US EPA

4808132 

Journal Article 

Interaction of cobalt(II), nickel(II) and zinc(II) with humic-like ligands studied by the ESI-MS and ion-exchange methods 

Kostic, I; Andelkovic, T; Andelkovic, D; Nikolic, R; Bojic, A; Cvetkovic, T; Nikolic, G 

2016 

1 

Journal of the Serbian Chemical Society
ISSN: 0352-5139
EISSN: 1820-7421 

81 

3 

255-270 

10.2298/JSC150917094K 

WOS:000375398500004 

The interactions of Co(II), Ni(II) and Zn(II) with humic acid and O-donor humic-like ligands were studied by the ion-exchange and electrospray ionization mass spectrometry (ESI-MS) methods. Interactions were confirmed by differences between the values of chromatogram peak areas for monocomponent (ligand) and binary systems (ligand with metal ion) by a newly developed ESI-MS 5 mu L-loop injection technique. The Schubert ion exchange method was used for the determination of the stability constants of the formed complexes at pH 4.0 and I = 0.01 mol dm(-3). Comparing the values of log K for complexes formed by di-positive metal ions with humic, benzoic and salicylic acids, it could be concluded that the interaction strengths of d-metals followed the Irving-Williams order: Co(II) < Ni(II) < Cu(II) > Zn(II). The obtained values of log K indicated that Pb(II) ions affect the strongest interactions with all the investigated ligands. Complexation of humic acids macromolecules possessing O-donor binding sites as major binding sites could be predicted and modeled following the same order of interaction strength as the Irving-Williams order. 

humic acid; humic-like ligands; heavy metals; ion exchange; ESI-MS