The electrochemical detection of arsenite with silver wire (SWE) or silver disc (SDE) electrodes was carried out in inorganic aqueous solutions, which are similar to those found under natural conditions. Cyclic voltammetry (CV), linear sweep voltammetry (LSV) and anodic stripping voltammetry (ASV) were applied. The investigated factors were pH, nature and concentration of supporting electrolyte and deposition time and voltage for ASV. The changes in the As(III) anodic peak current and potential in standard solutions (e.g., 0.1 mol L-1 Na2SO4, NaNO3, HNO3 and H2SO4) were evaluated. The neutral and basic media of inorganic salts were found to enhance the silver electrode sensitivity more than the acidic media. Thus, it was possible to work in alkaline medium with increased sensitivity for As(III) (limit of detection of 90 ng L-1). The improved analytical response made this system comparable to a nanoarray electrode. As the range of use of these electrodes was wide, SWE (area of 6.47 mm²) was applied to monitor tap water using 0.1 mol L-1 Na2SO4 as supporting electrolyte to successfully detect quantities above 0.5 mg L-1 As(III).
arsenite electrooxidation; silver electrodes; electrochemical detection; tap water
