COULOMETRIC TITRATION OF MICROGRAM AMOUNTS OF AMERICIUM AT CONDUCTING GLASS ELECTRODE

Coulograms of Am(III) in O.lM LiClO4-0.05M Na2CO3 electrolyte exhibit a well-defined wave for the Am(III)-Am(V) oxidation step at the conducting glass electrode. This wave provides the basis of a method for the quantitative titration of this element at the level with a 30-microgram precision of 1.5%. The method is restricted to pure solutions. Most cations interfere: Pu, Np, V, and Ru are reduced near the Am(III)-Am(V) wave. Fe precipitates and scavenges Am. Radiolysis products from radioelements also interfere. SO42- produces an anodic shift, and F- damages glass surfaces. Cl- or NO3- do not interfere at 0.01M. Corrections are required for the partial oxidation of Am(V) to Am(VI) and the reduction of Am(VI) by water. The useful pH range is 10.0 to 11.5. The Am(III)-Am(V) couple is indicated to be irreversible. © 1969, American Chemical Society. All rights reserved.