Simultaneous determination of zinc and mercury with 5,10,15,20-tetrakis(3-chloro-4-sulfophenyl)porphine by differential rate kinetics and flow injection analysis

A rapid and sensitive differential rate kinetic method for the simultaneous and sequential determination of zinc and mercury with 5,10,15,20-tetrakis-(3-chloro-4-sulfophenyl)porphine (m-Cl-TPPS₄) has been based on flow injection spectrophotometry. By proper stopped-flow of the merging zone, the metalloporphyrin complexes of zinc and mercury were simultaneously determined at the maximum absorbance wavelength of 425.7 nm with the proportional equation. The relative standard deviations for 1.0 g/ml zinc and 5.0 g/ml mercury with 100 l sampling volume were 0.43% and 0.62%, respectively, for 8 parallel determinations. The calibration graphs were linear over the concentration range 0–3.0 g Zn/ml and 0–12.0 g Hg/ml. The method has been applied to the analysis of synthetic water samples with satisfactory recovery.