Differential pulse voltammetric methods for the simultaneous estimation of uranium-iron and uranium-cadmium mixtures in solution

Abstract

Differential pulse voltammetric methods have been developed for the simultaneous estimation of the constituents of uranium-iron and uranium-cadmium mixtures in solution. A mixture of 1M H₃PO₄−1M KH₂PO₄ (with a pH≈1.5), was found to be the most ideal supporting electrolyte for both methods, among many that were evaluated for their suitability. In uranium-iron mixtures the calibration for iron was found to be linear up to 150 μg ml⁻¹ (r²=0.9986), while that of uranium up to 500 μg ml⁻¹ (r²=0.999). Iron at 6.7 μg ml⁻¹ level could be determined in the presence of 800 fold uranium (wt/wt) without significant interference. Uranium at 21 μg ml⁻¹ level could be analyzed with 5-fold iron (wt/wt). This upper limit of iron was due to the precipitation of iron as phosphate. In the case of uranium — cadmium mixtures, cadmium calibration for cadmium was found to be linear up to 1300 μg ml⁻¹ (r²=0.9993). Concentration levels of 4.6 μg ml⁻¹ Cd could be determined at a 500-fold excess (wt/wt) of uranium. Uranium calibration was linear up to 500 μg ml⁻¹ (r²=0.999) and 21 μg ml⁻¹ uranium could tolerate up to a 1000-fold excess of cadmium (wt/wt). Both procedures could tolerate 10 μg ml⁻¹ levels of metal ions, such as chromium, copper, manganese, molybdenum and vanadium.