Iin this paper an isosbestic dual--wavelength spectrophotometric method for the simultaneous determination of zinc and cadmium using meso--tetrakis [4-(trimethylammonium) phenyl] porphine has been developed. The interference from excess of reagent was masked by adding lead ions solution.The molar absorptivities (Ae) for zinc and cadmium were 6. 54 × 105 and 4. 27 × 105 L. mol-1. cm-1,respectively. The method could be used to determine zinc and cadmium in synthetic mixtures, and the satisfied results were obtained.
