Complexation, extraction and determination of the H(3)CHg(+) ion with cadion [1-(p-nitrophenyl)-3-(p'-azobenzene)-triazene].
The partition constants of Cadion, i.e., 1-(p-nitro-phenyl)-3-(p'-azobenzene)-triazene, of its complex with the methylmercuric ion, and of methylmercury chloride were determined in the system toluene/aqueous phase containing 40 vol.% methyl alcohol; they have the values of 4.3 x 10(3), 3.0 x 10(3), and 2.6 respectively. The reagent has an absorption maximum at 406 nm, whereas the methylmercury complex at 460 nm. The K(HR) value corresponding to the H(+) + R(-) right harpoon over left harpoon HR equilibrium is 10(10.85), HR being the reagent molecule and H belongs to the NH of the triazenic group (NNNH). The K(ext) value corresponding to the equilibrium H(3)CHg(+) + (HR)(o) right harpoon over left harpoon (H(3)CHgR)(o) + H(+) is 1.0, where the "o" indicates the species present in the organic phase. The reagent/H(3)CHg(+) combination ratio is 1/1. The formation constant of the methylmercury complex, K(H(3)CHgR), which corresponds to the equilibrium H(3)CHg(+) + R(-) right harpoon over left harpoon H(3)CHgR, has a value of 10(10.8) as estimated by means of two different methods. The IR spectra allowed some conclusions to be drawn concerning the formation of the complex. The complex is stable up to 180 degrees , and the reagent up to 140 degrees . The molar absorptivity is of 3.46 x 10(4) 1.mole(-1).cm(-1) and the H(3)CHg(+) can be determined in the range 0.025-4 ppm. The determination is highly selective.
Daneţ
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Department of Analytical Chemistry, Faculty of Chemistry, University of Bucharest, Bul. Republicii 13, Bucharest 70.031, Romania.
David
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