COMPLEX-FORMATION EQUILIBRIA IN IRON(III)-L-ALANINE SYSTEM

Complex formation in iron(III)-L-alanine solutions was studied by emf glass electrode and spectrophotometric measurements, in 0.5 mol dm-3 ( Na)NO3 medium, at 25-degrees-C. In the concentration range 0.5 less-th an-or-equal-to [Fe]0 less-than-or-equal-to 20.0, 5.0 less-than-or-equa l-to [Ala]0 less-than-or-equal-to 1000.0 (mmol dm-3) and 1.0 less-than -or-equal-to -log [H+] less-than-or-equal-to 3.5; {[Ala]/[Fe] = 10:1-1 00:1} the equilibria in the title system were explained by the model i ncluding the species FeHL, FeL, Fe(OH)L, Fe2(OH)2L2 (where HL denotes L-alanine) and several hydrolytic products. The stability constants of complexes are given. The mechanism of formation and structure of comp lexes in solution is proposed.