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Copper complexation by thiol compounds in estuarine waters
Laglera, L.M.; van den Berg, C.M.G. (2003). Copper complexation by thiol compounds in estuarine waters. Mar. Chem. 82(1-2): 71-89. hdl.handle.net/10.1016/S0304-4203(03)00053-7
In: Marine Chemistry. Elsevier: Amsterdam. ISSN 0304-4203, more
Peer reviewed article  

Available in  Authors 
    VLIZ: Open Repository 273732 [ OMA ]

Author keywords
    Copper; Thiol; Salicylaldoxime; Metal speciation; Estuarine waters

Authors  Top 
  • Laglera, L.M.
  • van den Berg, C.M.G.

Abstract
    The stability of copper complexes with thiol substances in estuarine waters was determined for the first time using a new procedure based on cathodic stripping voltammetry (CSV). The free thiol concentration was monitored during titrations with copper in the presence of a competing ligand salicylaldoxime (SA); concentrations of copper-complexing ligands and conditional stability constants were determined simultaneously but independently. The decrease in the free thiol concentration with increasing copper concentration was used as an independent measure of the thiol-complex stability. The conditional stability constant of the thiol complexes (log KCuThiol') was between 12.3 and 14.1, and decreased with increasing salinity. The copper complexing titrations were found to fit to two complexing ligands: L1 with concentrations between 10 and 33 nM, and L2 between 14 and 300 nM. The complex stability of most of the thiols was similar to that of CuL2. Titrations at different detection windows showed a shift in the thiol complex stability suggesting that a second thiol species was present. It is therefore possible that L1 is also a thiol species. The estimated thiol concentrations can account for up to half of the total ligand concentration at low to intermediate salinities and for all of the ligands at high salinities.

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