The renovated silver ring electrode in determination of lead traces by differential pulse anodic stripping voltammetry

摘要

The study of a new type of working electrode - the renovated silver ring electrode (RSRE) -for lead ions detection via differential pulse anodic stripping voltammetry (DP ASV) without removal of oxygen is reported.The only four constituents of the RSRE:a specially constructed silver ring electrode,a silver sheet used as silver counter/quasi-reference electrode and a silicon O-ring,are fastened together in a polypropylene body.The renovation of this electrode is carried out through mechanical removal of solid contaminants and electrochemical activation in the electrolyte which fills the RSRE body.Excellent repeatability and reproducibility - also in organic samples solutions - were reached in a period of a few weeks through the renovation of the electrode surface before each measurement.The reduction and stripping of lead on silver electrode under the DP ASV conditions are underpotential deposition/dissolution phenomena.The RSRE is used for the determination of Pb ions in concentrations ranging from 1 x 10~(-9) to 1 x 10~(-7) M.The repeatability of DP ASV runs in synthetic solutions covering the entire concentration range is better than 2%.Obtained calibration curves are represented by a correlation coefficient of at least 0.999.The detection limit (LOD) for the time of electrodeposition equal to 60 s is 0.2 x 10~(-9) M.LOD for Pb~(2+) detection at the RSRE is similar to this reported for a rotating silver electrode in subtrac-tive anodic stripping voltammetry (E.Kirowa-Eisner,et al.,Anal.Chim.Acta,385 (1999) 325).The analysis of Pb~(2+) in synthetic solutions with and without surfactants,certified reference materials and natural water samples have been performed.