నైరూప్య

Differential pulse polarographic determination of ultra trace nickel in natural waters after solid phase extraction

Mahmood Payehghadr, Mahsa Mirzaei

A highly selective and sensitive anodic stripping differential pulse polarographic method for determination of ultra trace amounts of Ni2+ ions in water samples is proposed. The method is based on the separation and preconcentration of Ni2+ on an octadecyl bonded silica membrane disk modified by a recently synthesized Schiff base, 2-((E)-(2-(2-(pyridine-2-yl) ethylthio) ethylimino) methyl)-4-bromophenol (PYTABr) at pH=7. The retained nickel on the membrane was eluted with 10 ml 0.1 M HNO3 and determined by anodic stripping differential pulse polarography. Extraction efficiency, influence of sample volume and eluent flow rates, amount of ligand, amount of eluent for elution of Ni2+ ions from membrane disk, pH, breakthrough volume and limit of detection have been evaluated. The effect of foreign ions on the percent recovery of heavy metal ions has also been studied. The limit of detection of proposed method for Ni2+ was found to be 3.2ng. L-1 and also an enrichment factor of 200were obtained. Themaximum capacity of the membrane disksmodified by 5 mg of PYTABr was found to be 325± µg Ni2+. The proposed method has been applied to the determination of nickel in several water samples with satisfactory results.