Sensitive and Reproducible Quantification of Cu2+ by Stripping with a Carbon Paste Electrode Modified with Humic Acid

• Published in: Journal of environmental science and health. Part A, Toxic/hazardous substances & environmental engineering Toxic/hazardous substances & environmental engineering, 2003-09, Vol.38 (9), p.1811-1823
• Main Authors: Thobie-Gautier, Christine, Lopes da Silva, Wilson T., Rezende, Maria O. O., El Murr, Nabil
• Format: Article
• Language: English
• Subjects: Anodic stripping; Carbon; Carbon - chemistry; Carbon paste; Cations; Copper; Copper - analysis; Electrochemistry; Electrodes; Environmental Monitoring - methods; Environmental Pollutants - analysis; Humic acid; Humic acids; Humic Substances; Modified electrode; Pastes; Reduction; Reproducibility of Results; Sensitivity and Specificity; Standard deviation; Voltammetry
• ISSN: 1093-4529; 1532-4117
• DOI: 10.1081/ESE-120022880

The preparation of a humic acid modified carbon paste electrode (HA-MCPE) as well as the behavior of its surface as complexing agent toward Cu 2+ 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 Cu 2+ 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 × 10 −8  − 10 −5  mol L −1 Cu 2+ and the relative standard deviation (R.S.D.) was 1.2% (n = 5) for [Cu 2+ ] = 1.6 × 10 −5  mol L −1 . 5 min accumulation time for [Cu 2+ ]>10 −7  mol L −1  and 10 min for [Cu 2+ ]