TRACE-METAL PRECONCENTRATION WITH SULFONATED AZO-DYES AND ICP AES DETERMINATION

The preconcentration of trace elements, namely Ca(II), Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Mn(II), Ni(II), Pb(II), Pd(II), Pd(IV) and U(VI), by complexation with sulphonated azo-dyes and retention on an ion-exchange resin was studied. Cu(II) was chosen as a reference metal ion and its uptake efficiencies with 11 different azo-dyes investigated as a function of experimental parameters such as acidity, ligand concentration etc. The different behaviours are explained in terms of the structure of each ligand. Some of the ligands were subsequently tested with the other metal ions. Two different procedures (ligand in solution or immobilized on the resin) and the effects of interfering agents were also evaluated.