ABSTRACT

In this article mixed ligand complex formation equilibria of copper(II) and zinc(II) with isoniazid and two amino acids have been determined by potentiometric titration method, involving the use of Irving Rossotti procedure. The formation constants of mixed ligand complexes have been found to be Cu(II)-isoniazid-L-asparagine logK= 7.29; Zn(II)- isoniazid-L-asparagine logK= 4.09 and Cu(II)-isoniazid-L-glutamic acid logK= 6.70; Zn(II)- isoniazid-L-glutamic acid logK= 6.30, at 25.0±0.1° C and I= 0.11 mol dm-3 ionic strength (NaCIO4) in aqueous solution. The maximum values of the conditional formation constants were found to be in accordance with the mixed-ligand complex formation constants in a given pH region. In addition, the mole fractions of different species from mixed complexes were calculated by means of formation constants.