27 No. 1
Compilation of k0 and Related Data for NAA in the Form of Electronic Database (IUPAC Technical Report)
V.P. Kolotov and F. De Corte
Pure and Applied Chemistry
Vol. 76, No. 10, pp. 1921-1925 (2004)
This report describes the principles underlying a comprehensive electronic database that contains data essential for calculation of analytical results from neutron-activation analysis (NAA). The database is available through IUPAC. The method used is a comparator method called the k0 method, where k0 is a dimensionless factor that is experimentally measured with high accuracy for more than 130 isotopes and that makes use of the gamma spectroscopic line for an analyte isotope relative to a gold comparator. The database contains recommended values for k0 and other relevant nuclear data.
The conventional method of quantitative reactor neutron-activation analysis (NAA) is based on the relative method of standardization with the use of suitable reference materials. By optimal selection of reference materials, various interference effects (nuclear, measurement, etc.) may be neglected due to compensation. At the same time, the relative method of NAA has a number of restrictions: limited number of suitable reference samples, often nonoptimal for NAA with respect to concentration of the certified elements; difficulties in performing panoramic analysis; unavailability for determination of “unexpected” elements, etc.
To expand the versatility of NAA, standardless approaches based on mathematical modeling of all steps of analysis have been suggested and developed since the end of the 1960s. The “absolute” (parametric) method did not achieve broad popularity because of its inherent limitations, which led to lower accuracy. That is why attention was paid to the development of alternative comparator methods that combine the flexibility of “absolute” with the accuracy of relative standardization. The essence of a comparator method consists in co-irradiation of the analyzed samples with a suitable element of known mass (comparator), and combining this with the results of gamma-ray spectrometry. Various precalibrations and nuclear data enable one to compute the concentration of any element via the comparator.
The database is available in different file formats, such as Access97 and Access2000. The architecture of the database supports traceability of future data updating or appending, which implies easy recomputation of analytical data using any set of data, either the latest or previous one.
last modified 13 December 2004.
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