Chemical Speciation of Complexes of l-phenylalanine and maleic acid with toxic metal ions in Dimethylformamide -water Mixtures

The correction factor to be applied to the pH-meter dial readings was calculated with the computer program SCPHD [32]. By using the pH –metric titration data, the binary stability constants were calculated with the computer program MINIQUAD75, which exploits the advantage of the constrained least squares method in the initial refinement and reliable convergence of the Marquardt algorithm [33]. During the refinement of binary stability constants, pKw and the protonation constants [34] of L-phenylalanine and maleic acid were fixed.