The updated IAEA database of natural matrix reference materials

The International Atomic Energy Agency (IAEA) maintains a database of biolo gical and environmental reference materials of natural origin (human and an imal tissues, foods, plants, soils, sediments, etc.) for trace elements, ra dionuclides, stable isotopes, organic contaminants and other related measur ands. The purpose is to help analysts to select reference materials for qua lity assurance purposes that match as closely as possible (i.e., with respe ct to matrix type and concentrations of the measurands of interest) the rea l samples that are to be analyzed. Former versions of this database were pr epared in co-operation with the United Nations Environment Programme (UNEP) , and provided as hardcopies free of charge. The latest version was from 19 95. More recently the database has been updated by the IAEA so that it now contains more than 22,500 values (mass fraction or concentration) for 660 d ifferent measurands and 1,705 reference materials developed by 56 producers from 22 countries. This paper gives an overview of the structure and conte nt of the database and of the two ways it may be browsed. Emphasis is given to reference materials that are intended to verifying analysis for radioan alytical measurements. The database is soon accessible on-line, cost-free, via the internet.