Ternary complex formation between Nickel(II)-Dipicolinic acid with small blood serum bioligands

With a view to obtaining information about the formation of the Nickel(II) ternary complexes with Dipicolinic acid (H2Dipic) and the low molecular mass components of the blood serum (Lactic acid (HLac), Oxalic acid (H2Ox), Citric acid (H3Cit) and phosphoric acid (H3PO4)), the potentiometric measurements using a glass electrode have been carried out in aqueous solution with the experimental conditions (25 °C, 1.0 mol dm− 3 NaCl) and at different ligand to metal molar ratios. Computer-assisted analysis of the potentiometric titration data yielded equilibrium constants for the systems studied. Several different complexes were separately considered during the calculation procedure, but evidence was found only for the mononuclear species. Speciation calculations based on the determined constants were done.