SPECTROPHOTOMETRIC DETERMINATION OF MERCURY WITH ,10,15,20-TETRAKIS(3-CHLORO-4-SULFOPHENYL)PORPHINE BY FLOW-INJECTION ANALYSIS

,10,15,20-tetrakis(3-chloro-4-sulfophenyl)porphine (m-Cl-TPPS4) was sy nthesized and used for the spectrophotometric determination of mercury by flow injection analysis. A pseudo-first-order reaction kinetic mec hanism was proposed with a rate constant of 0.8 min-1 for Hg(II) with m-Cl-TPPS4 in the presence of 8-hydroxyquinoline in a medium of 1.0 M acetic acid and sodium acetate buffer solution (pH 6.22). In the optim um conditions of reaction temperature (85-degrees-C), stopped-flow tim e (60 s) and sampling volume (100 mul), the method's relative standard deviation was 0.82% (n = 12) at 5.0 mug ml-1 mercury, with a linear r ange of 0-12.0 mug ml-1 and an analytical frequency of 60 h-1. The det ection limit (3sigma) was 0.025 mug ml-1. Interference studies showed that most metal ions co-existing with Hg'' could be tolerated at 100-f old excess levels, but Zn2+, Cu2+ and Mn2+ needed to be masked. The me thod has been applied to the analysis of water samples with satisfacto ry results.