The significance of very accurate RNAA methodos for quality assurance and certification of candidate reference materials

摘要

The reliability of results of inorganic trace analysis produced by various laboratories is often far from adequate, as demonstrated by several international comparisons. Hence there is a need for methods with 'guaranteed' accuracy which could be used to check the accuracy of routine analytical methods, and for certification of the candidate reference materials. General principles for the construction of such methods employing radiochemicla neutron activation analysis (RNAA) are presented. The basic approach involves the combination of neutron activation with selective and quantitative post-irradiation isolation of the indicator radionuclide by column chromatography, followed by gamma ray spectrometric measurement. Several criteria were formulated to decide when the analytical result may be acknowledged as having been obtained by a 'definitive' or 'very accurate' method. The importance of such methods for quality assurance is emphasized and illustrated by several examples. Definitive methods for the determination of copper and cobalt in biological materials as well as very accurate methods for the determination of cadmium, nickel, molybdenum and uranium in similar matrices are briefly described.