CRM-601, A STABLE MATERIAL FOR ITS EXTRACTABLE CONTENT OF HEAVY-METALS

Sequential extraction schemes provide information on the mobility of h eavy metals from polluted sediments. The lack of uniformity of these s chemes, however, does not allow results to be compared nor the procedu res to be validated. In 1987 the Community Bureau of Reference, (BCR, now Standard, Measurements and Testing Programme) of the European Comm ission launched a programme to harmonise single and sequential extract ion schemes for soils and sediments. As a result certified reference m aterial CRM 601 (lake sediment) was prepared and certified for the ext ractable contents of some trace elements, following a standardised seq uential (three-step) extraction procedure. In order to verify the long -term stability of the material an intercomparison exercise was design ed with the participation of eight expert laboratories. The results co nfirm the stability of the extractable contents of Cd, Cr, Ni, Pb and Zn in this type of material, and demonstrate that the preparation of t his kind of CRM can be achieved.