Anodic stripping voltammetry of lead and cadmium without deliberately added electrolytes has been studied at uttrasmall carbon-ring electrodes following In situ deposition of mercury. The stripping of lead has been studied In detail to Investigate the dependence of stripping peak current on experimental parameters such as potential scan rate, preconcentratlon duration, deposition potential, concentration of Hg+ during deposition, and concentration of Pb2+. Anodic stripping voltammetry In solutions without deliberately added supporting electrolyte avoids problems associated with Impurities Introduced when electrolyte Is added. These impurities appear to be highly Important when Pb2+ analysis is carried out in dilute solutions. In addition, a unique effect Is observed when relatively low concentrations of Hg+ (1.0 × 10-6 M) are used for the In situ deposition step. When low Hg+ concentrations are used, the stripping current does not decrease as rapidly as expected as the concentration of Pb2+ is reduced. The slope of the log-log plot of peak current vs Pb2+ concentration is significantly less than unity, but the calibration plot is linear, and the resulting enhanced peak currents at low Pb2+ concentrations make stripping analysis possible at extremely low concentrations. Concentrations as low as 3.2 × 10-11 M of Pb2+ have been examined.
|Number of pages||6|
|Publication status||Published - 15 Dec 1990|