Simultaneous calibrationless determination of zinc, cadmium, lead, and copper by flow-through stripping chronopotentiometry

Zn, Cd Pb and Cu are deposited in a porous flow-through electrode plated wi th mercury and then are stripped by constant current while the stripping ti me is measured. Since complete electrochemical deposition can be achieved t he analyte concentrations can be directly obtained from Faraday's laws i.e. , the method is denoted as calibrationless. The influence of the deposition potential, stripping current, carrier electrolyte composition, Cu content and sample matrix was investigated. The optimum conditions are: deposition potential: -1600 mV, shipping current: 200 mu A, carrier electrolyte: 0.1 m ol/L sodium sulfate at pH 4-5. The dynamic range of the method is from abou t 0.1 ng/mL to few mg/mL. The repeatability of the method is 1-2% in the op timum concentration range. The procedure was applied to the analyses of wat er samples, geological, and biological materials.