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The fractionation of Cd, Cu, Mo, Ni, and Zn species in extracts of rye (cv. Fernando) seedlings (grown up in both standard and Cd2+-enriched medium) and rye flour was performed by SEC/ICP-MS method. The majority of Cu, Zn, and Ni in all samples were bound in the 1-2 kDa fraction. Molybdenum occurred in all samples in the fraction of 3 kDa. During five days of cultivation in a solution of 30 µmol/l Cd2+, the plants accumulated as much as 5 mg/kg fresh matter of Cd, but its soluble portion represented only 12-15%. The prevailing portion of Cd complexes was contained in the fraction of 3 kDa, while the minor part occurred in the fraction of 20 kDa. The speciation of elevated Cd in plants differs from that of other metals present at a physiological level. The metal-rich fractions of the extracts of all samples (i.e. those of 1-2 kDa) were refined by immobilised metal affinity chromatography. The isolated ligands of trace elements were peptides rich in dicarboxylic aminoacids.