The cyclic renewable mercury film silver based electrode for determination of Uranium(VI) traces using adsorptive stripping voltammetry

The new cyclic renewable mercury film silver based electrode (Hg(Ag)FE), applied for the determination of uranium(VI) traces using differential pulse adsorptive cathodic stripping voltammetry (DPAdCSV) is presented. The Hg(Ag)FE electrode with a surface area adjustable from 1.1 to 12 mm(2) is characterized by very good surface reproducibility (<= 2%) and long-term stability (more than 2 thousand measurement cycles). The mechanical refreshing of mercury film is realized in the simple constructed device, in a time shorter than 1-2 seconds. The effects of various factors such as: preconcentration potential and time, pulse height, step potential and supporting electrolyte composition are optimized. The calibration graph is linear from 0.4 nM (95 ng L-1) to 250 nM (60 mu g L-1) for an accumulation time of t(acc) = 20 s, with correlation coefficient of 0.9996. For a Hg(Ag)FE with a surface area of 2.7 mm(2) the detection limit for an accumulation time of 120 s is as low as 12 ng L-1. The repeatability of the method at a concentration level of the analyte as low as 2.4 mu g L-1, expressed as RSD is 2.5% (n = 7). The proposed method was successfully applied and validated by studying the recovery of U(VI) from spiked river water and sediment samples.