CERTIFIED REFERENCE MATERIALS FOR THE QUALITY-CONTROL OF EDTA-EXTRACTABLE AND ACETIC ACID-EXTRACTABLE CONTENTS OF TRACE-ELEMENTS IN SEWAGE-SLUDGE AMENDED SOILS (CRM-483 AND CRM-484)

The ecotoxicity and mobility of trace elements in soils are often eval uated through analytical results resulting from operationally-defined determinations (single and sequential extractions), e.g. based on EDTA , acetic acid etc, extractions. The significance and comparability of these results is highly dependent on the procedures used (standardized protocols or standards adopted by international bodies) and their qua lity control relies on the availability of reference materials certifi ed following these strictly applied procedures. Recognizing the need t o harmonize some of the extraction schemes currently used for soil ana lysis, the Measurements and Testing Programme (formerly BCR) has organ ized a series of interlaboratory studies, the first aim of which was t o evaluate EDTA- and acetic acid-extraction procedures and the second objective was to certify reference materials for their extractable tra ce element contents. Two sewage amended soils have been prepared for t his purpose, originating respectively from Scotland and Catalonia. Thi s paper describes the preparation, homogeneity and stability studies, and gives an overview of the certification campaign.