VALIDATION OF THE METHODS FOR HEAVY-METAL SPECIATION IN SOILS AND SEDIMENTS

The knowledge of the chemical farms of metals is used to assess their availability and uptake by plants, and in sediments the forms of metal s determine their transport and mobility in the aquatic media. This in formation may be obtained by determining chemical forms of metals (spe ciation) or different phases in which the metals are bound, obtained b y applying extraction schemes. The analytical methods used include dif ferent steps and all of them must be validated. We report here the rec ommendations to minimize the errors in this kind of analysis. For vali dation the use of Certified Reference Materials (CRMs) and the partici pation in inter laboratory exercises are highly recommended.