An accurate procedure for the determination of low levels of Iridium in Standard Reference Materials by neutron activation analysis

The paper describes a destructive neutron activation procedure especially set up for the determination of low levels of iridium. Only a few steps are required after irradiation, namely sample dissolution, noble metals adsorption on an ion-exchange column, removal of interfering radionuclides and counting. Successively iridium is removed from the column and the chemical yield evaluated. The method has been used for the determination of iridium in a large variety of standard reference materials, including materials of geological, biological and technological origin, with iridium levels ranging from about 0.005 to 18 ng/g. Results, given as the average of three or more independent analyses, and relative standard deviations, are reported and discussed. Average precision is about 8%, and the sensitivity is 0.004 ng.