SQUARE-WAVE VOLTAMMETRY OF URANYL HUMATE COMPLEX

Square-wave voltammetric measurements were applied to the identification and determination of the uranyl-humate complex in 0.55 mol l-1 NaCl solution and in artificial and natural sea water. The sensitivity of the square-wave voltammetric response can be enhanced by the accumulation of the complex because of its strong adsorption at the electrode surface. The detection limit for the uranyl-humate complex after an accumulation period of 10 min at a potential of 0.0 V vs. a sodium chloride-saturated Ag/AgCl electrode was found to be (5.0 +/- 0.2) x 10(-9) mol l-1 and the maximum surface concentration of the adsorbed reactant was GAMMA(s) = (7.1 +/- 0.1) x 10(-11) mol cm-2. The mechanism of the electrode reaction was established. The interferences of various cations and surface-active substances were studied.