised excitation radiation, which clearly decreases the background of fluorescence spectra in Cartesian geometry (Barkla excitation). Several publications have shown the advantages of this excitation mode in comparison with both direct excitation and secondary target excitation.

In the current work an attempt was made to apply the fundamental parameter method to the analysis of boron, oxygen, fluorine and heavier components of silica glasses. Experimental results are presented and compared with calculations based on theoretical work. The specimens consist of sets of certified standards which were obtained from Breitlahder company, Germany.

Furthermore, it is shown that the match between the certified compositions and fundamental parameter computations is affected by the quality of available fundamental parameters for the ultralight elements as well as by the underlying mathematical models. Especially in quantitative analysis of these elements, a large variety of secondary enhancement effects must be taken into account. Two major mechanisms have been considered in the presented computations: excitation by fluorescence photons emitted from aiJ available excited atoms, and excitation by photoelectrons ejected after the primary ionization event. Their magnitude exceeds that of the conventional energy region by far and thus uncertainities in the corrective algorithms have a large effect,

Geometrical effects occur when primary x-rays irradiate a mineral inclusion which lies close to the boundary between it and a surrounding mineral having a different chemical composition. An investigation of one of these near-edge effects was performed in the case when x-ray microfluorescence is applied for analysis. Analytical mathematical expressions were developed to correct for this effect and were tested exper imentally.

Several calibration methods and empirical formulae have been developed so far for analyzing materials quantitatively in XRF spectrometry. Many of them require reference samples to determine the relationship between the characteristic intensities of the elements and their concentrations. In order to eliminate empirical and semiempirical procedures, the fundamental parameter method (FPM) has been developed, which is one of the most helpful evaluating tools in quantitative XRF analysis. Some interpretations of this approach have the advantage that no standard samples are needed. The simultaneous application of FPM and polychromatic excitation demand an exact mathematical description of the primary spectral distribution as well as the efficiency function of the detector system.

Nowadays x-ray fluorescence analysis is one of the major techniques for determination of trace elements. Vacuum operated Si (Li) .energy-dispersive x-ray spectrometers can analyze simultaneously up to 50 elements from Na (Z=11) to U (Z = 92) . Proper interpretation of the accumulated spectra requires correct solution of x-ray line overlap problems. In many cases knowledge of x-ray intensity ratios can make the procedure for resolving the overlapped peaks more reliable and reproducible. Measurements of radiative transition rates can also provide fundamental tests of theoretical atomic structure calculations. There are many other useful applications of x-ray emission rates in theoretical and experimental physics. On the other hand, there are differences in the published data, which suggests that x-ray intensity ratios are still not known with the necessary accuracy, and new measurements are useful and necessary.

We are engaged in a study of the ash produced by combustion of lignite in a 750-MW power station. The aim is to follow the transport of elements with Z> 16 from the mine, through: a) the combustion process, b) emissionto the atmosphere or c) deposition in a land fill, d) transport in the environment and e) subsequent uptake by animals and humans. The resulting data will be used to estimate potential adverse impact on human health caused by operation of the power station.

XRF has become over the years a method of choice when dealing with elemental analysis of large quantities of samples. Geochemical analysis pushes the technique to its limits because of the large number of samples to be analysed as well as the lower limits of detection required for many trace elements of geochemical and economic importance. The Analytical Geochemistry Group at the British Geological Survey (BGS) has access to a wide variety of methods for instrumental analysis. Instrumental methods for inorganic analysis include x-ray fluorescence as well as DC arc emission spectrometry, atomic absorption spectrometry, inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). X-ray fluorescence, however, is the technique of choice when it comes to the routine analysis of large numbers of solid samples. The XRF section at BGS currently runs three sequential spectrometers (one PW1480 and two PW2400s made by Philips Analytical X-Ray). In this paper, some aspects of the method of sample preparation and the calibration of the spectrometers for the analysis of the trace elements are discussed.

Nowadays personal computers [PCs) have sufficiently high speed of calculation and large memory and can be used for precise modeling and implementation of the fundamental parameter methods in the x-ray fluorescence (XRF) analysis. Because of its low price the PC is generally a standard component of energy-dispersive and wavelength-dispersive x-ray fluorescence analyzers, and allows not only automation and control of the whole spectrometer during the scientific experiments or routine analysis, but also complete on-line calculation of concentrations {using sophisticated calibration models), QA/QC monitoring, and archivation of the data. Together with the development of faulti-task operation systems for personal computers the efficiency of their use became higher. A few years ago the main requirement for the software was that it be optimized in order to perform many sophisticated calculations in as short time as possible, and less attention was paid to the interface “computer-user”. Now, with much more powerful new generation PCs, one of the main requirements on the software for XRF analysis is to be “user-friendly”, i.e. not to require special education and extended learning period before using it and to ensure high flexibility of application of the programs.

The electron beam furnace is a nearly ideal tool to conduct on-line analysis of molten metal. In the process of melting the metal with a high intensity electron beam, x-rays are created. A wave-length dispersive x-ray spectrometer, specially designed for this environment, has been used to analyze the composition of the molten metal. This significantly reduces the time required to determine the concentration of critical elements in the melting process.

Many of the operational problems encountered in the utilization of coal can be attributed to the inorganic constituents in coal. These problems depend upon the quantity and association of the inorganic components in the coal, the combustion conditions, and the combustion or gasification system, geometry. Thus the mineral concentrations and organie associations within a coal must be determined to predict the properties and behavior of the inorganic constituents of coal during combustion and utilization.

XRF nondestructive sample analysis is very convenient when applied to samples that should not be altered, for example, works of art or archeological pieces. When one has various similar samples of this characteristic, a good sample comparison method is necessary. There are various comparison methods among which the three component graphic representation allows a comparison in a throe element component. In an XRF analysis, a large number of peaks, representing emissions from K and L lines normally appear. When a well calibrated spectrum is provided, the determination of the elements in the samples is relatively simple. However, accuracy is difficult to acheive when results from many samples are to be compared.