Concentration of Some Metal Ions Using 2-(5-Bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol and C18-Bonded Silica Gel

A simple and reliable concentration method of trace metals in aqueous solution is proposed. 2-(5-Bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol is used to form water-soluble metal chelates. The chelated metal ions are concentrated from dilute solution by adsorption onto a C18-bonded silica gel column. The adsorbed chelates are eluted with methanol and 1.0 mol dm-3 HCl and determined by ICP-AES or flame AAS. The proposed method is applied to the determination of heavy metal impurities in some commercial sodium salt reagents.