[Determination of trace platinum, palladium, gold and rhodium in geological samples by ICP-AES after preconcentration by diphenlthiourea immobilized on aluminum oxide].

A method for the determination of Au, Pt, Pd and Rh by ICP-AES after preconcentration on a column containing diphenylthiourea immobilized on aluminum oxide was developed. The optimum acidity of solution, amount of adsorbent, elution solution, flow rate and volume of the samples were obtained for the elements studied. The effect of interfering ions on the recovery of the analytes was also investigated. Under the optimum measuring conditions, the recoveries were found to be between 95%-105%. The detection limits of Au, Pd, Pt and Rh was 0.0085, 0.022, 0.015 and 0.022 microgram.g-1, respectively, and the relative standard deviation was lower than 5%. This procedure was applied to the determination of Au, Pd, Pt and Rh in geological samples.