2009 Volume 95 Issue 1 Pages 59-64
Trace amounts of lead(II) in an iron-digested solution was derived to anionic iodo complex prior to being preconcentrated and separated from iron matrices by an ion-exchange adsorption/ion-pair elution method. Anionic lead(II)–iodo complex adsorbed on cotton impregnated with capriquat through ion-exchange interaction. The adsorbed lead(II)–iodo complexes could be eluted with methanol so as to be analyzed by graphite furnace atomic absorption spectrometry (GF-AAS). Iron matrices in the digested solution did not adsorb on the anion-exchanging cotton to be separated from lead(II) since iron ions reduced by iodide ion did not form stable anionic iodo complex. Satisfactory separation (more than 99.99%) of iron matrices and quantitative recovery of lead(II) could be achieved with the proposed preconcentration method. GF-AAS exhibited an excellent compatibility with the concentrate in analyzing lead(II) because GF-AAS can remove capriquat and iodide ion in the concentrate at a chirring stage. With 5-fold preconcentration GFAAS measurement allowed to determine trace amounts of lead in a digested solution of iron with a detection limit (3σ) of 5.3×10−9 mol/L, which corresponds to 0.11 μg/g in iron and steel. Lead contents in certified reference materials of iron and steel were successfully determined by GF-AAS combined with the proposed method.
