Determination of copper in seawater based on a liquid membrane preconcentration system

Abstract

A new method to determine the concentration of copper in seawater has been developed. It was based on the use of a bulk liquid membrane (BLM) system to separate and preconcentrate the copper ions, allowing the use of a very simple and common analytical technique as flame atomic absorption spectroscopy (FAAS). The liquid membrane consisted of an organic solution containing di-(2-ethylhexyl)phosphoric acid (DEHPA) in kerosene. The chemical optimization of the preconcentration system was performed by using the modified simplex method. Under optimum conditions, the preconcentration yield for real samples was 76.21%, copper preconcentration factor being 4.30. The reliability of the new method was confirmed by analyzing several real seawater samples, with copper concentrations ranging between 2.5 and 5 μg l −1 , previously analyzed by a well-established technique. For these real samples, the average relative error of the determination was 9.96%, while relative standard deviation averaged 0.33%.