title: Sensitive and reproducible quantification of Cu2+ by stripping with a carbon paste electrode modified with humic acid.
abstract: The preparation of a humic acid modified carbon paste electrode (HA-MCPE) as well as the behavior of its surface as complexing agent toward Cu2+ cations are described. Electrochemical studies of the reduction of the complexed cations and of the anodic stripping oxidation of the resulting copper are outlined. The anodic stripping current was correlated to the Cu2+ concentrations. A well-defined method for the preparation of reproducible electrodes is described. The effects on the current response obtained by cyclic voltammetry of the humic acid ratio, the pH, the accumulation time, and the speed scan rate were studied. Calibration graphs were linear over the range 3 x 10(-8)-10(-5) mol L(-1) Cu2+ and the relative standard deviation (R.S.D.) was 1.2% (n=5) for [Cu2+] = 1.6 x 10(-5) mol L(-1). 5 min accumulation time for [Cu2+] > 10(-7) mol L(-1) and 10 min for [Cu2+] < 10(-7) mol L(-1) were sufficient to permit sensitive and reproducible measurements. The electrode was successfully used to measure Cu2+ in real samples and the results were compared to those obtained by the standard method with differential pulse anodic stripping voltammetry.
authors.affiliation: Groupe Electrochimie-LAIEM-Faculté des Sciences et des Techniques, Université de Nantes, Nantes, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Thobie-Gautier
authors.forename: Wilson T Lopes
authors.initials: WT
authors.lastname: da Silva
authors.forename: Maria O O
authors.initials: MO
authors.lastname: Rezende
authors.forename: Nabil
authors.initials: N
authors.lastname: El Murr
mesh_terms: D002244:Carbon / Q000737:chemistry; D003300:Copper / Q000032:analysis*; D004563:Electrochemistry; D004566:Electrodes; D004784:Environmental Monitoring / Q000379:methods*; D004785:Environmental Pollutants / Q000032:analysis*; D006812:Humic Substances; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D004785:Environmental Pollutants; D006812:Humic Substances; D002244:Carbon; D003300:Copper