Voltammetry assisted by multivariate analysis as a tool for speciation of metallothioneins: competitive complexation of alpha- and beta-metallothionein domains with cadmium and zinc.
Multivariate Curve Resolution by Alternating Least Squares (MCR-ALS) is applied to voltammetric data obtained in the study of competitive complexation of Zn(II) and Cd(II) by alpha- and beta-domains of metallothionein (MT). The application of MCR-ALS allows the estimation of both the voltammograms and the concentration profiles associated with each electrochemical process. The complexity of the voltammograms obtained in titrations of the alpha- or beta-domains of MT with Cd(II) and later Zn(II) (or vice versa) prevents their direct interpretation using traditional electrochemical methods. But when MCR-ALS is applied, voltammograms can be interpreted rather satisfactorily in both qualitative and quantitative terms. MCR-ALS showed the formation of Cd2Znbeta dom and Cd3Znalpha dom complexes when both metals were competitively added. A method based on the combined use of voltammetry and some chemometric techniques is proposed. It can be useful for the metal speciation of environmentally relevant natural ligands.
López
María José
MJ
Departament de Química Analítica, Facultat de Química, Universitat de Barcelona, Av. Diagonal 647, E-08028 Barcelona, Spain.
Ariño
Cristina
C
Díaz-Cruz
Silvia
S
Díaz-Cruz
José Manuel
JM
Tauler
Roman
R
Esteban
Miquel
M
D002104:Cadmium / Q000737:chemistry*; D004563:Electrochemistry; D004784:Environmental Monitoring / Q000379:methods; D004785:Environmental Pollutants / Q000032:analysis*; D008024:Ligands; D008668:Metallothionein / Q000032:analysis / Q000737:chemistry*; D015999:Multivariate Analysis; D015032:Zinc / Q000737:chemistry*
D004785:Environmental Pollutants; D008024:Ligands; D002104:Cadmium; D008668:Metallothionein; D015032:Zinc