Subtractive anodic stripping voltammetry with twin identical mercury-film electrodes differing in their convection transport during deposition

Subtractive anodic stripping voltammetry based on the use of different convection rates at the surface of two identical working electrodes during the deposition step is described. Twin mercury-film glassy-carbon disc electrodes, one rotated and one stationary, are used to demonstrate this technique. All background currents arising from nonconvective-dependent sources are effectively compensated. Deposition times of 3–5 min suffice for measuring heavy metal ions at sub-μg ml^-1 concentration levels.