Electrochemical detection of mercury, cadmium, lead, and copper using boron-doped diamond electrodes

Anodic stripping voltammetry (ASV) and boron-doped diamond (BDD) electrodes were used to detect mercury, cadmium, lead, and copper at low part-per-billion (ppb) concentrations. Two types of BDD electrodes were used, free-standing polished electrodes, and unpolished BDD films grown on silicon substrates. The electrochemical detection of mercury was difficult in all of the matrices investigated: nitrate, chloride, thiocyanate, phosphate, and sulfate. Precipitation of mercuric or mercurous salts on the electrode surface was the likely cause. The addition of an auxiliary element improved the detection of mercury. The detection of cadmium and lead was more straightforward. The addition of copper improved the detection of lead, but not cadmium. The BDD electrode was used to determine the complexing capacity of a river water sample for lead. The application of ultrasound during the deposition step of ASV improved the detection of cadmium, but eventually damaged both types of BDD electrodes.