Direct determination of uranium in water by cathodic stripping voltammetry

Uranium was determined in fresh water and seawater by using 8-hydroxyquinoline(oxine) as the chelating agent in cathodic stripping voltammetry procedure. The peak height-uranium concentration relationship was linear up to about 30 nM U (at a peak current of 80 nA) when the scans were preceded by 1 min of stirred adsorption. The linear range is extended to higher uranium levels by reducing the sensitivity by adsorbing less complex ions on the electrode, i.e., by using a shorter adsorption time, or by adsorbing without stirring. The sensitivity for uranium in a synthetic electrolyte solution was about 10% greater than in seawater, presumably due to the absence of carbonate ions which compete with the oxine for uranyl ions and the major cations which partially saturate oxine in seawater. This similar sensitivity in fresh and seawater is in contrast to the poor sensitivity that was obtained by SCS when using catechol as the chelating compound in fresh water conditions, as its sensitivity was 10-20% of that in seawater