Stainless steel electrode for simultaneous stripping analysis of Cd(II), Pb(II), Cu(II) and Hg(II).

Traditional electrodes for stripping analysis generally have narrow electrochemical window, require the modification of electrode or the addition of additional ions. To solve these problems, stainless steel has been used as the electrode for electrochemical stripping analysis for the first time. Square wave anodic stripping voltammetry (SWASV) has been used for the detection of Cd, Pb, Cu, and Hg. Type 304 stainless steel electrode gives well-defined, sharp, and separated stripping peaks for these metal ions. The electrode, best operated at + 0.3 V (Hg), - 0.05 V (Cu), - 0.41 V (Pb), and - 0.7 V (Cd) and after a 300 s deposition at - 1.0 V, has linear responses in the concentration ranges of 0.075-5 μM for Pb and Cu, 0.5-5 μM for Cd, and 0.1-5 μM for Hg. The limits of detection (at S/N = 3) are 0.033 µM for Pb, 0.0073 µM for Cu, 0.23 µM for Cd, and 0.028 µM for Hg. The reproducibility, expressed as relative standard deviation, is 3.2% for Pb, 2.6% for Cu, 5.1% for Cd, and 2.5% for Hg (each 1 μM levels; for n = 6). The electrode was successfully applied to the determination of the ions in spiked groundwater samples. This study shows that stainless steel is a better alternative to mercury electrode for stripping analysis because of its well-defined and sharp stripping peaks, high sensitivity, low background, low toxicity, good reproducibility, and much wider electrochemical window.