CERTIFIED REFERENCE MATERIALS FOR SPECIFIC CHEMICAL FORMS OF ELEMENTS

The determination of specific chemical forms of elements is highly nec essary for the understanding of biogeochemical pathways of elements in the environment or for the assessment of their toxic impact. As a con sequence, a number of chemical species have been included in the list of substances to be monitored in the frame of EU legislation and the n umber of determinations, as carried out in routine and research labora tories, has increased considerably in recent years. High accuracy of a nalytical results is a prerequisite for good interpretation of data, b ut this is far from being achieved in speciation analysis. Various mea ns exist to ensure the accuracy of analytical data, among which the pa rticipation in interlaboratory studies (leading to comparison with the results of other laboratories) and the use of certified reference mat erials (CRMs) are two key aspects, In this paper, attention is mainly paid to the role of CRMs for quality control of determinations of spec ific chemical forms of elements. Examples of CRMs currently available for speciation analysis are presented, in particular fish tissues cert ified for their content of methylmercury and sediment reference materi als certified for their content of butyltin species.