Complexometric determination of palladium(II) using 2-mercapto propionyl glycine as demasking agent

A simple, rapid and accurate complexometric method for the determination of palladium(II) is proposed, based on the selective demasking property of 2-mercapto propionyl glycine (MPGH₂) towards palladium(II). In the presence of diverse metal ions, palladium(II) is complexed with excess of EDTA and the surplus EDTA is back titrated at pH 5-5.5 (acetic acid-acetate buffer) with standard zinc sulphate solution using xylenol orange as indicator. An excess of a 0.2% aqueous solution of MPGH₂ is then added to displace EDTA from Pd(II)-EDTA complex. The released EDTA is titrated with the same standard zinc sulphate solution as before. Reproducible and accurate results are obtained in the concentration range 2-22 mg of palladium with relative error of ±0.36% and coefficient of variation (n=6) not exceeding 0.31%. The effect of diverse ions are studied. The method is used for the determination of palladium in its complexes, catalysts and synthetic alloy mixtures.