RT journal article
T1 Determination of ultra-trace amounts of silver in water by differential pulse anodic stripping voltammetry using a new modified carbon paste  electrode
A1 El-Mai, Hafida
A1 Stitou, Mostafa
A1 Espada Bellido, Estrella
A1 García Vargas, Manuel
A1 Galindo Riaño, María Dolores
A2 Química Analítica
K1 Silver
K1 Speciation
K1 Differential pulse anodic stripping voltammetry
K1 Modified carbon paste electrode
K1 Mercury-free electrode
K1 water
AB A highly sensitive and selective new procedure for the determination of silver in aqueous media was developed using a modified carbon paste electrode (MCPE) by differential pulse anodic stripping voltammetry (DPASV). The modified electrode was based on the incorporation of 2-hydroxybenzaldehyde benzoylhydrazone (2-HBBH) in the carbon paste electrode. Silver ions were preconcentrated on the modified electrode at open-circuit by complexation with the ligand and reduced to zero valent at a potential of 0V, and followed by the reoxidation of adsorbed ions on to the electrode by scanning the potential in a positive direction. The oxidation peak of Ag (I) was observed at 0.2V (versusAg/AgCl). The analysis of Ag (I) was carried out in a cell containing the sample solution (20mL) buffered by 0.1molL 1K2HPO4/NaOH at pH 5.5 in aqueous solution and nitric acid (pH1) in real water samples. The optimumconditions for the analysis of silver include are duction potential of 0V and a pulse amplitude of 100mV, among others. The optimum carbon paste composition was found to be 14.1% (w/w) 2-HBBH, 56.2% (w/w) graphite powder and 29.7%(w/w) paraffin oil. Differential pulse anodic stripping voltammetric response was used as the analytical signal. Under the selected conditions, the voltammetric signal was proportional to the Ag(I) concentration in the range of 0.001–100 μg L 1 with favorable limits of detection and quantification of 1.1ngL 1 and 3.7ngL 1 after 3 min of accumulation time, respectively. By increasing the accumulation time to 10 min, detection and quantification limits can be further improved up to 0.1ngL 1 and 0.34ngL 1, respectively. In addition, the results showed a highly reproducible procedure showing a relative standard deviation of 1.5% for 12 replicate measurements. Many coexisting metal ions were investigated and very few interferences were found on the determination of Ag(I). Theproposed method was validated using certified reference estuarine waters (SLEW-3) with a relative errorof  1.3% and applied to the determination of silver ions in three river water samples collected fromGuadalquivir river (relative errors of þ3.4%, þ1.5% and  0.7%). Moreover,the method was successfullyapplied to the speciation analysis of total silver, free silver ions and silver nanoparticles in aqueous solutions. The results were in good agreement with those obtained by inductively coupled plasma mass spectrometry (ICP-MS).
PB Elsevier
YR 2016
FD 2016-01
LK http://hdl.handle.net/10498/20405
UL http://hdl.handle.net/10498/20405
LA eng
DS Repositorio Institucional de la Universidad de Cádiz
RD 13-nov-2026