Nine intercomparisons of the determination of mercury present as impurity in different materials have been organised. 24 laboratories
in 10 different countries took part, mainly using activation analysis and atomic absorption techniques. The results show that
the reliability of the data produced and reported in this area leaves much to be desired, and that continuous control of the
quality of mercury analysis in the extremely low concentration range is essential.
The chemical aspects of isotopic fractionation in a multiple filament thermal ionization source were investigated. Samples
of uranium were loaded as nitrates, chlorides and sulphates. The dependence of measured isotopic ratios on the filament material
and the chemical form of the loading solution was studied. The dependence of the formation of uranium and its oxide ions on
various chemical and instrumental conditions were investigated using tungsten and rhenium filaments.