INDIRECT COMPLEXOMETRIC DETERMINATION OF PALLADIUM(II) USING SODIUM-NITRITE AS A SELECTIVE MASKING REAGENT

A selective complexometric method is described for the determination of palladium, sodium nitrite being used as masking reagent. Palladium(II) in a given sample solution is initially complexed with an excess of EDTA and the surplus EDTA is titrated with zinc sulfate solution at pH 4.5-5.5 (acetic acid-sodium acetate buffer), using xylenol orange as indicator. An excess of sodium nitrite is then added, the mixture is shaken well and the EDTA released from the Pd-EDTA complex is titrated with a standard zinc sulfate solution. Results are obtained for 2.5-27.5 mg of Pd with relative errors less than or equal to 0.5% and standard deviations less than or equal to 0.05 mg. The interferences of various ions are studied. The method is applied for the determination of palladium(II) in alloys and complexes.