Determination of Silver by Flame Atomic Absorption Spectrometry after Preconcentration on Naphthalene Modified with Dithizone

A solid-phase extraction method for preconcentration of silver and consequent determination by atomic absorption spectrometry is described. The method is based on the adsorption of silver on naphthalene modified with dithizone in a column. The adsorbed silver is eluted from the column with a thiourea solution and determined by flame atomic absorption spectrometry. The adsorption conditions including pH, reagent concentration, eluent volume, flow rate and interfering ions were investigated. The calibration graph was linear in the range 10-1000 ng mL(-1) of Ag in the initial solution with r = 0.9998. The limit of detection based on 3S(b) was 3.9 ng mL(-1). The relative standard deviation for ten replicate measurements of 40 and 600 ng mL(-1) of Ag was 4.4% and 0.9%, respectively. The method was applied to the determination of silver in mineral, radiology film and wound dressing samples.