MINISTRY OF AGRICULTURE, FISHERIES AND FOOD DIRECTORATE OF FISHERIES RESEARCH AQUATIC ENVIRONMENT PROTECTION: ANALYTICAL METHODS NUMBER 8 The Determination of Technetium-99 in Environmental Materials

As part of its responsibilities under various Acts of Parliament, MAFF Directorate of Fisheries Research has a duty to carry out a substantial programme of monitoring, surveillance and research in relation to the quality of the aquatic environment in and around the United Kingdom. In the course of that programme, a wide variety of methods of analysis are used for a wide variety of contaminants, both inorganic and organic, stable and radioactive. This series of publications describes the main methods used in the course of this work and parallels the existing Aquatic Environment Monitoring Report series, in which much of the resulting data is published. Regardless of whether the analytical procedure relates to a radionuclide or a non-radioactive contaminant, each report contains a step-by-step guide to analytical procedures and an explanation of the calculation of results. 6 7 separation and assaying of 99 Tc are thus important. The procedure described in this publication has been developed over a substantial period of time and has given excellent results in international intercomparison exercises. 2. ANALYTICAL TECHNIQUE Technetium is a member of group 7A in the periodic table and is the middle member of the triad manganese, technetium, and rhenium. As a member of the second transition series, it lies between molybdenum and ruthenium, but its chemical properties most closely resemble those of rhenium. As shown in Figure 1, both rhenium and technetium can exist in a large number of valency states but heptavalent and, to a lesser extent, tetravalent compounds are the most stable compounds. The other valencies are normally displayed only in conjunction with complexing ligands. Analytically, the ready oxidation of technetium