Naslov
Voltammetric determination of stability constants of iron(III) - glycine complexes in water solution

Autori
Cuculić, Vlado ; Pižeta, Ivanka ; Branica, Marko

Izvornik
Journal of electroanalytical chemistry (1572-6657) 583 (2005), 1; 140-147

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
iron(III)-glycine complexes; stability constants; voltammetry; water solution

Sažetak
Determination of the stability constants of dissolved iron(III) - glycine system in water solution (I = 0.6 mol L-1 in NaClO4, pH = 7.3 at 25+-1 oC) using differential pulse cathodic voltammetry (DPCV) and cyclic voltammetry (CV) was performed out on a static mercury drop electrode (SMDE). By choosing voltammetry as analytical tool, measurements with lower iron(III) concentrations (10-5 mol L-1), at the pH = 7.3 were enabled, which ensured the formation of higher coordination (1 : 2 and 1 : 3) complexes of iron(III) - glycine system. The added concentration of iron(III) ions was 2.5×10-5 mol L-1 and the concentrations of total glycine varied from 0.1 to 0.5 mol L-1. Since iron(III) reduction in glycine system, with the techniques employed, was found to be one-electron reversible process, it was concluded that this system contained labile iron(III) complexes. Thus, it was possible to determine stability constants. The stability constants of [Fe(Gly)2]+ and Fe(Gly)3 complexes, which had not been reported in the literature so far, were found to be log beta(23) = 17.21+-0.03 and log beta(33) = 20.19+-0.02, respectively. According to the constants found, chemical distribution of iron(III) in glycine water solution, as a function of pH, was calculated and proposed.

Izvorni jezik
Engleski

Znanstvena područja
Geologija, Kemija

POVEZANOST RADA