CERTIFIED REFERENCE MATERIALS FOR SPECIFIC CHEMICAL FORMS OF ELEMENTS

The determination of specific chemical forms of elements is highly necessary for the understanding of biogeochemical pathways of elements in the environment or for the assessment of their toxic impact. As a consequence, a number of chemical species have been included in the list of substances to be monitored in the frame of EU legislation and the number of determinations, as carried out in routine and research laboratories, has increased considerably in recent years. High accuracy of analytical results is a prerequisite for good interpretation of data, but this is far from being achieved in speciation analysis. Various means exist to ensure the accuracy of analytical data, among which the participation in interlaboratory studies (leading to comparison with the results of other laboratories) and the use of certified reference materials (CRMs) are two key aspects, In this paper, attention is mainly paid to the role of CRMs for quality control of determinations of specific chemical forms of elements. Examples of CRMs currently available for speciation analysis are presented, in particular fish tissues certified for their content of methylmercury and sediment reference materials certified for their content of butyltin species.