Refreshable mercury film silver based electrode for determination of chromium(VI) using catalytic adsorptive stripping voltammetry.

The refreshable mercury film silver based electrode Hg(Ag)FE applied for determination of Cr(VI) traces using catalytic adsorptive striping voltammetry (CAdSV) will be presented. The film electrode is characterized by its very good surface reproducibility (not less than 2%) and long-term stability (1500-2000 measurement cycles). The mechanical refreshing of mercury film is realized in the specially constructed device, in a time shorter than 1-2s. In the paper, it will be proved that a mechanically weak hanging mercury drop electrode (HMDE) may be substituted by mercury film Hg(Ag)FE electrode with a surface area adjustable from 1.5 to 12 mm2. For the electrode surface 4 mm2 the detection limit obtained for Cr(VI) was 0.19 nM, while the linearity range measured for a 20s accumulation time was between 0.5 and 50 nM. The relative standard deviation (R.S.D.) in determination of Cr(VI) varied from 1 to 5%. The influence of the excess of Cr(III) on determination of Cr(VI) was analyzed using samples from the Dobczyce reservoir spiked with known amounts of Cr(VI) and Cr(III).