Selective preconcentration of ultra trace copper(II) using octadecyl silica membrane disks modified by a recently...

A new simple and reliable method has been developed to selectively separate and concentrate ultra trace amounts of copper ion in aqueous samples for subsequent measurement by atomic absorption spectrometry (AAS). The Cu(2+) ions are adsorbed selectively and quantitatively during passage of aqueous solutions through octadecyl silica membrane disks modified with bis(2-hydroxyphenylamino) glyoxime. The retained copper ions then stripped from the disk with a minimal amount of 0.2M nitric acid solution as eluent, and determined by AAS. The proposed method permitted large enrichment factors of about 100 or higher. The limit of detection of the proposed method is 0.004ngml(-1). The maximum capacity of the membrane disks modified with 25mg of ligand was found to be 280+/-32mug of copper(II). The effects of various cationic interferences on the percent recovery of copper in binary mixtures were studied. The method was successfully applied to the recovery and determination of copper in several water samples.