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Abstract  

An emission-transmission method in X-ray fluorescence analysis, based on theoretical considerations, has been applied for eliminating matrix effects due to variations in the chemical composition of samples. The measurements have been carried out in so-called compact geometry, using153Gd source of the primary radiation and a NaI(Tl) crystal (3″ in diameter, 2 mm thick). The element to be determined was antimony in a CaCO3 matrix with various admixtures of CuO. A method of semitheoretical construction of nomograms has been introduced for the evaluation of the measurements. Six variants of the method are discussed, and a criterion permitting to find the most useful variant is given. The theoretical considerations have been confirmed by the experiments.

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Abstract  

A way of graphical estimation of sensitivity is presented for the following methods: a)  X-ray fluorescent analysis without the elimination of matrix effects, b)  fluorescence-Compton-scattering method, c)  dilution method. The influence of several parameters on the sensitivity has been considered, such as the concentration of the element to be determined, chemical composition of the sample, the ratio of the energy of primary radiation to the energy of fluorescent radiation, geometry of the measurement, chemical composition of the diluent, and the degree of dilution.

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Abstract  

A theoretical model of the enhancement effect in non-dispersive X-ray analysis is proposed. The considerations relate to a point source and detector localized in the same place (which is an approximation of the conditions of compact geometry). The results obtained in this work are different from those of other authors. Possibilities are suggested for the elimination of the influence of the enhancement effect on the results in non-dispersive X-ray fluorescence analyses.

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Abstract  

Measurement of the intensities of the characteristicsK-series radiation of calcium and iron has been used for the elimination of the influence of iron on the calcium determination in cement raw mix. Two methods of interpretation of the experimental results are given, using nomograph or so-called ‘generalized’ calibration curve. The results are explained theoretically. The results of chemical analyses of industrial samples have been compared with non-dispersive fluorescence analysis.

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Abstract  

Theoretical consideration concerning some possibilities for the elimination of matrix effects in non-dispersive X-ray fluorescence and absorption analysis are discussed. The theoretical treatment is concerned with the following methods: (a)  double-channel absorption edge analysis, (b)  concentration increase and dilution method in fluorescence analysis, (c)  fluorescence-absorption method, (d)  emission-transmission method, (e)  fluorescence-Compton scattering method, (f)  method of multicomponent analysis. On the basis of the derived formulas, nomographic methods of interpretation of the data are given. Using these methods it is possible to determine unambiguously the concentration of the relevant element. The formulas are also convenient for numerical interpretation. The introduction of the concept of “generalized sensitivity” allows the comparison of various radiometric methods.

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Conclusions  

(i)  The introduction of the concept of “generalized sensitivity” enables us to compare several composite analytical radiometric methods. (ii)  The concept of generalized sensitivity makes calculations of the relative error easier for a given a.r.m., when curvilinear nomographs are used for the interpretation of the results.

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Abstract  

Fast determination of calcium in cement raw mix is a very important problem from the economic point of view. In order to solve this task, the following two methods are proposed: (i) Non-dispersive X-ray fluorescence analysis (using109Cd as a source of primary radiation); (ii) back-scattering of β-particles (using90Sr+90Y as a source). The influence of the following factors has been studied in both methods: (i) concentration of iron in the matrix; (ii) water content; (iii) grain size of the sample. The influence of the energy of the primary radiation on the slope of a calibration curve has been analyzed in the fluorescence method. In the concentration range of 42–52% CaO, the absolute standard error is 0.17% CaO in the fluorescence analysis, and 0.5% CaO for the method of back-scattering of β-particles. The average time of a determination is about 2 min.

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Abstract  

Theoretical considerations and experimental data are presented concerning the influence of the energy of the primary radiation on the sensitivity of X-ray fluorescence analysis. An additional criterion in selecting the energy of the primary radiation based on the relative sensitivity of X-ray fluoresence analysis depends on the energy of the primary radiation and it becomes higher with the increase of this energy.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
H. Vogg
,
H. Braun
,
R. Löffel
,
A. Lubecki
,
A. Merz
,
J. Schmitz
,
J. Schneider
, and
J. Vehlow

Abstract  

The works done by the “Laboratorium für Isotopentechnik” of the Nuclear Research Centre, Karlsruhe, is discussed in the field of the application of radioisotope techniques in chemistry and chemical engineering.

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