SPECIATION OF TERNARY COMPLEXES OF CALCIUM(II) AND MAGNESIUM(II) WITH L-ARGININE AND L-HISTIDINE IN MICELLAR MEDIA

摘要

A computer-assisted pH-metric investigation has been made on the speciation of complexes of Ca(II) and Mg(II) with L-arginine (Arg) and L-histidine (His).The titrations are carried out with sodium hydroxide in varying concentrations (0.5-2.5%,w/w) of surfactant-water mixtures at an ionic strength of 0.16 mol dm~(-3) and at a temperature of 303 K.Ca(II) and Mg(II) form the ternary complexes MLXH4,MLXH3,MLXH2 and MLX2H in surfactant-water mixtures.The effects of micelles,dielectric constant of the medium and the electrostatic interactions between the complex species on the stability of the complexes are discussed.Distribution diagrams and structures of the ternary complexes are also presented.