A new synthesized sorbent, di (n-propyl) thiuram disulfide bonded on silica gel, was applied for separation and preconcentration of silver ion from aqueous samples. Factors influencing the sorption and desorption of silver ion were investigated. An aqueous solution containing sodium thiosulfate was used as eluent in order to selectively desorb the adsorbed silver ion from the surface of the sorbent. A preconcentration factor of 100 was achieved. The effect of coexisting ions in binary mixtures, containing silver ion and the foreign ion, on percent recovery of silver ion was investigated. Mercury(II) ion showed interfering effect. Separation selectivities for each metal ion of Zn2+, Cu2+, Co2+, Ni2+, Al3+, Hg2+, Ph2+, Ca2+, Cr3+, Mg2+, and Fe3+ were measured. The relative standard deviation under optimum conditions was 1.43% (n = 10). This system was applied for determination of silver ion in photographic waste and lakewater samples. (c) 2006 Published by Elsevier B.V.