Batch and flow determination of uranium(VI) by adsorptive stripping voltammetry on mercury-film electrodes

Trace amounts of uranium(VI) were determined by square wave adsorptive stripping voltammetry on a mercury-film electrode on a batch configuration using a rotating disc electrode (RDE) with 8-hydroxyquinoline as complexing agent or, alternatively, on a flow configuration with a novel wall-jet cell (WJC) and cupferron as complexing agent. Square wave stripping was as sensitive as linear sweep stripping, showed good background rejection and was 16 times faster than differential pulse stripping. Cupferron was a better ligand than 8-hydroxyquinoline in terms of sensitivity, selectivity and easy film cleaning but was less stable. The batch and flow methods were both suitable for determining lower uranium(VI) concentrations for which flow injection schemes were impractical, and application of the RDE and WJC methods to a reference seawater sample yielded accuracies of 7.2 and 4.2 per cent and relative standard deviations of 7.8 and 8.3 per cent, respectively. Further development could produce a portable computer-controlled flow system with a dedicated potentiostat.