Optimizing the immobilized dithizone on surfactant-coated alumina as a new sorbent for determination of silver

A simple and reliable solid-phase extraction method has been developed to selectively separate and preconcentrate trace amounts of silver ion from aqueous samples for subsequent measurement by atomic absorption spectrometry. Silver ion was adsorbed quantitatively from aqueous solution onto a column packed with dithizone (DTZ) immobilized on sodium dodecyl sulfate (SDS)-coated alumina. Optimum experimental conditions for adsorption of mug/ml levels of silver ions from aqueous solutions by the adsorbent have been reported. Surfactant aggregates were formed on alumina surfaces by mixing 100 mg of sodium dodecyl sulfate and 1.5 g of gamma-alumina in 50 ml water. The silver ions were quantitatively adsorbed by the sorbent over the pH range of 1.0-9.0 and were desorbed afterward with recoveries of >98% using thiourea as the eluent. A preconcentration factor of 100 was achieved. The procedure was applied for analysis of a real sample. Relative standard deviation (R.S.D.) was found to be 3.21%. (C) 2003 Elsevier B.V. All rights reserved.