Naslov
Voltammetric determination of stability constants of lead complexes with C-vitamin

Autori
Branica, Gina ; Metikoš-Huković, Mirjana ; Omanović, Dario

Izvornik
Croatica chemica acta (0011-1643) 79 (2006), 1; 77-83

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

Ključne riječi
lead; L-ascorbic acid; voltammetry; stability constants

Sažetak
Interactions between lead and ascorbic acid were investigated by polarography and voltammetry. Applied techniques were: sampled polarography, differential pulse anodic stripping voltammetry, and square-wave voltammetry. The measurements were performed in perchlorate aqueous solutions under physiological ionic strength (0.15 mol dm^3). The electrochemical redox reaction of Pb(II) is reversible (without adsorption effects or interactions of other lead complexes e.g. hydroxides) under the following conditions: [Pb^2+] = 4x10^-7 mol dm^-3 and pH = 5.5. Ascorbic acid was gradually added from 10^-5 to 10^-1 mol dm^-3. After each increment of ascorbic acid, the signal of lead was recorded by square wave voltammetry. Stability constants were computed by applying a DeFord-Hume non-linear regression function F0 and after have performed a Levenberg-Marquardt fit with the Sigma Plot software. The apparent stability constants were calculated assuming a series of mononuclear complexes (MLn, n = 1, 2...) and yielding the following values for Pb(II)-ascorbate complexes: logβ _1=9.3&plusmn ; ; 0.2 and logβ _2=18.0&plusmn ; ; 0.1.

Izvorni jezik
Engleski

Znanstvena područja
Geologija, Kemija, Temeljne medicinske znanosti

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