The determination of bound nitrogen in uranium hexafluoride with an ammonia electrode

Uranium hexafluoride reacts with nitrosyl fluoride (NOF), nitryl fluoride (NO₂F), and nitrogen oxides to form solid compounds such as nitrosyl heptafluorouranate (NOUF₇) and nitryl heptafluorouranate (NO₂UF₇). Since these compounds are undesirable impurities in uranium hexafluoride, a method has been developed for the determination of these nitrogen oxyfluorides in uranium hexafluoride. Uranium hexafluoride is hydrolyzed in a potassium permanganate solution which converts the uranium hexafluoride to uranyl fluoride and the nitrogen oxyfluorides to nitric acid. The nitrate is reduced with aluminum powder to ammonia, which is then measured with an ammonia electrode in a basic solution. The method is relatively interference-free because the electrode is a gas-sensing device. The detection limit is 0.8 μg bound N/g U, and the precision at 3 μg bound N/g U is ± 16%.