Spectrophotometric and Analogue Derivative Spectrophotometric Determination of Trace Zinc with 5, 10, 15, 20-Tetrakis(4-sulfophenyl)porphine in Presence of High Concentrations of Cadmium

摘要

On the basis of a fact that zinc(II) forms 1:1 complex with 5, 10, 15, 20-tetrakis(4-sulfophenyl)porphine [T(4-SP)P] rapidly at room temperature by metal-substitution in the cadmium-T(4-SP)P complex in neutral medium containing imidazole, a simple and practical method for the determination of small amounts of zinc in high concentrations of cadmium has been developed. The Soret band of the zinc complex at 425nm are used for the determination, its apparent molar absorptivity being 4.45×105l mol-1 cm-1. The method developed could successfully be applied to the determination of zinc in cadmium salts of guaranteed-reagent grade, without any preconcentration and prior separation. Further sensitization of the method by employing analogue derivative spectrophotometer is also described.