Comparison of differential pulse and alternating current polarography in the soft-modelling study of the complexation of Cd(II) by the fragment Cys-Gly and by the phytochelatin (gamma-Glu-Cys)2Gly.
A comparison of a differential pulse polarographic with a phase sensitive alternating current polarographic study of the Cd-Cys-Gly and Cd-PC(2) systems [PC(2) being a phytochelatin of general structure (gamma-Glu-Cys)(n)-Gly, with n = 2] has been performed. The chemometric multivariate curve resolution method with alternating least squares was applied in the experimental data analysis. The results obtained by both polarographic techniques have made it possible to find out the formation sequences of the complexes and their final stoichiometries. The alternating current polarograms compared with the differential pulse ones show some differences (a new signal and an important shift of peak potentials), which anyway are consistent with some of the conclusions obtained by differential pulse polarography. This fact implies that although the alternating current polarography results need some corrections before data treatment, they provide extra information that complements the conclusions achieved by differential pulse polarography.
Garrigosa
Anna Maria
AM
Departament de Química Analítica, Universitat de Barcelona, Martí i Franquès 1-11, 08028, Barcelona, Spain.
Ariño
Cristina
C
Díaz-Cruz
José Manuel
JM
Esteban
Miquel
M