Potentiometric stripping analysis for mercury after preconcentration in a potassium permanganate trap

Water samples of total volume 0.5–5 l, containing mercury in the range 0.05–5 μg l^-1 are oxidized with excess of potassium permanganate and then reduced with tin(II) chloride. The mercury is transferred to 5–10 ml of a dilute potassium permanganate trap solution by cycling air through the sample and the trap solution. The mercury(II) content of the trap solution is determined by potentiometric stripping analysis. The accuracy, precision and detection limit of the technique are discussed.