CHEMICAL SPECIATION OF Pb(II), Cd(II), Hg(II), Co(II), Ni(II), Cu(II) AND Zn(II) BINARY COMPLEXES OF L-METHIONINE IN 1,2-PROPANEDIOL–WATER MIXTURES

  • M. Padma Latha
  • V. Maheswara Rao
  • T. Siva Rao
  • G. Nageswara Rao School of Chemistry, Andhra University, Visakhapatnam-530 003, India
Keywords: Complex equilibria, Chemical speciation, L-Methionine, 1, 2-Propanediol, Metals

Abstract

Chemical speciation of Pb(II), Cd(II), Hg(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes of L-methionine in 0.0-60 % v/v 1,2-propanediol-water mixtures maintaining an ionic strength of 0.16 M at 303 K has been studied pH metrically. The active forms of ligand are LH2+, LH and L-. The predominant species detected are ML, MLH, ML2, ML2H, ML2H2 and MLOH. Models containing different numbers of species were refined by using the computer program MINIQUAD 75. The best-fit chemical models were arrived at based on statistical parameters. The trend in variation of complex stability constants with change in the dielectric constant of the medium is explained on the basis of electrostatic and non-electrostatic forces.
KEY WORDS: Complex equilibria, Chemical speciation, L-Methionine, 1,2-Propanediol, Metals

Bull. Chem. Soc. Ethiop. 2007, 21(3), 363-372.
Published
2007-11-26
Section
Articles

Journal Identifiers


eISSN: 1726-801X
print ISSN: 1011-3924