Determination of Americium in a Nitric Acid Medium Using Second-Order Derivative Spectrophotometry

A second-order derivative spectrophotometric method has been developed for the determination of microgram quantities of trivalent americium in a nitric acid medium containing plutonium and uranium. The second-order derivative absorbance of the americium at 503.5 nm is used for the quantitative analysis. In the determination of 5.8 μg/ml and 3.9 μg/ml of americium, the presence of a 100-fold amount of plutonium and a 600-fold amount of uranium could be tolerated, respectively. The trivalent americium. in the concentration range of 1 - 11 μg/ml has been determined with good precision. The detection limit was 0.3 μg/ml at 3 times the standard deviation (3σ). The relative standard deviation was less than 2.1% for a sample of uranium-plutonium mixed oxide. The proposed method does not require the complicated separation step of plutonium and uranium.