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 th e 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 giv en sample solution are initially complexed with an excess of EDTA and surpl us EDTA is titrated with lead nitrate solution using xylenol orange indicat or 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 stand ard lead nitrate solution. Reproducible and accurate results are obtained f or 4-50 mg of copper(II) with relative error of <0.3% and standard deviatio ns equal to or less than 0.05mg. The method has been applied to the determi nation of copper(II) in its complex and alloys.