Direct determination of plutonium(V) and neptunium(V) complexation by carbonate ligand with CE-ICP-sector field MS

Direct determination of the stability constants of some pentavalent actinides (Np and Pu) with carbonate ligands was investigated by CE-ICP-sector field MS (SFMS). The high sensitivity of ICP-SFMS coupled with the high separation power of CE makes it possible to determine the mobility of each species as well as the stability constants with good accuracy. A procedure for preparing pentavalent plutonium at trace level has been successfully tested enabling the study of Pu(V) complexation by CE-ICP-SFMS. Stability constants β1, β2 and β3 have been obtained at 25 ± 1 degrees C at a constant ionic strength of 0.37 M in NaClO4 for K1 and NaCl for β2 and β3. The results were extrapolated to zero ionic strength and compared with data available in the literature for Np(V). The following stability constants were obtained for a Pu(V)/CO3 system: log β01 = 4.95 ± 0.10, log β02 = 6.34 ± 0.10, and log β03 = 5.61 ± 0.16. (authors)