Results of Stability Tests on Reference Materials Being Stored by JSAC, JSAC 0302, JSAC 0311, JSAC 0401, JSAC 0501, JSAC 0602-2, JSAC PT0711 and JSAC PT0721

In Mar. ’06 to May ’08, the Japan Society for Chemical Analysis has operated stability tests on seven reference materials being stored by JSAC : JSAC 0302-river water for the analysis of inorganic components, JSAC 0311-wastewater for the analysis of dioxins, and so on. Interlaboratory comparison tests were performed with the participation of 6 laboratories for each reference material. In the tests, reference materials in storing were analyzed for the same components as in their certification or assignation. En numbers defined in ISO Guide 43-1 and En' numbers that derived from En were calculated from the test results and certified/assigned values in order to quantify the deviation of test results from the certified/assigned values. The stability of a reference material can be evaluated through the absolute value of its En' number. As a result, almost all results of stability tests of every reference material showed good relations with their certified/assigned values. Therefore, it was concluded that the reference materials tested here were stable.