Indirect complexometric determination of cadmium(II) using 1,10-phenanthroline as selective masking agent

An indirect complexometric method is described for the determination of cadmium(II), 1,10-phenanthroline being used as masking agent. Cadmium(II) in a given sample solution is initially complexed with an excess of EDTA and the surplus EDTA is titrated with lead nitrate solution at pH 5.0–6.0 (hexamine), using xylenol orange as indicator. An excess of 1,10-phenanthroline is then added and the EDTA released from the Cd-EDTA complex is titrated with standard lead nitrate solution. Results are obtained for 1.5–57 mg of Cd with relative errors 0.90% and standard deviations 0.06 mg. Cu(II), Co(II), Hg(II), Ni(II), Zn(II), Pd(II), Tl(III), Au(III) and Sn(IV) interfere, but can be easily masked. The method is applied for the determination of cadmium in synthetic alloy solutions.