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Polarography and stripping voltammetry of metal–polycarboxylate complexes: Complexes of cadmium and zinc with polyacrylic and polymethacrylic acids
Author(s) -
DíazCruz José M.,
Ariño Cristina,
Esteban Miquel,
Casassas Enric
Publication year - 1991
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.1140030410
Subject(s) - polarography , chemistry , polyacrylic acid , anodic stripping voltammetry , zinc , cadmium , titration , stripping (fiber) , inorganic chemistry , adsorption , voltammetry , metal , ligand (biochemistry) , stability constants of complexes , analytical chemistry (journal) , ion , electrochemistry , electrode , chromatography , polymer , materials science , organic chemistry , biochemistry , receptor , composite material
Complex formation of Zn(II) and Cd(II) with polymethacrylic acid (PMA) and polyacrylic acid (PAA) is studied by sampled direct current, normal pulse, reverse pulse, and differential pulse polarography and by differential pulse anodic stripping voltammetry (DPASV). Titrations of Zn(II) or Cd(II) with partially neutralized PMA or PAA by DPASV allow the precise determination of the apparent formation constant K of the four systems. The two Zn(II) systems appear to be labile on the different time scales of the several techniques, without remarkable complications due to secondary phenomena. Their K values, determined by all techniques, agree satisfactorily. The two Cd(II) systems, and especially the Cd/PAA system, show rather involved behavior, which tends to normality when the degree of neutralization α n of the polycarboxylates increases. Both slow kinetics and ligand adsorption coupled with induced Cd(II) adsorption (evidenced by maxima on the normal pulse polarograms) seem to be present. For all α n values, DPASV yields higher estimates of K than do polarographic techniques.