A simple and rapid procedure for the calibrationless determination of trace concentrations of As(III) and total As in contaminated water samples is presented. Arsenic is preconcentrated as As(III) in a flow-through cell with a gold plated porous electrode and is then stripped anodically by a constant current. The stripping chronopotentiogram is registered and evaluated. The As concentration is calculated directly from the combined Faraday's laws. The total As content was determined after converting all As species to As(III) by microwave-assisted reduction with hydrazine hydrochloride in a closed vessel. The detection limit was found to be 0.15 microg/L and the linear response range was 0.5 to 10,000 microg/L. Tap water, surface water, and waste water samples were analyzed.

Zn, Cd, Pb and Cu are deposited in a porous¯ow-through electrode plated with mercury and then are stripped by constant current while the stripping time is measured. Since complete electrochemical deposition can be achieved, the analyte concentrations can be directly obtained from Faraday's laws i.e., the method is denoted as calibrationless. The in¯uence of the deposition potential, stripping current, carrier electrolyte composition, Cu content and sample matrix was investigated. The optimum conditions are: deposition potential: À1600 mV, stripping current: 200 mA, carrier electrolyte: 0.1 molaL sodium sulfate at pH 4±5. The dynamic range of the method is from about 0.1 ngamL to few mgamL. The repeatability of the method is 1±2 % in the optimum concentration range. The procedure was applied to the analyses of water samples, geological, and biological materials.

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Trace concentrations of Hg were determined in a flow-system by constant current stripping chronopotentiometry in coulometric mode. Mercury was electrodeposited from the flowing sample solution in an electrochemical flow-through cell on a large surface porous electrode plated with a thin layer of gold. The deposited mercury was then stripped with constant current and the potential change of the working electrode was recorded and evaluated. Since complete electrochemical yields were achieved at both the deposition and dissolution steps, the mercury concentration in the sample solution could be calculated from Faraday's law. The detection limit and reproducibility of the method were about 0.1 ng/ml for 10 ml sample solution and 4%, respectively. The time for a complete analysis was 2 to 5 min. The utility of the method was demonstrated with the analysis of reference materials, water samples, waste materials, plants and charcoal catalysts.