Preconcentration of trace amounts of silver ion in aqueous samples on octadecyl silica membrane disks modified with hexathia-18-crown-6 and its determination by atomic absorption spectrometry

摘要

A simple and reliable method has been devel-oped to selectively separate and concentrate trace amounts of silver ion from aqueous samples for the subsequent measurement by atomic absorption spectrometry. Ag~ ions are absorbed quantitatively during passage of aque-ous samples through an octadecyl-bonded silica mem-brane disk modified by hexathia- 1 8-crown-6. Almost all matrix elements will pass through the disk to drain. The retained Ag~ ions are then stripped from the disk with a minimal amount of thiosulfate solution as eluent. The pro-posed method permitted large enrichment factors of about 200 and higher. The limit of detection of the proposed method is 50 ng Ag~ per 1000 mL. The effects of various cationic interferences on the recovery of silver in binary mixtures were studied. The method was applied to the re-covery of Ag~ ions from different synthetic and water samples.