Spectrophotometric analysis of uranium concentration at trace level in PuO₂ product

An extractive spectrophotometric method was developed for the determination of uranium concentration in plutonium oxide powder. A liquid-liquid extraction was employed to extract selectively uranium in trace level present in plutonium nitrate solution after converting all plutonium to in-extractable (III) oxidation state using non-corrosive salt free reducing agent. Concentration of uranium in organic phase was determined by spectrophotometry using 2-(5-bromo-2-pyridylazo-5-diethylaminophenol) as a chromogenic agent. Molar extinction coefficient was found to be 72,142 ± 2.0% L mol^-1 cm^-1 and the linear dynamic range was found to be 2-30 µg per aliquot with a relative standard deviation of 5%. This method can be employed for the determination of uranium concentration in plutonium oxide product of nuclear reprocessing. (author)