Calibrationless determination of mercury by flow-through stripping coulometry.

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.