Applicability of potentiometric stripping analysis to the speciation of lead–humic acid complexes using potassium permanganate as oxidant

Suitability of Stripping Chronopotentiometry for Heavy Metal Speciation Using Hydrogen Peroxide as Oxidant: Application to the Cd(II)-EDTA-PMA System

“…Finally, when compared to the previous results with KMnO 4 [16], the use of H 2 O 2 as oxidative reagent seems to introduce stronger perturbations in the potential data. However, H 2 O 2 has the advantages of not introducing additional metallic species like Mn(II), Mn(III) or Mn(IV) and of a quite lower oxidation power, which reduces the risk of oxidizing ligands present in the sample.…”

“…This is why Hg(II) or the less popular Fe(III) or Ce(IV) [14,15] have not been considered (Hg-, Fe-and Ceions can displace the analyzed metal from their complexes). Taking into account the promising results obtained by Soares et al [16] using KMnO 4 in the SCP study of some Pb(II) complexes, the research of additional suitable oxidants has been focused in another "anionic" reagent such as K 2 Cr 2 O 7 , already used for nonspeciation studies [17], and also in "non metallic" oxidants like O 2 or H 2 O 2 . It must be noted that in the case of K 2 Cr 2 O 7 (in a similar way as for permanganate), the eventual interference of Cr(III)-ions resulting from dichromate reduction should not be discarded.…”

Electrochemical Processes of Cadmium, Copper, Lead, and Zinc in the Presence ofN-(2-Hydroxyethyl)piperazine-N ′-3-Propanesulfonic Acid (HEPPS): Possible Implications in Speciation Studies

“…In fact, I p lower than I p0 can be due to other factors than adsorption; formation of labile complexes with diffusion coef®cients lower than that of the free metal ion or of inert complexes [21] and occurrence of surface concentration effects [27,28] also provoke reduction of the peak current. The formation of labile complexes with diffusion coef®cients lower than that of the free metal ion seems also not probable because in another work [29], we con®rmed that the diffusion coef®cients of lead labile complexes, whose ligands are simple structures as HEPPS, were equivalent to the diffusion coef®cient of the free metal ion. 1).…”

Chemistry of metal–humic complexes contained in Megalopolis lignite and potential application in modern organomineral fertilization

“…It is interesting that Pb is one of the most abundant metals in the alkaline extract. Soares et al (1998) reported that Pb readily interacts with commercially available humic acids. Lishtvan et al (2005) showed that the association between Pb 2+ and humic matter derived from reedsedge and high-moor grass peats was found to occur not only via bonding of metal cations to functional groups of humic acids but, also, via bonding of additional amounts of cations to the surface of colloidal aggregates.…”