A precise uranium assay using solvent extraction and spectrophotometry

The uranium spectrophotometric measurement using the uranylnitrate-quaternary amine solvent extraction method is investigated to identify factors that affect precision and accuracy of the uranium determination. The inherent spectrophotometric precision was measured with neutral density filters in the sample light path and was found to be <0.1% relative standard deviation (RSD). Under selected experimental conditions, temperature instability has a -0.02% effect on the extraction, and a -0.4% effect on the absorbance of the uranium extract in 2-nitropropane or methyl isobutyl ketone solvents. Under optimum conditions at the 10 mg uranium level, RSDs of ∼0.1% resulted. (author) 19 refs.; 4 figs.; 3 tabs