Robotic heavy metal anodic stripping voltammetry: ease and efficacy for trace lead and cadmium electroanalysis

A novel strategy for the automation of trace lead (Pb2+) and cadmium (Cd2+) anodic stripping voltammetry (ASV) is described. This was achieved using an electrode assembly comprising a small standard reference electrode, a Pt wire counter electrode, and an in situ bismuth-plated pencil lead working electrode for ASV in a robotic device adapted for measurements in a 24-well microtiter plate format. The movement of the electrode assembly through individual wells was by computer-controlled micropositioning, and each microtiter plate run included a sequence of electrode pretreatment, water rinsing, and simultaneous Pb2+ and Cd2+ ASV measurements. Analyte concentrations down to 2 mu g/L (Pb2+) and 20 mu g/L (Cd2+) could be measured in drinking and tap water, a wastewater reference material and a soil sample, with an accuracy and standard deviation typical of stripping analysis. This robotic electrochemical strategy offers automated trace metal analysis with simple instrumentation and is suggested as an option for routine use in analytical laboratories such as those providing environmental heavy metal testing services.