Chemical Speciation Of Binary Complexes of Pb(II), Cd(II) and Hg(II) With L-Dopa in Dimethylformamide-Water Mixture
Keywords:
L-dopa, dimethylformamide, MINIQUAD75, electrostatic forces, electrostatic forcesAbstract
Equilibrium study on complex formation of L-Dopa with Pb(II), Cd(II), and Hg(II) has been investigated pH metrically in dimethylformamide-water mixtures (0–60% v/v) at 303 K and 0.16 mol L?1 ionic strength. The predominant species detected for Pb(II) and Hg(II) are MLH2 and ML2H and those for Cd(II) are MLH, ML2H, MLH2. The appropriateness of experimental conditions was verified by introducing errors intentionally in the concentrations of ingredients. The models containing different numbers of species were refined by using the computer program MINIQUAD75. The best-fit chemical models were arrived at based on statistical parameters. The trend in variation of stability constants of the complexes with dielectric constant of the medium is attributed to the electrostatic and non electrostatic forces. The species distribution and the plausible equilibria for the formation of the species are also presented.
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