Computer augmented modelling studies of Pb(II), Cd(II), Hg(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes of L-glutamic acid in 1,2-propanediol-water mixtures

• Main Authors: Vegi Rao Maheswara, Muddapu Latha Padma, Tirukkuvalluri Rao Siva, Gollapalli Rao Nageswara
• Format: Article
• Language: English
• Published: Serbian Chemical Society 2008-01-01
• Series: Journal of the Serbian Chemical Society
• Subjects: chemical speciation; l-glutamic acid; 1,2-propanediol; bioavailability; metals
• Online Access: http://www.doiserbia.nb.rs/img/doi/0352-5139/2008/0352-51390812169V.pdf

Chemical speciation of Pb(II), Cd(II), Hg(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes of L-glutamic acid was studied at 303 K in 0-60 vol. % 1,2-propanediol-water mixtures, whereby the ionic strength was maintained at 0.16 mol dm-3. The active forms of the ligand are + LH3, LH2 and LH-. The predominant detected species were ML, ML2, MLH, ML2H and ML2H2. The trend of the variation in the stability constants with changing dielectric constant of the medium is explained based on the cation stabilizing nature of the co-solvents, specific solvent-water interactions, charge dispersion and specific interactions of the co-solvent with the solute. The effect of systematic errors in the concentrations of the substances on the stability constants is in the order alkali > > acid > ligand > metal. The bioavailability and transportation of metals are explained based on distribution diagrams and stability constants.