Indirect complexometric determination of copper(II) using 1,10-phenanthroline as a sensitive masking reagent

An indirect complexometric method for the determination of copper(II) in the presence of other metal ions is described based on the masking ability of 1,10 phenanthroline towards copper(II). Copper(II) and other ions in a given sample solution are initially complexed with an excess of EDTA and surplus EDTA is titrated with lead nitrate solution using xylenol orange indicator at pH 5.0-6.0. Excess of 1% ethanolic solution of 1,10 phenanthroline is added and released EDTA from Cu(II)-EDTA complex is titrated against standard lead nitrate solution. Reproducible and accurate results are obtained for 4-50 mg of copper(II) with relative error of <0.3% and standard deviations equal to or less than 0.05mg. The method has been applied to the determination of copper(II) in its complex and alloys.