ASV determination of cadmium complexation in seawater. Methodology evaluation.
The methodology for using DPASV to study cadmium complexation in seawater is evaluated using EDTA as a model ligand and by analysing natural samples. The results show that the methodology gives an accurate evaluation of metal complexation when inert complexes are studied, both as regards the ligand concentration and the conditional stability constant; the error for both the parameters is lower than 10% at a ligand concentration of about 10(-8) M and a conditional stability constant of 10(9) M-1. Cadmium complexes with ligands present in natural seawater show an evident kinetic lability that may lead to underestimation of the conditional stability constant when a working electrode characterised by a very thick diffusion layer is used. The conditional stability constant in one water sample of the Adriatic coast ranged between 0.14 and 1.4 l/nmol using a rotating disk electrode at rotation rates of 300 and 6000 rpm. The results of cadmium complexation obtained for samples collected in coastal seawater show that the ligands present low specificity for the metal.
Capodaglio
Gabriele
G
Dipartimento di Scienze Ambientali, Università Di Venezia Ca' Foscari, Calle Larga S. Marta, 2137-30123 Venezia. capoda@unive.it
Toscano
Giuseppa
G
Barbante
Carlo
C
Gambaro
Andrea
A
Scarponi
Giuseppe
G
Cescon
Paolo
P
D002104:Cadmium / Q000737:chemistry*; D004492:Edetic Acid / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D008628:Mercury / Q000737:chemistry; D012623:Seawater / Q000737:chemistry*
D008024:Ligands; D002104:Cadmium; D004492:Edetic Acid; D008628:Mercury