AB-226
Determination of arsenic by stripping voltammetry at the rotating gold electrode
Tóm tắt
This Bulletin describes the determination of arsenic by anodic stripping voltammetry (ASV) at the rotating gold electrode. A determination limit of 0.5 μg/L can be achieved with 10 mL sample solution. A differentiation between the As(III) concentration and the total arsenic concentration can be made by appropriate selection of the deposition potential. The analyses are performed with a special gold electrode whose active surface is located laterally; c(HCl) = 5 mol/L is used as supporting electrolyte. For the determination of the total arsenic content, As(III) and As(V) are reduced at -1200 mV by nascent hydrogen to As0, which is preconcentrated on the electrode surface. If the deposition is carried out at -200 mV then only As(III) is reduced; this allows the differentiation between total arsenic and As(III). During the subsequent voltammetric determination the preconcentrated As0 is again oxidized to As(III).