title: Copper speciation by competing ligand exchange method using differential pulse anodic stripping voltammetry with ethylenediaminetetraacetic acid (EDTA) as competing ligand.
abstract: A technique has been developed to study chemical speciation of copper in freshwaters by competing ligand exchange (CLE) method using anodic stripping voltammetry (ASV) in the differential pulse (DP) mode with ethylenediaminetetraacetic acid (EDTA) as a competing ligand. The voltammetric behavior of Cu(II)-EDTA complex has been investigated using DPASV. When DPASV is used at an appropriate deposition potential, the inert Cu(II)-EDTA complex becomes electroactive, and is reduced directly. Furthermore, at the same deposition potential, Cu(II)-fuvic acid and Cu(II)-humic acid complexes do not contribute significantly to the analytical signal, which makes EDTA a suitable competing ligand in the determination of copper speciation using CLE-ASV. This method has been applied to freshwater samples from Rideau Canal (Ottawa, ON, Canada). The analysis of the copper titration data of these freshwater samples has indicated the presence of a very strong copper-binding ligand with a conditional stability constant of approximately 10(20) and a corresponding very high concentration (above 100 nM) of the ligand.
authors.affiliation: Ottawa-Carleton Chemistry Institute, Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada.
authors.forename: Rong
authors.initials: R
authors.lastname: Wang
authors.forename: Chuni L
authors.initials: CL
authors.lastname: Chakrabarti
mesh_terms: D001667:Binding, Competitive; D002614:Chelating Agents / Q000737:chemistry*; D003300:Copper / Q000032:analysis*; D004492:Edetic Acid / Q000737:chemistry*; D004563:Electrochemistry; D004566:Electrodes; D004784:Environmental Monitoring / Q000379:methods; D005618:Fresh Water / Q000737:chemistry*; D007474:Ion Exchange; D008024:Ligands; D009864:Ontario; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D002614:Chelating Agents; D008024:Ligands; D003300:Copper; D004492:Edetic Acid